| The steel concrete composite structure is a new type of structure,which combines the advantages of steel and concrete,and has been widely used in Bridge Engineering in recent years.However,compared with the bridge performance under static load,the research on the fatigue performance of composite beams is not deep enough,which has been paid more attention by scholars at home and abroad.With the deepening of industrialization,different structural forms of composite beams and different working environments put forward higher requirements for the fatigue performance of composite beams.This paper mainly completes the following work content.(1)In this study,four specimens of steel-composite beams were designed and made,and the fatigue properties of composite beams were studied in depth.Among them,on a piece of the uniform type stud arrangement specimens of steel-site casting composite beams has been bended moment static load test were carried out to determine fatigue load,the fatigue tests of three composite beams were carried out(two steel cast-in-place composite beams with uniform stud arrangement and one steel precast composite beam with cluster stud arrangement).At the same time,in order to simulate the chlorine corrosion factors in the actual working environment,accelerated corrosion tests were carried out on all specimens in this paper.The final test shows that there is no significant difference in fatigue performance and fatigue life between the two types of steelcomposite beams.The conclusion lays a research foundation for the application of the steel-precast concrete composite beam with cluster stud arrangement in practical engineering.Especially in the alpine-high altitude area,the construction method of precast assembly can not only speed up the construction progress but also ensure the construction quality.(2)Based on the non-continuous shear transfer model,the static load performance and fatigue performance of the two types of structures were analyzed.The analysis shows that the slip distribution law of the two types of structures under static load is not consistent,and there is no obvious difference in the structural stiffness during normal operation.Due to the fact that steel is more sensitive to fatigue load than concrete under fatigue load,the bending moment in the middle span of steel beam decreases gradually with the fatigue cycle after considering the fatigue degradation of material properties.The relative slip of the two types of structures under fatigue load is calculated,and the results show that the relative slip of the cluster stud arrangement and the uniform stud arrangement have little difference,which indicates that the former can meet the need of shear strength of the joint surface.In order to verify the accuracy of the non-continuous shear transfer model,the calculated values are compared with the experimental values,and the two are in good agreement.(3)Based on the finite element software ABAQUS and fatigue analysis software FESAFE,the fatigue life of the composite beam was simulated and analyzed considering the factors of initial defects,and the final simulation results were in good agreement with the actual fatigue life.According to the fatigue test life,the final fatigue life of the composite beam has no obvious relationship with the arrangement of studs,but has a great relationship with the initial defects.Therefore,when fatigue analysis software is used to simulate fatigue life,material defect should be introduced as a necessary factor,so that the final fatigue life simulation results can have a better coincidence degree. |
