influence of reduced seicmic hazard level in rehabilation considering remaining life span

In the seismic evaluation and retrofit methodology proposed by fema 356 and seismic rehabilitation of existing buildings no.360, the selected seismic hazard level is a 475-year return period earthquake with a probability of occurrence 10% in 50 years expected remaining lifespan for an existing building, while expected remaining existing building life span is much less than 50 years. hence, reducing the seismic hazard level is used to enable cost-effective seismic evaluation and retrofit of the existing building. the current study base on the equivalence of probability of exceedance between existing and new building recommend seismic hazard reduction factors. then, the existing building is retrofitted for the reduced seismic hazard level. a validation procedure is proposed to investigate the objective performance of a nonlinear sdof system based on using the probability of a limit state. the limit state probability is a probability that a specific limit state occurs during the building lifespan. the results show that considering reduced seismic hazard level according to the remaining building lifespan can be permitted in conjunction with appropriate lower bounds of the remaining building lifespans.