Performance of Confinement on Masonry

Most of the confinement models for masonry, empirical in nature, have been calibrated against their own sets of experimental data or they are simply derived from concrete. Masonry confinement is still highly correlated to concrete confinement, so that extensive experimental and theoretical studies are still needed to assess more reliable mechanical models of masonry confinement. Due to the extremely large variability in masonry performance, general equations cannot always be provided that are equally suitable for every masonry type. In this paper a novel approach is proposed, based on a mechanically based strength theory. In this way it is possible to differentiate various masonries based on the mechanical properties of the masonry as a whole. The proposed model is able to account also for non uniform confining stress fields, i.e. as it is found in non circular cross sections, so that the key innovative aspect is the different contribution of confining stress field not equal in the two transverse directions x and y. The effect of confinement is evaluated explicitly considering a plasticity model under triaxial compression. According to this model it is possible to assess the sensitivity of the confinement performance as a function of characteristic mechanical properties of masonry, and in particular those that potentially provide differences in the behaviour of different masonry materials.