大跨简支铁路钢管混凝土拱桥徐变效应研究

Creep Effect of Long Span Simply Supported CFST Railway Arch Bridge

为研究大跨简支铁路钢管混凝土拱桥的徐变效应,文中以某哑铃形钢管混凝土拱桥为实例,通过刚度折减法和徐变公式法分别考虑拱肋和系梁的徐变,利用有限元软件建立了三维计算模型,开展了徐变对简支钢管混凝土拱桥的长期变形和内力的影响分析。研究结果表明:拱肋徐变会导致简支钢管混凝土拱桥的拱肋和系梁产生下挠变形,系梁徐变会引起拱肋、系梁上拱;徐变引起的拱肋弯矩变化较大、而轴力变化较小;在大跨度钢管混凝土拱桥的工程实践中,要充分考虑徐变效应的影响,以便能合理预测运营阶段长期时变行为。

The paper studies the creep effect of long span simply supported railway concrete filled steel tubular(CFST)arch bridges.A CFST arch bridge with dumbbell shaped section rib is taken as the practical example.The creep of the arch rib and the tie beam are discussed respectively by the stiffness reduction method and the creep formula method and a three dimensional calculation model is established with the finite element software.Then the effects of creep on the long term deformation and internal force of simply supported CFST arch bridge are analyzed.The results show that the creep of arch rib leads to a downward deformation of the arch rib and the tie beam of the simply supported CFST arch bridge,and that the creep of tied beam causes their upward deformation.Creep causes a larger change in the bending moment of arch rib but a smaller change in the axial force.In the engineering practice of long span CFST arch bridges,the creep effect should be fully considered so that a reasonable prediction can be made of the long term time varying behavior in the operation period.