Bayesian approach for determination of drift hazard curves for generic steel moment-resisting frames in territory of Tehran

The objective of this paper is to determine the drift demand hazard curves of steel moment-resisting frames with different number of stories in territory of Tehran; this is done through the combination of the results obtained from probabilistic seismic hazard analysis and the demand estimated through the best probabilistic seismic demand models. To select the best demand model, in this paper, a Bayesian regression has been used for the statistical analysis of the results obtained from incremental dynamic analysis in order to estimate the unknown parameters of model and to select the best Intensity Measure (IM) parameter; also the probability of overall collapse of structures has been computed. Considering the efficiency and sufficiency of the models, the results indicate that the accuracy of models with one single IM is a function of the number of stories, consequently the current widely used model with spectral acceleration in first period as IM is not suitable for all structural heights. Furthermore, regarding the fact that it is difficult to prepare a seismic hazard curve for a combined IM, it seems that the best model can be found among models with two single IMs. In other words, the best model to cover all structural heights is the one with linear combination of spectral acceleration of the first and the second period. Furthermore, using different models to calculate the curves shows that regardless of the number of IMs, estimated demands strongly depend on the standard deviation of model.