Application of Lower Grade Steel on Dynamic Behavior of X-braces in Shear Part 2: Advanced Nonlinear Static and Incremental Dynamic Analyses (IDA)

Document Type : Research Article


1 Department of Civil Engineering, Shahr-e-Qods Branch, Islamic Azad University, Tehran - Iran

2 M.Sc. in Earthquake Engineering, Tehran, Iran


In the first part of this paper, the theory of design of X-braces using different steel grades was introduced and its effects on different frames verified using nonlinear static analyses. It was found that using lower grade steel in X-braces increases the stiffness, energy absorption capacity, damping, and ductility of the system and decreases its lateral drift. To completely investigate the behavior of steel structures with X-bracing systems in design with different steel grades and consider their dynamic behavior, the frames with different stories studied using advanced nonlinear static and Incremental Dynamic Analyses (IDA). The results are presented as comparative diagrams and tables. The near and far-field earthquakes used for dynamic analysis of sand and their seismic performance were studied. Therefore, this research can lead to a better investigation of the seismic behavior of X-braced systems in design with different steel grades. The proposed theory along with analyses shows that building codes and steel seismic design specifications can consider the effects of steel grades in seismic parameters definition of structures. The comparative diagrams and tables show that the seismic behavior of X-braces designed with lower-grade steel improves considerably. Also, the response of structures under near field earthquakes is bigger than related parameters under far-field earthquakes. Also, with an increase in height of the frames and governing bending behavior (relative to shear behavior) and more effects of columns in lateral deflection of frames, the effects of lower-grade steel in the overall behavior of taller buildings decreases gradually.


Main Subjects

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