大跨径钢管混凝土拱桥拱肋钢管制造线形的修正方法研究

Study on Correction Method for Fabrication Geometry of Steel Tube for Rib of Long-span CFST Arch Bridge

为了确定大跨径钢管混凝土拱桥拱肋钢管制造线形修正方法,以跨径为507 m的合江长江公路大桥为研究对象,开展了钢管混凝土拱桥拱肋钢管制造线形预拱度设置方法的研究。给出了钢管混凝土拱桥拱肋合理组成部分及各部分钢管预拱度的计算方法,提出了完全分配法的预拱度设置方法。对比了三角形分配法、坐标分配法、二次抛物线分配法、影响线分配法和完全分配法得出的拱肋钢管预拱度制造线形。利用有限元分析软件MIDAS/Civil建立了合江长江大桥的有限元模型,研究了常用的预拱度分配方法和完全分配法对成桥受力状态的影响。引入弯曲应变能作为拱肋无应力线形的评价指标,对比了完全叠加法(竖向)、完全叠加法(三向)、二次抛物线分配方法、无预拱度4种线形下的弯曲应变能。结果表明:各种预拱度分配方法获得的拱肋钢管预拱度制造线形曲线存在较大偏差;对于大跨径钢管混凝土拱桥来说,不同预拱度分配方法对结构应力的影响较小;三向变形的完全叠加法弯曲应变能是最小的。综合内力状态和弯曲应变能来看,对于大跨径钢管混凝土拱桥拱肋钢管制造线形的修正而言,常规的预拱度设置方法已不能够满足大跨径拱桥的受力要求,建议按照完全分配法进行修正。

In order to determine the correction method for fabrication geometry of steel tube for rib of longspan CFST arch bridge,on the study background of Hejiang Yangtze River Highway Bridge with 507 m span,the method for setting the camber in fabrication geometry of steel tube for ribs of CFST arch bridge is studied.The reasonable components of the arch ribs of CFST arch bridge and the calculation method of camber of each part are proposed,and the method for setting camber by complete distribution method is put forward.The rib cambers in fabrication geometry of steel tube obtained by using triangle distribution method,coordinate distribution method,secondary parabola distribution method,influence line distribution method and complete distribution method are compared.The finite element model of Hejiang Yangtze River Bridge is established by using finite element analysis software MIDAS/Civil,and the influences of common camber distribution method and complete distribution method on stress state of finished bridge are studied.By introducing the bending strain energy as the evaluation indicator of stress-free geometry of arch rib,the bending strain energy among 4 types of geometry,which are complete superposition method(vertical),complete superposition method(3-directional),secondary parabola distribution method and no camber,are compared.The result shows that(1)there are large deviations among fabrication geometric curves of rib cambers fabrication geometry of steel tube obtained by various camber distribution methods;(2)for long-span CFST arch bridge,different camber distribution methods have a little influence on structural stress;(3)the bending strain energy of complete superposition method considering 3-directional deformation is the smallest.Comprehensively considering internal force state and bending strain energy,for the correction of fabrication geometry of steel tube for rib of long-span CFST arch bridge,the conventional camber setting method cannot meet the stress requirements of long-span arch bridges.It is suggested to carry out the correction by using the complete distribution method.