货运繁重公路的车辆荷载谱和疲劳车辆模型

为研究货运繁重公路的车辆荷载谱和疲劳车辆模型, 基于佛山平胜大桥的动态称重系统采集的多时段车流数据, 归类出了车辆荷载谱的10类代表车型, 分析了代表车型的轴距、质量、轴重和超载数据, 以及沿不同车道的车辆和轴重分布特性, 提出了可用于钢桥疲劳评估的车辆荷载谱; 以疲劳加载率最大的六轴车辆为原型, 基于疲劳损伤等效原则分别提出了桥梁单向重载车道的疲劳车辆模型和简化疲劳车辆模型。计算结果表明: 平胜大桥呈现货运繁重公路的典型特征, 车辆日均通行总量达到了45 065veh, 约为《AASHTO LRFD》定义的日均通行量20 000veh的2.3倍; 疲劳车辆在全部交通流中的比例为51.6%, 为《AASHTO LRFD》定义的20.0%的2.6倍; 货车占疲劳车辆总数的45.2%, 主要分布于重载车道, 而且通行货车超载比例占到相应车型的30%⁷0%, 最大超载货车达到了132.5t;两轴货车超载率为29.0%, 等效质量达到17.5t, 后轴等效轴重达到12.1t, 因而不能忽略两轴货车的疲劳加载贡献。对比《AASHTO LRFD》五轴标准疲劳车辆模型(前轴轴重为2.6t, 中间双联轴和后面双联轴的单轴轴重均为5.4t) 和简化标准疲劳车辆模型(前轴为2.6t, 中轴和后轴均为10.8t), 提出的六轴单向疲劳车辆模型总质量为33.1t, 前轴轴重为3.6t, 中间双联轴和后面三联轴的单轴轴重均为5.9t;简化单向疲劳车辆模型的前轴轴重为3.6t, 中轴和后轴分别为11.8、17.7t;针对重载车道提出的六轴疲劳车辆模型总质量达到了36.5t, 前轴轴重为4.0t, 联轴中的单轴轴重均为6.5t;对应的重载车道简化疲劳车模型的前轴轴重为4.0t, 中轴和后轴轴重分别为13.0、19.5t。

Vehicle loading spectrum and fatigue truck models of heavy cargo highway

In order to research vehicle loading spectrum and fatigue truck models of heavy cargo highway, the multi-period traffic flow data based on a weight-in-motion system located on Pingsheng Bridge in Foshan were used to present 10 representative vehicle types. The wheelbases, masses, axle loads and overload data of representative vehicle types were analyzed, the distributions of vehicle types and axle loads on each lane were studied, and vehicle loading spectrum was proposed to evaluate the fatigue performance of steel bridge. The six-axle truck with the largest fatigue loading rate was taken as prototype, the fatigue truck model and simplified fatigue truck model of unidirectional heavy load lane of bridge were proposed based onthe equivalent rule of fatigue damage. Calculation result shows that Pingsheng Bridge presents the typical features of heavy cargo highway, the average daily traffic is 45 065 veh and 2.3 times as large as 20 000 veh in AASHTO LRFD. The proportion of fatigue vehicles is 51.6% in all traffic flow and 2.6 times as large as 20.0% in AASHTO LRFD. The proportion of trucks is 45.2% in all fatigue vehicles, they mainly distribute on heavy lanes, overload trucks accounts for 30%-70% of corresponding vehicle types, and the maximum mass of overload truck reaches 132.5 t. The overload rate of two-axle trucks is 29.0%, the equivalent mass is 17.5 t, and the equivalent mass of rear axle is 12.1 t, therefore, the fatigue loading effect of two-axle trucks should not be ignored. Compared with AASHTO LRFD's five-axle standard fatigue vehicle model (the front axle load is 2.6 t, and the single axle loads of mid and rear two-axle group are 5.4 t) and the simplified fatigue vehicle model (the front axle load is 2.6 t, and the mid axle load and rear axle load are 10.8 t), the total mass of six-axle unidirectional fatigue truck model proposed in this paper is 33.1 t, the front axle load is 3.6 t, and the single axle loads of mid two-axle group and rear three-axle group are 5.9 t. The front axle load of simplified one-direction fatigue truck model is 3.6 t, the mid axle load is 11.8 t, and the rear axle load is 17.7 t. The total mass of six-axle fatigue truck model proposed for the heavy lanes reaches 36.5 t, the front axle load is 4.0 t, and each axle load of conjoint-axle is 6.5 t. The front axle load of simplified fatigue vehicle model for the heavy lanes is 4.0 t, the mid load is 13.0 t, and the rear axle load is 19.5 t.