Study On Two Basic Problems Of RC Flexural Member Strengthened With CFRP

Firstly, in this paper, researching status of reinforced concrete structure strengthened with CFRP is introduced and their advantages and disadvantages is analyzed; Based on it, method is brought forwards, which includes using ANSYS in FEM analysis the structures . Secondly, the paper analyze the interfacial shear stress distribution rule through setting up and analyzing finite element models of RC beams in bending or in shear strengthened with CFS; the efficiency for CFRP used to strengthen the moment capacity of bending section is also studied. Finally, some conclusions have been made.1. When FRP is used to strengthen the moment capacity of bending section, the interfacial shear stress at the CFS end is according to the equivalent law of shearing stress which equal to zero at the end of CFS. Peak value of interfacial shear stress will appear near the end of CFS, the space between peak value and CFS end is about the size of adhesive. The cause engendering peak value of shear stress is the opposite strain direction between basal concrete and CFS at the end of CFS which cause difference deformation. Zone of adhesive near the CFS end isn't according to linear strain assumption, the range of the zone is about 50~70mm from the CFS end.2. When FRP is used to strengthen the moment capacity of bending section, the shear stress will become larger when bonding length become less; when the adhesive thickness become less; when the CFS thickness become larger. The different kinds of loads and support will influence the interfacial shear stress. The shear stress will become larger near intermediate cracks and change direction when intermediate cracks appear. The distribution rule of shear stress and CFS strain near intermediate cracks will change when Young's modulus of adhesive change.3. When FRP is used to strengthen the moment capacity of bending section, longitudinal bars'characteristic ratio of the section is of the most influence over the efficiency for CFRP to enhance the bending section, the initial moment is of an unfavorable but not serious effect for CFRP strain development. To improve the strengthening effect, it is necessary to take into account the advantage of compression steel and compression flange.4. When FRP is used to strengthen the tilt section's shear bearing capacity, The value of shear stress is maximum and the direction is changed near Shear diagonal crack.