自攻螺钉-连接板拼接木梁力学机理及设计方法研究

Splicing technique of timber components is an important foundation for the development of large-space and long-span timber structures. However, current splicing techniques still have some shortcomings, such as small flexural stiffness, low bearing capacity etc. These shortcomings have limited the development of long-span timber structures. Hence, a new splicing technique with large flexural stiffness and high bearing capacity will be developed in this project. The excellent withdrawal property of the self-tapping screw (STS) and the connection plate with high strength (such as steel plate, bamboo plywood plate and reconsolidated bamboo plate) will be used to connect the spliced beams. Withdrawal performance tests will be performed to study the anchor performance of the STSs under tension and flexural-shear loading. The mechanical and deformation mechanism of the STSs-plate composite connectors will be thoroughly investigated. The flexural behavior of the splice beams with new splice joint will be studied under bending performance test. The mechanical mechanism will be revealed by theoretical analysis. Furthermore, effects of various design parameters on the flexural performance of the splice beams will be investigated using numerical approach. The practical calculation models of the flexural bearing capacity and moment-rotation relationships for splice joint will be proposed combining the theoretical derivation and experimental study. Finally, a rational design guideline will be developed to make suggestions for engineering design，structural measures and construction. This project will provide an important technical support for the development of large-space and long-span timber structures.

木构件的拼接技术是木结构建筑向大空间、大跨度方向迈进的一个重要基础。然而，现有木构件拼接技术中仍存在拼接节点抗弯刚度小、承载能力低等问题，已成为大跨木结构发展“短板”之一。为此，本项目拟运用自攻螺钉的优异锚固性能和连接板（钢板、竹胶合板和重组竹板）的高强度，提出一种抗弯刚度大、承载力高的木梁拼接技术。主要研究内容包括：通过拉拔锚固性能试验，研究自攻螺钉在拉力作用和弯剪组合作用下的锚固性能，揭示自攻螺钉-连接板组合连接件的力学机理和变形机制；通过拼接梁抗弯性能试验和理论分析，研究带新型拼接节点拼接梁的受弯性能，揭示其力学机理；继而，基于数值模拟，研究不同设计参数对拼接梁受弯性能的影响，基于理论推导和试验研究，提出该类节点承载力计算模型和拼接截面弯矩-转角关系模型；最后提出并形成科学合理的工程设计、构造措施与施工建议等成套技术。本项目为促进大空间、大跨度木结构建筑发展提供重要技术支撑。

大空间、大跨度木结构建筑的主要受力构件往往需要通过拼接节点形成，合理的木构件拼接技术是保证大跨木结构安全的核心问题。项目提出了自攻螺钉-连接板拼接技术，开展了拼接木梁在弯矩作用下的失效模式和受力机理研究，围绕自攻螺钉锚固力学性能、自攻螺钉-连接板（钢板、竹胶板、重组竹板）抗剪连接节点失效机理、拼接木梁受弯节点连接技术和设计方法等方面展开了系统研究，取得了创新性成果：（1）运用精细化数值模拟及试验研究，揭示了自攻螺钉-连接板节点的剪切失效机理；（2）揭示了自攻螺钉-连接板拼接木梁节点失效机理，系统分析了主要设计参数对于拼接节点连接破坏模式、刚度、极限承载力的影响；（3）提出了适用于大跨木结构木梁的自攻螺钉-连接板拼接节点连接形式，建立了新型节点连接设计方法。经过三年的研究，项目实现了既定目标，在《Engineering Structures》、 《Construction and Building Materials》、《Journal of Renewable Materials》等国际权威期刊，以及《林业工程学报》等国内林业工程领域权威期刊发表高质量论文11篇，其中SCI收录5篇，SCD收录3篇，申请并受理国家发明专利1项，授权国家实用新型专利1项，人才培养成效显著。该项目聚焦于自攻螺钉-连接板拼接梁节点连接性能研究，与爱丁堡等世界知名高校展开合作，并在多场国际学术会议做报告，在国内外产生了较大的影响。