A New Approach for Adhesive Stress Analysis of a Beam Bonded with Composite Plate Having Variable Fiber Spacing

Abstract

External bonding of FRP plates or sheets has emerged as a popular method for strengthening reinforced concrete structures. Debonding along the FRP-concrete interface can lead to premature failure of the structures. Shear and normal stresses (in the thickness direction) at interfaces (referred to as interfacial shear and transverse normal stresses hereafter) have played a significant role in understanding this premature debonding failure of such hybrid structures. Extensive experimental and analytical analyses have been undertaken to investigate this problem. Large discrepancies have been found from various studies. This paper reports a closed-form formulation for interfacial stresses in plated beams. The analysis is based on the deformation compatibility approach developed by Tounsi and Benyoucef [8] where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. The composite plate with variable fiber spacing bonded to reinforced concrete beam is considered in the present study. In addition, an unrealistic restriction of the same curvatures in the RC beam and FRP panel commonly used in most of the existing studies is released in the present theoretical formulation. Compared with previously published analytical results, this one improves the accuracy of predicting the transverse normal stresses and the solution remains a closed form.