Dynamic seismic risk assessment of personnel entrapment at the building level in urban areas

The location and number of earthquake-induced trapped people (ETP) in ruined buildings are critical for postearthquake search and rescue (PESR) operations. Current earthquake-induced personnel entrapment risk (EPER) assessments suffer from low spatiotemporal resolution, limiting their application in PESRs. Taking three subdistricts of Tianjin as the study area, an EPER assessment framework with high spatiotemporal resolution was proposed, with the building damage predicted through nonlinear time-history analysis. The personnel entrapment rate (PER) and number of ETP are subsequently calculated via series analysis of census data spatialization, the personnel evacuation rate and self- and mutual-rescue rate estimation at the building level. The results show that the framework effectively characterizes spatial heterogeneity and temporal dynamic changes in EPER, with the PER on workdays ranging from 0.17% to 0.38% and 0.22% to 0.38% on nonworkdays. Diurnal patterns revealed higher PER during the nighttime than during the daytime and elevated risk on nonworkdays. Compared with traditional methods, this framework improved the prediction accuracy of EPER by 12.9% to 47.9% across time periods. Considering the uncertainties of the input parameters, the average relative errors of the ETP are between −36.2% and 27.5% across time periods. With high spatiotemporal resolution and enhanced identification efficiency for priority targets, the framework can provide substantial technical support for PESR operations.