Corrosion Resistant Rehabilitation of Offshore Structures by Using FRP

点击翻译按钮获取中文摘要

Strength of structure repaired with externally bonded FRP sheet depends on bonding strength between FRP sheets and substrate. It is important to evaluate a bonding strength between FRP sheets and substrate. Numerous researchers have noticed debond and peel during tests and have voiced concern related to this mode of failure. Further investigations into mechanisms of peel and the characteristics of the composites-substrate interface during debonding and peeling are thus critical to understanding both design requirements and long-term use potential of composite plates as a means of rehabilitation of infrastructure elements. In this study, we investigated about two topics : First is durability of a single notch beam repaired with externally bonded composite under fatigue loading, second is environmental durability of steel attached with externally bonded composite in marine environment.A single edge notched beam repaired with externally bonded CFRP sheet was analyzed under three-point-ben … More ding load based on linear elastic fracture mechanics. Reduction of stress intensity factor at the crack tip was calculated theoretically. The increase in fatigue strength of test specimens reinforced with various CFRP sheet patches was confirmed experimentally. Resistance effects of crack propagation under fatigue loading were also evaluated experimentally. Crack growth of a repaired specimen was controlled by the effective stress intensity factor proposed in the present paper.The environmental durability of steel members reinforced by external FRP sheets was successfully evaluated in marine environment based on the proposed "Membrane Peeling" test method. Four kinds of CFRP sheets were prepared : four resins, epoxy, vinyl ester, isophthalic and orthophthalic polyester resin. The bonding strength of steel member reinforced by epoxy resin was found to be as twice as strong that of steel member reinforced by the others resin before these test specimens were immersed in seawater. On the other hand, steel member reinforced by epoxy resin got most decreased debonding strength after immersion in seawater for one month. Bonding strength degraded immediately after immersion for six months, because CF-Vinyl ester and CF-Isophthalic resin were showed interface peeling between CF sheet and substrate. After immersion for twelve months, bonding strength deteriorated due to change of fracture mode. Less