Lightweight Solid Decks for Movable Bridges – Phase II.

摘要

Movable bridges often include open grid steel deck for its light weight and ease of installation. These decks, however, suffer from poor rideability and high maintenance costs. The primary objective of this research project was to search for a new generation of lightweight solid decks that address these issues. Alternative deck systems, including ultra-high performance concrete (UHPC)-high-strength steel (HSS) deck, and UHPC-fiber reinforced polymer (FRP) deck, and UHPC-FRP hybrid system, were developed and studied in this research. The UHPC-HSS and UHPC-FRP deck system showed a great potential to serve as viable alternatives. Accordingly, this phase of the project covered all studies needed for their design and implementation. Also, suitability of a UHPC-FRP hybrid bridge deck system as an alternative to open-grid steel decks was evaluated. The study confirmed that the proposed deck with only 4-inch overall depth and a self-weight of 20.88 psf for the deck with HSS reinforcement and 18.79 psf for the deck system with CFRP reinforcement meets the strength requirements for a 4-ft. stringer spacing. Additional work is required to ensure the deck with CFRP reinforcement meets the displacement criteria. The deck is not susceptible to punching shear of its thin slab, and fails in a ductile manner. Load distribution among the ribs, whether calculated based on deflections or strains, is consistent for both types of reinforcement. In order to study the long-term behavior of the proposed decks under the effects of a moving wheel load, additional testing was carried out at the Accelerated Pavement Testing (APT) facility of the Florida Department of Transportation in Gainesville, FL. A hybrid section of UHPC and FRP was considered as another alternative in this research. Based on test results, the main failure mode was at the interface with the top UHPC plate. The hybrid system requires additional improvement.