EXPLICIT DEMAND MODEL FOR MULTI- STORY STEEL MOMENT RESISTING FRAMES

Probabilistic structural demand models are considered as an essential ingredient for a seismic fragility analysis. This concept is commonly developed using statistics which needcollecting data in large quantities. Preparation of such a data-base is often costly and time-consuming. In this paper, generic seismic drift demand model for regular-multi-story steel moment resisting frames is presented to eliminate the need of time-consuming analyses. The demand model defined as a linear function of intensity measure,the spectral acceleration at fundamental period  Sa(T1)  , in logarithmic space predicts overall maximum inter-story drift. In addition,the model is coupled with a set of relations to directly estimate unknown statistical characteristics of the model parameters. These relations are developed using a Bayesian regression technique to explicitly address uncertainties arise from randomness and lack of knowledge. The developed demand model is employed to perform Seismic Fragility Analysis (SFA) for three designed building. The accuracy of the results is assessed by comparison with the results directly obtained from Incremental Dynamic analysis as an alternative.