Seismic displacement-demand and urban damage distribution: the impact of different methods on vulnerability assessment

This paper addresses seismic vulnerability assessment at urban scale. Particularly, it focuses on the differences in damage distribution obtained from the application of several simplified methods for displacement demand determination. The results obtained for two cities of Switzerland (Sion and Martigny) highlight the related impact. Displacement demands predicted using three simplified methods are compared with “reference” seismic demands obtained from non-linear time-history analysis (NLTHA). Comparing the urban seismic damage distributions from the three simplified methods with the one from NLTHA helps in understanding the reliability of displacement demand determination. The following three methods are compared: the usual N2 method, the Lin & Miranda proposal and an optimized version of the N2 method. These methods are evaluated based on the real seismic hazard (microzones), showing furthermore the importance of considering the real soil conditions in the general damage assessment.