Lateral Load Distribution based on the Ductility Demand Ratio in Seismic Design of Structures

Abstract

Background/Objectives: In this research, a method is proposed for the design of earthquake-resisting systems in which the distribution of lateral loads is adjusted based on the uniform distribution of seismic demand ratio in load-bearing members of the structure so as to optimally utilize the structure's seismic capacity. To this end, a 4-story building and a 7-story building were used. First, the aforementioned buildings were designed for gravity loads and were analyzed subsequently using the nonlinear analysis method based on the accelerograms of several earthquakes. Methods/Statistical analysis: One of the seismic design methods is the Force-Based Design (FBD) method, which forms the basis of many codes. In this method, the strength parameter is used as the design criterion while it is also necessary to use structural deformations as a design criterion. In current design methods, similar structural members are usually designed to have equal ductility capacities. However, in practice, only a few structural members use the ductility capacity and enter the plastic range under earthquake conditions. Findings: The seismic design of the mentioned buildings was carried out based on the new distribution and their seismic behavior was determined through a nonlinear dynamic analysis with the same ground motions. Applications/Improvements: An improvement in the seismic behavior of beams and columns. In the new structures, a more uniform distribution of ductility ratios along the structure's height is obtained.