基于运营纵坡控制的大跨铁路和公铁合建桥竖向刚度设计方法

Vertical Stiffness Design Method Based on Longitudinal Gradient Control in Service Period for Long-Span Rail-cum-Road Bridge

为合理设计大跨铁路和公铁合建桥梁的竖向刚度,提出了一种基于运营纵坡控制的竖向刚度设计方法,该方法以保障列车安全通行、乘客乘坐舒适性为目标,选取最大牵引纵向坡度、最小溜逸纵向坡度、纵向坡度差、曲率半径以及车桥动力响应为控制指标,对桥梁的竖向刚度进行控制,采用该方法对某公铁合建三塔斜拉桥方案进行竖向刚度设计验证。结果表明:该方法能较好地实现大跨铁路和公铁合建桥梁的竖向刚度设计,在保障结构和行车安全的前提下能够降低工程投资、提高桥梁设计的经济性。算例验证结果显示该方法的各项计算结果均满足各控制指标要求,竖向刚度合理。该方法还可根据运营纵向坡度反推合理的成桥纵向坡度和桥面线形。

To have a rational design of vertical stiffness of the long-span rail-cum-road bridge,a method premised on the control of longitudinal gradient in the service period is proposed.With the objectives of ensuring the running safety of trains and passenger comfort,the indexes,such as maximum traction longitudinal gradient,minimum runaway longitudinal gradient,longitudinal gradient difference,curvature radius and vehicle-bridge dynamic response,are taken into account to control the vertical stiffness of the bridge.The method has been used to verify the vertical stiffness design of a real three-pylon cable-stayed bridge accommodating both railway and highway.The engineering practice proves that the method can lead to rational vertical stiffness design for the long-span rail-cum-road bridge,reduce the engineering investment and improve the cost-effectiveness of the bridge design,with the guaranteed structural and running safety.The case verification indicates that the calculation results meet the required standards,and the vertical stiffness is rational.The method can also be applied to deduce the rational longitudinal gradient and deck geometry of the complete bridge.