Life Cycle Evaluation And Fatigue Study Of Small And Medium Span Composite Bridges

Because Chinese steel production has maintained as the world's first for the past 17 years and The Belt and Road policy has been implemted,bridges need to use steel as the main material.At present,China is lagging behind in the research and application of the standardized construction of the composite structure bridge,and because of the lag of the basic theory and the lack of the corresponding standard,even if the combination structure is selected as the recommended scheme,the economic cost is likely to be higher than the normal concrete structure bridge,and the economic advantage of the composite structure is lost.Therefore,it is necessary to make a standardized design for the steel-concrete composite bridge,and make it have a good economy.At the same time,the static and dynamic characteristics and the fatigue life of the structure are studied in order to provide practical results for the research units and management units.This paper focuses on the economic and fatigue life of small-and-medium span steel reinforced composite structure bridges.The main research work is as follows:Firstly,the structure of small-and-medium span composite bridges in mountain area are summed up and introduced.At the same time,according to the ABC bridge construction method,the standardized design suitable for small-and-medium span composite bridge in mountain area is obtained by the finite element analysis software.Secondly,using life cycle concept,the recessive economic cost is calculated simultaneously with the construction period,the operation period and the recovery cost,and the economic evaluation formula of the small and medium span bridge in the mountain area is put forward in combination with the industrial evaluation formula and the life curve of the Pareto,and the economic evaluation of the standardized structure obtained is the most suitable structural form.Thirdly,the data of the measured traffic load data are processed,and the four phase method is used to estimate the traffic growth.Then,the parameters of the model,weight and speed of the random traffic flow samples generated by Monte Carlo method are analyzed.Then,under the condition of vehicle-bridge coupling,the fatigue stress of the structure is carried out.Finally,the finite element modeling of the recommended standardized structure is carried out,the linear static and dynamic analysis is carried out,and then the stress course is obtained by loading the random traffic.Then the stress amplitude spectrum is obtained by the rain flow counting method.Then the fatigue life of the bridge is calculated according to the traditional S-N curve and the modified S-N curve and the fatigue damage criterion.