A Procedure to Investigate the Collapse Behavior of Masonry Domes: Some Meaningful Cases

Masonry domes represent an important part of the architectural heritage. However, the literature about domes analysis seems less consistent than that referred to other masonry structures. The collapses that have happened in recent years as a consequence of seismic actions or lack of maintenance show the need for detailed studies. Here a limit analysis to evaluate the masonry domes behavior is presented. An algorithm based on the kinematic approach has been developed to evaluate the geometric position of the hinges that determine the minimum collapse load multiplier. The proposed procedure is validated by a comparison with some meaningful cases— the collapse of Anime Sante Church in L’Aquila, the collapse of San Nicolò Cathedral in Noto, the crack pattern of San Carlo Alle Quattro Fontane Church in Rome, and the analysis developed on Hagia Sofia in Istanbul. The comparison with real cases shows a good agreement between the model results and the phenomenological crack patterns

On the structural behaviour of existing RC bridges subjected to corrosion effects: Numerical insight

The evaluation of the structural behaviour of existing reinforced concrete (RC) bridges represents one of the most current structural engineering research topics due to their strategic importance, especially if they are subjected to corrosion effects which can lead to a significant reduction of load-bearing capacity of the main structural elements (e.g., the piers). In the last decades, different types of numerical approaches have been proposed for the evaluation of the structural behaviour of these strategic infrastructures, especially after the recent collapses that have affected this type of structures during last years. In this paper, the structural behaviour of an existing RC bridge subjected to corrosion effects due to carbonation is analysed by means of an efficient procedure based on the implementation of a Finite Element Model (FEM) where the main structural elements are implemented using only Timoshenko beam elements. The safety level of the bridge has been evaluated considering different load conditions (e.g. traffic load, seismic action, etc.) calculated according to the Italian Design Code (NTC2018). Finally, a retrofitting intervention is proposed in order to guarantee and adequate safety level of the bridge under the considered different load combinations

Thin corrugated-edge shells inspired by Nervi’s dome: Numerical insight about their mechanical behaviour

During the last decades, the constant evolution of the construction systems has led to the possibility of carrying out increasingly complex architectural project. Among the wide range of construction systems, thin concrete shells with corrugated-edge stand out for their relevance. In this paper, the mechanical behaviour of thin concrete corrugated-edge shell inspired by Nervi’s Flaminio dome has been analysed in detail, considering different load configurations (self-weight, uniform normal pressure and antisymmetric vertical load) and constraints (pure membrane vs. displacements restrained boundary conditions). Non-linear static analysis has been performed to assess the vertical load-bearing capacity of the corrugatededge shell considering a Concrete Damaged Plasticity (CDP) constitutive model and linear and non-linear buckling analyses have been carried out to evaluate the effects of the corrugation on buckling behaviour. The results obtained from linear and non-linear analyses have been compared with those obtained for a concrete thin smooth-edge shell having the same geometric global characteristics. The comparison highlighted improvements provided by corrugated-edge in terms of structural behaviour

Masonry arches simulations using cohesion parameter as code enrichment for limit analysis approach

A significant number of scientific research groups are still nowadays dealing with masonry material as the main focus of study since it provides an open field of research that is far from resolution in a standardized manner. As masonry structures are highly vulnerable to any level of natural hazards, especially seismic activity, both traditional and composite materials have been used as reinforcements in masonry and provide different solutions that meet the key requirements set out by cultural heritage organizations. Extensive effort has gone into developing appropriate techniques of assessment, that usually demand an individualized methodology of analysis which is to be handled through comparative studies requiring results validation. A suitable field of study is the Limit Analysis approach towards masonry structures, as it offers quite accurate and, more importantly, robust results regarding the necessity to resolve the issues involved in the masonry numerical representation so that reliable outcomes are drawn to enable the assessment of such structures. The enrichment of a Limit Analysis homemade code with the inclusion of cohesion and frictional behaviour at the interface level is able to account, in a simplified but very robust manner, the perplexing issues involved with the numerical assessment of reinforced masonry structures with particular reference to arches. The cohesion incorporation iscalibrated for a variety of in-plane applications, accounting for the joints’ indirect tensile strength, that is able to simulate the strengthening measures. Results obtained are validated with literature results and included in a comparative study between discrete numerical models that utilize different modelling strategies

On Dynamics of Elastic Networks with Rigid Junctions within Nonlinear Micropolar Elasticity

Within the nonlinear micropolar elasticity we discuss effective dynamic (kinetic) properties of elastic networks with rigid joints. The model of a hyperelastic micropolar continuum is based on two constitutive relations, i.e. static and kinetic ones. They introduce a strain energy density and a kinetic energy density, respectively. Here we consider three-dimensional elastic network made of three families of elastic fibers connected through massive rigid joints. So effective elastic properties are inherited from the geometry and material properties of fibers, whereas the kinetic (inertia) properties are determined by the both fibers and joints. Formulae for microinertia tensors are given

Discrete model for out-of-plane loaded random masonry

In this contribution, a simple and effective discrete element model based on rigid blocks and elastic interfaces with fixed contact topology, originally introduced for modeling regular masonry panels, is extended to the case of random masonry by introducing a perturbation parameter able to vary the width of each block. The proposed model is then able to better reproduce the microstructural behavior of historical masonry, that is characterized by dry or weak mortar joints between strong blocks, and, in particular, that is characterized by blocks often arranged irregularly. The hypothesis of rigid blocks, together with fixed contact topology between blocks due to the small displacements assumption, allows adopting an efficient solution method based on the determination of the stiffness matrix of the masonry assemblage. In this case, the stiffness matrix is able to account for the irregular block arrangement and, similarly to the case of regular masonry, the stiffness matrix is based on local joint stiffness, given that the contact actions along the joints are function of the relative displacements between adjacent blocks and the corresponding interface stiffness. Several numerical tests varying the random perturbation parameter are performed in order to evaluate the influence of randomness on masonry specimen behavior with respect to the regular case. Particular attention is given to the dynamic field by performing out-of-plane modal analysis of masonry panels. Furthermore, a homogenization procedure is applied to the random masonry and a numerical evaluation of the scatter between the discrete models and a 2D Reissner-Mindlin plate model is performed for varying perturbation parameter and for increasing heterogeneity parameter. As expected, when the number of heterogeneities in the structure is large enough, the average response of the random discrete model converges to an asymptotic response