Bending behavior of concrete-filled tubular FRP arches for bridge structures

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) are seeing increasing use in various infrastructure applications. This paper investigates the bending response of CFFTs for buried arch bridge structures. The thin-walled hybrid composite tubes developed at the University of Maine are fabricated from a combination of E-glass and carbon fiber braid infused with vinyl ester resin. The composite tubes function as confinement, tension and shear reinforcing, eliminating the need for conventional steel rebar. Additionally, the tubes serve as stay-in-place formwork, reducing construction time and complexity relative to conventional cast-in-place concrete structures. The objectives of this study are to experimentally assess the bending response of the concrete-filled FRP arches, compare test results with an analytical model, and illustrate the field application of this technology. To achieve these objectives, the bending load-deformation and moment-curvature response of CFFT's were investigated through quasi-static laboratory testing of three beams and four arches. The specimens were instrumented with displacement transducers and strain gauges at several locations. Two additional arches were subjected to 2,000,000 fatigue cycles and subsequently loaded to failure to assess the effect of fatigue on capacity. A nonlinear beam finite-element model that accounts for concrete confinement and cracking is presented. Model-predicted load-deformation and moment-curvature behavior as well as specimen capacity are shown to compare well with measured data from the arch testing, with arch capacity predicted within 4.2% of the average measured failure load. (C) 2012 Elsevier Ltd. All rights reserved.