Seismic Optimization of Steel Moment Resisting Frame Using Uniform Deformation Algorithm
Subject Areas : Analysis of Structure and Earthquake
Amir hassan
Alizadeh
1
(Faculty of Engineering Civil Engineering Department/Ahar/Iran)
Mehdi
Rahimi Asl
2
(استادیار، گروه عمران، واحد اهر، دانشگاه آزاد اسلامی، اهر، ایران)
Keywords: Optimization, Short steel frame, Uniform deformation algorithm, Life safety performance levels.,
Abstract :
The overall aim of conducting this research is to optimize the medium steel bending frame in the level of life safety risk according to FEMA 350. For this purpose, two 3- and 5- story steel structures have been considered. These structures were designed according to AISC regulations and then subjected to seismic optimization using uniform deformation algorithm. The method of uniform deformations, which is one of the fast methods in optimization based on performance criteria, has been used for optimization so that the dispersion of plastic rotations created in the structural components reaches the lowest value and convinces the permissible plastic rotations at the level of life safety risk based on FEMA regulations. Opensees open-source software based on nonlinear time history method was used for modeling. The aim of optimization is to achieve appropriate performance at the risk level and performance level simultaneously. Also, the improved structure has been subjected to earthquake records with different intensities and its performance has been examined. The results indicate that in the process of using this algorithm, convergence is well-established and the use of the objective function of plastic rotations is considered one of the most suitable methods in the optimization of steel structures. Changes in the distribution of materials from structural components have been made mainly from the upper stories towards the lower stories and from the side members to the inner members of the frame. Also, the optimization in the level of life safety performance reduces the weight of both structures and leads to a reduction in their weight between 9 and 20 percent.
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