Creep and shrinkage effect on adhesive stresses in RC beams strengthened with composite laminates

In this paper, a closed-form solution for interfacial stresses in externally FRP plated RC beam including creep and shrinkage effect is presented. In such plated beams, tensile forces develop in the bonded plate, and these have to be transferred to the original beam via interfacial shear and normal stresses. Consequently, debonding failure may occur at the plate ends due to a combination of high shear and normal interfacial stresses. These stresses between a beam and a soffit plate, within the linear elastic range, have been addressed by numerous analytical investigations. Surprisingly, none of these investigations has examined interfacial stresses while taking the creep and shrinkage effect into account. This paper presents an analytical model for the interfacial stresses between RC beam and a thin FRP plate bonded to its soffit. The influence of creep and shrinkage effect relative to the time of the casting, and the time of the loading of the beams is taken into account. Numerical examples of a typical RC beam strengthened with an externally bonded FRP plate are discussed with emphasis on the shear and normal stresses at the edge of the plate.