ABSTRACT

Detection of structural damage is an important issue. Some techniques require knowledge of the undamaged state or in-depth knowledge of the construction materials used. The application of principal component analysis to the temporal variation in natural frequencies is a promising technique. With an undamaged structure a single principal component will suffice to explain the change in modal frequencies with weather variables, whereas more components are needed in the case of damaged structures. Like all other detection techniques, it has advantages and drawbacks. The main advantages are the ability to work without knowledge of the previous state of the structure, the relatively short monitoring time required (about 10 days), low cost, and low number of instrumentations. The main drawback is the need for more studies to correlate degree of damage with the number of principal components. This paper presents the results obtained for six structures: Mallorca Cathedral, four university buildings in Barcelona, and a reduced model structure in a laboratory. We also propose a semiautomatic algorithm to track modal frequencies over time and add a discussion of operational modal analysis in real buildings.

摘要

检测结构损坏是一个重要的问题。一些技术需要了解未损坏状态或深入了解所使用的建筑材料。将主成分分析应用于自然频率的时间变化是一种很有前途的技术。对于未损坏的结构，单个主成分就足以说明模态频率随天气变量的变化，而在损坏的结构中需要更多的成分。像所有其他检测技术一样，它也有优点和缺点。主要优点是无需了解结构的先前状态即可工作，所需的监视时间相对较短（约10天），成本低且仪器数量少。主要缺点是需要进行更多的研究以将破坏程度与主要成分的数量相关联。本文介绍了六种结构所获得的结果：马略卡大教堂，巴塞罗那的四所大学建筑以及实验室中的简化模型结构。我们还提出了一种半自动算法来跟踪随时间变化的模态频率，并增加了对实际建筑物中运行模态分析的讨论。