The Research On The Seismic Behavior Of R.C Space Joints Strengthened By Carbon Fiber Reinforced Plastic

Reinforced concrete beam-column Joints are important elements in the frame structures. It connects the beam and column, transverses and distributes the inertial forces, also it makes the structure's deformation compactable in components. The earthquakes happened in the world have proved that the structure will be severe destroyed when the joints damaged. Earthquakes are often happens in our country, so as to reduce the losses of earthquakes, it needs to repair and retrofit the current buildings, especially retrofitting the frame joints. So to do some research about the frame joints' retrofitting is necessary.Because the joints locate in the crossing of the beams and columns, the details and forces acting on the joints are very complicated, so it is hard to repair and retrofit these inadequate performance joints. From the previous research level in domestic and abroad, about this new retrofitting technique's research mainly focus on the simple elements' repaired, such as the beams' and columns' moments and shear resistance strengthening. About the beam-column joints retrofitting there is little study, especially on the joints having slabs and lateral beams. So such technique is a significant one which deserves further investigation.In this paper, the main research objectives are the space middle beam-column-slab-lateral beam subassemblies which are reinforced with low ratio transverse reinforcement. Using different CFRP paste styles and the core's CFRP amount as variance parameter, the shear resistance mechanism of joints and the rational retrofitting styles are researched by the general program ANSYS9.0.The following is this paper's main work:First, summaries the research leaves of the CFRP, the shear resistance mechanism and the damages of the earthquakes about the reinforced concrete joints in domestic and abroad. Get the resultthat using the CFRP to retrofitting joints is an effective and practicable method. Because the research leave at present is low, so the performances of the strengthened joints with CFRP need to do some study in a deep-going way.Second, introduce the theory about the nonlinear finite element analysis of the reinforced concrete structures;do some initial research on the bond-slip between concrete and rebar, the stripping mechanism between concrete and CFRP.Third, introduce the process of the concrete structure nonlinear finite elements analysis about the program ANSYS9.0.Using it to do a full-range nonlinear analysis about a testing joint under monotonic load. The numerical result and the experimental result are compared. It is found that using program ANSYS9.0 to simulate the test about joints strengthened with CFRP is practicable.Forth, based on six joints' numerical results, the joints' cracking and failure process are gained. Analyze the different strengthened effect of the different retrofitting style joints in damage mode, carrying capacity, stiffness, ductility and other fields.Fifth, analyze the performance of the strengthened mechanism of the frame structure joints by CFRP. Based on the calculated formula of joints' shear resistance capacity in current national regulation, bring forward a coefficient rjf to regard the core concrete's strength hardening and the area increase of inclined strut. A simplified formula to calculate t]f is put forward.Sixth, discuss the appropriate conditions and retrofitting detailing measures about the using CFRP to strengthen R.C frame structure joints. Summarize the problems exiting in the numerical calculate on the R.C frame joints.