Evaluation of Displacement Amplification Factor of Steel Special Moment Frames Using Incremental Dynamic Analysis

In recent decades several destructive earthquakes resulted in extensive structural and non-structural damage in structures, that which was produced by lateral displacements. So, it reveals the necessity for theof accurate estimation of the lateral displacement of the structures in the design procedure. According to the present seismic design provisions, displacement amplification factor, (Cd), is being applied to acquire elastic lateral displacements in order to assess inelastic displacements, due to the ground motions. Besides, in many codes, these factors are empirical in nature and is based on structural performance, which has been observed in the past earthquakes; AlsoOn the other hand, the effect of height and number of stories are is neglected. In this paper, the effect of Cd on seismic performance of steel special moment frames is evaluated. Six types of buildings are designed with different values of Cd (i.e., 4, 5, 5.5, 6, 7, and 8). For each type of building,s 5 heights (i.e., 5-, 10-, 15-, 20- and 25-stories) are considered. The numerical finite element models are developed in Opensees. Incremental dynamic and nonlinear static analyses are performed to quantify structures’ seismic performance utilizing fragility curves and FEMA P695 methodology. The results indicate that the values of Cd provided in the codes for steel special moment frames does not induceare not completely effective on seismic performance, especially in short-rise buildings. Also, the probability of collapse of high-rise buildings are is less likely with respect to the medium-rise buildings; Therefore, in high-rise buildings, increasing the amount of Cd is not necessarily recommended, as because it increases the cross sections in of the frame members and makes the design uneconomical.