Seismic Optimization of Steel Moment Resisting Frame Using Uniform Deformation Algorithm
Amir hassan Alizadeh
1
(
Faculty of Engineering Civil Engineering Department/Ahar/Iran
)
mehdi rahimiasl
2
(
Faculty of Engineering Civil engineering Department/ahar/iran
)
Keywords: Optimization, Short steel frame, Uniform deformation algorithm, Life safety performance levels,
Abstract :
In this research, aim is to optimize the steel bending frame in the level of life safety according to FEMA 350. For this purpose, two steel structures with the number of 3 and 5 floors have been considered. These structures were designed according to AISC regulations and then subjected to seismic optimization using uniform deformation algorithm. This method has been used in this research for optimization so that the dispersion of plastic rotations created in all components of the structure reaches the lowest value and convinces the permissible plastic rotations at the level of LS based on FEMA regulations. Opensees software based on nonlinear time history method was used for modeling. The goal of optimization is to achieve appropriate performance at the level of risk and level of performance at the same time. Also, the improved structure has been subjected to earthquake records with different intensities and its performance has been examined. The results show that convergence is well established in the process of using this algorithm, 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 to the lower stories and from the side members to the inner members of the frame. Also, the process of improvement in the L.S performance reduces the weight of both structures and leads to their weight reduction between 9% and 20%.