基于轮式滚动加载的正交异性钢桥面板疲劳试验设计

Design of Fatigue Test for Orthotropic Steel Deck Based on Wheel Running Loading

能模拟车辆荷载通过效应的疲劳模型试验是研究正交异性钢桥面板疲劳性能的有效手段。利用国内首台自主研发的桥面结构专用轮式滚动疲劳加载装置,以广东虎门二桥坭洲水道桥为依托工程,研究了基于轮式滚动加载的正交异性钢桥面板疲劳试验设计问题。首先,根据实桥交通需求分析,合理确定实桥疲劳荷载谱;其次,计算疲劳敏感部位热点在疲劳荷载谱各车型作用下的应力历程,采用雨流计数法计算应力谱,根据Miner疲劳损伤累积理论转化为每种车型通过1次的等效应力幅,结合交通量预测计算实桥各构造细节在设计寿命期内的疲劳累积损伤;最后,根据设备性能参数,分别计算橡胶轮双轴加载和钢轮单轴加载下试验模型各细节的等效应力幅,通过与实桥钢桥面板各细节的疲劳累计损伤等效,从而确定试验加载轴类型、加载水平以及对应各细节的等效作用次数。研究成果对改进正交异性钢桥面板疲劳试验设计有重要参考意义。

The fatigue model test which can simulate the load effect of passing vehicles is an effective method to study the fatigue performance of orthotropic steel deck. Based on the first self-developed wheel running fatigue loading system for bridge structures in China,taking the Nizhou Channel Bridge of Guangdong Humen 2nd Bridge as the background project,we studied the design of fatigue test for orthotropic steel deck based on wheel running loading. First,we determined the fatigue load spectrum for the real bridge in accordance with the traffic demand analysis. Second,we calculated the stress histories of the hot points in fatigue-prone details for the passage of each vehicle in the fatigue load spectrum,evaluated the stress spectra using the rain-flow counting method,and converted to the equivalent stress ranges for one passage of each vehicle based on the Miner damage accumulation theory,then computed the fatigue damage summations of various structural details for the bridge design life period with the traffic volume forecast. Third,we calculated the equivalent stress ranges for the details in the test model under the rubber-wheel dual-axle load and the steel-wheel single-axle load respectively in accordance with the performance parameters of the loading equipment,and determined the load-axle type,loading level,and loading numbers corresponding to various details with the equivalent fatigue damage to the bridge in the test. This research is beneficial to improve the fatigue test design of orthotropic steel decks.