Engineering Failure Analysis of a Failed Building in Osun State, Nigeria

This paper assesses the causes and socioeconomic impact of some recent cases of collapsed buildings in Nigeria. Information on selected collapsed buildings was collated, and a case study of a failed one-story building is presented for emphasis. A summary of the technical assessment and remediation of the building was presented as well. Both field and laboratory work involved close inspection of the building, excavation to reveal the condition of the foundation, taking samples of slabs and beams from the collapsed building for laboratory study, detailed structural analysis, a design analysis of the structural elements of the building to reveal causes of failure, and identification of remedial options and recommendation. Solubility of concrete in acids was used to assess the quality of concrete used. This study revealed that a lot of lives and properties have been lost in the various collapsed buildings, and these losses have negatively impacted the socioeconomic status of Nigerians. The results of the case study revealed that the main structural components (slab, beam, column, and footing) of the building were not properly proportioned and were seriously underreinforced, which led to excessive deflection. Additionally, concrete mixes used in the construction were found to be weak, and walls that should have been non-load-bearing ended up carrying loads and induced a hogging moment onto the slab for which reinforcement was not provided. The solubility tests showed that the ratio of calcium concentration of concrete mix used in the collapsed building to that of standard 1:2:4 concrete mixes were 0.03, 0.20, and 0.73, respectively. These low ratios indicate that the cement portion in the concrete was not adequate, and it was concluded that the concrete samples from the collapsed building contained less calcium than necessary for structural success. The summary of the assessment underscored the need for ensuring quality control and proper supervision in the construction of reinforced concrete structures.