Collaborative Research: A Resilience-based Seismic Design Methodology for Tall Wood Buildings

随着美国城市社区人口的持续增长，对8至20层的高层住宅和混合用途建筑的需求不断增加。在这个高度范围内的建筑物通常用混凝土或钢材建造。最近一种新的木结构创新，被称为交叉层压木材（CLT），是在西欧开发的，现在正在世界各地实施，作为传统高层建筑结构材料的可持续和低碳足迹替代品。然而，高层CLT建筑的抗震设计方法尚未得到认可和验证，因此这些高层木结构建筑在美国的建设受到限制。这项研究将通过研究弹性高层木结构建筑的抗震设计方法来打破这一障碍，这些建筑可以在设计级地震后立即重新使用，并在大地震后迅速修复（与目前的建筑系统相比）。使用本项目开发的抗震设计方法，研究团队将与工程和建筑界的从业者合作，通过在理哈伊大学国家科学基金会（NSF）支持的自然灾害工程研究基础设施（NHERI）实验设施中进行全尺寸子装配系统测试，设计、建造并验证一座十层木结构建筑的性能。随后在加州大学圣地亚哥分校由美国国家科学基金会支持的NHERI室外振动台进行了全面测试。这项研究将促成一种新的可持续建筑做法，这种做法也具有成本竞争力，从而增加对工程木材生产的需求，为森林资源提供附加价值，并促进建筑和林业部门的就业增长。作为研究的一部分，实验项目将向公众和利益相关者提供与地震减灾、现代木材工程和弹性建筑概念有关的问题。本研究的目的是调查和验证一种结合高性能结构和非结构系统的高层木结构建筑的抗震设计方法。该方法将定量地说明建立弹性。这将通过在四年期间计划的一系列研究任务来完成。这些任务将包括高层木结构建筑的力学建模，包括几种后张摇摆CLT墙体系统，影响弹性的结构和非结构建筑构件的易碎性建模，建筑子装配系统的全尺寸双向测试，基于弹性的地震设计方法的开发，最后是一系列十层CLT建筑样本的全尺寸振动台测试，以验证所调查的设计。结构系统的调查将包括后张CLT摇摆墙在整体和部分摇摆配置。在一个完整的建筑系统中实施分段摇墙将是一个尚未实现物理的变革性概念。摇摆墙系统将在整体建筑行为的背景下进行研究，包括重力系统和非结构组件。研究小组将进一步推动现有的基于性能的抗震设计的边界，通过开发一种设计程序，明确考虑建筑在地震后恢复功能所需的时间。通过NHERI实验设施提供的大规模测试能力，设计方法将得到实验验证，同时将通过NHERI DesignSafe-ci.org数据仓库生成高层木结构建筑在动态载荷下的标志性数据集，这些数据集将提供给更广泛的研究和从业者社区。该项目将通过与太平洋西北地区对高层CLT建筑感兴趣的从业者紧密联系，促进这种新结构原型的实施，作为一种具有成本竞争力的设计选择。研究生和本科生，包括社区大学生，将积极参与这项研究并获得宝贵的知识和经验，这将使他们成为使用现代工程木材材料的可持续建筑实践的领导者。

As the U.S. population continues to grow in urban communities, the demand for tall residential and mixed-use buildings in the range of eight to twenty stories continues to increase. Buildings in this height range are commonly built using concrete or steel. A recent new timber structural innovation, known as cross laminated timber (CLT), was developed in western Europe and is now being implemented around the world as a sustainable and low carbon-footprint alternative to conventional structural materials for tall buildings. However, an accepted and validated design method for tall CLT buildings to resist earthquakes has not yet been developed, and therefore construction of these tall wood buildings in the United States has been limited. This research will break this barrier by investigating a seismic design methodology for resilient tall wood buildings that can be immediately re-occupied following a design level earthquake and quickly repaired (compared to current building systems) after a large earthquake. Using the seismic design methodology developed in this project, the research team will work with practitioners across the engineering and architectural communities to design, build, and validate the performance of a ten-story wood building by conducting full-scale sub-assembly system testing at the National Science Foundation (NSF)-supported Natural Hazards Engineering Research Infrastructure (NHERI) experimental facility at Lehigh University, followed by full-scale tests at the NSF-supported NHERI outdoor shake table at the University of California at San Diego. This research will enable a new sustainable construction practice that is also cost-competitive, thereby increasing demands for engineered wood production, providing added value for forest resources, and enhancing job growth in the construction and forestry sectors. As part of the research, the experimental programs will serve to provide outreach to the public and stakeholders on issues related to seismic hazard mitigation, modern timber engineering, and resilient building concepts.The goal of this research is to investigate and validate a seismic design methodology for tall wood buildings that incorporates high performance structural and non-structural systems. The methodology will quantitatively account for building resilience. This will be accomplished through a series of research tasks planned over a four-year period. These tasks will include mechanistic modeling of tall wood buildings with several variants of post-tensioned rocking CLT wall systems, fragility modeling of structural and non-structural building components that affect resilience, full-scale bi-directional testing of building sub-assembly systems, development of a resilience-based seismic design methodology, and finally a series of full-scale shake table tests of a ten-story CLT building specimen to validate the investigated design. The structural systems investigated will include post-tensioned CLT rocking walls in both monolithic and segmental rocking configurations. Implementing segmental rocking walls in a full building system will be a transformative concept that has yet to be realized physically. The rocking wall systems will be investigated under the context of holistic building behavior, including gravity systems and non-structural components. The research team will further push the boundary of existing performance-based seismic design by developing a design procedure that explicitly considers the time needed for the building to resume functionality after an earthquake. With the large-scale testing capacity provided by the NHERI experimental facilities, the design methodology will be experimentally validated, which will at the same time generate a landmark data set for tall wood buildings under dynamic loading that will be available to the broader research and practitioner community through the NHERI DesignSafe-ci.org Data Depot. The project will facilitate implementation of this new structural archetype by interfacing closely with practitioners in the Pacific Northwest interested in tall CLT buildings as a cost-competitive design option. Graduate and undergraduate students, including community college students, will actively participate in this research and gain valuable knowledge and experience, which will prepare them to become leaders in sustainable building practices using modern engineered wood materials.