Strengthening of Reinforced Concrete Arches with Externally Bonded Composite Materials: Testing and Analysis

Abstract

An experimental and analytical study that includes testing to failure of fiber-reinforced polymer (FRP) strengthened medium-scaled reinforced concrete shallow arches and the application of a specially tailored high-order finite element for their analysis is presented. Three arches are tested. One is used as a control arch, whereas the other two are strengthened with externally bonded FRP strips in different patterns. The loading system includes six nonsymmetric vertical point loads equally spaced along the arch. The theoretical study is based on a multilayered finite-element approach, which accounts for the deformability of the adhesive layer and its shear and radial normal (through the thickness) stiffness. The arch is modeled as a polygon that consists of inclined specially tailored high-order finite elements. The results show that applying the FRP strips leads to an increase of about 40% in the failure load of the arch, changes to the cracking pattern, and a significant increase in deflection capacity. Edge debonding of the FRP strip is observed during the test but without causing total failure of the arch. The ability of the theoretical model to describe the overall structural response, the stress transfer mechanism in the strengthened arch, and the interfacial stresses and the local stress concentrations near irregular points are also demonstrated. Together they throw light on the behavior of the FRP-strengthened arch and on the evolution of its failure mechanism.