The paper focuses on trulli, which are ancient typical drystone constructions with inner hollow largely spread in the Puglia region in the southern part of Italy. The trullo is the cheapest structure that can be built in a calcareous territory using plain stones without using any mortar, and has assumed a number of different forms, initially used as protection for the farm equipment, and later evolving into a house. This paper presents the evolution over time of these structures, as well as their description and treatment from a structural point of view. The simplicity of both the materials and techniques for realizing these structures is currently the basis of many projects for the development and progress in emerging countries, and makes the study of their mechanics very topical.

The paper focuses on a number of original researches developed by the authors concerned with the development of new design approaches for smart base isolation systems for structures. Base Isolation (BI) systems represent the first kind of control devices applied to civil structures. In the paper, advancement in technology is exploited in this field, allowing to conceive new BI typologies possibly based on the adoption of special smart materials or on the coupling of the basic passive device with additional corrective devices, in such a way to minimize the disadvantages deriving from the simply passive system. Illustrated procedures also embed in the design pattern of base-isolation systems the interaction effects between structure and soil in order to provide the best tuning of the isolation parameters and to get the maximum performance of the devices, finally summarizing a number of original approaches to design under passive, semi-active and hybrid modes.

In the paper, the problem to find statistics of the response of structures with unilateral constraints when the structural pattern is affected by some uncertainty, is approached. In particular, the case of the elastic beam supported by an underlying rigid soil is investigated, under the assumption that the surface of the soil is not perfectly known, but is described by a suitable random process. It is shown that if the beam is discretized into a number of finite beam-elements, and only the ordinates of the soil profile under the nodal points are significant, the problem can be solved by the evaluation of a multidimensional integral. In most cases a Monte-Carlo procedure with "importance sampling" proves to be very efficient for numerical calculation of the above integral.

In the paper a theoretical procedure about the deformation process -up to the collapse condition-of a masonry 2D solid subjected to an increasing quasi-static loading condition is developed and the relevant model is presented. The presence of friction and of deformation sliding modes is introduced, which is the case when a masonry tissue made of regular blocks is encountered rather than a chaotic masonry, and the relevant optimization problem is formulated.

In the paper one summarizes a recent model for designing the reinforcement optimal distribution in the case of some planar elements, c.g. fiber-reinforced-polymers strips glued onto the surface of the masonry walls or internal tensile bars inserted in the concrete beams. The body material is considered continuous, homogeneous, isotropic, linearly elastic and resistant compression, so that a no-tension model where the tensile resistance is considered null is adopted. The reinforcement is considered to have an unlimited strength and is adopted exclusively where the fractures occur. In this way the procedure evaluates automatically the quantity of reinforcement that is necessary and the areas where it is needed. As regards to the adopted procedure one refers to the fundamentals of limit analysis combined with the topological optimization and some examples of solution are shown.

In the paper the performance of ancient masonry vaulted bridges is investigated through the analysis of a study case which is referred to, in the region Campania, that is the Devil‟s bridge on Sele river in Capaccio. The proposed methodological approach is aimed at emphasizing a number of features, including the main vault/fill interaction, the overall cooperation of the structural and non-structural components.

The paper focuses on curved non linear structures with lose material, mainly addressing the problem of safety assessment of masonry bridges under static loads. This issue has a fundamental priority when developing strategies at a territorial level, because of the central importance of these constructions on the territory, especially in European countries. Starting from the observation of the complexity of the bridge infrastructure, where many structural and non-structural components interact with each other for composing the overall response to external action, an approach is outlined for accounting for the fill action in the total or partial absorption of variable loads.

Modeling and analysis of masonry continuum through mechanical models that embed some low tensile skill of the masonry and account for its decay process during time is rarely treated in literature. More sophisticated models are to be considered able to produce results in major agreement with real data.The development of theoretical formulations aimed at a priori producing evaluations about the overall performance of these models have a central importance, since they allow to make reasoned computational choices about the mechanical models to be referred to for computations.In this paper one focuses on a special mechanical model for masonry bodies, which is referred to as Elastic Brittle tension (EB) model.Actually the EB model is evolutionary since the non-null tensile stress yield value is assumed to decay during time and converge towards the No-Tension behavior.This involves the need of investigating the relationships of the solution with other solutions related to more known mechanical models, which requires for the EB model the development of a proper theoretical formulation that is presented in the paper.One starts from the consideration that in this case, since the failure in tension is brittle, the theorems of Limit Analysis (LA) are not justified. Thereafter one sets up an approach to the problem aimed at investigating how far the collapse behavior of EB structures can be analyzed through the usual LA tools; some bounding thresholds for their ultimate load-carrying capacity with some original stability statements are then formalized.The proposed approach is here referred to masonry arches modeled under the EB hypothesis but it may be easily generalized to different structural typologies. (C) 2016 Civil-Comp Ltd and Elsevier Ltd. All rights reserved.

In this paper, we introduce a phenomenological model approximating the behaviour of masonry structures, which is based on a low-tension elastic–brittle (EB) assumption with evolutionary tensile behaviour. The EB model is conceived by embedding a decaying tensile strength in the material behaviour, and it is able to achieve good agreement with the real behaviour of masonry. Since the model is quite sophisticated, non-holonomic, and the EB solution depends—amongst other things—on the loading path, it is worthwhile to investigate the relationships with more manageable and stable models rather than searching for unreliable solutions that depend on poorly predictable data. Namely, whereas it is quite clear and largely agreed upon that structural models widely applied in engineering (like perfectly plastic or no-tension models or other ones) are well-conditioned problems, the same does not apply to brittle structures. In this case, exact solutions are hard to be found and are scarcely attractive from the engineering point of view since they also depend on the load history and on unverifiable variables such as the local tensile strength. In view of these considerations, in this paper it is proved that stress fields in tensioned EB problems can be approached by highly stable solutions, on the upper and lower sides of the relevant complementary energy, and that the approximation gets closer as the limit tensile strength of the brittle material becomes lower.

In the paper one addresses the problem of similar structures characterized by the same material and geometry, and subject to proportional loads. After introducing the relevant theoretical set up, some discussion about the response and the influence of dimensions of the structures, assumed to be made of masonry material, on their behaviour is figured out. The numerical investigation confirms the relations between variables inferred by the general formulation of the problem.

This paper presents a Particle Swarm Optimization-based topology optimization method for the design of negative permeability dielectric metamaterials.As the electromagnetic metamaterials have some physical properties not available in nature, they have attracted a huge scientific research interest for decades. In fact, electromagnetic metamaterials can exhibit simultaneously negative permeability and negative permittivity. The aim of this work is to find an optimal topology of a dielectric metamaterial that achieves negative permeability at a given frequency. A binary Particle Swarm Optimization is developed and applied to a negative permeability dielectric metamaterial topology design problem. The optimization process is achieved using a developed numerical model of the studied metamaterial, which is solved by the Finite Element Method.First, the governing equations and the weak formulation of the electromagnetic problem are presented. Then, the optimization problem to be solved is formulated. The developed binary Particle Swarm Optimization method, and the developed interfacing method are explained. Some numerical examples are presented to demonstrate that the binary Particle Swarm Optimization is adapted to the topology optimization of negative permeability dielectric metamaterials, at given frequencies, to demonstrate the utility and validity of the presented method.

The paper focuses on the problem of developing a reliable theoretical model for representing the bodies that exhibit a heterogeneous mechanical behaviour in tension and in compression. The proposed phenomenological model is characterized by an evolutionary tensile strength that is ruled by a decay law depending on the loading path. Such model is of particular interest, since it may be successfully employed, after suitable calibration of the tensile strength, for managing a class of materials that includes masonry bodies. In the paper, the fundamental postulates under multi-axial stress states are formulated and proved to hold at any stage of the loading path. The relationships of the solution of the introduced elastic–brittle model with solutions relevant to other more standard and well-behaved mechanical models are analytically investigated. Finally, two original theorems are enounced that allow to identify some upper and lower bounds on the solution, in energy terms.

In the paper the behavior of composite-reinforced masonry structures is discussed. One focuses on the problem of the reinforced structure under different modeling of the basic material keeping into account possible strength in tension of the masonry material. Actually the presence of the reinforcement requires the development of a specialized treatment, that is presented in the paper, with the purpose of exploring the dependence of the solution on more or less refined hypotheses about the masonry material in the presence of reinforcement. The original set up leads to the formulation of new bounding theorems for masonry structures reinforced by composites, with the masonry possibly modeled by an elastic brittle assumption.

The paper outlines an approach for improving the effectiveness and reliability of base isolation devices in civil engineering structures that undergo exceptional dynamic conditions.The strategy consists of designing the passive device in such a way to take into account the not-negligible soil-structure interaction effects. At this stage, the isolator is, then, designed in such a way to be optimally tuned on the basis of the characteristics of the structure and of the soil at the site. Anyway limits intrinsic in the effectiveness of the passive device cannot be completely overcome even when embedding in the design the influence of the soil filtering on the structural response. Therefore, at the second stage, an active vibration device is coupled to the basic isolator, which is, in turn, optimally designed for minimizing the structural response and control costs. The overall presented approach definitively produces an effective hybrid control base isolation, already optimized for the specific structure and soil in its passive component, and able to concentrate the active control effort only on the frequency ranges where it is required. (C) 2015 Elsevier Ltd. All rights reserved.

In the paper one focuses on masonry vaults and on the proper positioning of composite reinforcements for reducing the lateral thrust, on the basis of a theoretical formulation which is founded on a equilibrium approach devoted at selecting shapes of load patterns that can be equilibrated by relevant admissible solutions, also accounting for so called non-manageable loads. Areas to be strengthened are identified and the practically immediate and operative applicability of the procedure is shown through implementation in ad hoc set up calculus codes.

In this paper, an original variational formulation is set up for incremental solutions in masonry-like no-tension (NT) solids. After reformulating some incremental theorems originally introduced with reference to elastic–plastic continua, the analytical developments allow to identify some extremum properties of a suitably defined functional of the response variables (in terms of fracture strains) for NT solids, which are verified within each time step of the loading process. The final problem consists of a constrained optimization, where the objective functional is represented by a quadratic semi-positive definite function of the fracture multiplier and the constraints are imposed by the material admissibility conditions.

In the paper, one presents the theoretical set-up of an original formulation aimed at accounting for the contribution of the fill to the structural strength of masonry vaults and arches and at providing an evaluation about its skill of cooperating to stress absorption with the main vaulted resisting structure. Usually the action of components ordinarily regarded as non-structural members is often neglected in static analyses. Actually, it is a common practice to assume a number of elements of vaulted or arched constructions, such as the fill and the buttress, as completely unable to exert any structural action, rather than trying to evaluate their contribution; therefore, those are usually assumed to be a dead weight, unable to contribute to the bearing capacity of the vault. Starting from the consideration that the fill is somehow subject to some pre-compression because of the permanent load, an approach is proposed where the fill is considered to be able to provide a partial absorption of the variable loads with a reduced load transmission onto the main structural members. The procedure leads to more realistic evaluations about the safety assessment of vaulted structures, which are in major agreement with their real behaviour.

In the paper, the reinforcement of no-tension structures by the application of superposed high-strength sheets, or by the insertion of tensile bars, has been considered with the purpose to set up a design path aiming at the positioning of the new material according to some optimal criterion. In detail, no-tension models are adopted which are recognized as an effective tool for analyzing a wide class of structures (e.g., masonry and reinforced concrete members), and the equilibrium and the failure analysis of the reinforced body are developed with particular reference to its ultimate limit state of collapse. Finally, an approach through the “topologic optimization” is proposed for the identification of the optimal distribution of the reinforcement, and some of the obtained results are shown.