The mechanical behavior of composite-wrapped concrete cylindrs subjected to uniaxial compression load

Recent earthquake damages have repeatedly demonstrated the vulnerabilities of older reinforced concrete columns to seismic deterioration. The use of steel and fibre-reinforced plastic (FRP) materials wraps on aged and damaged concrete structures has been recognised as an effective method to restore the load carrying capacity and extend the service life of the structures. Steel, glass and carbon fibre composites have been increasingly used to reinforce the concrete column by putting the wraps around its circumference in order to maintain its structural integrity by constraining the lateral dilation of the column when it is subjected to axial compression load. This paper presents the behaviour of the wrapped concrete cylinder with different wrapping materials and bonding dimensions using finite element (FEM) and analytical methods. The experimental results show that the deflection of the wrapped concrete cylinder in the load direction decreases with increasing the length, thickness and modulus of the wrapping sheet. However, using a longer wrapping sheet with high modulus may not benefit the structure since it creates negative hoop stress in the wrapping sheet. An analytical equation is provided to estimate the shear stress distribution of an adhesive material for different wrapping geometries. The results of the equation compare well with FEM solutions.