In-plane strength of masonry walls is affected by the resistant mechanisms activated in the walls, i.e., related to flexural or shear behavior. The latter one can occur in the walls according to different failure modes depending on both mortar and unit strengths and on the type of assembling, i.e., ‘regular’ or ‘irregular’ texture. In this paper, a critical review of the existing design formulations for the in-plane strength of masonry walls is firstly presented, with important information on the achievable failure modes depending on the geometrical and mechanical features of the masonry fabric. Then, experimental tests are collected from the literature and a comparison between theoretical and experimental results is carried out. The presented analyses are aimed to highlight the differences between the existing formulations and to identify the most suitable ones.

This paper presents the results of several numerical analyses aimed at investigating the in-plane resistance of masonry walls by means of two modelling approaches: a finite element model (FEM) and a discrete macro-element model (DMEM). Non-linear analyses are developed, in both cases, by changing the mechanical properties of masonry (compressive and tensile strengths, fracture energy in compression and tension, shear strength) and the value of the vertical compression stress applied on the walls. The reliability of both numerical models is firstly checked by means of comparisons with experimental tests available in the literature. The analyses show that the numerical results provided by the two modelling approaches are in good agreement, in terms of both failure loads and modes, while some differences are observed in their load-displacement curves, especially in the non-linear field. Finally, the numerical in-plane resistances are compared with the theoretical formulations provided by the Italian building code for both flexural and shear failure modes and an amendment for the shape factor ‘b’ introduced in the code formulation for squat walls is proposed.

The concept of vulnerability of the existing building stock is receiving increasing awareness and central importance in the scientific community working in earthquake risk mitigation. This assumes even more relevance when dealing with heritage structures located in relevant seismic hazard zones. This paper aims to identify and describe the earthquake-resistant features found in a unique masonry church in Ischia (Italy), and discuss their effectiveness on the impact of the post-seismic damage through the application of non-linear static analyses. The Santa Maria Maddalena Church represents one of the rare examples in which the technology of the Borbonic casa Baraccata (mixed timber−masonry construction), already well-known in the literature for its use in Italian seismic areas since the eighteenth century, is applied with the non-conventional combination of masonry and iron frames. The church was struck by the recent earthquake of 21 August 2017 with epicentre in Casamicciola Terme. The recorded post-seismic damage of the church evidenced non-relevant structural crack patterns, which are likely to be related to the efficacy of the construction system adopted.

Assessment of the mechanical properties of masonry materials is a key issue for evaluating the strength capacity of masonry walls. Two types of tests are usually adopted for experimentally evaluating the shear capacity of masonry walls: diagonal-compression and shear-compression tests. Different approaches are available in the literature for their interpretation. This paper reports an investigation into the behaviour of both unstrengthened and in-plane strengthened masonry walls with fibre-reinforced cementitious matrix materials under the two tests by means of a bi-dimensional non-linear-finite-element model. The model was first calibrated on the basis of comparisons with experimental results of diagonal-compression tests available in the literature. It was then used for comparing the numerical results obtained for the two tests in terms of local stress distributions for both unstrengthened and strengthened walls. The differences in the stress distributions in the tests, and the role of the reinforcement both on the distribution of stresses and on the global behaviour of the masonry walls, was highlighted.