Original Development of a Reliability-Based Structural Assessment Framework for Reinforced Concrete Building Frames Under Multiple Hazard Exposure in Nigeria

Reinforced concrete building frames in Nigeria are exposed to multiple hazards including earthquake ground shaking, wind loading, flood inundation, and construction quality variability, which jointly determine structural performance but are assessed independently in current practice. This study develops an original reliability-based structural assessment framework for RC building frames under multiple hazard exposure in Nigeria, constituting the first probabilistic multi-hazard structural performance assessment methodology calibrated to Nigerian design and construction practice. The framework development encompasses four original contributions: a Nigerian construction quality variability model derived from a comprehensive survey of as-built geometric and material property deviations across 80 RC frame building construction projects; probabilistic hazard models for wind, earthquake, and flood for six representative Nigerian urban locations, including the non-stationary flood frequency model; a fibre element nonlinear dynamic structural analysis model capable of joint capacity assessment under multiple loading types; and a joint probability multi-hazard failure model using Bayesian network representation of correlated failure events. The framework is applied to the multi-hazard reliability assessment of four representative RC frame typologies under six urban location scenarios. Results reveal that earthquake and wind hazard interact to reduce multi-hazard reliability by 15 to 22 percent below the component hazard minimum for modern 6-to-12 storey frames. Construction quality variability is the dominant reliability modifier for 1-to-4 storey frames. The framework enables informed risk-based decision making for building policy, insurance, and investment in Nigeria.

Keywords: reliability assessment, reinforced concrete frames, multi-hazard, structural performance, Nigeria