Crack Response of a Historic Structure to Weather Effects and Construction VibrationsPublic Deposited
Cosmetic cracks are very common in structures, and most of the time they remain unnoticed and do not decrease the structural integrity. Although these cracks are unremarkable and barely noticeable, occupants become concerned about these cracks when construction occurs nearby. In order to investigate the true nature of these cracks, the Automated Crack Monitoring (ACM) was developed. It allows the simultaneous measurement of crack responses to environmental changes and vibrations induced by various construction activities. While vibration environment is defined by seismological transducers, the ACM dual-purpose crack displacement sensors measure crack response. This thesis involves an ACM study to compare construction vibration, human household activity and long-term weather effects on a historical building in downtown Washington DC. Measurements and analysis show that construction activity in the vicinity of the structure did not create significant ground motion; long-term environmental crack displacement was 20 to 60 times greater than that caused by the largest measured construction-induced ground motion; crack displacements produced by occupant activity were larger than the largest construction vibration-induced crack displacement by a factor of 2 to 16, but smaller than the long-term environmental or weather induced crack displacement; and exterior cracks experienced larger weather induced displacements than either of the two interior cracks.
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