Effects of different lateral load patterns on the ductility ratio of steel structures

The ductility ratio and reduction factor due to ductility of intermediate steel moment resisting frames are evaluated based on nonlinear static analyses (pushover analyses). For this purpose, three-, six-, nine-, and twelve-story steel frame structures, considered as low-, medium-, and high-rise frame structures, were designed according to AISC provision. Nonlinear static analyses using lateral load patterns corresponds to uniform and first mode shape were carry out to compute ductility ratio and reduction factor due to ductility of mentioned structures with consideration of failure criteria at both member and structural level. The results obtained by nonlinear static pushover with two mentioned lateral load patterns are compared. According to the analysis results, it is observed that the ductility ratio and reduction factor due to ductility corresponds to first mode shape lateral loads are a bit higher than those obtained from uniform lateral load pattern. It is also concluded that the ductility ratio and the reduction factor due to ductility of structures are decreased with increasing the height of the structures. This result shows that the value of ductility ratio and reduction factor due to ductility depends, among other parameters, on the height of a structure.