Structural rumbles in Abeokuta
Abeokuta, land of my birth, a picturesque city nestled on mountains and valleys. There, a building collapsed the other day. Could that incident have been prevented? My answer is a simple yes. One life was reportedly lost; many were injured too in that unfortunate incident. I hear that the state governor has directed that integrity tests be carried out on the collapsed building. That surely is medicine after death. An integrity test will only ascertain the quality of concrete in the structure. It gives no information regarding the structural design process, the competence of the design personnel on the project, the quality of supervision on the project, as well as quality control measures that were put in place during the execution of the project.
It is a state government project, so one expects some semblance of professionalism in the planning, design and execution of the project. I expect engineering consultants to have been involved in the design and supervision. The design process involves a visit to the site by the design structural engineer, a subsoil investigation of the site by a geotechnical engineer, a structural design philosophy formulated by the engineer, based on the engineer’s knowledge of the terrain and the outcome of the geotechnical survey, a general arrangement of the structural elements in the office, production of design calculations, drawings, and bar schedules, checking and signing off for construction. It is there and then that drawings and schedules are issued to site after the costs have been ascertained by a quantity surveyor.
During the construction process, the structural engineer visits the site periodically as and when required to check the reinforcement and materials being used for construction. Before casting concrete, the engineer inspects each element to be cast, issues a written instruction that he has checked the reinforcement and found same to be in agreement with the structural drawings, and gives the contractor the authority to cast the concrete element in question.
The reason for my rigmarole is to show that this time-tested approach is not always followed on many projects. Many Nigerian clients don’t have respect for the hardcore professionals. They prefer half-baked, ready-to-compromise professionals who tell them what they want to hear. Many structural engineers have walked out on some projects for this singular reason. Of course, a serious minded engineer will not partake in projects that are mired in shenanigans.
Many years ago, I designed a raft foundation for a client. From my calculations, a 300mm thick raft slab was required. When I went for inspection, the reinforcement “chairs” and spacers were arranged as specified. I gave approval for concrete cast. On the day the concrete was to be cast, I was not expected to be at the site, but I went, unannounced. What did I see? Instead of the 300mm concrete that was specified, the formwork and the reinforcement had been adjusted to give 250mm concrete! When I confronted the contractor, his excuse was that it was the client, who is not an engineer, that instructed him to reduce the slab thickness to 250mm, because the client felt that 300mm thick concrete was too much for a building on three suspended floors! I stood my ground and told the contractor to do the needful. Had the contractor or the client refused my instruction, I would have simply resigned from the project. That was a disaster averted.
A good engineer will reject poor materials whenever they are brought to site for concreting. He checks the sand delivered. Is it fine sharp sand or coarse sharp sand? A good engineer will make adjustments through trial mixes to achieve the required concrete strength. The steel delivered to site should be tested for strength, and the source of supply ascertained. You don’t talk about integrity tests when the damage has been done. Due diligence must be carried out as the construction progresses.
The production of quality concrete is not the prerogative of the supervising structural engineer. It is the duty of the contractor to put in place good quality control architecture. If this is not done, disaster looms. The contractor is expected to have some technical education and certification up to a certain level. But the Nigerian in us makes it possible for anybody to wake up tomorrow and says he or she is a contractor, and such people, with the right connections, get the juicy contracts.
How many people who call themselves engineers in Nigeria today have COREN certification? Go to any construction site, and you will see bricklayers, welders, electricians, auto mechanics, iron benders, carpenters, name it, all being addressed as engineers. Everything is in short supply except incompetence, greed and avarice.
The construction industry is now an all-comer affair, the door is open to quacks and charlatans. The retrogression in the quality of personnel in the construction industry is alarming, and for these reasons, more buildings and bridges will collapse.
We are waiting for the investigative panel set up by the Ogun State government.
Ige is a Structural Engineer based in Lagos