NEESR-CR: Design of Soil and Structure Compatible Yielding to Improve System Performance

NEESR-CR：土壤和结构兼容产量设计以提高系统性能

• 批准号: 0936503
• 负责人: Bruce Kutter
• 金额: $ 78.2万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0936503&HistoricalAwards=false
• 关键词: NEESR; CR; Design; Soil; Structure

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This award is an outcome of the NSF 09-524 program solicitation ''George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)'' competition and includes the University of California, Davis (lead institution) and Santa Clara University (subaward), and the University of California, San Diego (subaward). This project will utilize the NEES equipment site at the University of California, Davis.Hundreds of billions of dollars and thousands of lives are at risk when a major earthquake shakes a metropolitan area. Building damage or collapse is one of the primary contributors to the risk. Huge investments are being made to improve performance of new and old structures by including structural or mechanical energy dissipation devices such as dampers (huge shock absorbers) and even complex computer controlled actuators to counteract effects of earthquake shaking. Geotechnical and structural engineers, however, generally understand that a lot of the damaging shaking energy can be effectively dissipated just by allowing the foundations to absorb the energy. Energy that would otherwise damage a building can be dissipated through friction at the soil-foundation interface as well as by radiation back into the ground. Civil engineers understand this today, but they are reluctant to design buildings with foundations that rock (just a little) due to: (i) the understandable perception that geotechnical material properties are less certain than structural material properties and (ii) the partition between structural and geotechnical responsibility in our traditional engineering design process. (Presently, structural engineers design the part of the building above the ground and geotechnical engineers design the foundations, and there is minimal interaction between the two.)While it is clear that the bearing capacity of shallow foundations is very sensitive to uncertain soil properties, the moment capacity of typical shallow foundations is much more predictable than the bearing capacity. Rocking has the added benefit of introducing a natural self-centering tendency; imagine tilting a refrigerator a few degrees, and then letting go ? the refrigerator will rock back and forth a little, but it will eventually end up standing vertical (this is what we mean by ?self-centering?. Geotechnical and structural engineers would need to work together to ensure that rocking movement of a foundation, for example, is compatible with the movement of the rest of the building. This work will bring together leaders in structural and geotechnical engineering from universities and private engineering firms to figure out how to perform the collaborative holistic building design that allows us to design buildings that can move with a rocking foundation and hence allow us to take advantage of cost effective energy dissipation in the foundation. A strong technology transfer team that includes practicing engineers will work with the academics in this project to help ensure that innovative concepts are not impractical. Teaming with construction and practicing engineers actively involved in building code revision will also help speed our results toward adoption by the profession.Avoiding over-designed, over-conservative footings and reducing requirements for energy dissipation mechanisms within the superstructure will save construction costs and can improve performance. There is almost no experimental data available to indicate how rocking foundations will dynamically interact with a yielding structural system. This proposal will fill this gap by performing experiments on a NEES centrifuge facility. Computer simulations validated by experiments will be used to generalize findings over a larger range of prototype situations. Although our work focuses on buildings, the use of inelastic soil-foundation behavior incorporating energy dissipating and self-centering is applicable to a large array of bridges, towers, and taller buildings. Improved performance will lead to a reduction in economic and human losses associated with earthquakes. An effort to recruit new engineers by inviting groups of students in MESA (an organization that helps educationally disadvantaged students succeed in Math, Engineering, and Science) programs at local community colleges learn about civil engineering will help grow a diverse engineering workforce. Data from this project will be archived and made available to the public through the NEES data repository.

该奖项根据 2009 年《美国复苏和再投资法案》（公法 111-5）提供资金。该奖项是 NSF 09-524 计划征集“乔治 E. 布朗地震工程模拟网络 (NEES)”的结果）研究（NEESR）”竞赛，包括加州大学戴维斯分校（牵头机构）和圣克拉拉大学（子奖项）以及加州大学圣地亚哥分校（下级）。 该项目将利用加州大学戴维斯分校的 NEES 设备现场。当大地震袭击大都市地区时，数千亿美元的资金和数千人的生命将面临风险。 建筑物损坏或倒塌是造成风险的主要原因之一。 为了提高新旧结构的性能，人们进行了大量投资，包括结构或机械能量耗散装置，例如阻尼器（大型减震器），甚至复杂的计算机控制执行器，以抵消地震震动的影响。 然而，岩土和结构工程师普遍认为，只需让地基吸收能量，就能有效消散许多破坏性的震动能量。 原本会损坏建筑物的能量可以通过土壤-地基界面的摩擦以及辐射回地面来消散。 今天的土木工程师明白这一点，但他们不愿意设计地基有晃动（只有一点点）的建筑物，因为：（i）岩土材料特性不如结构材料特性那么确定的看法是可以理解的，以及（ii）结构之间的划分以及我们传统工程设计过程中的岩土工程责任。 （目前，结构工程师设计建筑物的地上部分，岩土工程师设计地基，两者之间的相互作用很小。）虽然很明显，浅基础的承载力对不确定的土壤特性非常敏感，典型浅基础的弯矩承载力比承载力更容易预测。 摇摆还有一个额外的好处，那就是引入自然的自我中心倾向；想象一下将冰箱倾斜几度，然后松开？冰箱会稍微前后摇晃，但最终会垂直站立（这就是我们所说的“自动定心”的意思。岩土工程师和结构工程师需要共同努力，以确保基础的摇晃运动，对于例如，与建筑物其余部分的运动兼容，这项工作将汇集来自大学和私人工程公司的结构和岩土工程领域的领导者，以找出如何进行协作的整体建筑设计，使我们能够设计出可以的建筑。随着基础的摇动而移动，因此使我们能够利用基础中具有成本效益的能量耗散。包括实践工程师在内的强大技术转让团队将与该项目中的学者合作，以帮助确保创新概念与积极参与的建筑和实践工程师合作。建筑规范的修订也将有助于加快我们的成果被行业采用。避免过度设计、过度保守的基础并减少上部结构内能量耗散机制的要求将节省建筑成本并提高性能。 几乎没有实验数据可以表明摇摆基础如何与屈服结构系统动态相互作用。 该提案将通过在 NEES 离心机设施上进行实验来填补这一空白。 通过实验验证的计算机模拟将用于概括更大范围的原型情况的发现。尽管我们的工作重点是建筑物，但结合能量耗散和自定心的非弹性土壤基础行为的使用适用于大量桥梁、塔楼和高层建筑。 性能的提高将减少与地震相关的经济和人员损失。 通过邀请当地社区大学 MESA（一个帮助教育弱势学生在数学、工程和科学方面取得成功的组织）项目的学生群体学习土木工程来招募新工程师，这将有助于培养多元化的工程队伍。 该项目的数据将被存档并通过 NEES 数据存储库向公众开放。