EAGER: Informing Infrastructure Decisions through Large-Amplitude Forced Vibration Testing

美国老化的民用基础设施带来的社会问题无处不在--渗透到与我们的防洪系统、现有建筑存量和交通网络相关的各种结构中。认识到这类系统在自然和人为危害下构成的生命安全风险，人们非常重视开发可靠的安全评估方法，以支持它们的管理、适应和再利用。最初几乎完全依赖于视觉检查和简化的模拟模型，在过去的几十年里已经发展到现在可以使用的令人印象深刻的一系列传感技术、高度精炼的模拟模型和模型校准技术。虽然这些进步是显著的，但仍然没有一种方法能够可靠地评估结构和基础系统的安全性。这个早期概念的探索性研究资助(AGIRE)项目的目的是通过使用最初设想用于评估土壤特性的大振幅振动器来克服这一障碍。如果这些大型振动器的重新调整用途被证明是成功的，这项研究将消除我们预测现有基础设施系统的使用寿命并进而就其适应和重新使用做出合理决策的能力的一个关键障碍。除了这一技术贡献，这项研究还将(通过开发和实施基于竞争的外展工作)暴露和吸引高中生学习工程学，并将通过罗格斯大学正在进行的一系列项目从传统上代表性较低的群体中招收研究生(他们将得到项目资金的支持)。该项目旨在克服现有结构系统动态测试方法的局限性。虽然存在具有成本效益的方法，但它们依赖于低幅度的单向激励，无法克服间歇性粘滑机制或在下部结构-基础系统内引起明显的反应。因此，为了以受控的方式克服这些低水平机制，并提高由此产生的安全评估的可靠性，研究团队将使用NSF NHERI计划提供的大振幅移动振动器。虽然这种振动器最初设想用于与岩土工程地震相关的研究，但它为推动结构-基础系统超越其低层响应而提供了机会，以揭示更能代表安全极限状态下预期行为的性能特征。通过克服只存在于低水平的机制，将捕捉到更真实的力分布，这将极大地提高与材料非线性开始(包括载荷水平和空间位置)相关的模拟模型预测的可靠性。为了实现这一总体目标，将追求以下更有针对性的目标：(1)开发、评估和改进一系列强迫振动测试和控制策略，以捕获指示下部结构/基础和上部结构系统关键性能属性的响应测量。(2)开发、评估和改进一系列用于结构系统(基础-子结构-上部结构)识别和评估的非模型和基于模型的数据解释框架。(3)对已知子结构、基础和土壤特性的运行结构进行测试/控制策略和数据解释框架的验证

The societal problems presented by aging civil infrastructures in the US are pervasive - cutting across diverse structures associated with our flood protection systems, existing building stock, and transportation networks. In recognition of the life safety risks posed by such systems under natural and anthropogenic hazards, there has been significant attention paid to the development of reliable safety assessment approaches to support their management, adaption, and reuse. What began with a near-exclusive reliance on visual inspections and simplified simulation models has evolved over the last several decades to embrace the impressive array of sensing technologies, highly refined simulation models, and model calibration techniques now available. Although these advances are significant, there remains no approach capable of assessing the safety of both the structure and the foundation system in a reliable manner. The aim of this EArly-concept Grant for Exploratory Research (EAGER) project is to overcome this barrier through the use of large amplitude shakers that were originally envisioned for evaluating soil properties. If this re-purposing of these large shakers proves successful, this research will remove a critical barrier to our ability to forecast the service life of existing infrastructure systems and, in turn, to make sound decisions about their adaption and reuse. In addition to this technical contribution, this research will expose and attract high schools students to engineering (through the development and implementation of a competition based outreach effort) and will recruit graduate students (who will be supported through project funds) from traditionally underrepresented groups through a host of on-going programs at Rutgers University. The project aims overcoming limitations of existing dynamic testing methodologies for structural systems. While cost-effective methodologies exist, they suffer from a reliance on low-amplitude, uni-directional excitation, which is unable to overcome intermittent stick-slip mechanisms or to induce appreciable responses within the substructure-foundation system. Therefore, to overcome these low-level mechanisms in a controlled manner, and improve the reliability of the resulting safety assessment, the research team will use large-amplitude mobile shakers that are available through the NSF NHERI Program. Although originally envisioned for geotechnical engineering seismic-related research, such shakers open opportunities for pushing the structural-foundation system beyond their low-level responses to reveal performance characteristics that are more representative of the expected behavior under safety limit states. By overcoming the mechanisms that exist only at low-levels, a more realistic distribution of forces will be captured, which will greatly enhance the reliability of simulation model predictions associated with the onset (both load levels and spatial location) of material nonlinearity. To meet this overarching goal, the following more focused objectives will be pursued:(1) Develop, evaluate, and refine a series of forced vibration testing and control strategies to capture response measurements indicative of key performance attributes of substructure/foundation and superstructure systems.(2) Develop, evaluate, and refine a series of both model-free and model-based data interpretation frameworks for structural system (foundation-substructure-superstructure) identification and assessment.(3) Perform a validation of the testing/control strategies and data interpretation frameworks on an operating structure with known substructure, foundation, and soil characteristics