混合梁斜拉桥混凝土–钢桁结合段模型试验

Model Test of Concrete-steel Truss Joint Section of Hybrid Cable-stayed Bridge

鸭池河大桥是国内首次采用钢桁梁的大跨度混合梁公路斜拉桥,目前有关混凝土-钢桁混合梁结合段的研究极少,结合段构造设计基本参照普通钢-混凝土结合段的构造原理,为验证其混凝土-钢桁结合段截面形式和构造设计的合理性,有必要对混凝土-钢桁结合段的力学性能、刚度匹配和变形特点进行详细研究。本文开展了几何缩尺比为1∶5的结合段模型试验,分别考察在体内预应力加载、设计极限荷载和1.6倍设计极限荷载作用下结合段各部分的应力分布和变形情况。结果显示,该桥主梁混凝土-钢桁结合段两端刚度过渡顺利,具有足够的承载力和安全储备,整个试验过程中混凝土-钢桁结合段表现出了良好的力学行为特点,表明这种新型混凝土-钢桁结合段的构造设计合理,可应用于同种类型桥梁的设计。

The Yachihe highway bridge is a hybrid cable-stayed bridge in which concrete-steel truss joint section is first adopted in China.However,the research concerning the bridge type is far from enough.The structure design of joint section is roughly based on the structural principle of ordinary steel-concrete joint section.In order to verify the rationality of the section type and the structure design used in the concrete-steel truss joint,some detailed research are carried out including mechanical performance of joint section,stiffness matching and deformation characteristics of concrete and steel truss beam.In the research a static model test in scale of 1 ∶ 5 is designed and conducted,the model test is used to investigate the stress distribution and deformation characteristics of the concrete-steel truss joint under different loading condition,such as internal prestress state,design ultimate load state and 1.6 times design ultimate load state.The results show that the concrete-steel truss joint section achieves an smoothly transition of stiffness,it has sufficient bearing capacity and safety margin.The concrete-steel truss joint shows good mechanical behavior during the entire test.The research indicates that the structure design of the concrete-steel truss joint is reasonable,and this structure can be used in similar bridge's design.