Experimental Study Of Semi-rigid End-plate Composite Joints

The study on the behavior of semi-rigid joints in steel-concrete composite frames gets widely attention recently. A high degree of continuity can be achieved at a very low cost just providing the slab with rebar running along the column. Furthermore, stiffness and ultimate resistance can be controlled in a rather simple way by a suitable selection of steel connection detailing and amount of reinforcement. But at present, the knowledge of joint behavior, and of its influence on frame behavior, is not broad enough to allow for joint design and detailing at the required degree of reliability. Thus it is necessary to study moment resistance, rotation stiffness and rotation capacity of the joints.In this paper, six specimens on end-plate composite beam-to-column joints and two specimens on end-plate composite beam-to-column joints were designed to subject to static load. The factors of M-φ characteristics about semi-rigid composite joints, including bolts, profiled steel sheeting, beam, column, stiffen rib and reinforcement, are studied. The test results show that the semi-rigid composite joints have higher moment resistance and rotation stiffness than steel joints, and composite joints have powerful rotation and dissipation energy capability.Based on the test results, the formulas for moment resistance of semi-rigid end-plate composite joints are presented. Which adopt plastic analysis method, and take for reinforcement damage as failure criterion. The accuracy of the proposed method have been verified by the test results.The concept of adding the contribution of rebar to a bare steel connection is utilized to form the stiffness of composite semi-rigid joints under hogging moment. Upon this basis, the calculating formulas of initial rotation stiffness are presented. The calculated results show to be in good agreement with the test results.It is necessary that rotation capacity of composite joints is enough for moment distribution of composite beams. The calculating method of rotation capacity for semi-rigid composite joints is described in this paper. Comparison with test results show that, the introduced calculating model of rotation capacity for semi-rigid composite joints is rational. A finite element model is developed in this paper. In the model, the effects of slip between concrete slabs and steel beams and the behavior of semi-rigid for beam-to-column connection are considered. Taking the full advantage of the available test and researchinformation on joints, a simply two-dimensional finite element model is demonstrated. Then the M-φ characteristics about the composite joints can be utilized in the analysis of the semi-rigid composite structures consequently.