ABSTRACT
Buildings designed and constructed in accordance with the today code provisions are expected to withstand frequent hazards without structural damage and to prevent collapse under rare events (e.g., strong earthquakes). However, there are also situations where multiple or cascading hazards can occur, e.g., earthquake aftershocks or fire after earthquake. In such cases, even if the structure survives the first event with minimal damages that do not affect the global stability, the subsequent events can severely damage critical members and potentially cause extensive damages or even failures. The study presented in the paper investigates the response of a typical steel frame structure under cascading scenarios that involve damage to both lateral and gravity load resisting systems. The parameters considered in the study are the initial design conditions (level of overstrength in members), load scenarios (single/multi hazard events), and residual capacity after first event. Numerical models were calibrated against relevant test data. Results indicated appropriate resistance for single and multi-hazard loading scenarios. Even the structure showed adequate progressive collapse resistance, the internal column loss scenarios drawn attention, as they led to extensive damage in the perimeter moment resisting frames, which were still undamaged after the earthquake. It is expected that the multi-hazard design can be used to obtain more robust building structures against extreme loading events and improve the life-cycle performance of built infrastructure.
