Behavioralcoefficient evaluation of cold-rolled steel balloon frames under earthquake loads

Commoncold- rolled steel frames, constructed in a panel, have a behavior factor of 4 and their heights are limited to 20 m, according to IBC2009. The main objective of this paper is to investigate the behavioral coefficient of cold rolled steel frame, which are constructed with the balloon method (continuous studin height).Studs are fabricated by C-shapedcross sections and boxes of cold-rolled and lateral members are made by cold-rolled box sections. In order to seismic behavior evaluation, the bending moment–rotation diagrams associated with C-sections and box shapes are first determined by laboratory observations and Finite Element analysis of nonlinear buckling Method using ABAQUS. Then, the results have been compared to the nonlinear pushoveranalysis frames in SAP2000. Analytical frames have thesame span and the numbers of X braces are determined based on initial design criteria, in accordance with IBC and AISI. Nonlinear pushover analyses are conducted over one to five-story frames. The bending moment-rotation diagrams of cold-rolled sections have been obtained, and the results show the average behavioral factor of steel frames under analyses, by a substantial increase, reach to around 6, indicating an improvement in behavioral factor of the balloon system compared to the traditional panel.