Integrity of Precracked Reinforced Concrete Retrofitted withComposite Laminates

本研究的目的是为使用纤维增强塑料（FRP）复合材料层压板改造的预裂钢筋混凝土的断裂和分层的潜在机制提供科学依据，并为这些系统的有效应用和安全工程设计制定设计指南。已经观察到层压梁通过几种机制失效，包括层压板的屈服，混凝土的破碎，以及复合材料从混凝土中分层而产生的脆性断裂。现有经验表明，在低于材料极限的应力和正常使用的载荷下，分层导致的断裂可能发生。本研究的重点将放在分层及其原因上，特别是在改造混凝土梁中存在弯曲和剪切联合裂缝的情况下。本文将对纤维增强塑料层合混凝土梁进行基于断裂力学的混凝土-附着体-层合层界面破坏的实验与数值结合研究。涉及不同材料和施工技术的参数调查将确定这些组合的最佳效果。该项目将得到瑞士联邦材料测试和研究实验室（EMPA）的合作，该实验室将使用本研究中使用的一致参数进行大规模试验。本研究旨在提供玻璃钢分层的基础知识，并制定所需的设计指南，以有效、经济和安全的方式对改造领域的工程应用产生直接影响。＊＊＊

9634763 Buyukozturk The objective of this research is to provide a scientific basis for the underlying mechanisms of fracture and delamination of precracked reinforced concrete retrofitted using fiber-reinforced plastic (FRP) composite laminates, and to develop design guidelines for efficient applications and safe engineering designs of these systems. Laminated beams have been observed to fail through several mechanisms, including yielding of the laminate, crushing of the concrete, and brittle fracture through delamination of the composite from the concrete. Available experience has shown that fracture through delamination can occur at stress below material limits and under loads within normal service. The emphasis of this study will be on delamination and its causes, specifically in the presence of combined flexural and shear cracks in the retrofitted concrete beam. Fracture mechanics based combined experimental and numerical studies of failure initiating from the concrete-adherent-laminate interface region will be performed on concrete beams laminated with fiber-reinforced plastics. Parametric investigations involving different materials and construction techniques will determine the optimum effectiveness of these combinations. The project will have the collaboration of Swiss Federal Laboratories for Materials Testing and Research (EMPA) in Switzerland where large scale tests will be conducted with consistent parameters as will be used in this study. This research is expected to provide a fundamental knowledge of FRP delamination, and be developing the needed design guidelines to have a direct impact on engineering application in the retrofitting field in an efficient, economical, and safe manner. ***