简支转连续钢-混组合梁桥负弯矩区设计及工程应用

Design and engineering application of negative moment zone of simply supported to continuous steel⁃concrete composite beam bridge

以国内某座简支转连续钢-混组合梁桥为依托,提出了一种简支转连续结构负弯矩区构造设计方案。采用有限元分析和实桥试验相结合的方法,对简支转连续钢-混组合梁桥负弯矩区的受力性能进行分析,验证了该构造设计的可行性,最后就负弯矩区改善开裂的措施进行了探讨。研究结果表明,对于钢-混组合连续梁桥,简支转连续的施工方法与焊接连续施工方法相比,可减小墩顶负弯矩;承载能力极限状态时,负弯矩区混凝土最大裂缝宽度满足规范要求;桥面板钢筋直径以及混凝土自身力学特性是影响负弯矩区开裂的关键因素,适当加大桥面板钢筋直径、采用超高性能混凝土可以有效减小简支转连续钢-混组合梁桥负弯矩区混凝土的开裂;顶升支座法可以在一定程度上减小墩顶负弯矩,对控制开裂有利。

Based on one simply supported to continuous steel⁃concrete composite bridge in China,a structural design scheme of simply supported to continuous negative moment zone was proposed.By means of finite element analysis and real bridge test,the mechanical performance of the negative moment zone of the simply supported to continuous steel⁃concrete composite beam bridge was analyzed,the feasibility of the structural design was verified,and the measures to improve the cracking in the negative moment zone were discussed.The results show that for steel⁃concrete composite continuous beam bridge,the construction method of simply supported to continuous can reduce the negative bending moment of pier top compared with the welded continuous construction method.In the limit state of bearing capacity,the maximum crack width of concrete in the negative bending zone meets the specification requirements.The diameter of steel bar and the mechanical characteristics of concrete are the key factors affecting the cracking of the negative moment zone of the bridge panel.Appropriately increasing the diameter of steel bar of the bridge panel and using ultra⁃high performance concrete can effectively reduce the cracking of the concrete in the negative moment zone of the simple supported to continuous steel⁃concrete composite beam bridge.The jacking support method can reduce the negative bending moment of pier top to a certain extent,which is beneficial to control cracking.