ABAQUS-Based Failure Mode Analysis of a High-Traffic Pedestrian Bridge: Stress, Yielding, and Corrosion Effects in Lagos, Nigeria

The structural integrity of pedestrian bridges is crucial for ensuring public safety, particularly in high-traffic urban areas. This study presents a finite element analysis (FEA) of the Ojota Pedestrian Bridge in Lagos, Nigeria, using ABAQUS software to assess its loadcarrying capacity, material behavior,and potential failure modes under various loading conditions. The objective is to evaluate the bridge's performance under service and extreme loads and to provide insights for maintenance and safety improvements. A 3D finite element model of the bridge was developed, incorporating accurate material properties, boundary conditions, and realistic load scenarios such as pedestrian-induced forces and environmental effects. The model simulated the interaction between structural components, allowing for detailed stress and deformation analysis. A separate corrosion analysis was conducted to simulate longterm material deterioration, assessing the impact of reinforcement loss on structural behavior. The results highlighted two primary failure mechanisms: reinforcement yielding and concrete crushing. Reinforcement bars reached their yield strength of 500 MPa, especially at mid-span and support regions, indicating potential permanent deformation under excessive loading. Similarly, compressive stress in concrete exceeded its design strength of 30 MPa, suggesting crack formation and localized crushing. The corrosion analysis revealed that a 50% reduction in reinforcement area led to excessive deflections (27.5 mm), surpassing the 22.5 mm serviceability limit and indicating structural instability. The study concludes that while the bridge remains stable under normal conditions, long-term degradation and overloading could compromise its safety, warranting reinforcement optimization, corrosion prevention, and regular monitoring.