Corrosion Resistant Rehabilitation of Offshore Structures by Using FRP

外贴FRP片材加固结构的强度取决于FRP片材与基材的粘结强度。评价玻璃钢片材与基材之间的粘结强度是非常重要的。许多研究人员在测试过程中注意到了脱粘和剥离，并对这种失败模式表示了担忧。因此，进一步研究剥离机理以及剥离和剥离过程中复合材料-基材界面的特征，对于理解复合板作为修复基础设施元件的手段的设计要求和长期使用潜力是至关重要的。本文主要研究了两个方面的问题：一是外贴复合材料修补缺口梁在疲劳荷载作用下的耐久性；二是海洋环境下外贴复合材料加固单边缺口梁的环境耐久性。本文对一根单边缺口梁进行了三点Ben-…分析基于线弹性断裂力学的更多丁丁载荷。从理论上计算了裂纹尖端应力强度因子的折减。试验证实，不同碳纤维布补片加固试件的疲劳强度均有所提高。此外，还对疲劳载荷下裂纹扩展的阻力效应进行了实验评价。采用本文提出的有效应力强度因子控制修复试件的裂纹扩展，并基于所提出的“剥膜”试验方法，成功地评估了海洋环境中外贴FRP片材加固钢构件的环境耐久性。制备了四种碳纤维增强塑料板材：四种树脂、环氧树脂、乙烯基酯树脂、间苯二甲酸酯树脂和邻苯二甲酸乙二醇酯树脂。在海水中浸泡前，用环氧树脂加固的钢构件的粘结强度是用其他树脂加固的钢构件的两倍。另一方面，环氧树脂增强钢构件在海水中浸泡一个月后，剥离强度下降幅度最大。在浸泡6个月后，由于CF-乙烯基酯和CF-间苯二甲酸树脂在CF板和基材之间出现界面剥离，粘接强度立即下降。浸泡12个月后，由于断裂模式的改变，粘结强度变差。较少

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