UGANDA, Kampala | Real Muloodi News | The Government of Uganda has prohibited the use of steel-timber concrete composite building technology, citing structural safety concerns.
The move is intended to ensure building safety. Engineers expressed enthusiasm for the choice, which they claimed many developers prefer since it is less expensive than the steel-concrete composite approach.
In a legislative instrument published on September 19 but gazetted on September 23, Works Minister Katumba Wamala stated:
“In exercise of the powers conferred upon the minister responsible for building operations by Section 42 of the Building Control Act, 2013, and after consultations with the National Building Review Board (NBRB) … the use of steel-timber concrete composite building method is not safe and is prohibited in any building operation.”
According to the Section, the minister may, after consulting with the Board, and “upon being satisfied that any method or material used in a building operation is not safe, by notice published in the Gazette, prohibit the use of that method or material in the building operation”.
According to the law, such a judgement may only be appealed in the High Court, and a person “who uses a prohibited method or material contrary to a notice issued under subsection (1), commits an offence and is liable, on conviction, to a fine of not exceeding forty eight currency points (Shs960,000) or imprisonment not exceeding two years, or both.”
Bageya Waiswa, Permanent Secretary of the Works Ministry, said that the restriction was prompted by conclusions in a report of a review conducted by the National Building Review Board (NBRB).
“They (NBRB) did a technical assessment and came to the conclusion that the method is dangerous. They filed a report that detailed the dangers. It is on that basis that the minister issued the statutory instrument,” he noted.
The PS, on the other hand, refuses to comment more, sending enquiries to the NBRB.
Mr Herbert Zziwa, the Board’s spokesman, verified the findings but declined to comment on the report’s specifics.
NBRB 2021 study
According to additional NBRB sources, a June/July 2021 investigation found that 80.5 per cent of structures under construction in Uganda’s capital, Kampala, and new cities did not comply with Building Control Act regulations, posing a risk to tenants.
The investigation focused on whether engineers and contractors followed authorised building designs and terms for providing occupation permits, the nature of professional engagements, and drainage system provisioning, among other things.
The researchers looked at 5,939 structures, including 2,606 finished buildings and 3,333 under construction.
“The overall compliance level of the active construction sites was at 19.5 percent, acquisition of building permit at 6 percent, supervision of the building by professionals 6 percent,” the study read in parts.
It is unclear whether the report produced regarding Kampala in October last year was the basis for the NBRB Board’s proposal to prohibit the use of steel-timber concrete composite building technology.
Mr Zziwa stated that the NBRB has a thorough technical report that it has to break down before delivering a public remark on the subject. Mr Zziwa stated that this declaration was made at a press conference on Monday, September 26th, 2022.
“… We are going to … give details and explain the study, recommendations and steps that can be taken for the existing buildings that were constructed using that method, what will be done to those buildings, and also going forward what should be done,” he said.
Engineers’ View
The Head of the Uganda Institute of Professional Engineers (UIPE), Mr Andrew Muhwezi, said Gen Katumba’s actions were aimed to prevent a “catastrophe” because “the strength of the structures (built using the said method) have been found wanting”.
“… many of them (buildings) have been collapsing. I think the minister’s legal notice is supposed to be like a mitigating measure to say, ‘please, let’s hold on and we first provide national guidance in this design arrangement and also train the different players so that we do not have continuous catastrophes,” Mr Muhwezi said.
The steel-timber concrete composite building system is a hybrid that has gained popularity in most of the Western world in recent years, but Mr Muhwezi claims it is being used without being subjected to local testing and requirements.
“Somebody went and benchmarked this kind of hybrid arrangement from somewhere and came and started piloting it on one site, then others picked the idea and replicated it across without local guidelines, without local standards or adaptation to international standards. What has been happening is, of course, catastrophe,” he said.
Contrary Truth
According to research conducted by the University of South West Sydney in Australia, lumber, as a lightweight and sustainable building material, may be utilised effectively in combination with steel and concrete to produce sturdy and ecologically beneficial structures.
Associate Professor Hamid Valipour, who studied hybrid/composite timber-concrete and steel-timber connections and structural systems, claims that the process is significantly faster than steel-concrete composite methods.
“Currently, buildings consist of reinforced concrete or steel-concrete composites, cast in situ. Concrete is poured into formwork and propping is then required for at least a week. This is a wait of at least 10 days between storeys. Building with steel-timber composites means there is no waiting and upward construction can be seamlessly ongoing,” he wrote.
However, Mr Moses Tiberwonda, an engineer who represents the Uganda National Association of Building and Civil Engineering Contractors (UNABCEC), claims that it is not the only way that ensures timely building.
“There are some other methods which are faster, but have not been used. Spear House [in Kampala, for instance] was constructed of steel. It is also faster and I don’t think it is as risky as this method. We should not start killing people because it is a faster method,” he argued.
Prof. Valipour contends in his research that in addition to being significantly lighter, the steel-concrete composite method lowers the risk of accidents, improves the effectiveness of moving, lifting, and placing panels, lowers the noise and pollution associated with construction activities, and makes it easier to recycle or reuse the composites.
How the Technique Has Been Used
Eng Tiberwondwa responded by saying that while the technique has received praise on a global scale, it is being used incorrectly in Uganda.
“We are talking about a situation whereby someone is using small universal beams and he is combining it with timber and concrete. When you look at the kind of construction it is like he is doing a ceiling, but he continues to the next floor,” Mr Tiberondwa said.
He added: “The way they join the horizontal members and the vertical members, that joint is very weak. When you are joining a vertical member and a horizontal member, industrial welding is one of the methods. The other one is using bolts. And in these buildings I have seen, bolts are not being used, the welding that we are seeing is very weak. It is not industrial welding. It does not pass the test.”
Structures built using steel-timber concrete composite are designed to last for 20-30 years, but the buildings are weak.
“If you get a tremor of any magnitude,” he said, “[the] buildings will not stand. You are putting the lives of people at stake.”
Earlier, UIPE President Muhwezi said the “combination of pillars is not a conventional structure,” adding that criteria must be established to guarantee that both designers and contractors create and produce strong structures, which has not been the case with structures built utilising the prohibited approach.
While the technique has been tested elsewhere, Eng Muhwezi believes there is a need for national direction and training of various actors in the building sector on the design arrangement.
Although it was impossible to pinpoint the precise number of structures built utilising the steel-timber composite technique, Tiberondwa claimed that such structures might still be upgraded to make them safe.
“The developed countries use that method because they have addressed the weakness in the method. Similarly, if we find a building and get people to understand the structural weaknesses, we can modify the areas where there are weaknesses,” he added.
Steel Concrete Vs Steel-timber Concrete Composite
When two or more materials are combined, often those with highly diverse construction-related qualities, a composite material is created. The two components combine to provide the composite with its special qualities.
According to Eng Moses Tiberwondwa, steel-concrete composites combine the compressive strength of concrete with the tensile resistance of steel to create a highly effective and lightweight unit that is frequently utilised for constructions like bridges and multi-story buildings.
Steel-timber He said that steel’s tensile strength, the lightweight, energy, and aesthetic qualities of timber, as well as the strength and rigidity of concrete, are all utilised in concrete constructions. The wooden beams are shielded from direct water contact by the concrete slabs. That is essential to guaranteeing durability.
Eng Tiberwondwa claims that the motivation to use the prohibited approach has been the comparatively low cost of building.
“It is generally cheaper because contractors move away from the use of huge volumes of steel required in the making of reinforced concrete and steel structures that are necessary when you are using the steel-concrete composite method.
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