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- Title
Optical Sensor Developments for Measuring the Surface Strains in Prestressed Concrete Members.
- Authors
Wu, C.-H.; Zhao, W.; Beck, T.; Peterman, R.
- Abstract
Conventionally, transfer-length strain measurements are performed using mechanical gauges such as the Whittemore gauge, or demountable mechanical (DEMEC) strain gauges, and others devices using 'contact' measuring principles. These methods involve tedious surface preparation, and are also prone to significant human errors and inaccuracies. Furthermore, these mechanical sensors can only detect lateral displacements. This paper presents a new optical sensor of measuring prestress concrete surface strains. It makes use of the laser-speckle displacement that is detected by cross correlating the associated optical signals from a Charged-Coupled Device (CCD) sensor. The sensor was designed to be able to measure the surface displacement components without being affected by other surface motions that are generally present during the concrete detensioning process. Experiments were conducted on a compressed concrete beam and a real prestressed concrete member during the manufacturing process. The results from the optical strain sensor showed good consistency with contact measurements made by using both a foil strain gauge and a Whittemore gauge.
- Subjects
OPTICAL detectors; STRAIN gages; SURFACE gages; PRESTRESSED concrete beams; PRESTRESSED concrete; STRAINS &; stresses (Mechanics)
- Publication
Strain, 2011, Vol 47, pe376
- ISSN
0039-2103
- Publication type
Article
- DOI
10.1111/j.1475-1305.2009.00621.x