Nonlinear dynamic response of frame structures reinforced with high strength steel bars under strong earthquake action

Five frame structures located in intensity region 8(0.3 g) were designed and analyzed under bi-directional earthquake waves by Perform-3D program. Four frames were reinforced with 500 MPa and 600 MPa grades steel bars respectively based on the one reinforced with 335 MPa grade steel bars in accordance with the 'substitution by equal strength' principle and codes of China. The nonlinear earthquake response analysis results demonstrate that: compared with the frames reinforced with normal strength steel bars, although the maximum top displacement and story drift have a limited increase in the frames reinforced with high strength steel bars, they are still less than the code limits. It is indicated that frames with high strength steel bars also have a good overall seismic performance. The analysis results also show that: if taking the displacement ductility factors as an indicator to measure the ductility of specimens, the factors of those reinforced with high strength steel bars are smaller than frames reinforced with normal strength steel bars, while when taking the ultimate drift angle as an indicator, the drift angle limit increases with the increasing of the strength of steel bars.