Economic Loss Assessment of Short-Period CBF Buildings with Varying Footing Sizes

The main goal of current design codes is to ensure the safety of people inside buildings during severe earthquakes. However, this objective must be achieved without excessive initial construction costs, and there is also a growing awareness within the earthquake engineering community of the importance of repair costs following a damaging earthquake. While the objective of different codes is reasonably consistent, various approaches are pursued to achieve this intent. The design of footings is a striking example of diversity in approaches. While the US code allows engineers to design for the reduced seismic design load, the Canadian code promotes designing footings based on the expected capacity of the seismic force-resisting system (SFRS). This discrepancy in codes can result in significant differences in footing size, potentially affecting the building performance. Hence, examining the repair cost of low-rise buildings could offer valuable insight into how the footing size impacts the seismic performance of these structures. In this study, a two-story building located on a class D site in Vancouver, Canada, is evaluated to assess the effects of the footing size on the expected seismic repair cost. This office building has an X-bracing system as the SFRS in the studied direction. Advanced numerical models are employed in OpenSees to simulate the building. The building repair costs are compared at the design ground motion intensity level, with reference to the relative significance of losses due to collapse, demolition, structural, and nonstructural losses. The results of this study suggest that for low-rise CBF buildings on soft soil, the best balance between initial costs and expected seismic losses appears to be near the size of a not capacity-protected (NCP) footing.