Method of seismic reliability evaluation for moment-resisting steel frames

A method for the evaluation of structural performance of moment resisting steel frames in future earthquakes is developed in this study. With this approach, one can evaluate the probability of failure (exceedance of a limit state) of such frames during their design lifetime.A seismic hazard analysis is carried out in which the characteristics of ground motion at a site are identified and the uncertainties associated with source and ground motion parameters are quantified. Earthquake excitation is modeled by a nonstationary random process with time-varying amplitude and frequency content. The parameters of the model are identified from available seismological and geological information at the site where the structure is located.A strong-column-weak-beam model is proposed in this study for moment resisting steel frames which reduces the number of degrees of freedom in the analysis and produces the response of these frames with computational efficiency and good accuracy. A random vibration analysis is performed based on the equivalent linearization method and the response statistics are evaluated for a given set of ground motion parameters. The conditional probability of failure of the frame is then derived using these statistics. A fast integration technique based on the first order reliability method is finally used to evaluate the probability of failure during the design lifetime of the structure.The robustness of the proposed method is demonstrated in the numerical examples throughout this study. The method can be used in assessing the risk implied in current earthquake resistant design practice, and in developing reliability-based code procedures.U of I OnlyETDs are only available to UIUC Users without author permissio