Composite Advantage Taps TYCOR® Technology for SuperFiberSPAN™ FRP Bridge Installation

Eight Mile Road Bridge, a short span concrete structure built in 1940, needed to be replaced in Hamilton County, near Cincinnati, Ohio. In addition to replacing the bridge deck slab, the abutments required rehabilitation to extend the life of the structure. County engineers had an aggressive goal for the aging bridge. Instead of a design that just provided a composite deck on reinforced concrete beams, engineers wanted a total bridge superstructure application. Their search led them to Composite Advantage (CA) and its integrated Fiber Reinforced Polymer (FRP) composite bridge system. CA designed SuperFiberSPAN™ using TYCOR^® fiber reinforced composite core material and then prefabricated the bridge superstructure with integrally molded beams and deck.

“Eight Mile Road was the first site in the United States to receive this integrated composite superstructure which was installed in April 2008 and opened for public use in June 2008.” said Steve Mary, engineer for Hamilton County. “Typically, failure or structural issues occur where materials are joined together. This system eliminates the connection joints between deck and beams. Our office has always had a special interest in using innovative materials and products because our objective is to continually improve our infrastructure and extend service life. This integrated composite bridge system was a logical next step.”

In developing SuperFiberSPAN, CA chose TYCOR over balsa and PVC foam for its strength and stiffness properties. “We had stringent deflection requirements to meet with this project,” said Scott Reeve, President of Composite Advantage. “PVC foam lacked the crushing strength and shear properties needed. Balsa was also an unsuitable core material choice because of its tendency to absorb water and the extra effort it requires when it is used for infusion molding.”

The composite superstructure also had to support high load concentration in a small footprint. “TYCOR possessed the structural properties to support the crushing loads and high shear loads from the tires of a fully loaded tractor trailer,” said Reeve. “Regular foam core products just can’t handle these types of requirements.”

Bridge parameters called for a 22 foot span and a width of 62 feet (1364 sf). Other specifications included the standard AASHTO HS 20 loading, an alternate military truck loading; L/800 deflection criteria; an integral concrete diaphragm; skew, cross-slope kick across the bridge to control asphalt thickness and an asphalt wearing surface.

CA used its unique infusion process to mold eight panels. Each panel spanned the bridge’s full length (22 feet) and was just under eight feet wide. TYCOR’s WIP infusion grooves allowed the resin to move quickly and efficiently throughout each panel. “TYCOR works very well with our resin infusion process,” said Reeve. “When we were first introduced to TYCOR by the WebCore technical staff, we saw the advantage of using a core material that can deliver the resin in a controlled manner. With TYCOR, we designed the manufacturing layout of some of our parts around this feature. TYCOR WIP infusion is the best way to ensure high quality infusion of the internal structure of sandwich panels.”

Once panel infusion was complete, a joint beam was bonded and bolted to join adjacent panels. Beams and deck were integrally molded together. The deck facings, beam shear webs and beam caps consisted of multi-axial fiberglass fabrics. The entire lay-up of beams and deck were infused with a corrosion resistant vinyl ester resin with pigment and UV inhibitor. Eight panels were molded to cover the width of the bridge. A structural test program was conducted to validate the design.

After the old bridge was removed, new abutments were poured. Bearing pads were located on the abutments at each FRP beam location. The panels were dropped in place starting with the east side of the bridge. All eight panels were installed in one day. “For this project in particular, the goal was to construct a total superstructure out of composites that could deliver a service life capable of exceeding 100 years,” said Mary. “In addition to a long life cycle, the non-corrosive nature of composites greatly reduces maintenance costs.

Because the integrated system prefabricates more of a bridge’s components into one piece, the cost premium for using high performance composite material is reduced. The overall cost of the integrated system is less than a conventional FRP bridge deck and separate beams because fabrication and assembly of the panels takes place under one roof to minimize production costs. The ability to receive TYCOR material on a just-in-time delivery basis was also an essential element. “In other instances we needed very quick turnaround to meet customer schedules,” Reeve explained, “and WebCore was able to provide the core material even faster then standard lead times.”

Hamilton County is also looking at applications for longer span bridges. Composite Advantage has integrated SuperFiberSPAN designs up to 50 feet. The integrated bridge system can be used for vehicle or pedestrian applications. Bridge performance has met expectations. CA uses TYCOR for all its FRP bridge products.