Performance assessment and prioritization of mitigation approaches for pre-seismic code structures

The selection of an efficient mitigation technique from a number of alternatives to reduce the seismic risk of pre-seismic code school buildings is the main focus of this study. An on-ground survey of the school building stock in a large study area that extends for 6000 km² enabled the selection of four different benchmark structures. Detailed simulation models are developed for the selected benchmark buildings and 14 retrofit alternatives to define their performance criteria and assess their seismic vulnerability. The earthquake hazard of the study region is accounted for using a wide range of ground motions, representing two seismic scenarios pertinent to several medium seismicity regions. The relative seismic performance of pre-code buildings and different mitigation alternatives from a large number of dynamic response simulations up to collapse is described in terms of fragility curves as well as a proposed measure of response termed the overall performance factor. This measure of response along with the systematic seismic assessment approach adopted in this study enable prioritizing different retrofit alternatives based on their performance-to-cost ratios, which help to arrive at an efficient and cost-effective mitigation strategy for the implementation at the regional scale.