双向地震输入下配高强钢筋的框架结构非弹性地震反应

为了研究配置不同高强钢筋的混凝土框架结构的抗震性能，在3个抗震设防烈度区按现行规范分别设计了按等强代换原则配置3种不同高强钢筋的空间框架结构（I组），利用OpenSEES软件对结构进行了多组双向水平地震动输入下的非弹性地震反应分析。并以HRB400钢筋为基础，按等面积代换原则将8、9度区结构的柱纵筋分别替换为HRB500及HRB600钢筋（II组），并完成相应非弹性地震反应分析以考察此做法对结构屈服机制的控制效果。I组结构的分析结果表明：在同一烈度区，随配筋强度的增大，结构的整体和局部位移响应呈小幅增大，而杆端出铰率及转角延性需求都有所下降，结构抗震性能有所提高；8、9度区采用HRB400及HRB500钢筋的结构，在罕遇地震作用下形成以柱铰为主或柱铰偏多的梁柱铰混合耗能机制，其地震反应相对不利，而采用HRB600钢筋之后，柱铰数量明显减少，抗震性能明显改善，但其柱端最大转角及其最大延性需求仍大于梁端，未能充分发挥梁端的良好耗能作用。II组结构的分析结果表明：将柱纵筋按等面积代换原则由HRB400钢筋替换为更高强度钢筋后，柱承载力得到实质性加强，柱铰数量显著减少，梁铰数量增加，结构形成了以梁铰为主或梁铰较多的混合耗能机构，其整体抗震性能明显提高。

Inelastic Seismic Response of Concrete Frame Structures Reinforced with High Strength Steel Bars Under Bi-directional Earthquake Inputs

To study the seismic behavior of concrete frame structures reinforced with different high strength steel bars, spatial concrete frames (Group I) reinforced with three types of rebars but keeping the same moment-strength at every critical section were designed in three seismic intensity zones according to current design codes. Inelastic seismic response analyses of the frames were performed under bi-directional horizontal ground motion inputs with OpenSEES software. Meanwhile, based on the frames reinforced with HRB400 rebars, the longitudinal bars in columns of frames in the Zone 8 and Zone 9 (Group II) were replaced by HRB500 and HRB600 rebars with the same area-ratio, and corresponding seismic response analyses were conducted to investigate the control effects on the structural yielding mechanism. The result of Group I showed: In the same seismic fortification zone, with the growth of the rebar strength, the whole displacements and local displacements of the frames increased slightly, but hinge ratios and rotation ductility demands decreased, which indicating a better seismic performance in frames; The frames in Zone 8 and Zone 9 reinforced with HRB400 and HRB500 rebars demonstrated a column-hinge-dominated energy dissipation mechanism or one with more column hinges than beam hinges under rare-earthquake inputs, which implying an unfavorable seismic response; The counterpart frames reinforced with HRB600 rebar exhibited a notable improvement in seismic performance with significantly reduced column hinges, but maximum rotation and ductility demands of columns were larger than those of beams, which indicating failure in making full use of good energy dissipation of beams. The result of Group II showed: When the longitudinal bars of HRB400 in columns were replaced by higher-strength rebars with the same area-ratio, the moment capacities of columns were enhanced substantially; Column hinges significantly reduced meanwhile beam hinges significantly increased, and the frames formed a beam-hinge-dominated energy dissipation mechanism, which indicating a noticeable improvement in the overall seismic performance of the structures.