Performance of mid-ply wood shear walls with openings

受强烈地震或强风影响地区对强大的抗侧载系统需求不断增长的驱动，中层剪力墙于20世纪90年代在加拿大首次开发出来。测试表明，中层剪力墙的横向承载力大约是传统木材剪力墙的两到三倍。2014年，加拿大木材设计标准CSA O86首次实施了中层剪力墙系统的设计规定。随着业主越来越喜欢开放空间的概念和大型玻璃幕墙，结构剪力墙和大开口较少，坚固的中层剪力墙近年进一步引起设计师的注意。这是一种全球趋势，正在北美以及进口加拿大木制品用于建筑的海外国家发生。近年来，木材建筑的允许建筑高度从低层（最多4层）增加到中层（6层），这导致人们对这种坚固的木材剪力墙的兴趣增加，以解决更高的设计荷载，特别是在中层建筑的低层。在这种情况下，最近提出了一个关键问题，即关于开口对中厚墙的刚度和强度特性的影响，这通常是门窗所必需的。本项目旨在解决这一问题。具体目标是围绕中厚墙的开口制定框架细节，以尽量减少开口对组件强度和刚度的影响，并评估开口的相对尺寸和位置对中厚墙强度和刚度的影响。这项研究将导致设计指南，以解决带开口的中层墙，以及围绕开口的施工细节，这将使带开口的中层墙段保持可接受的刚度和强度水平。拟议研究的成功将有助于增加加拿大木材和人造板在国内和海外市场的使用。

Driven by the growing demand on strong lateral load resisting systems in regions susceptible to severe earthquakes or strong winds, the mid-ply shear wall was first developed in the 1990s in Canada. Testing has shown that mid-ply walls possess approximately two to three times the lateral capacity of conventional wood shear walls. Design provision for mid-ply shear wall systems was implemented first time in Canadian timber design standard CSA O86 in 2014. As home owners increasingly favour an open space concept and large glass façades with few structural shear walls and large openings, the strong mid-ply shear wall has further attracted the attention of designers in recent years. This is a global trend that is happening in North America as well as overseas countries that import Canadian wood products for construction. The increase of allowable building height for wood construction from low-rise (upto 4 storesy) to mid-rise (6-storey) in recent years has led to increased interest in this strong wood shear wall to address the higher design loads, especially in the lower storey of mid-rise buildings. In this context, a key question has been raised recently regarding the effects of openings, which are often required for windows and doors, on stiffness and strength properties of mid-ply walls. This project is intended to address this issue. The specific objectives are to develop framing details around an opening in mid-ply walls to minimize the impact of the opening on the strength and stiffness of the assembly and to evaluate the influence of relative size and location of an opening on the strength and stiffness of a mid-ply wall. This research will lead to design guidelines to address mid-ply walls with openings as well as construction detailing around openings that would allow segments of mid-ply walls with openings to retain an acceptable level of stiffness and strength. The success of the proposed research will help to increase the use of Canadian lumber and wood-based panels domestically as well as in overseas markets.