Pseudo-static Test Research Of Interior Staggered Beam-column Joints Of Reinforced Concrete Frames

With the diversification of people's esthetic sentiment to upholstery,the staggered reinforced concrete frames are used more and more widely. Specifications for staggered joint aren't contained in Code for Design of Concrete Structures GB50010-2002,so,the research on shear transfer mechanisms;seismic behavior and shear resistance of staggered joints is urgent.Experiments of six staggered beam-column joints of RC frame under slow cyclic loading are completed,among which three specimens' elevation difference of beams is one beam height and the others' is two-third of beam height,through the experiment study and the compare of their seismic behavior with ordinary joints',the following is concluded:1. Staggered joints failure is lighter than ordinary joints when the area of beam bars is same in the two types of joints.2. Sliding displacement of beam longitudinal bars in staggered joints is smaller than in ordinary joints,and the beam bar' overstrength in staggered joints is more serious than in ordinary joints when shear force is equal in the two types of joints.3. The performance of staggered joints is similar to ordinary joints',not only about the plump of hysteresis curves,energy dissipation,but also the time,the rapidity of shear resistance decrease and the degree of joints stiffness degradation. Only the displacement ductility coefficient in staggered joints is little smaller than in ordinary joints.4. Axial compressive ratio is advantageous to seismic behavior of staggered joints. It can improve joints first crashing loads,shear resistance capacity and reduce the sliding displacement of beam bars. The staggered height has some influence to joints seismic behavior,too. Generally speaking,the energy dissipation capacity of the joints with shorter staggered height is better than the ones with longer staggered height.5. The formulae that the lately issued Code for Design of Concrete Structures GB50010-2002 offered are applicable for design of staggered joints,considering joints failure not serous and the difference very little between calculative values and experimental values of staggered joints.