Document Type : Research Article
Authors
1
Assistant Professor, Civil Engineering Department, Faculty of Engineering, Urmia Branch, Islamic Azad University, Urmia, Iran
2
PhD student, civil engineering, Islamic Azad University, Urmia branch, Urmia
Abstract
Throughout history, structural engineers have always been trying to design optimal structures that are always cheap due to limited resources, and at the same time meet all existing design limitations. After the great damages caused by the earthquakes in the 1990s in America and Japan, the seismic design regulations made significant changes. During the last few years, performance-based design has been introduced in regulations and expanded significantly, on the other hand, the improvement of the computing power of computers and hardware systems has made it possible for people to use optimization methods and Use advanced nonlinear analysis.Therefore, today we can use a meta-heuristic algorithm to find the best design and perform a dynamic analysis to find the response of the structure to design new structures. Although there were not many casualties in these earthquakes, huge economic losses were left, which clearly revealed that the goal of life safety should not be Only the design criteria should be used and more performance levels should be controlled and verified in the designs. The aim of this research is to evaluate the seismic safety of steel frames with optimized cross convergent bracing in the framework of performance-based design approach. This research consists of two main steps. In the first step, two three-span ten-story frames with a cross bracing system with the position of the bracing in the middle opening and the side openings, using the meta-heuristic algorithm of the center of mass in the framework of the performance-based design method, and considering the weight of the structure as the objective function and the external penalty function method have been optimized. In this phase of the study, OpenSees software was used to perform nonlinear modeling and analysis, and MATLAB software was used to implement the optimization problem. In the second step, the seismic safety of the frames resulting from the optimization process has been investigated using incremental dynamic analysis. According to the obtained results, it was observed that placing the brace in the side openings reduces the seismic safety by almost 10% compared to the bracing frames with the placement of the brace in the middle opening.
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