风-车流耦合作用下悬索桥吊索钢丝的双蚀坑损伤演化及疲劳寿命研究

Damage Evolution and Fatigue Life of Steel Wire with Double Corrosion Pits for Suspension Bridge under Wind-and Traffic-loads

基于连续介质损伤力学,采用ANSYS建立双蚀坑钢丝模型,结合某悬索桥的风-车流-桥耦合振动分析所得吊索应力时程数据,研究了不同工况下的带两个主蚀坑的该悬索桥吊索钢丝的疲劳损伤演化规律,探讨风速、车流、吊索位置、蚀坑形状参数、双蚀坑形状不对称等因素对双蚀坑吊索钢丝损伤演化规律和疲劳寿命的影响。结果表明:双蚀坑吊索钢丝的腐蚀疲劳寿命对高风速更加敏感;在同一风速下,车流量越大,双蚀坑吊索钢丝的腐蚀疲劳寿命越短;在风-车流耦合作用下,双蚀坑吊索钢丝的腐蚀疲劳寿命明显低于无车流工况下的;位于桥梁跨中的短吊索钢丝比地面长吊索钢丝和1/4跨吊索钢丝的腐蚀疲劳寿命更短;蚀坑的深宽比越大,蚀坑形状越尖锐,双蚀坑吊索钢丝的腐蚀疲劳寿命越短;当双蚀坑形状不对称时,吊索钢丝的腐蚀疲劳寿命主要由深宽比较大的蚀坑决定。

To investigate the course of fatigue damage evolution and fatigue life of the corroded steel wire with double corrosion pits for suspension bridges,a model of high-strength steel wire with dou-ble corrosion pits was established through finite element software ANSYS.Based on continuum damage mechanics combined with the time-history data of sling stress of suspenders acquired from the wind-traf-fic-bridge coupling vibration analysis,the course of fatigue damage evolution for the high-strength steel wire with double corrosion pits under different operation conditions was studied.Meanwhile,the influence of wind speed,traffic load,suspender position,shape of corrosion pit and shape of asymmetric double corrosion pits on the course of damage evolution and fatigue life of the high-strength steel wire with dou-ble corrosion pits was discussed respectively.The results show that the corrosion fatigue life of the steel wire with double corrosion pits is more sensitive to high wind speed rather than low wind speed.More-over,the corrosion fatigue life of steel wire decreases with the increase of the traffic flow under the same wind speed.When the wind and traffic flow are coupled,the corrosion fatigue life of high-strength steel wire with double corrosion pits is obviously lower than that without traffic flow.The short suspender at the bridge mid-span has shorter corrosion fatigue life than that of the longest ground suspender and suspend-er located at 1/4 span.Furthermore,it is found that the greater the depth-width ratio of the corrosion pit,the sharper shape the corrosion pit,thus the shorter the corrosion fatigue life of the steel wire with double corrosion pits.When the shape of double corrosion pits is asymmetric,the corrosion fatigue life of sus-pender steel wire is mainly determined by the pits with larger depth-width ratio.