Analysis of interfacial shear stresses in beams strengthened with bonded prestressed laminates

In this paper, the problem of interfacial shear stresses in beams strengthened with bonded prestressed composite laminates is analyzed using linear elastic theory. The analysis provided a closed-form formula for calculating the critical maximum shear stress at the end of the laminate for a beam with arbitrary cross-section and material. A demonstration study on strengthening an existing steel bridge using this technique has also been conducted using FE-analysis. The results from both analyses agreed very well. Also, a parametric study is performed in order to identify the effects of various geometrical and material properties on the magnitude of interfacial shear stresses. The results show that there exists high concentration of shear stresses at the ends of the laminate, which might result in a premature failure of the strengthening scheme at these locations. Material properties such as laminate and adhesive stiffness and the dimensions of the laminate where all found to have a marked effect on the magnitude of maximum shear stress in the composite member.