可拆装混凝土连接节点受力机理

The Design for Deconstruction (DfD) concrete structure offers an opportunity of reuse of concrete components after demolition, by reducing waste concrete production from the origin, decreasing resource consumption and environmental pollution, which is conforming to the sustainable development strategy of the construction industry. It is quite a challenging work to design the concrete structure according to the DfD principle. Besides the realization of modularization and standardization for design and construction, it is also required that the concrete connections between concrete elements are easy to disassemble and re-assemble and have favorable mechanical properties. The basic theoretical research on this topic has not been carried out in the domestic and overseas. Experimental and theoretical analysis methods are adopted in this project, in order to deeply explore the mechanism of DfD concrete connections, including the shear stress mechanism of new to old concrete interface, the force transfer mechanism, and the integral and safety performance of DfD concrete connection under earthquake actions. Based on the study of this project, the bond-slip constitutive relation between new to old concrete interface can be established, which will offer a theoretical foundation for the finite element analysis of DfD concrete connections with complex multi-interface characteristics; the optimization design and performance improvement method can also be put forward, which will realize the performance control of DfD concrete connections. Therefore, this project has higher theoretical and engineering value.

可拆装混凝土结构满足了混凝土构件在拆除后二次利用的要求，从源头上减少废混凝土的产生，降低资源消耗和环境污染，符合建筑业可持续发展战略。混凝土结构实现可拆装具有一定的挑战性，除须设计和施工实现模块化和标准化，还要求混凝土构件的连接节点既方便拆卸和再安装，又具有良好的力学性能。国内外针对于此的基础理论研究尚未展开。本项目采用试验和理论分析相结合的手段，对可拆装混凝土连接节点受力机理进行深入研究，揭示新老混凝土界面剪切机理，掌握可拆装混凝土连接节点传力机制，评价其在地震作用下的整体性能和安全性能。通过本项目的研究，可建立新老混凝土界面粘结-滑移本构关系，为具有复杂多界面特征的可拆装混凝土连接节点有限元分析奠定理论基础；并提出连接节点优化设计和性能提升方法，实现对可拆装混凝土连接节点的性能控制，达到其承载力与普通整浇连接节点一致的设计目标，因此具有较高的理论和工程价值。

将可拆装设计应用于混凝土结构，能从根源上减少建筑废混凝土的产生，达到保护环境、节约资源的目的。本项目的主要研究内容包括可拆装混凝土连接节点界面特征试验与理论研究、可拆装混凝土连接节点受力性能试验研究、以及可拆装混凝土连接节点性能提升方法理论研究。取得的重要结果如下：.1. 建立了新老混凝土界面剪切黏结滑移模型：提出了改进的新老混凝土界面在受剪切力作用下的试验方法，通过与试验结果对比的方式验证了试验装置的合理性。基于试验结果，提出了考虑混凝土的强度、界面的粗糙度、外部正应力的混凝土界面剪力-滑移模型。.2. 提出了可拆装混凝土框架结构节点设计方法：提出的可拆装混凝土构件连接方法具备良好的抵抗弯矩的能力，可以用于地震区的混凝土框架结构。可拆装试件和整浇试件的裂缝发展和破坏模式存在一定的区别，新老混凝土界面的存在导致可拆装连接的后浇混凝土区域裂缝较多。.3. 揭示了可拆装混凝土框架节点抗震性能和破坏机理：设计的可拆装混凝土框架节点基本实现了等效现浇连接，满足了结构安全性的基本要求。其实际可拆装性首次得到了施工验证，拆装过程并不复杂且产生的建筑废物量大幅度降低，二次安装后的框架梁柱节点依然具有良好的抗震性能。通过有限元模型的参数分析，进一步明确了此类新型节点在地震作用下的受力机理和破坏过程，解释了可拆装混凝土节点的裂缝发展分布与整浇节点不同的根本原因。