西南山区高速公路桥梁标准疲劳车辆荷载研究

摘 要：疲劳车模型在桥梁疲劳评估中有着非常重要的作用，本文根据动态称重系统获得的车辆数据，并以等损伤度为理论基准，推导出适用于中国西南山区高速公路桥梁的3轴标准疲劳车模型。车辆统计数据和疲劳损伤度模拟计算表明，超过一半的疲劳损伤由6轴车引起，故根据统计数据以6轴车为原型设计出简化的3轴标准疲劳车模型，并根据Miner线性累积损伤法则，以实际车辆导致的损伤度为目标对疲劳车模型轴重和轴距进行修正。同时，本文针对西部山区高速公路桥梁提出两项建议：其一为基于弯矩概率函数曲线分析，建议最大应力幅峰值取为等效应力幅的3倍而不是AASHTO所规定的2倍，这主要由于该地区部分车辆超载较多所致；其二为BS5400疲劳车模型是实际车辆引起疲劳损伤的1.15倍从而高估了本地区的疲劳损伤，而AASHTO疲劳车引起的疲劳损伤与实际车辆导致的损伤也基本一致，故建议在西部山区高速公路疲劳车规范的选择时，宜选择AASHTO规范，但应根据实际通行车辆对疲劳车通行量进行修正。

Standard fatigue truck on montane speedway bridge

The fatigue truck model is essentially important for fatigue evaluation.A 3-axle fatigue truck model was developed based on the weigh-in-motion traffic data and with the help of an analytical model of bridge on the montane speedway in southwest China.The truck traffic data show that the fatigue damage is dominated by the 6-axle trucks,so,the simplified 3-axle fatigue truck model was established in the light of the 6-axle truck statistic data.The damage accumulations evaluated by the proposed fatigue truck model can accord well with the actual damage accumulations.Based on the analysis of cumulative probability function of the bending moment and considering the overload,the peak stress magnitude was suggested to take a level of 3 times of the equivalent stress magnitude instead of the 2 times stipulated in AASHTO.The damage accumulations obtained from the simulation of the truck database were compared with those evaluated by BS5400,AASHTO and the proposed fatigue truck model.The proposed fatigue truck and AASHTO fatigue truck with the actual daily flow of trucks were suggested to be used in fatigue evaluation of the bridge on montane speedway in southwest China.BS5400 is improper which relatively overestimates the damage.