Experimental Study on Damage Identification of Dynamically Excited Structures

动态激励结构损伤识别实验研究

• 批准号: 0533223
• 负责人: Surot Thangjitham
• 金额: --
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0533223&HistoricalAwards=false
• 关键词: Experimental; Study; Damage; Identification; Dynamically

AbstractThere is an increasing interest in the vibration data-based detection, localization, andquantification of damage in civil engineering structures exposed to earthquake, wind, and otherloads. Early motivation for this was provided by the discovery of hidden damages in steelstructures caused by the 1994 Northridge and 1995 Great Hanshin (Kobe) Earthquakes, and alsoby the fact that structural element are usually inaccessible after construction. Several analyticalmethods have been proposed in the literature and still more are being developed for this.Currently simulated data are being used to check the effectiveness of these methods; however,their validation and comparison on actual experimentally obtained data is yet to be done.In this exploratory project, it is proposed to experimentally study and validate theeffectives of the autoregressive with exogenous input model, wavelet transform, eigensystemrealization algorithms (ERA), and subspace identification (SSI) approaches for comprehensivemodal and damage identification of civil engineering structures. For damage localization andquantification the flexibility and rotational flexibility matrices with and without and damage locatingvectors will be used. Further analytical improvements in these methods will also be made formore reliable damage quantification. The tests will be conducted on a scaled three-story, ninedegrees-of-freedom structure model prepared such that its stiffness properties can be changedby planned changes in one or more braces, by sudden removal of one or two braces in real-timeusing magneto-rheological dampers, and by loosening the connecting hardware at few selectedjoints. The major cost of preparing this changeable scaled model will be borne by the PIsinstitution. The scaled model will be excited at its base by the 5' by 5' shaking table at VirginiaTech. The model would also have the capability of being excited by shakers installed at any ofthe three levels. The dynamic measurements of the acceleration response will be made usingten accelerometers, three placed at each floor level in two orthogonal directions plus one on thetable.The SGER funding is being sought to identify validated damage localization andquantification methods which will be needed in a more comprehensive follow-up study. Thisfollow-up study to be proposed later will develop an integrated system consisting of the validateddamage identification techniques with online consequence prognosis followed by onlineactuation, if necessary, of a control system to maintain the performance of the structure at anacceptable level. The successful outcome of this exploratory work will also be a very useful toolfor direct practical implementation in structural diagnostics and health monitoring.The Intellectual merit of this study is in the development of experimentally verifieddamage identification (detection, localization, and quantification) schemes for a comprehensivestructural health monitoring.Broader impacts of this research will occur at two levels: theeducation and training of graduate and undergraduate students and the availability of a muchneeded tool and data to researchers and practitioners involved in structural health monitoring. Agraduate student and an undergraduate student will work on this project. The undergraduatestudent will be supported through the REU program. She/he will be selected through the Centerfor the Enhancement of Engineering Diversity (CEED) at Virginia Tech from the pool of availableAfrican American, Hispanic, American Indian, and women students. The dissemination ofinformation and data generated in this research to other students, researchers and practitionerswill be done through class room teaching, website creation, presentations in conferences, andpublications in archival journals and conference proceedings.

摘要：人们对暴露于地震、风和其他荷载的土木工程结构中基于振动数据的损坏检测、定位和量化越来越感兴趣。这样做的早期动机是由于发现了 1994 年北岭地震和 1995 年阪神大地震造成的钢结构隐藏损坏，以及结构构件在施工后通常无法接近的事实。文献中已经提出了几种分析方法，并且正在为此开发更多的分析方法。目前正在使用模拟数据来检查这些方法的有效性；然而，它们对实际实验获得的数据的验证和比较还有待完成。在这个探索性项目中，建议通过外生输入模型、小波变换、特征系统实现算法（ERA）和子空间来实验研究和验证自回归的有效性用于土木工程结构综合模态和损伤识别的识别（SSI）方法。对于损伤定位和量化，将使用具有和不具有损伤定位向量的柔度和旋转柔度矩阵。还将对这些方法进行进一步的分析改进，以实现更可靠的损伤量化。测试将在一个按比例缩放的三层、九自由度结构模型上进行，该模型已准备好，可以通过计划改变一个或多个支撑、通过使用磁力实时突然移除一个或两个支撑来改变其刚度特性。流变阻尼器，并松开几个选定接头处的连接硬件。准备这个可变比例模型的主要费用将由 PI 机构承担。弗吉尼亚理工大学 5 英尺 x 5 英尺的振动台将在其底座上激发该比例模型。该模型还能够通过安装在三个级别中任意一个的激振器进行激励。加速度响应的动态测量将使用十个加速度计进行，其中三个加速度计放置在每个楼层的两个正交方向上，再加上一个放在桌子上。SGER 资金正在寻求确定经过验证的损伤定位和量化方法，这将需要在更全面的跟踪中向上学习。稍后提出的后续研究将开发一个集成系统，该系统由经过验证的损伤识别技术和在线后果预测组成，如有必要，还可以在线启动控制系统，以将结构的性能保持在可接受的水平。这项探索性工作的成功成果也将成为结构诊断和健康监测直接实际实施的非常有用的工具。这项研究的智力价值在于开发了经过实验验证的损伤识别（检测、定位和量化）方案，用于全面的结构诊断。这项研究的更广泛影响将发生在两个层面：研究生和本科生的教育和培训，以及为参与结构健康监测的研究人员和从业人员提供急需的工具和数据。一名研究生和一名本科生将参与该项目。本科生将通过 REU 计划获得支持。她/他将通过弗吉尼亚理工大学工程多样性增强中心 (CEED) 从非裔美国人、西班牙裔、美洲印第安人和女学生中选拔。本研究中产生的信息和数据向其他学生、研究人员和从业人员的传播将通过课堂教学、网站创建、会议演示以及档案期刊和会议记录中的出版物来完成。