Ductility capacity assessment of masonry members strengthened with composites

Models able to assess the effects of composite strengthening on masonry structures are worthy of further developments. This is also evident in modern design codes and guidelines where, for the masonry, there is lack of well-established approaches. In fact, most of the strengthening applications on masonry structures are designed based on suggestions by the manufacturers, missing strict and clear calculations. Such an approach leads, very often, to the execution of large and therefore economically demanding strengthening systems, also not encouraging their diffusion. Furthermore, the use of excessive strengthening often involves an excessive, and above all involuntary, reduction of ductility capacity. It needs also further investigation the impact of peculiar behaviors of composites (e.g. up to trilinear stress strain behavior for FRCM) on the flexural response of masonry. In this paper the behavior of strengthened masonry members is analyzed accounting for the variability of mechanical characteristics of both masonry and the strengthening systems. The behavior of the members is analyzed in terms of the moment-curvature relationships. This approach allows to evaluate both the flexural capacity and the ductility capacity of the strengthened masonry sections. In fact, the ductility is a key aspect in the retrofit of masonry structures. Finally, the process of adimensionalization, allows to extend the results to any case, providing a useful tool not only for verification but also for the design of interventions.