Beatrice Faggiano

Behaviour of aluminium alloy structures under fire

Abstract In the paper the attention is focused on the influence of high temperatures on the mechanical properties of the aluminium alloys selected by Eurocode 9 for structural uses. Therefore, based on the analysis of existing data taken from technical literature, the variation of the Youngs modulus, the conventional yielding strength, the ultimate strength, the hardening factor and the material ultimate strain are represented as a function of the temperature. A mechanical model, based on the well‐known Ramberg‐Osgood formulation, which appropriately takes into account the peculiarities of such materials at high temperatures, is provided. In particular, the combined influence of the hardening factor and temperature on the material stress‐strain relationship is considered and analysed. Then, the proposed model has been introduced in a finite element program, devoted to the global analysis of structures under fire. Finally, the results obtained for a simple portal frame structure, designed with different a...

Analysis of rectangular‐shaped collar connectors for composite timber‐steel‐concrete floors: Push‐out tests

Abstract The paper deals with the experimental analysis of an innovative connection system for composite timber‐steel‐concrete floors. The connection device consists of a collar composed by two or more parts, astride the timber beam, bolted together at adjacent wings. A rubber layer is interposed at the collar‐beam interface. The slipping action transmission is guaranteed by the superior wings of the collar or by a steel stud, purposely welded to the collar in the upper part, which are immersed in the concrete cast. In this paper push‐out monotonic tests on several rectangular‐shaped configurations of the connection system are presented, being part of a more comprehensive experimental campaign, aimed at the system performance evaluation and optimization. First, the preliminary numerical analyses, meant to define both the best geometrical characteristics of the specimens and the configuration of the testing apparatus, are illustrated. Then the push‐out tests, considering subsequent improvements of the conn...

Assessment of the Design Provisions for Steel Concentric X BracingFrames with Reference to Italian and European Codes

In the field of construction in seismic areas, the current Italian technical code for constructions NTC2008 is substantially based on the design criteria of Eurocode 8 (EC8), although with some differences. Focusing on steel structures with X Concentric Braces (CB), which is one of the most common seismic resistant structural typology in steel buildings, the paper illustrates a critical review of design methodologies specified in NTC2008, with the intent of providing simplified and more efficient design criteria and procedures able to ensure adequate safety levels under seismic actions, according to the modern design approach. The study is divided in two parts. The first part consists in the design according to the standard rules of typical steel X braced structures by linear analysis, both static and dynamic. The aim is identifying any possible weakness in the current design criteria, with particular reference to both the applicability of the proposed procedures and the actual possibility to size the bracing cross-sections and the connected structural members, like beams and columns. The second part consists in the assessment of the seismic response of structures examined. To this purpose, non-linear static analyses are performed in order to evaluate the most relevant behavioural issues, like the behaviour factor, the failure modes and the effectiveness of the capacity design criteria. Based on the results obtained, a proposal for the enhancement of design criteria is presented.

The Royal Palace of Naples: Diagnosis, Assessment and Structural Restoration of Complex Roofing Timber Structures

The paper presents an overview on the timber structures of the Royal Palace of Naples. Focusing on the roofs of the Historical Apartment, located at the second level of the palace, different structural typologies are illustrated. The structural identification was achieved starting from an extensive in situ survey, aimed at assessing materials, conservation state, geometries and static schemes. Therefore 3D FEM models of the study systems as whole were set up and the structural analyses carried out, allowing to catch the weaknesses in terms of strength and deformation capacities; the safety checks were performed according to Eurocode 5 provisions. Finally, on the basis of the acquired knowledge, the appropriate retrofitting techniques were suggested [1, . In particular, with reference to the Diplomatic Hall (II), details of the realized restoration interventions, based on mixed technologies, are presented [.

Complex Covering Timber Structures in Monumental Buildings: A Study Case

The paper deals with the study of the ancient timber structures of the Royal Palace of Naples. The attention is focused on the complex covering of the Guard Room (XXIX) of the Historical Apartment. Firstly, geometrical and mechanical in situ surveys are presented. Then, the capacity of the structure in terms of deformation and resistance is evaluated through numerical analyses on purposely set up 3D FEM models.

Bending Test on Composite Timber-Steel-Concrete Floor Equipped with Innovative Collar Connectors

In this paper a full scale monotonic static bending test on a composite timber-steel-concrete floor, equipped with innovative “collar” connectors, is illustrated. In particular, the specimen consists of two beams, made of ancient chestnut, connected to the concrete reinforced slab by means of purposely fitted upside wings of steel collars astride the beams themselves. The test is part of a comprehensive research activity, aiming at the evaluation and optimization of the collar connection device, developed within the European project PROHITECH (“Earthquake Protection of Historical Buildings by Reversible Mixed Technology”, 2004-2008).

ASSESSMENT OF THE DESIGN CRITERIA FOR CONCENTRIC V-BRACED STEEL STRUCTURES ACCORDING TO ITALIAN AND EUROPEAN CODES

The critical review of design methodologies provided by the NTC2008, in agreement with the European seismic code (Eurocode 8) for steel Concentrically Braced Frames with chevron (or inverted V) diagonals (CBF-V), carried out by deepening the seismic behaviour of such typical steel seismic resistant structures, aims to provide more efficient design criteria able to ensure adequate safety levels under seism. As reference case studies, common structural configurations of CBF-V are designed according to the NTC2008 provisions. Each case study is designed through both the Linear Static (LS) and Dynamic (LD) analysis. For braces either Circular Hollow Sections (CHS) or HE profiles are used. General critical issues have been evidenced in the design process. The seismic performance of investigated structures is evaluated by non-linear static analyses, in order to appraise the most relevant behavioural issues, like the behaviour factor, the failure modes and the effectiveness of the capacity design criteria. A discussion on the obtained results has allowed to point out the pros and cons of the current design approach.

Robustness of the Vesuvian roofs under the combined overload and high temperatures due to air falls

During an explosive eruption, a construction is hit by several actions, always associated to elevated temperatures, causing fires, possible explosions and reduction of the mechanical properties of the structural materials. In this paper the attention is focused on the analysis of a specific volcanic event, the so-called air fall deposits, generally falling from the eruptive column due to gravity. The study, starting within the European COST Action C26 project “Urban habitat construction under catastrophic events” (2006-2010), is concerned with the Vesuvius area at Naples in Italy. It faces two important aspects. The first items the proposal of a model for the air fall deposits action on the basis of a similitude with the snow load. The second item is the robustness evaluation against the air fall deposits of the most common roof types in the Vesuvian area, which are made of timber, steel and reinforced concrete. Therefore, some protection systems for mitigating the effects of the combination of overloadin...

Non-Destructive Tests and Bending Tests on Chestnut Structural Timber

In the context of a more wide research study for in situ mechanical identification of ancient timber structures by non-destructive techniques, the paper illustrates the experimental activity developed on structural elements made of old chestnut timber, 4x4x76 cm size: 24 squared specimens were extracted by six elements in actual dimensions, already used in a previous tests campaign. Non-destructive (ND: hygrometric, sclerometric and resistographic) and destructive (D: bending) tests were performed, the latter according to UNI EN 408 (2004) standard, in order to assess the mechanical properties and the collapse mechanisms of chestnut timber. Data gathered are presented in detail and, NDT-DT correlations, obtained through a linear regression approach, are provided to predict wood density, strength and modulus of elasticity of the tested members.

A Quick Level Methodology for the Volcanic Vulnerability Assessment of Buildings

Down the century, the volcanic eruptions have produced fatalities and economic losses. Today, almost half billion people and many conurbations (Tokyo, Mexico City, Yokohama, Seattle, Naples, etc.) are located in the proximity of very dangerous volcanoes. The volcanic risk mitigation of these areas requires a careful territorial planning together with an adequate knowledge of the behaviour of constructions under the eruption effects. The problem is very complex considering that a number of actions, such as ash fall, pyroclastic flows, flying fragments, volcanic earthquakes, lahars and tsunami, are produced by an eruptive event. Moreover, apart from the seismic case, the scientific literature relating to the structural volcanic vulnerability is poor. In this context, the paper illustrates a quick level methodology for the volcanic vulnerability assessment aimed at the identification of mitigation techniques. The ‘quick’ level, useful at territorial scale, is based on the identification of simple elements significant for the structures vulnerability. They are collected in a specific survey form, which adds to the information commonly required in case of the most familiar seismic vulnerability the ones specially related to all the volcano-induced phenomena. Then, the procedure furnishes a vulnerability index through the weighted combination of the vulnerability elements, according to the multi-criteria methods. The methodology proposed is a valuable tool that can be generally adopted in any kind of vulnerability investigation of buildings.