系杆拱桥吊杆张拉方案对结构受力特性影响分析

Influence Analysis of Tensioning Scheme of Tied Arch Bridge Suspender on Mechanical Characteristics of Structure

系杆拱桥是组合体系中的一种柔性系杆刚性拱。吊杆的安装与张拉是系杆拱桥施工中至关重要的环节,拱肋为主要受压构件。系梁的刚性较一般的梁要小,吊杆的张拉力不同、张拉顺序不同会对系梁体内应力和拱肋内力分布及大小产生不同的影响。为保证系杆拱桥成桥后梁体应力满足规范限值并使拱肋受力合理,探讨了吊杆的最优张拉方案。文中以兰新二线乌鲁木齐河特大桥为工程背景,通过有限元模型和室内模型试验研究了四种工况下对梁体应力及拱肋受力特性的影响。研究发现:在不同张拉顺序及张拉力下,梁体和拱肋受力并不能同时达到最优,就一种工况而言,在梁体应力合理的同时拱肋就会出现受力不理想的情况;同样,当拱肋安全储备较大时梁体应力就会出现超出规范限制的现象。在具体施工时应综合考虑拱肋、梁体及索力分布情况,并结合现场和施工难度选择相应的施工方案。

Tied arch bridge is a kind of composite system arch bridge with flexible hanger rigid arch. The installation and tensioning is crucial to the construction of tied arch bridge, andthe arch rib is the main compression member. The stiffness of the beam is smaller than the ordinary beam. Internal stress of tied beam and internal force distribution of arch rib is different under different tension and tension sequence of hanger.In order to ensure that the beam stress can meet the specification limits and the stress of arch rib is reasonable after completion of the tied arch bridge,the optimal tensioning scheme of the boom is discussed. This paper takes the Urumqi River Bridge on the second route of Lanxin as the engineering background,and based on finite element model and laboratory model test studies the effects of four kinds of working conditions on the stress characteristics of the beam and arch rib. The study finds that the beam body and arch rib can not reach the optimum at the same time under different tension sequence and tension. Under a construction condition, when the stress of the beam is reasonable,the arch rib will appear to be not ideal. Similarly,when the arch rib safety margin is relatively large, the stress of the beam will appear beyond the standard limit.Arch rib,beam body and hanger cable force distribution should be fully considered in the specific construction process. In addition,the construction sequences and tension should be selected according to the situation and the difficulty of construction.