高墩大跨简支梁桥的特殊梁轨纵向力及其影响

为探讨主梁收缩与徐变和桥墩梯度温度荷载在高墩大跨简支梁桥中产生的特殊梁轨纵向力,以10跨64 m简支梁桥为工程背景,基于有限元法和梁轨相互作用原理,建立了轨道-梁-墩-基础一体化计算模型,研究收缩与徐变效应、梯度温度模式、墩高等对纵向力的影响规律,并与常规纵向力进行了对比分析.研究结果表明:主梁收缩与徐变引起的梁轨纵向力由纵向缩短效应控制,与竖向挠曲效应关系较小,且该项纵向力大于伸缩力或挠曲力,使得桥台产生较大的水平力;指数分布和线性分布梯度温度模式计算得到的纵向力分别约为制动工况下的20%~30%和50%~100%,指数分布梯度温度模式相对合理,温度曲线参数对纵向力的影响有限,建议尽快制定合理、统一的桥墩梯度温度荷载. 

Special Longitudinal Forces between Continuous Welded Rail and Long-Span Simply Supported Beam Bridge with High Piers and Their Influences

In order to investigate the special longitudinal forces between a continuous welded rail and a bridge caused by shrink and creep of the main girder and gradient temperature load of piers, a simply supported beam bridge with a standard span of 64 m was selected as the case study, and an rail-girder-pier-foundation integrated calculation model was established by finite element method (FEM) and bridge-rail interaction theory. On this basis, the influence laws of shrink and creep effects, gradient temperature modes, and pier height on longitudinal forces were probed into in comparison with four common types of longitudinal forces. The results show that the longitudinal force induced by shrink and creep of the main girder is dominated by the longitudinal shortening effect rather than the vertical bending effect. This kind of longitudinal force is higher than the contractility or bending force, and it causes a large horizontal force at abutments. The longitudinal forces caused by gradient temperature in exponential and linear distribution modes account for 20%- 30% and 50%- 100%, respectively, of the case of brake force. In general, the exponential distribution mode of gradient temperature is more reasonable as different parameters result in limited variations in longitudinal forces. Due consideration should be given to the formulation of reasonable and uniform gradient temperature load of piers.