FHWA NDE CENTER RESEARCH & DEVELOPMENT
FHWA Curved Girder Bridge Study
A curved girder bridge research program 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.
 |
Figure1: The full-scale bridge test structure in the lab |
The FHWA NDE Center laser system has been used to perform two main types of measurements on the curved girder bridge during the course of
testing. The first measurement was of the global deflection and rotation of the entire 90-foot long three-girder bridge during
testing. This measurement was accomplished with the use of 124 ½" diameter targets fixtured to the bridge girders. The use
of the ½" targets allows an exact point on the structure to be tracked as the structure moves.
The second type of measurement was a detailed surface scan of a section of the curved girder bridge. During testing a 30-foot
section in the middle of one of the bridge girders was loaded until failure. Of particular interest to the curved girder bridge
researchers was the initial failure mode of this component specimen. Therefore, the laser system was used to make a detailed
scan of the web and top flange of the component specimen at various load steps during testing. This scan covered a length of
about 16 feet of the 16-inch wide top flange and a length of about 16 feet and a height of 2.5 feet of the web. The goal of the
measurements was to determine the out-of-plane distortions of the web and top flange. Resolution tests show that the laser
system can resolve out-of-plane distortions of 0.04 inches or greater in this application.
 |
Figure 2: The laser as mounted for testing |
Tools were developed to post process the laser data immediately after data collection and produce plots representing the
component out-of-plane distortions. The locations on the component top flange and web where the failure was to occur could be
identified with the laser system prior to any visible indications in these areas.
Figure 3: The laser system being used to make detailed scans of the girder
Post processing algorithms, seen below, produce plots showing the out-of-plane distortions of the specimen web during testing. In the plot color is proportional to the magnitude of out-of-plane movement and shows the web deforming as load is applied to the test bridge.
Please contact Dr. Paul Fuchs
by email or by telephone at (202) 493-3095 for More Information.
Other applications of the FHWA NDE Center Laser System:
Bridge Load Testing
Steel Bridge Fabrication
GRS Abutments
Back to the Top
