A simplified approach to evaluate retrofit effects on curved masonry structures

Masonry vaulted structures are diffused all over the world, in many cases in historical and monumental buildings, often characterized by high seismic risk. For this reason their conservation should be investigated. Composite materials are usually used to retrofit different types of masonry and concrete buildings. The behaviour of masonry arches retrofitted at their intrados and/or extrados surfaces by means of externally bonded composite materials (FRP or FRCM) has been investigated. The load capacity estimate due to composite strengthening could be performed through finite element analyses. The numerical simulations provide important information about the mechanical behaviour of the masonry structures and on the composite-masonry interaction. However, such numerical analyses present often some drawbacks. For this reason it is useful to have simplified calculation methods to estimate capacity increase of masonry vaulted structures due to composite retrofit. Such simplified methods are the goal of this work and they consider linear and nonlinear behaviour of masonry. Validation of the proposed method is carried out by comparing predictions of the load capacity and failure mode with those obtained from shaking table experimental tests.