单拱肋下承式连续梁拱组合桥梁拱协作机理

Beam-arch Cooperation Mechanism of Single-arch through Continuous Beam-arch Combination Bridge

以单拱肋下承式连续梁拱组合桥西宁祥瑞街大桥为工程背景,基于吊杆力相等假定和膜张力假定,采用结构力学的方法,推导出梁拱组合体系在均布荷载作用下,拱肋分担荷载比、拱梁弯矩比、拱梁变形比表达式,以此揭示梁拱协作机理。采用四次抛物线对吊杆力进行拟合,通过对公式、有限元计算结果进行误差分析,得出吊杆力修正系数,以此减小吊杆力相等假定带来的误差。同理,采用余弦荷载对吊杆力进行拟合,通过对吊杆力公式、膜张力公式计算结果进行误差分析,得出膜张力修正系数,以此减小膜张力假定带来的误差。最终结合吊杆力修正系数和膜张力修正系数,计算出主梁跨中挠度、拱肋跨中挠度以及吊杆力分担外荷载比例的修正系数分别为1.1、1.2、0.9,以此减小公式误差。

Taking Xiangrui Street Bridge in Xining as the engineering background,which is a single-arch through continuous beam-arch combination bridge,based on the assumption of equal suspender force and filmy force,the method of structural mechanics is used to deduce the expression of the load sharing ratio of arch,the bending moment ratio of arch-beam and the deformation ratio of arch-beam,reveal the mechanism of beam-arch collaboration bridge under uniform load.The quartic parabolic curve is used to fit the suspender force.The error analysis of the formula and the finite element calculation result are carried out to determine the suspender force correction coefficient,so as to reduce the error caused by the assumption of equal suspender force.In the similar way,the cosine curve is used to fit the suspender force.The error analysis of the suspender force formula and the filmy force formula calculation results are determined from the filmy force correction coefficient,so as to reduce the error caused by the assumption of filmy force.Through the suspender force correction coefficient and the filmy force correction coefficient,the correction coefficients of the beam deflection,arch deflection and the proportion of external load sharing by the suspender force are finally calculated to be 1.1,1.2,and 0.9 respectively,in order to reduce the formula error.