Experimental And Theoretical Research Of Concrete Structure With Specially-Shaped Columns Reinforced By Fiber Under Cycilc Loading

In recent years reinforced concrete (RC) frame structure with specially-shaped columns has received quite extensive application in China because of its good architectural functions. Scholars have done much experiment research and theory analysis to components, beam-column joints and RC frames with specially-shaped columns, with lots of achievements being made. But experiment analysis show that special sections of the columns in this structure, have made the joints of beam and columns and the column legs in the bottom story weaker than those of the rectangular column structure, and it is easily destructive and couldn't meet the seismic demand, which limit the story height and using area of the structure with specially-shaped columns. How to improve the seismic behavior of the weak part like the column legs in the bottom story and the beam-column joints, so as to enhance the story height and using area of the structure with specially-shaped columns become a key point for research of specially-shaped columns. In this paper author use the fiber to reinforce the weak part of the structure with specially-shaped columns, and through the contrast experiment and theory analysis about joints and frames reinforced by polypropylene fiber with joints and frames un-reinforced, to achieve the methods that improve the seismic behavior of the structure with specially-shaped columns.Based on the contrast experiment that about the frame with specially-shaped columns reinforced by polypropylene fiber in the joints and the column legs of the first two stories and the frame un-reinforced, the exterior joint reinforce by fiber in the core zone and the exterior joint un-reinforced, the middle joint reinforce by fiber in the core area and the middle joint un-reinforced. Compare the seismic behavior result of the two frames, the two exterior joints and the two middle joints. It is shown that adding polypropylene fiber in the joint core zone could improve the damage characteristics of the joints with specially-shaped columns significant, enhance the cracking load of the joint core zone, reduce the number and width of the cracks in joint core zone, enhance the carrying shear capacity, the reinforced effect of frame with specially-shaped columns reinforced by fiber is more obvious, it could improve the damage characteristics and enhance the carrying capacity in greater extent. This paper offers a reliable experiment basis for the polypropylene fiber reinforcing the seismic behavior of the structure with specially-shaped columns. This paper briefly introduces the shear mechanism of the beam-column joint with specially-shaped columns according to the shear mechanism of the rectangular column joint, and analyze the carrying shear capacity of the frame and joints with specially-shaped columns experimented in this paper, it proved the method is viable again that fiber reinforces the joint with specially-shaped columns. At the same time, the nonlinear finite element analysis about exterior joint and middle joint with specially-shaped columns are achieved based on FEA software ANSYS, the numerical results computed by ANSYS generally agree with the experimental results, and the FEA analysis prove that the shear in the joint core zone is delivered based on oblique bar mechanism...