In-Service Performance and Behavior Characterization of the Hybrid-Composite Bridge System

The Hybrid Composite Beam (HCB) system is an innovative structural technology that has been recently used in bridge construction within the U.S. transportation network. In this system, the superstructure consists of a conventional reinforced concrete deck supported by Hybrid Composite Beams. Each beam is comprised of a glass-fiber reinforced polymer (FRP) box shell containing a tied parabolic concrete arch. Inclined stirrups provide shear integrity and enforce composite action between the HCBs and the concrete deck. This investigation focuses on evaluating the in-service performance of a newly constructed HCB bridge superstructure located on Route 205 in Colonial Beach, Virginia. A live load test was conducted using tandem axle dump trucks under both quasi-static and dynamic conditions. Results obtained from the experimental investigation were used to determine three key behavior characteristics, which were validated by a finite element model. Dynamic amplification and lateral load distribution were found to be reasonable in comparison to the assumed design values. The testing program also included internal and external measurement systems to help characterize the load sharing behavior of the HCB on an element level. The main load carrying elements are the deck in compression and the steel ties in tension, and the FRP shell did not act compositely with the internal components due to local bending effects of the thin arch, and de-bonding of the steel and FRP interface. An evaluation of common non-destructive evaluation techniques was also performed and recommendations provided for the health monitoring and long term inspection of critical load carrying components of HCB systems.