Standardization of Automated Crack Monitoring Apparatus for Long-Term Commercial Applications

Markian B. Petrina

doi:https://doi.org/10.21985/N2PR3F

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Standardization of Automated Crack Monitoring Apparatus for Long-Term Commercial Applications

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All structures have cosmetic cracks, which have no influence on structural integrity and usually remain unremarked until the structure’s occupants sense ground vibrations. Such vibrations are often associated with engineering activity, but are rarely responsible for cracks. However, this is difficult to prove without scientific basis. Automated Crack Monitoring (ACM) provides this basis by measuring crack displacement with micromeasurement instruments and data logging systems. Previous work (Louis, 2000; Siebert, 2000; McKenna, 2002; Snider, 2003) has shown that temperature and humidity effects far exceed those of typical engineering-induced ground motion by as much as an order of magnitude. Until recently, all ACM systems were considered research instruments. Though highly accurate, such apparatus was too unwieldy and expensive for widespread, commercially-viable installation. Simple, compact, and accurate ACM systems for commercial monitoring are necessary. Such apparatus would immensely benefit engineering reliant on ground vibration, by effectively demonstrating the relatively small contribution to wall crack opening and closing from engineering activity. This thesis proposes methods to qualify commercial ACM systems under controlled laboratory and field conditions. An alpha-model commercial ACM apparatus, System X, was tested and evaluated with these methods to verify their validity. Rigorous testing is crucial to ensuring ACM equipment will perform adequately and provide unassailable information in real-world situations fraught with legal and financial consequences. The methods of this thesis are the first step in developing a reliable and defensible validation process

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