Partial strengthening of R.C square columns using CFRP

In some buildings, when quality control is poor, the upper parts of columns have a weak compressive strength, especially in floor zone. Low compressive strength for upper part of the column will lead to a reduction in bearing capacity of column. Strengthening of this part using traditional methods such as R.C jackets and steel jackets will not satisfy the architectural conditions. Also the Egyptian code for design and construction of fiber reinforced polymers prevents partial strengthening of rectangular columns with fiber laminates.This study is carried out to investigate the overall behavior of R.C square columns with poor concrete at upper part, strengthened with CFRP. The wrapped part of column was the upper part only.An experimental program was undertaken testing ten square columns 200 × 200 × 2000 mm. One of them was a control specimen and the other nine specimens were strengthened with CFRP. The main parameters studied in this research were the compressive strength of the upper part, the height of the upper poor concrete part, and the height of CFRP wrapped part of column. The experimental results including mode of failure, ultimate load, concrete strain, and fiber strains were analyzed. The main conclusion of this research was, partial strengthening of square column using CFRP can be permitted and gives good results of the column carrying capacity.