Flexural and Shear Behavior of Reinforced Concrete Members Strengthened with a Discrete Fiber-Reinforced Polyurea System

Abstract

Recent research has been conducted to evaluate the benefits provided by externally-applied discrete fiber-reinforced polyurea (DFRP) coating systems. This coating was proposed to allow for ease of construction in repair-retrofit situations and to provide multihazard benefits, ranging from blast or impact fragmentation mitigation to seismic reinforcement and general strengthening. This phase of research investigated the flexural and shear reinforcement capabilities of the systems. Testing parameters included type of structural failure, polyurea, and fiber volume fraction. Additionally, the effects of the thickness of the composite system were considered. Concrete beam specimens were fabricated and coated per the designed test matrix and subjected to four-point bending. Analysis was based on ultimate capacity, deflection, overall ductility, and the qualitative observations of coating adhesion and fragmentation confinement. In addition, a theoretical model was developed and validated to describe the flexural behavior of the polyurea-coated beams and to normalize the test data for comparison. Results presented in this paper suggest measurable strengthening for both flexural and shear capacity provided by the coating system and substantial gains in ductility.