Abstract: The bridge collapses continuously occurred recent years in many provinces. It produced all kinds of fatigue problems when the overloading vehicles frequently passed through the bridge. In combination with the key highway bridges in service in Hebei province, the overloading vehicles load spectrum was monitored. Through the traffic investigation，high frequency vehicle model, the distribution of vehicles flow, the vehicle’s own properties (wheelbase, axle load) and so on were statistically analyzed. According to the principle of equivalent fatigue damage, the model of 5 kinds of daily operation vehicle load was deduced based on the measured data and the fatigue loading spectrum was established. To compare with highway-I automotive design load effect, it is concluded that when the span is less than or equal to 25 m, its vehicle load should be increased to about 1.3 times; When the span is longer than 25 m, its vehicle load should be raised to about 1.2 times.

Key words: bridge engineering, overload vehicle, load spectrum, the fatigue damage equivalent principle, traffic investigation, expressway bridge

摘要： 针对近年来各省连续发生多起桥梁垮塌事件，重载车辆频繁驶过桥梁的过程容易使桥梁产生各种疲劳问题。结合河北省高速公路在役重点桥梁进行重载车辆荷载谱监测，通过交通量调查，统计分析出现频率较高的车辆模型、车流量的分布、车辆的自身性质(轴距、轴重)等。依据疲劳等效损伤原理，推导出基于实测的5种日常营运重载车辆荷载模型，建立疲劳荷载谱。通过与公路-Ⅰ级汽车荷载作用效应进行对比，得出当跨径小于等于25 m时，应将其汽车荷载提高至1.3倍左右;当跨径大于25 m时，应将其汽车荷载提高至1.2倍左右。

关键词: 桥梁工程, 重载车辆, 荷载谱, 疲劳等效损伤原理, 交通调查, 高速公路桥梁