Seismic risk management of existing reinforced concrete buildings in the Cascadia subduction zone

Through evolution of building design codes in active seismic regions, life safety performance limit state has been met. Unacceptably high economic loss during the 1994 Northridge and 1995 Kobe earthquakes, however, has brought forward a new design paradigm: performance-based earthquake engineering (PBEE). In this study, the PBEE is extended to study: (i) effect of three earthquake types, namely shallow crustal earthquakes, deep inslab earthquakes, and mega-thrust Cascadia interface earthquakes, on loss assessment; (ii) consideration of mainshock-aftershock (MS-AS) sequences as earthquake excitation; and (iii) multi-variate seismic demand modeling for multi- criteria seismic performance evaluation. This is applied to a 4-story non-ductile reinforced concrete frame located in Victoria, British Columbia, Canada. Through this case study, it is highlighted that the sources of ground motions have significant effects on loss assessment. Furthermore, influences of MS-AS earthquake sequences and multi-variate seismic demand models on the expected seismic loss ratios are in the order of 10%. In light of this, for any future seismic risk management, it is proposed to have an evolutionary assessment framework that is adaptive to the current state of scientific knowledge and evidence.