Earthquake Resistant Behavior Study On The Special-Shaped Columns Joints Of High-Strength R.C. Frame

In this paper, high-strength R.C. beam-column knee joints of the intermediate story in special-shaped columns frame were tested under low reversed cyclic loading, The deformation characteristics and transfer mechanism were probed, which possessed important theoretical and engineering purposes.At first, the importance of the special-shaped columns joints and transfer mechanism and factors affecting seismic behavior of beam-column knee joints were generalized. Then, four beam-column knee joints of the intermediate story in high-strength R.C. special-shaped columns frame were tested under low reversed cyclic loading. The following problems have been analyzed: failure form of joints, hysteretic behavior and the influence factors of the strengths of anti-shear and so on. According to the different aims, the papers research the anti-shear performance reflections of the axis-pressed ratio, the reinforcement ratio per unit volume and fiber reinforced concrete. In addition, the seismic behavior of L-shaped joints was analyzed, including joints cracking resistance and ductility. Through the experiment, based on measurement of load-displacement of beam end and strains in the joint core and beam head in initial crack stage, yielding stage extremity and ultimate stage, the earthquake-resistant characteristics such as dissipation of energy, stiffness, crack and ductility of each member were analyzed. On this basis, the joint core shear on main stages was calculated.Through experiment analysis, the curvature ductility factor of beam was gained and the structure ductility of high-strength R.C. special-shaped columns frame was also analyzed. Then, the strength of anti-shear in initial crack stage was researched and revised calculation formula of joint shear strength. The experiment analysis indicate that the calculation formula of anti-shear capability of joints in Technical Specification For Concrete Structures With Specially Shaped Column does not completely apply to the joints of high-strength R.C. special-shaped columns frame. The influence of axis-pressed ratio in this formula does not accord with the characteristics of the joints of high-strength R.C. special-shaped columns. Based on the experiment, the influence of axis-pressed ratio in the joints of high-strength R.C. is analyzed. Finally, the calculation formula of anti-shear capability, of the joints high-strength R.C. special-shaped columns frame was put forward to, which may act as foundation for further research.The article analyses joints by finite element software—ANSYS, the purpose is to study the formation mechanism of crack,the stess state of joint as well as the influence of axial compression ratio on the carrying capacity of joint. Through non-linear analysis, the carrying capacity variation laws of high-strength R.C. special-shaped column joint were gained under different axial compression ratio. The validity of joint capacity formula was also tested.