Evaluating the functional recovery performance of a 1970s non-ductile reinforced concrete shear wall building (2023)
As seismic design in Canada continues to evolve, many buildings designed to previous buildingcode editions are left to their own devices, creating a vulnerability in communities exposed to largeearthquakes. This thesis will examine the preparedness of communities in the lower mainland ofBritish Columbia in the event of a M9 megathrust earthquake. It originates from the CascadiaSubduction Zone, a seismic source off the west coast of Canada and the United States. The focusof this thesis will be on the seismic performance of tall, pre-1980s, reinforced concrete shear wallbuildings, which represent a large proportion of Vancouver’s tall buildings. A nonlineardynamic analysis of an archetype building fitting the mentioned criteria was carried out using shellelements in LS-Dyna. Furthermore, using the FEMA P-2018 rating system, a rapid screening tool that assigns a rating to indicate relative collapse risk for each building considered, a general picture of the risk these building pose to the community could be formed. In recognition that collapse safety is not enough to create a more resilient community, as part of this study, a recently developed framework called TREADS (Tool for Recovery Estimation and Downtime Simulation) is used to describe the performance of the building by following resilience-based performance measures. Results for the nonlinear assessment showed that the archetype building has a large shear capacity due to the large number of walls. However, it is very brittle, and fails abruptly at a low drift ratio. Nevertheless, the FEMA P-2018 showed that this case study building has a rating indicating a relatively low seismic risk. By contrast, the loss and downtime assessment of the building showed that performance would fall short of the target recovery state of shelter-in-place after a 475yr return period earthquake and the target downtime to functional recovery of 4 months. Since the analysis using FEMA P-2018 suggests that the archetype building would perform better relative to other similar buildings, detailed analyses are recommended for any buildings of this type.