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.