Benefit-Cost Analysis for mitigating seismic losses: Probabilistic evaluation of retrofit measures for residential buildings in Turkey

摘要

In the wake of the destructive 1999 earthquakes in Turkey, the urgent need has arisen to evaluate the benefits of loss mitigation measures that could be undertaken to strengthen the existing building stock. For this purpose, a cost benefit analysis for the implementation of various seismic retrofitting measures is performed on a common and vulnerable type of apartment building located in Istanbul. The analysis is performed probabilistically through the development of fragility curves for the structure in its different retrofitted configurations. The fragility curves are developed analytically through Monte Carlo simulation techniques involving time-history response analyses of the respective nonlinear finite-element models. By incorporating the probabilistic seismic hazard for the region, expected losses are obtained for arbitrary time-horizons. By including realistic cost estimates of the retrofitting schemes and costs of direct losses, one can estimate the benefit of the retrofitting measures in present day values. A sensitivity analysis is performed to determine the effects of varying cost parameters and also the assumed cost of human lives. The analysis implies that, even when considering only direct losses, all of the retrofitting measures considered are very desirable for all but the very shortest of time-horizons. The methodology developed here can be extended to an entire region by incorporating additional structural types, soil types, retrofitting measures etc.