Study On Shear Behavior Of Grouped Head Stud Shear Connectors Between Precast High-strength Concrete Slabs And Steel Beams

With the rapid development of modern construction technology,prefabricated steel and concrete composite structures are being used widely over the world due to its rapid construction,economic benefits,good durability and long-term performance of constructions.Steel-precast concrete slabs composite structures could effectively make full use of the tensile properties of steel and compressive strength of concrete,reduce the structure self-weight and improve the bridge spanning capacity.The shear connector,as a crucial element,enhances the longitudinal shear capacity and limits the separation/uplift between these two members,and ensures precast concrete decks and steel girders to work together.The mechanical properties of steel-precast concrete deck composite structure are largely determined by the shear behavior of head stud shear connectors.However,research on the shear behavior of head stud shear connectors embedded in high-strength concrete is very limited.In this paper,the shear behavior of grouped head stud shear connectors between steel beams and precast high-strength concrete decks has been investigated through the push-out tests,finite element simulations and theoretical analyses.The main tasks of this thesis are as follow:(1)Based on a comprehensive literatures review on the shear connectors,a research plan has beeb developed to analyze the shear behavior of grouped head stud shear connectors between steel beams and precast concrete decks.(2)The shear behavior of head stud shear connectors was commonly tested by the pushout tests as suggested in Eurocode 4.Twelve push-out specimens,with different stud height,stud diameter,stud arrangement,deck thickness,and the casting method of infilling concrete strength in shear pocket,were tested in this investigation.The experimental results indicated that the shear strength of head stud shear connectors was mainly affected by the stud diameter,however,the stud height,stud arrangement and deck thickness had a little effect on it.In addition,the casting method of the shear pocket almost had no influence on the shear strength of head stud shear connectors.(3)In the numerical analyses,the finite element(FE)models developed using ABAQUS were validated by comparing their results with the push-out test results.The validated FE models were used to conduct detailed numerical parametric studies in which a wide range of the parameters were used to further investigate their influences on the shear behavior of head stud shear connectors between precast concrete decks and steel beams,which included the stud height,stud diameter,stud spacing,deck thickness,infilling concrete strength and casting method of the shear pocket.The shear strength of head stud shear connectors almost linearly increased with the stud diameter and infill concrete strength.However,the stud height had little effect on the shear behavior.Increasing the stud spacing and slab thickness cloud not enhance the shear strength.The numerical results also indicated that the precast and cast-inplace method of the shear pocket had the same effect on the shear strength of head stud shear connectors.(4)The numerical results were compared with the calculated values in accordance with the current design provisions of the steel-concrete composite structures.It was observed that those specifications almost had some deviation to the shear strength of the shear connectors.Based on the experimental and FE results,a more accurate analytical equation was proposed to evaluate the shear capacity of grouped head stud shear connectors.The means of predicted/tested results for all specimens were varied from 0.972 to 1.022,which indicated the equation can predict the shear strength of grouped head stud shear connectors between steel beams and concrete slabs.