Along with increased market demands on nutritionally fortified foods, edible coatings and films containing high concentration of nutraceuticals would provide alternative ways to fortify foods that otherwise cannot be accomplished with common processing approaches. Moving from this background, the aim of the present research is to design and evaluate nanostructures containing vitamins capable to be incorporated inside food approved packaging materials for a better food storage. In fact, such modified plastics could be useful to prolong food shelf life. Vitamin C and E were selected to be nanoincorporated in chitosan nanoparticles and the resulting NPs were characterized in vitro concerning the main physicochemical properties. The film packaging improved with the nanostructures has been mechanical tested to traction in order to determine the value of the maximum tensile stress when the detachment of the nanostructures appears. Adherence tests of the film in contact with different elements (simulating the food) have been performed to better characterize the improved packaging and the limit stresses acceptable before it loses the increased storage capacities. The aim is to keep the quality and characteristics of the packed food unchanged for a period longer than usual without affecting the freshness and taste of the food.

This article aims to analyze the mechanical characteristics of an innovative constructive system for arches and vaults made of hollow wooden boxes designed with interlocking joints. This new technology ensures at the same time good mechanical performances and faster installation and servicing. Experimental studies have been conducted on the base material, on the individual blocks and, thereafter, on an arch built in scale 1:1 to evaluate the displacements, the deformations and the maximum load to failure and to examine its compatibility with the provisions of the code on force. Finally a limit analysis has been developed to model the behavior of the structural system under the testing load.

This paper aims to analyze the mechanical characteristics of an innovative construction system for the realization of arches and vaults made of wooden hollow blocks with interlocking joints. They have been made by the partners Ltd Intini in the Regional Strategic Project Apulia " Innovative Structures and Testing of Advanced Materials "- S.I.S.M.A. This new technology is designed to encourage the use of wood, while ensuring excellent mechanical performance and facilitating a quick and easy assembly plant. Experimental studies have been conducted on the base material, the individual blocks, and then on a round arch built in 1:1 scale for evaluating displacements, strains, and the maximum load to failure to consider its compatibility with the code prescriptions.

This article aims to analyze the mechanical characteristics of an innovative constructive system for arches and vaults made of hollow wooden boxes designed with interlocking joints. This new technology ensures at the same time good mechanical performances and fast installation and servicing. Experimental studies have been conducted on the base material, on the individual blocks and, thereafter, on an arch built in scale 1:1 to evaluate the displacements, the deformations and the maximum load to failure and to examine its compatibility with the provisions of the code on force. Finally a limit analysis has been developed to model the behavior of the structural system under the testing load.

The results of an ambient-vibration based investigation conducted on a historical tower in Italy, to update the 3-D finite element model of the building are presented in this work. The main difficulties are related to the extreme in-homogeneity of the building and the presence of an elevator vain that occupies the posterior part of the tower, forcing to locate the accelerometers only on one fac-ade of the building. The assessment procedure include full-scale ambient vibration testing, modal identification from ambient vibration responses using three different identification methods, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. A very good match between theoretical and experimental modal parameters was reached and the model updating has been performed to identify some structural parameters.

In the present study, a new dissipation device for seismic protection of structures is proposed. This device is designed to dissipate the energy entering a structure during an earthquake through the activation of hysteretic loops of an aluminum plate located in the middle of the device itself. To maximize the amount of dissipated energy, we performed the design of the device requiring that the aluminumplate is stressed in an almost uniformway. In particular, the device is designed to concentrate energy dissipation in the aluminum core, whereas the external steel plates are dimensioned to give an adequate stiffness to the device and to limit instability phenomena. Characterization tests have been performed on two typologies of device designed for different levels of the maximum shear force (20 and 40 kN, respectively). Moreover, to verify the behavior of the aluminum–steel device, we performed characterization tests on the aforementioned devices realized without the aluminum plate. The results show that the steel plates behave elastically in the range of forces expected in the device during an earthquake, confirming that the aluminum plate is the main element for the hysteretic energy dissipation.

The aim of the paper is to present the dynamical identification of the bell tower of the Cathedral of Trani (Bari, Italy). The tower, built in 1200, is about 60 meters high and has a square plan with a side of about 7.50 meters; moreover it is connected to the church through a step supported by a pointed arch. The tower vibrations due to ambient actions have been recorded and analyzed with different modern algorithms in such a way as to estimate the modal parameters of the tower. The identified modal parameters were utilized to evaluate the dynamic interaction between the tower and the church and some mechanical properties of the structural elements.

The aim of the paper is to describe the non-destructive tests performed on the clock tower of the Castle of Trani (Bari, Italy). The tower, built in 1848, was realized in tufa masonry (Stone of Trani); it is about 9 meters high and has a square plan with a side of about 3.9 meters; it is built on the principal enter of the Castle and supported by a barrel vault reinforced with an arch. The non-destructive monitoring was performed by using specific accelerometers placed on the structure at different levels for measuring the acceleration in different points. The particular squat structure of the clock tower suggested the authors to make not only the traditional monitoring, with only environmental actions, but also forced tests by mean of a vibrodine adhoc designed and realized, for determining the building modal parameters. All the phases and the procedures of the experimental monitoring are described and the dynamic identification of the building modal parameters (the frequencies and their corresponding mode shapes) is presented discussing the results in both the operative conditions and the effects of the vibrodine excitation.

The aim of the paper is to present the structural analysis of an important historical building: the San James Theater actually used as the Municipality House in the city of Corfù. The building is made of carves stones and is located in the centre of Corfu, Greece. The study deals with the structural identification of such structure through the analysis of its ambient vibrations recorded by means of very accurate accelerometers. A full dynamic testing was developed using ambient vibrations to identify the main modal parameters and to make a non-destructive characterization of this building The results of these dynamic tests will be used for the model updating of a complex FE simulation of the structure. This analysis may present several problems and uncertainties for this stocky building. Due to the presence of wooden floors, the local modes can be highly excited and, as a consequence, the evaluation of the structural modal parameters presents some difficulties. The paper discusses the experimental tests and compares the results with those obtained from the analysis of a preliminary FE model obtained using a commercial software.

The scope of the paper is to present the analysis of an important historical building the “San James” theater actually used as the Municipality House in the city of Corfù (Greece). The building, that is located in the center of the city, is characterized by an extremely stocky shape, and by the presence of wooden floors. Moreover, the upper part of the building has been realized many years after the end of the works of the main part of the building. The aforementioned considerations do not allow to be sure about the “box” behavior of the building and makes the dynamic analysis and tests of great importance for the exactly comprehension of its structural behavior. With this aim an extensive experimental campaign has been performed: in detail 18 accelerometers with high sensitivity have been installed and the ambient vibrations of building have been recorded. In the present paper the performed experimental tests and the analysis of the experimental data are discussed and compared with a finite element model of the examined building. At this aim an important task of the present research is related to the consideration that all the floors are made by wood and so, the analysis of the experimental data and the dynamical identification could be influenced by the presence of local modes. This problem has been tackled by introducing a ‘single wall analysis’strategy for demonstrating the global behavior of the estimated experimental modes that may be used for updating the building FE model.

The aim of the present paper is to introduce ground penetrating radar (GPR) tests as a support of the structural identification for complex structures as the bell tower of the Cathedral of Trani (Bari, Italy); in particular, the structural identification has been performed by means of the Operational Modal Analysis (OMA) and subsequently the identified modal parameters have been utilized for the updating of a Finite Element model. Nevertheless, considering that the walls of the tower are composed by layers of different thickness and properties, the updating procedure has been implemented matching the results of the GPR tests. The possibility of using the GPR technology for foreseeing the internal composition of the building walls is here discussed and analysed together with the description of all the phases of dynamic identification and tower model updating.

This paper describes a study carried out on the masonry bell tower of “Annunziata” (Corfu, Greece) , which shows a high damaged scenario and, consequently, a high vulnerability to dynamic and seismic forces. It presents the experimental investigations and results useful to define the finite element model of the tower. The monitoring system consists of several elements properly connected: in total twenty-four accelerometers have been positioned, eight for each of the three floors, according to the orthogonal directions x and y. This configuration has been also determined by the many operative problems about the position of the instrumentation due to the limited accessibility of the structure, both for the main access and to reach the top. It is important to emphasize that the data obtained are not connected to external events detected during the acquisitions, so it is possible to identify with a certain confidence the first six frequencies of the tower and their corresponding mode shapes.

Il lavoro esamina le possibilità di utilizzo del laterizio rettificato ed in particolare la sua posa in opera attraverso l’innovativa tecnica del “giunto sottile”. Con il seguente studio sperimentale si è voluto inoltre investigare la possibilità di utilizzare nuovi impasti con l’aggiunta nella matrice di differenti tipologie di fibre plastiche, mono e plurifilamento, con lo scopo di migliorare l’azione di cucitura all’interno del giunto, in modo da modificare i meccanismi di rottura e fornire resistenze aggiuntive al binomio laterizio-collante

The purpose of this work is to study the dynamic behavior of a pedestrian bridge in Alicante, Spain. It is a very slender footbridge with vertical and horizontal vibration problems during the passage of pedestrians. Accelerations have been recorded by accelerometers installed at various locations of the bridge. Two scenarios, in free vibration (after the passage of a certain number of pedestrians on the bridge) and forced vibration produced by a fixed number of pedestrians walking on the bridge at a certain speed and frequency. In each test, the effect on the comfort of the pedestrians, the natural frequencies of vibration, the mode shapes and damping factors have been estimated. It has been found that the acceleration levels are much higher than the allowable by the Spanish standards and this should be considered in the restoration of the footbridge.

For the seismic design of flat-bottom grain silos containing grain-like material, the Eurocode 8 suggests that the horizontal actions on the walls of the silo are evaluated under the hypotheses of (1) stiff behavior of the silo and its contents and (2) the effective mass which pushes on the walls corresponds to the whole content of the silo except the base cone with an inclination equal to the internal friction angle of the grain. This design approach seems to be over-conservative for squat silos. In a previous research work, the authors developed an analytical study, which allows for substantial reductions in the seismic actions for silos characterized by squat geometrical configuration. The analyses are developed by means of plain dynamic equilibrium considerations and by simulating the earthquake ground motion with constant vertical and horizontal accelerations and lead to the subdivision of the ensiled material into three different portions. The findings indicate that, in the case of squat silos the portion of grain mass that interacts with the silo walls turns out to be lower than the total mass of the grain in the silo. Shaking table tests are currently under development at the lab facilities of the Bristol University, under uniaxial constant, sinusoidal and earthquake input.

This document reports the results and the preliminary interpretation of an experimental test campaign devoted to the evaluation of the actual pressures induced by the ensiled grain on the walls of flat-bottom silos during an earthquake. According to Eurocode 8, the seismic design of such silos is currently developed estimating the inertia forces caused by earthquakes upon these structures using a “crude” evaluation (80% of the mass of the grain-like material multiplied by the Peak Ground Acceleration). An alternative theory has been recently developed by the authors (Silvestri et al. 2012). The analytical research work starts from all the same basic assumptions of Eurocode 8 except for the one regarding the horizontal shear forces among consecutive grains. Only this difference leads to a new physically-based evaluation of the effective mass of the grain which horizontally pushes on the silo walls. The analyses are developed by simulating the earthquake ground motion with time constant vertical and horizontal accelerations and are carried out by means of simple dynamic equilibrium equations that take into consideration the specific mutual actions developing in the ensiled grain. The findings indicate that, in case of squat silos (characterized by low, but usual, height/diameter slenderness ratios), the portion of the grain mass that interacts with the silo walls turns out to be noticeably lower than the total mass of the grain in the silo and the effective mass adopted by Eurocode 8. The main goal of the current ASESGRAM project is to experimentally verify the analytical findings obtained by the authors (Silvestri et al. 2012) regarding the actions induced by grain like material upon the walls of flat-bottom silos. In more detail, the objective of the shaking-table tests is to investigate the pressures given by a grain like material, under constant horizontal acceleration, confined in a stiff cylindrical element, in order to compare them with the analytical formulation and with the Eurocode 8 provisions. This final report contains: (a) a brief summary of the analytical theory developed by the authors; (b) the description of the silo specimen and the test instrumentation; (c) the characteristics of the materials involved in the tests; (d) the program of the experimental tests; (e) the results of the first session of tests; (f) the results of the second session of tests; (g) the results of the third session of tests; (h) a preliminary interpretation of the experimental results in order to understand the actual behaviour of the silo contacting grain-like material under various accelerated conditions; (i) some concluding remarks containing preliminary but yet clear indications regarding the behaviour of silo under dynamic base excitation.

Recycling of waste materials is, undoubtedly, one of the most important problems in the future to be solved in all possible ways. It is becoming increasingly necessary to find solutions, even original, imaginative and brilliant to be, of course, first tested before their practical application. Polietilene tereftalato (PET), for example, is a waste material that lends itself well to be reused as concrete reinforcement. In the present article the results of impact tests performed on concrete slab specimens reinforced with fibers made from waste (PET) bottles are reported. The fibers have been obtained by simply cutting the bottles and have been utilized as discrete long reinforcement of the slabs in concrete in substitution of steel bars. A test set-up and slab specimens have been designed and manufactured for the impact tests. The tests are part of an extensive investigation on the use of PET as a reinforcing material in concrete and masonry structures. The tests provided interesting results regarding the impact strength of PET reinforced concrete, suggesting a possible use of this material, in particular for those cases frequently subjected to shocks and impact forces, such as new-jersey guard-rails, road and, especially, airport pavements, wharfs. The reinforcement with PET has the advantage to be less corrosive and less expensive than reinforcement consisting of steel wire nets and carbon or glass nets, making this material more adequate for applications in presence of an aggressive environment.

The present research fits in the general thematic of the renovation of existing building with special attention to concrete structures. A series of tests have been performed with the aim to define the best solution in strengthening a deteriorated structure with a rheoplastic mortar reinforcement. Three types of possible structural reinforcing renovation on reinforced concrete pillars have been considered, with special attention to adhesion between materials with different chemical-physical and mechanical characteristics. The crack patterns obtained on the specimens have been analyzed to demonstrate the relevance of an appropriate thickness of the reinforcement to obtain an effective mechanical behavior of the reinforced concrete element over time.

The presence of infill walls, especially those made of masonry, modifies the behaviour of the structure when subjected to horizontal forces, with a significant increase of stiffness and strength. The experience gained over time has shown that this phenomenon of interaction between structure and masonry and its interpretation is very complex, and consequently difficult to predict. This paper proposes some different models able to evaluate the effect of infill masonry panels on reinforced concrete frames subject to a seismic action. The different failure-behaviour of the same structure is considered both in the case of neglecting the contribution of the external walls and in the case of appropriately consider this contribution in terms of strength to horizontal forces and collapse mechanism. Finally the results obtained from the different models assumed for the interacting tufa masonry panels are compared with the results for a similar bare frame.

The study of damage accumulation has a relevant interest in predicting the life of aerospace structures or seismic resistant structures subjected to low-cycle fatigue phenomenon. Damage indices, based on a linear accumulation rule, are presented in this paper. Documented solutions and new proposals for stationary and non-stationary processes are discussed and their accuracy is proved with numerical simulation. These damage indices take into account the randomness of the input excitation applied to the structures. The evaluation of these damage indices requires the knowledge of the statistic of the response process. For a non-stationary process the statistics of the response is calculated through evolutionary power spectral density.

Postiguet footbridge in Alicante is a very sensitive structure to vertical vibrations and it has been restored with fiber glass composite materials to improve the response to dynamic loads. This article describes the studies carried out on the walkway in the conditions prior and after to the intervention of structural restoring. This allowed identifying the characteristic parameters of the dynamic behavior of the footbridge. The values of the natural frequencies of vibration and the damping coefficients of the structure have been determined for the different modes of vibration in the two structural conditions. Operational Modal Analysis (OMA) techniques for the modal identification have been utilized and a numerical model has been built to clearly identify the vibration modes and to compare the results.

Damage detection in civil engineering structures using changes in measured modal parameters is an area of research that has received notable attention in literature in recent years. In this paper two different experimental techniques for predicting damage location and severity have been considered: the Change in Mode Shapes Method and the Mode Shapes Curvature Method. The techniques have been applied to a simply supported finite element bridge model in which damage is simulated by reducing opportunely the flexural stiffness EI. The results show that a change in modal curvature is a significant damage indicator, while indexes like MAC and COMAC – extensively and correctly used for finite element model updating - lose their usefulness in order to damage detection.

Structural systems composed of cast in situ sandwich squat concrete walls, which make use of a lightweight material (for example polystyrene) as a support for the concrete, are widely used for construction in non seismic areas or in areas of low seismicity, and appreciated for their limited constructions costs, limited installation times, great constructions flexibility and high energy and acoustic efficiency. However their seismic behaviour has not been fully investigated. In recent years, an exhaustive experimental campaign, carried out by the University of Bologna and the Eucentre labs in Pavia, was devoted to the assessment of the seismic performances of single walls and of a portion of structure through cyclic tests under horizontal loads. To validate the theoretically and partially-experimentally anticipated (through cyclic tests under horizontal loads) good seismic behaviour of cellular structures composed of cast in situ squat sandwich concrete walls, shaking table tests were performed, at the laboratory facilities of the Eucentre in Pavia, on a full-scale 3-storey structural system composed of cast-in-situ squat sandwich concrete walls (characterized by 5.50 x 4.10 meters in plan and 8.25 meters in height). This paper describes the design process of the model as it should: (i) be representative of common real built structures; (ii) be easily transportable from the construction site to the table; (iii) lead to significant results; (iv) not damage the shaking table.

This paper shows the results of an experimental analysis on the bell tower of “Chiesa della Maddalena” (Mola di Bari, Italy), to understand the structural behavior of a slender masonry structure. The research aims, through Operational Modal Analysis (OMA), to calibrate a numerical model, which assumed realistic conclusions about the dynamic behavior of the structure. The choice of using an OMA derives from the necessity to know the modal parameters of a structure with a non-destructive testing, especially in case of cultural-historical value structures. Therefore through an easy and accurate process, it is possible to acquire in-situ environmental vibrations. The data collected are very important to estimate, with true boundary conditions, the mode shapes, the natural frequencies and the damping ratios of the structure. To analyze the data obtained from the monitoring, the Peak Picking has been method applied to the Fast Fourier Transforms (FFT) of the signals, in order to identify the values of the effective natural frequencies and damping factors of the structure. Obtained the main frequencies and the damping ratios have been determined from measures at some location;, the responses have been then extrapolated and extended to the entire tower through a 3-D Finite Element Model. In this way, knowing the modes of vibration, it has been possible to understand the overall dynamic behavior of the structure.

This article shows the experimental analysis on the bell tower of “Chiesa della Maddalena” (Mola di Bari, Italy), to understand the structural behavior of a slender masonry structure. The research aims, through Operational Modal Analysis (OMA), to calibrate a numerical model, which assumed realistic conclusions about the dynamic behavior of the structure. The choice of using an OMA derives from the necessity to know the modal parameters of a structure with a non-destructive testing in case of a structure with a cultural-historical value. Therefore through an easy and accurate process, it is possible to acquire in-situ environmental vibrations. The data collected are very important to estimate, with true boundary conditions, the mode shapes, the natural frequencies and the damping ratios of the structure. The non-linear behavior of masonry structures is due to some characteristics, such as asymmetry and inhomogeneity of the masonry itself. This leads to many difficulties to provide a real and actual behavior of the whole structure that is possible only if we know the history and the technical characteristics and geometry of the structure, in order to get accurate results. In the present paper, the original bell tower is dated back to the first half of the XVII century and due to a lightning strike it was destroyed and immediately rebuilt at the end of the same century. It was built entirely in tuff stone. The only damages present are minor cracks on the keystones of the openings and on the North and South sides below the openings. The tower has a rectangular plan and it is connected to the church for about ½ of its total height, so that its total free height is about 34 m. The tower is rigidly joined on the South, West and partly the North sides, to the sidewalls of the church. In order to monitor its mechanical and dynamic properties, the tower has been instrumented with accelerometers and subjected to environmental vibrations in the N-S and E-W directions. To analyze the data (FFT) obtained from the monitoring, the Peak Picking method has been utilized, in order to identify a value of the effective natural frequencies and damping factors of the structure. Obtained the main frequencies and the modal classification at some measurable locations, these responses are then extrapolated and extended to the entire tower through a 3D Finite Element Model. In this way, knowing the modes of vibration, it will be possible to get an idea of the overall dynamic behavior of the structure.

This paper reports describes a series of shaking table tests performed at the EQUALS lab of Bristol University in the framework of the SERIES FP7 project. The experimental test campaign was devoted to the evaluation of the effective behavior of flat-bottom silos filled of grain up to a certain height under base dynamic excitation, and to the experimental verification of the results obtained in a previous analytical research work by the authors. The analyses are developed by simulating the earthquake ground motion with time constant vertical and horizontal accelerations and are carried out by means of simple dynamic equilibrium equations that take into consideration the specific mutual actions developing in the ensiled grain. Different series of tests have been performed with different heights of the ensiled material to simulate a silo more or less squat. In this paper, the silo specimen and the test instrumentation are described, and the test program and the results are presented. Strong qualitative indications are obtained which basically confirm that the wall-grain friction coefficient plays an important role in the actions at the base of the silo walls.

Il 6 Aprile 2009 un terremoto di magnitudo ML=5.8 (MW=6.3) ha colpito la città dell’Aquila, causando forti danni alle strutture dell’Università dell’Aquila. Per poter restituire alla città, gli edifici di Ateneo nuovamente operativi, è necessario predisporre degli interventi di miglioramento del comportamento sismico, in ottemperanza alle attuali normative, nazionali ed europee, ed alle conoscenze nel settore dell’ingegneria sismica. A tal proposito, già nelle settimane successive al sisma, è stata avviata, attraverso il contributo di un gruppo multidisciplinare di docenti e ricercatori, una serie di attività coordinate di investigazione e ricerca avanzata che ha avuto come obiettivo quello di pervenire ad un progetto di miglioramento del comportamento sismico dell’Edificio A della Facoltà di Ingegneria, costituito da sette sottoblocchi, mediante l’inserimento di un sistema di controllo passivo. Le operazioni di indagine, hanno riguardato, in particolare, una campagna di misure della risposta dinamica strutturale alle azioni ambientali, svolta in collaborazione con il Politecnico di Bari, sulla base di competenze maturate congiuntamente da precedenti esperienze. Nel seguente lavoro vengono presentati i risultati di una campagna di prove dinamiche, condotte sulle sottostrutture A1 e A3. Una rete di sensori accelerometrici, composta da tredici unità, è disposta opportunamente sulla struttura e sulla facciata di ogni blocco, per registrare le accelerazioni assolute in diversi punti significativi. La registrazione dei dati è stata condotta utilizzando un sistema di acquisizione multi canale. L’orientazione di sensori uniassiali è stata scelta per registrare principalmente il moto fuori piano del telaio piano che sostiene la facciata e il comportamento roto- traslazionale della struttura. Le vibrazioni ambientali nei blocchi A1 e A3 sono state registrate per un periodo di 2100s, durante i quali sono state misurate le accelerazioni con una frequenza di campionamento di 400Hz. L’identificazione dei parametri modali è stata condotta, a partire dai dati del comportamento al rumore ambientale, utilizzando sia la procedura Enhanced Frequency Domain Decomposition (EFDD) che la procedura Stochastic Subspace Identification (SSI). Le minori frequenze naturali identificate dei blocchi A1 e A3 sono rispettivamente 3.89Hz e 2.77Hz. E’ stato trovato un sostanziale accordo tra le proprietà modali dei modelli agli elementi finiti e le caratteristiche modali identificate ed è presentata un’approfondita discussione sul ruolo delle prove dinamiche nella progettazione del miglioramento. Il documento risulta organizzato come segue: Nel paragrafo 2 viene riportata una descrizione dettagliata delle sottostrutture A1 ed A3 oggetto delle prove. Viene descritto lo stato delle strutture al momento delle prove, enfatizzando lo scenario di danno degli elementi non strutturali, i carichi agenti sulle strutture e la presenza di eventuali sistemi provvisionali, che possono rapp

In this paper dynamic identification techniques for a non-destructive evaluation of the dynamical characteristics of cultural value buildings are applied to the medieval Normand tower of Craco (Matera, Italy) that is built next to a landslide area. As a consequence the little medieval town was abandoned starting from 1968 when the effects of the landslide on the buildings were more pronounced. The tower is one of the few building still standing as it is built on a fixed stiff ground. More in detail, the paper presents the in-situ tests results and the preliminary finite element model of the tower. The tower was built in the XI century for defense against enemy attacks. It has a symmetric square plan, with dimensions 11 m x 11 m, and it is 20 m tall. Inside a cistern in reinforced concrete was placed in 1949. It has no interaction with the structure of the tower; nevertheless it makes more difficult to install the sensors of the testing set-up. The results of the experimental tests have been analyzed to estimate the modal parameters through Operational Modal Analysis. The results will give indications about the health status of the tower in order to assess its effective risk of collapse and prevent the structure from the damage due to dynamic forces and the close landslide movements.

Recycling of waste materials is one of the most important problems in the future to be solved in all possible ways. Polyethylene terephthalate (PET), for example, is a waste material that could be reused as concrete reinforcement. In the present article the results of impact tests performed on reinforced concrete specimens with fibers made from waste PET bottles are reported. The fibers have been obtained by simply cutting the bottles and have been utilized as discrete long reinforcement of specimens in concrete in substitution of steel bars. A test set-up and slab specimens have been designed and manufactured for the impact tests. The tests provided interesting results regarding the impact strength of PET reinforced concrete, suggesting a possible use of this material, in particular for those cases frequently subjected to shocks and impact forces, such as road and, especially, airport pavements, wharfs, etc. The reinforcement with PET has the advantage to be less corrosive and less expensive than reinforcement consisting of steel wire nets and carbon or glass nets.

L’isolamento di base rappresenta un’efficace strategia di protezione sismica delle costruzioni basata sul concetto di controllo passivo delle vibrazioni. Dopo anni di sperimentazioni in laboratorio e applicazioni pionieristiche, gli isolatori sismici sono oggi considerati in ogni parte del mondo alla stregua di comuni elementi strutturali cui è demandato il particolare compito di deviare l’energia in ingresso nella costruzione attraverso l’incremento del periodo proprio e dello smorzamento. Il presente libro raccoglie i principi fondamentali, i criteri di progettazione e i dettagli costruttivi indispensabili per l’impostazione e la redazione dei progetti di strutture isolate alla base. Vengono altresì illustrate e commentate le attuali prescrizioni della normativa italiana in materia (D.M. 14/1/2008 e relativa Circolare LL.PP. n. 617/2009), nonché le raccomandazioni e le regole di buona tecnica contenute nei documenti di ricerca e nelle normative straniere di comprovata validità. Il testo è arricchito da due esempi di calcolo di edifici isolati alla base, uno relativo al caso di un edificio di nuova costruzione, l’altro relativo a un intervento di adeguamento sismico di un edificio esistente. Entrambi gli esempi sono completi di analisi dei carichi, inquadramento generale dell’opera e delle scelte progettuali, verifiche strutturali e particolari costruttivi.

On the use of recycled PET for concrete reinforcement. In the present paper the results of some tests performed on concrete specimens reinforced with fibers made from waste polyethilene terephthalate (PET) bottles are reported. The tests are to be considered an approach to more extensive investigations on the use of PET as a reinforcing material in concrete and masonry structures. The tests provided interesting results, especially regarding the adherence between PET and concrete, suggesting a possible use of this material in the form of flat or round bars, or networks for structural reinforcement.

Nell’ambito della progettazione strutturale delle costruzioni civili, la conoscenza delle questioni di base relative al comportamento statico e deformativo dei telai piani costituisce per l’ingegnere l’indispensabile premessa onde gestire con competenza la scelta delle soluzioni e per un utilizzo consapevole dei software di calcolo più avanzati. Di tali questioni, attraverso l’esame di numerosi schemi con varie condizioni geometriche, di vincolo e di carico, il presente testo si propone di fornire una sistematizzazione ed una sintesi unitaria. Ogni argomento è trattato dando ampio risalto agli aspetti fisico-meccanici, e particolare attenzione è dedicata ai concetti di rigidezza e deformabilità delle aste, così come agli elementi caratterizzanti le correlazioni fra morfologia strutturale, carichi, spostamenti e sollecitazioni. I metodi classici di risoluzione sono esplicitati tramite una vasta gamma di modelli, corredati da osservazioni e valutazioni analitiche, per ciascuno dei quali sono inoltre illustrati sia gli spostamenti nodali che il diagramma qualitativo del momento flettente e la corrispondente deformata elastica.

An accurate knowledge about the dynamics of structures is definitely useful for seismic assessment and design of risk mitigation interventions. In this paper, the opportunities provided by dynamic identification techniques for the non-destructive evaluation of heritage structures are discussed with focus on the bell tower of Announziata, a masonry tower, which shows a high damaged scenario and, consequently, a high vulnerability to dynamic and seismic forces. A Finite Element (FE) numerical model has been built for research into the structural behaviour, deformation and stress distribution of the tower under static and dynamic loading. The model has been updated considering the modal parameters obtained by experimental tests carried out on the tower. The experimental measurements were difficult because of the compromised state of the building. The dynamical identification and the model updating required several assumptions of the material behaviour and properties that are not accurately available.

In the present paper, the dynamic behavior of a rolling isolation device composed of cylinders moving in between two rubber layers is studied from a theoretical point of view. The device reduces the seismic energy both by decoupling the motion of the structure from the base and for the visco-elastic behavior of the rubber (or neoprene). The behavior and the efficacy of this device is explained by relations obtained for the rolling friction coefficient vs. the rolling velocity and for the horizontal force vs. the vertical load acting on the device. Future studies will aim to determine the appropriate dimensions of the elements composing the isolator that most reduce seismic vibrations in structures.

In this paper a constitutive relation of bounded tensile strength function of the strain state of the material is proposed for tufa masonry structures with and without Fiber Reinforced Polymer (FRP) reinforcement. The fiber-reinforcement is modeled as a linear elastic material with no-compression strength. Tests have been performed to verify the proposed model and the efficacy of this structural FRP reinforcement technique for masonry. Tests have utilized brick specimens, little beam specimens and masonry panels. Results demonstrated the effectiveness of the strengthening technique and the capacity of the constitutive equation to model the behavior of more complex fiber-reinforced masonry structures.

This paper presents analytical developments devoted to the evaluation of the effective behavior of grain in flat-bottom silos during an earthquake. Based on the results achieved from this study, the paper proposes an innovative methodology for the seismic design of flat-bottom silos containing granular and grain-like materials, which allow for substantial reductions (with respect to the traditional approaches adopted by the codes) in the design seismic actions for silos characterized by squat geometrical configuration. The analyses are developed by simulating the earthquake ground motion with constant vertical and horizontal accelerations and lead to the subdivision of the ensiled material into three different portions (depending on the interaction with the container) by means of plain dynamic equilibrium considerations that take into consideration the specific mutual actions developing in the ensiled grain. The findings indicate that, in the case of squat silos (characterized by low, but usual, height/diameter slenderness ratios), the portion of grain mass that interacts with the silo walls turns out to be noticeably lower than the total mass of the grain in the silo.

The following research presents the numerical and experimental results obtained on a reduced scale steel model of a medium-rise building structure dynamically protected with energy dissipaters. The steel-steel friction dissipates energy as the structure undergoes interstory drifts. A preliminary numerical analysis is performed to determine the best position of the friction dampers in the longitudinal frames. All the nodes of the numerical model have been assumed with the same bending stiffness. Shaking table tests have been performed, both in random vibration tests (to determine the natural periods and the dynamic characteristics of the model) and in earthquake simulation tests (to study the dynamic behaviour of the model with and without dampers). The results have been compared to those achieved during a previous experimental study based on the same model protected with only one friction damper for each longitudinal frame.

Several steel moment-resisting framed buildings were seriously damaged during Northridge (1994); Kobe (1995); Kocaeli, Turkey (1999), earthquakes. Indeed, for all these cases, the earthquake source was located under the urban area and most victims were in near-field areas. In fact near-field ground motions show velocity and displacement peaks higher than far-field ones. Therefore, the importance of considering near-field ground motion effects in the seismic design of structures is clear. This study analyzes the seismic response of five-story steel moment-resisting frames subjected to Loma Prieta (1989) earthquake—Gilroy (far-field) register and Santa Cruz (near-field) register. The design of the frames verifies all the resistance and stability Eurocodes’ requirements and the first mode has been determined from previous shaking-table tests. In the frames two diagonal braces are installed in different positions. Therefore, ten caseswith different periods are considered. Also, friction dampers are installed in substitution of the braces. The behaviour of the braced models under the far-field and the near-field records is analysed. The responses of the aforementioned frames equipped with friction dampers and subjected to the same ground motions are discussed. The maximum response of the examined model structures with and without passive dampers is analysed in terms of damage indices, acceleration amplification, base shear, and interstory drifts.

In this chapter, a new seismic protection device is proposed. It is designed to dissipate the energy entering a structure subject to seismic action through the activation of hysteresis loops of the material that composes it. These devices are characterized by a high capacity to absorb the seismic energy and the ability to concentrate the damage on it and, consequently, to keep the structure and the structural parts undamaged. Moreover, after a seismic event they can be easily replaced. In particular, this chapter proposes a new shear device that shows the plasticity of some areas of the device at low load levels. In order to maximize the amount of dissipated energy, the design of the device was performed by requiring that the material be stressed in an almost uniform way. In particular, the device is designed to concentrate energy dissipation for plasticity in the aluminum core while the steel parts are responsible to make stiffer the device, limiting out-of-plane instability phenomena. The geometric configuration that maximizes the energy dissipation has been determined using a structural optimization routine of finite element software.

In the present paper the results obtained from a campaign of ambient vibration acceleration measurements conducted on the damaged Engineering Faculty Edifice A of the University of L’Aquila are reported. Through the collected data, the modal parameters of the structure are identified by two output-only procedures. Based on design drawings and destructive material testing, finite element models have been realized for all the substructures composing the building. Damage observation and measured responses have been used to search through engineering judgement a reasonable agreement between the identified modal models and the spectral properties of finite element models. The reduced confidence on the main dynamic characteristics of the structural system has supported the design of a dissipative interconnections of adjacent substructures to enhance the overall seismic structural behaviour.

Knowledge of the dynamic behavior of complex buildings subjected to near-fault earthquakes may be enriched by valuable information obtained through rapid on-site dynamic testing to aid in the design of appropriate retrofitting interventions. Through a case study, the paper demonstrates the enhancement in comprehension of the structural behavior obtained by means of a two-day testing campaign conducted on a complex building of the Engineering Faculty, Edifice A, which was heavily damaged in the 2009 L’Aquila earthquake. The on-site testing was carried out with a network of thirteen accelerometers opportunely located to identify the dynamic characteristics of the structure by means of ambient noise induced vibration. Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) output only-procedures were both used to identify the main modal parameters of two substructures of the building. The modal model was used to update a finite element numerical model representing small amplitude vibrations of the damaged structures. The direct comparison of the identified modal models with finite element models, in which damaged member locations are determined by on-site visual observations, has permitted to identify a model representative of the structural behavior of the building in the immediate post-earthquake conditions.

As part of the research on fiber-reinforced concrete, the results of some tests for an approach to a broader testing on the possibility of using fibers from polyethylene terephthalate (PET) bottles to increase the ductility of the concrete are reported. The fibers are simply cut from waste plastic bottles reducing, in this way, the manufacturing costs of recycled PET fiber-reinforced concrete. The aim of this paper is to explore the possibility of re-cycling a waste material that is now produced in large quantities, while achieving an improvement of the ductility of the concrete.

This paper presents analytical developments devoted to the evaluation of the effective behaviour of grain in flatbottom silos during an earthquake. Based on the results achieved from this study, the paper proposes an innovative methodology for the seismic design of flat-bottom silos containing granular and grain-like materials, which allow for substantial reductions in the design seismic actions for silos characterized by squat geometrical configuration. The analyses are developed by simulating the earthquake ground motion with constant vertical and horizontal accelerations and lead to the subdivision of the ensiled material into three different portions by means of plain dynamic equilibrium considerations that take into consideration the specific mutual actions developing in the ensiled grain. The findings indicate that, in the case of squat silos the portion of grain mass that interacts with the silo walls turns out to be noticeably lower than the total mass of the grain in the silo.

Structural systems composed of cast in place sandwich squat concrete walls, which make use of a lightweight material (for example polystyrene) as a support for the concrete, are widely used for construction in non seismic areas or in areas of low seismicity, and appreciated for their limited constructions costs, limited installation times, great constructions flexibility and high energy and acoustic efficiency. If these cast-in-place squat concrete walls are assembled with appropriate connections, a cellular/box behavior of the structural system is obtained which leads to high strength resources (which allows not to use the post-elastic behavior and the ductility resources) and high torsional stiffness. In recent years, from an exhaustive experimental campaign it has been possible to obtain the structural performances of single panels composed of cast-in-place sandwich squat concrete walls. A series of shaking table tests have been carried out at the EUCENTRE in Pavia. The structural specimen which has been tested is a full-scale 3-storey structural system composed of cast-in-place squat sandwich concrete walls characterized by 5.50 x 4.10 meters in plan and 8.25 meters in height. Shaking table tests have been developed to validate the theoretically and partially-experimentally anticipated (through cyclic tests under horizontal loads) good seismic behavior of cellular structures composed of cast in place squat sandwich concrete walls.

In the last few decades, the use of cast in situ reinforced concrete sandwich panels for the construction of low- to mid-rise buildings has become more and more widespread due to several interesting properties of this construction technique, such as fast construction and high thermal and acoustic performances. Nonetheless the level of knowledge of the structural behavior of systems made of squat reinforced concrete sandwich panels is still not so consolidated, especially with reference to the seismic response, due to the lack of experimental studies. In recent years, while various experimental tests have been conducted on single panels aimed at assessing their seismic capacity, only few tests have been carried out on more complex structural systems. In this paper, the experimental results of a series of shakingtable tests performed on a full-scale 3-storey building are presented in detail. The main goal is to give to the scientific community the possibility of develop independent interpretation of these experimental results. An in-depth interpretation of the discrepancies between the analytical predictions and the experimental results is beyond the objective of this paper and is still under development. Nonetheless, preliminary interpretations indicate that both the stiffness and the strength of the building under dynamic excitation appear quite superior with respect to those expected from the results of previous pseudo-static cyclic tests conducted on simple specimens.

The results of bending tests up to failure of pre-stressed slab beams, fitted and not fitted with concrete casting, pre-emptively subjected to high temperatures, provide a useful contribution to the study of the fire behavior of the structural elements regarded. Comparisons are made with similar beams not previously subjected to fire tests. The results obtained are interesting in evidencing the mechanical characteristics that can be more affected by fire in the two beam typology tested.

The present paper analyses the behaviour of moment resisting frames in reinforced concrete subject to earthquakes recorded in near-field areas. In these areas, the signals show impulsive-type accelerograms, with velocity and displacement peaks higher than in far-field zones especially for the fault-normal component of the ground motion velocity in the direction of propagation of the wave, which shows large-amplitude pulses. In the following, seven near-field signals scaled in agreement with the design spectrum of the Italian code (NTC, 2008) have been adopted to perform a nonlinear analysis on a six-story frame. The response has also been determined for the same frame protected once with hysteretic-type energy dissipaters and once with base isolators. The aim of the present study is to acquire quantitative knowledge on the near-field ground motion effects on frame buildings and on their damage also in the presence of passive seismic protection systems

I sistemi strutturali costituiti da pareti tozze in c.a. gettate in opera, che utilizzano un materiale leggero (per esempio il polistirene) come supporto per il calcestruzzo sono stati ampiamente utilizzati nel corso degli anni per realizzare costruzioni in zona non sismica o in zona di bassa sismicità; essi sono stati apprezzati per il moderato costo di costruzione, i limitati tempi di messa in opera, la grande flessibilità costruttiva e l’elevata efficienza termoacustica. Nonostante ciò, il comportamento sismico di tali strutture non è stato ancora pienamente studiato. La prova su tavola vibrante che sarà condotta presso il Laboratorio dell’Eucentre di Pavia su una struttura a tre piani in scala reale a pareti tozze di tipo sandwich caratterizzata da una pianta di dimensioni pari a 5,50 m x 4,10 m e da un’altezza di 8,25 m, si pone come obiettivo quello di verificare il buon comportamento sismico (già anticipato analiticamente e sperimentalmente) di queste strutture. Nel presente articolo saranno illustrati i primi risultati relativi alla progettazione dell’edificio modello. Applicando le formule analitiche messe a punto dagli autori per la progettazione di tali strutture nei confronti delle azioni orizzontali sono state valutate le accelerazioni spettrali in corrispondenza delle quali vengono raggiunti i possibili meccanismi di crisi della struttura.

This paper describes the results from a series of shacking table tests conducted on a full-scale reinforced concrete building. The specimen was a 3-storey structural system composed of squat cast-in-situ sandwich concrete walls with 5.50 m length, 4.10 m width and 8.25 m height. Shaking table tests were performed to validate the theoretical formulations which had been already developed by the authors in order to predict the seismic capacity of the tested structural systems. Both white noise and seismic tests were performed increasing the seismic intensity between 0.05 to 1.2 g. At the end of the experimental campaign, the building was essentially undamaged. From the white noise tests, a slight increase in the fundamental period was found, indicating some degradation. Although a meaningful interpretation of the test results in still under development, the structural system showed an impressive seismic capacity.

This paper reports describes a series of shaking table tests performed at the EUCENTRE lab in the framework of the SERIES FP7 project. This paper presents the works developed to design a test at the, for the evaluation of the maximum capacity of a 3-storey building under an earthquake. The structural system of this building is composed of cast in-situ sandwich squat reinforced concrete walls which make use of poly-styrene as a support for the concrete. The purpose of this test is to verify the dynamic behavior of this structural typology under earthquake loads. The structural specimen which will be tested is a structural system composed of cast-in-situ squat sandwich concrete walls characterized by 5.50 x 4.10 m in plan and 8.25 m in height. The input for the simulation will be the Montenegro earthquake in April of 1979. The construction of this building was developed out of the main laboratory; it was lifted and pulled inside using hydraulic jacks and a roller system. A bracing system was developed to assure the integrity of the structure during all the process. This chapter presents some preliminary test results.

This article demonstrates what influence has a change in production technology on mechanical properties of rubber testing samples. It compares two basic production technologies – compression molding and injection molding. The aim of this research is to show and evaluate to what extent the mechanical properties are influenced by the used production technology and to quantify this potential difference on the basis of mechanical tests.

In the present paper, the dynamic behaviour of a rolling isolation system composed of cylinders moving in between two rubber layers is studied by mean of characterization tests. The device reduces seismic energy both by decoupling the motion of the structure from the base and by the presence of rubber (or neoprene) supposed with a viscoelastic behaviour. From a preliminary design it has been determined the appropriate dimensions of the device and the details to link the device to the testing equipment. Considerations have been drawn from the tests results on the behaviour and the efficacy of this new device.

The present paper has the purpose to compare the shear strength obtained using the values proposed by the code for a level of knowledge LC3 [1,2] of a masonry structure with those experimentally obtained from the mechanical tests with flat jacks and the compression tests on stone elements. The shear strength criterion of Mohr-Coulomb has been utilized, applying for the cohesion and friction angle the values obtained by the non-linear criterion of Hoek-Brown for rock masses [3]. For the last criterion an analogy has been assumed between rock mass and masonry; it has been properly adapted to the specific case of masonry structure examined in the paper.

The present document reports the outcomes of an experimental test campaign for the assessment of the seismic behaviour of a full-scale 3-storey structural system composed of cast-in-situ squat sandwich concrete walls. The structural system, which has been developed by the Italian company Nidyon Costruzioni S.p.a. and referred to as Nidyon NYSP, is based on the production and use of prefabricated modular pre-reinforced polystyrene panels (which therefore will be simply referred as modular panels) which act as support for the placing of the structural concrete (typically shotcrete). Modular panels are assembled at the site in order to obtain the so called support wall. Once the support walls are set in place, two layers of concrete (each one of about 40 mm in thickness) are sprayed on each side to obtain the r/c wall. Nidyon NYSP is characterized by limited costs, fast construction, high thermal and acoustic performance and is typically used for the construction of mid-rise residential building. The final structural solution is the result of a comprehensive research work ,started at the beginning of ‘90s, carried out by the University of Bologna aimed at characterizing both the monotonic in plane and out of plane static behaviour and the in-plane cyclic behaviour of single walls (with and without opening) and coupled walls. The results of the work lead to the formulation of analytical relationship (validated through pseudo-static cyclic tests) for the prediction of the seismic behaviour of the system. In order to verify the actual seismic behaviour of the above structural system shacking table tests on a full-scale prototype building, representative of a mid-rise residential building, appears the most meaningful test typology. It should be noted that, while the description of the construction system and the results of the experimental tests are specifically referred to the products of Nidyon Costruzioni S.p.a. (Rimini,Italy); nonetheless, the observations and the conclusions may be extended to structural systems having similar characteristics.

Il restauro ad Alicante, in Spagna, di una passerella relativamente snella particolarmente incline alle vibrazioni verticali e, in misura minore, a quelle laterali, indotte dalla azione dei pedoni, restaurata con materiali compositi in fibra di vetro, sono stati il motivo di uno studio completo del comportamento dinamico prima del rinforzo, al fine di valutare le variazioni di tale comportamento una volta restaurata. Questo articolo descrive gli studi effettuati nella fase antecedente al rinforzo, e i relativi risultati, che permettono di caratterizzare il comportamento dinamico reale della passerella pedonale. Queste prove hanno consentito di identificare i parametri modali e il fattore di smorzamento per i principali modi di flessione. È stato inoltre possibile identificare gli elevati valori di accelerazione verticale e un evidente effetto di risonanza dovuto sia all’elevata snellezza, sia alla particolare geometria della passerella pedonale, fattori che dovranno essere analizzati in modo approfondito dopo la ristrutturazione della passerella.

In the present paper the results of some tests performed on concrete specimens reinforced with fibers made from waste polyethilene terephthalate (PET) bottles are reported. The fibers have been obtained by simply cutting the bottles; the fibers are then added to the mix concrete or they are used as discrete reinforcement of specimens and little beams in substitution of steel bars. The tests are to be considered as an approach to a more extensive investigation on the use of PET as a reinforcing material for concrete and masonry structures. The results that have been obtained are very interesting, especially regarding the adherence between PET and concrete, suggesting a possible use of this material in the form of flat or round bars, or networks for structural reinforcement.

Time-dependent phenomena as shrinkage and creep in concrete or relaxation in steel, deeply influence 26 the stress and strain patterns of prestressed concrete bridges. Such phenomena are more relevant for 27 staged-constructed bridges, in which a change of the static scheme occurs by the addition of restraints 28 to the initial scheme. The aim of this paper is to develop an approximated procedure allowing to calculate 29 the long-term stress and strain patterns in modern prestressed composite structures. The method is 30 based on the introduction of a suitable number of time intervals depending on the constructive phases 31 of the bridge; then, for each time step, the influence functions of the linear viscosity coefficient are 32 defined together with the variation of this coefficient. The further introduction of the hypotheses of linear 33 behavior of the viscous-elastic strain distribution and the external loads concentrated at the end of each 34 time step, leads to a significant simplification of the problem presented above. The proposed calculation 35 model is used to determine the stress–strain state of the ‘‘Quattroquerce Viaduct’’ located on the highway 36 ‘‘A3’’ Salerno-Reggio Calabria, Italy.

Seismic isolator (1) comprising at least a first cradle (11/12) and a second cradle (12/13), the cradles being positioned one over the other, each cradle housing respectively a first (R1A - R1C) and a second (R2A - R2C) group of rollers, wherein axes of rotation of the rollers of the first group are mutually parallel and lying in a first plane, wherein axes of rotation of the rollers of the second group are mutually parallel and lying in a second plane parallel to the first plane, and wherein the axes of rotation of the rollers of the first group are offset with respect to the axes of rotation of the rollers of the second group.

Concrete component comprising at least one reinforcing element in plastic material of elongated shape having a size greater than the other two, characterized by a length of the reinforcement comparable with the length of the artefact measured in the direction in which the reinforcing element is positioned. The section of the reinforcement is such as to ensure a bending strength sufficient to support its own weight in the process of positioning, and a constant section along the longitudinal direction, so as to allow the manufacturability by extrusion of the reinforcing element.