摘要
为研究斜拉索在腐蚀环境和疲劳荷载长期作用下的拉索使用状态,以某西南地区服役了20多年的斜拉索为试验对象,通过拉索力学性能试验和有限元模拟,建立了腐蚀-疲劳耦合作用下的拉索剩余承载力和疲劳寿命评估方法。首先,通过高倍率显微镜获取全方位的钢绞线腐蚀图像,依据规范要求将拉索内钢绞线划分了腐蚀等级,进行了钢绞线拉伸破断和拉伸疲劳试验,统计了钢绞线的极限抗拉强度和疲劳寿命数据,拟合了该拉索钢绞线材料的S-N曲线。然后,针对车型、车重和车间距3个车流参数的随机特征,建立了随机车流模型模拟索力时程变化,并基于实际监测的索力数据对模拟数据进行了多参数对比分析。最后,引入减少引子K,评估了拉索的整体承载力,采用雨流计数法对模拟的索力数据进行处理,结合损伤累计理论计算出了拉索的剩余疲劳寿命。结果表明:拉索中的钢绞线极限抗拉强度均未满足规范要求,最大极限抗拉强度仅为1852.186 MPa,计算得出拉索整体极限抗拉强度降低了4%。模拟索力与实际索力的极值、均值、95%分位值误差不到5%,平均绝对百分比误差为5.3875%,小于10%,证明随机车流模型具有较好的可靠性。拉索钢绞线材料的S-N曲线的拟合优度为0.994,对预测该拉索疲劳寿命具有较强的准确性,最后计算得出拉索的疲劳寿命约为4.6 a。
To investigate the stay cables condition in the corrosive environment and under long-term fatigue loading,the study was conducted with the bridge stay cables in southwest of China,which had been in service over two decades.The residual bearing capacity calculation and fatigue life evaluation method was developed by using the mechanical property tests and finite element simulations.First,the high-magnification microscopy was used to obtain the comprehensive corrosion images of steel strand cables.According to the current standards,the corrosion levels of these strands were classified.The tensile fracture and fatigue tests were performed.The data of ultimate tensile strength and fatigue life were counted.The S-N curves were fitted for the material of strand cables.Subsequently,the stochastic traffic flow model was established to simulate the cable forces varying with time,taking into account the random characteristics of vehicle type,weight,and spacing.The simulated data were compared with the actual monitored cable force data by using the multi-parameter analysis.Finally,a reduction factor K was introduced to assess the overall bearing capacity of stay cables.The simulated cable force data were processed by using the rain flow counting method.The residual fatigue life of cable was calculated based on the cumulative damage theory.The result indicates that the ultimate tensile strengths of steel strand cables do not meet the current standard requirements.The maximum ultimate tensile strength is only 1852.186 MPa,representing 4%decrease in the overall ultimate tensile strength of cables.The simulated cable forces show less than 5%discrepancy of extreme values,mean values,and the 95th percentile value compared with the actual measurements.The average absolute percentage error is 5.3875%,which is below 10%,indicating the reliability of stochastic traffic flow model.The fit goodness of S-N curve of stay cable steel strand material is 0.994,which possesses the relatively high accuracy in predicting the fatigue life of st
作者
张洪
李明阳
王良辉
余建
李厚萱
ZHANG Hong;LI Ming-yang;WANG Liang-hui;YU Jian;LI Hou-xuan(State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing 400074,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Chongqing Municipal Facilities Operation Support Center,Chongqing 401120,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2024年第12期116-127,共12页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(52278291,U20A20314)
重庆市自然科学基金项目(CSTB2022NSCQ-LZX0006,CSTB2022TIAD-KPX0205)。
关键词
桥梁工程
疲劳寿命
数值模拟
斜拉索
随机车流
bridge engineering
fatigue life
numerical simulation
stay cable
random traffic flow
