基于车轨桥耦合模型的重载铁路预应力混凝土T梁剩余疲劳寿命分析

Residual life evaluation of heavy haul railway prestressed concrete T-beams based on train-track-bridge coupling model

多跨预应力混凝土简支T梁桥在重载铁路线路中应用广泛,随着线路年运量的增长及大轴重长编组货物列车的运行,车桥动力响应加剧,桥梁发生疲劳破坏风险增大。为了解决这些问题,本文建立重载列车-钢轨-预应力混凝土简支T梁桥精细化分析模型,精确求解重载列车过桥时的车桥动力响应;采用雨流计数法统计分析桥梁普通受拉钢筋应力时程,获得疲劳应力谱;基于Miner准则和Corten-Dolan准则,计算典型疲劳列车单次过桥时的桥梁疲劳损伤;利用灰色GM(1,1)模型来预测线路未来年运量,并对预应力混凝土T梁疲劳损伤进行分析,对剩余寿命进行评估。研究结果表明:随着货车编组数量增加,列车过桥引起的桥梁动力响应峰值趋于稳定,仅应力时程中间周期性波动部分相应延长;由于考虑了结构非线性累积损伤的影响,在相同疲劳列车作用时,按照Corten-Dolan准则计算的桥梁疲劳损伤比按Miner准则计算的桥梁疲劳损伤大7.2%左右;4种典型疲劳列车(C_(64)-N-66、C_(70)-1-116、C_(80)-1-108、C_(80)-2-216)独立运送相同运量货物时引起的桥梁损伤之比为1?0.768?0.543?0.457;在线路容许条件下,宜优先开行大轴重且更长联编组的货物列车,在运量相同时可有效降低对桥梁的疲劳损伤;基于车-轨-桥精细化模型和Corten-Dolan准则,采用等效列车历史运营谱和未来运营谱来考虑年运量和疲劳列车大轴重长编组的发展趋势,可更精确评估重载铁路预应力混凝土简支T梁桥的剩余疲劳寿命。

Multi span prestressed concrete simply supported T-beam bridge is widely used in heavy haul railway lines.With the growth of annual traffic volume of the line and the operation of long marshalling freight trains with large axle load,the dynamic response of the vehicle bridge is intensified,which increases the risk of fatigue failure of the bridge.The refined analysis model of heavy load train-rail-prestressed concrete simply supported T-beam bridge was established to accurately solve the dynamic response of the vehicle bridge when heavy load train passed the bridge.Then,the rain flow counting method was used to statistically analyze the stress time history of the common tensile reinforcement of the bridge,and the fatigue stress spectrum was obtained.Based on Miner criterion and Corten-Dolan criterion,the fatigue damage of the bridge was calculated when a typical fatigue train passes the bridge for a single time.The grey GM(1,1) model was used to predict the future annual traffic volume of the line,and the fatigue damage analysis and residual life assessment of the prestressed concrete T-beam were carried out.The results show that with the increase of the number of freight trains,the peak value of bridge dynamic response caused by train passing bridge tends to be stable,and only the periodic fluctuation part in the middle of the stress time history extends correspondingly.Considering the influence of structural nonlinear cumulative damage,the fatigue damage of the bridge calculated according to Corten Dolan criterion is 7.2% larger than that calculated according to Miner criterion under the same fatigue train action.The ratio of bridge damage caused by four typical fatigue trains(C_(64)-N-66,C_(70)-1-116,C_(80)-1-108,C_(80)-2-216) when independently transporting goods of the same volume is 1:0.768:0.543:0.457.Under the allowable conditions of the line,priority should be given to running freight trains with large axle load and longer combined marshalling,which can effectively reduce the fatigue damage to the bridge when the traffic volume is the same.Based on the refined vehicle track bridge model and Corten Dolan criterion,the equivalent train historical operation spectrum and future operation spectrum are used to consider the development trend of annual traffic volume and long marshalling of fatigue trains with large axle load,which can more accurately evaluate the residual fatigue life of prestressed concrete simply supported T-beam bridges on heavy haul railways.