Nonlinear Finite Element Analysis On The Shear Strength Of T-Shaped Column Joints Of Reinforced Concrete Frame Structure

Currently, there are not enough research and testing on the special-shaped column joints. Because special-shaped column joints are weaker than rectangle joints, Earthquake disaster may be more serious .19 T-shaped joints under single loads are analyzed by useing the finite procedure ANSYS software by nonlinear FEM. Models are divided into five groups, each analyzed anti-blending stiffness ratio h_b / h_c of beam-column , joint's wing-board width b_f , axial-pressed ratio μ_N ,. concrete strength grade and hoop steel ratio and so on affected by the endure mechanisms, internal force distribution, the cracks development of joints and anti-shear strength of jointS.The researches of Nonlinear analysis indicate that: (1) The endure mechanism of T-shaped joints under lower axial-pressed ratio is liable to the more inclined press-pole mechanism than one of rectangle joints . The joints' crack shape appears reverse "V" shape but not the rectangle joints' "X" shape under the cyclic loads, opening and extending towards wing-board side;(2) Anti-shear strength of joints affected by the anti-blending stiffness ratio h_b / h_cbeam-column. (3) Wing' contribution to the capacity of anti-shear of joints lag, the scope of wing-board width has a certain limit. (4) Appropriatly raising of axial-pressed ratio benefits to anti-shear strength of joints, but in higher axial-pressed ratio reduced. (5) The strength of concrete can increase the early cracked load, and to some extent enhance joint carrying capacity. (6) The presence of hoop steel can effectively improve damage load of joint, but for the early cracked load is not obvious 。Finally, a few improvements are suggested about the caculating formula in the national existing Technical specifications of RC structure with columns of irregular shaped sections(draft).