Study On Fatigue Load Spectrum Of Bridge In Plateau Mountainous Area

As an important infrastructure in the highway,bridges play an important role in transportation.Yunnan province is located in the plateau mountainous areas where water and mineral resources are rich.There in much vehicles which is used for transporting the large hydropower facilities and mineral raw materials that lead to a serious phenomenon of vehicles to over-limited and over-load.When the movement of these over-limited and over-load vehicles along the bridge is cyclic,It will cause serious fatigue damage for the bridge,once the fatigue damage accumulate to a particular point,bridge damage or even collapse could happen,that eventually lead to individual and social wealth and the state-owned assets with immeasurable losses.Therefore,in order to ensure the safe operation of the bridge and to provide technical basis for the relevant departments,this paper carried out the research on influence of plateau mountain highway bridge fatigue load spectrum based on random overload,the main work is as follows(1)Through investigating the vehicle information of representative highway in Yunnan province,and by using clustering analysis method,the paper makes a classification of the vehicle data.after that,by threshold processing,the vehicle data can be divided into two types,ordinary traffic and overloaded vehicles,and the paper proceed statistical analysis to determine the statistical characteristics and distribution parameters.(2)Based on the above statistical analysis results,a stochastic traffic flow program is developed based on the Monte Carlo method through the computer development environment Visual Fortran 6 and Fortran language,which can simulate stochastic traffic conveniently.(3)This paper aimed the fatigue problem of concrete reinforced,with the selection of a main highway bridge in Yunnan province.The stochastic traffic flow is loaded on the influence line which is calculated with finite element software of the cross bridge,and then analyse the fatigue response that based on the highway bridges in plateau mountainous area.Then,the "reservoir method" is used to count the load amplitude and the number of cycles in the process of the internal force response of the bridge,and the corresponding fatigue load spectrum is got.(4)Based on linear fatigue damage accumulation theory and the comparison and analysis of the fatigue damage and fatigue life of the bridge under the overload random flow and the common random traffic load,this paper analyzes the influence of fatigue load spectrum that based on the highway bridges in plateau mountainous area.(5)Based on the above research,the load frequency value spectrum and standard fatigue car model are developed for the highway bridge in Yunnan province,and based on the standard fatigue car for overloading and vehicle speed on the bridge damage degree of influence,this paper provides overload coefficient and its correction coefficient at different speeds.