ERI: Developing Ductility through Replaceable Concrete Anchorage Connections for Improved Seismic Performance of Mass Timber Structures

该工程研究启动奖(ERI)支持开发一种改进的抗震木材-混凝土连接的研究，该连接使用可更换的延性锚杆，用于地震后的快速修复。随着人们对美国的兴趣与日俱增，大型木结构建筑在世界建筑和建筑史上占有重要地位。为了满足易受地震危害地区的现代设计理念，大型木结构建筑的设计重点是通过连接中的损伤、延性和地震能量耗散来保持在大地震中的安全。然而，这些机制不可避免地会导致建筑物损坏，并影响震后建筑物的整体入住率、功能性和可维修性，最终影响社区的弹性。改进的木材-混凝土连接将减轻地震对木材结构组件的影响，并通过启用可靠的延性机制来耗散将木材组件连接到混凝土基座的锚杆中的能量，并允许在损坏后更换拉伸的锚杆，从而提高地震弹性。构件试验将调查木材-混凝土连接的抗震性能，数值研究将扩展这些发现，以评估其他设计参数，以制定适用于工程实践的设计建议和建模建议。研究活动将被纳入结构工程的课堂模块，并将通过外展计划让代表不足的群体参与工程。项目数据将被存档并在自然灾害工程研究基础设施(https://www.DesignSafe-ci.org).The)数据库中公开提供。在木材-混凝土连接中观察到的主要失效机制包括将钢板连接到木材组件的小直径紧固件的塑性变形和钢板本身的塑化，从而导致所附木材构件的损坏。改进的延性-锚杆连接侧重于锚杆变形的概念，以促进整体增强的结构坚固性、延性和强度，限制板材和连接的木质构件的损坏，并在地震后的情况下加快木结构建筑的修复。本项目的研究目标包括：(1)延性-锚杆节点的抗震性能及其修复后的剩余能力；(2)结构整体抗震需求与节点能力的分析方法。采用延性锚杆和可更换螺纹杆的木-混凝土节点原型进行了模拟抗震试验，研究了新的节点设计以及锚杆张拉长度对节点整体性能的影响。将使用实验验证的有限元分析来研究更广泛的连接配置的响应，为执业工程师提供设计和建模指南。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Engineering Research Initiation (ERI) award supports research to develop an improved seismic resistant timber-concrete connection using replaceable ductile-anchor rods for rapid post-earthquake repair. Of growing interest in the United States, mass timber buildings hold a relevant place in the history of world architecture and construction. To meet the modern design philosophy in regions vulnerable to seismic hazards, mass timber buildings are designed to remain safe during large earthquakes by focusing damage, ductility, and seismic energy dissipation in the connections. However, these mechanisms inevitably induce building damage and affect the overall building post-earthquake occupancy, functionality, and repairability, ultimately impacting community resiliency. The improved timber-concrete connection will mitigate the impact of seismic damage in timber structural components and enhance seismic resiliency by enabling a reliable ductile mechanism to dissipate energy in the anchor connecting timber components to the concrete footing and allowing replacement of the stretched anchor rod after damage. Component testing will investigate the seismic behavior of timber-concrete connections and a numerical study will expand these findings to evaluate additional design parameters toward the development of design suggestions and modeling recommendations suitable for engineering practice. The research activities will be incorporated into an in-class course module in structural engineering and will engage underrepresented groups in engineering through outreach programs. Project data will be archived and made publicly available in the Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-ci.org).The main mechanisms of failure observed in timber-concrete connections include plastic deformations of the small diameter fasteners connecting the steel plates to the timber component and plasticization of the steel plate itself, with consequent damage in the attached timber element. The improved ductile-anchor connection focuses on the concept of anchor deformation to promote overall enhanced structural robustness, ductility, and strength, limiting the damage in the plate and in the connected timber component and accelerating the repair of timber buildings in post-earthquake scenarios. The project research objectives include exploring (1) the seismic behavior of the ductile-anchor connection and its residual capacity after repair, and (2) analytical methods relating the overall structural seismic demand to the connection capacity. Simulated seismic tests of timber-concrete connection prototypes with ductile anchor and replaceable thread rod will be conducted to investigate the new connection design and the effect of anchor stretch length on the overall performance of the connection. The response of a broader range of connection configurations will be studied using experimentally validated finite-element analysis to inform design and modeling guidelines for practicing engineers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.