Chapter One – Pre-stressed Concrete Post-tensioning System

The accounts below are my efforts in bringing new engineering technologies to Malaysia and their effectiveness in improving the engineering services in Malaysia during the two and a half decades when I was active in business.

After Malaya gained its independence from the British Empire in 1957, it started the process of "Malayanisation" in which British officers serving in Malaya were slowly being replaced by Malayans.

By the time I graduated from University Malaya with a civil engineering degree in 1965 and joined the Public Works Department (PWD) a year later, most, if not all the British engineers had been replaced. Ostensibly, what the British had left behind (in PWD) was the legacy of an administrative system that was most appropriate at the material time but unfortunately it also left a conservative mentality amongst the engineering professionals who were doggedly reluctant to accept new engineering technologies.

As a young and enthusiastic engineer working in PWD during the second half of the 60s I was rather frustrated for not been given the encouragement to make innovations and changes in the design of bridges. 

When the original Bota Bridge, designed by PWD's expatriate engineers in the mid 60s using 40ft pretension girdles, was destroyed by flood in 1970, I was working as a time-scale design engineer in Airport Section of the Design & Research (D&R) Department in PWD headquarters. Though D&R Department then had a Bridge Design Section, for some unknown reasons, the redesign of the washed-away Bota Bridge ended up in Airport Section!           

In the redesign of Bota Bridge in Perak I was assigned to determine the cause of its collapse and come out with a viable proposal. I was left completely on my own to carry out hydrological and subsurface investigations. From these investigations and further studies carried out by me, it was indisputable that the original design of the bridge was totally inadequate to even cater for a flood frequency of 1-in-5-year. (Note: the flood frequency of 1970 was estimated as 1-in-50-year.) The bridge was totally submerged during the 1970 flood, its pier spans of 40 ft was insufficient to provide for the free flow for debris brought down by the flood from upstream and the piled-foundation was too shadow to cater for the riverbed scour during the food. My proposal was to construct a bridge with a minimum pier span of 140 ft. with its deck arising at its abutments above the 1-in-50-year flood to above that at its mid span and a foundation supported by piles with an imbedded length of 40 ft or more. The total length of the bridge would be about 1,400ft. But it was only after a long and tedious effort of convincing the high-ups in PWD before my concepts of the design were reluctantly accepted.

I was responsible for the design of the substructure and my colleague, the late KD Chang, the superstructure. Based on the geotechnical information from the subsurface investigations carried out earlier, bored piling was the most appropriate for the bridge’s foundation because the substrata consisted mainly of dense granular materials. But unfortunately bored piling was something new then and not a single piling contractor had the appropriate equipment to do it! The only option was to use open-ended steel piles. I proposed two types of steel piles; a welded piped pile and a welded twin H-pile. The test piles were ordered from Hume Industries and a tender was called for driving and testing. The piles were designed to take a working load of 200 tons each and a test pile was to be tested to twice the working load, i.e. 400 tons. But at that time, the maximum capacity of hydraulic jacks available was 200 tons. Therefore a testing procedure had to be devised to take into account this limitation and the existing conditions at the site. I proposed to use a steel girder placed over the test pile forming a T structure. A 200-ton jack would be placed on one end of the cantilever to jack against a kentiledge of 200 tons and the other end would be propped against another kentiledge of 200 tons in order to impose a load of 400 tons on to the top of the test pile. To accommodate this testing procedure, it was important that the location of the test piles had to be selected so that part of the remaining bridge deck not washed away by the flood could be used not only as a platform for the piling machine but also to provide adequate kentiledge for the tests. The tests were successfully conducted and the piped pile was selected as it was more economical and could be locally fabricated.

After the completion of the pile tests, Chang and I proceeded to complete the design and tender documentation of the bridge. I was also assigned to compile all design calculations and drawings when the designs of the sub and super structures were completed. In the design of the superstructure, we were instructed to use the post-tensioned 102ft girdle.      

When I first joined PWD in 1966, pre-stressed concrete construction was in its infancy. It was used mainly in precast pretension girdles for bridge construction with a maximum length of 40ft. The first precast post-tension bridge girdle was 102ft long designed by an engineering consulting firm in Kuala Lumpur, appointed to design two major bridges in Muar and Batu Pahat in Johor. Upon the completion of these two bridges, the 102ft post-tensioned girdle was adopted as a PWD's standard design.         

As a young and inquisitive engineer, I wanted to know more about the prestressed concrete design and requested the head of the Bridge Section (KC Lee) for the design calculations and drawing of the 102ft post-tensioned girdle. But I was pointedly told to use the drawing without question as I was told the design had gone through a thorough check by some experts in PWD.

Not satisfied, I carried out on my own a detailed design calculation of the 102ft girdle and discovered that it was under-designed based on a more stringent loading condition as specified in the relevant British Standard, used in the design of bridges in Malaysia. And I also noticed that the girdle was designed using a specific prestressing system (BBRV)!

I reported my findings to my superiors and submitted to them all my detailed calculations. Again, it was after a long and tedious explanation, especially with KC Lee, that the higher-ups in PWD HQ, including the DG (LT Thian) finally accepted my exertion that the existing 102ft post-tensioned girdle was under-designed. I was then told to rectify the deficiency of the existing drawing of the 102ft post-tensioned girdle.

It was a simple matter; what I did was, maintaining the cross-section of the girdle, just increased its bottom flange by a few inches! Two sets of steel moulds for the 102ft girdle were in the procession of PWD after the completion of Muar and Batu Pahat bridges. With the simple amendment to the design, the moulds could also be easily modified. In the meantime, while redesigning the girdle, I did a bit of research on other prestressing systems available in the world then. I discovered that there were, besides BBRV, other established systems like Freyssinet, VSL and CCL were widely used in many developed countries. Not to favor any system, the redesign did not specify a system to be used, but the profile of the resultant tensioning tendon and force required for the girder were specified. A sub-contract tender document for the supply and implementation of the post-tensioning work was prepared.

When all the designs, drawings and tender documentations were completed I felt it was a good opportunity for me to get involved in the site supervision and contract administration of the construction of the bridge. For nearly five years working as an engineer after graduation, I had spent most of my time in the design office. It was time now to get some solid experience in the construction site to make me a better all-round engineer. With this in mind, I approached the DG of PWD who had shown great interest in the re-design of Bota Bridge, and requested for his permission to appoint me as the resident engineer (RE) for the construction of the bridge. I further asked him to transfer me back to the HQ after the completion of the bridge as I would be an asset to the D&R Department. He agreed to appoint me as the RE but told me pointedly that he could not transfer me back to the HQ after the completion of the bridge because as a RE, I would have to be transferred to the State of Perak as a state officer and thereafter I would be under the State’s jurisdiction to be transferred anywhere they thought fit. It was obvious that for what I had done, he was not even prepared to lift a finger to help but instead took pleasure in pouring cold water over my good intention.        

For this reason I decided to quit PWD. But to quit was not a simple matter because I was already married and had a family to feed. I pondered over what I wanted to do for my future, and I had a choice to be a consulting engineer or a contractor. Also, with my experience I could easily find employment in a consulting engineering firm or a contracting company. But after being employed for over five years, I thought I should try to venture into something on my own and to stand on my own two feet. And that was exactly what I finally decided to do – one foot in operating a consulting engineering practice and the other in a specialist contracting outfit!         

There would be no problem to start a new consulting engineering practice as there were not many in existence then. But to venture into a specialist contracting business, I needed to have in my possession something that was new and had room for expansion. That was something that I had in my hand before I decided to quit PWD.

From my limited research on the various patented of prestressing systems available, I found that Freyssinet system was the first to be introduced in the early 1940s and was widely used throughout the world. It was developed by the French, but a British company, PSC Equipment Ltd. had the exclusive right to manufacture the Freyssinet products in the UK and market them all over the world. When I was re-designing the 102ft pre-stressed girdle I wrote to PSC Equipment Ltd. making enquiries about their products and informing them about the recent application of pre-stressed concrete in bridge construction in Malaysia. They were positive in their response and were prepared to establish their presence in Malaysia. I was invited to visit them in the UK to discuss the matter further.

Confident that my coming meeting and discussion with PSC Equipment would be successful in bringing the Freyssinet post-tensioning system to Malaysia, I set up, without any hesitation, a company called Prestressed Concrete Structures Sdn Bhd in September 1970. This company would hold the exclusive agency for the Freysinnet system and undertake post-tensioning works in Malaysia. I left the composition of the shareholders in the company to be decided later as I had to take time to look for suitable partner/s.

Before the end of Oct 1970, Chang and I completed all drawings and tender documentations for the construction of the piling and super-structural works of the bridge including the tender for the post-tensioning sub-contract. Immediately thereafter I took 2-week’s leave to go to London to meet PSC Equipment Ltd to finalize the business of promoting the Freysinnet system in Malaysia. I flew by Aroflot, the cheapest airfare to London with a stopover in Moscow. It was my first oversea trip by air and with an over-night stop in Moscow, it was also my first time to see a snowfall. I arrived London Heathrow on 26 Oct 1970 and the Sale’s Director of PSC Equipment, Tom Marquis, was at the airport to receive me.            

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