剪跨比对高强钢筋混凝土桥墩抗震性能影响的试验研究

Research on the Effect of Shear Span Ratio on Seismic Behavior of High Strength Reinforced Concrete Bridge Piers

设计4个配置HRB500高强钢筋的混凝土桥墩构件并进行拟静力试验,分析剪跨比、轴压比、箍筋间距对桥墩抗震性能的影响,研究高强钢筋混凝土桥墩的破坏特征、承载能力、变形能力、延性性能、滞回特性和耗能能力等抗震性能指标。结果表明:剪跨比较大的高强钢筋混凝土桥墩呈现弯曲破坏形态,滞回曲线更为饱满,刚度退化更缓慢,耗能能力更强;剪跨比较小的构件呈现剪切破坏形态,具有较高的承载能力;剪跨比较大的高强钢筋混凝土桥墩的破坏位移是较小剪跨比构件的3.3倍,具有较强的变形能力,但极限荷载仅是后者的0.5倍;当加密剪跨比较大桥墩的箍筋后,延性系数提升了12.4%,表明减小箍筋间距可以改善构件延性;增大小剪跨比桥墩的轴压比使构件的承载力提高21%,但破坏位移降低9.8%,对耗能和刚度退化影响不大。

In this study, four HRB500 high strength reinforced concrete bridge piers are designed and subjected to reversed cyclic loading. The effect of shear span ratio, axial compression ratio and stirrup spacing on seismic performance of bridge piers are studied. The failure characteristics, bearing capacity, deformation capacity, ductility, hysteresis property and energy dissipation of high strength reinforced concrete bridge piers are compared. The results show that the high strength reinforced concrete bridge piers with large shear span exhibit bending failure mode, fuller hysteresis curve, slower stiffness degradation and stronger energy dissipation capacity. The specimens with relatively smaller shear span show shear failure mode and have higher bearing capacity. The failure displacement of reinforced concrete piers with larger shear span ratio is 3.3 times of that with smaller shear span ratio, and the piers have larger deformation capacity, but the ultimate load is 0.5 times. When the added stirrup spacing of specimen with larger shear span ratio, the ductility is increased by 12.4%, indicating that reducing the stirrup spacing could improve the ductility. When the axial compression ratio of the piers with smaller shear span ratio is increased, the bearing capacity of the piers is further increased by 21%, but the failure displacement is reduced by 9.8%, which has minor effect on the energy dissipation and stiffness degradation.