Experimental Study On The Ultimate Shear Capacity Of Grouped Stud Connectors In Continuous Composite Steel-Concrete Girder Bridge

The concrete slab in the negative moment regions of the continuous composite steel-concrete bridge is in tesion, the longitudinal prestress is used to prevent the concrete slab from cracking. The wire tendons are stressed after that the slab is attached to the steel girder, but corresponding stresses in the steelwork is large. In order to introduce the prestress only into concrete slab, the stud shear connectors are weld in groups through large holes in the slab, the non-shrink mortar is used as filler after completion of the prestressing. The ZouQu Bridge in JiangSu province has used this construction method.The push-out tests are carried out to study the behavior of the connectors in 7 specimens: 4 of them are used to study the behavior of single stud, while others are used to study the behavior of studs in group. The mechanical characteristics of the studs in group are investigated and are compared with sigle stud conector. The test results showed that the shear strength and shear stiffness of the studs in group are lower than that of the sigle stud.The shear stiffness of stud shear connectors in cmposite beams is derived from the analysis of 34 push-out tests. 10 approximate formulas are attempted to describe the load-slip relationship. The relationships between the stud shear stiffness and the variables such as stud positions, diameters of stud, prestressing on the concrete and effect of grouped studs are discussed.The effect of slip on the mechanical behavior of simply supported composite steel-concrete beams is analysised. The analytical expressions of interface slip, deformation and curvature are proposed. The stress distribution of the composite beam is obtained.In order to analyse the mechanical behaviors of continuous composite steel-concrete beam, the finite-element model is proposed, the concrete slab and steel girder are modeled with 2 separate beam elements, and the shear connectors are modeled with spring elements. The shear stiffnesses of the shear connectors are obtained from the push-out tests. The results of the analysis show that the effect of...