FHWA NDE CENTER RESEARCH & DEVELOPMENT
Stress Measurement
A curved girder bridge research study is currently being conducted at the TFHRC. As part of this project a full-scale bridge has been erected and is being tested in the TFHRC structures laboratory. The
structure consists of three 90-foot long curved steel bridge girders that are joined together with several cross frames. These cross
frames were specifically designed for this project and are of a non-typical configuration.
Figure 1: A close-up view of the girder cross frames
Steel pipes with an outer diameter of about
4.5 inches are bolted together to make up these cross frames. Each end of the various sections of pipe is welded to a flange that
contains bolt holes for connection to the bridge girder. Installation of the cross frames between two girders is difficult due to
alignment problems. As a result, the cross frame members have to be forced into place. This installation process causes unwanted
stresses to be introduced into the cross frame members. As part of the bridge testing, a method to determine the amount of locked-in
stresses in these cross frames was desired. The Federal Highway Administration (FHWA) Nondestructive Evaluation (NDE) Center utilized ultrasonic stress measurement techniques and Barkhausen noise stress measurement
techniques to measure the cross frame stresses. Both methods have the potential to allow for quick, convenient measurements at
various points during the curved girder bridge testing.
Figure 2: Stress measurement techniques
in use on the structure.
For more information, please contact either by e-mail or telephone.
Frank Jalinoos (202) 493-3082
frank.jalinoos@fhwa.dot.gov
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