高轴压比下密置焊接环式高强复合箍筋约束高强混凝土柱恢复力模型研究

Study on restoring force model for high strength concrete columns confined by butt-welded closed composite high strength stirrups with high axial compression ratios

通过对不同轴压比、体积配箍率和箍筋形式的9个焊接环式高强复合箍筋约束高强混凝土柱的1/2模型试件和1个对比试件的抗震性能试验研究,分析了轴压比、配箍率、箍筋形式等因素对试件滞回曲线、骨架曲线、刚度、强度及延性等的影响,并建立了试件的弹塑性恢复力模型。试验结果表明:随着高轴压比的提高,其耗能性能降低,骨架曲线的下降段较陡;随着配箍率的减小,其耗能性能降低,骨架曲线下降段的斜率变大;对照对比试件,焊接环式复合高强箍筋比普通复合高强箍筋的约束效果好,且耗能大,延性性能好。建议的骨架曲线恢复力模型与试验骨架曲线吻合较好,可为高轴压比下由焊接环式高强复合箍筋约束高强混凝土柱组成的框架结构的弹塑性反应分析提供参考依据。

Based on the study on the seismic behavior of nine high strength concrete columns confined by butt-wel- ded closed composite high strength stirrups and one comparison specimen, the influence of axial compression ratios, transverse reinforcement volume ratios and arrangement of confinement reinforcement on hysteretic curves, skeleton curves, rigidity, bearing capacity and ductility of specimens were analyzed, and the restoring force model of them were established. The test results show that： with high axial compression ratios increasing, the energy dissipation capacity decreases, and the descending parts of the hysteresis loops are steeper; with the decrease in stirrup ratio, the energy dissipation capacity decreases, and the slopes of the descending parts of the hysteresis loops are in- creased. Compared with comparison specimen, the confinement, the energy dissipation, and the ductility of high strength concrete columns confined by butt-welded closed composite high strength stirrups are better. The skeleton curves of the proposed restoring force model are already verified by the test and this provides some reference for e- lastic-plastic seismic response analysis of frame structure composed by the high strength concrete columns confined by butt-welded closed composite high strength stirrups with high axial compression ratios.