考虑卡车横向分布影响的公路桥梁车辆荷载模型研究

In the same-direction multi-lane bridge of expressways,the heavy vehicles, such as trucks, are prone to travel in the right lane,and the light vehicles to travel in the left lane,so vehicle load of different lane is remarkably different. At present, systematic study has been conducted in the vehicle load model,however,enough caution were not given in the lateral distribution of truck, the impact of the truck lateral distribution has not been considered in the design of new bridge and the widening of existing bridge. The aim of this research is to model the vehicle load and propose the partial factor of the vehicle load.In this research proposal,the same-direction four lane bridge was taken as the object of study.After getting the probability of simultaneous truck presence in adjacent lanes and WIM car data, the vehicle load effect samples will be calculated,and systematic research will be conducted in the difference of load effect in different lanes.The distribution type and parameter of the maximum vehicle load effect in design reference perieod will be extrapolate by using the vehicle load effect, and vehicle load model of per lanes and its design partial factor will be proposed.The research conclusions can be as the reference to the revision of vehicle load model for the highway bridge design specification,and also can provide a theoretical basis for the selection of vehicle load standard in widening design of existing highway bridge.

在同方向多车道的高速公路桥梁上，卡车倾向于在右侧车道行驶，将左侧车道让与轿车、客车等快速车辆，不同车道上行驶的车辆存在显著的差异。目前关于车辆荷载模型已有深入系统的研究，但卡车横向分布效应尚未引起重视，新桥的设计和既有桥梁的拼宽均没有考虑这种效应。本项目旨在建立考虑卡车横向分布影响的车辆荷载模型，并提出车辆荷载的分项系数。以高速公路中小跨径同方向四车道桥梁为研究对象，基于动态称重（WIM）数据，并实测不同车道上卡车的并行概率，计算车辆荷载效应样本，研究卡车横向分布对各车道实际载荷水平的影响，由此推算设计基准期内主梁的车辆荷载效应最大值分布函数，建立同方向四车道桥梁各车道的车辆荷载模型，提出车辆荷载的分项系数。本研究将为公路桥涵设计车辆荷载模型的修订提供参考，更为既有高速公路桥梁拼宽设计车辆荷载的选择提供理论依据。

在桥梁拓宽工程中，同方向两车道桥梁拼宽为同方向四车道桥梁的汽车荷载标准取值问题，一直面临很困难的抉择，标准选取太高，则原桥面临大量加固，取值太低则在安全性方面面临危险。本项目针对中小跨径桥梁对此进行了研究。首先，获得了京港澳高速、深圳某段高速的各车道的WIM数据。然后，现场观测了各车道卡车并行概况，并计算了以卡车单位时间通行量为自变量的卡车并行概率，研究了车辆荷载模型的建立方法，并对同向四车道桥梁进行了可靠度分析。研究结果表明：（1）极少数重车对车辆荷载起主导作用，普通车辆几乎不起作用；（2）实际车辆荷载效应远大于JTG D60-2004规范，也大于JTG D60-2015规范；（3）观测发现内侧车道没有卡车通过，卡车超车时会短暂在第二车道行驶，卡车主要在第三车道和第四车道通行，（4）拼宽后，位于第一车道和第二车道的主梁可靠度极高，第三车道可靠度下降。本项目的研究成果预计可用于桥梁工程的拓宽改建，并为规范修订提供参考。