A Proposed Method to Satisfy Code Drift Criteria to Achieve Building with Higher Seismic Performance

The first step in designing structures is choosing sufficient elements for the applied loads, including dead, live, wind and earthquake ones. Then, drifts of all stories are compared with allowable values and if required some structural elements are so resized to satisfy the drift criteria. The process of resizing is normally carried out by trial and error and relied mostly on engineering judgment. In other words, there are many approaches for satisfying the drift criteria, which some of them may lead to structures with poor seismicbehavior. Moreover, based on Iranian Standard 2800, the designer is allowed to use analytical period of vibration in drift controlling process, instead on one calculated by the code proposed formula. In this study, a method is proposed to find the best elements for resizing and subsequently satisfying the drift controlling criteria. Furthermore, it is shown that applying the analytical period of vibration leads to structures with better seismic behavior. For the purposes, Endurance Time method is applied in which nonlinear behavior of slender special moment resisting frame steel structures and their damage indices are considered.