High-resolution post-earthquake recovery simulation; impact of safety cordons

A framework is proposed to assess the impact of safety cordons on the recovery of community functions after an earthquake, using high-resolution geospatial information to simulate the damage, cordons, and recovery trajectories for buildings in the affected area. Ground motion maps are developed to characterize shaking intensities for regional building-level engineering assessments of damage, repair times, and recovery times to quantify the impact of access restrictions associated with cordons around tall buildings with impaired collapse safety. The results are presented as recovery curves that quantify the cumulative loss in building functionality across the community as a function of time following an earthquake. A case study considers recovery of office space in Downtown San Francisco, following a Mw7.2 event on the San Andreas Fault. For this scenario, an average of 219 community days of office functionality are lost in the first year, representing about 60% of the total office space capacity. About one-third of the loss is attributed to access restrictions associated with cordons around older tall buildings. The proposed framework can be used to investigate the efficacy of various mitigation strategies to expedite recovery. While the most effective strategy for mitigating the overall impact of cordon restrictions is to seismically retrofit older tall buildings that trigger cordons, other less expensive preparedness measures are shown to be effective, depending on the recovery time frame of interest. Specifically, recovery preparedness measures are generally more effective when evaluated for longer-term recovery targets (e.g. recovery of function after 12 months) compared with short-term targets (e.g. recovery after 4 months).