Modelling and analysis of FRP-strengthened masonry panels

The aim of this paper is the development of suitable mechanical models able to reproduce and, hence, to predict the response of masonry structures. In particular, the study is addressed to the modelling of strengthened masonry structures in which the introduction of new types of reinforcement, particularly the FRP (fibre-reinforced plastic) materials, strongly affects the structural response through complex interaction mechanisms between masonry and strengthening elements. In this paper two different approaches able to model the behaviour of un-reinforced and reinforced masonry structures are proposed. The first one is based on a micro-mechanical and multiscale analysis combined with the use of the kinematic and static theorems of the limit analysis; in this case a rigid-perfectly plastic constitutive relationship is considered for the masonry material and for the FRP–masonry interaction. The second approach is based on the use of macroscopic models. In this case, the constitutive relationship for the masonry material accounts for the softening effect throughout the use of a smeared crack approach. Moreover, different modelling strategies and constitutive laws are adopted for the FRP-reinforcement addressing particular regard to the delamination phenomenon. Numerical computations are developed for un-strengthened and FRP-strengthened masonry panels. The obtained results, in terms of the global response of the examined panels, are compared with the data available from experimental tests and interesting aspects are remarked.