The application of endurance time method for optimum seismic design of steel moment-resisting frames using the uniform deformation theory

The optimum seismic design of structures is one of the biggest issues for engineers to build resistant and economic structures. In this research, the application of the endurance time method in optimum performance design of steel moment-resisting frames using the uniform deformation method is evaluated. First, three steel moment-resisting frames with 3, 7 and 12 stories are considered. After that, the structures are optimized by endurance time method analysis and the uniform deformation theory, under a series of acceleration functions. Also, results are compared with the results of time history analysis based on earthquakes. The results revealed that endurance time method and time history analysis of earthquakes at low and moderate seismic hazard levels are well matched, while this adjustment does not exist for high seismic hazard level. In addition, the optimum structure at one hazard level does not lead to optimum structure in other hazard levels. To have the best performance at different hazard levels, the frames should be optimized at the moderate seismic hazard level. In order to optimize the structure at all seismic hazard levels, the GAP dampers can be used. These dampers should be effective after a specified drift at the lower seismic hazard level. In addition, the best values for convergence power of the uniform deformation method are between 0.05 to 0.15 for this purpose. By using such dampers, it is possible to have uniform drift distribution at different seismic hazard levels.