Dynamic Analysis of the Bentley Creek Bridge with FRP Deck

Abstract

This study investigates vibration characteristics of a truss bridge that has been retrofitted with a fiber reinforced polymer (FRP) deck. The bridge is located on State Route 367 in Wellsburg, Chemung County, New York. It is a 140-ft-long (approximately 42.7-m-long) truss structure, originally built with a noncomposite concrete deck. The concrete deck was replaced with a much lighter fiber reinforced polymer deck to improve the bridge load capacity ratings. This study investigates the vibration characteristics of the bridge as a result of the deck replacement and impact of these changes on the structural behavior. The results indicate that the fundamental frequency for the current structure with the FRP deck is approximately 45% higher than that for the original structure with a concrete deck. The computed bridge fundamental frequency correlated well with field data. When compared to the concrete deck bridge, the FRP deck bridge resulted in lower dead load forces, higher live load forces, lower total forces, and higher live load stress ranges used in fatigue life estimates. Dynamic allowance was also determined for each of the selected members for both concrete and FRP decks. For the concrete deck bridge, the calculated dynamic allowance is higher than those used in bridge design specifications. Lower dynamic allowances were obtained for the FRP deck bridge.