Investigation of the Effect of Uncertainty of the Ibara-Madina-krawinkler Model Parameters on Seismic Collapse Capacity in Steel Moment Resisting Frames

Although the total collapse of buildings under earthquake occurs less but the incidence in recent decades and the possibility of its re-occurrence in the future has made research inevitable in this field. Several numerical and laboratory studies have been carried out on the seismic collapse of the structures. The most common model considering the strength and stiffness deterioration of the structural elements under earthquake is the Ibarra-Madina-Krawinkler three-linear behavioral model that in the case of steel structures, its parameters is presented via performing a large number of laboratory connection tests by the other researchers. The behavioral models resulted from laboratory tests are usually accompanied by a fitting mathematical model with many errors, i.e., the existence of uncertainty in laboratory behavior models is the fundamental challenge of their practical application. In this research, a 5-story steel structure has been designed with intermediate moment resisting frame in accordance with the internal codes. The effect of strength and stiffness deterioration of structural elements is performed based on the Ibara-Madina-Krawinkler behavioral model. Incremental dynamic analysis was carried out under the proposed 50 pairs of earthquake records proposing FEMA P 695 instruction and the fragility curves of its collapse capacities have been developed considering the uncertainty in the yielding moment and the capping moment of the elements and the ultimate rotation capacity of the elements. The results show that among the studied parameters, the uncertainty in the capping moment parameter has the greatest effect on structural collapse capacity and it can change to 19.2% the collapse probability. Uncertainty of the ultimate rotation capacity compared to the other parameters played a small role in structural collapse capacity and has changed the collapse probability up to 5.2 %.