基于增设支撑的重载铁路小跨度梁加固技术

Reinforcement Technology on Short-span Bridges for Heavy-haul Railway Based on the Method of Adding Supports

研究目的:小跨度梁是重载铁路运输中的重要组成部分和薄弱环节,其服役性能易受列车轴重的影响,难以满足重载铁路扩能的需求。本文以重载铁路常见12.0 m跨度梁为例,提出一种增设竖向支撑改变结构体系的小跨度梁简易加固方法,并结合数值模拟和实桥试验测试,开展加固参数影响分析和小跨度梁加固前后静动力适应性研究,确定合理加固参数。研究结论:(1)增设支撑加固法基本原理是在小跨度梁原支座两侧增设竖向支撑,通过减小桥梁跨度和改变桥梁体系结构来降低梁体内应力,进而提高桥梁承载能力和使用条件;(2)增设竖向支撑刚度合理取值为原支座刚度的50%,加固距离则以安装在墩帽边缘处为宜,增设支撑纵向宽度需与原支座一致;(3)采用增设支撑加固后,桥梁结构跨中挠度、横向振动加速度和竖向振幅以及支座竖向位移等静动力性能指标改善显著,降幅均达到20%以上,桥梁横向振幅、竖向加速度改善程度略小;(4)本文提出的加固方法可为既有铁路桥梁强化改造及养护维修提供参考和借鉴。

Research purposes:The short-span bridges are an important component and weak link of heavy-haul railway transportation.The service performance of short-span bridges is easily affected by axle load of freight train,making it difficult to meet the needs of capacity expansion of heavy-haul railways.Taking the common short-span bridge with a span of 12.0 m as an example,a simple reinforcement method for short-span bridges by adding vertical supports to change the structural system is proposed to improve the bearing capacity.Combined with numerical simulation and actual bridge test,the influence analysis of reinforcement parameters and the study of static and dynamic adaptability before and after reinforcement of short-span bridges are carried out,and reasonable reinforcement parameters are determined.Research conclusions:(1)The basic principle of adding support reinforcement method is to add vertical supports on both sides of the original supports of short-span bridges.By reducing the bridge span and changing the bridge system structure,the internal stress of the bridge is reduced,thereby improving the bearing capacity and service conditions.(2)The reasonable value for adding vertical support stiffness is 50%of the original support stiffness,and the reinforcement distance should be installed at the edge of the pier cap.The longitudinal width of the added support should be consistent with the original support.(3)After adding support reinforcement,the static and dynamic performance indicators of the bridge structure,such as mid span deflection,lateral vibration acceleration and vertical amplitude,as well as vertical displacement of the support,have significantly improved,with a reduction of more than 20%.The improvement degree of lateral amplitude and vertical acceleration of the bridge is slightly small.(4)The reinforcement method proposed in this paper can provide reference for the strengthening and maintenance of existing railway bridges.