Research On The Mechanical Properties Of Prestressed Single Tower Single-sided Cable-stayed Slab Bridge Under Vehicle Congestion

Since the reform and opening up,with the rapid development of China's economy and the gradual deepening of the construction of modernized and structured cities,the number of motor vehicles in China has been increasing.Vehicle congestion has become a key problem to be solved in the development of China's transportation industry.Urban traffic congestion not only affects the development of society,but also becomes a threat for the aging bridges which are defective in the aspect of bearing capacity.Thus,it is urgent for the relevant research.Therefore,this paper is based on the contradiction between urban traffic congestion and bridge aging in China.This research is mainly devided into the following three parts:(1)With the application of WIM system,Data of the vehicle load information collected continuously for 7 days(168 hours)in urban roads of Guangdong Province were used to calculate the types of vehicles during peak traffic hours.With the help of MATLAB software,the axle loads of the corresponding models are fitted with various distribution parameters,and the optimal fitting distribution types are obtained respectively.The axle loads are represented by the values corresponding to 0.95 fractions.At the same time,the vehicle lengths and axle lengths of the corresponding models are obtained by weighted average method and the vehicle load spectrum of urban roads in Guangdong Province is verified.Secondly,by referring to the relevant specifications and documents,and with the actual data five classes of workshop spacing are set up to obtain the load model of urban bridge fleet under congestion conditions.(2)In this paper,an old single-pylon single-side cable-stayed slab bridge in urban roads of Guangdong Province is taken as the research object,and the MIDAS/Civil finite element software is used to establish the model of the bridge.The load effect of the bridge under the vehicle-20 design load is calculated and compared with the load effect produced by the vehicle fleet load model under different congestion conditions to evaluate the actual bearing capacity of the bridge under the current vehicle congestion conditions,so as to ensure the regular sercice of the bridge in the future.(3)The comprehensive safety of bridges lied to not only the support of structural bearing capacity,but also the support of structural fatigue resistance.The premise of structural fatigue analysis is to establish the corresponding fatigue vehicle model.Based on the actual traffic load data of urban roads in Guangdong Province,theload spectrum of typical fatigue vehicles is established.According to the principle of equivalent fatigue damage,the practical simplified load spectrum of fatigue vehicles is obtained.Finally,according to the cumulative damage criterion of Miner,and with the calculation of the contribution rate of fatigue cumulative damage caused by each fatigue vehicle,a standard fatigue vehicle model for urban road bridges in Guangdong Province is proposed,which covers the void of the research of the standard fatigue vehicle model for urban road bridges in China.In addition,the fatigue damage effects of the standard fatigue vehicle models in diffrent specifications are compared.It shows that the specific variables of different vehicle models should be considered in the design of bridges.