钢管混凝土组合桥墩抗震延性的定量计算

A quantitative calculation of seismic ductility of concrete-filled steel tube composite piers

为利用截面设计参数定量计算钢管混凝土组合桥墩抗震延性,选择矩形桥墩作为研究对象,鉴于我国桥墩服役期工作轴压比一般处在0.1~0.4的现状,选择此区间作为研究范围,根据平截面假定、力的平衡和材料本构关系,分别建立了截面屈服曲率和极限曲率关于截面设计参数的解析公式,并通过数值方法验证了解析公式的正确性。将截面极限曲率与屈服曲率之比即曲率延性系数作为评价指标,最终建立评价指标关于截面设计参数的解析公式。研究结果表明：利用推导的解析公式可以实现对钢管混凝土组合桥墩曲率延性系数的定量计算,结果可信;通过曲率延性系数的比较,证明在耗材相同的情况下,钢管混凝土组合桥墩比箍筋约束混凝土桥墩具有更好的抗震延性。

This paper researches rectangular piers to quantitatively evaluate the seismic ductility of concrete-filled steel tube composite piers for various cross-section design parameters. Because the axial load ratio of most piers was in the range 0.1- 0.4 during the service period, this range of axial load ratios was chosen for the research. Using the flat-section assumption and the force balance and material constitutive relations, the yield curvature and limit curva- ture of the section were obtained analytically from the design parameters. The analytic results for the yield curvature and ultimate curvature were verified by a numerical method. The ratio of limit curvature to yield curvature was defined as a curvature ductility factor that was treated as an evaluation index that allowed the factor to be calculated when the cross-section design parameters were known. The results show that the analytical formula for the curvature ductility factor is feasible and credible. By comparing curvature ductility factors, the conclusion is reached that, for the same assumptions, concrete-filled steel tube composite piers have better seismic ductility than confined concrete piers with stirrups.