Performance Of Rigid Composite Joints Under Combination Of Hogging Moment And Tensional Force

Composite beams are widely used in high-rise steel structures and steel-concrete composite structures. Compared with steel beams, it has the advantages, such as higher load-carrying capacity, higher stiffness, less height. The connections between composite beams and columns are seen as composite joints. As high-rise buildings are widely used, progressive collapse will lead to huge economic loss and evil social influence for high-rise buildings. Since the performance of progressive collapse resistance of structures and design methods have drawn great attention for engineers. If a key column fails, the loads on superstructures cannot be transferred by this failed column and the internal force is redistributed by the catenary action of joint to prevent the progressive collapse of structure. The joint is under the state of bending moment combined with tensional force which would affect the moment-resistance ability and ductility of joints. This paper presents the experimental and theoretical study on composite joints under the state of hogging moment and tensional force. The main contents are as follows:(1) The tests of rigid composite joints are carried out in order to study its mechanical properties under hogging moment combined with tensional force. The stiffnesses, load-carrying capacities, experimental phenomena and the stress states of concrete panels and steel beams under different loading steps were studied.(2) The finite element software ABAQUS is adopted to develop the three-dimension model of composite joints. The accuracy of analysis results are validated by comparing with experimental results. After this, the effects of parameters, such as reinforcement ratio, moment level, rebar strength, height of the slab, etc, on the capacity of the joint under the state of bending moment combined with tensional force are investigated.(3) Based on the experimental and analytical results, a design formula on connection load-carrying capacity under the state of hogging moment combined with tensional force are derived by"Force Balance Method". The accuracy of the formula is validated by comparing with the analysis results.