Innovative lateral load resisting systems for mid-rise timber frame buildings

自2009年以来，加拿大各省和联邦司法管辖区修改了各自的建筑法规，将住宅木结构建筑的层数限制从4层增加到6层。高度的增加增加了对更坚固的剪力墙体系的需求，用于建造中层(最高6层)的木结构建筑，这些建筑通常比低层(最高4层)建筑需要更高的抗重力和横向荷载。与强木框架剪力墙相关的研究很有限。简单地增强传统剪力墙的抗力可能会影响结构的延性和耗能能力等其他结构性能，而延性和耗能能力是影响结构在地震荷载作用下性能的两个关键特征。在这项研究计划中，主要目的是开发一种更强大的剪力墙体系，可以用于建造延性和耗能能力与传统墙体相当的中层木结构建筑。 在拟议的研究中，新开发的墙体体系将通过重新布置传统剪力墙中使用的三个主要构件：尺寸木材、护板和钉子来实现高水平抗力。多排钉子将沿着护套板的边缘对齐，因为这些钉子节点有望控制墙体体系的破坏模式和侧向抗力。同时，木质框架将采用多个板材和螺柱进行加固，以避免框架构件的破坏。这些增强的板材和螺柱也可以以90度旋转放置，将尺寸较大的木材的宽面钉到护套板上，这类似于中间层剪力墙系统。在这种情况下，使用了多剪多排套层框架钉。需要一个强大的压紧系统来防止升降故障。 在本研究项目中，将通过试验研究和数值模拟分析来研究新开发的剪力墙体系的结构性能。两名1-2年级的硕士研究生将研究在强剪力墙中使用的连接性能。在第一阶段结束时，将获得不同配置的连接的失效模式和力学性能。两名博士生将在第二阶段继续进行体系层面的研究。其中一名博士生将专注于剪力墙设计细节的优化。另一名博士生将专注于木材和木材混合建筑在地震荷载下的结构性能。在本次研究的最后，希望能从节点、墙体体系和整个建筑三个层面对新开发的剪力墙体系的结构性能有一个更好的了解。

Since 2009, various provincial and federal jurisdictions in Canada have amended their respective building codes to increase the storey limit of residential wood frame buildings from 4 to 6 storeys. Increases in height have raised the demand for a stronger shear wall system for construction of mid-rise (up to 6 storey) timber frame buildings that usually require higher resistance against gravity and lateral loads than low-rise (up to 4 storey) buildings. Research related to strong wood frame shear walls is limited. Simply reinforcing the resistance of the traditional shear wall may compromise other structural properties, such as ductility and energy dissipation capacity, which are two of the key characteristics affecting the performance of structures under earthquake loads. In this research program, the main aim is to develop a stronger shear wall system that can be used in construction of mid-rise timber frame buildings that has comparable ductility and energy dissipation capacity to traditional walls. In the proposed research, the high lateral resistance of the newly developed wall system will be achieved by re-arranging the three main components used in traditional shear walls: dimension lumber, sheathing panels and nails. Multi-rows of nails will be aligned along the edges of sheathing panels as these nail joints are expected to control the failure mode and lateral resistance of the wall system. Meanwhile, the timber frame will be enhanced by using multiple plates and studs to avoid failure at the frame members. These enhanced plates and studs can also be placed at a 90 rotation with the wider face of dimension lumber nailed to the sheathing panels, which is similar to a midply shear wall system. In this case, multi-shear and multi-row sheathing-to-framing nails are used. A strong hold-down system is required to prevent up-lift failure. In this research program, the structural performance of the newly developed shear wall system will be investigated through both experimental study and numerical modeling analysis. Two master students in years 1-2 will investigate the performance of connections used in the strong shear walls. At the end of phase 1, the failure mode and mechanical properties of connections with various configurations will be obtained. Two PhD students will continue the research at the system level in phase 2. One of the PhD students will focus on the optimization of design details of shear walls. The other PhD student will focus on the structural performance of timber and timber-based hybrid buildings under seismic load. At the end of this research, it is expected that a better understanding of the structural performance of the newly developed shear wall system will be achieved on three levels: joints, wall systems and the whole building.