Performance and safety assessment of steel structures in substations using nonlinear time-history analysis

Electrical substations control voltage and the flow of electric energy, assuring optimal electricity transmission from generation plants to users. A detailed performance evaluation of the substation's structures is crucial to deciding whether to demolish or repair. This study analyzed a 200 KV substation's steel structure in China to find an efficient assessment strategy. Structural data and dimensions have been carried out through a holistic site inspection. Different laboratory tests have been conducted to evaluate the material's strength. The finite element method (FEM) has been utilized to develop the structural model, and nonlinear static and time-history analysis has been done with STAAD.Pro-2023. To assess the structural safety of the steel structure, necessary factors such as time-frequency, mode shape, deflections, and strength capacity ratios were studied. Structural data was found from structural analysis, and the Structure's present condition was compared with its initial conditions and allowable limits. The study's findings show a 15% reduction in natural frequencies and extended structural periods, indicating material degradation and potential reductions in dynamic resilience. The strength capacity ratio of the steel structure members was lower than the initial condition.