Hybrid Bridge Structure Composed of Fibre Reinforced Polymers and Steel

Abstract

A 142 m long viaduct comprising a primary structure in steel with a lightweight fibre reinforced polymer (FRP) deck provided the solution for a demanding programme. The design stipulated a lightweight structure, combined with minimal disruption to the ongoing traffic underneath as well as low maintenance requirements. The resulting bridge consists of two continuous girders with the FRP deck in between the bottom chords integral to the bridge, with crossbeams only between the top chords. The steel and FRP parts were pre-fabricated, joined on-site adjacent to its final position, then moved into place in its entirety and the viaduct was inaugurated in early 2012.Pre-fabricated deck segments of 370 mm depth are integrally connected to the protruding flanges of the box-shaped bottom chords of the trusses. While the steel truss ensures transferring the vertical loads to the supports at both ends as well as at mid-span, the FRP deck transfers lateral horizontal loads to dowelled supports at mid-span and at the abutments. The deck is thus an integral part of the bridge and shows the structural versatility of FRP and hybrid structures.