Elena Mele

• PhD
• Professor (Full) at University of Naples Federico II

The multi-staged XENON program at INFN Laboratori Nazionali del Gran Sasso aims to detect dark matter with two-phase liquid xenon time projection chambers of increasing size and sensitivity. The XENONnT experiment is the latest detector in the program, planned to be an upgrade of its predecessor XENON1T. It features an active target of 5.9 tonnes o...

The paper focuses on tall timber buildings. The major aim of this paper is to identify the most sustainable and efficient structural system to increase the height of timber buildings, also considering steel–timber hybrid structures. First of all, a brief review of tall buildings’ evolution is presented to understand why tall timber buildings are co...

Vertical extensions of existing buildings can be realized through Intermediate Isolation System (IIS): the extension, equipped with a base isolation system on the rooftop of the existing building, can work as a mass damper, thus reducing the seismic demand on the old structure. The idea proposed in this paper is to predict the elastic or inelastic...

Gridshell structures require an intricate design activity that shall comply with several design goals of diversenature. This design phase can be approached with different methods and strategies and usually requires multiple competencies from different scientific fields. In this context, a common benchmark, called FreeGrid, is proposed to the scient...

FreeGrid is meant to offer a common benchmark to test and compare different approaches to the design and optimization of steel gridshells, from man-based heuristic design to AI-based one. FreeGrid sets three design baseline problems: a barrel vault, a paraboloidal dome, and a hyperbolic paraboloid, having their spring line partially not constrained...

This paper reports a study on the Intermediate Isolation System (IIS) applied to existing buildings. This kind of application is particularly suitable when a vertical addition is planned for buildings in seismic zones; in such a case, an isolation system can be placed at the base of the extension to prevent the increase, or, better, to reduce the s...

In this paper, the strategy of Intermediate Isolation System (IIS) is proposed for the vertical extension of an aggregate of masonry buildings located in Pozzuoli, south Italy. The effectiveness of IIS working as a nonconventional Tuned Mass Damper (TMD) for the existing construction is assessed in terms of reduction of seismic demand and damage in...

Tuned Mass Dampers (TMD) have been widely used in the passive vibration control of engineering structures, both under wind and seismic loads. Under wind loads, a proper frequency tuning ensures a significant response reduction of the primary structure. While under wind loads the structure is likely to remain in the elastic range of behaviour, when...

In the present paper, additions in structural steelwork are utilized for giving new life to old buildings in regions characterized by medium/high seismic hazard. Two models are here proposed, i.e.: vertical addition for masonry buildings and lateral addition for r.c. buildings. For the model of vertical addition, the connection between the masonry...

A great attention has been recently paid to sustainability and efficiency in the field of civil engineering. In this context, structural optimization processes combined with shape grammar constitute an important tool to support the design phase of large scale structures. This paper proposes shape grammars for the topology optimization of grid shell...

Tuned Mass Dampers (TMD) have been widely used in the passive vibration control of engineering structures, both under wind and seismic loads. Under wind loads, a proper frequency tuning ensures a significant response reduction of the primary structure. While under wind loads the structure is likely to remain in the elastic range of behaviour, when...

In the present paper, additions in structural steelwork are utilised for extending the life of old buildings in regions characterized by medium/high seismic hazard. Two models are here proposed , i.e.: vertical addition for masonry buildings and lateral addition for r.c. buildings. For the model of vertical addition, the connection between the maso...

In the present paper, additions in structural steelwork are utilized for giving new life to old buildings in regions characterized by medium/high seismic hazard. Two models are here proposed, i.e.: vertical addition for masonry buildings and lateral addition for r.c. buildings. For the model of vertical addition, the connection between the masonry...

In recent years, the need of improving safety standards for both existing and new buildings against earthquake and wind loads has created a growing interest in the use of the so-called tuned mass dampers, exploited to control, in active or passive way, the dynamic response of structures. To design and optimize tuned mass damper systems, the effecti...

A great attention has been recently paid to sustainability and efficiency in the field of civil engineering. In this context, structural optimization processes combined with generative design constitute an important tool to support the design phase and to guarantee the exploration of a wide space of solutions. A generative approach recently re-eval...

Background Diagrid structures, widely used for the tall buildings of the third millennium, are characterized by a very effective behaviour in the elastic field due to the grid triangulation. In particular, under horizontal actions, axial forces and deformations mainly arise in the structural members of the diagrid, thus resulting in the reduction o...

Mass damping is a well known principle for the reduction of structural vibrations and applied in tall building design in a variety of configurations. With mass usually small (around 1% of building mass), the properly “tuned” mass damper (TMD) shows great effectiveness in reduc-ing wind vibrations, but minor advantages under earthquake excitations....

A stiffness-based method for the preliminary design of outrigger braced skyscrapers is proposed. The method is founded on the concept of uniform distribution of deformation. This approach originates from the minimum-compliance optimization, in which the stiffest layout for the structure is sought for a given amount of material. Design variables inc...

Urban densification represents one of the biggest universal challenges of contemporary cities: the increase of urban population requires new spaces to accommodate the growing demand for housing, working and tertiary activities. However, the land available for new constructions in highly urbanized areas is very limited. In this framework, the vertic...

An innovative generative design strategy, based on shape grammar, is proposed for the minimum‐weight design of diagrid tall buildings. By considering the building as a three‐dimensional vertical cantilever beam with a tubular section under horizontal load, it is evident that bending and shear stiffness demands vary along the width and elevation of...

In this paper, an innovative diagrid-like pattern for tall building structures is proposed. Based on the concept of principal stress trajectories, the pattern is characterized by triangular units with angle varying along width and elevation, and, being the expression of forces flow arising in the building façades, it is expected to be highly effici...

Inter-story isolation system (IIS, also appointed as mid-story isolation), is currently spreading and gaining significant popularity, mainly in Japan. However, while more than sixty applications have been realized in nearly twenty years, the conceptual framework for dealing with the design problem of IIS is not well established, since the IIS combi...

This paper investigates the potentials of inter-story isolation systems (IIS) for retrofitting irregular masonry buildings by means of an isolated vertical addition realised on the roof of the existing structure. By assuming a case study, a wide parametric analysis is firstly carried out on lumped-masses model for identifying the dynamic properties...

A stiffness-based procedure for the preliminary design of outrigger braced structures is proposed and applied to a case study 43-storey building. The procedure is based on the concept of uniform deformation design, and originates from the minimum-compliance optimization approach. The core flexural stiffness, the outrigger-belt elevation, and the cr...

The Inter-story Isolation System (IIS) is a passive strategy in the field of structural vibration control deriving from the Base Isolation System (BIS). The IIS is realized shifting the position of the isolation layer upward, from the base of the building to an intermediate level, thus sub-dividing the structure in two portions, namely the lower st...

Intermediate isolation system (IIS) is currently spreading and gaining significant popularity, mainly in Japan. However, its potentials are not so well-known in European countries, and in USA only one application to building retrofit is registered. The dynamic behaviour of intermediate isolation systems, more complex than the two-degree-of-freedom...

In this paper, a first insight into the role that non-conventional structural patterns might play in the design of tall buildings is presented. The idea is to explore the mechanical properties of selected non-conventional structural patterns, in the form of both regular (Hexagrid) and irregular (Voronoi tessellation inspired) arrays, in order to as...

Structural configurations best addressing the traditional requirements of strength and stiffness for tall buildings are the ones employing the tube concept, whose efficiency, however, is strictly related to the involved shear-resisting mechanism. In this perspective, diagrid structures – the latest mutation of tube structures – show an extraordinar...

Sandwich foam beams and panels, made of solid skins and aluminium foam core, are widely applied in high‐tech engineering fields; on the contrary structural use in the civil engineering field is not so common. An initial, explorative study on the structural application of metal foams in the civil and building engineering field is presented in this p...

The paper validates Ω* method proposed by some of the authors in previous papers for design of X-Concentric Braced Frames (X-CBFs). This method was obtained relaxing some of the requirements of the method provided by the European seismic code (Eurocode 8, EC8). Therefore, Ω* method is conceptually similar to that of EC8, which makes it easy to be i...

Arches are among the most widely used and characterizing elements in masonry structures, particularly in historical buildings and churches. They are susceptible to severe damage due to seismic actions, excessive vertical loads, or support settlements. While an exhaustive literature is available for the behaviour of arched structures under vertical...

In this paper, a first insight on “non-conventional” structural patterns, to be adopted in tube configurations for tall buildings, is provided. The idea is to investigate the mechanical properties of non conventional structural patterns, both regular (Hexagonal Grid, i.e. HexaGrid) and irregular (grid inspired by the Voronoi tessellation), in order...

Sandwich foam beams, made of solid skins and aluminium foam core, are usually applied in high-tech engineering field while they are not yet adopted in civil structures. An initial, explorative study on the structural application of metal foam is presented in this paper. The potentials of sandwich foam beams are studied through analytical models and...

Stability of isolation rubber bearings is a topic widely studied and concerns (1) the critical load capacity in the undeformed configuration, under long-term load (gravity) effects; and (2) the stability condition under short-term vertical pressure (due to gravity plus seismic loads) at large lateral deformations. In this paper the problem of elast...

This paper provides a first insight on tube configurations based on non conventional structural patterns for tall buildings. The idea is to investigate the mechanical properties of non conventional structural pattern both regular (Hexagrid) and irregular (inspired by the Voronoi tessellation) to assess their applicability in tall buildings, and to...

The paper analyses the seismic performance of steel structures with X Concentric Braced Frames (X-CBF) designed both according to Eurocode 8 and according to a new design approach proposed by the authors in previous works. In detail, for validating the proposed design methodology, non-linear dynamic analyses have been carried out by using the compu...

This paper provides a first insight on tube configurations based on the hexagonal shape (hexagrid) for tall buildings. The idea is to investigate the mechanical properties of hexagrid to assess their applicability in tall buildings and to compare their potential efficiency to the more popular diagrid systems. For the above purposes, a general homog...

The efficiency of a long-span structure relies on how material is locally distributed within a fixed structural shape. In this paper a design procedure for thin plates made of three layers of a depleted material subject to a distributed vertical load is proposed. The investigation is driven by the idea of the optimal material organization and has t...

SUMMARY The procedures and formulations suggested in literature for the design of diagrid structures start from the assumption that diagonal sizing process is governed by the stiffness requirements, as usually occurs for other, less efficient, structural types, and that member strength demand is automatically satisfied by the cross section resultin...

In this paper the authors define a framework for assessing the “local” structural issues in the design of diagrid tall buildings, and present a methodology for establishing the need for a specific secondary bracing system (SBS) as a function of the diagrid geometry. Further, design criteria for secondary bracing systems are worked out and applied t...

The originality of form is one of the new trends that can be identified in the current design of tall buildings. In this design trend, the so‐called diagrid structures, which represent the latest mutation of tubular structures, play a major role due to their inherent esthetic quality, structural efficiency and geometrical versatility. In this paper...

This paper concerns the seismic response of Palazzo Centi after the 2009 L'Aquila earthquake. Built in the second half of XVIII century, Palazzo Centi is a three-storied building characterized by a rectangular plan with a central court. The vertical structural system is made of masonry walls arranged in plan to form a regular mesh. After the 2009 L...

The seismic behaviour of masonry churches damaged during the 2009 L'Aquila earthquake is studied in this paper. Four important basilicas are considered in order to derive general conclusions from the damage assessment and the performance analysis. As a general result of the comparison between the post-earthquake survey activity and the structural a...

In this paper some modifications to the design procedure, currently implemented in the modern European seismic code for ductile cross concentric braced frames (X-CBFs), are proposed. The code procedure is aimed to obtain a ductile and dissipative ultimate behaviour by imposing that the yielding of diagonal members occurs before the damage and prema...

The paper deals with the problem of evaluation of the panel zone (PZ) shear strength in beam-to-column connection. To this aim, the mechanical behaviour of the PZ and the European and American code provisions for the design of PZ are examined and critically discussed. Non-linear FEM analyses and experimental tests carried out on beam-to-column stee...

In this paper, the problem of shear buckling in the panel zone of beam-to-column connections is examined. In particular, following the application of the shear buckling theory for rectangular plates, both in the elastic and in the plastic field, and a critical review of American and European provisions for panel zones, a parametric FEM analysis usi...

In this paper the seismic response of four church buildings in the l’Aquila April 2009 earthquake is analyzed. The buildings are: St. Giusta church, St. Maria di Collemaggio Basilica, St. Silvestro church and St. Pietro di Coppito church. The analyses are carried out by employing a “two-step” procedure suggested by the authors and already applied t...

The severe damage to masonry buildings after earthquakes has pointed out the need of studying new seismic protection techniques in order to guarantee appropriate safety levels against earthquakes. In historical buildings, such as basilica churches, a seismic rehabilitation should have also a minimum impact on the construction, preserving the origin...

In this paper, a simple formula for predicting the horizontal capacity of masonry portals is proposed and discussed. Moving from the approach firstly introduced by J. Heyman in his keystone paper The Stone Skeleton [Heyman J. The stone skeleton. International Journal of Solids and Structures 1966;2:249–79], the principle of virtual works for olonom...

The paper investigates the behavior of beam-to-column panel zone (PZ) under monotonic load. A numerical FE model which accounts for both mechanical and geometrical nonlinearity is introduced and briefly discussed. To validate the FE model, a preliminary comparison with experimental tests is established. In order to quantify the imposed demand and t...

In this paper the non-linear responses of three and six storeys concentric braced frames (CBFs) designed according to different seismic codes are illustrated. Particularly, with the purpose of studying the influence of the structural model and of the material behaviour on the non-linear response of braces, different geometrical models and material...

Concentric braced frame (CBF) typology is widely used in steel structures to increase lateral stiffness and consequently reduce drifts under wind and earthquake loads. During a strong motion, bracing members are subjected cyclically to large inelastic deformations in tension beyond yield and compression in the post-buckling range. This kind of beha...

In this paper, a simplified procedure for assessing the seismic capacity of masonry arches is proposed. The algorithm couples two quite simple analysis approaches, i.e. FEM linear analysis and limit analysis applied following Heyman’s hypotheses to a pre-chosen failure mechanism. In particular, linear analysis is used for detecting tensile and comp...

The seismic performance of partial perimeter and spatial moment resisting frames (MRF) for low-to-medium rise buildings was investigated. Extensive design analyses of the perimeter frame buildings and consistent design of spatial frame systems, as an alternative to the perimeter configuration, were conducted within the analytical study. The seismic...

In this paper the results of a test program devoted to the assessment of the cyclic behavior of beam-to-column welded connections are presented. The specimens are representative of the common European practice, which differs from both U.S. and Japan practice, due to the size of the connected members and to the welding technique and details. Three s...

In this paper a basilica-type church is analysed in order to assess its structural behaviour and seismic vulnerability. For this purpose, an effective two-step procedure has been used, consisting of: (a) 3D static and dynamic linear analyses of the structural complex, and (b) 2D nonlinear push-over analysis of the single macro-elements. The results...

In this paper, the applicability of different numerical techniques for the analysis of masonry structures is investigated, comparing the computed results with the experimental test data obtained on a full-scale masonry specimen. Three approaches are taken into account. Namely, the standard FEM modelling strategy, based on the concepts of homogeniza...

Welded connections, widely used in seismic moment resisting frames (MRFs) in USA, Japan and Europe, have been extensively investigated during the 1990s in order to improve their performance under severe earthquakes. In order to correctly evaluate the results of experimental research on welded connections, the differences among the American, Japanes...

Welded connections, widely used in seismic moment resisting frames (MRFs) in USA, Japan and Europe, have been extensively investigated during the 1990s in order to improve their performance under severe earthquakes. In order to correctly evaluate the results of experimental research on welded connections, the differences among the American, Japanes...

In this paper the results of an experimental program devoted to the assessment of the cyclic behaviour of full scale, European type, beam-column subassemblages with welded connections are presented. Six tests (five cyclic and one monotonic) have been carried out on three different series of specimens, encompassing a total of eighteen tests. The thr...

An experimental test program on a full-scale model representing a sub-assemblage of the cloister facade of the Sao Vicente de Fora monastery, retrofitted through base isolation, has been recently carried out at the European Laboratory for Structural Assessment of the Joint Research Centre of the European Commission. In this paper an overview of the...

An experimental test program on a full scale model representing a subassemblage of the cloister facade of the Sao Vincente de Fora monastery, retrofitted through BIS, has been recently carried out at the European Laboratory for Structural Assessment (ELSA) of the JRC. In this paper an overview on the laboratory model and on the experimental results...

The influence of random yield strength variation of steel members on the seismic behaviour of framed structures is faced in this paper. The most important parameters affecting the random inelastic response are pointed out and a parametric analysis is carried out in order to grasp the importance of the role played by each parameter. Moreover, the st...

In this paper the results obtained from the experimental tests on two alternative connection solutions (fully welded and top-and-seat with web angles) designed for the same beam-to-column joint are presented. The test program was planned with the aim of assessing the comparative behaviour of bolted and welded connections, and for defining the effec...

The seismic performance of three partial perimeter and spatial moment resisting frames is analysed in order to establish if the perimeter configuration has a detrimental effect on the seismic behaviour of buildings. For these frames, designed for three different seismic areas, a comparison is presented in terms of ultimate capacity and inelastic de...

A wide experimental program on different types (welded and bolted) of beam-to-column connections has been carried out at the Material and Structures Test Laboratory of the Instituto Superior Técnico of Lisbon The experimental tests have been performed on specimens representative of frame structure beam-to-column joints close to the ones typical of...