Optimum Seismic Design of Short to Mid-Rise Steel Moment Resisting Frames Based on Uniform Deformation Theory

In current work, an effective method is introduced for the optimal cross-section distribution in steel moment resisting frames under severe earthquakes by means of uniform deformation theory and adaptive method. The main goal is to distribute the construction material (weight) along the height of the structure in such a way that the lowest damage due to earthquakes is obtained. In adaptive method, materials gradually transfer from strong parts to weak parts by an iteration procedure during nonlinear time history analysis. In order to demonstrate the effectiveness of the proposed method, the optimal distribution of the cross-sections is obtained for ۵ and ۱۰ story steel moment resisting frames. In order to reduce the sensitivity of the optimal response to discrete cross-sections, continuous cross-sections fitted between DIN-Standard cross-sections have been used in order to achieve its optimal state. The steel moment resisting frames are optimized under five natural earthquakes. Results indicate that the optimal frames designed by this method show not only a more uniform deformation under earthquakes, but also less weight in comparison to the original structure designed according to the ASCE۰۷-۱۰ code. The reduction in structural weight reaches ۴۰% in some cases leading to significant reduction in frame construction costs.