Confinement of masonry columns through SRG: experimental results and analytical prediction

Steel Reinforced Grout (SRG) composites represent, nowadays, a very compatible, reversible, and profitable strengthening solution for existing masonry buildings in earthquake prone regions. They can be employed to enhance the in-plane and out-of-plane behavior of masonry panels or to confine masonry columns. When these materials are applied to columns, different layouts can be adopted, mainly differing in the number of reinforcing layers. The objective of the present research is to evaluate the effectiveness of the use of SRG for the confinement of masonry columns. In more detail, clay brick masonry columns are realized and strengthened with 1 to 3 SRG layers. Uniaxial compression tests are then performed to evaluate the benefit provided by the composite material. Comparisons between the unreinforced and the strengthened samples are carried out in terms of load bearing capacity, deformability, and failure mode. In general, an increase in terms of strength and deformability was obtained by increasing the number of SRG layers applied. An analytical approach, derived by adapting the Spoelstra-Monti approach – formulated for FRP-strengthened concrete columns – to the case of SRG-strengthened masonry columns, is also adopted to predict the compressive behavior of the confined samples. The comparison between analytical and experimental results shows a good agreement, confirming the accuracy of the analytical prediction.