Proposed design guidelines for strengthening of steel bridges with FRP materials

This pctpcr focuses on the use of externally bonded high modulus carbon fiber reinforced polymer (HM CFRP) materials to strengthen steel bridges and st ructures. Proper installation of the CFRP materials is necessary to prevent premature failure due to debondi ng. The paper proposes guidelines and installation techniques based on the best practice reported in the literature and the extensive practical experience in bonding of composite ma terials. The surface preparat ion of the materials, the application of the adhesive and the deta iling of the strengthening .ue provided in deta il. The design guidel ines include the structura l design criteri a for the use of high modulus CFRP materia ls as flexural strengthening system of typical steelconcrete composite bridge girders. The flexural design procedure is based on a moment-cur\'aturc analysis and a specified increase of the live load carried by the bridge to satisfy specific serviceabil ity requirements. A bond model is also described which can be used to calculate the shear and peel stresses wi thin the adhesive thickness. To prevent a premature debonding fai lure of the st rengthening system, the criteria specify a maximum principle stress in the adhesive which cannot be exceeded for a given characterist ic strength of an adhesive. A worked example is presented to illustrate the proposed flexural des ign approach. The research findings conclude that high modulus CFR P materia ls provide a promising a lternative for strengthening steel bridges tha i can be eas ily designed and insta lled to increase their strength and stiffness. © 2006 Elsevier Ltd. All rights rese rved. K".\'u·o/,ds: High modulus carbon fiber reinforced polymers; Steel structu res; Design guidelines