عنوان مقاله [English]
Reliability theory, which itself is a part of general probabilistic concepts, plays a basic role in the design provisions of structures. In limit state or performance-based design, the structural reliability theory plays an essential role in setting the design criteria, as well as demonstrating the target reliability level appropriate to each society. Structural reliability is necessary for having a model that makes it possible to perform rational calculations in the presence of uncertainties in the various parameters encountered in loading parameters and those of structures such as material property, geometric dimensions and the nonlinear dynamic analysis procedure. Although several procedures for structural reliability evaluation, treating non-linear displacement responses, have been proposed, they require complex procedures that may not be used in the practical design process. In the present study, a ductility-based procedure is proposed to maintain both accuracy and simplicity, based on non-linear dynamic response analysis. The use of results of the nonlinear dynamic analysis for a few records to establish the seismic demand curve could be considered the computationally intensive part of the incremental dynamic analysis (IDA). The IDA is an emerging structural analysis method that offers thorough seismic demand and limit-state capacity prediction capability by using a series of nonlinear dynamic analyses under a suite of multiply scaled ground motion records. We used probabilistic tools, by applying the total probability theorem, in order to derive the hazard values for the ductility-based response. This study presents an analytical foundation for probability-based formats for seismic design and assessment of structures. In this study, a reliability assessment of six steel moment resisting frames (MRF), designed according to Iranian codes, is carried out. The reliability indices of these designed steel MRF structures are to be estimated using the present procedure, the ductility-based procedure.