Strengthened By Cfrp Damage Of Reinforced Concrete Frames Under Vertical Loads Pilot Study

The function of structure will be weakened gradually under the both action of natural environment and using environment chronically, which is an irreversible objective law. If the law and extent of this kind of damage can be assessed scientifically and the effective measures can be taken timely, the process of structure damaging will be slowed, and in turn the usage life of the structure will be extended. From 1970's, the reinforcing concrete structure by CFRP (Carbon Fiber Reinforced Polymer) have been studied in china, and many achievements and abundant data have been accumulated through experiments on join of beam, column, plate, joint and conformation etc. But the aim of above researches is the behavior of reinforcing individual component such as simply supported beam, overhanging beam and column by CFRP, and there was little researches on the beam/column of RC (Reinforced Concrete) framework as a whole. The structure problems in the practical projects were mostly about the whole framework beam, column-cracking under overload and the damage need to be reinforced. Therefore, in this paper the reinforcement design and experiments of damaged whole framework structure of RC would be studied.The experimental study of two kinds of damaged concrete framework structure components that designed by reduced scale model of 1:3 have been made in this paper. Firstly, The reinforcement test sample has carried on the structure examination and the internal force and the bearing capacity analysis. Secondly, the CFRP reinforce scheme of reinforcement test sample and the vertical load experiment plan was designed. Finally, an experiment on reinforced components under vertical load action was made. In this paper the force-bearing status of the components under vertical load after it was reinforced is analyzed and the influence on the whole performance of reinforced framework structure by the number of CFRP reinforcing layers, cracking factors and the damage of original components were studied. The change of load capacity and rigidity of framework beam and column after they were reinforced by CFRP are also analyzed. Based on the experiment, the cracks and deflection and damaging of beam and column on normal use stage and ultimate bearing capacity state are analyzed after the structure components were reinforced by CFRP. The beam load-deflection curve, load-CFRP strain curve of beam and column, beam load-reinforcing steel bar strain curve etc are portrayed and the influence of CFRP reinforcing on the cracking and load capacity of reinforced framework structure are also analyzed.Through analysis, for the large crack of damaged concrete structure, glue-pouring and paste U-form hoop with small distance can effectively prevent the extent of crack. By paste CFRP at the bottom of beam and felt anchor fixing, not only the bend of reinforcing steel bar can effectively prevented, also the ultimate anti-bending load capacity of beam can be increased drastically. Because of the restriction of CFRP, the section anti-bending rigidity of reinforced beam will be increased. After reinforced by CFRP, the pulling force of beam bear by reinforcing steel bar and CFRP together; while the steel bar is bended, the action of CFRP will be augmented and bear the pulling force mostly.