高轴压比下内置闭合钢管的钢骨砼桥墩曲率延性系数

Curvature ductility factor of steel reinforced concrete piers with closed steel tubes under high axial load ratio

为提高震区桥梁抗震延性,选择内置闭合钢管的钢骨混凝土矩形桥墩进行延性设计.考虑到近场罕遇地震下桥墩可能承受较大轴力,根据平截面假定、力的平衡和材料本构关系,分别推导了高轴压比下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.将截面极限曲率和屈服曲率之比定义为曲率延性系数,实现已知截面设计参数定量计算桥墩延性的目的,并以曲率延性系数为指标比较了钢骨混凝土桥墩和箍筋约束混凝土桥墩的抗震延性.研究结果表明:高轴压比下,利用截面设计参数计算曲率延性系数的解析方法是可行的;当耗材相同时,高轴压比下钢骨混凝土桥墩较箍筋约束混凝土桥墩具有更好的抗震延性.

To improve the seismic ductility of bridges in earthquake regions,rectangular steel reinforced concrete（ SRC） piers with closed steel tubes were selected for ductility design. Because near field piers under severe earthquake may bear large axial force,the analytic formulae of the yield curvature and limit curvature of the section as for design parameters under the high axial load ratio were deduced according to the flat section assumption,force balance and material constitutive relationship. Also,the analytic formulae were verified by the numerical method. The ratio of the limit curvature to the yield curvature was defined as the curvature ductility factor,which can be calculated when the cross section design parameters were known. According to the curvature ductility factor,the seismic ductility of the SRC piers was compared with that of the confined concrete piers with stirrups. The results showthat the analytic method by computing the curvature ductility factor according to the design parameters under the high axial load ratio is feasible. The seismic ductility of the steel reinforced concrete piers is better than that of the confined concrete piers with stirrups under the high axial load ratio with the same consumables.