考虑加载历史的小半径曲线桥梁梁轨相互作用分析

Analysis of track-bridge interaction for small radius curved bridges considering loading history

目前,大部分考虑加载历史的梁轨相互作用研究都集中在直线桥梁上,针对曲线桥梁,尤其是小半径曲线桥梁,梁轨相互作用的研究相对较少。采用理想弹塑性滞回阻力模型模拟扣件纵向阻力,运用有限元软件,建立以城东特大桥为研究对象的钢轨-桥梁-墩台三维有限元空间力学计算模型,研究曲线半径对于梁轨相互作用的影响,探究了多荷载耦合作用、往复荷载作用以及循环荷载作用下考虑加载历史效应的曲线桥梁梁轨相互作用情况,并提出“拉力百分比”以及“压力百分比”的概念以便分析曲线半径对传统线性叠加法误差的影响。结果表明,曲线桥梁中梁轨纵、横向相互作用分别与曲线半径成正、反比,相关数据改变幅度与曲线半径成反比且当曲线半径超过800 m时基本收敛,此时可采用“以直代曲”的简化算法;曲线半径对于横向梁轨相互作用影响程度大于纵向,相较于挠曲、制动工况,伸缩工况受曲线半径影响更加显著;多荷载耦合作用下,采用传统线性叠加法相较于考虑加载历史更为保守且温度荷载起主要贡献;考虑加载历史时钢轨在往复荷载作用下会产生不可忽视的残余内力,且在循环荷载作用下将会产生收敛于第1次往复荷载下的残余内力,这是扣件纵向阻力的弹塑性滞回特性决定的;线性叠加法误差与曲线半径具有相关性,相较于挠曲、制动工况,伸缩工况下对其更为敏感。研究结果可为考虑加载历史下曲线桥梁结构设计提供参考。

At present most of the research on track-bridge interaction considering loading history is focused on linear bridges,for curved bridges,especially those with small radius.There are relatively little research on trackbridge interaction.In this paper,the ideal elastic-plastic hysteresis resistance model was used to simulate the longitudinal resistance of the fastener.A three-dimensional finite element spatial mechanics calculation model of rail-bridge-pier was established using finite element software with the Chengdong Special Bridge as the research object.The effect of curve radius on the track-bridge interaction was investigated.The track-bridge interaction of the curved bridge under multiple load coupling,reciprocal load and cyclic load considering the loading history effect was investigated.The concepts of“tension percentage”and“pressure percentage”were proposed to analyze the influence of curve radius on the error of conventional linear superposition method.The results show that the track-bridge longitudinal and lateral interactions in curved bridges are positively and inversely proportional to the curve radius.The relevant data changes are inversely proportional to the curve radius and converge basically when the curve radius exceeds 800 m.The simplified algorithm of“straight instead of curved”can be adopted at this time.The influence of curve radius on lateral track-bridge interaction is greater than that of longitudinal.The influence of curve radius on expansion and contraction is more significant than that of flexural and braking.Under multiple load coupling,the traditional linear superposition method is more conservative than considering the loading history and the temperature load is the main contribution.Considering the loading history,the rail will generate non-negligible residual internal force under reciprocating load,and the residual internal force under cyclic load will converge to that under the first reciprocating load.This is determined by the elasticplastic hysteretic characteristics of the longitudinal resistance of the fastener.Linear superposition method error and curve radius has a correlation,compared to the flexural,braking conditions,expansion and contraction conditions are more sensitive to it.The results can provide reference for structural design of curved bridges considering loading history.