Shear Behaviour and Strength of CFRP-Retrofitted Plate Girders

The main objective of this work is to study shear behaviour and strength of retrofitted steel structures especially: Steel Plate Girders (SPGs) and Composite Plate Girders (CPGs) retrofitted by CFRP composites bonded adhesively to web plates and loaded primarily in shear. After reviewing the existing literature an extensive experimental programme was designed and performed in four phases to test (I) 36 direct-tension specimens (II) 7 reduced-scale SPGs (III) 6 full-scale SPGs and (IV) 6 full-scale CPGs. Then theoretical investigations were performed to analysis both steel and composite plate girders. The proposed models were verified by case studies and then invested into analytical parametric studies. Practical design issues were discussed including the optimum retrofitting scheme and new design equations were proposed. The results of the experimental programme are very promising in light of increasing the ultimate load of the reference girders as high as 232% and the ductility investigations showed that retrofitted girders are still ductile. All retrofitted specimens exhibited an increase in elastic stiffness but with different ratios.