Advancing Earthquake Engineering of Cast-in-Place Concrete Diaphragms with Openings

推进带开口现浇混凝土隔膜的抗震工程

• 批准号: 2242605
• 负责人: Travis Thonstad
• 金额: $ 40万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2242605&HistoricalAwards=false
• 关键词: Advancing; Earthquake; Engineering; Cast; Place

In reinforced concrete buildings, cast-in-place floor slabs, or “diaphragms”, must resist both gravity loads, the weight of the structure and building contents, and horizontal loads, caused by wind or the inertia of the floors during earthquakes. For the building to function, these floor diaphragms also must contain openings for stairs, elevators, and mechanical systems. Although the presence of these openings is accounted for when designing the structure for gravity loads, there is little research or understanding of how they affect the building’s behavior during earthquake loading. The potential consequences of this lack of understanding were recently demonstrated during earthquake simulator tests on a five-story reinforced concrete building. Unexpected diaphragm damage during testing indicates that openings adjacent to walls and columns contribute to collapse risk and could preclude or delay the return of a building’s functionality after a seismic event. This Disaster Resilience Research Grants (DRRG) project will develop a fundamental understanding of the behavior of cast-in-place concrete diaphragms with openings and develop tools for their design and for probabilistically quantifying their expected performance during an earthquake. The research will be complemented by an online class curriculum focusing on accurate simulation approaches and their validation, for both students and practitioners, as part of the recently established earthquake engineering certificate program and outreach to engage underrepresented minority and first-generation college students in research.This award will focus on advancing science-based tools and technologies, through simulation-driven experimental testing and nonlinear finite element analysis of prototype buildings under multiple hazard intensities, for the collapse-resistant and recovery-based earthquake engineering of cast-in-place concrete diaphragms with openings. This research will investigate (1) accurate load paths, including fanned collection patterns from regions of low stress to struts, which form the primary load path; (2) the impact of openings and establishing protected zones to mitigate damage that could lead to partial collapse; and (3) damage states and fragility curves that quantify diaphragm performance for inclusion in functional recovery methodologies. Several fundamental research questions will be answered, including (1) what is the inertial load path through the diaphragm, and how are these load paths affected by openings; (2) how does the slab thickness, reinforcement, and the presence of openings affect the capacity of diaphragm elements subjected to complex in-plane stresses; (3) how does the presence of openings modify the effective stiffness of diaphragms, and what is the effect on engineering demand parameters; (4) what is the relationship between engineering demand parameters, ground motion intensity measures, and diaphragm damage; and (5) how does diaphragm damage around openings affect safety, story access, and tenet functionality. Equally important, this project will form the foundation for additional research to fully investigate the lateral force resisting system, including slab-wall and slab-column connections, using pseudo-dynamic and earthquake simulator testing.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.

在钢筋混凝土建筑中，现浇楼板或“隔板”必须能够抵抗重力荷载（结构和建筑内容物的重量）以及由风或地震期间地板惯性引起的水平荷载。为了使建筑物正常运行，这些地板隔板还必须包含楼梯、电梯和机械系统的开口。尽管在设计重力荷载结构时考虑了这些开口的存在，但很少有研究或了解它们在地震荷载期间如何影响建筑物的行为。最近在一座五层钢筋混凝土建筑上进行的地震模拟器测试中证明了这种缺乏了解的潜在后果。测试过程中意外的隔膜损坏表明，墙壁和柱子附近的开口会增加倒塌风险，并可能妨碍或延迟地震事件后建筑物功能的恢复。该抗灾研究补助金 (DRRG) 项目将对带开口的现浇混凝土隔板的行为有一个基本的了解，并为其设计和概率量化其在地震期间的预期性能开发工具。该研究将辅以在线课程课程，重点关注学生和从业人员的精确模拟方法及其验证，作为最近设立的地震工程证书计划和推广活动的一部分，以吸引代表性不足的少数族裔和第一代大学生参与研究。该奖项将侧重于通过模拟驱动的实验测试和多重灾害下原型建筑的非线性有限元分析来推进基于科学的工具和技术 强度，用于带开口的现浇混凝土隔板的抗倒塌和基于恢复的地震工程。本研究将研究（1）准确的载荷路径，包括从低应力区域到支柱的扇形收集模式，形成主要载荷路径； (2) 开口和建立保护区的影响，以减轻可能导致部分倒塌的损害； (3) 损伤状态和脆性曲线，用于量化隔膜性能以纳入功能恢复方法。将回答几个基本研究问题，包括（1）穿过膜片的惯性载荷路径是什么，以及这些载荷路径如何受到开口的影响； (2) 楼板厚度、配筋和开口的存在如何影响隔膜单元承受复杂面内应力的能力； (3) 开口的存在如何改变隔板的有效刚度，以及对工程需求参数有何影响； （4）工程需求参数、地震动烈度测量与隔板损伤之间的关系如何； (5) 开口周围的隔膜损坏如何影响安全性、楼层通道和宗旨功能。同样重要的是，该项目将为进一步研究奠定基础，以利用伪动力和地震模拟器测试全面研究侧向力抵抗系统，包括板墙和板柱连接。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。