Research On The Uplift Performance Of Headed Studs In Composite Structure

The steel-concrete composite structures have been developled rapidly in recent years, due to its outstanding behavior on making best use of materials, construction convenience and economic benefits. Headed-studs, the most common form of shear connector, are used to transfer shear loads between steel and concrete, which makes it a key point of research on composite structure. Most of the exsiting research was focoused on the shear behavior of studs, in this thesis research on uplift performance was discussed. The main research work in the thesis is as follows:(1) Investigation and summary work on the existingresearch of stud uplift performance. The research method and technical route of this thesis was proposed.(2) Experimental study on uplift performance of headed-studs for concrete, series of pull-out tests were conducted, using the self-balanced loading system,to study the factors that might influence the uplift performance, and two kinds of failure modes, i.e., pullout failure of the concrete and failure of stud’s shank, were observed. Based on the test results, the influence of stud’s embedment length, edge effect, stud spacing and rebar reinforcement on uplift capacity of cast-in-place headed-stud was discussed.(3) The load transfer path was obtained according to the observation of experimental phenomena. The uplift bearing capacity for headed-stud was derived based on hypothesis of rigid-plastic model and double shear three parameter criterion.(4) Numerical models were established by finite element analysis via Abaqus. Compared with the test results, the reliability and accuracy of the finite element models were verified. Based on the finite element model, parameter study was conducted, the influence of stud diameter, stud length, stud strength and concrete strength on the uplift bearing capacity was analyzed.(5) Focusing on the uplift restricted-slip free studs that used to improve the mechanical performance of continuous composite beams on negative moment region, seven pull-out tests were conducted,two kinds of failure modes, i.e., punching shear failure of concrete and failure of stud’s shank, were observed. Based on the test results, the relationship between the uplift performance and the size of studs was discussed. Furthermore, design formula for ultimate uplift capacity and construction details were proposed. The results indicate that the uplift restricted-slip free studs own excellent uplift performance, and the main factor that influence the uplift performance is the size of studs.Conclusions of the reseach results and forecast of the future work were recorded at the end of the thesis.