新型高延性复材混凝土梁的力学性能及设计理论

Using fibre reinforced polymer (FRP) bars to substitute steel bars as reinforcements could significantly increase the durability and service life span of the reinforced concrete structures. However, concerns on the lack of ductility impede the wide application of FRP RC beams. In order to address such a concern, a novel form of FRP reinforced concrete (RC) beams is proposed in this research project. Such a novel FRP RC beam typically consists of the following components: (1) out FRP tube; (2) inner FRP tube positioned in the compression zone of the beam; (3) concrete filled in the inner FRP tube, namely “confined concrete core” or “concrete core”; (4) concrete filled between out and inner FRP tubes, namely “concrete body”; (5) tension FRP bars. The novel FRP RC beam is expected to fail in a ductile manner by the crushing of the concrete core under the strong confinement exerted by the inner FRP tube. Understanding of the mechanical behavior and design method of such a novel beam will be gained via a series of tests and in-depth finite element analysis. It is believed that the proposed research project would initiate and advance the application of such a novel beam, and provide with a promising choice for constructing noncorrosive infrastructure.

纤维增强复合材料筋（简称“复材筋”或“纤维筋”）替代钢筋作为混凝土结构的筋材，能够避免由于钢筋锈蚀引发的耐久性不足问题，从而大大提高混凝土结构的服役寿命。然而，复材筋混凝土梁延性不足，限制了它的进一步应用。本项目针对复材筋混凝土梁延性不足问题，提出了一种新型高延性复材混凝土梁，它由（1）复材外管；（2）配置于梁受压区的复材内管；（3）填充于复材内管的“核心混凝土”；（4）填充于复材外管与复材内管间的“主体混凝土”以及（5）纵向受拉复材筋组成。新型复材混凝土梁利用在复材内管强约束下作用下“核心混凝土”压碎破坏呈显著延性的特点，实现破坏的高延性，同时保留普通复材筋混凝土梁的耐腐蚀性特征。将通过试验研究、有限元分析和理论分析，获得此新型高延性复材混凝土梁的破坏机理及力学性能特征，建立系统的设计方法。本项目的研究成果将为其工程应用提供科技支撑。

纤维增强复合材料筋（简称“复材筋”或“纤维筋”）替代钢筋作为混凝土结构的筋材，能够避免由于钢筋锈蚀引发的耐久性不足问题，从而大大提升混凝土结构的服役寿命。然而，复材筋增强混凝土梁延性不足，限制了它的进一步应用。本项目针对复材增强混凝土梁延性不足问题，提出了新型高延性复材增强混凝土梁。它由（1）复材外管；（2）配置于梁受压区的复材内管；（3）填充于复材内管的“核心混凝土”；（4）填充于复材外管与复材内管间的“主体混凝土”以及（5）纵向受拉复材筋组成。新型复材混凝土梁利用在复材内管强约束下作用下“核心混凝土”压碎破坏呈显著延性的特点，实现破坏的高延性，同时保留普通复材筋混凝土梁的耐腐蚀性特征。本项目并围绕新型复材混凝土梁的破裂机理和设计理论中关键科学问题展开了系统的研究。通过系统的试验研究和理论分析，深入地研究了新型梁的破裂机理，并揭示各参数对其破裂机理的影响规律。研究了小口径复材管约束混凝土的受压性能，验证常用应力-应变模型的适用性。基于核心混凝土的应力应变模型和平截面假定，建立了新型复材增强混凝土梁的开裂荷载和极限承载能力的预测方法。该项目的研究为该新型梁的工程应用提供很好的理论指导。