E DEPARTMENT OF CIVIL ENGINEERING

Building collapse remains a persistent challenge in urban areas across Nigeria, with Benin City experiencing a notable frequency of structural failures. It is a devastating phenomenon that leads to the destruction and loss of property and lives This paper represents a study on the hierarchical assessment of the underlying factors causing building collapse in the city of Benin. Utilizing a multi-criteria decision-making approach, the research categorizes and ranks the causes based on expert interviews, field observations, and documented case studies. Key factor examined include poor construction practices, substandard materials, inadequate regulatory enforcement, design flaws, and environmental influences. The hierarchical assessment process employs the use of structured questionnaire to gather data from professionals in the construction industry and ranks these causes based on the most voted factors into primary, secondary and tertiary factors revealing poor construction materials, inadequate supervision and regulation, corruption, poor workmanship and repurposing of buildings to be the most primary factors. Lack of proper engineering design, overloading, poor foundation work, weak enforcement of building codes and member failure to be secondary factors. Negligence and lack of maintenance, rapid urbanization and natural disasters to be tertiary factors. Recommendations to curb or reduce the issue of building collapse in the city of Benin are strict enforcement of building codes and regulations, quality control and material testing, enhanced professional training and certification, combating corruption, public awareness campaign, urban planning and zoning regulation, promotion of preventive maintenance, establishment of a building collapse response task force, encouraging use of technology in construction.

The study was carried out to analyze the settlement behaviors of fine-grained soils-that is, clayey soils-in Benin City, Nigeria, with a view to understanding their geotechnical
characteristics and compressibility under loads. Justification for this research lies in the
frequent structural failures and foundation instabilities observed in clayey sub-soils
across the region Various soil samples collected from the University of Benin and environs were tested for their physical and engineering properties in the laboratory. Standard tests such as moisture content, specific gravity, particle size distribution, Atterberg limits, and
consolidation, in line with ASTM and BS standards, were carried out to study soils' compressibility and settlement behaviors under applied loads. The natural moisture content of the soils varied between 18.6% and 22.4%, while the average specific gravity was 2.57. In addition, the Atterberg limits gave a liquid limit of 38-42%, plastic limit of 22-23%, and plasticity index of 16-19%, classifying the soils as
inorganic clays of low to medium plasticity CL under the USCS and A-7-6 under
AASHTO. More than 50% of soil particles passed the 0.075 mm sieve, which confirms
fine-grained, cohesive soils that are characteristic of the Benin Formation. The results of
the consolidation (oedometer) test show that settlement increases with applied pressure
between 12.5 kPa and 250 kPa, whereas the coefficient of volume compressibility, Mv, decreases from 0.1× 10 −3 and 1.0× 10 −3 m2 /kN, indicating moderate to high compressibility. Generally, these soils are characterized by moderate plasticity, low permeability, and high settlement potential; hence, foundation designs should consider soil stabilization, preloading, or raft and pile foundations, with adequate drainage control to ensure long-term stability