Control of construction vibrations with an autonomous crack comparometer

Concern over construction vibration-induced craclcing has led to development of a new approach to vibration monitoring, an autonomaus crack comparometer (ACC). This paper describes sensor performance and chronicles the first steps in the development of this concept, illustrated in Figure 1. A single sensor measures both weather-induced micrometer changes in crack width and those produced by habitation and ground motion-induced vibration. This comparison is displayed in real time via the Internet without human interaction. Measurements reported herein show that weather-induced response of cracks is greater than that caused by presently allowable construction-induced vibration. Graphie display through the Internet more convincingly compares these differing responses. Visual comparison avoids the abstract complexity of vibration time histories and required belief of past comparisons of vibration Ievels with crack initiation. Finally, the Internet provides a mechanism of direct public participation in data collection and interpretation.