Axial load behavior of circular and square concrete columns confined with sprayed fiber‐reinforced polymer composites

Many experimental and theoretical investigations have been carried out to study the compressive strength of concrete confined externally with unidirectional fiber‐reinforced polymer (FRP) composites. These unidirectional FRP(s) include carbon, glass, aramid, polyethylene terephthalate, and polyethylene naphthalates. In this article, the performance of randomly distributed sprayed fiber‐reinforced polymer (SFRP) composites on the enhancement of strength and deformability of concrete column through external confinement is investigated. The salient features of SFRP are quick and easy application as well as the uniform tensile properties in all directions. In the present study, 24 small concrete specimens were loaded to failure under the uniaxial compression loading. The study parameters covered SFRP thickness, fiber length, and column sectional shape (circular and square). Test results showed that the external confinement by SFRP is significantly effective to increase the strength and deformability of confined concrete. Based on the experimental results, the performance of existing strength models developed for the unidirectional FRP is assessed to examine its applicability to the SFRP confinement. It is found that none of the existing models is capable of accurately predicting the strength of concrete confined with SFRP. Finally, new strength models based on a linear relationship between confined concrete compressive strength and lateral confining pressure are proposed to predict the compressive strength of circular and square sections. The strengths predicted by the proposed models are found to have a good agreement with experimental results. POLYM. COMPOS., 37:2557–2567, 2016. © 2015 Society of Plastics Engineers