Study Of Shear Bearing Capacity For High Performance Reinforced Concrete Beam-Column Joints

In this thesis, the research status and the failure modes of Reinforced Concretebeam-column joints are addressed, and the theoretical feasibility of a quantitative analysisof failure modes is presented. The author found that the constrain mechanism andcombination block mechanism were the theoretical extension of diagonal strut-trussmechanism in the loading process. In the end of the loading process, with the degenerationof the diagonal strut-truss mechanism, the existing of constrain mechanism andcombination block mechanism made the beam-column joints keep a big part of bearingcapacity.The failure modes of the beam-column joints are predicted by the simulation of joints withHRB500E high performance steel bars using finite element package ANSYS. Beambending failure occurs in JD2and JD3, while both beam bending failure and shear failureoccurs in JD1simultaneously. In order to study the influence of axial compressive ratio,shear-compression ratio and stirrup ratio in the core area of joints on the shear bearingcapacity for high performance reinforced concrete beam-column joints, some specimenshave been expanded in this paper. The numerical results of the existing and expandedjoints shows that, under the condition of low shear-compression ratio, the stiffness andshear capacity of the joints can be improved with the increase of the axial compressionratio and the stirrups in the core area of joints.Although shear-compression ratio has no effect on the shear bearing capacity ofbeam-column joints, it is the major factor, associated with stirrups in the core area of joins,that affects failure modes of joints. Under the condition of low shear-compression ratio,beam bending failure will happen; under high shear-compression ratio, with the increaseof stirrup ratio in the core area of joints, diagonal tension failure, shear compressionfailure and diagonal compression failure will happen sequentially in the core area.