基于多尺度损伤理论的RC板柱节点抗冲切分析方法研究

Owing to the benefits such as less space occupied, simple and economical, reinforced concrete slab-column structures have been widely applied to various types of buildings. However, the punching failure in slab-column joints has become one of the most severe problems of slab-column structures. Therefore, the analysis method on punching resistance and failure process of reinforced concrete slab-column joint serves as an essential support in predicting the mechanical behaviors, failure modes and overall safety. In this project, the distribution of aggregates, mortar and micro-voids of concrete are obtained by CT scan, while the mesoscopic crack propagation can be simulated by the experimental results firstly. Secondly, the multiscale energy bridging is applied to formulate the one mapping between mesoscopic crack propagation and macroscopic damage evolution, and the multiscale damage model could be established. Thirdly, with the proposed multiscale damage model, the numerical simulation of slab-column joint will be carried out, which provides a unified simulation for both the cracking/failure process and overall load- deflection curve of structure. Finally, the simulation results are testified and verified by the punching test of slab-column joint. This project offers an innovative method for the nonlinear analysis and safety assessment of reinforced concrete slab-column joints.

钢筋混凝土板柱结构具有水平构件占用空间小、施工简便、经济性好等优势，广泛运用于各类建筑中。然而，由于板柱节点冲切破坏导致的结构破坏层出不穷。因此，对板柱节点抗冲切性能与破坏全过程分析方法的研究，能够为评估节点力学性能、预测裂纹出现位置、保障结构安全提供理论支持。本项目在多尺度损伤理论框架下开展研究。1、在细观尺度，通过CT扫描试验，揭示混凝土骨料、水泥砂浆和细观微孔洞的分布，据此模拟混凝土细观裂纹的开展。通过多尺度能量积分，给出细观裂纹宽度与宏观损伤变量之间的关系，建立完善的混凝土多尺度损伤本构模型。2、在宏观尺度，将多尺度损伤本构模型用于板柱节点抗冲切非线性分析，建立能够同时获得板柱节点抗冲切承载力、变形等力学特征与裂纹开展直至破坏全过程的分析模型。最后，将数值模拟的结果与板柱节点抗冲切试验结果进行对比，验证模型的正确性。为板柱节点抗冲切分析提供新的方法并为其安全性能评估提供技术依据。

对板柱节点抗冲切性能与破坏全过程分析方法的研究，能够为评估节点力学性能、预测裂纹出现位置、保障结构安全提供理论支持。本项目围绕研究目标展开，研究计划按预期执行，并取得了预期成果。项目开展了以下4项研究：1、在细观尺度，通过CT扫描试验，揭示混凝土骨料、水泥砂浆和细观微孔洞的分布，据此模拟混凝土细观裂纹的开展；2、通过多尺度能量积分，给出细观裂纹宽度与宏观损伤变量之间的关系，建立完善的混凝土多尺度损伤本构模型；3、进行了4块板柱节点抗冲切试验，获得其变形、承载力、破坏模式等，揭示其受力性能；4、将多尺度损伤本构模型用于板柱节点抗冲切非线性分析，建立了能够同时获得板柱节点抗冲切承载力、变形等力学特征与裂纹开展直至破坏全过程的分析模型。围绕混凝土板柱节点及其在结构工程中的推广，项目发表论文6篇，授权专利4项，具有一定工程推广的潜力。