One of the most heavily used forests in the south is the Daniel Boone National Forest in Bath County in Kentucky, which receives more than 5 million visitors per year. A high-tech link to a key hiking trail in the county has been unknowingly used by visitors for more than 20 years.
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Connecting the Clear Creek Furnace Picnic Area with the Sheltower Trace Trail is the 60’clear span bridge, which was the first hybrid fiber reinforced composite I-girder bridge. A Strongwell-pultruded FRP hybrid composite I-beam (24" x 7-½" x ¾") provides the main load carrying members.
Bending stiffness is substantially increased with the addition of carbon fibers to the I-beam flanges. With the addition of carbon fibers, the modulus of elasticity is increased to 6.0 x 106 psi, compared to 2.8 x 106 psi if the FRP beam is used without the fibers.
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Technical Details
Strongwell-Chatfield supplied the pultruded grating, which was used for the walkway and fiberglass sucker rods. The sucker rods were produced at Strongwell-Bristol and they were anchored to the abutment for post tensioning. The design of the bridge is in conformance with AASHTO “Standard Specifications of Pedestrian Bridges,” with allowable deflection of L/180 (4 inches over 60 feet) at live loads of 85 psf.
| Technical Data |
| Product |
Hybrid Fiber Reinforced Composite Pedestrian Bridge |
| Process |
Pultrusion, Fiberglass Fabrication |
| Materials |
Carbon and fiberglass reinforced vinyl ester (carbon fibers in top and bottom flanges of the beam) |
| Sizes |
Total Bridge: 6 ft. wide by 60 ft. long
Hybrid Support Beams: 24” x 7-½” x ¾” |
| For |
Cave Run Lake, Daniel Boone National Forest |
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Installation
The work was sponsored by the Department of Defense, Advanced Research Projects Agency (ARPA) for the Technology Reinvestment Project to demonstrate the application of high volume/low cost production of high performance composite material structures in the infrastructure sector.
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Under the direction of Dr. Issam Harik, researchers at the University of Kentucky achieved the complete design, fabrication, and testing of the bridge and its components. The analysis, design, and construction techniques of the composite components were undertaken by the Great Lakes Composites Consortium, Wisconsin, and Basic Industry Research Laboratory (BIRL) at Northwestern University, Illinois.
This information has been sourced, reviewed and adapted from materials provided by Strongwell Corporation.
For more information on this source, please visit Strongwell Corporation.