FRP Library

Kansas Division Documentation Report: Testing Of Large FRP Beam

1. Principal Contacts / Attendees

   Kansas Structural Composites, Inc., Kansas State University (K-State), University of Kansas, Kansas Department of Transportation and the Federal Highway Administration.

2. Discussion

   A large FRP beam was fabricated for the New York Department of Transportation. While the beam was being transported from Kansas to New York, a forklift damaged it. The bottom skin of the beam was pulled away from the core in about a ten-foot area. A new beam was fabricated and sent to New York for their testing. The damaged beam was taken to K-State to be tested in its damaged condition. The damaged beam was then repaired and retested. The repaired beam test is what we witnessed last Thursday.

   The beam is 1.0' wide x 32' long x 31.5" high. It was designed for HS-25 @ 4,000 #/ft. The beam is instrumented with strain gauges and acoustic emission sensors. The beam in New York failed at about 75,000 pounds. The damaged section failed at about 40,000 pounds. The failure typically occurs at the interface between the core and the top and bottom skins. During the repair a three-inch skirt was wrapped around the corners of the beam. The test first exceeded the capacity of the load cells that were being used to measure the load. Then the hydraulic cylinders reached the end of their stroke. They had to be raised up and spacers were added between the cylinders and the beam. Eventually the beam failed. The skin separated from the core ripping the skirt for about ¾ the length of the beam. The final load will have to be calculated based on the results from the strain gauges and deflections. At the end of the test it was estimated that the load was well over 100,000 pounds. About 1/10th of an inch of material was added during the repair of the skin. It is believed that wrapping a few sheets of fiberglass over the edge and creating the skirt greatly increased the capacity of the beam. The test results show the great strength of this material as well as showing that the material can be repaired without sacrificing that strength.