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An atypical ‘baraccato’ system made of masonry walls encaged in iron frames was realized in the Ischia Island after the earthquake of 1883; an interesting example is represented by the Santa Maria Maddalena Church. Unfortunately, while several experimental and numerical studies can be found in the recent literature for traditional ‘baraccato’ systems (mixed timber and masonry elements), no information is available for iron-framed masonry structures. To fill this gap, the paper presents several parametric non-linear static analyses with reference to, firstly, simple iron-framed masonry panels and, successively, the façade of the Santa Maria Maddalena Church. All the numerical analyses were carried out by means of two modelling approaches with different levels of detail, i.e. finite element (FE) and discrete macro-element (DME) models. The numerical analyses allowed to: assess the reliability of the two models (FE and DME) into predicting similar results for the panels and the church façade with reference to both the unstrengthened and the iron-framed strengthened configurations; analyse the influence of the investigated parameters; evaluate the contribution of the iron frames on the overall behaviour of the strengthened masonry elements; and drive the choice of the most suitable modelling strategy for the whole church.

The paper deals with the description of detailed non-destructive in-situ tests and the analysis of the dynamic behaviour of the Santa Maria Maddalena church, located on the Ischia isle and partially damaged by the seismic event of August 21st, 2017. This church is a very special type of structure built in 1896 according to a mixed ‘baraccato’ constructive technique, based on tuff masonry walls strengthened by thin iron profiles in the main parts and timber elements in its back part. After the seismic event, a detailed survey of the church was done and passive thermography imaging as well as dynamic tests under operational conditions were carried out afterwards. The paper outlines a methodological approach where data and information collected from in-situ tests and surveys about geometry, masonry texture, crack patterns and vibration properties are collectively analyzed for the non-destructive structural assessment and finite element modelling of the church. The paper first describes how the experimental outcomes allowed to enhance the knowledge about the “baraccato” construction system specific to this church and its dynamic response under operational conditions. Setting of a three-dimensional finite element model of the whole church is described afterwards, considering the experimental results, to have a deeper insight into the dynamic behaviour of the structure under different assumptions, mainly regarding the constraint conditions at the roof levels and the values of Young’s modulus and unit weight of masonry. Specific analyses have been also carried out aimed at quantitative discrimination of the numerical vibration modes as ‘local’ or ‘global’. The obtained results remarked the importance of accurately planning dynamic tests on similar structures characterized by significant complexity in their structural organization to achieve a reliable assessment of their dynamic behaviour.

The ‘baraccato’ system is a typical building technique for masonry structures with clever earthquake resilient features, used for the reconstruction of historical city centers in Europe and especially in the South of Italy after some seismic events occurred in the 18th–19th centuries. An atypical and very innovative ‘baraccato’ system was realized in the Ischia Island at the end of the 19th century, when it was characterized by masonry walls encaged in iron frames other than timber elements. The paper presents the results of extensive numerical analyses on the behavior of such iron-framed masonry walls, with reference to both slender and squat geometrical configurations. The analyses are mainly focused on the assessment of: a) the more appropriate modeling strategies for simulating the connection between the iron frames and the masonry walls, b) the contribution of the iron frames on the overall nonlinear behavior of the masonry walls by means of push-over analyses. To achieve these goals, two models and corresponding software are used and compared for the numerical analyses, i.e. DIANA for the finite element model (FEM) and 3DMacro for the discrete macro-element model (DMEM).

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.

After the seismic event of August 21st, 2017 that hit the Ischia Island (Italy), in-situ surveys were carried out on several masonry churches located in the island in order to assess the damage induced by the earthquake. Among the inspected churches, a very interesting case study is represented by the Santa Maria Maddalena Church, located on the hill of Casamicciola Terme, close to the epicentre. The church was built in 1896 with a ‘mixed’ structure, made of yellow tuff masonry walls strengthened by iron profiles in its main body and by wooden elements in its back part. After the seismic event, in addition to a detailed survey of the church, thermography imaging and in-situ dynamic tests under operational conditions were carried out. The paper describes the experimental procedures adopted during the tests and the results in terms of experimentally identified fundamental modal parameters. An attempt of correlating the experimental results with those obtained from a finite element numerical model of the only church façade is carried out. The comparison evidences some discrepancies between the dynamic features of the single façade and the whole church. This confirms that the church is characterized by a ‘box behaviour’, most likely favoured by the presence of the iron frames, and, thus, the behaviour of the single façade cannot be considered independent of that of the whole church.

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.

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.