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.

在钢筋混凝土建筑物中，现场地板板或“隔膜”必须抵抗重力负载，结构和建筑物内容物的重量以及由风或地震期间地板的惯性引起的水平载荷。为了使建筑物运行，这些地板膜片还必须包含用于楼梯，电梯和机械系统的开口。尽管在设计重力负载的结构时，这些空缺的存在是考虑到这些空缺的，但对它们在地震负荷过程中如何影响建筑物行为的研究或了解很少。最近在五层钢筋混凝土建筑上进行了地震模拟试验期间，最近证明了这种缺乏理解的潜在后果。测试过程中意外的隔膜损伤表明，与墙壁和柱相邻的开口有助于塌陷风险，并且可能排除或延迟地震事件后建筑物功能的返回。这项灾难弹性研究补助金（DRRG）项目将对使用开口和开发其设计工具，并可能量化地震期间的预期性能，对现场混凝土隔膜的行为产生基本理解。这项研究将由在线课程流动完成，重点关注准确的模拟方法及其验证，对于学生和从业人员，作为最近建立的地震工程证书计划的一部分，以及宣传活动的一部分，并促进代表性不足的少数群体和第一代学生的研究。强度，用于抗倒​​塌和基于恢复的地震工程，可在现场混凝土隔膜带有开口。研究将研究（1）准确的负载路径，包括从低应力到支柱区域的扇形收集模式，这些模式构成了主要负载路径； （2）开口的影响和建立受保护区域以减轻可能导致部分崩溃的损害； （3）损害状态和脆弱曲线，量化diaphragm性能以纳入功能恢复方法。将回答一些基本的研究问题，包括（1）隔膜穿过的惯性负载路径是什么，以及这些负载路径如何受开口影响； （2）平板厚度，增强和开口的存在如何影响受复杂的平面内应力受到的隔膜元件的能力； （3）开口的存在如何改变隔膜的有效刚度，以及对工程需求参数的影响； （4）工程需求参数，地面运动强度度量和隔膜损伤之间的关系是什么？ （5）隔膜周围的隔膜损害如何影响安全性，故事访问和宗旨功能。同样重要的是，该项目将构成其他研究的基础，以使用伪动态和地震模拟器测试来充分调查横向抗力度系统，包括板墙和平板柱连接。该奖项反映了NSF的法定任务，并通过使用该基金会的知识优点和广泛影响来评估NSF的法定任务。