Integrity of Precracked Reinforced Concrete Retrofitted withComposite Laminates

9634763 Buyukozturk这项研究的目的是为使用纤维增强塑料(FRP)复合材料层板加固的预裂钢筋混凝土的断裂和分层的潜在机理提供科学依据，并为这些系统的有效应用和安全的工程设计制定设计指南。已经观察到层合梁的失效机制有几种，包括层合板的屈服、混凝土的破碎以及复合材料从混凝土中剥离而导致的脆性断裂。现有的经验表明，在材料极限以下的应力和正常使用的载荷下，可能会发生分层断裂。这项研究的重点将是分层及其原因，特别是在加固混凝土梁中存在弯曲和剪切组合裂缝的情况下。以断裂力学为基础，对纤维增强塑料叠层混凝土梁进行了混凝土-粘结-层合界面区破坏的综合试验和数值研究。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。该项目将与瑞士联邦材料测试和研究实验室(EMPA)合作，在那里将使用本研究中将使用的一致参数进行大规模测试。这项研究有望提供FRP分层的基本知识，并开发所需的设计指南，以高效、经济和安全的方式直接影响加固领域的工程应用。***

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. ***