FRP confined masonry under compression: database collection and design proposals

Fiber Reinforced Polymer (FRP) materials have now reached the status of well-established technical solution for the external confinement of existing concrete or masonry members. Within this context, the scientific literature collects a number of experimental investigations proving the capability of the FRP wrapping in improving the mechanical behavior of members. However, from an analytical point of view, while several formulations are available for evaluating the compressive strength of FRP confined concrete, no general accredited formulae can be found for masonry columns, also due to the higher complexity and heterogeneity of this material with respect to concrete. With the aim to provide an updated contribute on this topic, this paper presents an analytical study on the FRP confinement of masonry columns with the twofold objective to: a) propose new models for the estimate of the compressive strength, and, b) assess existing formulae. A wide database including results of compression tests on over 230 masonry members externally wrapped with FRP was assembled from the literature. The experimental results were employed to develop new relationships for the estimate of the compressive strength of the FRP confined masonry through best-fit analyses. Comparisons with some formulations available in the literature and international guidelines were performed.