EFFECT OF STRUCTURAL MODELING UNCERTAINTIES ON SEISMIC PERFORMANCE OF STEEL MOMENT RESISTING FRAMES

Prediction of structure’s response to seismic loads is a complex problem with many parameters involved that some of them can behave highly uncertain. Nonetheless it is needed to have a clear understanding of how these uncertainties affect structural seismic performance. In this matter, it is convenient to separate uncertainties into two categories: aleatory (due to variability of strong ground motions) and epistemic (related to structureʹs numerical model). This Paper aims to investigate effect of structural uncertainties on seismic performance of steel moment resisting frames through extended IDA of a sample 5-storey frame. In this regards, uncertainties in damping, mass, yield strength and ultimate strength of structural steel have been considered as probabilistic variables. Latin Hypercube Sampling (LHS) has been used to create random realizations of structures. With the aid of reliability methods, different sources of uncertainty and their ranges of influence on seismic performance have been disaggregated Considering results, it can be seen that uncertainties in selected parameters have important effect on seismic performance. Capacity and demand estimations based only on deterministic procedures may ignore some substantial points. Also including these uncertainties in performance calculations can considerably change probability of achieving desired performance at some levels.