The Effect of Analysis Methods on the Response of Steel Dual-System Frame Buildings for Seismic Retrofitting

In the present paper, the focus is on the evaluation of steel dual-system frame buildings using four main types of structural analysis (Linear Static, Linear Dynamic, Nonlinear Static and Nonlinear Dynamic Analyses) with regard to "Seismic Rehabilitation Code for Existing Buildings in Iran" (based on FEMA 273 and 356) where the first two authors of the article tend to follow the previous work (Section 2). The difference of the results taken from these four types of analyses and also seismic performance of the dual-system buildings will be studied in both linear and nonlinear treatments. Three 2D models which include 3 common dual-system buildings (5,10 and 15-story) have been chosen and designed subjected to earthquake based on the Standard No. 2800 of Iran (3rd revision). Then, the 2D models have been analyzed and controlled according to “Seismic Rehabilitation Code for Existing Buildings”. The selected rehabilitation goal for this research is Fair (Controlling Life Safety and Collapse Prevention in two hazard levels derived from PSHA analysis). Based on the research results, the main role of lateral load-bearing is on bracing members. The linear analysis of bracing members evaluation, has a low accuracy, in evaluation of columns the results derived from linear static analysis shows more accuracy than linear dynamic and nonlinear static analyses. Also, the accuracy of nonlinear static analysis decreases when the number of stories increases.