纳米高强片材加固混凝土梁的界面力学特性研究

Rehabilitation of concrete structures has become an important field in civil engineering. External bonding of high strength and lightweight materials such as FRP (EB-FRP) is expected to replace traditional concrete repair and steel plating technologies due to its advantages in construction convenience. However, it is noted recently that engineers return to conventional steel plating, for the concerns about the brittleness of FRP materials as well as the difficulties involved in bonding. The principal investigator (PI) collaborates with material scientists recently, and successfully developed a strengthening technology using a new type of material - nano treated steel sheet (nano sheet). The nano sheet has the advantages of FRP in high strength and lightweight while retaining the ductile nature of steel; therefore, it is an ideal material for structural rehabilitation. As the nano sheet is very thin, normal fastening technology using bolt is not applicable, because bolts can easily cut into the thin sheet. In this case, the hybrid-bonded (HB) technology, which was developed by the PI for bonding of thin materials, will be ideal for increasing interfacial bond strength and avoid debonding of the reinforcing material. The main objective of this proposed project is to develop a HB technology that is suitable for the nano sheet and its corresponding design theory. This project will first develop a bond-slip relationship from tests, then mathematically derive the models for the effective bond length and bond strength using the bond-slip relationship, and finally develop design theory and methodology for strengthening RC beams using the nano sheet. The successful completion of the project will build a solid foundation for application of the new material to rehabilitation of RC structures.

混凝土结构的维修加固现已成为土木工程的一个重要领域。外贴轻质高强材料如FRP 加固法以其施工便捷等优点，有希望取代传统的混凝土修补和钢板粘贴技术。然而工程界经过近年来的实践，开始显露出回头使用钢板加固的趋势。其中重要原因之一是FRP材料的脆性且难以锚固。申请人最近和材料科学家合作，用新材料纳米钢片加固结构，收到了很好的效果。该材料既有FRP的强度和轻质，又具有钢材的延性和韧性，是理想的加固材料。由于纳米钢片很薄，传统的铆钉锚固法会割裂片材。而申请人前些年开发的混合粘贴技术则很适合该材料的锚固。因此本课题的目的是研发适用于纳米钢片的混合粘贴技术及其理论。本课题拟通过实验建立粘结界面的粘结滑移关系模型，然后用所得的粘结滑移关系数学推导有效粘结长度和粘结强度模型，最后用建立的理论模型研究纳米钢片加固梁的结构特性及设计理论。本课题的顺利完成将为用纳米钢片加固混凝土结构奠定良好的基础。

混凝土结构的维修加固现已成为土木工程的一个重要领域。外贴轻质高强材料如FRP加固法以其施工便捷等优点，有希望取代传统的混凝土修补和钢板粘贴技术。然而工程界经过近年来的实践，开始显露出回头使用钢板加固的趋势。其中重要原因之一是FRP 材料的脆性且难以锚固。申请人最近和材料科学家合作，用新材料纳米钢片加固结构，收到了很好的效果。该材料既有FRP 的强度和轻质，又具有钢材的延性和韧性，是理想的加固材料。由于纳米钢片很薄，传统的铆钉锚固法会割裂片材。而申请人前些年开发的混合粘贴技术则很适合该材料的锚固。因此本课题的目的是研发适用于纳米钢片的混合粘贴技术及其理论。本课题通过实验建立了粘结界面的粘结滑移关系模型，然后用所得的粘结滑移关系推导有效粘结长度和粘结强度模型，最后用建立的理论模型研究纳米钢片加固梁的结构特性及设计理论。本课题为用纳米钢片加固混凝土结构奠定了良好的基础。