钢管混凝土拱桥拱铰斜腹杆合理夹角分析

Reasonable Angle of Arch Hinge Diagonal Web Member of Concrete Filled Steel Tubular Arch Bridge

钢管混凝土拱桥钢管拱通常采用缆索吊装悬臂拼装法施工,为便于调整拱肋安装线形,多在拱脚处设置临时拱铰。将拱铰结构分别简化为理想桁架和刚架结构,根据力系平衡原理推导出理想桁架的斜腹杆轴向力一致表达式,将欧拉临界荷载与轴向力之比定义为腹杆的稳定系数,建立起稳定系数与腹杆夹角的关系,得到了腹杆最大稳定系数对应的夹角值;运用力法原理,推导了三角刚架端弯矩和轴向力计算表达式,通过算例验证了计算公式的正确性,在此基础上进一步研究了拱铰刚架内力与斜腹杆夹角的变化规律。结合JTG/T-D65-06—2015《公路钢管混凝土拱桥设计规范》对主、支管夹角不宜小于30°的构造要求,得到拱铰斜腹杆夹角在60°~100°间较为合理结论,验证了国内部分已建钢管混凝土拱桥拱铰构造设计的合理性。

The steel tubular arch segments of concrete filled steel tubular(CFST)arch bridge were usually constructed by cantilevering assembly method with cable hoisting.In order to adjust the installation alignments of arch rib,temporary arch hinge was often set at the springing.The arch hinge structures were simplified as the ideal truss and the rigid frame structure respectively.Firstly,according to the balance principle of force system,the consistent expression of the axial force of the diagonal web member of the ideal truss was derived.The ratio of the Euler critical load to the axial force was defined as the stability coefficient of the web member,the relationship between the stability coefficient and the angle between the web member was established,and the angle value corresponding to the maximum stability coefficient of the web member was obtained.Secondly,based on the principle of force method,the calculation expressions of moment and axial force at the end of triangular rigid frame were derived.The correctness of the calculation formula was verified by a calculation example.On this basis,the change law of the angle between the internal force of arch hinged rigid frame and diagonal web member was further studied.According to the structural requirements of the code for design of highway concrete filled steel tubular arch bridge that the angle between the main and branch pipes should not be less than 30°,it is concluded that the angle between the diagonal web members of arch hinge is more reasonable between 60°and 100°,which verifies the rationality of the arch hinge structural design of some built CFST arch bridges in China.