The Improving Measures Of The Shear Capacity Of The Specially Shaped Columns Joints

Reinforced concrete frame joint is always considered as the weakest region of frame structure, and usually occurred by shear failure in earthquakes.The special-shaped column frame structure is a new type of structure and there are not enough experiments and research on the joints at present, so it is necessary to take further research.Because the thickness of column web and flange is equal to beam width, and the depth-thickness ratio of special-shaped column section is large, what more there are heavily-distributed steel bars in the joint of beam and column, concrete vibrating is not easy, the special-shaped column joints are weaker than the rectangle joints.Based on the concrete smeared cracking isotropic constitutive model for concrete, a nonlinear finite element analysis programme ABAQUS is used. The cracking and crushing of concrete is simulated with stress-release method. It shows that the results of simulation is basic anastomotic with the experiment. Through calculation, the method is proved to be feasible.This paper analyzed three special-shaped column joints (L,T,+) and three joints with welded haunch under bending moment, shearing force, and axis force, obtained basic properties of these jonits, which include load transfer path before and after cracking, stress distribution, occurrence and development of cracks and final failure mode of the joint. The results testifies very well with the test through analyzing the computational results.Comparing the appended armpit joints with the normal joints in craze load, limit supporting capacity, crack distribution, the results showes that it improved its stress performance. The results can be provided design basis to the enhance shear strength for the specially shaped column frame structure.