Design guidance for balloon-framed CLT structures

木结构建筑正在兴起！公众对建筑和维护结构对环境影响的认识的提高极大地增加了对可持续建筑方法的需求，并引发了木材使用的复兴，特别是交错层压木材(CLT)。高层住宅和非住宅CLT建筑在北美变得越来越普遍，最高可达12层的封装式大型木结构的设计规定已纳入加拿大国家建筑法规。大多数先前的研究和加拿大木材工程设计标准中产生的设计指南仅限于平台式结构，即一层的天花板形成下一层的墙的平台。相比之下，气球框架结构提供了几个优势，包括消除了楼层之间垂直于木纹的承重和建筑物高度的累积收缩，以及需要较少的嵌板来产生细长的嵌板长宽比，以及减少建筑物高度上的连接。我的研究计划的长期目标是为气球类型的CLT建筑开发并提供可靠的工程设计指南，特别是通过解决它们的抗震性能和防止不成比例的倒塌。在拟议的NSERC DG研究计划范围内，我的团队将与设计和建筑行业密切合作，推进三个直接相关的研究领域：1)开发新型气泡式CLT剪力墙连接系统，例如结合超弹性支座和钢棒连接各个墙段；2)制定气泡式CLT抗侧向荷载体系的设计规定，该体系由带周边CLT剪力墙的混凝土核心和带支撑木材(或钢)周边框架的CLT核心组成；以及3)提供证据证明气胀式CLT体系能够在支撑构件突然丢失的情况下开发替代荷载路径，以防止不成比例的倒塌。我的团队将通过概念、实验、数值和分析调查来推进这些研究领域。从整体上解决与气球型CLT建筑相关的研究问题，将使我的研究计划有别于其他努力，后者往往专注于这些问题的个别子集。拟议的计划将利用和推动当前专注于可持续性和创新木结构的倡议的势头，利用我所在团队的成功研究倡议，并塑造省、国和全球高层木结构的未来研究议程。最终，通过在这一领域发挥领导作用，该计划的成功实施将对木材的结构使用产生决定性影响，并将增加其在高层住宅和非住宅建筑中的市场份额。

Wood structures are on the rise! Heightened public awareness regarding the environmental impact of building and maintaining structures has dramatically increased the demand for sustainable construction methods and has initiated a resurgence in the use of wood, in particular Cross-Laminated Timber (CLT). Tall residential and non-residential CLT construction is becoming common in North America, and design provisions for encapsulated mass timber structures up to 12 stories tall have been incorporated into the National Building Code of Canada. Most previous research and the resulting design guidance in the Canadian Standard for Engineering Design in Wood is limited to platform-type construction, where one storey's ceiling forms the platform for the next storey's walls. In contrast, balloon-framed structures, where the walls are continuous over multiple storeys, offer several advantages including eliminating perpendicular-to-the-wood-grain bearing between floors and cumulative shrinkage over the building height, and requiring fewer panels to create slender panel aspect ratios and fewer connections over the height of a building. The long-term goal of my research program is to develop, and make available, reliable engineering design guidance for balloon-type CLT buildings, specifically by addressing their seismic performance and the prevention of disproportionate collapse. Within the proposed NSERC DG research program, my team, in close collaboration with the design and construction industry, will advance three immediately relevant research areas: 1) Development of novel low-damage connection systems for balloon-type CLT shear walls, such as hyperelastic bearings combined with steel rods to connect individual wall segments; 2) Development of design provisions for balloon-type CLT lateral load resisting systems consisting of concrete cores with perimeter CLT shear walls and CLT cores with braced timber (or steel) perimeter frames; and 3) Providing the proof that balloon-type CLT systems are able to develop alternative load paths in the case of sudden supporting element loss, to prevent disproportionate collapse. My team will advance these research areas through conceptual, experimental, numerical, and analytical investigations. Addressing research questions related to balloon-type CLT buildings holistically will differentiate my research program from other efforts, which tend to focus on individual subsets of these problems. The proposed program will exploit and fuel the current momentum of initiatives focused on sustainability and innovative wood construction, leverage successful research initiatives in my group, and shape future research agendas in tall wood construction provincially, nationally and globally. Ultimately, by taking leadership in this area, successful implementation of the program will have a decisive impact on the structural use of wood and will increase its market share in tall residential and non-residential buildings.