Failure Analysis of a Partially Collapsed Building using Analytical Hierarchical Process

Abstract

Building failure usually results in collapse if not discovered and properly addressed. Building collapse/failure most times causes loss of properties and lives. A case study of a partially collapsed one-story building is presented for emphasis with technical assessment of the partial-collapse cause so as to proffer remedy of the structure. This is achieved through detailed engineering analysis of the building’s structural elements and identification of remedial options. Field inspection is carried out through soil excavation to assess the foundation condition, taking soil samples from the collapsed building for laboratory study and nondestructive test. From inspection, it was observed that the building construction was inadequately supervised and as a result was under-reinforced, which led to excessive cracks and deflection. The soil is classified by AASHTO A-2-4: maximum dry density 2.15 mg/m3 and optimum moisture content 9%. The compressive strength of the structural elements was measured using the rebound hammer, and a mean compressive strength of 13 N/mm2 was obtained which indicates a low-compressive-strength concrete. Analytical hierarchical process is utilized as the multi-criteria decision-making method to derive the actual partial-collapse cause; from the priority vector 6, 56, 26 and 12% were obtained for soil/foundation, under-reinforcement, low-compressive-strength and overloading alternatives, respectively. The consistency ratio computed was 0.065 which shows the decision maker’s subjective assessment was consistent. The summary of the failure investigation underscored the importance of ensuring proper supervision and quality control for framed-structures construction.