Jameschin

RapidKL GPS Buses

2011-03-10T22:57:00.012+08:00

RapidKL is converting all its buses to be GPS enabled so that Touch N Go cards can be used instead of having to buy tickets from the driver. The Touch N Go cards are the same ones which can be used for the road tolls and not the monthly Rapidpass.

I bought my Touch N Go card for the LRT as at that time it couldn't be used on the buses. But now that the RapidKL buses are getting GPS this LRT Touch N Go card can be used for the buses.

GPS system on the RapidKL bus. It detects where the bus is for charging the fare.

Surprisingly though the card no longer works for the LRT. There's a beep and an error if touched at the LRT turnstiles. So I've had to use the old stored value LRT ticket.

When getting on the bus touch the Touch N Go card at the front detector. Your balance in the card will be displayed on the digital display. You will be charged the maximum fare at this stage. It could be RM2.50 or RM3.00 depending on how far the bus is from the endpoint of its journey. When alighting touch the card again on the detector either at the front or at the other one next to the rear door. Your card will now be charged the correct fare. If you forget to touch the card on the way out, you will be charged the maximum fare.

Rear touch detector.

If the bus is full such as in the mornings before work or in the evenings after work, you can go in by the rear door. You can then touch the card at the rear detector which will charge the maximum fare. On the way out touch the card again on the detector for the correct fare deduction.

You can also top-up your Touch N Go card on the bus. The top-up machine is at the front near the driver. If you don't have a card you can buy a new one here as well.

I think if reloading you don't have to touch the card on the smaller detector first before reloading. Because if you do you may get charged for a double trip. Simply reload the card by going to the reloading/purchasing machine and pressing the reload button, feeding the machine with your bank note and then touching the card on the machine. This should register that you have entered the bus. I found that on exit I was charged double fare when I touched the other smaller panel first before reloading.

Machine for reloading or purchasing a new Touch N Go card. Wrong usage may cost you double fare.

The GPS display next to the driver will show where the bus is. It updates as the bus moves along.

The Touch N Go GPS RapidKL buses have appeared on the Jalan Klang Lama route first. At the Taman Jaya—PJ Old Town route the buses do not have GPS yet. It is expected that by the end of March 2011 all the RapidKL buses will be GPS enabled for Touch N Go usage.

Copeland Digital Scroll

2010-12-30T00:26:00.015+08:00

The Copeland Digital Scroll air-conditioning compressor is an alternative to the inverter compressor. It is a variable refrigerant flow (VRF) air-conditioning system. Copeland Digital Scroll is provided to York’s NetCool air-conditioning system to provide modulated cooling capacity.

During compression one scroll remains stationary (fixed scroll) while the other form is allowed to orbit (orbiting scroll) but not rotate around the first form. As this occurs pockets of refrigerant gas between the two forms are slowly pushed to the centre where the discharge pipe is located. The gases are simultaneously being reduced in volume as this occurs which causes the refrigerant compression and the gas exit at the central port is at high pressure. Because several pockets are compressed simultaneously it is a smooth process. Both suction at outer portion of the scroll members and discharge is continuous.

The Copeland scroll has a unique feature called axial compliance which means that the fixed scroll at the top is allowed to move vertically in a very small amount, for e.g. 1 mm. When it is lifted up by 1 mm there is no compression. This is the unloaded state. When it is pressed back down to the orbiting scroll, compression resumes. This is the loaded state. A solenoid valve is closed during the loaded state (no voltage) and open during the unloaded state (full 220 volts).

In a 20 second cycle if the loaded state is 10 seconds and the unloaded state also 10 seconds the compressor’s output is 50%. If the loaded time is 15 seconds and unloaded time 5 seconds the compressor’s output is 75%. The wide capacity range from 10%–100% results in an unmatched output from the Digital Scroll. This wide capacity output is continuous and seamless and ensures that there is a very tight control on room air temperature. Normal thermostat controlled compressors cannot match this accurate temperature control.

Copeland Digital Scroll is used in Delta Shopping Mall, one of the most prestigious shopping malls in Sibu, Sarawak. 275 ceiling cassette type indoor units and 32 outdoor units provide climate control for 100 shoplots with floor areas ranging from 350–5,900 ft² and one supermarket with floor area of 22,500 ft². Developers selected York air-conditioning featuring Emerson’s Digital Scroll Technology.

Digital Scroll is also used in Advanced Business Park, Beijing which is China’s largest central air-conditioning project. Powering Samsung’s 13,122 indoor VRF central air-conditioning units and 3,000 outdoor units installed in 1,000 companies, five star hotels and apartments housed in 500 individual buildings within Advanced Business Park, Copeland Digital Scroll is being used for climate control and energy efficient problems.

Moscow's Underground Metro

2010-10-28T14:09:00.001+08:00

Moscow is the capital city of Russia with a population of 9 million. The St. Basil’s Cathedral in Red Square with its multi-coloured domes has long been an icon for the biggest country in the world. The easiest, quickest and cheapest way around Moscow is the metro. Boasting some 10 lines and more than 150 stations Moscow’s underground system transports up to 9 million people a day, more than the London Tubes and the New York City system combined.

The first metro station was opened in 1935. One of the project managers for early construction was Nikita Khrushchev who then later became the prime minister of USSR from 1958 to 1964. The early stations were very deep as they were designed as air raid shelters in case of war. The Moscow metro is famous for the art design of many of its stations.

Art design in a Moscow subway station.

Original article from Jurutera January 2007.

Batu Caves with Lili

2010-08-08T16:38:00.014+08:00

My sister Lili, who's presently on holidays here from Los Angeles, thought we should check out Batu Caves. I've never been there before, not inside. Seen it countless times from the outside but never went inside.

There was a Sai Baba convention going on in the grounds.

Lili checking out the Sai Baba convention.

Lots of people, speech was in english, but didn't see any food.

There's a monkey god statue in the compound.

He is big and green.

With nicely cut toenails.

There's this small cave on the left of the main cave which I didn't know about. Fortunately my sister did and so we went in. Only costs RM2 per person. Inside this small cave are some rather nicely made figurines.

This guy looks more human than the sleeping buddha.

Then we went to the main cave which is the one with the one with the 272 steps to reach it.

At the bottom before the climb.

Took the photo now before getting all sweaty.

This is the main cavern at the top. There really isn't much here but the view down the mountain is quite good. There are a few shops but filling the fridge musn't be fun at all.

Going back down the stairs. The Lord Murugan statue is the tallest in the world. The gold paint is from Thailand.

Monkey giving me a fierce stare.

Happy monkey.

Then we went to another cave. It has some more figurines but I think the first cave was better.

This is quite cute.

Deeper into the cave are some snakes.

IBM Travelling Exhibition & Vienna Waste Station

2010-02-20T01:04:00.005+08:00

Thought I should do a bit of blogging to flex my newly transplanted right hand tendon. The arm wound is slowly healing but the fingers are very stiff. I can't clench my right fist at the knuckles. I could force it shut but that would probably snap the tendon and doc said he won't be doing the surgery again if that happens. I'm using one finger typing and writing is even more difficult.

Surprisingly got a bit of time until the next load of work comes in. Will be going back to UMMC on 25/2/10 hopefully for stitch removal and until then I won't be working. If the wound has healed I can probably return to work otherwise may need an MC extension. It's really boring here at home and I'd prefer to work even if it sucks.

These are probably the last pics from the timber CD. Still have lots of content not yet blogged such as the China trip, technical stories, etc.

This is the IBM Travelling Exhibition which would've happened a long time ago before Yahoo!, Google and YouTube. It was designed by architect Renzo Piano.

The exhibition can be packed up and transported elsewhere.

Outside view.

Inside view.

So that was a bit of retro.

This is the Vienna Waste Transfer Station / Incinerator, included here because it's so huge and the roof structure is timber.

Elevation view.

Inside view.

Brick Arches

2008-04-19T22:11:00.043+08:00

Here are some photos showing how a brick arch can be built. It's from a US construction site for a bungalow house. Many of the houses in Australia are not built like ours. Blocks are used for load-bearing walls and then the in-situ first floor slab is cast on top of these load-bearing walls. The slab usually has no beams. There are also usually no columns because of the load-bearing walls. Everything is supported on walls, not columns. Walls don't need formwork but columns do. Load-bearing wall construction is faster and less labour intensive.

The problem with this sort of construction is that an opening, such as for a door or window, cannot be broken into the wall at a later time because it is load-bearing. Creating a door during renovation at a later date may cause the ceiling to collapse. Thanks to dad who told me this. The photos below show how a large brick arch is built.

Placing wooden formwork for brick arch.

Placing wooden formwork for brick arch at another location, same house.

Bricklaying on the wooden arch formwork.

Brick ties are placed every so often.

There are actually two rows of bricks, one for the front and one for the back face. The centre is initially empty. Later concrete is poured into the centre. The brick ties, which are bent pieces of wire, bond both sides together.

Concreting the centre of the arch. The brick ties bond both sides to the concrete.

Looks like something else in the concrete as well, maybe broken bricks or tiles.

Finishing off at the crown.

Done!

Source of images:
http://members.cox.net/benito.loyola/house/Loyola_Lot_95_notes.htm
Fast broadband connection recommended
700+ images on one page. Otherwise just look at them here :-)

Aquadom in the Radisson SAS Hotel, Berlin, Germany

2007-08-19T17:12:00.001+08:00

The AquaDom in the lobby of the Radisson SAS Hotel, Berlin, Germany is the largest cylindrical aquarium ever built. It is 25 m tall with a built-in glass enclosed elevator which allows visitors to travel through the tank to reach a sightseeing point and restaurant under the glass roof at the top.

The 25 m tall AquaDom in the Radisson SAS Hotel, Berlin, Germany.

The AquaDom contains about 900,000 litres of seawater and 2600 fish of 56 species.

View of AquaDom from interior suites, overlooking the atrium.

Night view of the roof over the AquaDom.

The AquaDom was opened in December 2003. The glass is actually acrylic, which is a petroleum product and highly flammable. During machine cutting the acrylic has to be cooled by water spray to prevent a fire from starting.

The acrylic glass cylinder was constructed by the U.S. company Reynolds Polymer Technology. The outside cylinder was manufactured on-site from four pieces, the inside cylinder for the elevator was delivered in one piece. The AquaDom is the largest acrylic glass cylinder in the world, with a diameter of over 11 m built on a 9 m tall concrete foundation.

Two full-time divers are responsible for the feeding of the fish and maintenance of the aquarium.

Looking upwards through the centre of the AquaDom.

Construction in progress.

Acrylic cylinder has been installed.

Installation of the inner elevator cylinder.

Cranes used for the construction.

NVIDIA GeForce FX 5500 & ASUS ATI A9550GE

2007-06-03T22:39:00.001+08:00

This was my old graphics card, the NVIDIA TNT2 Model 64 with 32 MB of RAM.

NVIDIA TNT2 Model 64 32 MB RAM.

It doesn't work with Vista because the refresh rate cannot be set to another value other than the default refresh rate decided by Vista. Unfortunately this flickers which causes eye strain if staring at the monitor for an extended period of time.

So I walked over to the Digital Mall at Section 14 in PJ to look for a new GPU. My computer has the old AGP 8X slot (17 Gbps) rather than the newer and faster PCI Express (32 Gbps for PCI-E x16) GPU slot. I wasn't sure if I should get a 128 MB or 256 MB card. Minimum requirements for Vista is 128 MB RAM and Pixel Shader 2.0 for the 3-dimensional and semi-translucent Aero effects. A 256 MB card would be nice but it could be very expensive. The guy at the counter suggested I buy a PCI-E card but you need to buy a new computer as well to use that card. Then he informed me that I can buy the NVIDIA GeForce FX 5500 128 MB RAM for only RM150.

NVidia GeForce FX 5500 packaging.

The NVidia GeForce FX 5500 graphics card inside the box.

The guy took out the first GPU from its box, looked at it and said there is a problem with it. He took out the second card from the box and that also had a problem. He gave me the third box which was apparently okay and so I paid RM150 in cash and took the long walk home. Fortunately the weather was good and it was also the Agong's birthday holiday.

The guy said that the Vista drivers for this graphics card can be downloaded from the NVIDIA website. When I got home, I pulled out the old TNT2 and installed the new card which worked fine. I surfed the web with the new card and found that the Vista drivers for the FX Series are available from the NVIDIA website, confirming what the guy had said.

Everything was going well until about 5 minutes later, when I had come out from sitting on the toilet. I discovered that the computer had frozen. The keyboard and mouse wouldn't respond. No idea how long it had been like that for. And then on moving the mouse the display at the top of the monitor became garbled.

I pressed reset and the PC proceeded to reboot. But then it froze and just kept going "beep, beep, beep, beep...". I pressed reset the second time, the PC restarted but the same thing happened. So I switched off the power and disconnected everything. As this card has no cooling fan I put my finger on the heatsink. It was hot like hell, it felt like an iron. Fortunately I was eating my fruit and veges and didn't have constipation. I may have burnt my father's office to the ground.

I pulled out the card and rechecked the PC with my old TNT2 which worked fine. Then I took the long walk back to Section 14. The guy's friend said there's a problem with the card, it works with Vista but it lags. I informed him I'm still running XP not Vista but the thing had overheated and it needs a cooling fan. He asked if I must have NVIDIA which I said no, just something that works with Vista and has Pixel Shader 2.0.

He brought out another card, the ASUS ATI A9550GE. This one is also for AGP 8X and has 256 MB DDR RAM and costs RM180. It has a 3-year warranty and all the drivers are on CD which means no downloading from the internet is required. The guy said that Vista recognises the card automatically and that no driver installation is necessary.

ASUS ATI A9550GE with 256 MB RAM and Pixel Shader 2.0 (Vista Aero compatible).

Contents inside the box.

I paid the extra RM30 and walked home again. When I got home I installed the card which worked fine. But unlike the NVIDIA which was recognised by Windows XP, which means that no driver installation was required, Win XP has no idea about this one. The display was on the low 640×480 resolution setting and couldn't be changed. Flickering was quite bad due to a low refresh rate which couldn't be changed either.

I proceeded to install the drivers from the CDs provided. There are 3 CDs being the:
1) Windows 2K/XP/64-bit drivers
2) Windows Vista 32/64 drivers
3) Multi-language manual

Installation was quite slow, taking more than 5 minutes. The .NET Framework was installed first and so it doesn't need to be installed later if using programs such as AutoCAD which also require the .NET Framework to be installed before the main program can be installed.

After installation everything has worked fine until now. With the TNT2, the maximum refresh rate for the 14" Samsung 45Bn monitor which is attached to this PC was 85 Hz. But with this new ASUS ATI, the refresh has increased to 90 Hz, but only at the 800×600 resolution. The refresh will drop to a maximum of 72 Hz for the 1024×768 setting.

Conclusion on the NVIDIA FX 5500: Overheats without a cooling fan and therefore it doesn't work. It is also being sold at Computer War at SS2 for RM139 (128 MB) and RM178 (256 MB). Their website and price list can be found here.

Conclusion on the ASUS A9550GE: Seems to be good value for money at only RM180 for a 256 MB card. AGP cards may be disappearing in the future anyway. Unfortunately a driver is needed under Windows XP and the installation is quite slow as .NET Framework is installed first.

Humberto Vidal Explosion

2007-03-26T21:34:00.001+08:00

At 8:30 a.m. on 21 November, 1996, because of a propane gas pipeline leak, a commercial building in San Juan, Puerto Rico exploded, killing 33 people and injuring at least 69 others.

Humberto Vidal Building after the gas explosion.

The building was in Rió Piedras, a shopping district in San Juan, Puerto Rico. It was a six-story building with a mixture of offices and stores. Humberto Vidal, Inc. had bought the building (the HV building) in 1984, and the company’s administrative offices occupied the third, fourth, fifth and sixth floors. The first and second floors of the building housed a jewelry store, a record store and a shoe store. The building was on the corner of José de Diego and Camelia Soto. The San Juan Gas Company (SJGC) was the local gas pipeline distribution company. The company had a 4-inch cast-iron gas main on de Diego. A 2-inch abandoned gas line, a pressurized steel service pipe, ran from the main to the Humberto Vidal building, about 6 to 8 inches east of the east wall. The service pipe did not enter the building, and gas had not been used in the building for more than 10 years. The Humberto Vidal Shoe Store was on the first floor, and its front door was on de Diego. The store was owned by Humberto Vidal, who owned other shoe stores in Puerto Rico as well.

On the week preceding the accident, many people said they smelled gas in the building. Several Humberto Vidal employees worked in the basement and on the first floor early in the mornings before the air-conditioning was switched on. They said they smelled a strong odour which smelled like gas. Those who worked in the basement complained of dizziness, nausea and difficulty in breathing. Most Humberto Vidal employees said they smelled gas as did some customers. The smell was reported to be strongest in the basement. The manager of the shoe store (who later died in the explosion) said that the employees could not go to the basement because of the strong smell of gas.

Some of the employees at the Chicken Kingdom had told their supervisor that they had smelled a strong odour of gas that came and went. The supervisor stated that he called the company that serviced his gas cooking equipment and had all of the equipment tested. No leaks were found. He stated that the equipment-company personnel assumed that the odour must be associated with gas work going on along Camelia Soto, since someone was constantly there checking for gas leaks.

The administrator of the Chicken Kingdom stated that he used a pay telephone to report to the SJGC that his employees had smelled gas. The SJGC employee receiving the call asked for the street name. The administrator explained to him that the smell came and went. The SJGC employee said the gas company would take care of the problem. The administrator stated that the SJGC employee did not ask for his name, for his company’s name, whether the smell was inside or outside, or any other questions. The administrator also said that the SJGC employee did not tell him what actions he should take. After he made the report the administrator said he saw an SJGC truck and SJGC employees working in the area and assumed that they had come in response to his call.

According to the SJGC, the first report it received of the odour was on Thursday, 14 November. The SJGC dispatcher on duty that morning said that the manager of the shoe store telephoned him at 8:15 a.m. The dispatcher said the manager told him that he smelled gas when he opened the store and that when he went into the basement, he could smell gas, although the odour was not very strong. The dispatcher stated that he recorded the call and told the manager what he told anyone who reported smelling gas–leave the basement door open and try not to turn on any electrical appliances or anything that has to do with electricity. The dispatcher sent a technician to investigate. The technician arrived at the shoe store about 9:30 a.m. and met with a store employee, probably the store manager. The two then walked down the basement stairs, which were on the east side of the building (the side next to La California). They walked to the north wall of the building (the wall along de Diego), where the manager pointed to the upper right part of the wall and said that the odour seemed to be coming from there. He told the technician that he smelled gas in the mornings when he entered the store. The technician had a gas detector with him, the kind that is not accurate unless it is turned on in an area that is free of gas. Once turned on and moved to an area that is suspected of containing gas, the detector will beep if it detects gas. The technician did not turn the detector on until he had been in the store for about 5 to 10 minutes. When he used it to test the basement air, the detector did not beep as it wasn’t calibrated correctly. This was the technician’s mistake.

On Friday, 15 November, the SJGC sent a brigade to the building. The brigade, consisting of four men and a leader, arrived at 8:15 a.m. The leader had been told by his supervisor that the store manager was complaining of an odour of propane gas inside the building. When the brigade arrived, the store manager told the leader that he smelled propane gas in the store, and both men entered the basement by the stairs at the east wall. In the basement, they walked about 12 to 15 feet north from the stairs, and the manager told the leader that they had reached the spot where he had smelled gas and that the odour seemed to be coming down from the basement ceiling. According to the leader, both he and the manager agreed that they could not smell gas at that time. The leader later stated that the manager had told him that sometimes in the morning when he opened the store he could smell gas. The leader did not have an instrument with him for testing the basement atmosphere for the presence of gas, so he went outside to test the underground with a combustible gas indicator (CGI).

Location map of the Humberto Vidal Building, Chicken Kingdom and CGI readings which were taken. Click on images to enlarge.

On Monday morning, 18 November, an HV employee told the manager that the odour of gas in the shoe store was very strong. The manager told her that he had already spoken with the SJGC and that the company was not paying much attention. She later stated that he asked her to go to the basement with him and that she walked from the staircase about halfway to the north wall, but could not go any farther because the odour was strong enough to make her dizzy and nauseated. She had to go back upstairs to get some air. The following day, Tuesday, 19 November, was a holiday, and the shoe store was closed.

The leader of the Wednesday, 20 November brigade stated that he understood that he was responding to a call reporting a strong odour of gas in the store. He was aware that other SJGC employees had previously responded to a similar complaint and that they had made some barholes. He said that when he arrived at the store, he talked to the manager, who, he claimed, said that he was not sure that what they were smelling in the basement was gas, but that his employees were telling him that it was gas. The leader said that he went throughout the basement with the manager checking for any gas pipe or odour of gas. He said he found neither. He did not use an instrument to check for gas, but he smelled a strong odour, which he believed to be the odour of rubber. He said that when he smelled what he believed to be rubber, HV employees were unpacking shoes, readying them to be put on shelves.

On Thursday, 21 November about 6:45 a.m., air-conditioning contractors (a father-and-son team) arrived to do the routine, monthly maintenance on the air-conditioners that they had been doing for the past 10 years. They met the store manager and the messenger outside. According to the messenger, the manager opened the door to the store and said that he smelled gas. The messenger said his stomach became upset and he told the manager to call the SJGC because the odour was so strong. The manager turned on the lights, and the four men entered the building together. The manager and the contractors walked through the store to the elevator on the west side of the building. The son (the father later died in the accident) later stated that when he entered the building, he did not detect any unusual odours but said the manager told him about detecting a strong odour of gas. The three used the elevator to go to the building receptionist area on the fourth floor, where the manager opened the office doors and left. According to the son, the building air-conditioners usually were not turned on until 8 a.m. or later. It was usual for the store manager to turn on all the air-conditioning units at their control panels, however, the son stated that when he worked on the basement air-conditioner, he would turn the unit on and off as needed. To perform their work, the contractors would feel the air-conditioner pipes after the air-conditioner had run for a while to assess whether the machine was working properly, and as needed, they would wash the compressor and filters. An employee who arrived at work between about 7 and 7:10 a.m. said that as she entered the building, she smelled the odour of gas, an odour that had been present for the past week and a half. She said the odour was strong enough that it “went over the top of the regular odour (shoes) of the store.” She recognized the odour as propane gas because she had a propane gas stove at home. As she did most mornings during this period, she mentioned the odour to the store manager. He told her that he would call the gas company again that morning and that he was continuing to keep a log of his calls. (His call log was not found after the explosion.) The store manager’s brother entered the store, and the three of them were together until 8 or 8:05 a.m., when the employee left the building to get breakfast. The manager’s brother stated that when he entered the building, he smelled propane gas.

The manager complained to him about the strong odour of gas and told him that he had become dizzy and nauseated. The manager asked him to go into the basement to check on the odour. The brother walked to the bottom of the basement stairs, sniffed the air, and would go no farther because his eyes became irritated and he could not stand the smell. He ran back upstairs, advised the manager to leave the building, and soon left himself. The son from the air-conditioning contractor team said that he completed his work on the third and fourth floors about 7:50 a.m. and left the building. He stated that his father began working on the fifth floor and was to work all floors other than the third and fourth. The son said that he was aware of the odour produced by the shoes stored in the building and of the smell of propane gas from the pipe system. He stated that he did not detect the odour of gas that day in the areas he visited.

In the meantime, the MCC (Maintenance & Construction Coordinator) had decided to send a third brigade, which he dispatched at 7 a.m. The workmen arrived about 7:30 a.m. and parked their truck on de Diego, in front of the building. The MCC said he sent the brigade to make sure there was no gas in the building and to learn what the HV employees were smelling when they opened the building. The brigade leader reported that he was given no instructions on contacts to be made at the building and that he had not been told that there had been previous complaints or what the previous SJGC crews had done. He said that because he was not told of the previous actions, he did not take with him any plans or other information about the gas piping in the area. He knew that there was suppose to be a map of the gas mains in the truck, but he did not consider the map important because he knew he could use his radio to obtain any information he needed. The leader said that he did not smell gas on the outside of the building when he arrived and that he did not see anyone at the store door. He believed the store had not yet opened because the outside roll-up door was halfway up and the inside door was closed. At no time did he or his brigade members meet with or talk to any HV employee.

Without referring to the gas main map in the truck, he went to the barholes he saw in de Diego, beginning in front of the entrance to the HV building and extending west to the intersection of de Diego and Camelia Soto. He believed that the barholes had been made the previous day by another brigade. He stated that the holes were about 18 inches deep and about 6 feet north of the curb. He believed their locations to be over the gas main because he recalled the location of the gas main from an earlier time when he saw it exposed to reestablish gas service to the school across from the HV building. He inserted his CGI probe into the holes and tested in each. He detected no odour of gas, and his CGI did not register any indication of a combustible gas.

The administrator of the Chicken Kingdom stated that as he drove past the HV building on his way to work, he saw the SJGC brigade working in the area. He said that about a half hour before the explosion he detected a “little” gas odour in the store when the breeze blew into the store. The leader had three new barholes made in de Diego, between the jewelry store and the manholes in the intersection of Camelia Soto and de Diego. He said that the holes were 18 inches deep and about in line with the previously made barholes that he had already tested that morning. No combustible gas was detected in the three new holes.

Next he had the crew make more barholes in the intersection of Camelia Soto and de Diego. As soon as the barholes were made, just before 8:30 a.m., he used his CGI and obtained a reading of 20 percent on the gas scale, but he detected no odour of gas. About 5 to 10 seconds afterwards, while he was standing on the manhole cover and another employee was making another barhole, the explosion occurred. The force lifted him into the air and threw him about 15 to 20 feet to the north.

The HV building was destroyed in the blast as was a major portion of the building that housed La California. Several other nearby buildings suffered moderate to severe damage.

Enron Corp. owns the SJGC, and the SJGC’s stock is wholly owned by Enron, its headquarters are in Houston, Texas. Enron was incorporated as Northern Natural Gas Company on 25 April, 1930, in Delaware. In 1980 the corporate name was changed to InterNorth, Inc. and in 1986 it was changed to Enron Corp. On or about 3 January, 1985, Petrolane Incorporated sold all outstanding stock of the SJGC, then a Delaware corporation, to The Protane Corporation and it in turn on the same date transferred the assets to InterNorth, Inc. The SJGC continues to be managed and operated by its own slate of directors and officers, and its chairman is the CEO of an Enron affiliate operation.

The gas leak was from an underground pipe leading to the Chicken Kingdom. The only known event that could account for the deformation of the plastic service line to the Chicken Kingdom was the construction of the 16-inch water main in 1992. The main passed directly beneath the plastic line, and there was no sand bedding beneath that segment of the plastic line, as there was beneath other line segments. The plastic line appeared to have been deformed by the backfilling or compacting of soil after it was backfilled over the water main. Once the plastic line was deformed, its wall was under stress, initiating a slow-growth crack in the wall of the pipe. The Safety Board concludes that the manner in which the water line was installed imposed excessive stresses on the plastic gas service pipe, which resulted in the pipe’s later failure.

A crack in the plastic gas pipe line to Chicken Kingdom caused the explosion.

Statistics from the explosion.

During investigations it was initially thought that methane gas may have caused the explosion. Methane gas could have been produced by the sewerage system. The difference between methane gas and propane gas is that methane gas is lighter than air while propane gas is heavier than air. Analysis of the deformation caused by the explosion showed that the explosion occurred in the basement, the lowest part of the building, which is consistent that it was propane, which is heavier than air. As to what actually caused the explosion, it is believed that a spark from the air-conditioner thermostat may have ignited the gas in the basement.

Shoe sole imprints on basement beam soffit indicating the explosion began in the basement, caused by heavier than air propane gas and not lighter than air methane gas.

Samples from the barholes were also tested for propane. One set of the two samples were subjected to comparative gas chromatography at a local laboratory, and the results confirmed the presence of propane in the sample taken from a barhole at the intersection of Camelia Soto and de Diego. The second set of sample was subjected to analytical gas chromatography and the results confirmed that propane was present in all three barholes and was the major combustible gas constituent in two of the three.

Analysis of explosive forces on the basement columns (click to enlarge).

Some data extracted from the report by The National Transportation Safety Board, Washington, D.C. 20594
Pipeline Accident Report – San Juan Gas Company, Inc./Enron Corp.
“Propane Gas Explosion in San Juan, Puerto Rico, on November 21, 1996”

Helios Flight 522

2007-02-01T22:39:00.000+08:00

Helios Airways Flight 522 was a Boeing 737-31S flight that crashed on 14 August 2005 at 12:04 p.m. Eastern European Summer Time (EEST) into a mountain north of Marathon and Varnavas, Greece, also 19 miles north of Athens' Eleftherios Venizelos Airport. All 121 people on board were killed, the highest death toll for an aviation accident in 2005 until the West Caribbean Airways Flight 708 in Venezuela just two days later.

The day before the fatal flight the technicians had tested the Pressurization Mode Selector (PMS) switch which permits pilots to control cabin altitude (pressure) but then left the switch on MANUAL. The normal position should have been AUTOMATIC so that the pressurization system adapts as the aircraft climbs.

The pressurization system works through the aircraft air-conditioning system by drawing in air from the front of the jet engines, the airflow being provided by the jet fans. The pilots should have normally checked the PMS switch setting during their pre-flight procedure but unfortunately they did not.

The next day Helios 522 took off at 9.07 a.m. local time on its route from Larnaca, Cyprus to Prague, Czech Republic with a stop at Athens. As the aircraft climbed over the Mediterranean, the cabin alert horn sounded. This is an avionics high temperature warning indicating that the systems were overheating. The pilots were confused as to what was causing the overheating. The aircraft continued to climb and the air pressure and oxygen levels in the cabin became dangerously low.

At 14,000 feet, oxygen masks were automatically deployed and the master caution light flashed in the cockpit. The flight crew had made contact with Helios maintenance engineers on the ground to ask them what should be done and they were told to remove the alarm circuit breaker to silence the horn. The captain left his seat to deal with this and probably became unconscious during his search. A short time after, the co-pilot also became unconscious.

The aircraft continued to climb until its flight management computer knew it had reached cruising height. The computer then took the plane into Athens airspace and entered a holding pattern. The pilot, a German, and the co-pilot, a Cypriot, suffered hypoxia due to lack of oxygen. During the onset of hypoxia, thinking becomes very illogical. Tests on the effects of hypoxia in a pressure chamber show that the subject finds it difficult to answer simple questions and mathematical questions, such as addition or subtraction of numbers after some time in a low oxygen environment.

As there was no response coming from the airplane, at 10.55 a.m. the Greek air force sent two F-16 fighter jets to intercept the plane. At 11.20 a.m. they caught up with the airliner at 34,000 feet over the Aegean Island of Kea and peered inside the cockpit. The F-16 pilots saw the co-pilot slumped over the controls but could not see the captain, and oxygen masks were dangling inside. “When a pilot has no communication with the control tower, the procedure dictates that other planes must accompany and help the plane land. Unfortunately it appeared that the pilot was already dead, as was possibly everyone else on the plane,” Cyprus Transport Minister Haris Thrasou said.

The jets then flew by a second time and they saw two people in the cockpit possibly trying to take control of the plane. At that time it was unclear if they were crew members or passengers.

Helios Flight 522 was circling over Athens with everyone unconscious or dead with the exception of 2 crew members, who later also perished.

After investigations it is believed that a steward, Andreas Prodromou, who had just begun flying lessons, attempted to take control of the plane. DNA testing revealed that the blood on the aircraft controls was that of the flight attendant Prodromou. The other was a female flight attendant. All the flight attendants would have donned their oxygen masks and loss consciousness due to lack of oxygen. The two people seen in the cockpit were wearing oxygen masks connected to portable oxygen tanks, which was why they were still alive. At 30,000 feet it isn’t possible to stay conscious for long, maybe 15 to 30 seconds.

Having been in the air for three hours, Helios Flight 522 ran out of fuel. The engines shut off and the plane crashed into a mountain north of Athens, killing everyone onboard.

Helios 522 crashes into a mountain after running out of fuel.

Since the September 11, 2001 attacks on the World Trade Centers, in order to prevent terrorists from entering the cockpit and taking over the aircraft, the cockpit door has an electronic combination lock. Therefore it is believed that the 2 crew who were using portable oxygen tanks were unable to enter the cockpit because of this combination lock. It is not sure how they did finally get into the cockpit. One theory is that as the plane ran out of fuel and the engines cut out, the lock lost power and the cockpit door could be opened. However, it was then too late.

There is an outflow valve at the rear of the Boeing 737 which can be opened or closed. In the closed position, cabin pressure is maintained. In the open position, air leaks out and the cabin is depressurized. This was the case with Helios 522.

The control of this outflow valve is via 2 electrical wires running in close proximity, perhaps in the same conduit. The second wire is a backup. Airplanes have backup systems, such as 3 hydraulic systems to manipulate the control surfaces for pitch, roll and yaw during flight. If one hydraulic system should fail, there are a further 2 for backup. It is very unlikely that all 3 systems should fail at the same time.

It is believed that Boeing may have made a design error with the 737 by placing these two wires in close proximity. If one should short-circuit or catch on fire, it will affect the backup wire, rendering the system inoperable.

A pressurization control incident with a Boeing 737-436 G-DOCE in May 2003 presented wrong indications to the pilots and the PMS was finally switched to manual position like that found in the Helios 522 wreckage.

The outflow valve main and backup wires were in close proximity possibly due to cost cutting.

According the Helios 522 final report, in a previous pressurization incident with the Helios accident aircraft: “The Captain stated that there might have been a problem with the outflow valve.” The Air Accident and Incident Investigation Board (AAIB) of Cyprus was not able to reach a conclusive decision as to the causes of this previous incident, but indicated as one of two possibilities: “An electrical malfunction caused the opening of the outflow valve.”

Southern Steel Mesh

2007-01-14T18:53:00.004+08:00

This was an Institution of Engineers, Malaysia (IEM) excursion on Saturday 23 October 2004 to Southern Steel Mesh Sdn. Bhd. Klang factory.

Southern Steel Mesh exports its products to several countries. Projects shown on the video presentation include the KL Sentral and KL Monorail Project. A subsidiary of Southern Steel Mesh is Southern Wire Sdn. Bhd which is in Shah Alam. Some of the products manufactured by Southern Wire are steel ropes and steel wires for mattresses. Another subsidiary of Southern Steel Mesh is Southern PC Wire which manufactures steel for the prestressed industry.

Brisk Steel Products Sdn. Bhd. was the factory which we visited. Brisk Steel Products (BSP) was incorporated in 1980 and is a subsidiary of the listed Southern Steel Berhad and is the leading steel fabric manufacturer in the country with its production plants strategically located in Klang, Prai and Pasir Gudang. Southern Pipe manufactures steel pipes such as water supply pipes.

The Technical Manager of the company presented some still images with the computer and projector. Southern Steel acquired the Brisk Group 2 years ago. Before that they were under Hong Leong. BRC is actually a brand name. However most contractors referred to the welded steel mesh or the welded steel fabric as BRC. The company was incorporated on 27 December 1980 and there are 3 plants in Malaysia being at Prai, Klang and Pasir Gudang.

The meshes are made of line (main) and cross wires electrically resistance welded together. This was introduced to Malaysia in the 1950’s. There are 4 types of standard mesh being types A, B, C & D. The properties of each type are as follows:

1) Type A Square fabric with 200 × 200 mm spacing
2) Type B Rectangular fabric with 100 mm main wire spacing and 200 mm cross wire spacing
3) Type C Long fabric with 100 mm main wire spacing and 400 mm cross wire spacing
4) Type D Small square fabric with 100 × 100 mm spacing

The table below shows the BSP Standard Fabrics which are manufactured by the company.

Click images to enlarge.

For the BSP reference number, the digit after the alphabet indicates the wire diameter in the main direction, for example A9 indicates a square mesh with a 9 mm diameter wire in the main direction.

BSP also manufactures special fabrics. BSP Special Fabrics refers to various combinations of wire spacing and diameter for the main and cross wires. The table below gives three examples of special fabrics. The first digit after the alphabet refers to the wire diameter in the main direction. The second digit after the slash refers to the wire diameter in the distribution direction.

Steel cages will be the company’s new product. An example of steel cages are the reinforcement cages for beams or columns.

The standard dimension refers to BSP Fabric manufactured either in sheet form which is 6 m length by 2.2 m width or in roll form which is 40 m length by 2.2 m width. However roll form fabric can only be produced for wire diameter of 6 mm and below. In Australia the standard width is 2.4 m. The reason that the standard width is 2.2 m in Malaysia is because if the fabric is 2.4 m wide it may not fit into the lorry. BSP Fabric is exported to Australia and other countries.

The term “cut-to-size” refers to BSP Fabric manufactured to any required dimensions to suit the intended purposes subject to the dimensional limitations of the fabricating machine or transportation. These mesh are tailor-made to eliminate wastage of material. Cut to size fabric can be used for two-way slab panel reinforcement.

Ribbed Fabric has been widely used as reinforcement for concrete structures in Malaysia. As stated on page 5 of the BSP Fabric Technical Handbook which we were given, advantages of ribbed fabric are:

Higher bond and anchorage characteristics of the ribbed wire

Ribbed wire is cold-rolled which gives rise to uniform plastic flow in the material. This gives more consistent material properties and better ductility.

Crack widths in concrete elements are controlled to the minimum because the force is well distributed through the bond effect of the ribbed wire when compared to plain wires.

Ribbed and plain fabric wire.

The company’s production process flow chart is reproduced below.

MS 144 and MS 145 stipulates that the minimum requirement for the characteristic yield strength of welded fabric is to be 485 N/mm² (Grade 485) and 500 N/mm² (Grade 500). We were told that fabric with a yield stress of 500 N/mm² is now available. It was asked how it is possible to make the yield stress 500 N/mm². It was asked whether it is the technology or the formula. We were told it is the formula. Steel is made from phosphorus (P), sulphur (S), manganese (Mn) and carbon (C). 10K steel has a carbon content of 0.08%–0.13% while 12K steel has a carbon content of 0.1%–0.15%. 10K steel is more ductile due to having less carbon content. The characteristic yield strength of reinforcement is shown below.

Yield strength of steel.

Previously only Southern Steel made mesh. However Amsteel is now also making mesh. Perwaja Steel is now under Maju Holdings and they are also planning on making mesh and that BSP would be facing more competition.

Some new products which BSP are manufacturing are BSP Fence, Twin-Wire Mesh and Engineered Mesh. Beam and Column Cages and Pilecaps are currently in the development stage. BSP Fence was compared to chain-link fencing. BSP Fence is very durable because it is galvanised against corrosion and guaranteed for long life. Chain-link fencing is usually PVC coated for rust protection.

Engineered fabric is specially configured to suit design requirements. Engineered fabric is not defined with a fabric notation. Each engineered fabric sheet will require a configuration drawing.

Bar-mats are prefabricated steel sheets consisting of high yield strength bars welded together with small diameter cross wires. The cross wires are spaced typically at 1000 mm centres or to design requirements. If main steel are needed in both directions bar-mats can be laid at 90^o to each other. Bar-mats can usually be placed by two people without the need of a crane.

The raw materials come in the form of wire rods. These are rolled up like electrical wiring. The wire rods are then cold-rolled to reduce their cross-sectional area. According to the BSP Fabric Technical Handbook it is stated that in general the higher the stress in the steel the higher the deflection. If the steel fabric is loaded to a stress greater than 460 N/mm² a higher deflection can be expected than with using normal reinforcement bars. In BS 8110 the yield stress for bending reinforcement is taken as 460 N/mm².

We were taken to the material testing room. A testing machine was linked to a PC. The fabric rods were tested in tension and also in compression. The display on the PC showed the load versus elongation graph. After the material had failed, two points were indicated on the load vs. elongation graph. They were the yield point and the failure point. Two rods were tested to failure. Due to the many people who were present it was not possible to see clearly but I presume one could have been a tension test while the other was a compression test.

A device was then fitted to the testing machine. A welded joint was then tested to failure. The load was reported as kg force by the computer. The steel and welding were much stronger than required.

The Southern Steel Mesh office building.

Inside the Brisk Steel Products factory building.

The wire rod raw material which is rolled up.

The Rocknes

2006-12-23T03:56:00.000+08:00

The M/V Rocknes which capsized so quickly.

Name: Rocknes
Flag: Antigua
Call Sign: V2OG8
Operator/Owner/Manager: Aboitiz Jebsens Bulk Transport Corp., Philippines
Registered Owner: Reederei Hans Jurgen Hartmann, Germany
Port of Registry: St. John's
Builder: J.J. Sietas Schiffswerft, Germany
Delivered: 1 August, 2001
Deadweight: 28,100 tons
Overall Length: 166.30 m
Beam: 24.75 m
Draft: 10.40 m
Depth: 14.00 m
Engine: 4 stroke, 7300 kW output
Propeller: Lips Controllable Pitch 4,900 mm diameter with a 3C13 hub
Classed by: Germanischer Lloyd

On 19 January 2004 the M/V Rocknes hit an underwater rock in Vatlestraumen near Bergen, Norway. She had just left port a few minutes ago. The vessel was loaded with rocks and pebbles that were to be delivered to Emden, Germany. The vessel was specially designed for dumping rocks offshore that secure underwater oil pipelines.

The underwater rock tore the hull open and water flooded the ballast tanks. The ship then developed a list and in minutes had completely capsized.

The capsizing was extremely quick. Under normal circumstances the ship should not have capsized so quickly. During loading the ship with rocks the conveyor was not able to reach the other side of the rock storage tank. Therefore the ship was not symmetrically loaded. It was heavier on one side. When she hit the underwater rock and water began flooding the ballast tanks causing the list, the rocks in the hold shifted, adding even more momentum which then capsized the ship extremely quickly.

Most ports, especially the larger ones, have a pilot who boards the ship and directs the captain during berthing and when the ship leaves the port. The pilot then leaves the ship by jumping on to his smaller vessel as the ship heads for the open seas.

On this day the pilot Vermund Halhjem, 41, had directed the ship over an underwater rock. The ship’s draft of 10.4 m was too deep and she scraped over the rock. The impact registered as 3 powerful measurements on the seismograph at the Geophysical Institute of Bergen University. A ship with such a large momentum does not bounce off the rock, instead the rock tore the hull open, flooding the ballast tanks.

New maps had just recently been issued by the state’s mapping agency Statens Kartverk showing the position of the rock. The previous version of the map did not show the rock. However the pilot was not informed of this and was found to be not responsible for the mishap.

The ship’s 30 crew included 24 Filipinos, 3 Dutch, 2 Norwegians, 1 German and the pilot who was not part of the crew. Of the 30 crew, 18 died including the Norwegian captain, the German and 16 Filipinos. There were 3 crew members who were trapped in the engine room of the overturned ship. A small diameter hole was drilled on the overturned hull to allow trapped air to escape. A square hole was then cut in the hull and the 3 men were rescued after almost 7 hours of being trapped in the overturned ship. The hole was then quickly sealed by welding a metal plate to the hull. The rescuers were worried that the ship would immediately sink once the air escaped the hull, taking down with her these 3 men.

The ship was later salvaged. This is reported at the following website:
RocknesSalvage.com

According to the BBC World for International Migration Day, the top three largest migrant groups in order of size are:
1) Chinese
2) Indians
3) Filipinos

The Rocknes was floating with the currents and needed to be stabilized before it was possible to rescue the 3 men who were trapped in the engine room.

Tear in the hull of the Rocknes after she hit an underwater rock.

Breakwaters

2006-12-16T00:17:00.000+08:00

There are 3 common types of breakwaters being:
1) Tetrapod
2) Tribar
3) Dolos

There are other variations but these are the most common.

The 3 common breakwaters being Tetrapod, Tribar and Dolos.

They are made of concrete and precast in steel moulds.

Breakwaters.

The breakwater for the Palm Islands in the United Arab Emirates were not of the precast concrete type but blasted quarry rocks. This is less expensive and faster to make. It is also easier to place the rocks by using excavators. If Dolosse had been used, there may be a problem with placing them quickly.

The original post for the Palm Island construction can be found here.

Palm Jumeirah showing the 2 discontinuities in the breakwater to prevent water stagnation.

One of the 2 bridges which was constructed over the discontinuity in the breakwater.

The photo above shows the bridge over the discontinuity in the breakwater. There are 2 of these discontinuities for Palm Jumeirah. The purpose is to allow the seawater to flow around the prime real estate. Stagnant water can be a problem. As construction was required to commence quickly, there was no time for hydraulic model testing and it was not discovered that the water would be stagnant until the breakwater had been constructed.

Commercial Timber Structures (Part 2)

2006-12-06T12:50:00.000+08:00

Big Potato Restaurant, South Australia.

Glulam beams for the Big Potato Restaurant, South Australia.

The Big Potato restaurant in South Australia was engineered by Connell Wagner Pty. Ltd. Another photo of the roof structure before the plywood (or LVL) roof was installed can be seen here.

The central pyramid is acrylic, possibly similar to the Okinawa Churaumi aquarium. It's purpose is to let in sunlight. Acrylic does not shatter like glass as it is a plastic product.

Information centre at Toolangi, Victoria, Australia, showing braced columns.

Double member trusses.

Double member trusses installed.

For the double member trusses above, a metal splice is inserted at each joint followed by the bolts and large washers.

Okinawa Churaumi Aquarium

2006-12-03T10:00:00.000+08:00

The Okinawa Churaumi Aquarium in Japan is the world's second largest aquarium. The world's largest aquarium is in Georgia, USA. The tank which is shown below is 35 m long, 27 m wide, 10 m deep and holds 3 whale sharks.

Large viewing tank at the Okinawa Churaumi aquarium.

The viewing acrylic consists of 7 panels.

Water is drawn with pumps from the East China Sea which then passes through sand filters before flowing into the tanks. The sand filters can be backwashed to keep them clean. Three quarters of the water is recycled and the remaining quarter is pumped out to sea. There are corals in the tank which produce spores. The coral spores in the water is also pumped back out to sea which is good for the environment.

The viewing panel is made from many layers of acrylic manufactured by Nippura Co., Ltd. The acrylic panel is the world's largest measuring 22.5 m long × 8.2 m high × 60 cm thick. Acrylic is highly flammable and during the cutting process water was continuously sprayed to keep it cool. There are 7 panels which were transported from the manufacturing facility to the aquarium. The panels were then placed in position, glued together and baked to form the large continuous viewing screen which weighs a massive 134 tonnes. The adhesive was also designed by Nippura.

As Japan is very prone to earthquakes, the tank sits on its own foundation separate from the rest of the building structure. This provides more flexibility during an earthquake. The acrylic is resistant to earthquakes whereas glass would shatter.

Precast concrete roof beams supporting the skylights.

Point Loads from Beams

2006-12-01T04:32:00.002+08:00

In a reinforced concrete framed building, the suspended beams and slabs are cast monolithically so that there is no weak joint at the beam slab interface.

The picture below shows the beams only for an RC beam and slab system. In loading, the secondary beam is assumed to sit on the two primary beams. Therefore the secondary beam has to be loaded first. The two support reactions from the secondary beam (left and right) are taken as point loads acting onto the primary beam.

Primary and secondary beams in an RC beam system (click to enlarge).

The structural analysis software will automatically factor the loading. Loading input into the software has to be unfactored.

In Malaysia, the reinforced concrete code used is BS 8110 and the load factors are:
Design Load = 1.4 G_k + 1.6 Q_k

where G_k is the Dead Load and Q_k is the Live Load.

The United Kingdom will be transitioning from BS 8110 to Eurocode 2 (EC 2). The original date set for the full implementation of EC 2 in the U.K. has been shifted from 2006 to 2008 and then it was shifted again to 2010. In the ISO-TC 71 – Concrete, Reinforced Concrete and Prestressed Concrete meeting in Istanbul in September 2004, which was attended by the author representing Malaysia, EC 2 has been accepted as to comply with ISO standards.

Commercial Timber Structures (Part 1)

2006-12-01T03:29:00.000+08:00

Timber used for an atrium in a shopping centre. The parallel chord trusses have bolted connections.

Pinus radiata glulam beams used for this shopping arcade.

The original Ettamogah Pub in Australia is located 10 km north of Albury, NSW, just off the Hume Highway, along the NSW and Victorian border. It was built in 1987 and is a true replica of Ken Maynard's cartoon series made famous in the Australian and New Zealand Post Magazines during the 1950s while he was working as a traffic policeman in Melbourne. Ken is the creator of "The Ettamogah Mob" and also "Ned and his Neddy".

In 1994 the Ettamogah Group was founded and commenced establishing pubs and restaurants throughout Australia. The Group is also one of the latest teams to join Formula Ford Racing with an Australian built race car and transporter.

Ken Maynard's Ettamogah Pub.

The photo below shows a pair of crane truss runways being supported on each side of the timber glulam columns. It is very usual because the runways are steel but the columns are timber. The self-weight of the crane truss would be quite heavy.

Crane truss runways supported by glulam columns.

Crane truss on steel runways which are supported by timber columns.

Portal Frames

2006-11-29T23:24:00.000+08:00

Below is an A-frame. As it has a low roof height near the supports, it is good for storing materials such as in warehouses.

A-Frames.

Portal frame with deep rafters.

The Ron Brierely hangar in Wellington, New Zealand looks like an aluminium structure from the outside.

Ron Brierely Hangar, Wellington, New Zealand.

But once inside it is discovered that the aluminium or zinc walls and roof are supported by Laminated Veneer Lumber (LVL) portal frames.

Inside the Ron Brierely Hangar.

Glulam portal frames for a swimming pool complex.

Substantial portal frames for a building in Switzerland.

Strong knee joints have been designed for these portal frames for a building near the Swiss alps.

Hidden roof trusses designed for Malaysian buildings look something like what can be seen here. The false ceiling would be suspended from the bottom chord of the triangular roof trusses, above which, the trusses are hidden under the roof tiles. Spacing between each timber truss is approximately 600 mm centre to centre.

The Palm Islands, UAE

2006-11-28T09:17:00.001+08:00

The Palm Islands, off the coast of Dubai, United Arab Emirates, are known as the Eighth Wonder of the World. The first to be constructed was The Palm Jumeirah. The Palm Islands were constructed with natural materials only. The foundations are sand which was dredged from the sea. It was found that desert sand was not suitable. Dredges dredged sand from the Persian Gulf and using GPS the sand was sprayed to form the islands in a process called rainbowing.

To prevent erosion of the sand islands, a large breakwater was constructed using quarry blasted rocks. The breakwater stands 3 m high above the water. Finer material is in the core while the heavier rocks form the armour.

The Palm. On the right is The World, islands arranged like the continents of the world.

During construction it was discovered that water was stagnant inside the breakwater. There was no model hydraulic testing before construction and therefore it was not known that this would happen. The breakwater was then broken up in 2 areas near the shore, facing away from the waves. Bridges were constructed across the break. The break allowed water to flow into the palm islands and prevent stagnation while preventing waves from getting in.

Constructing infrastructure and structures on the sand islands.

The World is the brainchild of Crown Prince of Dubai His Highness Sheikh Mohammed Bin Rashid Al Maktoum. Located at 55^o East Longitude & 25^o North Latitude, it consists of 300 islands placed in the shape of the continents of the world.

Rainbowing.

The break in the breakwater can be seen near the top of the photo.

David Beckham has bought property on The Palm. After construction started on The Palm Jumeirah, it was decided to build two more, The Palm Jebel Ali and The Palm Deira. The Palm Deira is larger than Paris. The Crown Prince then also asked for The World to be constructed.

Tricolor & Asian Hercules II

2006-11-27T05:34:00.000+08:00

This post shows a photo of the ro-ro vessel Tricolor which is being loaded with glulam timber arches (please click here). The photo is from Dr. Alex Heaney and Dr. Peter Kneen of UNSW, Australia.

The Tricolor was built in 1987 by Tsuneishi Corporation of Japan. It was then registered in Tønsberg, Norway and owned by Capital Bank, Scotland.

The MV Tricolor, before her sinking on 14 December 2002.

On Saturday, 14 December 2002, at 02:15, the car carrier Tricolor and the container vessel Kariba collided. The Tricolor was travelling from Zeebrugge to Southampton. The Kariba originated from Antwerp and was en route to Le Havre. The collision occurred when both vessels were about to enter into the north-south shipping route through the English Channel.

The Kariba struck the Tricolor on the port side. The car carrier quickly took on water, capsized and sunk within 30 minutes. The crew from the Kariba rescued three of the Tricolor's crewmembers. The remaining 21 crewmembers found refuge on board the Belgian URS tug Boxer.

Two days later, on 16 December, the unloaded German cargo vessel Nicola struck the wreck of the Tricolor. Tugs pulled the cargo ship from the wreck on the same day. On Wednesday, 1 January 2003, the Tricolor was struck again. This time, the Turkish tanker Vicky, which was carrying 77,000 tons of gas oil, hit the wreck.

The cargo of 2,871 new cars, mostly from premium German and Swedish manufacturers including BMWs and Volvos, worth £30m (representing a retail value of £60m), were removed from the wreck and destroyed. Most oil was removed from the ship's tanks soon after it sank, but during the salvage there was a small 540 tonne oil spill, sparking concern.

The damaged container vessel Kariba.

The reason that the Tricolor sank so quickly was because she was a ro-ro (roll-on roll-off) vessel. Ro-ro vessels are made to carry vehicles on the bottom deck and therefore there is no partitioning with watertight doors. Once water enters, the bottom deck floods extremely quickly. The Estonia was also a ro-ro vessel. She sank on 28 September 1994 due to a broken bow visor which allowed water to flood the car deck causing the loss of 852 lives including crew and passengers. The Express Samina was also a ro-ro ferry which sank on 26 September 2000 after hitting rocks off the coast of the Aegean island of Paros. Eighty of the over 500 passengers were lost at sea.

The Asian Hercules II was used to lift the Tricolor in the salvage operations. The following website, Tricolor Salvage 2004, documents the methods used to salvage the Tricolor from the ocean floor.

Asian Hercules II waiting to lift the Tricolor.

The Tricolor was a write-off.

The Asian Hercules II lifts cut segments of the Tricolor as it was too heavy to be lifted in one piece.

The Asian Hercules was used to lift the container handling crane from the barge to the container berth at Kuantan Port. The post and photos of the container handling crane can be found here.

The Asian Hercules which was used at Kuantan Port has a 1,600 metric tonne lifting capacity while the Asian Hercules II shown above has a 3,200 metric tonne lifting capacity, which is twice the Asian Hercules. I did not have my camera with me and missed the opportunity to photograph the Asian Hercules but it looked something like the Asian Hercules II shown above. More photos can be found at the Tricolor Salvage 2004 website.

Post-Processing

2006-11-26T06:02:00.003+08:00

The relationship between the bending moment diagram (BMD) and shear force diagram (SFD) is as follows:

This means that the first derivative of the BMD is the SFD. This explains why at the point of maximum bending moment the shear force is zero. At maximum bending moment the slope of the BMD is zero.

A single span beam is known as a determinate beam. By using maths it's possible to solve for both the reactions, the BMD and the SFD exactly. A continuous beam is known as an indeterminate beam. It is not possible to solve for the reactions, the BMD and SFD for an indeterminate beam.

Single span and continuous beams.

Topcad post-processes with 10 values of BMD and SFD for each beam span. I worked at the structural engineering consultancy firm, Struc Plus, in April 2001. This company was located at Menara Mutiara Majestic, PJ Old Town. They have since shifted elsewhere. Struc Plus is an Australian company. The software Struc Plus is used as a plug-in in the AutoCAD for assistance with engineering drawings such as beams, slabs, connections, etc.

The continuous beam and subframe analysis software which I used at Struc Plus was WinSTRUC by the Bonacci Group of Australia.

WinSTRUC is much newer than Topcad and runs under Microsoft Windows. It is also copy protected like most civil engineering software. Unlike Topcad, WinSTRUC varies the number of nodes for calculating the BMD and SFD for each beam span in its post-processing. The number of nodes depends on the beam length. The longer the span, the more the nodes. This improves accuracy. I think around 15 nodes may be used for longer spans, which is higher than Topcad's 10 nodes.

Post-processing a simply supported beam.

In post-processing the support reactions are calculated first.
Clockwise direction is taken as positive.
Σ M_B = 0:
5 R_A – 20 × 1.4 = 0
R_A = 5.6 kN ↑
Σ M_A = 0:
20 × 3.6 – 5 R_B = 0
R_B = 14.4 kN ↑

The maximum bending moment will be under the 20 kN point load.
M_max = R_A × 3.6 = 5.6 × 3.6 = 20.16 kNm
or
M_max = R_B × 1.4 = 14.4 × 1.4 = 20.16 kNm

Note that the BMD diagram is upside down. Positive moment is below the axis and negative moment is above the axis. Positive moment is also known as sagging moment while negative moment is known as hogging moment.

The SFD shows maximum shear at the supports with 5.6 kN and 14.4 kN being the left and right support reactions respectively. Also 5.6 + 14.4 = 20 kN, the value of the point load.

Examples of bracing by Prof. Julius Natterer.

Tapered rafters for portal frames.

The photo above shows tapered rafters for the portal frames.

Timber Domes

2006-11-15T17:27:00.001+08:00

This is a large ribbed dome with a circular section in the middle to support a concentrated load. A concentrated load is also known as a point load.

Large ribbed dome with piece in the middle for supporting a point load.

An example of a point load is the load from the beam support onto another beam below. In a reinforced concrete structure there are primary beams, secondary beams, tertiary beams and so on. The primary beam is the lowest beam. The primary beam resists the loading from the secondary beam while the secondary beam resists the loading from the tertiary beam and so on. By looking at the floor plan of the structural drawing it is possible to see which beam is secondary and which is primary. Load calculation must be performed first for the tertiary beam, and then the secondary beam, and then the primary beam, which is always loaded last. The primary beam is usually attached to the columns.

A simply supported beam has one span. Continuous beams have two or more spans. Every beam span has two supports, at the left and at the right. For a secondary beam which is supported by two primary beams (which due to geometry would usually have to be two different beams), the two supports of the secondary beam will place a point load onto each of the two primary beams below it.

In Civil Engineering there is a difference between the terms Analysis and Design as follows:

Structural Analysis is the analysis of the structure, whether it is a beam, column, slab, retaining wall or some other structure primarily for bending moment and shear force. In some cases analysis for torsion is also required. However, for a reinforced concrete building frame, torsion is usually ignored. For the large advertising billboards which can be seen by the highways, the steel post should be analysed for torsion caused by wind loading. Structural Analysis is usually performed by using computer programs.

Structural Design is done only after Structural Analysis has been completed and the results from the bending moment and shear force are known. In structural design, the members are sized and the steel reinforcement designed.

The general term "Design" is often used to refer to both Structural Analysis and Structural Design.

The following is an example of the process of designing a reinforced concrete beam:

The beams are placed at the appropriate locations in accordance with the Architectural drawings.
Preliminary sizing of the beams. This will be guesswork. If the section size is later found to be inadequate, the beam will have to be enlarged.
Calculating the load carried by the beams. The beams carry dead load and live load. The dead load consists of the beam self-weight, slab, floor finishing, partitions, brick walls and accessories such as air-conditioning and piping. The live load (also known as the imposed load) is taken from the British Standards, for example the live load for domestic dwellings is 1.5 kN/m² and for dance halls and gymnasia it is 5.0 kN/m². Live load is applied to floors and the roof.
The beams are analyzed using computer software to obtain the bending moment diagram (BMD) and shear force diagram (SFD). The software will also give the left and right support reactions for each beam span.
If the beam size is adequate, it is now possible to design the beam reinforcement for bending and for shear.
The beam is then detailed as a structural drawing.

Glulam central column for hot spring baths.

Outside view of the free-form shelter over the hot spring baths.

Design is a top down approach. The roof trusses are designed first followed by the roof beams. The floor slabs are designed before the floor beams because the beams support the slabs. If the beams are designed first and it is later discovered that the slabs are not thick enough, the beams will have to be redesigned to support the thickened and heavier slab.

There are 3 load types for input into the structural analysis software:

1) Uniformly Distributed Loads (UDL) ― The beam self-weight is a UDL. The load is constant throughout the beam length and does not vary unless the beam is non-rectangular. A 130 mm wide × 600 mm deep RC beam has an unfactored self-weight of:
24 kN/m³ × 0.13 × 0.6 = 1.872 kN/m
In design the concrete density is taken as 24 kN/m³. It is assumed that the whole cross-section is concrete. Reinforcing steel has a density of 77 kN/m³but during load calculation the weight of steel is not known yet.

2) Triangular / Trapezoidal Loads, and

3) Point Loads

BMD and SFD for a simply supported beam carrying a UDL.

The diagram above shows a one span simply supported beam carrying UDL. The BMD is parabolic with the maximum bending moment at midspan. This maximum value will be used as the design bending moment for the whole beam. The SFD shows maximum shear at the supports. For this symmetrical loading, both left and right shear forces are equal. The maximum shear force at the supports equal the support reactions. At the location of maximum bending moment the shear force is zero.

During 1994-95 I used the computer program Topcad for the analysis and design of continous reinforced concrete beams. After the loading had been keyed in, the program analyses the continuous beam and plots the BMD and SFD. It then continues to design the reinforcement. This is shown in colour graphics on the monitor. The beam details can then be exported to a DXF file for importing directly into AutoCAD. I used Topcad during my employment at Perunding Delima which is an engineering consultancy firm in Taman Tun Dr. Ismail. The good thing about Topcad is that the computer did everything. Engineers were not required to draft the beam details. All that was required was to calculate the loading from the structural drawings and then input the data into Topcad.

Topcad runs under MS-DOS. In those days there was no Windows XP. The computer was a 486DX2-66, which was the best at that time. A very nice postscript Canon laser printer was attached to it. Topcad, like most other structural engineering software which I have used, is copy protected. You need to attach a dongle to the LPT printer port or it won't do anything. The program runs directly from a 3.5" 1.44 MB floppy disk although you can copy it to the hard drive. Programs were so small and compact in those days!

Large grid dome.

In the photo above it is stated that splices are used for transfering forces. From looking at the picture, splices have not been used at every intersection possibly because this would be time consuming and expensive to construct. From what can be seen, splices have been used at selected intersection points to improve stiffness.

Interior of the cupola of the Deutsch-Ordens-Spitals in Friesach, Karnten.

Exterior of the cupola of the Deutsch-Ordens-Spitals in Friesach, Karnten.

Timber Arches (Part 3)

2006-11-12T19:00:00.000+08:00

The following is a sketch of two long span glulam timber arches used for a roof.

Sketch of an arch roof by Julius Natterer, Switzerland.

The half span portal frames below will be lifted by crane and joined at midspan to make a complete portal frame. The purlins are braced for extra strength.

By using an arch shape, either circular, parabolic or some other function or shape, the bending moment is reduced at midspan. For a uniformly distributed dead load and live load, the sagging bending moment will be maximum at midspan. By having a connection at the midspan, the strength could be reduced here. Fortunately the steel connection, such as the gusset plate at the midspan happens to be stronger than the timber material of the arch. The steel bolts or dowels are also stronger than the timber. The timber at midspan has to be checked for shear resistance to the loading from the bolts or dowels.

Half span portal frames waiting for lifting and joining at midspan.

Timber Arches (Part 2)

2006-11-12T05:04:00.000+08:00

The portal frame below shows purlins above the knee and girts below the knee.

Purlins and girts attached to the portal frames.

Bracing on large span arches.

In the photo below, the purlins are parallel chord trusses with TMPC connections.

Glulam half arches with parallel chord trusses as purlins.

Glulam arches for a swimming pool.

Three pin catenary structure on concrete supports.

Timber Arches (Part 1)

2006-11-08T00:46:00.000+08:00

Glulam constant curvature arches are being loaded into a roll-on roll-off (RO-RO) vessel below. A RO-RO vessel is a car and passenger ferry. Vehicles park on the bottom deck while passengers use the upper decks. Vehicles are able to drive directly on and off the ferry and hence the term RO-RO.

Loading glulam arches into a RORO vessel.

This revives memories of the tragic events of the M/S Estonia disaster which occurred on 28 September 1994. The Estonia was on her way from Tallinn, Estonia to Stockholm, Sweden carrying 989 passengers and crew. At 0115 the bow visor broke off due to constant pounding from the waves. The ramp behind the visor was pulled fully open allowing large amounts of water to flood the car deck. As there are no separate compartments in the car deck, the entire deck flooded extremely quickly. The ship listed starboard and during the final stages before sinking the list was more than 90 degrees. The Estonia sank in 35 minutes after the bow visor had broken off. It sank upside down, stern first. The tragedy claimed 852 lives including all the officers on the bridge who heroically went down with her.

Attaching hangers to the glulam arches.

The hangers above can be used to support the false ceiling, lighting fixtures, air-conditioning ducts, etc. The arches are half arches with a moment connection at the apex.

Three-pin arch with straight segments.

The midspan connection is again a moment connection. A pinned connection cannot be used at midspan as this would place alot of stress on the column foundations. If the supports at the base of the columns are also pinned, there would be rotation and a high possibility of collapse.

Two half arches for each arch. As the arch gets higher, the load changes from bending moment to axial compression along the arch member.

Variable curvature crossed arches for a sports stadium in New Zealand.

Base of glulam arch.

The laminas are very thin. This allows for smaller radius curvatures.

Low profile arches.

These low profile arches would carry more bending moment than an arch which is high. Deeper members are more efficient in resisting bending moment than wide members.

Three-pinned arches with concrete pedestals to resist horizontal thrust.

Glulam (Part 6)

2006-11-04T01:45:00.000+08:00

A marquee made from glulam.

Glulam marquee.

Curved glulam roof.

Timber pedestrian bridge.

The curved beams supporting the deck would be glulam.

Glulam portal frames.

The cardboard wrapping protects the timber from damage.

Glulam roof for an aquatic centre.

Factory building.

Hardware shop.

NFL stadium.

Glulam roof beams inside the NFL stadium.

Glulam (Part 5)

2006-10-30T21:45:00.000+08:00

Here are some more photos showing the use of glulam.

Glulam in a church.

Glulam roof beams in another church.

Glulam roof beams also used in this church.

Notice that the glulam beams are jutting out below the false ceiling.

The boats below are constructed from glulam which allow for the curves required.

Glulam boats.

The photo below looks like a holiday resort or a hotel lobby of some sort.

Glulam roof and timber flooring.

Curvy glulam roof for the same building as shown in the previous photo.

Glulam roof with non-parallel chord glulam trusses.

Very high glulam portal frames.

Glulam roof bracing.

The ceiling fans are installed very high in the photo above.

Normal timber roof trusses.

The trusses in the photo above look like normal timber trusses, not glulam. The bottom tension chord is made of two members but the top chord is only one member. There are no gusset plates and bolts cannot be seen so nails were probably used.

Glulam roof beams jutting out below the false ceiling.

Glulam roof trusses. Possibly a hotel lobby.

Glulam (Part 4)

2006-10-30T00:15:00.000+08:00

Although glulam can be cambered, it can also be used as straight members. The photo below shows glulam trusses in a library. Gusset plates and possibly bolts are used as the connections. The bottom chord is likely to be twin members with gussets on both sides.

Glulam timber trusses in a library.

The photo below shows glulam portal frames with arched rafters.

Glulam arched portal frames.

Glulam in a foyer.

Glulam rafters and purlins.

Concrete columns support glulam rafters and purlins in the photo above.

Glulam columns.

In the photo above, glulam columns have been erected. The RC slab BRC is in the foreground.

Glulam portal frames.

The cherry picker is used to install purlins to the glulam portal frames in the photo above.

Glulam in a hall / indoor recreation area.

Glulam portal frames and purlins for a hardware store.

Glulam used for rafters and purlins.

Glulam columns and beams for a mattress retail store.

Glulam roof structure.

Glulam internal roof trusses.

Long span glulam beams for an indoor swimming pool provides column free space.

Glulam roof, possibly at a holiday resort.

Glulam (Part 3)

2006-10-27T06:23:00.001+08:00

The laminas are stressed when they are curved. Thin laminas are used for smaller radius curvatures. The stresses due to curvature will also cause strains in each lamina.

Stresses and strains are formed in the laminae due to curvature.

The photo below shows a glulam truss which isn't curved. Splices were used to connect the truss elements together. The support is a bearing pad similar to those found under bridges.

Glulam timber truss with splice connections.

Laminated Veneer Lumber (LVL) is like glued laminated timber but the individual veneers are much thinner, typically only 2.5-3.2 mm thick. The grain of the veneers are all oriented parallel to the sheet lengths only. This is unlike plywood where the grain is oriented as cross-plies alternately for each layer. Plywood can be used for formwork. The formwork for the suspended RC slab base are usually plywood boards.

Laminated Veneer Lumber (LVL). Click on images to enlarge.

The Glued Laminated Timber Association of Australia (GLTAA) sets industry standards and implements a code of practice and policing policy in order to add credibility to the product and to those manufacturers who are approved as members.

Regarding the use of glulam as a structural element similar to steel, the GLTAA website states the following about corrosive environments. Steel has the ability to corrode while timber may decompose under high moisture content. Timber may also be subjected to termite attacks.

Corrosive Environment

Timber is non-corrosive material and therefore should be considered a primary choice structural material for buildings either located in a corrosive environment such as along a coastline, or enclosing a corrosive environment, such as fertiliser and chemical stores, swimming pool enclosures and reservoirs.

Timber does not require corrosive treatment in these environments, however, in environments in which there is high humidity and/or condensation, such as swimming pool enclosures and reservoirs, moisture exclusion surface coatings are needed.

With regard to the fire rating of glulam, the GLTAA website states the following:

Fire Ratings

In a fire, glulam has an inherent fire rating. As timber burns, a layer of charcoal forms enclosing a core of timber, which is yet unaffected. The timber core maintains its structural capacity. Hence, dependent upon the loss of material to the charcoal layer, glulam can remain structurally adequate to carry the dead load of the structure for a period of time. The thickness of the charcoal layer is proportional to the length of time of the fire. At some point, the remaining structurally sound timber core will be unable to restrain the applied loads and the glulam member will collapse. The time required for the fire to burn enough timber thickness to reach the collapse point is deemed the fire rating of the glulam member.

In recognition of this property of timber, design standards have been produced for designers to assess member sizes required for the desired fire rating.

In general, it is significantly cheaper to increase the dimensions of glulam slightly in order to provide the required fire rating, than to enclose the member in fire resistant material. This property should make glulam the primary choice material in buildings requiring structural members to have a fire rating.

The photo below shows a moment connection for the base of a glulam column. This is unlike the pinned connection which was shown in a previous post. The pinned connection allows for rotation which means that the bending moment is zero parallel to the direction of rotation. The benefit of the pinned connection is that it will reduce the stresses at the support to mainly axial compression. Small amounts of bending moment due to the effective length of the column and eccentricities of axial loading may occur but these are usually much less than the bending moment which occurs due to the dead load, live load, wind load or seismic load.

Moment connection at the base of a glulam column.

For biaxial bending, the larger bending moment should be parallel to the column's longer dimension. As usual, both the x and y directions should be checked to ensure that the column can resist the biaxial bending moment in these two directions as well as the axial compression.

Glulam structural frame.

Although the members are straight, the structural frame above has been made entirely of glulam members.

Glulam (Part 2)

2006-10-24T05:10:00.000+08:00

Finger jointing can be used to join two pieces of glulam together. Glue is then used to fix the two joints together. The photos below show a small gap at the end of each tooth to allow the glue to compress and set. It is stated that end jointing of timber is very difficult and not very reliable.

End finger jointing glulam pieces.

The photo below shows a straight glulam beam where the individual laminas have been glued together. Each lamina is about 50 mm thick. The laminas can be thicker because the beam is straight, and not cambered.

During service, the beam would be loaded downwards with the deeper dimension being vertical. Deep beams are more efficient for resisting bending moment. This is why I-beams are deep but very thin especially along the web.

Straight glulam beam.

Below is a finger jointed wall structure. Short individual timber elements are finger jointed and glued together to form longer lengths.

Finger jointed wall structure.

The glulam portal frame allows for curved geometry. There are no knee joints which require gussets and bolting. For the half-arch glulam portal, there is only one connection at the apex.

Half-arch glulam portal frames.

Half-arch glulam portal frames joined together at the apex. There are no knee joints.

Doubly-curved glulam half-arch portal frames.

The picture above shows doubly-curved half arched glulam portal frames used for an exhibition centre. To save on electricity, skylights provide natural lighting during the day. Floodlights provide lighting at night. The ceiling space is very high, providing good ventilation.

Glulam (Part 1)

2006-10-18T03:35:00.000+08:00

For manufacturing glulam beams, various adhesives can be used. The glue ensures that there is high strength and a rigid bond and that the laminates permanently act as a single unit.

Stronger glues such as urea formaldehyde (1937) and now other modern synthetic resins like resorcinol are suitable for exterior use.

Adhesives for glued laminated construction.

The Australian Graduate School of Management (AGSM) at The University of New South Wales (UNSW), Australia uses glulam beams as cantilever columns and pergola supports.

Glulam beam production. The beam has a slight camber.

The laminas of the glued laminated beam are pressed together hydraulically in a factory. Here three beams are pressed simultaneously. Thicker laminas are used because the beam is generally quite straight.

Glulam beam with double S-shaped curve.

The glulam beam in the photo above has four curves along its length.

Transporting the glulam arches by truck.

In the photo above, 4 glulam arches are transported to the Lillehammer Olympics site by truck. There is no semi-trailer as the arches are oversized. A follower wheeled bogey is used as the rear wheels. Preservatives were probably applied to the timber to prevent rotting and termite attack.

Large indoor aquatic centre.

The water slide is attached to the timber beams in this aquatic centre. The timber beams have a long span and are column free above the swimming pool.

Curved glulam in a restaurant.

The curved glulam used for this restaurant are very architecturally pleasing. Almost every beam and column is curved.

Glulam roof for Big Potato restaurant.

The glulam roof for this Big Potato restaurant allows for column free space inside.

Connectors and Glulam

2006-10-17T04:19:00.000+08:00

The picture below shows the difference between a bulldog connector and a toothed connector. The toothed connector is hollow at the centre with only a ring of teeth at the circumference. The bulldog connector is more solid.

Top Left: Bulldog connector.
Top right: Toothed connector.
Bottom: Toothed connectors inside a softwood glued laminated beam.

A glued laminated (glulam) beam is made up of many layers of laminas. The laminas may be any thickness, but usually 19 or 35 mm, and occasionally up to a maximum of 50 mm, are glued together under factory conditions to form structural members of any size and length. Larger laminates up to 50 mm which have fewer glued surfaces are generally more economical. The thinner 12 and 19 mm laminates can be used for sharper curvatures.

Adding attachments to the glulam beams.

As can be seen in the photo above, the glued laminated beam is cambered. The timber grains run parallel to the beam length.

The arch bridge beam support is a single steel pin.

The glulam beams were used for a timber arch bridge. The support for the arches was just one steel pin.

Pin joints were used for this roof structure.

Pin joints were used for the roof structure shown above. The columns are concrete.

Glulam used in a swimming pool foyer.

Glulam beams were used in the foyer of this swimming pool complex. Thinner laminas should be used for tighter curvatures. Again the column is supported on only one steel pin. This pin allows for rotation and therefore the bending moment at this point is zero. The glulam column has to resist axial compression only at the support.

Staggered pattern of dowels for this moment connection to reduce splitting.

Circular pattern of dowels for these portal frame knee joints.

A circular pattern of dowels were used for these portal frame knee joints for an equestrian arena. The dowels have to be designed for both bending and shear. For the moment calculations, the centre of rotation of the dowels can be taken as the centre of the circle.

Splices, Bolts, Split Ring and Bulldog Connectors

2006-10-08T01:29:00.000+08:00

While TMPCs and gusset plates are designed to be seen, splices are usually hidden inside the timber member. The metal splice is placed inside a slit along the cross-section of the timber member. Bolts or dowels then secure the splice in place.

Hidden metal tension splice.

The hidden splice is also protected from fire and corrosion.

Steel is very susceptible to fire. It deforms very quickly under heat which is why most steel I-beams and steel columns are fireproofed. If the building has a steel frame rather than a reinforced concrete frame, if you have a look at the columns and beams you may see a rough grey coating on them, something like shotcrete. This is the fireproofing. Reinforced concrete lasts longer in fires than steel. Steel warps and buckles very quickly under heat, trapping the inhabitants of the building inside.

These are timber splices, on the insides of the trusses.

The photo above shows timber splices rather than steel. They are on the insides of the bottom chord of the trusses. The bottom chord is made of two members allowing the splices to be bolted in between the two members.

6 splices along the cross-section for a Lillehammer Olympic structure.

The photo above shows 6 steel splices for a Lillehammer Olympic structure in Norway. They are at an angle so that the connecting members can be joined at an angle rather than at 90 degrees. Lillehammer hosted the 1994 Winter Olympic Games.

A steel tee splice.

The photo above shows a very well hidden steel tee splice. The dowels are very small and aesthetically pleasing.

A very nice looking ceiling possibly using 4-way splices.

Four sided splices, looking like a cross, were probably used for the ceiling in the picture above. The skylights provide natural lighting.

Bolts and gussets are used for these large roof trusses in this pub.

These large trusses in this pub uses bolts and gussets. The picture does say that the gussets are splices but I thought splices are usually hidden in the timber. The bottom chord has been strengthened with 3 members along the cross-section. The bolts and gussets compress all 3 members together. The web members look to be made of double members separated with timber spacer blocks. The web members would be the same width as the bottom chord members.

Splices in the roof of a fish & chips restaurant in Auckland, New Zealand.

The splices are nicely hidden inside the timber members of this curved beam roof of a fish & chips restaurant in Auckland, New Zealand.

An 8 member splice connection.

Bolts and Bulldog Connectors.

Douglas Fir is an Australian timber species. The Bulldog Connector is possibly something like a washer, but with teeth, giving good grip in shear.

Split ring connectors (SRC).

Split ring connectors (SRC) have larger capacities than bolts. They are often used for larger truss connections, truss bridges and towers. They may eliminate the need for notches and plates and therefore reduce costs. The rings are forced into a groove which has been cut into the pair of adjoining faces using a special tool. The split in the ring allows the ring to be opened and forced into position. Unfortunately the ring reduces the net cross-sectional area of the timber members, which may be a problem with tension members.

Bolts and gusset connections.

Bolts, square washers and angles.

In the picture above, the angles have been strengthened with a perpendicular plate in the middle of the angle. This provides extra stiffness in supporting the perpendicular member.

Gusset Plates

2006-10-01T19:05:00.000+08:00

Instead of using toothed metal plate connectors (TMPCs), gusset plates and nails can be used instead. The portal frames below use plywood gusset plates and steel nails which have been gun-nailed to the portal frame members.

Using gusset plates and nails for the timber portal frames. The rafters are joined to the columns by gusset plates.

Gusset plates at the knee joints of a portal frame.

Gusset plates can resist more bending moment and shear force than TMPCs. In the photo above, gusset plates are used for the portal frame while TMPCs are used for the parallel chord truss purlins which carry a much lighter load than the portal frame.

Gussets used in between two truss members.

In the photo above, gussets are used in between two truss members. There is one gusset at each joint instead of the usual situation where there are two gussets, one at each side of the truss member.

A good thing about gussets is that they can be gun-nailed on site. With TMPCs they are usually hydraulically pressed onto the timber truss in the factory. Therefore the entire timber truss has to be prefabricated in the factory and then delivered to site for installation.

Pest prevention by closing gaps in the gusset.

This gusset has a timber piece at the edge to close the gap and prevent pigeons and other pests from nesting or defecating inside. The gusset can be pre-nailed to the column on site before the column is erected.

A large gusset with many nails.

Gussets used as architectural features.

The gussets in the picture above will be painted and become part of the architectural feature of the building.

Steel gusset plates.

Steel gusset plates are stronger than timber gussets. Here they are nailed onto the two external faces of the timber portal frame. This gusset plate has many nails. There are nail groups on the ends of each member with the joint in between. The portal frame member has to be sufficiently deep to accommodate nails on both sides.

A Trip-L-Grip connection.

A Trip-L-Grip connection can be used to connect perpendicular timber members as shown above. There are 3 steel plates with nails driven into the timber.

Gusset plate connection testing.

In the connection test above, the steel gusset plate has deformed. As the timber is a softer material than steel, the timber should fail first. That's probably what happened as a large chunk of timber is missing.

Gusset plate connection testing with failure occuring in the timber first.

When the ultimate load has been reached, the nails crush the timber. If the loading is increased, the gusset plate begins to deform as shown above.

The Multimedia Filter

2006-09-19T19:17:00.000+08:00

Fibre Reinforced Plastic (FRP) Multimedia Filter.

The FRP Multimedia Filter has several layers of material inside it. This is unlike the FRP Carbon Filter which has only one layer being activated carbon. The FRP Deionising (DI) Filter also has one layer being deionising resin. Deionised water does not conduct electricity. The condition of the water, whether it is ionised or deionised, can be checked by using a conductivity meter such as the Spectech. Two electrodes are located inside the PVC pipe. The battery powered circuit is switched on by toggling a switch. A meter in series detects the current or voltage flowing. If the meter does not deflect then the water is deionised.

Water enters the multimedia filter from the top and flows downwards. It leaves the filter through the central tube. During backwash the flow is reversed. The garnet layer is imported from Australia. The FRP tank can be imported from Structural U.S.A., which is a Pentair Company.

Toothed Metal Plate Connectors (Part 2)

2006-09-19T18:42:00.000+08:00

Toothed Metal Plate Connectors (TMPCs) can be used for residential trusses as shown below. In Australia houses are commonly constructed using timber framing.

Residential roof trusses using TMPCs. The house is constructed by using timber framing.

A hydraulic press can be used to press the TMPCs to the timber trusses.

Hydraulic pressing of the TMPCs.

Manufacturing a prefab timber truss with a hydraulic press.

Timber truss supports.

Two TMPCs from two different manufacturers.

Toothed Metal Plate Connectors (Part 1)

2006-09-18T23:47:00.001+08:00

The following photographs have been taken from a CD-ROM which is titled: "Timber Structures, An Introduction to Limit States Design proposed for AS 1720.1 1997". The package was created using Macromedia Authorware. The program runs from an executable (.exe) file and does not need to be opened by using the Authorware program. The CD-ROM was written by Dr. Alex Heaney and Dr. Peter Kneen from the School of Civil & Environmental Engineering, University of New South Wales, Sydney, Australia.

Toothed Metal Plate Connectors (or TMPCs) can be used to connect timber truss members together instead of using bolts and washers. Gang-Nail is an Australian manufacturer of TMPCs. Toothed Metal Plate Connector is the proper name while Gang-Nail is a trade name.

In Malaysia we call slab reinforcing fabric BRC which is also a trade name.

TMPCs used for timber roof trusses (click on images to enlarge).

The TMPCs are used in pairs, one on each side of the timber roof truss.

The timber truss members have the same thickness so that the TMPCs can be used.

TMPCs used for a timber frame.

In the photo above, the TMPCs have been used to construct a frame for a demountable office.

Parallel chord timber trusses used for the floor.

The brick walls in the photo above are load bearing brick walls which support the timber floor trusses. There would be a strip footing underneath the brick walls. The buttresses give the brick wall lateral stability. This sort of construction is rarely seen in Malaysia as the houses usually have reinforced concrete ground beams and ground slabs. The brick walls in Malaysian building construction are usually non-load bearing.

The cantilever extension was constructed using TMPCs and parallel chord timber trusses.

The strength of the cantilevered balcony shown above is quite amazing. It is supported only by the TMPCs as there are no supports at the left edge.

Manufacturing parallel chord trusses with metal diagonals which have flattened toothed ends.

The timber parallel chord trusses are manufactured with metal diagonals which have flattened toothed ends.

Large span parallel chord trusses using metal diagonals with toothed connectors at the ends.

TMPCs used in a load test for a parallel chord truss.

Illusionary Pictures

2006-05-30T20:02:00.000+08:00

I got these pictures from Pakcu's Blog. They're really amazing. Sit close to your monitor and look at the first one below. On the left is an angry looking face. On the right is a calm picture of a woman. Now walk away from your screen about 4 metres or so. The left picture has become the right picture and the right picture has become the left picture. Amazing! It even works if printed out.

For the 3 pictures below, sit close to your screen and look at them. The pictures look like they're moving slowly.

Water Still

2006-05-27T15:38:00.003+08:00

The made in Malaysia Rynalab Water Still is the same as the imported Merit Water Still W4000.

A water still is also known as a distiller. A distiller can produce pure water, which means pure H2O and nothing else. Mineral water is not pure water as it contains minerals. Mineral water can be produced by using reverse osmosis or multi-stage filtration.

The water still which is made in Malaysia is the Rynalab Water Still. The following are its specifications:

Dimensions: 46.5 cm × 14.5 cm × 43.5 cm (w × d × h)
Weight: +/- 5 kg
Heater: 3 kW chromium plated
Voltage: 220/240 VAC, 50 Hz, single phase
Current: 15 amps
Water Supply: 1 L/minute
Minimum Pressure: 3 psi
Distillate Production: 4 Litres/hour

There is an exact replica of the Rynalab Water Still which is made by Barloworld or Dynalab Corp., USA. This is the Merit Water Still W4000. It also has a distillate output of 4 Litres per hour. As the Merit and Rynalab are exactly the same, it would be cheaper to buy the locally made Rynalab distiller which runs on 240 V.

Hill-Site Development

2006-05-21T00:02:00.000+08:00

The talk entitled “The Engineering Aspects of Hill-Site Development” was presented by Ir. Dr. Gue See Sew on Thursday, 19 February 2004 at the IEM Conference Hall, 2nd floor, The Institution of Engineers, Malaysia in Petaling Jaya, Selangor. The talk began at 5.30 p.m. and ended at 7.00 p.m.

Ir. Dr. Gue is the Managing Director of Gue & Partners Sdn. Bhd. He holds a PhD in Geotechnical Engineering from Oxford University. He was the President of the Institution of Engineers, Malaysia (2001–2003) and currently the Regional Chairman of the Coordinating Committee of APEC Engineers Register (2002–2003 and 2003–2005). Dr. Gue has recently been appointed as the Head Commissioner of ASEAN Engineers Register Commission. He is also a member of several professional associations and institutions, and was appointed as advisor/technical committee member to several Government Authorities. Ir. Dr. Gue is a registered Professional Engineer with more than 23 years of experience and more than 20 years in Geotechnical Engineering. His main specialization is in Geotechnical designs, failure investigations, remedial proposals, expert witness and mediator. He has published over 60 technical papers.

The synopsis of this talk as provided by The Institution of Engineers, Malaysia is as follows.

The construction of residential buildings on hill-site in Malaysia has increased tremendously for the last 15 years due to depleting flat land and other influencing factors like beautiful scenery, fresh air and exclusiveness. Hill-site development is often related to landslides and media coverage on landslides especially in the recent monsoon has raised concern on the safety of buildings on hill-site. Landslides have become a popular topic of discussion among engineers and public.

The truth is hill-site development is safe with proper planning, analysis, design, construction and maintenance. This talk presents brief guidelines on the above engineering aspects of hill-site development for engineers (target for non-geotechnical engineers) and answers to some of the common misconceptions. Case histories and lessons learned from projects on hill-site developments will be discussed together with some simple checklists to prevent slope failures.

Engineering input for hill-site developments:
─ Planning
─ Analysis & Design
─ Construction
─ Maintenance

The case history of the Highland Towers failure will not be covered as it is an old case. The Highland Towers collapse claimed 48 lives. The slope failure which occurred in Bukit Antarabangsa in 1999 did not claim any lives. Can slope failure be prevented with Geological Study? No. Geological Study only tells the history of the soil and rock. It does not design or analyse the stability of slopes. Failure is due to lack of engineering design. IEM states that hill-site developments is limited for residential properties only.

Hill-site developments have to be evaluated by an accredited checker for
─ Classification of risk
─ Any danger

Can hill-site developments be safe? Yes. A Desk Study can be done with Geological Maps & Memoirs, Aerial Photographs & Topographic Map. Site Investigation (SI) should be performed using boreholes to check the soil below ground or by seismic survey. Dr. Gue said that site investigation should not be done in a grid for the hill-site.

Dr. Gue said that the maximum hill-site gradient should be 10%. Dr. Gue also said that IEM has stated that no developments should be constructed on slopes which are steeper than 35 degrees.

For a 10% slope:

Assuming 1 m run:

For 35 degree slope:

On hill-site construction, retaining walls should be minimised. Cut and fill should also be minimised. Earth filling should not be done on slopes as this is an unstable foundation material. Soil can be strengthened by using soil nails.

Fig. 1: Buildings developed on hill-sites should be supported by stilts.

For developments on slopes, the building should be supported by columns or stilts. At the base of the columns would be the pilecaps and piles. The piles may be required to be longer to resist lateral movement which may occur if the building tends to slip down the slope.

The “chicken and egg” theory may occur as follows. A road section which was constructed on a slope has collapsed and the water pipes underneath have broken because of the collapse. Therefore an argument has broken out between the road developer and the water board personnel. The water board personnel say that their pipes have been broken because the road developer did not construct the road properly which caused the landslide. The road developer says that the fault was with the leaking pipes under the road which caused the landslide which destroyed the road.

The water table under the slope can also cause slope failure. Slip circle analysis, such as Bishop’s Method (1955), can be used to predict where failure is likely to occur (Smith, 1990, p. 175). Slip circle analysis will provide a factor of safety (FOS) for a given circle. The centre of the most critical circle, with the minimum factor of safety, can only be found by trial and error. Then (Smith, 1990, p. 159):

where c_u is the undrained cohesion of the soil in kN/m², r is the slip circle radius in m, θ is the angle in radians, W is the weight of soil acting at the centroid of the slip circle in kN and e is the horizontal distance from W to the centre of the slip circle in m. This is shown in Fig. 2. Alternatively, wedge failure analysis can be performed (Smith, 1990, p. 187). We were shown a table with the various acceptable values for factor of safety which is being used in Hong Kong.

Fig. 2: Slip circle analysis can be used to determine the factor of safety for a slope against failure.

Dr. Gue also talked about the c’ and Φ soil parameters. Dr. Gue said that the cohesion c’ should be taken as zero (c’=0) unless the soil has been properly tested. Dr. Gue also said that c’ should be taken as less than 10 kPa. Soil suction should not be considered.

Causes of slope failure include:

─ High intensity rainfall
─ Lack of slope maintenance
─ Incorrect, improper design, analysis and construction

During question time, Dr. Gue was asked about the length of soil nails which should be used. Dr. Gue said he has used soil nails of 18 m in length but 12 m can also be used. Dr. Gue said that soil nails should be checked every 6 months and retightened if necessary. He further added that this wasn’t done in Malaysia except at Genting Highlands. Dr. Gue was asked about how it would be possible to make a slope safe if there was a water table below ground level. Dr. Gue said that horizontal drains can be used to drain out the water table.

Latest Aerosol Technology for Fire Suppression

2006-05-12T21:27:00.006+08:00

This talk entitled “Latest Aerosol Technology for Fire Suppression” was presented by Dr. Julia Berezovsky on Friday, 12 March 2004 at the IEM Conference Hall in Petaling Jaya, Selangor. The talk began at 5.30 p.m. and ended at about 7.00 p.m.

The biodata of the speaker as provided by IEM is as follows.

Dr. Berezovsky is primarily responsible for testing, development, research, certification and appraisal of Pyrogen as a new Halon replacement aerosol chemical fire extinguishing system. She ensures the efficient running of Research & Development Department working in close liaison with end-users, manufacturers and certification bodies. She is also in charge of the elaboration of:
· Product Standards
· Technical Specifications
· Design, Installation, Operation and Maintenance Manuals
· Safety Material Data Sheets
· Advertising Brochures (Technical Details)
· Evaluation & Approval of New Applications and Systems for Pyrogen

She actively negotiates with international suppliers, national and international distributors and collaborates with regulatory authorities. She is also required to train personnel and conduct presentations/lectures held for Fire Protection Authorities and companies whereby her five years as a university lecturer/tutor in physical and inorganic chemistry and chemical technology proves to be a beneficial experience. She was attached to The University of NSW from 1993 to 1994 and Moscow Teachers Training University from 1987 to 1992. Dr. Berezovsky received her Doctorate in Chemistry from University of Moscow in 1987.

Prior to joining Pyrogen, she has accumulated 7 years of experience as a Research Scientist dealing with physical and inorganic chemistry of solid oxygen conductors and new ceramic materials, solid oxide fuel cells and oxygen sensors, electrochemical corrosion of metals, ecologically clean cooling agents, aerosols and ecology problems.

Dr. Berezovsky also represents Australia (nominated by Standards Australia/NZ) on the ISO sub-committee that is working on the ISO Standard for the fine aerosol technology. She also participates at the CEN European Standard committee as a guest member and a technical expert on the aerosol technology.

The synopsis of this talk as provided by IEM is as follows.

This talk introduces condensed aerosol technology for fire suppression, its unique features, technical characteristics, performance, design standards, applications, etc. A brief introduction of this technology can be summarized as follows:

Condensed aerosol fire suppression technology had been developed in Russia after the WWII as a by-product of the “flameless” solid propellants. It is recognised as one of the most effective and simple solutions in the task of protecting the industrial enclosed areas such as electrical substations, transformers, switchboards, generator rooms, stores, machinery and equipment, engine compartments of vessels and automotive vehicles and many other risks from fires and associated damages.

The extinguishing principle of the condensed aerosol technology is unique—a special solid chemical when activated produces an aerosol which is an extinguishing medium in itself. The extinguishing medium however is not stored in a cylinder, it is produced in-situ only when required. The aerosol is a mixture of gases and micron-sized solids possessing gas-like distribution properties and long holding times.

Unlike conventional fire suppression systems, condensed aerosol systems can be characterized as requiring no piping, zero storage pressure, solid-state technology, environmentally friendly, non-conductive and non-corrosive and has significant space and weight advantages in comparison with gaseous systems.

Pyrogen was developed using solid propellant technology and is the world’s first commercially available Condensed Aerosol Fire Suppression System. Pyrogen is an inert non-toxic solid that remains stable until electrically or thermally activated whereupon it produces gas-like extinguishing aerosol. Pyrogen aerosol attacks the fire chemically and physically giving virtually instant extinguishment and preventing re-ignition.

The participants at this talk were given a file containing printed material with information about Pyrogen. A computer CDROM was also included with some videos in it. Some of the printed material have been photocopied and are included in the Appendix of this report. The talk started around 5.48 p.m. Mr. Richard Lee, Regional Manager Asia of Pyrogen Corporation Sdn. Bhd. began by giving us some information about Pyrogen. The contact details of Pyrogen Corporation Sdn. Bhd. are as follows:

Pyrogen Corporation Sdn. Bhd.
2A Jalan SS 13/3D, Subang Jaya Industrial Estate, 47500 Subang Jaya, Selangor
Tel: 03-56212211 Fax: 03-56215566 Website: http://www.pyrogen.com/
E-mail: pyrogen@tm.net.my, heechoi@pyrogen.com

Mr. Lee told us that Pyrogen was available in Australia since 1993. It is an aerosol technology to be used as a replacement for Halon which has been decommissioned. Halon has been banned because it destroys the ozone layer. One kilogram of Halon destroys 50 tonnes of ozone. With aerosol technology, there is no need for piping which was required with Halon. In Malaysia Pyrogen is used by companies such as Mimos, Telekom Malaysia, Celcom and Petronas. Overseas, British Energy and Anglo Gold are some of the companies which use Pyrogen.

We were then introduced to Dr. Berezovsky who took over from Mr. Lee. We were informed that Dr. Berezovsky is presently a permanent resident of Australia. Dr. Berezovsky was asked what “CEN” means. She replied that it means European Standards. We were informed that Pyrogen is 3 times more effective than Halon. It is listed by the US EPA and recognised by Standards Australia. Aerosol technology was discovered after World War II, however it took a long time to be approved. Dr. Berezovsky told us that there are 4 main elements to a fire being fuel, heat, oxygen (O₂) and chain carriers (O, H & OH). Chemical extinguishment of the fire requires the removal of the chain carriers. For Pyrogen, 100 g/m³ is required while for Halon 330 g/m³ is required. The units g/m³ refer to grams of chemical required to protect the volume of enclosure in m³. The amount of Pyrogen required is designed in g/m³. Therefore using Pyrogen will save on space when compared to using Halon. Pyrogen does not deplete oxygen. This is unusual because usually oxygen needs to be removed in order to extinguish the flame.

Pyrogen has been published in the standard AS/NZS 4487: “Pyrogen fire extinguishing systems”. Pyrogen is available in many sizes including hand deployed units whereby a ring is pulled and the canister thrown into the fire like a hand grenade. There is a 10-second delay before the fire extinguishing chemical is released. For the non-hand deployed units, Pyrogen is activated in three ways:

1. By sending an electrical signal from a control panel to the Pyrogen canister
2. When the fire conducting cord is heated to ≥ 175 degrees C
3. When the fire burns the fire conducting cord

Fig. 1: Non-hand deployed Pyrogen can be activated in 3 ways, by sending an electrical signal from a control panel, when the fire conducting cord is heated to ≥ 175 degrees C or when the fire burns the fire conducting cord itself.

Fig. 2: Hand deployed units are like grenades. The pin is pulled and the Pyrogen canister thrown into the fire.

Dr. Berezovsky told us that every CNC machine now has Pyrogen built-in. CNC machines are used by industries such as the plastic manufacturing industry in plastic injection moulding. When activated, the aerosol discharges out from one end of the canister. The sealing at the end of the canister which looks like foil tears off from the force of the escaping aerosol. The aerosol resembles a smoky white coloured gas which extinguishes the fire. There is no water which makes Pyrogen suitable for use with electrical and other types of fires.

Fig. 3: Construction of the Pyrogen canister. The fire extinguishing aerosol is released from the right side. The pressure from the aerosol blows off the blow off cover which is a thin paper like seal covering the holes on the directional plate.

Fig. 4: Dr. Julia Berezovsky presenting her seminar on Pyrogen at The Institution of Engineers, Malaysia.

Rock Tunneling

2006-05-06T22:12:00.002+08:00

The talk entitled “General Overview of Various Completed Tunneling Projects in Malaysia with Particular Emphasis on Rock Tunneling” was presented by Ir. Gary Ng Fook Kwai on Monday, 16 February 2004 at the IEM Conference Hall, 2nd floor, The Institution of Engineers, Malaysia in Petaling Jaya, Selangor. The talk began at 5.30 p.m. and ended just after 7.00 p.m.

Ir. Gary Ng, PE, MIEM, BSc., MSc. (Civil), graduated from Texas A&M University, USA with a Masters degree in Civil Engineering about 20 years ago. His specific area of expertise is in the construction of tunnels, highways and railways. He has been involved in project management, construction supervision and contracts administration for a number of mega infrastructure projects both in Malaysia as well as in the USA. He has extensive tunneling experience and the tunnel projects for which he was involved both as a contractor and as a consultant were Sungai Piah Hydroelectric Tunnel, Jelapang Menora Tunnel, Dallas, Texas, USA Storm Sewer Tunnel and the Kuala Lumpur LRT Tunnels. He is currently the Head of Construction for the Government PMC at the Ipoh Rawang Electrified Double Track Project.

The synopsis of this talk as provided by The Institution of Engineers, Malaysia is as follows.

Since the completion of the Kuala Lumpur LRT tunnels and the launch of the SMART tunnel, considerable awareness and interest has recently been generated amongst engineers on the design and construction of the underground infrastructure facilities.

In tunnel excavation works, different geological subsoil profiles will generally dictate different construction techniques and selection of excavation machineries to be utilised in the tunneling works. Among the completed tunneling projects in Malaysia are Cameron Highland Hydro Electric Power Tunnel, Sungai Piah Hydro Electric Tunnel, North-South Highway Jelapang Menora Tunnel, Kuala Lumpur PUTRA LRT Tunnels and Karak Highway Tunnel. Various construction techniques such as Tunnel Boring Machine (for soft ground/mixed face/soft rock) and NATM (for granite/limestone rock) tunneling methods were used to construct the above said tunnels.

In this talk, the speaker will share his vast tunneling experience and give you an insight into the construction details of some of the above mentioned projects, which he had personally been involved in. He will particularly emphasize in his presentation on rock tunneling, design of blasting pattern, rock classification/mapping for temporary rock bolt/dowel/shotcrete support, tunnel ventilation and various problems encountered during the tunneling works. These hands on experiences will be invaluable to those who are involved or interested in tunneling works.

Ir. Ng informed us that since his graduation he has worked on four projects being the Ipoh-Kuala Kangsar Highway, Sungai Piah Hydroelectric project, North-South Highway and Kuala Lumpur LRT tunnels. Tunneling equipment and site investigation is important in tunneling projects. Subsurface conditions can be checked using seismic surveys or boreholes.

After every blast, the geologist collects the blasted rock samples for analysis and mapping. The geologist then decides what type of supports are needed to hold up the tunnel roof and walls. In selecting the tunnel steel ribs to hold up the rock in case of collapse, the ribs should be able to withstand the entire weight of the material above the tunnel ceiling to the ground level above. The side walls of the tunnel are also subjected to the hydrostatic pressure which increases with depth below ground level. This pressure is equal to:

where P is the sideways pressure in kN/m², γ is the average material density (kN/m³) from ground level to the depth under consideration and H is the distance from ground level to the depth under consideration (m). Therefore the design pressure at the tunnel sidewalls will be slightly more than at the ceiling due to its location being deeper than the ceiling. By using steel ribs at a closer spacing the design pressure to be resisted by each rib is decreased. After blasting, the steel ribs should be installed as soon as possible.

Fig. 1: The tunnel steel ribs have to be designed to withstand the entire weight of material above it and also the sideways hydrostatic pressure.

Ir. Ng informed us that tunnel ventilation is very important. After every blast, there are noxious gases being generated. These noxious gases are carbon monoxide (CO) and nitrogen dioxide (NO₂). Ventilation can be achieved by using electric fans. Only after the noxious gases have dissipated should the personnel be allowed into the tunnel. We were informed that Emulite or ANFO are common types of explosives which are used.

Fig. 2: The steel ribs are rock bolted to the tunnel interior.

The steel ribs are bolted to the rock in the tunnel by using rock bolts. This is performed by drilling a hole and then squeezing resin into the hole. The steel bolt is then quickly placed into the resin filled hole and the resin is allowed to dry and set. It is now possible to tighten the rock bolt with a nut and plate on the inside of the rib. The rock bolt therefore acts like a prestressed tendon in holding the steel rib in position to the tunnel rock wall. To stabilise the tunnel rock wall, steel fibre reinforced shotcrete is then sprayed onto the cavern walls.

The explosives are usually placed in a horseshoe shape for blasting the face of the tunnel. There could be up to 42 numbers of explosives on the tunnel face to be blasted. Holes are drilled into the face and the explosives are placed inside the holes. The position of the holes can be marked in paint beforehand by using a pre-made template which could be a steel plate with holes cut into it. The rock drill can be pneumatically powered and hand-held or be a large drilling machine on wheels or crawlers.

Fig. 3: Holes are drilled in a horseshoe shape.

The explosives are not fired off simultaneously. The blasting is timed with the central explosives going off first, moving radially outwards to the perimeter. The explosives at the centre of the face usually have a millisecond delay from each other while the perimeter explosives may have half-second delays. We were informed that the hole at the centre of the blast face is hollow and has no explosive inserted. We were not informed as to the reason for this. Each explosive on the face is wired back to the detonator which is located at a safe distance. There should be sufficient explosives to ensure that the rock fragments are not too big and therefore heavy. This will cause a difficulty in mucking out the material. Machines are used to muck out the material from the tunnel. The spacing of the explosives is therefore important. If the spacing is too close, a phenomenon known as desensitization can occur. This means that some of the explosives may not go off because they are too close together.

Fig. 4: Desensitization may occur if the explosives are placed too close together. This means that some of the explosives may not go off.

There is a Blasting Handbook which outlines the criteria on spacing and other topics related to blasting with explosives. It can be followed for effective and efficient blasting. We were informed that it is important to know the type of rock which is being detonated. Trial blasting can be used and the type of explosives, delay and spacing adjusted with each blast for best efficiency.

Fig. 5 shows the layout of the explosives on the tunnel rock face. They are all individually wired to the detonator and are suitably delayed. Fig. 6 shows how a cutting can be blasted. The purpose is to create a free face as shown. When the first row is detonated, the free face should move left to the location around the explosion. The second row of explosives can then be detonated to bring the free face further to the left. Hills can be blasted in this way to create a cutting for a roadway, railway, dam or township.

Fig. 5: Wiring the explosives to the detonator.

Fig. 6: Blasting to create a cutting.

Ir. Ng then talked to us about the Kuala Lumpur PUTRA LRT project, which he was involved in. The three contractors were Hyundai, Hazama-gumi and S&C. Tunnel boring machines (TBMs) were used to create the tunnels. At some locations the tunnels are below the Klang river and at some parts as deep as 20 m below it. Some of the problems faced was the extremely hard rock with a strength of 270 MPa. An underground aquifer also posed some problems and pumping of the water was required. We were shown some colour slides of the projects which Ir. Ng had been involved in including some pictures which were taken in Texas, USA. There were no questions from the audience and the session ended just after 7.00 p.m.

Scour Prediction At Bridges

2006-04-29T20:42:00.004+08:00

The talk was entitled “Scour Prediction at Bridges” and was presented by Ir. Chen Wai Peng on Wednesday, 12 January 2005 at the Institution of Engineers, Malaysia (IEM) Conference Hall, 2nd Floor, Bangunan Ingenieur, Lot 60–62 Jalan 52/4, 46720 Petaling Jaya, Selangor. As usual, food and drinks were available for consumption before the talk. The talk began at 5.30 p.m. and ended at about 6.20 p.m.

The synopsis of the talk as provided by Ir. Dr. Quek Keng Hong, Chairman, Water Resources Technical Division, IEM is as follows.

In the several studies carried out on bridge failure, at least half of the failures were due to floods and other action of water. Scour is a potential contributing factor for the failure and is believed to be the most common cause of failure or damage to bridges during floods, although the immediate cause may be due to other factors, such as water pressure on a bridge deck, or debris impact force. Because of this, there has been much research work on scour estimation. Despite of so much studies, the results of the various investigations often show differing trends and sometimes contradictory.

Most of the equations for scour were derived from laboratory studies with unknown range of validity or verified using very limited field data. Measurement of scour holes during flood is also difficult and often the holes are filled in after the flood or with other material.

The talk will give an introduction to various types of scour and an overview of the various equations used in scour prediction and the various method of countermeasure together with their limitations will also be discussed. Finally, an example will be discussed with the application of those equations with field measurements.

The Bio-Data of the Speaker as provided by Ir. Dr. Quek is as follows.

Ir. Chen Wai Peng qualified with B.Sc. (Eng.) from Imperial College, University of London. He commenced his engineering profession with Jabatan Perparitan dan Saliran and has worked with several consulting firms and assumed various portfolios including Design Engineer, Head of Department, Project Manager, Team Leader and Project Director, etc. In the past 24 years of his career, he managed to accumulate valuable experience through his involvement in a number of large scale projects such as Master Planning of Kuala Lumpur International Airport (KLIA), Putra LRT, West Port Development, Widening Penang Second Crossing, Feasibility Study of Penang Third Crossing and many bridges, ports and township development projects in Malaysia. Ir. Chen’s main interest are on bridge and geotechnical design. He is presently the General Manager of the Special Projects Division of HSS Engineering Sdn. Bhd.

Ir. Dr. Wong Wai Sum introduced us to Ir. Chen Wai Peng. Ir. Chen informed us that the notes were prepared before the Asia Tsunami which occurred on 26 December 2004. The Asia Tsunami killed many people in Indonesia, Thailand, Sri Lanka, Malaysia and several other countries. Ir. Chen’s main interests are on bridge and geotechnical design. The presentation was presented with a laptop computer and LCD projector.

Ir. Chen talked about Scour Failure. There are equations for:
- General Degradation
- Contraction Scour
- Local Scour

Fig. 1: Scour at bridge pier.

A scour hole may occur at a bridge pier. This erosion is caused by the flow of water at the vicinity of a bridge pier. At the upstream side of the pier water hitting the pier may flow downwards causing the scour hole. At the downstream side of the pier water may flow backwards and down causing the scour hole. Scour holes can cause a bridge to collapse due to weakening of the foundations. Although the pier is usually supported by piles, scour holes can reduce the pile capacity. Bridge movement may occur. The abutments may fail due to scour.

Fig. 2: Scour can reduce the pile capacity.

Scour Prediction is used to predict the properties of the scour hole. Counter measures can then be taken to prevent scour holes from occurring. There is long term and short term scour.

Clear Water Scour occurs at low flowrates.
Live Bed Scour occurs at higher flowrates.

When a river discharges due to a storm, first there is clear water scour, followed by live bed scour which then returns to clear water scour again when the storm flow has subsided.

Ir. Chen showed us several General Degradation equations. I was only able to copy down a few of the equations before the projection which was being shown was changed. The following are some of the equations which I was able to copy down.

Lacey (1930):

Blench (1969):

There was also the Maza Alvarez and Echavarria Alfaro (1973) equation which I was not able to copy down. Ir. Chen showed us many other equations and charts during his presentation. By using equations it is possible to predict the depth of scour. The critical velocity Vc is used to determine whether clear water or live bed scour occurs. Above the critical velocity live bed scour occurs while below the critical velocity clear water scour occurs.

In order to minimize scour Ir. Chen said:
1) Rounded piers can be used.
2) Align the piers to the direction of the flood flow.
3) Use streamlined piers.
4) Use spill-through abutments rather than vertical walls.
5) Gabion mattresses, rip-raps and sheet piles can be used.

The presentation ended at 6.14 p.m. This was followed by a question and answer session. Ir. Chen was asked about whether safety factors were included with the equations. The CSU equations were mentioned. Ir. Chen was told that the results from the equations were very scattered. Another member of the audience asked Ir. Chen how it is possible to design the protection against scouring. Ir. Chen said to use rip-raps, equations, the Shore Protection Manual and HEC18. The talk then ended at 6.20 p.m.

Seismic Refraction Technique

2006-04-12T22:09:00.003+08:00

The talk entitled “Seismic Refraction Technique in Civil Engineering Applications” was presented by Mr. Ng Chak Ngoon of Subsurface Engineering Sdn. Bhd. Mr. Ng. graduated from The University of Malaya with Honours in 1971. He has worked as an engineering geologist for over 20 years as a consultant and contractor in various projects including the North-South Highway, Malaysia-Singapore Second Crossing and the Kuala Lumpur International Airport. He is currently the Chairman of the Engineering Geology Group in the Institute of Geology Malaysia (IGM) and Vice-President of MSIA. He has given technical talks and presented papers in the application of geology in engineering and site investigation.

The talk was held on Thursday, 29 January 2004 at 5.30 p.m. at the Conference Hall of The Institution of Engineers, Malaysia in Petaling Jaya, Selangor. Unfortunately, the air-conditioning system was not working and the speaker and those in attendance were required to attend to this talk under quite uncomfortable temperatures.

The abstract of this talk as provided by The Institution of Engineers, Malaysia is as follows.

Conventional seismic refraction data analysis assumes that seismic waves are critically refracted in the ground along layer boundaries provided each layer is having a higher seismic velocity than the one above. This is often true enough for the method to be effective especially in estimating the quantities of soil, hard material and rock in earthworks. When used with a limited number of checked boreholes, it enhances reliability and provides detailed information cheaper and faster than boreholes alone.

Recently developed traveltime tomography which does not assume that each layer has a higher seismic velocity than the one above, has further enhanced interpretations. Thus, it is possible to extend the applications of the technique to mapping highly irregular limestone bedrock profiles and the correlation of seismic velocity with soil strength parameters. It is limited only by extreme ground variation perpendicular to the seismic section.

The principles and methodology of seismic refraction survey are to be presented in terms of the applications and limitations of the method in engineering site investigation works. It will include the choice in the method of generating seismic signals, planning of seismic lines and selection of geophone intervals. Tomography techniques which are already well established in other fields such as MRI and ultrasound in medical field, are extending seismic refraction into applications previously impossible such as the mapping of limestone bedrock profiles and the subsurface material strengths.

Mr. Ng Chak Ngoon informed us that BS 5930 Site Investigation now draws more and more on Geophysical Methods. Geophysical methods are better than using the Mackintosh probe for example. The advantages in using geophysical methods are:
1. Comprehensive information
2. Low cost
3. Fast

Geophysical methods are under-utilised because of:
1. Unfamiliarity
2. Bad experience

In checking the hardness of a soil or rock layer, blow-counting can be used. The higher the blow-count, the harder the material. In general, harder material is encountered with increasing depth below the ground surface. This can be caused by compression forces of the overburden material or that a hard layer such as bedrock exists naturally. Therefore, the seismic velocity also increases with increasing depth below the ground surface as the hard material or compressed soil strata is able to transmit wave energy more efficiently than loosely packed material such as unconsolidated soil.

Fig. 1: Wave fronts refracting at ground layer boundaries due to difference in hardness.

Mr. Ng referred to the Law of Refraction which can be used to explain how seismic wavefronts refract at boundaries of different hardness under the ground surface. The law of refraction is as follows (Giancoli, 1991, p. 295):

(1)

where v₁ and v₂ refer to the speed of the waves in medium 1 and 2 respectively.

Fig. 2: Refraction occurs when waves pass through a boundary of different mediums which affect the speed of the waves.

The angle θ₁ is the angle of incidence while θ₂ is the angle of refraction. They are measured from the perpendicular to the boundary. The wave fronts are at right angles to the rays as shown in Fig. 2. From equation 1, the angle which the ray makes with the perpendicular is larger for the faster medium and smaller for the slower medium. Although air and water is shown in Fig. 2, the same principle applies for different soil layers under the ground. The angle of reflection is equal to the angle of incidence. For clarity, the reflected wave fronts associated with the reflected ray have not been shown in Fig. 2. The law of refraction is also known as Snell’s law. The relationship between θ₁ and θ₂ was arrived experimentally about 1621 by Willebrord Snell (1591–1626) whereby in it’s original form it was written as (Giancoli, 1991, p. 601):

(2)

n₁ sin θ₁ = n₂ sin θ₂

where n₁ and n₂ are the respective indices of refraction. The value of n is greater if the speed is less. In his experiments, Snell noticed that the ray is bent toward the normal when the speed was less.

The purpose of performing a seismic survey is to obtain information about the conditions below ground level. The seismic survey is used to obtain an image of the boundary layers which may exist below the ground level. This is helpful in foundation design, for example, if a layer of bedrock exists only a few metres below the ground, the piling can be designed appropriately to take advantage of this natural condition. Likewise, if no hard layer exists, the pilecaps may need to be enlarged to accommodate more piles. For road construction, knowledge of conditions below ground level is useful in determining how much earth can be cut and to determine the most efficient route.

A device known as a geophone is used for seismic survey. It is like a microphone. Mr. Ng informed us that usually 24 numbers of geophones are used. They are spaced at 5 m from each other although a closer spacing can be used for better resolution. The geophones are connected to an electronic seismic recorder or to a computer for analysis. The geophones are placed in a line at the 5 m intervals. In order to create the seismic signals, explosives can be used. We were informed that explosives are the best for the creation of seismic signals. However, a police permit is required. If no explosives are available or it is not possible to obtain a permit, a drophammer can be used similar to the standard penetration test (SPT). Ground penetration radar is not a good device for obtaining subsurface information as it is not able to penetrate the water table.

We were informed of the 4 types of seismic waves being:
– p waves which move parallel to the ground surface in compression or tension
– s waves which act as shear waves moving up and down perpendicular to the ground surface
– love waves which move sideways
– Rayleigh waves which move in circles under the ground surface

Fig. 3: Rayleigh seismic wave.

With geophysical methods, we are interested only with the p waves. The computer which the geophones are connected to can then analyse the data provided. The seismic refraction software loaded into the computer is able to convert the data into velocity contours which can show the various boundary layers below the ground surface. Fig. 4 shows an example of how a bedrock layer below the ground level is outlined by the velocity contours.

Mr. Ng informed us of several projects which he has worked on using seismic survey, one of which was to check the depth at which limestone existed below ground level for the Rawang–Ipoh Electrified Railway Project at Batang Kali. Seismic survey was also used at Batu Caves to determine where the layer of granite exists. By knowing where the rock level is, it is possible to know how much soil must be removed for excavation. We were informed that the SPT N-value and seismic velocity have a very good correlation with each other.

During question time, Mr. Ng was asked whether seismic tomography can be used to determine the location of the water table. Mr. Ng said that 2D resistivity test can be used to check the location of the water table. In this procedure, a current is passed from several electrodes to the receiving electrodes and the conductivity of the soil is measured. The data which is received from the electrodes are analysed by computer. High soil conductivity suggests that the soil could be saturated or the presence of a water table.

Fig. 4: Seismic velocity contours provided by the seismic refraction software can show the different layers present below ground level.

After answering the questions, the talk ended at about 7.00 p.m.

REFERENCE
Giancoli, Douglas C., 1991, “Physics Principles with Applications”, 3rd Edition, Prentice-Hall, USA.

The SMART Tunnel

2006-04-02T01:21:00.006+08:00

The talk entitled “Rainfall-Runoff Simulation for Upper Klang Valley” was presented by Ir. Dr. Wong Wai Sum on Wednesday, 18 February 2004 at the IEM Conference Hall, 2nd floor, The Institution of Engineers, Malaysia in Petaling Jaya, Selangor. The talk began at 5.30 p.m. and ended at 7.00 p.m.

Ir. Dr. Wong obtained his B.Eng., M.Eng.Sc. and Ph.D. degrees from University of Malaya. He is currently the Hydrology and River Engineering Section Manager of Dr. Nik & Associates Sdn. Bhd. and is actively involved in drainage and flood mitigation master plan studies, integrated river basin management studies, detailed design and computer modelling works. The projects he has participated or headed are the Multimedia Super Corridor Macro Drainage Master Plan, Klang River Improvement Works, Sungai Buloh Flood Mitigation Master Plan, Sungai Rompin and Sungai Sedili Besar Salinity Intrusion Study, Sungai Paka Sediment and Sand Mining Study, Batang Sadong Feasibility Study, etc. and he was the project manager for the study of the Klang River Basin Environmental Improvement and Flood Mitigation Project. He is a current team member of the Specialist Consulting Engineers for the Government in the SMART project.

The synopsis of this talk as provided by The Institution of Engineers, Malaysia is as follows.

The project work involved a detailed review of previous studies and projects, a review of hydrological data and hydrological analysis, hydraulic modelling and development and evaluation of flood mitigation options. The hydrological and hydraulic analyses and modelling simulations carried out to date have been based on a thorough review and analysis of hydrological data that has been linked to very refined land use cover data and application of innovative and soundly based techniques.

The quality of the available hydrological data has been thoroughly reviewed and data revisions made where necessary. Rainfall data is generally good while the streamflow data and derived rating curves are considered to be good to fair from only two stations—the Batu River at Sentul and the Klang River at Sulaiman Bridge.

The hydrological model applied for the studies is the MIKE 11 RR module based on the NAM model that simulates runoff for the pervious portions and the Urban model that simulates runoff from the impervious portion. This approach has allowed the simulation of the effect of alternative future urban development scenarios. Calibration of the RR module has been based on continuous simulation and recorded runoff, simulation of nine high flow events occurring over the last three years and combined calibration with the MIKE 11 hydrodynamic (HD) model. Attention has been paid to the importance of correctly simulating runoff volumes as well as peak discharges.

The combined models have been used to evaluate the present conditions of the rivers and causes of flooding in the city area and to evaluate proposed future flood mitigation implementation and a number of other options including SMART tunnel and flood storage system at Batu and Jinjang ponds. The models are also now being used actively as the Flood Forecasting model that was installed at DID Wilayah.

We were informed that Dr. Wong is now with Dr. Meng & Associates. Prior to this, he was with Minconsult Sdn. Bhd. We were shown some pictures of the flooding in Kuala Lumpur which occurred in 1971. Therefore, the Department of Irrigation and Drainage (DID) began implementing the Kuala Lumpur Flood Mitigation Project because of flooding in the Kuala Lumpur City Centre. Dr. Wong informed us that flood mitigation is carried out from downstream towards the upstream of a river. The Klang River has undergone widening and deepening to facilitate for storm flow. It has also been lined. However, this has not solved Kuala Lumpur’s flooding problems. Due to land shortage and high density development on both sides of the Klang River, it is not possible to further widen it. Therefore other steps have to be taken to prevent flooding when it rains heavily.

Fig. 1: The Klang River is discharging a larger flowrate today than it was many years ago.

Fig. 1 shows how the Klang River is discharging a larger flowrate today than it was many years ago. This is caused by urbanization and development on both sides of the river. The construction of pavements and footpaths increases impervious runoff to the river. The construction of buildings in the city and at other areas means that more wastewater is discharged to the river.

Sprinkler Infiltration Experiments have been carried out at Batu Pond, FRIM and Taman Titiwangsa. The results for Batu Pond and FRIM are as follows.

Batu Pond Total 1 hour = 25 mm
Basic rate = 12 mm/h
FRIM Total 1 hour > 100 mm
Basic rate > 50 mm/h
Therefore at different locations infiltration and surface runoff may vary depending on the soil and subsurface conditions.

Several rain gauges have been installed around the Klang Valley. This allows for the plotting of the Cumulative Mass Curve for each precipitation event for each rain gauge.

Fig. 2: Cumulative Mass Curves obtained from various rain gauges.

The rainfall-runoff model used is the MIKE 11 NAM module. The urban model uses the kinematic wave equation. Thiessen polygons are used for each rain gauge to determine the influence area for each station. The Thiessen method assumes that at any point in the watershed the rainfall is the same as that at the nearest gauge so the depth recorded at a given gauge is applied out to a distance halfway to the next station in any direction (Chow et. al., 1988, p. 78).

There are three land situations being Present, 2020 Pelawi II and 2020 with Planning and Runoff Control. The carrying capacity of the Klang River at Tun Perak Bridge is between 180–200 m³/s (cumecs). With regard to preventing floods in KL city, one solution is to divert the flow away from the Gombak River.

Fig. 3: Constructing a tunnel to divert the flow from the Gombak River further downstream.

This involves constructing a tunnel underground to allow flow from the Gombak River to be diverted further downstream. This is not a good solution because there could be flooding downstream or backflow in the diversion tunnel which may not prevent flooding at the tunnel intake. A better solution is to divert flow from the Gombak River to two ponds being the Puah Pond and the Benteng Pond. These ponds serve as temporary stormwater storage basins. When the storm has passed, the ponds can be drained by pumps. They are then ready to receive water when the next flood arrives. The problem with this method is that the ponds may have insufficient capacity and may overflow during a large storm. Alternatively, there could also be a storm at the location of the ponds which reduces their storage capacities.

The government has approved an alternative method which is called the SMART tunnel. SMART stands for Stormwater Management and Road Tunnel. The SMART tunnel is a tunnel with three sections. The upper two sections are roadways to cater for traffic. Each section allows traffic to travel in one direction. The third section at the bottom is a stormwater tunnel. Therefore the traffic is moving directly on top of a stormwater channel. The entire stormwater channel is approximately 11 km long. The SMART tunnel which consists of the roadway and stormwater channel is 4 km of the total length. During an impending flood, the upper two roadways will be closed to traffic and evacuated. The entire three sections of the SMART tunnel will now be ready to carry flood waters. The flood waters will flow through the SMART tunnel from KL city to a receiving pond about 11 kilometres away. When the flood has passed, the tunnel can be reopened for traffic. Therefore the tunnel has two purposes, to allow motorists to travel faster to their destination by using the additional roadways and to prevent flooding in KL city. Toll will be collected from motorists who use the SMART tunnel. The SCADA system will be used to control the floodgates and to monitor the SMART tunnel. Of great importance are two things—fire safety and water tightness. Heavy vehicles will be prohibited from using the SMART tunnel. There will be emergency exits at every 250 m intervals. There will be two ventilation ducts housing air-moving equipment. The ventilation ducts will be at each end of the tunnel. At one duct, a fan will blow fresh air into the tunnel. At the opposite end, an exhaust fan will suction polluted air and smog out of the tunnel.

Fig. 4: Cross-section of the SMART tunnel which the Malaysian government has approved for construction.

We were then shown two video presentations. The first video was on using diversion tunnels and channels to convey flood waters to storage ponds which can then be drained by pumps after the storm has passed. The second video was on the SMART tunnel. During question time, Dr. Wong was asked about rain forecasting. Dr. Wong said that low pressure indicates a good likelihood of rain. He added that it is very difficult to accurately forecast rain and that the weather bureau of Malaysia has yet been unable to provide accurate weather forecasting.

REFERENCE
Chow, Ven Te, Maidment, David R., Mays, Larry W., 1988, “Applied Hydrology”, McGraw-Hill, Singapore.

Backwashing and the Automatic Submersible Pump

2006-03-31T00:38:00.005+08:00

Backwashing can be added to a water filter by adding pipes and ball valves around the filter. Backwashing is usually added to a whole house filter and not a drinking filter. Backwashing can prolong the life of the filter cartridge. Opening ball valves A & C while closing ball valves B & D will activate the backwash.

Adding the backwash function to a water filter.

A submersible pump is located underneath the water surface. The switch is tied to the pump by a cable. The switch is a round plastic thing which floats on the water surface with a ball bearing inside it. When the water level rises, the ball bearing inside will roll towards the contact point. As the ball bearing is metal, electricity will flow switching the pump on. When the water level drops, the ball bearing rolls away from the contact switching the pump off.

Submersible pump with automatic water level detect.

More on the World Trade Centre, USA

2006-03-11T23:01:00.003+08:00

Top view of the WTC tower.

Elevation view of the WTC flooring system which was both steel and concrete.

The World Trade Centre (WTC) in New York was unusual because it was constructed using both cast in-situ reinforced concrete and steel. Most high-rise buildings in Malaysia are constructed using cast in-situ reinforced concrete.

For the WTC, the core was where the elevators were. This was a structural wall with steel reinforcement in it. This is unlike a brick wall which has no steel reinforcement in it. The elevator wall is usually a structural wall and can support loading unlike a brick wall which generally cannot. A brick wall can be used to support drain covers for pedestrians to walk on. But a reinforced concrete floor slab, like the one you find in your house, has to be supported by columns or structural walls with reinforcing steel inside the concrete.

The floor of the WTC was constructed of steel trusses and steel decking was placed on top of the floor trusses. The steel decking would be corrugated like zinc roofing. Slab reinforcement is then placed on the decking and concrete poured onto the decking to form the slab. The corrugated steel decking is not removed. Therefore the slab is composite, being concrete on top but steel at the bottom. The false ceiling from the floor below will hide the corrugated steel decking.

A high-rise building such as Menara Maybank in Kuala Lumpur would be completely reinforced concrete. The floor slabs would also be reinforced concrete.

Information on the World Trade Centre courtesy of Dr. W. Gene Corley, Hon. ASCE, SE, PE, Senior Vice-President of Construction Technology Laboratories (CTL), USA.

Menara MPPJ and the World Trade Centre, USA

2006-02-24T19:24:00.001+08:00

Menara MPPJ in PJ State, Petaling Jaya looks like the World Trade Centre (WTC) in New York, USA although it is much shorter.

Closer view of Menara MPPJ which has an external facade like the WTC in Manhattan, USA.

The steel column trees of the WTC were closely spaced and in groups of three. The close spacing means that each column tree takes less load allowing for a greater building height.

The steel column trees may have looked something like this.

MPPJ (Majlis Perbandaran Petaling Jaya) is the Petaling Jaya Municipal Council. Menara MPPJ shown here is the headquarters of the PJ Municipal Council. It has been designed to look like the World Trade Centre in Manhattan, USA. The World Trade Centre towers in Manhattan were designed by Japanese architect Minoru Yamasaki. Construction was completed in 1977. The World Trade Centre towers were unusual because they used steel "column trees" for the outer structure, where the windows were, while the inner core, where the elevators were, was constructed using cast in-situ reinforced concrete. Most high-rise buildings in Malaysia are constructed using cast in-situ reinforced concrete. The steel used for the column trees was heat treated steel of type T1 with a melting temperature of around 600 degrees centigrade. The steel may have been annealed to provide greater ductility and to prevent brittle failure.

Information courtesy of Dr. W. Gene Corley, Hon. ASCE, SE, PE, Senior Vice-President of Construction Technology Laboratories (CTL), USA.

What the Eye Cannot See

2006-02-05T01:02:00.000+08:00

I learnt this from Albert's blog. Although our eyes can't see it, the digital camera is able to see the emission from a remote control. Below are three remote controls (clockwise from top left) being for the air-conditioner, a portable VCD player and Astro satellite TV decoder. The Astro remote control has two emitters while most remote controls only have one.

The digital camera can see what the eyes cannot see.

The Reverse Osmosis System

2006-02-04T14:26:00.003+08:00

The Reverse Osmosis (R.O.) System is available as an undersink unit.

The low pressure switch switches the pump off when there is no incoming water. The high pressure switch switches the pump off when there is high pressure because the tank is full and the faucet is off. The whole circuit is in series. If either the low pressure switch or high pressure switch is off, the solenoid valve is shut and there is no power to run the pump.

Water comes in through a saddle valve. The saddle valve is clamped onto the water supply pipe by two screws. Another screw is turned which lowers a very hard needle into the pipe. This punches a small hole, releasing the water into the saddle valve and tube. The water then flows into the R.O. machine.

The first stage is the sediment filter. This is usually 1 or 5 micron. The CSM filter has a roughly flat surface. The pleated filter such as CP-5 (5 micron) has pleats to increase surface area for better filtration.

The second stage is the Granulated Activated Carbon (GAC) cartridge. Carbon filters absorb bad taste, odour and chlorine. The carbon granules are housed inside a plastic cartridge.

The third stage is the Block Carbon. The CBR2-10 filter from Pentek U.S.A. has a 0.5 micron rating. It reduces 99.95% of Cryptosporidium and Giardia cysts. The block carbon cartridge can also prevent the GAC granules from entering the drinking water.

The R.O. membrane is stage 4. Approximately 50% of the water will flow through the R.O. membrane while the remainder is wastewater. A small hole is drilled under the water trap of the sink and the wastewater tube is inserted into this hole to dispose off the wastewater. The restrictor on the wastewater tube prevents all 100% of the water to flow out as wastewater. As the restrictor limits the flowrate on the waste line, the remaining water must flow through the R.O. membrane. The pump ensures there is sufficient pressure to force water through the R.O. membrane.

Stage 5 is the post carbon. The carbon granules are contained in a bullet like opaque plastic housing. The water is now ready to drink. There is usually an R.O. storage tank after stage 5.

The R.O. tank has a bladder inside it. Water is stored in the bladder. The tank can be "charged up" with air. This air pressure is between the tank wall and the bladder. Therefore the drinking water will spray out from the tank if the valve is opened. You can empty the tank without turning it upside-down to pour out the water. The tank can be placed under the sink and the air pressure will force the water out through the faucet on the sink above.

Things

2006-01-05T22:00:00.000+08:00

This is the Minolta Zoom 80 compact film camera. It has auto date and the option of a remote control (which I didn't buy) for shooting self-potraits while the camera is on a tripod. Purchased on 4 November 2003 for RM288, without the remote, from Minolta Marketing (M) Sdn. Bhd. at 1 Jalan 13/6, 46200 Petaling Jaya, Selangor, Malaysia.

Minolta Zoom 80 (front view).

Minolta Zoom 80 (top view).

Features:

Camera Type: 35 mm lens-shutter camera
Lens: 38–80 mm f/6–12, 5 elements in 5 groups
Focusing Range: 0.9 m–infinity (wide and tele)
Modes: Program Auto, Flash On, Flash Off, Infinity Lock (Flash Off), Remote/Self-Timer Mode using Program Auto
Film Speed: DX coded ISO 100/200 or 400, non-DX coded set to ISO 100
Shutter Speed: 1/1.7–1/430 s
Batteries: Two AA alkaline batteries

I bought this calculator for RM40 while working at Kuantan. Can't find it anywhere else here in Malaysia.

Texas Instruments scientific calculator.

My sister Li-lian, who presently lives in Los Angeles, USA, sent me this lomography camera. It has a super wide-angle fisheye lens for very interesting distortion shots.

Lomography camera.

My Nokia 3315 dual-band handphone. Cost RM335 when I bought it on 18 May 2003 from Ampang Park shopping centre.

Nokia 3315 handphone.

GP80 & CCF-302

2005-10-10T19:56:00.002+08:00

Below is a picture of the aluminium GP80 water filter. It uses a bag filter which is very effective.

GP80 Aluminium Filter.

Below is the CCF-302 which is a three stage filter. The first stage is the sediment filter, the second stage is the granulated activated carbon (GAC) filter and the third stage is the block carbon filter. The block carbon prevents the fine GAC from entering into the drinking water. A pump is not included with the CCF-302. It is possible to drink directly from the CCF-302 and boiling is not necessary.

CCF-302 Three-Stage Filter.

Fractured Tooth

2005-10-10T09:00:00.000+08:00

On 10 September 2005 I visited the dentist to have my tooth extracted. My tooth had fractured due to insufficient brushing. I was brushing my teeth once a day when it should've been twice daily. Lack of fluoride possibly caused the tooth to weaken and then fracture. Here are some photos showing the pus in the gums caused by food which had seeped into the broken tooth which was fractured from front to back and could be opened like a sandwich.

Photo 1: Gums started to swell. At this time I didn't know the tooth was fractured.

Photo 2: Swelling in front and behind the fractured molar.

Photo 3 taken 30 August 2005: The swelling gets bigger.

Photo 4 taken 30 August 2005: Pus started to seep out from the infected gums.

Photo 5 taken 31 August 2005: Swelling has increased and pus can be seen inside the gums.

Photo 6 taken 10 September 2005: The gums have swelled to the top of the tooth. I will be seeing the dentist today with dad.

Photo 7 taken 10 September 2005: The tooth has been extracted just a few minutes earlier and the gums look very raw.

Photo 8 taken 9 October 2005: One month after the extraction, the gums have healed.

Anaesthetic was used before the extraction. The doctor applied several injections, asking me if I felt numb. He said that the gums and right cheek should feel numb before he would extract the tooth. When the right cheek was numb, I informed the doctor, who then used a plier like instrument to very quickly detach the tooth from the gums. There was a thudding feeling but fortunately no pain. The tooth came out in 2 halves. I washed my mouth. There was alot of blood. I was given gauze to chew on to stop the bleeding. The anaesthetic gradually wore off but by then the bleeding had stopped.

Cats!

2005-09-30T22:05:00.000+08:00

These are stray cats which have come to live around the house.

The mother cat.

Baby kittens with colourful eyes.

Mother and baby.

Sucking for milk.