竹-木夹板剪力墙抗侧力机理及设计方法研究

Midply shear wall is featured by its high lateral performance, and can be seen as an important based technology in the area of mid-rise timber structures. However, when subjected to lateral loads, midply shear walls fabricated with wood-based structural panels normally exhibit stiffness and strength degradation due to the failure of nail connections in terms of panel tearing and nail withdrawal, while most of the sheathing panels and studs are still undamaged. In order to avoid such failure mode, ply-bamboo panel, which possesses high strength and homogeneity, is employed to replace normal wood-based sheathing as the middle panel in this project. Moreover, fastener with high withdrawal and bending behavior will be used to connect the middle ply-bamboo panel and the bilateral studs. This project will provide a comprehensive investigation into the lateral performance of bamboo-wood midply shear walls, involving: 1) Lateral tests and mechanism analysis will be conducted on the double-shear connections to reveal the mechanical behavior and the interaction among the fastener, the middle ply-bamboo panel and the bilateral studs. 2) Pseudo static tests and parametric numerical modeling on full-scale wall specimens will be carried out to clarify the lateral load resisting mechanism of the bamboo-wood midply shear walls. 3) Based on the parametric numerical modeling, seismic reliability and failure probability of the walls will be evaluated with the consideration into various uncertainties. 4) Scientifically reasonable design methods will be proposed for the bamboo-wood midply shear walls. The implement of this project should be able to obtain a type of excellent lateral load resisting member which may contribute to the development of mid-rise timber structures, and is thus of both scientific and engineering value.

夹板剪力墙的抗侧力性能优异，是木结构建筑向中高层迈进的一项重要技术基础。然而，采用木基结构板材制成的夹板剪力墙在侧向力作用下易出现钉子划破墙板和钉子拔出等破坏，使墙体承载性能严重退化，而墙体中大部分木材的强度远未充分发挥。为此，本项目提出以强度高、材质均匀的竹胶板作为中心夹板，并配以抗拔、抗弯性能好的钉连接件，以期改善上述破坏模式，提升墙体抗侧力性能，主要研究内容包括：1）通过竹胶板双剪钉连接的试验与理论分析，揭示其受力机理与破坏形态；2）通过竹-木夹板剪力墙的抗侧力试验和参数化数值模拟分析，阐明抗侧力机理；3）基于数值模拟揭示竹-木夹板剪力墙在地震作用下的结构响应变化规律，并结合可靠度分析阐明各不确定性因素对失效概率的影响；4）探究竹-木夹板剪力墙的抗侧力设计方法。本项目的实施有助于形成高效、高性能的竹-木抗侧力构件，推动我国中高层木结构的发展，具有重要的科学意义和工程应用价值。

本项目围绕竹胶板夹板剪力墙的抗侧力机理及其内部双剪螺钉连接的力学性能进行了系统性研究，主要研究内容和结论如下：首先，通过600个竹胶板试件的销槽承压试验，评估了竹胶板的销槽承压性能，提出了销槽承压强度理论计算公式。其次，针对竹胶板双剪螺钉连接的力学性能，进行了160个单调和低周反复加载试验，揭示了自攻螺钉与木墙骨、竹胶板间的相互作用机理，并得到了合理的恢复力模型，其结果表明：竹胶板双剪螺钉连接能充分利用自攻螺钉的高抗拔性能和竹胶板的优异承压性能，表现出比常规双剪钉连接高得多的承载能力和刚度。另外，理论分析结果表明，基于欧洲规范EC5和我国木结构设计规范GB50005-2017的算得的竹胶板双剪螺钉连接承载能力偏于保守，其原因在于对螺钉的绳索效应和竹胶板销槽承压强度的低估。再次，进行了8片竹胶板覆面剪力墙和15片竹胶板夹板剪力墙的单调和低周反复加载试验研究，分析了竹胶板厚度、钉间距、墙肢长度等参数变化对抗侧力性能的影响，明确了其在往复加载过程中的损伤累积规律，探究了竹胶板和自攻螺钉的使用对夹板剪力墙抗侧力性能的增强效果。结果表明，竹胶板的高强度和自攻螺钉的高抗拔优势得到充分发挥，有效避免了墙体中的板边撕裂和钉子拔出破坏，其抗剪刚度比常规夹板剪力墙高11.2%-63%，抗剪强度提高了51.2%-107.1%。最后，基于有限元软件OpenSees进行了竹胶板夹板剪力墙的参数化数值模拟分析，结果表明：竹胶板夹板剪力墙的抗侧力性能与墙肢长度成正比关系，与边缘钉间距负相关，这均符合轻型木结构墙体的一般规律。