Confinement effect of CFRP and steel ties in circular RC columns 30 MPa concrete strength

In today\u27s technology, the methods of confinement are now being used in retrofitting and rehabilitating concrete structures. Through extensive research, Carbon Fiber Reinforced Polymers (CFRP) is slowly being introduced in the construction industry. The used of CFRP is a good material for confining the concrete structures, in addition, its properties also shows remarkable performance due to its resistance to corrosion, flexibility and it is lightweight. Circular RC columns with 180 mm diameter and height of 500 mm were wrapped with CFRP and were then tested under uniaxial compressive loading until failure. The fibers sheets of the CFRP were oriented 90() with respect to the longitudinal axis in order to provide lateral reinforcement to the RC column. This paper investigated the axial load, axial strain and the lateral strain of the wrapped RC columns and compared it with the plain RC columns. The most significant increase in strength was seen for the specimens wrapped with 2 layers of CFRP. For specimens having no steel ties the increase in strength is 47%, while the specimens with the 40 mm steel tie spacing achieved an increase of 72% in the ultimate compressive strength. As a result, the increase in compressive strength for a typical reinforced concrete column was greatest when wrapped with 2 layers of CFRP because it increases the load bearing capacity of the column. The research had shown that the use of CFRP increases the ductility of the column as well as the physical properties like aesthetics. Thus, minimizing the amount of maintenance required