NIStructE: Structural Distress Led to Collapse of 21 Storey Building in Ikoyi

Bennett Oghifo

President, Nigerian Institution of Structural Engineers (NIStructE), Dr. Kehinde B. Osifala has said that structural distress, and serious inadequate engineering and management of several of the design brief changes on the project led to the collapse of the 21 storey building in Ikoyi, Lagos, recently.

Osifala, who stated this at a media briefing yesterday, as some of the major preliminary findings of an investigation conducted by the institution at the site of the collapsed building, said “It is our view that the outcome of our preliminary investigation will give a general indication of what likely led to the unfortunate incidence.”

He said “that this incident is a structural engineering disaster is certainly not in doubt, however, events of this nature and structural engineering problems in general, require careful and painstaking analysis and assessment of all the evidence and information relating to the collapsed building and the site, including the resulting debris, eye-witness accounts, and all other available details before arriving at a definitive statement.”

He said the Nigerian Institution of Structural Engineers (NIStructE), the professional body entrusted with the responsibility for Structural Engineering practice in Nigeria, immediately assembled an investigation team to visit the site and carry out a Preliminary Assessment of the incidence, and prepare an appropriate preliminary report.

He state that “it is important to emphasise that the practice of structural engineering is an elaborate science involving the application of numerous scientific principles and it is therefore seldom likely that accurate conclusions can be rushed without first carrying out the prerequisite investigations, testing, and computations. Our institution refrained from making speculative comments until now when our findings from the preliminary investigation are available.

“We are now in a position to make factual statements and provide guidance to the general public that will hopefully be enlightening but also reassuring that structures once well designed and implemented with the use of the appropriate professionals should remain safe throughout their service life.

Giving a summary of the findings of the preliminary investigation, the NIStructE president said, “There are clear indications of several design brief changes on the project and the engineering and management of these changes appear to have been seriously inadequate.

“The building that collapsed was initially designed for just six (6) floors, and later to Twelve (12) floors, before this was further changed to Fifteen (15) floors. It could not yet be established the adequacy of any properly designed and documented further revision to the eventual (and tragically, final) Twenty-One (21) floors that was being implemented and which collapsed.

“There are also indications that more than two (2) structural engineering design firms worked on the project at different times.”

He said the preliminary investigation also revealed some evidence of structural inadequacy in the construction and that signs of some structural distress had already started to show within certain elements of the building.

“Some remedial measures were already being undertaken to address some of this. The method of implementation of this was not in accordance with sound Structural Engineering practices,” he said.

According to him, “Lack of proper quality control and quality assurance measures and processes during the construction was evident, becoming noticeable as seen in the poor-quality of concrete materials and workmanship observed during the examination of the collapse debris.

“All the above findings, which are very significant from the structural engineering point of view, need to be investigated further during the detailed investigation stage so that all factors related to the cause or causes of the collapse can be truly established and the appropriate lessons identified and implemented.

“We expect that the various committees that are being set up will have full access to much more information (such as all the structural drawings, the calculations, documents prepared and submitted for planning approval and for construction, material test results, site instructions and records, records of meetings, more eyewitness accounts, etc.).

He also discussed their appraisal of the other two blocks on the site of the collapsed building, stating that “In the light of the already gathered preliminary information about the observed inadequacies of the collapsed building, as well as the possible destabilising effects of the collapse on the adjoining and nearby buildings, it is imperative that a thorough and comprehensive structural integrity appraisal be carried out on the other two (2) buildings (14 and 15 storeys Respectively) on the same site.

On the need for structural integrity appraisals and engagement of competent professionals, he said, “This sad, but usually preventable, event of yet another building collapse, has resulted in a sudden surge of many property owners and occupiers requesting for Structural Integrity Tests to be carried out on their properties.”

The Nigerian Institution of Structural Engineers, in continuation of its advocacy efforts, advised the general public to “engage only competent and capable registered professionals on your projects and for these assessments. Structural Integrity Appraisal is a specialist knowledge and experience-based aspect of Structural Engineering, and to be sure of the accuracy and applicability, it is extremely important that the appraisal is carried out by qualified and registered Structural Engineers who have the requisite experience.

“In recent times, the term ‘Structural Integrity test’ has become more of a common slang which is not in any way fully accurate for the desired purpose. There is no single test that can determine the structural stability of a building or structure. Instead a ‘Structural Integrity Appraisal’ is not just limited to carrying out some non-destructive tests to evaluate the properties of the concrete, but is a comprehensive and all-inclusive structural engineering evaluation of the entire structure which is tailored to suit the full objectives of the appraisal. It is only after this that a clean bill of health can be confirmed for the building.”

The Institution, he said has “a register of its registered members and can be consulted on any matter of structural importance or concern.”

“As these findings remain preliminary until the recommended comprehensive investigation is carried out, and the outcome of the various Govermental and institutional panels have been determined, we should not in any way jeopardise the outcomes of the more detailed investigations being organised by various professional and regulatory bodies,” Osifala said.