Influence of Concentrically Braced Frame Footing Design on Recovery Time

The primary objective of current seismic design codes is to ensure the life safety of building occupants under extreme seismic events. These codes normally permit structural and nonstructural damage during a design-level earthquake, leading to the possibility of significant economic losses and recovery time for the building. Recovery time is a significant factor in the seismic performance of buildings because it affects not only the owner and users of a building, but also the overall recovery of the community. In designing low-rise buildings, current design requirements in different jurisdictions can produce footings with vastly different sizes, which can significantly affect building performance. Therefore, there is a need to investigate the effects of footing size on the expected recovery time of low-rise buildings.In this study, 2-storey concentrically braced frame buildings at a site class D are selected to evaluate the impact of the size of the footings on the repair time of low-rise buildings. These buildings are in Vancouver, Canada, and have X-bracing systems. The buildings are modelled in OpenSees using an advanced numerical model. Nonlinear response history analysis is performed employing a set of ground motions that match the soil condition of the site. The recovery time is estimated, including the delay time to start repairs and the time required to repair the damaged members. The findings of this study suggest that not capacity-protected (NCP) footings (i.e., rocking foundations) could be the preferred choice for short-period CBF buildings on soft soil.