Research On Load Model Of Actual Operating Vehicles On Typical Highway

Vehicle live load and fatigue load are two of the most important vehicle loads on highway bridges. On the one hand, our country is very large, and unbalanced development between different regions leads to significant difference between vehicle load models; on the other hand, there is a big discrepancy between vehicle load of actual operating vehicles and that for design. Therefore, this research, based on the measured data acquired by weigh-in-motion (WIM) system, is mainly concentrated on live load model and the fatigue load model of actual operating vehicles on highway Bridges.The main work can be summarized as follows:(1) In this paper, Xinyihe River Bridge was selected as the engineering background, which is located in Jinhu Highway. Based on about 15 million measured data of actual vehicles acquired by WIM system, statistical analysis was carried on the distribution features of the vehicle parameters. Then, vehicle live load model of six kinds of girder bridges, including Xinyihe River Bridge, was established under normal operating status with the method accounting for the development of code.(2) With Xinyihe River Bridge as the engineering background again, vehicle live load model of congested operating status and road merging operating status was established based on equilibrium renewal process theory.(3) Taking Guanhe River Bridge of Coastal Highway as the engineering background, comparison analysis was conducted on the difference between patterns and values of fatigue load model in the code for highway bridges at home and abroad. On the basis of statistical analysis toward actual vehicle parameters measured by WIM system, fatigue load spectrum and standard fatigue truck were calculated, and comparison was conducted on cables’fatigue action caused by various fatigue load models with the intention of fatigue assessment of the cables on Guanhe River Bridge.The main conclusions are as follows:(1) Long-term measured data acquired by WIM system at Xinyihe River Bridge showed that, in terms of the number of vehicles, the number of heavy-load trucks during the day is more than that at night, and obviously seasonal difference is observed about vehicle number, even so, the overall number is in steady with slight growth; when it come to the gross vehicle weight, the proportion of heavy-load trucks decrease successively from the outside to the inside lane, and from southbound to northbound obviously. Live load model of actual operating vehicles at the right part of Xinyihe River Bridge is 1.4 times the highway load I-grade, and 1.22 of the left.(2) When traffic flow of two directions cross Xinyihe River Bridge through the left part of it (i. e., road merging operating status), live load model of actual operating vehicles is 1.25 times the highway load I-grade, which is close to the live load of normal operating status. At congested operating status, Live load model of the right part of Xinyihe River Bridge is 2.1 times the highway load I-grade, and 1.8 of the left, which is increased by 0.7 times and 0.6 times respectively compared with normal operating status.(3) Three fatigue load models for Guanhe River Bridge were established:"fatigue load model 1" is fatigue load spectrum consisting of five kinds of vehicles; "fatigue load model 2" is a standard fatigue truck consisting of six axles; "fatigue load model 3" consists of the direct application of recorded traffic data by appropriate statistical and projected extrapolations. Fatigue action suffered by several cables were calculated respectively using "fatigue load model 1" and "fatigue load model 3",results are very similar, also it was showed that fatigue reliability of cables on Guanhe River Bridge is high, and the result based on fatigue load spectrum is more conservative.