The Research On Fatigue Damage Of Steel-concrete Composite Structures Considering The Size Of Shear Connectors

Steel-concrete composite structure has excellent performance and simple construction,which is widely used in the process of bridge construction at present.As an important connecting component in steel-concrete composite structure,shear connectors have become a key problem to be solved urgently.In this paper,the fatigue behavior of bolts is studied by combining theoretical analysis with numerical simulation,considering the influence of structural size of shear connectors.The main contents of this paper are as follows:(1)Based on the modeling method proposed in this paper,a refined finite element model is established,which is the same as the existing experimental research,and the calculation and analysis are carried out.By comparing the results of this paper with those of the original experiment,it is found that the proposed modeling method is reasonable and has high precision,which can support the follow-up research(2)Based on the modeling method proposed in this paper,and combined with practical engineering,the ANSYS finite element model of push-out test is established,and the effect of bolt size on the bearing capacity and fatigue performance of bolt in push-out test is studied.It is found that the diameter of the bolt has a great influence on the bearing capacity and fatigue performance of the bolt in push-out test,while the change of the length of the internal bolt required by the existing specifications has a little influence on the bearing capacity and fatigue performance of the bolt.(3)Based on the real bridge,the refined ANSYS model of some beam segments is established,and the influence of the size of studs on the fatigue performance of studs in the real bridge is studied.It is found that the overall stress amplitude of the bolts in the real bridge is much smaller than that in the push-out test,and the equivalent constant stress amplitude of the bolts details is greatly affected by the diameter of the bolts,but relatively not by the length of the bolts;the equivalent constant stress amplitude of all the bolts details selected in the background bridge is less than 90 Mpa,and the fatigue life of the bolts meets the requirements and the structure is reliable.