How Soil-Structure Interaction and Footing Size Affect Seismic Repair Costs of Low-Rise Concentrically Braced Frames

Building codes emphasize capacity design for superstructures, but seismic design provisions for foundations vary widely. US codes allow reduced seismic loads for footings, leading to significant movement, while Canadian codes often require capacity-protected footings with minimal movement. This study examines the effects of soil and foundation on short-period concentrically braced frame (CBF) buildings, focusing on footing size, seismic behavior, and economic loss. Results show that soil-structure interaction (SSI) can reduce expected annual loss but may increase collapse probability. Therefore, building codes should account for controlled foundation motion in design to optimize both structural performance and economic resilience.