自复位预应力胶合木框架梁柱节点的受力机理与设计方法研究

Glulam post-and-beam structural system represents a common way of building modern timber structures, and this type of structures also meets the medium and long-term development proposal in China. However, when subjected to earthquakes, glulam post-and-beam structures normally have excessive residual deformation which is caused by the concentrated damage at the beam-to-column joints. In most cases, it is either infeasible or too expensive to repair the damage after the earthquake. In order to provide seismic resilience for glulam post-and-beam structures, a kind of post-tensioned joint system with self-centering feature is proposed in this project. In such joint, post-tension tendon is employed to provide self-centering capacity to minimize the residual deformation, and energy dissipation device is employed to dissipate energy during an earthquake. This project will provide a comprehensive investigation into the mechanical behavior of the self-centering glulam beam-to-column joint. Pseudo static test on full-scale joint specimens will be conducted to clarify the influence of material nonlinearities on the joint performance, and the interaction between the self-centering mechanism and the energy dissipation mechanism within the joint will be revealed. A user-defined finite element with special consideration into the wood stiffness degradation will be developed to model the behavior of the beam-to-column contact surface. Parametric analysis will then be conducted through numerical simulations to reveal the relationship between crucial design parameters and the resistance and deformation characteristics of the joint. Theoretical formulas will be proposed for estimating the stiffness, capacity and energy dissipation of the self-centering joint, and then a design procedure for such joint will be established. This research will make significant scientific contributions to understanding the mechanical behavior of self-centering glulam beam-to-column joints. It will also contribute to the development and utilization of seismic resilient high-performance glulam timber structures in China.

胶合木框架结构绿色环保、符合建筑工业化发展方向，然而震后梁柱节点残余变形大、修复难。本项目提出自复位胶合木梁柱节点，设贯通的预应力筋提供自复位驱动、设耗能件耗散地震能量，能大幅减小震后结构损伤和残余变形，使结构功能快速恢复。本项目拟通过足尺自复位木节点拟静力试验和理论分析，阐明木材和耗能件非线性力学性态对节点力学性能的影响机制及程度，明确节点中自复位机制和耗能机制的协同作用机理，揭示节点受力机理。继而开发能考虑梁柱接触区刚度退化行为的力学分析模型，基于数值模拟和参数分析阐明节点关键设计参数与其弯剪抗力特性和形变模式的内在联系，提出节点刚度、承载力等各项力学性能指标的分析与计算方法，建立节点设计方法。本项目对揭示自复位木结构的受力机理、推动木结构向“震后可恢复功能”的抗震设计目标迈进有十分重要的科学意义，对构建新型高性能装配式木结构体系有重要工程应用价值。

胶合木框架结构绿色环保、符合建筑工业化发展方向，然而震后梁柱节点残余变形大、修复难。本项目创新性地提出自复位胶合木梁柱节点，设贯通的预应力筋提供自复位驱动、设耗能件吸收地震能量。项目主要研究内容和结果如下：（1）通过120个胶合木清材试验，揭示了胶合木端部效应对其轴向抗压刚度的影响机制和程度，得到了考虑端部效应的胶合木梁轴向抗压刚度折减系数。（2）通过对角钢耗能件和摩擦型耗能件的拟静力加载试验，获得了不同设计参数下的耗能件滞回曲线。（3）通过11个足尺自复位胶合木梁柱节点拟静力试验，阐明了木材和耗能件非线性力学性态对节点力学性能的影响机制及程度，明确了节点中自复位机制和耗能机制的协同作用机理，获得了节点滞回特性、刚度强度退化特性、破坏模式。（4）基于OpenSees开发了能考虑梁柱接触区刚度退化行为的力学分析模型，基于数值模拟和参数分析阐明了节点关键设计参数与其弯剪抗力特性和形变模式的内在联系，提出了基于拟梁法的节点刚度和承载力计算方法，进而建立了节点设计方法。（5）基于所提出的设计方法，设计了一栋自复位木框架结构，通过非线性增量动力分析研究了结构动力响应特征。本项目对揭示自复位木框架结构的受力机理、推动木结构向“震后可恢复功能”的抗震设计目标迈进做出了科学贡献，对构建可恢复功能装配式木结构具有工程应用价值。