Research On Adaptability Of Transportans Of Overload Vehicles On Medium And Small Span PC Simple Beam Bridge

With the development of vehicles that are large-sized, have trailers, and shipcontainers, number of overload vehicles is increasing at a high speed, which is to harm safety of highway bridge. Even overload vehicles do not break bridge directly, they tends to lead some diseases to structure, which accumulated to someextend will eventually bring damage to structure. When load of vehicles beyond designed load, severe influence to safety and longevity of bridge is to be made.In China,Highway bridge design load specifications was changed somewhat for several times. In General specification for highway bridge design(JTG D60—2004),the design of bridge structure takes roadway load as designed load, which obscures criterion of passing vehicles that are overload. So, it is necessary to make a clear and specific criterion for overload vehicles. Based on a project of adaptability of overload transportation in expressway of Chongqing, some work isdone as follows:①The situation of all the vehicles that are over 55tons within two and a half months in Chongqing is investigated, which suggests that most of these vehicles are between 55tons and 80tons, whose axles are from four to six, transporting on Chengyu expressway, Yusui expressway and Yufu expressway.②The criteria of overload vehicle in other countries are sumarized, which are compared to Chinese criterion of overload vehicle, suggesting that the indication of vehicle load was in terms of vehicle group and that is in terms of roadway load, which makes formal clear overall limit set out standards obscure.③According to result of investigation of passing vehicles on Chongqing's expressways, four types of vehicles are studied, which are four-axle vehicle(1+1+22), five-axle vehicle(1+2+222), six-axle vehicle(1+22+222) and load plate vehicle. By analysis of these vehicles samples, wheelbase of four types vehicles and some relative parameters are fixed on, and models of four types vehicles areestablished.④The four types of vehicles and PC Simple beam bridge of three types of span (16m, 20m,30m) are studied in detail. Thus, the overall limits set-out standards and limited set of local standards of the bridge of the three types of spans on which the four types of vehicles steer are given.