Gianfranco De Matteis

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...

NUMERICAL ANALYSIS OF SLENDER STEEL SHEAR PANELS FOR ASSESSING DESIGN FORMULAS

In the framework of passive control devices for the seismic protection of new and existing buildings, large attention is getting more focused on Steel Plate Shear Walls (SPSW). Such a system, which is characterized by the use of slender steel panels, has been largely adopted in the last few years both in the North America and Japan. The structural behavior of slender shear walls is strongly conditioned by buckling phenomena, which may have a significant influence also on the ultimate strength of the system, despite the development of stable post-critical behavior due to tension field mechanism. In order to assess the influence of the geometry on the structural behavior of shear plates, in this paper, the theoretical behavior of steel panels in shear, based on existing simplified methodologies (PFI method and strip model theory) is analyzed and then compared to the results obtained by an extensive numerical study carried out by means of accurate finite element models. The comparison between theoretical and numerical results has been developed with reference to different values of the thickness and by varying the aspect ratio of the plate. In addition, the influence of intermediate stiffeners is investigated. On the whole, the obtained results provide useful information for the correct design of slender steel plates in shear to be used as stiffening and strengthening devices in new and existing framed structures.

The Fossanova Church: Seismic Vulnerability Assessment by Numeric and Physical Testing

This article focuses on the seismic behavior of the church of the Fossanova Abbey (Priverno, Italy), which represents a magnificent example of a pre-Gothic Cistercian style monument. Aiming at investigating the seismic vulnerability of such a structural typology, experimental and numeric analyses have been carried out within the large European FP6 project PROHITECH. First, detailed investigations were devoted to identify the main constructional parts and the mechanical features of the constituting materials. Then, both ambient vibration tests and numeric modal identification analyses by finite element method (FEM) were applied, allowing the detection of the main dynamic features of the church. Based on such results, a refined FEM model reproducing the dynamic behavior of the structural complex was developed. The numeric study, carried out with a limit analysis, allowed the identification of the most vulnerable parts of the church, providing also an estimation of its actual seismic vulnerability. Finally, a shaking-table test on a 1-to-5.5 reduced scale model has been carried out checking the dynamic response of the complex structure as well as the constancy of the previous numeric study.

Damage Probability Matrices for Three-Nave Masonry Churches in Abruzzi After the 2009 L’Aquila Earthquake

ABSTRACT This article provides the main outcomes obtained downstream from a survey concerning the damage to 64 three-nave masonry churches in Abruzzi resulting from the 2009 L’Aquila earthquake. First, they are classified according to the typological, structural, and architectural features. Next, the main failure mechanisms observed in the immediate aftermath of the 2009 earthquake are identified and analyzed, taking into account both the global structural response and the local mechanisms involving specific parts of the churches. Damage related to the local mechanisms is classified by means of scores based on both the severity and extension of the revealed cracks. The single scores are combined to define an index measuring the global damage of each church. Such indices are therefore associated with six damage levels, the frequencies of which are organized into damage probability matrices. These matrices can be used in order to quantitatively evaluate the damage scenarios that the studied population of buildings revealed after the seismic event, as well as to predict the damage level that could be expected on similar churches for future earthquakes.

Experimental and Numerical Researches on Aluminium Alloy Systems for Structural Applications in Civil Engineering Fields

Structural research and applications of aluminium structures in civil engineering field have grown extensively in the last decades. Low weight, corrosion resistance, production of special profiles by extrusion and aesthetic quality of the aluminium material, together with the availability of specific and detailed design codes at both Italian (CNR-DT 208/2011) and European (Eurocode 9) level, have furthered such a development.On the other hand, in recent years, several experimental and numerical researches have been developed in order to improve the comprehension of the structural behaviour of aluminium elements, such as extruded and welded members, connections and joints, special devices, giving an important contribution to the present structural codes.This paper gives an overview of some of the researches developed recently by the authors which are strictly connected to the design and innovation of aluminium alloy structures. In particular, the behaviour of aluminium alloy members, joints and seismic protection devices is analysed, illustrating the results obtained by the above research programs. They put into evidence interesting aspects that deserve further research activities for improving the present codes on aluminium structures, as well as the high potentiality of the aluminium material to be used as alternative to steel for interesting and convenient applications in structural engineering.

Influence of Column Axial Load and Heat Affected Zone on the Strength of Aluminium Column Web in Tension

The component method for aluminium joints has been recently introduced in some codes and guidelines. Nevertheless, it is still in need of some development and improvement, as in some cases it was obtained by adapting the existing formulations that are valid for steel. The current paper presents the main outcomes of a parametric analysis carried out by means of finite element (FE) numerical models for determining the influence of both column axial load and heat affected zone—in the case of welded details—on the structural response of the column web in a tension component. The proposed study integrates previous research carried out by the authors, where the influence of the assumed alloy was investigated and interpreted by corrective parameters expressed as a function of both the material strain hardening and ductility.

Structural Individuation of Damages Occurred on St. Gemma Church in Goriano Sicoli during the 2009 L’Aquila Earthquake

The current paper presents the first part of a study in progress devoted to analyse the St. Gemma church in Goriano Sicoli, which has been seriously damaged by the 2009 L’Aquila earthquake. Firstly, the main effects provoked by L’Aquila Earthquake on ancient historical centres, with particular regard to buildings belonging to the cultural heritage, are described. Then, the St. Gemma church is investigated in detail. The main geometry and structural details of the church are shown and damage occurred during to the seismic event of 6.04.09 is critically analysed and discussed. Finally, the main outcomes of dynamic tests carried out on the damaged church, in order to detect its main natural frequencies and mode shapes, are provided.

The effects of L’aquila earthquake on the St. Gemma church in Goriano Sicoli: part II—fem analysis

In order to integrate the study undertaken in the companion paper, the main outcomes of a linear response spectrum analysis carried out by the FEM numerical model of the St. Gemma church in Goriano Sicoli are presented in current paper. The proposed model has been calibrated on the basis of ambient vibration tests carried out on the building in the damaged state. Numerical model reliability has been proved by its capability to reproduce the crack pattern observed on the church as it was provoked by the occurred earthquake. The structural response of the church has been investigated by interpreting the stress distribution with the aim of understanding the zone where the major stress concentrations occur. The purpose of the study is to provide useful indications on the main structural vulnerability of this type of building in order to extend the main outcomes to similar churches belonging to the same regional area, in order to get appropriate fragility curves.

Seismic vulnerability assessment of historic centers: description of a predictive method and application to the case study of scanno (Abruzzi, Italy)

ABSTRACT In this article, a predictive model for the seismic vulnerability assessment of old Italian historic centers is presented through its direct application to a meaningful case study, the historic center of Scanno, in Abruzzi, Italy. The proposed method is calibrated on the basis of the observations carried out on similar historic centers hit by the 2009 L’Aquila earthquake and is applied in order to provide likely damage scenarios by means of fragility curves. The method is based on the evaluation of a limited number of structural and typological parameters that can be obtained by simple and rapid inspections on buildings. In addition, it is conceived in order to provide useful information on the most effective anti-seismic strategies to be implemented on urban scale for pursuing a global mitigation of the seismic risk and for the application of suitable risk reduction policies. The final aim of the article is to give an applicative vision of the method, by providing instructions on how to judge the features of the buildings that are influential on their seismic behavior, as well as by showing the potentiality of the method itself in providing likely damage scenarios, also with the support of GIS-based representations.

Design and Performance Testing of a Skylight in Qatar

The current paper deals with an overview on façade industry with the purpose to be useful for the engineers involved in the structural and architectural design of curtain walls.The research activity has been based on both the structural calculation and the experimental test on the Le Boulevard skylight in Doha (Qatar), measuring 36m by 18m in plan, located at a height of about 42 m and subjected to a wind load of 1.7 KPa. The skylight, composed of steel rectangular curved tubes, glass and aluminium sandwich panels, is designed for a basic wind speed of 25 m/s as per Qatar Construction Standards. Two types of steel frames have been designed, one to support both the glazing and aluminium sandwich panel, and another to transfer all the loads to the main structure. Subsequently, a performance testing on a specimen extracted from the skylight has been performed. The test was carried out by Aluminium Technology Auxilliary Ind. (ALUTEC) on a specimen having length and width of 6.625 m and 3.315 m, respectively. The assessment procedures have been carried out following the “ASTM E283”, “ASTM E331” and “ASTM E330” standards. The results of the test have been found within the acceptable limits for the skylight components specified by the standards and required by the project specification.