Enhancing the Effectiveness of Strengthening RC columns with CFRP sheets

The column is the most important structural element were strengthening of columns became a demanding issue. In this paper, the effectiveness of strengthening reinforced concrete (R.C) columns with carbon fiber reinforced polymers (CFRP) wraps has been improved by increasing the contact area between the column’s surface area and CFRP. A new strengthening technique was hired for the purpose of enhancing the efficiency of CFRP jackets in improving the load capacity of R.C columns, especially columns with rectangular sections. The method is based on increasing the contact area between the CFRP jacket and the column's surface area. This was done by adjusting the profile of the col's cross-section to almost ellipsoidal. The experimental program in this research includes testing 13 columns to include all test parameters, the shape of the cross-section, and the cross-section profile. The results include axial stresses and corresponding axial strains, and lateral strains at the mid-height and quarter height of tested specimens. And also, the cracking load and maximum load with crack patterns are determined. The comparison involved the study of the effect of the traditional CFRP jacket wrapping of R.C columns with square, and rectangular sections and the newly developed strengthening technique. A theoretical study was also conducted. Where the capacity of the square and rectangular confined columns with different radius of curvature, R, of the ellipsoidal profile is determined by the predicted and design equations. The study revealed that the strengthening technique is expected to effectively enhance the efficiency of the CFRP strengthening technique, especially for columns with square and rectangular sections as the area of the well-known dead zone of these columns is reduced using the proposed technique. Also, the results proved that the efficiency of strengthening tested columns by CFRP jacket has been enhanced using the strengthening technique by about 80% of original RC columns, which exceeds the traditional method (Jacket) CFRP wrap by 60%.