| Expressway,as one of the main transportation modes,has the advantages of quick and convenient,strong adaptability and high popularity,and it is an indispensable important part of the economic artery.The expressway bridge is an important node connecting each expressway.In order to improve the structural strength of bridges and reduce their own weight,highway bridges are generally steel bridges.Welding is the most basic and most commonly used connection method in the construction of steel bridges.The quality of welding directly affects the carrying capacity and service life of expressway steel bridges.Due to the severe temperature changes in the welding process,welding defects such as cracks and pits are prone to occur at the welding seam,and welding residual stress is unavoidable.As the service life of highway bridges increases,the bearing capacity of bridges will gradually decrease.At the same time,the residual stress caused by welding is coupled with the external load on the entire steel bridge,which affects the overall structural reliability of the steel bridge.This paper takes a steel bridge of a highway as a research object,calculates the stress distribution state of the overall structure of the steel bridge with the help of finite elements,numerically simulates the welding process,and uses the reliability analysis method to analyze the structural reliability of the steel bridge when considering the welding residual stress It provides a theoretical basis for regular maintenance of steel bridges.The main research contents of this article are as follows:(1)Create a three-dimensional model in the three-dimensional drawing software according to the engineering overview,and simplify the bridge structure at the same time.According to the current steel bridge design manual,analyze the effects of the steel bridge,calculate the weight and lane load of the steel bridge.In the analysis,the path of the secondary outer girder of the steel bridge is defined,and the stress value is extracted and compared with the steel strength of the bridge.(2)Using the finite element software ANSYS,a butt weld model was created,and the mechanical properties and welding parameters of the st eel plate base material at different temperatures were defined.With the help of the APDL language,the numerical simulation of the butt weld was completed using the life and death unit,and the welding process was obtained.The contour distribution map of the heat source center and its vicinity;change the element type,re-apply the temperature at the end of the analysis as a load to the weld position,and obtain the distribution of the welding residual stress state after the calculation is completed.(3)Through the stress-strength interference theory,the stress value under the limit conditions and the welding residual stress are coupled,and the steel bridge structure material is analyzed to obtain the steel with different reliability under different reliability,with and without residual stress and residual stress relaxation.The safety factor of the bridge structure,analyze the influence of welding residual stress on the steel bridge structure.(4)Based on the Goodman fatigue curve,the measured stres s spectra of Ganjiang Bridge and Shanghai Baidu Bridge were quoted,and the welding fatigue stress was considered,and the structural fatigue analysis of the welded steel bridge was carried out.The stress values at different positions of the main beam of the steel bridge are compared with the Goodman fatigue curve,and it is conservatively estimated whether the steel bridge meets the design requirements of infinite life. |
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