Analytical and Numerical Models of Steel I-Section Beam-Columns Strengthened with Bonded Prestressed FRP Laminates

Fibre Reinforced Polymer (FRP) laminate are currently used in strengthening steel structures having a significant favorable effect on the member capacity. Researches have been focused on FRP strength-ened beams or columns; thus, I-section beam-columns strengthened with prestressed bonded FRP laminate are scrutinized. Steel yielding, laminate rupture and/or laminate interfacial debonding common failure modes af-fecting the strengthened beam-columns capacity: debonding commonly leads to a premature failure. Prestress-ing the FRP laminate may delay this premature failure. Equations are analytically developed to evaluate the interfacial shear and normal stresses between the laminate and the steel; hence, the maximum stresses at debond-ing are evaluated. Thus, the capacity of a beam-column with prestressed FRP laminate is analytically estimated. A nonlinear numerical model is then developed for these beam-columns. The model is verified against exper-imental results available from literature. Then, a parametric study is conducted using the numerical model. Based on these results, a regression analysis is performed and the capacity of beam-columns with prestressed FRP laminate is numerically estimated considering steel yielding or FRP laminate rupture. Results of the nu-merical and analytical models lead to a proposal for evaluating the FRP strengthened beam-column capacity and the need for prestressing the FRP laminate.