High performance timber connections with steel perforated plate as structural fuse

由于现代工程木制品的发展取得了进步，高层木结构建筑现在在技术上是可行的。高层木结构建筑的主要问题之一是它们在地震作用下安全运行的能力。在地震作用下，理想的性能属性是结构经历大变形的能力，作为一种消散地震能量的手段，而不会倒塌。对于木结构，只有当结构中的连接包含充当能量耗散源的金属组件时，才能实现这一能力。在这项研究计划中，将探索一种利用所谓的结构保险丝来耗能的方法。这种方法已经在钢结构中得到了应用，但在木结构中的应用还需要进一步的研究。拟议的方案扩展了申请人目前的研究，以进一步开发由穿孔钢板连接两个或更多木材构件的连接系统。连接钢板和木构件的部分将用金属紧固件进行详细设计，并设计成比穿孔钢板更坚固，以确保在地震作用下钢板发生目标耗能。穿孔图案由多个按规则距离隔开的圆形孔组成。这种模式将有助于调整穿孔板，以获得所需的力学性能，如强度、刚度、极限位移和能量耗散能力，从而制定设计规范。正如术语保险丝所暗示的那样，这种连接类型的另一个优点是，在发生强烈地震事件后，损坏的板材可以相对容易地更换。这项拟议的研究将由两名硕士和两名博士生进行。第一个博士生将研究穿孔图案的几何排列和尺寸以及板材性能对连接属性的影响。第一个MSC项目将研究双向加载对穿孔板临界设计性能的影响。第二个MSC项目将研究需要应用于连接穿孔钢板和木材构件的连接部分的超强系数。这部分应过度设计，以防止木材材料的断裂，但目前没有可靠的指南来确定合适的过度设计系数。第二个博士论文项目将研究大量木结构体系的性能，如剪力墙，其中包括开发的穿孔板连接。这个项目的动机是与设计工程师进行讨论，他们已经确定了为高层木结构建筑提供经济可靠的连接系统的必要性。拟议项目的成功将使大量木材被认为是一种可行的、低碳足迹的结构材料，特别是在地震活跃地区。

Tall wood buildings are now technically feasible as a result of advancements made in the development of modern engineered wood products. One of the major concerns for tall wood buildings is their capacity to perform safely under seismic motions. Desirable performance attribute under seismic action is the ability of a structure to undergo large deformation, as a means to dissipate seismic energy, without collapse. For wood structures, this ability can only be accomplished if the connections in the structures contain metal components that act as a source of energy dissipation. An approach of using the so-called structural fuse to dissipate energy will be explored in this research program. This approach has been applied in steel structures, but application in wood structures will require further research. The proposed program expands on current research by the applicant to further develop a connection system that consists of a perforated steel plate connecting two or more timber members. The part connecting the steel plate to a timber member will be detailed with metal fasteners, and designed to be stronger than the perforated steel plate to ensure that the target energy dissipation would occur in the steel plate under seismic actions. The perforation pattern consists of a number of circular holes spaced at regular distance. This pattern would facilitate tuning of the perforated plate to achieve the desirable mechanical properties, such as strength, stiffness, ultimate displacement and energy dissipating capacity, and therefore the development of design specifications. As the term fuse implies, another advantage of this type of connection is that the damaged plate can be replaced with relative ease after a strong seismic event. The proposed research will be undertaken by two MSc and two PhD students. The first PhD student will investigate the influence of geometry arrangement and dimensions of perforation pattern and plate material properties on connection attributes. The first MSc project will investigate the influence of bi-directional loading on critical design properties of perforated plate. The second MSc project will study the over-strength factor that needs to be applied to the part of the connection that connects the perforated steel plate to the timber member. This part shall be over-designed to prevent fracture in wood material, but there is currently no reliable guidance on suitable over-design factor to be used. The second PhD thesis project will study the performance of the mass timber structural systems, such as shear walls, that incorporate the developed perforated plate connection. This project was motivated by discussion with design engineers who have identified the need to have economical and reliable connection systems for tall wood buildings. The success of the proposed project will allow mass timber to be considered as a viable, low carbon footprint structural material for structures, especially in seismic-active regions.