Multiscale analysis of GFRP reinforcements for concrete under special stress and environmental conditions- modelling strength and durability

研究解决了玻璃纤维增强聚合物（GFRP）钢筋混凝土结构的性能的一个关键问题。特别是，试验和数值分析的玻璃纤维复合材料和玻璃纤维增强混凝土结构提出。这些包括短期和长期的表现和随后的失败。长期性能会影响失效，这可能是为了安全地使用GFRP作为结构材料而需要解决的最关键问题。 复合GFRP筋是一种在纤维方向上具有高强度的工程材料，其通常沿筋沿着排列。GFRP钢筋由玻璃纤维和树脂基体组成，树脂基体将纤维保持在一起并保护它们免受周围介质的影响。GFRP复合材料已成功地用于混凝土结构中的钢筋，其中腐蚀或电磁惰性是一个问题。 本提案涉及GFRP钢筋设计方法、材料规范和试验方法的评估和开发，重点关注弯曲钢筋（在非典型制造条件下制造的钢筋）的机械性能、粘结性能和这些钢筋的耐久性。 与当前GFRP标准所基于的简化单一载荷水平测试相比，还解决了诸如销钉强度等异常载荷条件。提出了一种基于性能的短期和长期阻力描述，以描述极限状态和现实的安全裕度。因此，这项工作的主要目标是提供信息和设计建议的安全水平的强度，用于建筑玻璃钢筋。

The research addresses a crucial question of performance of glass fibre reinforced polymer (GFRP) reinforcements for concrete construction. In particular, testing and numerical analysis of GFRP composites and GFRP reinforced concrete structures are proposed. These include short-term and long-term performance and subsequent failure. Long-term performance influences failure and it is likely the most critical issue that needs to be addressed in order to safely use GFRPs as structural materials. The composite GFRP bar is an engineered material with high strength in the fibre direction, which is generally aligned along the bar. GFRP reinforcing bars are composed of glass fibres and a resin matrix, which holds the fibres together and protects them from the surrounding media. GFRP composites have been successfully used as reinforcement in concrete structures where corrosion or electromagnetic inertness is a concern. This proposal addresses evaluation and development of design methods, material specifications and test methods for GFRP reinforcements concentrating on mechanical performance of bent bars (bars manufactured under non-typical manufacturing conditions), bond properties, and durability of these bars. Unusual loading conditions like dowel strength are also addressed, in contrast to the simplified single load level tests on which current GFRP standards are based. A performance-based description of short and long-term resistance is proposed to describe limit states and realistic safety margins. Hence, the primary objective of this work is to provide information and design recommendations regarding safe levels of strength for GFRP bars used in construction.