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Proceedings Paper

Bridge-safety evaluation using ultrasonic stress measurement
Author(s): Al V. Clark; Margarit G. Lozev; P. A. Fuchs
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Paper Abstract

Fracture mechanics can be used to evaluate the consequence of having a crack in a bridge structure. To do so requires that the stress state near the crack be known including the contribution of residual and fabrication stresses. In general these must be measured. Stress causes a small but measurable change in the speed of sound in many materials. Hence measurement of velocity in a bridge provides a means to determine all the components of stress. This concept has been demonstrated in laboratory situations by various researchers. Here we report results from field tests on actual bridges. The stress in flange and web regions of two bridges was measured with ultrasonics. In the first bridge we determined the residual stress in the girders. The second bridge was an integral backwall bridge with no expansion joints. It had been instrumented at time of construction. Strain gage readings indicated compressive stresses near yield. Ultrasonic measurements showed the bridge to be safe. Subsequent replacement of suspect electronics in the monitoring instrumentation verified the ultrasonic results to be safe.

Paper Details

Date Published: 13 November 1996
PDF: 7 pages
Proc. SPIE 2946, Nondestructive Evaluation of Bridges and Highways, (13 November 1996); doi: 10.1117/12.259153
Show Author Affiliations
Al V. Clark, National Institute of Standards and Technology (United States)
Margarit G. Lozev, Virginia Transportation Research Council (United States)
P. A. Fuchs, West Virginia Univ. (United States)

Published in SPIE Proceedings Vol. 2946:
Nondestructive Evaluation of Bridges and Highways
Steven B. Chase, Editor(s)

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