STRUCTURAL INTEGRITY OF BEAMS STRENGTHENED WITH FRP PLATES - ANALYSIS OF THE ADHESIVE LAYER

The CIRIA organisation is currently leading a project, RP 645, entitled "Strengthening metallic structures using externally bonded fibre reinforced polymers" prepared by Faber Maunsell and University of Surrey. The final report is due to be published in May 2003. This guideline covers all aspects of the material, design and installation regarding the application of FRP strengthening systems to beam structures such as in metal bridges. Within the design section of this report, an alternative approach to design and analysis of the adhesive layer is proposed. Rather than current design practice which considers average stresses within the adhesive layer, profiles of the peel and shear stresses along the adhesive layer are calculated. The designer then compares the maximum values of these stresses to inferred peak stress values from lap shear test data. This paper summarises the derivation of the stress analysis for the adhesive layer. Both uniform and tapered reinforcements are considered. Included in the analysis are the effects of both pre-tensioning the FRP plate and thermally induced stresses. The paper also addresses the practical design issues of what are the acceptable level of stresses within the adhesive layer and the corresponding issue of how to interpret results from lap shear test data. For the covering abstract see ITRD E122906.