| Steel-concrete composite girder bridge is convenient in construction,cheap in cost and superior in performance.It is widely used in the current bridge engineering application.The shear nails are the key components connecting steel girder and concrete bridge deck,and their mechanical performance directly affects the structural stability of the whole bridge.When the arrangement of shear nails is too dense,the shear stiffness and shear bearing capacity of shear nails will be reduced,which will affect the overall performance of steelcomposite girder bridge.Some scholars put forward the use of large diameter in shear studs group of shear studs instead of the conventional shear pin diameter,but most of the existing study of shear studs for conventional shear pin diameter,large diameter of the shear pin research is still in the preliminary stage,the domestic specification did not formulate relevant regulations to shear studs group,studies on the influence factors of shear pin group performance is not yet mature,It is still doubtful whether large diameter shear screws can effectively alleviate the reduction phenomenon of shear screws group.Therefore,it is of great significance to study the mechanical properties of large diameter shear studs and shear studs group for the structural design of steel-concrete composite girder bridges.In this paper,the rationality of finite element software modeling method was verified through the introduction test in literature [20] and literature [44] simulated by ABAQUS software,and on this basis,the mechanical properties of large diameter shear screws and shear screws group were studied.The main contents are as follows:(1)The influences of the diameter,length,strength and concrete strength of shear nails on the shear bearing capacity of a single shear nail are studied.The effect of the length of shear nails on the shear bearing capacity of concrete strength is very small and almost negligible.The diameter of the shear nail has a significant effect on the shear bearing capacity,and the diameter of the shear nail has the greatest effect on the shear bearing capacity.At the same time,the mechanical properties of 22 mm diameter shear nails and30 mm diameter shear nails under various influencing factors are compared and analyzed.It can be found that the two kinds of shear nails with different diameters have similar changes with various factors,and the 30 mm diameter shear nails have better performance and higher shear bearing capacity under the same conditions.(2)A push test model of shear nails group was established to compare the failure modes and calculated results of single shear nails and shear nails group.The results show that the root of the shear nails is broken in both the push test of the shear nail group and single shear nail,and the shear bearing capacity of the group nails is reduced by 22% compared with that of the single nail,and the shear stiffness values calculated by various formulas are reduced by more than 20% compared with that of the single nail.(3)The influence of shear nail length,diameter,strength and concrete strength on shear nail group was analyzed and compared with single shear nail.With the increase of the length of the shear nails,the shear bearing capacity and shear stiffness of the shear nails in the shear nails group decrease first and then increase,and the shear nails group with the length of180 mm has the best performance.With the increase of the diameter of shear nails,the strength of shear nails and the strength of concrete,the reduction degree of shear bearing capacity and shear stiffness of the group of nails decreases gradually,among which the diameter of shear nails has the greatest influence.The reduction degree of shear bearing capacity of the group of shear nails with a diameter of 30 mm is only 12.4% compared with that of a single shear nail with a diameter of 30 mm.Using large diameter shear nails can greatly reduce the reduction of shear bearing capacity caused by the group effect of nails.(4)The effect of the number of shear nail columns,rows,transverse and longitudinal spacing on the shear nail group is analyzed.The reduction degree increases with the increase of the number of shear nail columns and rows.With the decrease of transverse and longitudinal spacing,the reduction degree increases gradually.It can be found that the denser the arrangement of shear screws,the more obvious the reduction phenomenon of shear screws group,changing the row number and longitudinal spacing of shear screws has a greater impact on the performance of the shear screws group,that is,along the direction of the shear screws group,the arrangement of shear screws has a greater impact on the performance of the shear screws group.Figure [51] table [25] reference [66]... |
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