A. Azarbakht - Graduate Student of IIEES, Tehran, I.R. Iran
A. S. Moghadam - Assistant. Professor, Head of Seismic Vulnerability and Retrofitting Department of IIEES, Tehran, I.R. Iran,

Incremental Dynamic Analysis (IDA) is a method that offers seismic demand and capacity prediction capability by using a series of nonlinear dynamic analyses under suitably scaled ground motion records. To apply the method, one needs to choose a suitable ground motion Intensity Measure (IM) and a representative Damage Measure (DM). In addition, proper interpolation and summarization techniques for multiple records need to be employed, providing the means for estimating the probability distribution of demand given intensity.Limit-states, such as dynamic global system instability, can be naturally defined in the context of IDA, thus allowing annual rates exceedance to be calculated.A performance-based design method enables designers to evaluate a graduate suit of performance levels for a structure in a given hazard level environment. One component of this framework is a probabilistic seismic demand model. A probabilistic seismic demand model relates ground motion Intensity Measures to structural Demand Measures. It is formulated by statistically analyzing the results of a suit of non-linear time-history analyses of typical structures under expected earthquake in the urban region.To illustrate all the above concepts, the procedure has been applied to study the seismic reliability of a stack that has 76.2-meter height