Fabrizio GARA

Pubblicazioni

Fabrizio GARA

 

181 pubblicazioni classificate nel seguente modo:

Nr. doc. Classificazioni
127 4 Contributo in Atti di Convegno (Proceeding)
44 1 Contributo su Rivista
6 2 Contributo in Volume
3 5 Altro
1 3 Libro
Anno
Risorse
2021
Finite elements for higher order steel–concrete composite beams
APPLIED SCIENCES
Autore/i: Gara, F.; Carbonari, S.; Leoni, G.; Dezi, L.
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents finite elements for a higher order steel–concrete composite beam model developed for the analysis of bridge decks. The model accounts for the slab–girder partial interaction, the overall shear deformability, and the shear‐lag phenomenon in steel and concrete components. The theoretical derivation of the solving balance conditions, in both weak and strong form, is firstly addressed. Then, three different finite elements are proposed, which are characterised by (i) linear interpolating functions, (ii) Hermitian polynomial interpolating functions, and (iii) interpolating functions, respectively, derived from the analytical solution expressed by means of exponential matrices. The performance of the finite elements is analysed in terms of the solution con-vergence rate for realistic steel–concrete composite beams with different restraints and loading con-ditions. Finally, the efficiency of the beam model is shown by comparing the results obtained with the proposed finite elements and those achieved with a refined 3D shell finite element model.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286916 Collegamento a IRIS

2021
Post-Earthquake Damage and Vulnerability Assessment of Churches in the Marche Region Struck by the 2016 Central Italy Seismic Sequence
INTERNATIONAL JOURNAL OF ARCHITECTURAL HERITAGE
Autore/i: Canuti, C.; Carbonari, S.; Dall'Asta, A.; Dezi, L.; Gara, F.; Leoni, G.; Morici, M.; Petrucci, E.; Prota, A.; Zona, A.
Classificazione: 1 Contributo su Rivista
Abstract: This paper analyses the observational damage from post-earthquake investigations carried out on churches of the Marche Region struck by the 2016 Central Italy seismic sequence. Such seismic activity seriously damaged many historical buildings and particularly churches, due to their intrinsic inability to develop an efficient box-like resisting mechanism. After the mainshocks, teams of structural engineers were involved in the assessment of damage of churches and in the evaluation of their usability. Collected data are processed in this work to give insight into the occurred damage and to evaluate the vulnerability of the religious buildings of the Region. To this purpose, an architectural background is firstly provided to allow for a classification of the sample, then, the most recurring damage mechanisms are identified, and a global damage index of each church is computed. The distribution of the damage over the Region is commented, as a function of the macro-seismic intensity and other important factors affecting the seismic response. Finally, the overall damage of the sample is compared to that estimated through empirical models available in the literature and comparisons with the results of previous studies are provided.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269907 Collegamento a IRIS

2021
Monitoring the Modal Properties of an RC School Building during the 2016 Central Italy Seismic Swarm
JOURNAL OF STRUCTURAL ENGINEERING
Autore/i: Gara, F.; Arezzo, D.; Nicoletti, V.; Carbonari, S.
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents results from the dynamic monitoring of a reinforced concrete school building located in Camerino (central Italy) during the seismic swarm following the first main shock of the Central Italy earthquake that occurred in August 2016. After the main shock of August 24th, ambient vibration tests were executed on the building to identify its modal dynamic behavior, which was assumed as benchmark to study changes in the structural response because of the subsequent events. A three-day dynamic monitoring was then performed with the aim of investigating changes in the dynamic behavior of the building subjected to ambient and seismic excitations. A procedure to identify the nonlinear response of the structure subjected to seismic events is presented, starting from an optimization methodology that permits the identification of the structure dynamics within time windows in which the building dynamic behavior can be considered linear time-invariant. Data show the variability of the modal properties, resonance frequencies, and damping ratios of the building, with the earthquake intensity.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/289951 Collegamento a IRIS

2021
Dynamic behavior of soil-foundation-structure systems subjected to scour
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: Antonopoulos, C.; Tubaldi, E.; Carbonari, S.; Gara, F.; Dezi, F.
Classificazione: 1 Contributo su Rivista
Abstract: Earthquake and scouring are the leading causes of bridge failure worldwide, resulting not only in casualties and fatalities but also in enormous societal and economic losses. A great number of bridges in earthquake-prone countries cross rivers and have shallow foundations, which renders them highly vulnerable to the combined effects of earthquake and flood-induced scour. Thus, the research on the dynamic response of bridges with shallow foundations under scour and earthquake hazards is timely and imperative. This study investigates the problem through the development of a numerical model for evaluating the effect of scour on the impedance functions of a massless rigid strip foundation resting on a homogenous elastic half-space. The developed impedance functions are then used in an extensive parametric study analyzing the changes of the fundamental frequency of bridge piers for different combinations of the geometrical and mechanical properties of the soil-structure-foundation system. The study results shed light on the effects of scour on the dynamic properties and fundamental frequency of vibration of bridges with shallow foundations and have important implications on the development of inverse techniques for scour identification based on the evaluation of the changes in the bridge modal properties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/293282 Collegamento a IRIS

2021
Dynamic monitoring of buildings as a diagnostic tool during construction phases
JOURNAL OF BUILDING ENGINEERING
Autore/i: Nicoletti, V.; Arezzo, D.; Carbonari, S.; Gara, F.
Classificazione: 1 Contributo su Rivista
Abstract: The paper discusses the usefulness of the dynamic characterization of buildings based on the use of ambient vibration tests at different construction phases. The proposed experimental procedure, integrated with more conventional non-destructive in-situ tests for the estimation of the material mechanical properties, foresees the monitoring of the evolution of the building modal properties during the main construction phases. The monitoring makes it possible to assess the correctness of the construction through comparison with expected trends, and to consider possible countermeasures in case of unexpected behaviours. A case study, monitored during its construction, is presented to show the additional value of information obtained from the proposed experimental approach: (i) tests on the bare frame can be adopted to validate the design numerical model of the structure, in which non-structural elements are neglected in performing ultimate limit state verifications, (ii) the proposed monitoring allows the identification of the infills contribution on the building dynamics, providing useful information to address the interaction problem between structural and non-structural elements that may be detrimental at ultimates, and (iii) trends of resonance frequencies during the construction, validated through numerical applications, constitute an important tool for interpreting data from structural health monitoring system, as well as to establish alert thresholds of demand parameters (e.g. relevant to the building occupancy or structural damage).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/293681 Collegamento a IRIS

2020
Expeditious methodology for the estimation of infill masonry wall stiffness through in-situ dynamic tests
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Nicoletti, V.; Arezzo, D.; Carbonari, S.; Gara, F.
Classificazione: 1 Contributo su Rivista
Abstract: In this paper a procedure to experimentally estimate the stiffness of masonry internal partitions and infill walls is proposed with the aim of providing a practical tool to reduce uncertainties in the finite element modelling of frame buildings when partitions and infills must be included. The proposed methodology, based on in-situ impact load tests and numerical modelling, is presented. The methodology is validated through an experimental campaign on a laboratory mock-up and applied to a real reinforced concrete frame building. The proposed methodology revealed capable to provide a very accurate estimate of the infill stiffness to be adopted in the building modelling.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/283984 Collegamento a IRIS

2020
Measurements of ambient vibrations for a cable-stayed bridge including the soil-foundation system
Proceedings of the International Conference on Structural Dynamic , EURODYN
Autore/i: Nicoletti, V.; Arezzo, D.; Carbonari, S.; Dezi, F.; Gara, F.
Editore: European Association for Structural Dynamics
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper deals with the dynamic characterization of a cable-stayed steel-concrete composite bridge located on the Saline river, close to Pescara in central Italy, carried out during the static proof load test. The bridge is 189 m long and is composed by 4 inclined steel pipe pylons that sustain a steel-concrete composite deck by means of 40 stay cables. During the proof test, an extensive experimental campaign is carried out to check the overall structural performance before the bridge openings to traffic. In detail, the main girder deflections, the axial loads on strands, the pylons displacements, and the bearings displacements were monitored through conventional and non-conventional techniques, such as the laser scanner technique. In addition, an accelerometer array is installed during the proof test to evaluate the dynamic characteristics of the structure in its loaded and unloaded conditions through ambient vibration measurements. Sensors are positioned on the deck, on two pylons and on the foundation system, in order to characterize the whole structural dynamic behavior, including the contribution of the soil-foundation compliance. With reference to the unloaded bridge, the latter issue is analyzed in this paper, focusing on the different restraint condition exerted by the soil-foundation system of the pylons, because of the different embedment of the reinforced concrete basements. It is shown that the soil-foundation compliance has greater effects on higher modes for the bridge at hand and that possible non-symmetries due to the different foundation degree of restraint can be suitably captured through ambient vibration tests. Data from experimental tests are crucial not only to check consistency between the design and the real structure before the opening to traffic, but also to calibrate refined finite element models to be used for the structural health monitoring of the bridge. In this sense, a reliable evaluation of the contribution of the soil-foundation system is mandatory, considering that the bridge, having foundations located in the riverbed, is prone to the scour hazard.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287438 Collegamento a IRIS

2020
Static and dynamic testing of the “Filomena Delli Castelli” bridge
Belgian, Dutch and French National Groups of IABSE – Young Engineers Colloquium
Autore/i: Innocenzi, Raoul Davide; Carbonari, Sandro; Gara, Fabrizio; Dezi, Luigino
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper describes the static and dynamic testing of the “Filomena Delli Castelli”cable-stayed bridge over the Saline River, in the Pescara province (Italy), having main span of 103.4 m and total length of 188.6 m.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/291654 Collegamento a IRIS

2020
Dynamic monitoring of bridges during static load tests: influence of the dynamics of trucks on the modal parameters of the bridge
JOURNAL OF CIVIL STRUCTURAL HEALTH MONITORING
Autore/i: Gara, F.; Nicoletti, V.; Carbonari, S.; Ragni, L.; Dall'Asta, A.
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents results of an extensive experimental campaign carried out during the construction phases of a base-isolated bridge across the Potenza river in central Italy. The structure is constituted by a half-through steel arch bridge composed by two coupled weathering steel tubular arches sustained by thirty couples of hangers and by two approaching viaducts. The bridge has a continuous twin-girder steel–concrete composite deck. During construction, impact load tests were carried out on hangers as well as on other tie elements to estimate their tension force from the relevant resonance frequencies. During the proof test, relative displacements occurred between the upper and lower plates of the seismic isolators are measured for different loading conditions. In addition, ambient vibration tests are performed during the final static load tests to investigate the bridge dynamics subjected to different loading conditions. Comparisons of test results with the numerical predicted values contributed to evaluate the consistency between the design and the real structure at different construction stages. Dynamic identification tests contributed to identify the significance of the truck–bridge interaction in the interpretation of the bridge dynamics evaluated experimentally.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273422 Collegamento a IRIS

2020
Seismic Retrofit Assessment of a School Building through Operational Modal Analysis and f.e. Modeling
JOURNAL OF STRUCTURAL ENGINEERING
Autore/i: Gara, F.; Carbonari, S.; Roia, D.; Balducci, A.; Dezi, L.
Classificazione: 1 Contributo su Rivista
Abstract: The paper deals with the dynamic characterization of a reinforced concrete (RC) frame school building in central Italy before and after the seismic retrofitting, obtained by coupling the building with an innovative patented seismic dissipative protection system. Before the retrofit, ambient vibration tests were performed to evaluate frequencies and mode shapes for developing finite-element (f.e.) models describing the school dynamic behavior in operational conditions. Several finite-element models with increasing level of detail are presented, from the bare frame model, based on the assumptions and simplifications usually adopted for design purposes, to an upgraded model taking account of secondary and nonstructural elements (e.g., internal and external walls, screeds, roofing, floor tiles, and plasters) as well as the interaction between structure and retaining walls. The latter was used to develop the design model of the seismic retrofitting system, which aims to assure the immediate occupancy of the building in the case of severe earthquakes limiting damage to nonstructural components. Tests were repeated after the retrofit to check consistency with numerical design predictions. Comparisons between experimental and numerical modal parameters are shown discussing the usefulness of ambient vibration tests.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/285066 Collegamento a IRIS

2019
Identification of infill masonry walls stiffening contribution on the dynamic behaviour of steel frames
8th IOMAC - International Operational Modal Analysis Conference, Proceedings
Autore/i: Nicoletti, Vanni; Regni, Marco; Speranza, Elisa; Arezzo, Davide; Carbonari, Sandro; Gara, Fabrizio
Editore: International Operational Modal Analysis Conference (IOMAC)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper deals with the influence of infill masonry walls on the dynamic behaviour of steel structures. The research is based on the experimental and numerical results obtained for a real scale laboratory mock-up, consisting of a one-storey two-bays steel-concrete composite frame. Ambient vibration tests followed by impact load tests were performed after the construction of the IMWs to estimate the dynamic properties of the entire structure and to investigate changes of modal parameters (natural frequencies and mode shapes) due to the contribution of the non-structural components. Furthermore, impact load tests were performed on some IMWs to identify their out-of-plane modal parameters; finally, a methodology to estimate parameters for a 2D modelling of the IMWs is proposed and validated. The numerical results show a very good agreement with the experimental ones, proving the reliability of the estimated IMWs stiffnesses through the proposed procedure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267569 Collegamento a IRIS

2019
Experimental assessment of the expected impact of a bridge seismic retrofit through ambient vibration tests
8th IOMAC - International Operational Modal Analysis Conference, Proceedings
Autore/i: Minnucci, Lucia; Regni, Marco; Speranza, Elisa; Carbonari, Sandro; Gara, Fabrizio
Editore: International Operational Modal Analysis Conference (IOMAC)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents and discusses results of ambient vibration tests performed on the Moscosi Bridge in Cingoli (Italy) before and after the execution of seismic retrofitting works. The aim of the first tests is to evaluate the dynamic parameters of the bridge, such as the eigenfrequencies, the mode shapes and the relevant modal damping ratios, in order to build up a numerical model and, through it, to predict the behaviour of the bridge after the interventions. The dynamic characterization of the bridge is obtained through the measurements of ambient vibrations, which are processed with the Covariance-driven Stochastic Subspace Identification. The information derived by the calibrated model are compared with the results of a second ambient vibrational measurement campaign, and the effectiveness of the retrofit is assessed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267570 Collegamento a IRIS

2019
An integrated permanent dynamic monitoring system of a tall building in central Italy
8th IOMAC - International Operational Modal Analysis Conference, Proceedings
Autore/i: Arezzo, Davide; Regni, Marco; Carbonari, Sandro; Gara, Fabrizio
Editore: International Operational Modal Analysis Conference (IOMAC)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents results of the dynamic monitoring of a 10-storey r.c. tower in central Italy, focusing on the effects of ambient conditions. The installed monitoring system consists of a set of three accelerometers located on the last floor of the tower, including a velocimeter located at the foundation level and an acquisition software that, through a specifically developed algorithm based on operational modal analysis techniques, automatically extracts the modal parameters of the building from the accelerometric recordings. Ambient registrations derive from a weather station installed on the roof of the tower. Effects of the ambient parameters on the dynamic properties of the building are presented and discussed. Moreover, the building response to low intensity seismic events registered during the monitoring period is compared with that obtained from a calibrated numerical model by applying at the base the input registered by the velocimeter.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267568 Collegamento a IRIS

2019
Evaluation of dynamic soil-pile interaction based on both full scale in situ tests and numerical simulations
Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions
Autore/i: Dezi, Francesca; ROIA, DAVIDE; Chiara Capatti, Maria; CARBONARI, Sandro; GARA, Fabrizio; Leoni, Graziano; Morici, Michele
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents some comparisons between results obtained by full-scale experimental dynamic tests and numerical simulations for the evaluation of the dynamic behaviour of soil-pile foundation systems. Two experimental campaigns were considered for this scope: one conducted on vibro-driven steel pipe piles in nearshore environment and the other on vertical injected and not injected micropiles in an alluvial silty deposit. Experimental cam-paigns include ambient vibration and impact tests, as well as snap back and forced vibra-tion tests. A numerical procedure, developed to study the kinematic and inertial interaction of pile foundations in horizontally layered soil profiles, was applied to predict the re-sponse of the 3 types of piles realized in different soil deposits. The primary objective of the comparisons was to assess the accuracy of the numerical procedure in predicting the dynamic response of the pile-foundation system varying the pile construction method and soil nature surrounding the pile shaft.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267572 Collegamento a IRIS

2019
Field tests on a soil-foundation-structure system subjected to scour
Atti del XVIII Convegno ANIDIS L'ingegneria sismica in Italia
Autore/i: Tubaldi, Enrico; Lupo, Rosa; Mitoulis, Stergios; Argyroudis, Sotiris; Gara, Fabrizio; Ragni, Laura; Carbonari, Sandro; Dezi, Francesca
Editore: Pisa University Press srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Earthquakes and foundation scour are the major causes of bridge failure worldwide. Many bridges in earthquake-prone countries have shallow foundations, whose stability and seismic vulnerability can be significantly undermined by flood-induced scour. This article provides the first results of the “DYMOBRIS” project (DYnamic identification and MOnitoring of scoured BRIdgeS under earthquake hazard), a H2020-SERA EU-funded project aiming at i) developing a methodology for non-invasive detection of scour in bridges with shallow foundations based on vibration monitoring, and ii) quantifying the effects of scour on the seismic vulnerability of these Soil-Foundation-Structure (SFS) systems. The experimental campaign involves various tests, from ambient vibration to force vibration, on the EuroProteas prototype under different scour conditions. The preliminary finite element models developed for defining the scour profile to be imposed in the in-field tests are presented here, together with some results concerning the effects of scour on the SFS dynamic properties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269908 Collegamento a IRIS

2019
Risultati del monitoraggio dinamico di un edificio scolastico a Camerino a valle del sisma del centro Italia dell’agosto 2016
Atti del XVIII Convegno ANIDIS L'ingegneria sismica in Italia
Autore/i: Arezzo, Davide; Speranza, Elisa; Carbonari, Sandro; Gara, Fabrizio
Editore: Pisa University Press srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Il lavoro presenta i risultati del monitoraggio dinamico di un edificio scolastico situato a Camerino (MC), durante la sequenza sismica che ha colpito l’Italia centrale nel 2016. L’edificio ospita il liceo Classico e Scientifico “Varano” ed è situato nel centro storico di Camerino; si tratta di un fabbricato con struttura a telaio in cemento armato e tamponature in laterizio realizzato negli anni ’60 e adeguato sismicamente nel 2013 con il sistema delle Torri Dissipative. Nel 2016, a valle del sisma del 24 agosto, è stato installato sull’edificio un sistema di monitoraggio dinamico costituito da accelerometri posizionati agli ultimi due piani della struttura e a livello delle fondazioni. Le registrazioni del moto alla base e della risposta dell’edificio ai piani superiori per effetto dei numerosi eventi sismici successivi al sisma principale e delle vibrazioni ambientali nei periodi di intervallo tra i sismi, hanno consentito di identificare i parametri modali grazie a tecniche input-output (N4SID), in occorrenza degli eventi sismici, e alle consolidate tecniche output-only (SSI), nei periodi di quiete. Ciò ha consentito di cogliere l’evoluzione delle caratteristiche dinamiche dell’edificio durante lo sciame sismico.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269911 Collegamento a IRIS

2019
Preliminary probabilistic assessment of the seismic response of link slab viaducts
Atti del XVIII Convegno ANIDIS L'ingegneria sismica in Italia
Autore/i: Minnucci, Lucia; Scozzese, Fabrizio; Carbonari, Sandro; Dall’Asta, Andrea; Gara, Fabrizio
Editore: Pisa University Press srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Recent seismic events occurred in Central Italy drew the attention towards the resilience of the Italian road network, which is characterised by a significant number of old reinforced concrete bridges and viaducts. In this context, the fragility assessment of existing bridges is crucial, since their collapse or loss in functionality after earthquakes may lead to significant economic and social consequences. As a preliminary study oriented to characterizing the fragility level of the Italian bridge heritage, this work focuses on the real case study of the Chiaravalle viaduct, located in Central Italy, which may be representative of a widespread class of reinforced concrete bridges in Italy. The viaduct is a continuous multi-span bridge consisting of precast simply supported V-shaped beams connected by a continuous upper slab. A numerical model is developed in order to capture the failure mechanisms most likely to occur for this bridge typology subjected to seismic actions. A probabilistic assessment of the seismic response of the bridge is carried out by performing multiple stripe analysis (MSA), and a preliminary interpretation of the results is provided. Future studies will be aimed to the development of fragility curves, by accounting for all the relevant demand parameters and limit states.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269910 Collegamento a IRIS

2019
Influenza delle tamponature sul comportamento dinamico di strutture a telaio in acciaio: sperimentazione su un caso studio
Atti del XVIII Convegno ANIDIS L'ingegneria sismica in Italia
Autore/i: Nicoletti, Vanni; Arezzo, Davide; Carbonari, Sandro; Gara, Fabrizio
Editore: Pisa University Press srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: L’articolo riguarda un’estesa campagna sperimentale finalizzata all’analisi dell’influenza delle tamponature sul comportamento dinamico di strutture intelaiate in acciaio. La sperimentazione è stata condotta in laboratorio su un telaio in acciaio con soletta composta in c.a. e lamiera grecata, sul quale sono state eseguite prove di impatto, di vibrazione ambientale e di spinta e rilascio, per le quali vengono descritte le procedure seguite, la strumentazione adottata e i principali risultati ottenuti. Le prove sono state eseguite prima e dopo la realizzazione di tamponature leggere in laterizio forato e intonaco al fine di valutare il contributo fornito, in termini di rigidezza, sul comportamento dinamico globale del telaio soggetto ad azioni tali da mantenere la struttura e le pareti in campo elastico. Per concludere, viene presentato un confronto tra i risultati ottenuti con le diverse prove che, nonostante lascino tutte la struttura in campo elastico, sono caratterizzate da un diverso livello di eccitazione e forniscono risultati in alcuni casi piuttosto differenti.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269909 Collegamento a IRIS

2019
The significance of soil-foundation compliance on the dynamic identification of the Chiaravalle viaduct
Atti del XVIII Convegno ANIDIS L'ingegneria sismica in Italia
Autore/i: Carbonari, Sandro; Dezi, Francesca; Gara, Fabrizio; Leoni, Graziano
Editore: Pisa University Press srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper addresses the significance of soil-structure interaction on the dynamic behaviour of the “Chiaravalle viaduct”, based on ambient vibration measurements and numerical simulations through a finite element model. The viaduct is located in Central Italy and is founded on piles in an eluvial-colluvial soil deposit. Experimental modal properties are evaluated by means of the operational modal analysis on accelerometric data, and the role of soil-structure interaction in the interpretation of tests is identified by means of a refined finite element model of the viaduct. In the soil-structure interaction models the local site conditions in correspondence of each bridge pier (resulting from geotechnical and geophysical investigations) are taken into account in the definition of the soil-foundations impedances. Comparisons between the experimental and numerical results highlight the role of the pile-soil-pile interaction, the radiation problem, the pile cap embedment and the variability of the soil stratigraphy along the longitudinal direction of the viaduct in the interpretation of the experimental data.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269912 Collegamento a IRIS

2019
Dynamic identification and collapse assessment of Rubbianello Bridge
Report of IABSE SYMPOSIUM "Towards a Resilient Built Environment"
Autore/i: Ragni, L.; Scozzese, F.; Gara, F.; Tubaldi, E.
Editore: IABSE c/o ETH Zurich
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper investigates the causes of failure of Rubbianello Bridge, a multi-span masonry arch bridge located in Central Italy, which suffered the collapse of two of the seven spans due to foundation scour during a very severe flood in December 2013 and the collapse of two more spans during another major flood event in 2016. An accurate nonlinear 3D model of the bridge is developed. The elastic properties of the model are calibrated based on both material tests and an experimental campaign carried out for the dynamic identification (in terms of vibration frequencies and modal shapes) via operational modal analysis of the remaining part of the bridge. A numerical simulation of the scour hole progression is performed in order to identify the collapse mechanism of the bridge under the first major flood and estimate the level of scour that caused the bridge failure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/265467 Collegamento a IRIS

2019
Preliminary fragility analysis of a r.c. frame school building retrofitted by an external dissipative system
Atti del XVIII Convegno ANIDIS
Autore/i: Gioiella, Laura; Ragni, Laura; Gara, Fabrizio; Dall’Asta, Andrea
Editore: Pisa University Press srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Seismic events occurred in the last decade in Italy led the attention to the evaluation of the health and need of interventions on the existing school buildings heritage, whose collapse or loss in functionality after an earthquake may lead to significant economic and social losses. For this reason, this study focuses on the preliminary fragility assessment of a typical school r.c. frame building, retrofitted through an external configuration based on the use of fluid viscous dampers (FVDs). The case study is a two elevations moment resisting frame structure, built in Italy in the sixties without seismic code. The external retrofit configuration is a rocking base system consisting of a pinned-rocking braced frames equipped with fluid viscous dampers at their base. Fragility curves, built by accounting for different level of inter-storey drift and for seven intensity measures of the seismic action, provide useful insights about the efficiency and dynamic response of the r.c. frame before and after the retrofitting works.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/274077 Collegamento a IRIS

2019
Evaluation of fragility curves of a reinforced concrete viaduct in Central Italy: a preliminary analysis
Atti del 1st fib Italia YMG Symposium on Concrete and Concrete Structures
Autore/i: MINNUCCI, LUCIA; SCOZZESE, Fabrizio; CARBONARI, Sandro; Dall’Asta, Andrea; GARA, Fabrizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Recent seismic events occurred in Central Italy drew the attention towards the resilience of the Italian road network, which is characterised by a significant number of old reinforced concrete bridges and viaducts. In this context, the fragility assessment of existing bridges is crucial, since their collapse or loss in functionality after earthquakes may lead to significant economic and social consequences. As a preliminary study oriented to characterizing the fragility level of the Italian bridge heritage, this work focuses on the real case study of the Chiaravalle viaduct, located in Centre Italy, which may be representative of a widespread class of reinforced concrete bridges in Italy. The viaduct is entirely characterized by a reinforced concrete structure, with a link continuous slab on simply supported V-shaped girders. After a preliminary study on the current structural health of the bridge, a numerical model is developed in order to capture the failure mechanisms most likely to occur. Fragility curves, built by accounting for all the relevant demand parameters and limit states, provide useful insights about the main structural deficiencies of the system at hand.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/275315 Collegamento a IRIS

2019
First analysis of data concerning damage occurred to churches of the marche region following the 2016 central Italy earthquakes
BOLLETTINO DI GEOFISICA TEORICA E APPLICATA
Autore/i: Carbonari, S.; Dall'asta, A.; Dezi, L.; Gara, F.; Leoni, G.; Morici, M.; Prota, A.; Zona, A.
Classificazione: 1 Contributo su Rivista
Abstract: The seismic sequence that struck central Italy from August to October 2016 caused severe damage to many historical and artistic buildings. In particular, churches were widely affected due to the intrinsic peculiarities of their structural system, unable to develop an efficient box-like resisting mechanism. After the seismic events, teams of experts carried out a massive survey of churches to assess both the occurred damage and their usability. Teams were coordinated by the Department of Civil Protection and the Ministry of Cultural Heritage. In this paper, a methodology for processing the data recorded during the inspections of a number of churches of the Marche region is proposed and used to analyse a sample data set. Starting from the subdivision of the sampled churches into homogeneous typologies, the most recurring damage mechanisms are identified. In addition, the global damage index of each church is correlated with the relevant highest pseudo spectral acceleration at period 0.30 s registered at the site as a consequence of the main shocks; relationships between the seismic intensity and the observed damage are then derived from such a correlation. Finally, the overall damage occurred to churches of the sample is compared to that estimated through empirical models available in the literature.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269326 Collegamento a IRIS

2019
Local failure mechanisms of existing steel-concrete composite decks
Atti del XXVII CONGRESSO C.T.A.
Autore/i: Minnucci, Lucia; Carbonari, Sandro; Dezi, Luigino; Gara, Fabrizio; Dall'Asta, Andrea
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The design of Steel-Concrete Composite (SCC) bridges is usually oriented to the solution of global problems, governed by strength and ductility issues of the whole structure, while minor attention is generally given to local effects, associated with the transfer mechanisms of inertia forces from decks to substructures. However, local failure mechanisms of the deck may be of importance since they may compromise the overall response of the bridge, especially for existing bridges, designed ac-cording to lower seismic actions compared to those defined by modern codes. In this paper, the seismic response of an existing SCC bridge is investigated, focusing on the role of local failure mechanisms of the deck on the overall response of the bridge. Two local paths for the seismic action are analyzed: the first involves the shear connection through which inertia forces act-ing at the level of the concrete slab are firstly transferred to steel members; the second is represented by truss cross-beams at supports, one of the most widespread typologies for existing SCC decks, through which the shear forces are transferred to bearings and substructures. Results of seismic analyses on the selected case study are shown and discussed, highlighting the vulnerabilities of the investigated local components.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273425 Collegamento a IRIS

2019
Sustainable Engineering for Resilient Built and Natural Environments
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Alici, Antonello; Bocci, Maurizio; Bonvini, Paolo; Brocchini, Maurizio; Calamai, Alessandro; Canestrari, Francesco; Capozucca, Roberto; Carbonari, Alessandro; Carbonari, Sandro; Cardone, Fabrizio; Clementi, Francesco; Clini, Paolo; Cocchi, Giammichele; Corvaro, Sara; Darvini, Giovanna; Davì, Fabrizio; Dezi, Luigino; Di Giuseppe, Elisa; D’Orazio, Marco; Ferretti, Maddalena; Ferrotti, Gilda; Gara, Fabrizio; Giretti, Alberto; Graziani, Andrea; Lancioni, Giovanni; Lemma, Massimo; Lenci, Stefano; Lorenzoni, Carlo; Malinverni, Eva Savina; Mancinelli, Alessandro; Mariano, Fabio; Mentrasti, Lando; Mondaini, Gianluigi; Montecchiari, Piero; Munafò, Placido; Naticchia, Berardo; Postacchini, Matteo; Quagliarini, Enrico; Quattrini, Ramona; Ragni, Laura; Serpilli, Michele; Soldini, Luciano; Virgili, Amedeo; Zampini, Giovanni
Editore: Springer
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272866 Collegamento a IRIS

2019
Dynamic properties of a masonry arch bridge subjected to local scour up to failure
Proceedings of ICONHIC 2019
Autore/i: Ragni, Laura; Scozzese, Fabrizio; Gara, Fabrizio; Tubaldi, Enrico
Editore: National Technical University of Athens
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277800 Collegamento a IRIS

2019
The seismic retrofit by external dissipative systems: A case study
COMPDYN Proceedings
Autore/i: Gioiella, L.; Tubaldi, E.; Ragni, L.; Gara, F.; Dall'Asta, A.
Editore: National Technical University of Athens
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: External dissipative systems are seismic retrofit solutions for existing building frames that present some feasibility advantages with respect to more classic solutions involving dissipative devices installed within existing frames. This study analyses and compares the effectiveness of three alternative external retrofit configurations based on the use of fluid viscous dampers (FVDs) with reference to a case study involving the seismic upgrading of a typical school r.c. frame. In particular, the three considered systems are: a rocking base system consisting of a pinned-rocking braced frames equipped with fluid viscous dampers at their base, a fixed base system consisting of external fixed-base braced frames connected to the frame through dampers located at floor levels and a diagonal bracings system similar to the traditional arrangement, but installed adjacent to the frame. All the proposed retrofit solutions are analysed taking into account the non-linear behaviour of the r.c. frame building (designed with inadequate seismic detailing) and both the linear and non-linear behaviour of the FVDs. The obtained results show that all the systems are effective solutions, even if performances in terms of interstorey-drifts, absolute floor accelerations, forces and strokes of the dampers are different.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277590 Collegamento a IRIS

2019
A performance-based approach for the design of coupled dolphin-fender berthing structures
MARINE STRUCTURES
Autore/i: Carbonari, Sandro; Antolloni, Giulia; Gara, Fabrizio; Lorenzoni, Carlo; Mancinelli, Alessandro
Classificazione: 1 Contributo su Rivista
Abstract: The paper presents a performance-based approach for the design of flexible breasting dolphins equipped with marine fenders, often used in jetties belonging to offshore oil terminals. Since the distance of the breasting system to the mooring one and to the oil terminal is generally limited for serviceable and operational issues, the proposed design methodology, based on the kinetic energy approach, assumes a predetermined displacement for the dolphin, as well as a desired performance of the fender, and allows evaluating the stiffness of the flexible system required to achieve the desired energy absorption capacity. The design procedure accounts for the dolphin-fender interaction, as well as for the soil-embedded dolphin interaction, and it is specialised considering the common technical solutions adopted in the design of breasting dolphins. The approach is applied to a hypothetical case study consisting of a new berthing structure for a coastal terminal located on the Middle Adriatic Sea, in Italy, presenting non-ideal conditions for the installation of flexible dolphins. Applications demonstrate the effectiveness of the proposed approach and the role of the dolphin-fender interaction in withstanding the berthing actions, making it possible to design a flexible berthing structure also in the case of relatively shallow water depths.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261976 Collegamento a IRIS

2019
Effects of uncertainties of soil and pile mechanical properties on the dynamic stiffness of deep foundations in homogenous deposits
Eccomas Proceedia COMPDYN (2019) 4157-4165
Autore/i: Minnucci, Lucia; Dezi, Francesca; Carbonari, Sandro; Morici, Michele; Gara, Fabrizio; Leoni, Graziano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the soil-structure interaction framework, among the results of the soil-foundation system analysis (kinematic analysis) the dynamic impedance functions represent the force-displacement relationships of the compliant restraint for the superstructure. The intrinsic varia-bility of soil parameters and of design materials represents an uncertainty source which is nec-essary to include in the definition of the soil-foundation model, in order to predict the super-structure response adequately. The aim of this work is to evaluate effects of uncertainties on soil dynamic and mechanical properties on the impedance matrix of single piles in homogeneous soils, focusing on the sensitivity of the parameters. A Quasi Monte Carlo (QMC) simulation with sampling based on Sobol’ sequence is performed starting from the probabilistic distribu-tion of three main parameters characterizing the soil-piles response, i.e. the soil density, the shear waves velocity and the concrete elastic modulus of piles, available from the literature. The analyses are carried out through the numerical model developed by the Authors and a sen-sitivity study on the optimal number of simulations is performed, comparing the use of Quasi-random sampling with the classical Monte Carlo simulation technique. Moreover, results of sensitivity studies show the influence of variability of each considered mechanical parameter on the global response of the soil-foundation system.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267575 Collegamento a IRIS

2019
An Overview of the Structural Safety-Oriented Research in the Region Marche Seismic Area
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Capozucca, R.; Carbonari, S.; Clementi, F.; Cocchi, G.; Davi, F.; Dezi, L.; Gara, F.; Lancioni, G.; Lenci, S.; Mentrasti, L.; Ragni, L.; Serpilli, M.
Editore: Springer, Cham
Classificazione: 2 Contributo in Volume
Abstract: In recent years, Italy has been hit by earthquakes, causing significant damage to masonry and reinforced concrete (RC) structures. Especially, common buildings and ordinary structures in many small historical towns of Italian central regions, such as Marche, have suffered dramatic consequences and destruction. Dynamic analysis and seismic structural safety are important topics in civil engineering, which have been studied and deepened for many years by the researchers of the Structural Division of the Department of Civil and Building Engineering, and Architecture of UnivPM. The researches have been oriented towards the investigation of structures under seismic loads in order to improve the knowledge of the structural response under high actions, due to the soil dynamic movements and, thus, define adequate techniques to strengthen the damaged structures. In this paper we present a wide spectrum of main results of our research group, comprising experimental studies, vulnerability analysis and assessment of existing structures, new methods of modelling and theoretical approaches to define the dynamic behavior of structures, also in presence of damage. Finally, we show and discuss new prospects of research for safety, employing advanced techniques and materials to prevent collapse and/or relevant damages in structures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/281739 Collegamento a IRIS

2019
Evidence of coupled soil-structure interaction and site response in continuous viaducts from ambient vibration tests
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: Gara, Fabrizio; Regni, Marco; Roia, Davide; Carbonari, Sandro; Dezi, Francesca
Classificazione: 1 Contributo su Rivista
Abstract: The scope of this research was to identify the significance of soil-structure interaction and site response on the dynamic behaviour of continuous multispan reinforced concrete viaducts, based on ambient vibration measurements and numerical simulations, using finite element models. For this purpose, an 875 m long bridge, located in Central Italy, founded on piles in eluvial-colluvial soil deposit was instrumented and ambient vibration tests together with geophysical investigations were performed. Experimental modal properties were evaluated by means of the operational modal analysis on accelerometric data and the role of soil-structure interaction in the interpretation of tests was detected by means of finite element models characterised by different accuracy in addressing the interaction problem. In the soil-structure interaction models the local site condition in correspondence of each bridge piers (resulting from geotechnical and geophysical investigations) were taken into account in the definition of the soil-foundation impedances. Comparison between the experimental results obtained from ambient noise measurements on the free-field and on the bridge deck permits the identification of both the predominant period of the site and the fundamental periods of the structure. In addition, comparisons between results obtained from the different numerical models with the measured dynamic response of the viaduct, in terms of fundamental frequencies and mode shapes, allow the identification of the contribution of different soil-structure interaction aspects such as the pile-soil-pile interaction, the radiation problem, the pile cap embedment as well as the variability of the soil stratigraphy along the longitudinal direction of the viaduct.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264148 Collegamento a IRIS

2019
Dynamic performance of a full-scale micropile group: Relevance of nonlinear behaviour of the soil adjacent to micropiles
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: Capatti, M. C.; Dezi, F.; Carbonari, S.; Gara, F.
Classificazione: 1 Contributo su Rivista
Abstract: An extensive experimental in-situ campaign of dynamic tests carried out on a full-scale 2 x 2 group of inclined injected micropiles in alluvial soils is described in this paper. The campaign includes ambient vibration and impact load tests to investigate the dynamic behaviour of the soil-micropile system in the small strain range, and forced vibration tests to investigate the performance of the system in the nonlinear field. Accelerometers and geophones are adopted to acquire the dynamic response on the cap and the soil nerby the cap, while strain gauges are installed along the shaft of one micropile to capture the local curvatures and deflections. The influence of the micropile inclination on the translational and rotational behaviour of the group is evaluated. Moreover, the evolution of degradation phenomena such as the gap opening and slippage at the soil-micropile interface and the radial cracking of soil surrounding micropiles, are recognized, critically commenting the relevant effects on the fundamental frequencies and damping ratios of the system.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/270855 Collegamento a IRIS

2019
The Role of Soil-Structure Interaction in the Interpretation of Dynamic Tests on the “Chiaravalle viaduct”
Eccomas Proceedia COMPDYN (2019)
Autore/i: Carbonari, Sandro; Dezi, Francesca; Gara, Fabrizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper addresses the significance of soil-structure interaction on the dynamic behaviour of the “Chiaravalle viaduct”, based on ambient vibration measurements and numerical simula-tions. The viaduct is located in Central Italy and is founded on piles in an eluvial-colluvial soil deposit. Experimental modal properties are evaluated by means of the operational modal anal-ysis on accelerometric data from ambient excitation and the role of soil-structure interaction in the interpretation of tests is investigated by means of a refined finite element model of the via-duct. In the soil-structure interaction models the local site condition in correspondence of each bridge piers (resulting from geotechnical and geophysical investigations) are considered in the definition of the soil-foundations compliance. Comparison between the experimental and nu-merical results highlight the role of the pile-soil-pile interaction, the radiation problem, the pile cap embedment and the variability of the soil stratigraphy along the longitudinal direction of the viaduct in the interpretation of the experimental data.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267577 Collegamento a IRIS

2019
Modal properties variation and collapse assessment of masonry arch bridges under scour action
ENGINEERING STRUCTURES
Autore/i: Scozzese, F.; Ragni, L.; Tubaldi, E.; Gara, F.
Classificazione: 1 Contributo su Rivista
Abstract: This paper investigates the problem of flood-induced scour on masonry arch bridges through the analysis of a real case study, Rubbianello Bridge. This is a multi-span masonry arch bridge located in Central Italy, which suffered the collapse of two of the seven spans due to foundation scour during a severe flood in December 2013. The study has a twofold aim: to evaluate with a numerical model the level of scour which led to the bridge failure in 2013 and the corresponding collapse mechanism, and to assess the sensitivity of the bridge’s modal properties (vibration frequencies and mode shapes) to different levels of scour. An accurate nonlinear three-dimensional model of the bridge is developed, whose elastic properties are calibrated to match the results of dynamic identification tests performed via Operational Modal Analysis (OMA) on the remaining portion of the bridge. A numerical simulation of the effects of the scour hole progression is also performed on the full bridge, according to recently proposed techniques. The study results provide useful insights on both the cause of collapse of the bridge and the suitability of OMA for bridge scour monitoring.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/270806 Collegamento a IRIS

2018
Dynamic Test for the Model Calibration and Pier Damage Detection of an Existing R.C. Multispan Viaduct
The 2018 World Congress on Advances in Civil, Environmental and Materials Research (ACEM18) & The 2018 Structures Congress (Structures18)
Autore/i: Gara, F.; Carbonari, S.; Minnucci, L.; Regni, M.; Speranza, E.
Editore: Chan-Koon Choi
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents and discusses results of the dynamic tests performed on the Moscosi Bridge in Cingoli (Italy). The main scope of the tests is to evaluate the dynamic parameters of the bridge, such as the eigenfrequencies, the mode shapes and the relevant modal damping ratios, in order to characterize the structural behaviour before the execution of some required restoration works, providing (i) useful information for the development of the numerical model for the design and (ii) a benchmark for the evaluation of the retrofit effectiveness, by repeating tests after the retrofit. The dynamic characterization is obtained through the measurements of ambient vibrations, which are processed with the Covariance-driven Stochastic Subspace Identification. In addition, the dynamic response of the bridge subjected to a vehicle passages is registered and compared to that induced by the ambient excitations. First considerations seem to reveal the presence of the observed structural damage at the base of one pier.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259689 Collegamento a IRIS

2018
Dynamic Test Based Model Calibration of an Existing R.C. School Building
The 2018 World Congress on Advances in Civil, Environmental and Materials Research (ACEM18) & The 2018 Structures Congress (Structures18)
Autore/i: Speranza, E.; Gara, F.; Carbonari, S.; Balducci, A.; Dezi, L.
Editore: Chang-Koon Choi
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper deals with the dynamic tests carried out on a school building seismically retrofitted with an innovative system that uses external steel dissipative towers. Before the retrofitting, ambient vibration tests were carried out with the aim of evaluating the modal parameters of the building including the contribution of nonstructural components to the global dynamic behavior of the structure. In particular, the contribution of non-structural components plays fundamental role in structural design because neglecting the infills in finite element models can produce macroscopic errors that may compromise the capacity of the models to predict the structural response of the structure when used for design purposes, such as for seismic retrofitting projects. In this context, the calibration of the finite element models (f.e. models) through experimental measurements plays a fundamental role in ensuring that the models reproduce with sufficient reliability the real behavior of the structure. After the building retrofitting, ambient vibration measurements were repeated to verify that variations in modal properties of the building, evaluated at very small input energy level, are in accordance with those expected from the numerical model. Furthermore, snap-back tests of the building were performed at different load levels to assess the dissipative capacity of the new structural system at greater input energy level.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259688 Collegamento a IRIS

2018
First processing and remarks on the observed damage to the churches of the Marche Region after the centre Italy earthquake 2016
Proceedings of the 8th International Conference on Building Resilience – ICBR Lisbon’2018 Risk and Resilience in Practice: Vulnerabilities, Displaced People, Local Communities and Heritages
Autore/i: Carbonari, Sandro; Dall’Asta, Andrea; Dezi, Luigino; Gara, Fabrizio; Leoni, Graziano; Morici, Michele; Prota, Andrea; Zona, Alessandro
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The seismic sequence that struck Central Italy in August-October 2016 seriously damaged many historical buildings of the Italian cultural heritage. In particular, churches were widely damaged due to intrinsic peculiarities of their structural systems, not able to develop an efficient box-like resisting mechanism. During seismic emergency, teams of experts carried out a massive survey of churches to assess both the occurred damage and their usability. Teams have been coordinated by the Department of Civil Protection and the Ministry of Cultural Heritage and Tourism. In this paper, a methodology for processing data recorded during inspections of churches of the Marche Region is proposed and used to analyse a limited dataset. Starting from the subdivision of the sample into homogeneous typologies, the most recurring damage mechanisms are identified. In addition, the global damage indexes of each churches are correlated with the relevant highest spectral pseudo acceleration at T=0.30s registered at the site as a consequence of the main shocks; this allows obtaining relationships between the seismic intensity and the expected damage. Finally, the overall damage occurred to churches of the sample is compared to that estimated through empirical models available in the literature.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263175 Collegamento a IRIS

2018
Seismic behaviour of steel-concrete composite bridge decks
Steel and Steel-concrete composite structures in seismic areas: advances in research and design. The Research Project RP3 of the ReLUIS-DPC 2014-2018 – Activity carried out during years 2014-2016
Autore/i: Dezi, L.; Carbonari, S.; Dall’Asta, A.; Gara, F.; Minnucci, L.
Editore: Doppiavoce
Luogo di pubblicazione: Napoli
Classificazione: 2 Contributo in Volume
Abstract: The paper focuses on local problems relevant to the seismic response of steel-concrete composite bridge decks. In particular, the local mechanisms involved in the transferring of inertial forces from the slab to substructures are investigated with particular focus on the shear connection and the role of end cross beams. Firstly, open issues relevant to the seismic design and analysis of steel-concrete composite bridge decks are discussed and an overall state-of-art of the problem is depicted. Then, some case studies constituted by single span and two-spans I-shaped twin-girders and box girders steel-concrete composite bridges are selected and adopted to investigate local response of the decks subjected to seismic actions. Linear and non-linear applications are performed adopting different analysis methodologies in order to investigate stress resultants in the shear connection and to analyse the role of the end cross beams on the local transferring mechanisms of inertia forces; results of analyses on the selected case studies are shown and discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259405 Collegamento a IRIS

2018
Effect of Environmental Conditions on the Modal Response of a 10-Story Reinforced Concrete Tower
SHOCK AND VIBRATION
Autore/i: REGNI, MARCO; AREZZO, DAVIDE; Carbonari, S.; Gara, F.; Zonta, D.
Classificazione: 1 Contributo su Rivista
Abstract: We analyse the effect of temperature and wind velocity on the natural frequencies and modal damping ratios of the Faculty of Engineering Tower at the Universit`a Politecnica delle Marche, a 10-story reinforced concrete frame building, permanently monitored with low-noise accelerometers. The data recorded over the first 5 months of monitoring demonstrate that temperature variations and wind intensity have a clear effect on the first three natural frequencies and the corresponding damping ratios. Temperature is positively correlated to the first and second frequencies, corresponding to shear displacement modes and negatively correlated to the third frequency, corresponding to a torsional mode. All frequencies are positively correlated to wind velocity and changes in damping ratios are inversely correlated to any change in frequency. A mechanical explanation of these phenomena is offered, based on a critical review of literature case studies. These results suggest that using changes in modal parameters for damage detection always requires accurate knowledge of the correlation between modal parameters and environmental quantities (temperature, humidity, and wind velocity), an information which is only available through long-term continuous monitoring of the structural response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259024 Collegamento a IRIS

2018
Effects of environmental conditions on the dynamic properties of a 10-storey r.c. square tower
EESMS 2018 - Environmental, Energy, and Structural Monitoring Systems, Proceedings
Autore/i: Arezzo, Davide; Regni, Marco; Carbonari, Sandro; Gara, Fabrizio
Editore: Institute of Electrical and Electronics Engineers Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259402 Collegamento a IRIS

2018
Stochastic seismic analysis and comparison of alternative external dissipative systems
SHOCK AND VIBRATION
Autore/i: GIOIELLA, LAURA; Tubaldi, Enrico; GARA, Fabrizio; DEZI, Luigino; Dall’Asta, Andrea
Classificazione: 1 Contributo su Rivista
Abstract: This paper deals with the seismic retrofit of existing frames by means of external passive dissipative systems. Available in different configurations, these systems allow high flexibility in controlling the structural behaviour and are characterized by some feasibility advantages with respect to dissipative devices installed within existing frames. In particular, this study analyzes and compares the performances of two external solutions using linear viscous dampers. The first is based on the coupling of the building with an external fixed-based steel braced frame by means of dampers placed horizontally at the floor levels. The second is an innovative one, based on coupling the building with a “dissipative tower,” which is a steel braced frame hinged at the foundation level, and activating the dampers through its rockingmotion.Theeffectiveness of the two solutions is evaluated and compared by considering a benchmark existing reinforced concrete building,employing a stochastic dynamic approach, under the assumption of linear elastic behaviour for the seismic performance evaluation. This allows efficiently estimating the statistics of many response parameters of interest for the performance assessment and thus carrying out extensive parametric analyses for different properties of the external systems. The study results provide useful information regarding the design and the relative efficiency of the proposed retrofit solutions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/252577 Collegamento a IRIS

2018
Soil-foundation compliance evidence of the “Chiaravalle viaduct”
Lecture Notes in Civil Engineering, 2018
Autore/i: Regni, Marco; Gara, Fabrizio; Francesca, Dezi; Davide, Roia; Carbonari, Sandro
Editore: Springer
Classificazione: 2 Contributo in Volume
Abstract: This paper describes some notable aspects demonstrating the contribution of the soil-foundation compliance on the measured dynamic response of the Chiaravalle viaduct subjected to ambient excitations. The viaduct, linking the SS76 with the airport of Ancona (in Central Italy), is 875 m long and consists of four r.c. kinematic chains separated by joints. The deck is constituted by three beams supported by column bent piers constituted by two circular r.c. columns founded on a continuous footing on six concrete piles. Ambient vibration measurements have been performed to determine experimental natural frequencies and mode shapes of the viaduct before a scheduled seismic rehabilitation of the structure; data have been used to calibrate a numerical model for the retrofit design. Experimental modal properties are evaluated by means of Operational Modal Analysis; due to the great length of the viaduct, different configurations of sensors placed on the deck are used to evaluate the overall behavior of the viaduct and the Pre Global Estimation Re-scaling method is adopted in order to merge the different parts of mode shapes relevant to each configuration. Furthermore, with reference to the transverse behaviour, some tests are performed in correspondence of one pier, measuring accelerations of the foundation cap (both translational and rotational components) and the pier bent, in order to identify contribution to the transverse modal displacement due to the elastic deflection of the pier and the foundation rocking. Results of dynamic tests are interpreted through a 3D Finite Element model of the viaduct. Firstly, a conventional fixed base model is considered, then a model including the Soil-Structure Interaction problem is developed in order to improve consistency between numerical and experimental results. The numerical model including Soil-Structure Interaction is able to capture the foundation rocking, experimentally detected, and provides modal parameters in good agreement with the experimental ones.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251324 Collegamento a IRIS

2018
Full scale experimental assessment of the dynamic horizontal behavior of micropiles in alluvial silty soils
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: Capatti, M. C.; Dezi, F.; Carbonari, S.; Gara, F.
Classificazione: 1 Contributo su Rivista
Abstract: The paper deals with an extensive experimental campaign of dynamic tests performed on full-scale vertical injected and not injected micropiles embedded in alluvial soils. The experimentation includes ambient vibration and impact load tests to investigate the dynamic behaviour of the soil-micropile system in very small and small-medium strain ranges, as well as snap back tests to investigate the evolution of the post-elastic response of the system. Micropiles are instrumented with strain gauges along the shaft, accelerometers and displacement transducers at the head. Modalities and results of the different performed tests are presented, focusing on the role of high pressure injections on the dynamic behaviour of the system, on the development of non-linear soil-pile phenomena, and, finally, on the evaluation of effectiveness of the different testing procedures to capture the dynamic response of soil-micropile systems. Ambient vibration test revealed to be a versatile method to identify the dynamic properties of soil-micropile systems, although it requires demanding post-processing techniques of data. Impact load test is faster to perform and easier to post process. Free vibration test proved to be relatively simple to perform and able to catch the dynamic non-linear behaviour of soil-micropile systems.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258773 Collegamento a IRIS

2018
Shear connection local problems in the seismic design of steel-concrete composite decks
Lecture Notes in Civil Engineering
Autore/i: CARBONARI, SANDRO; GARA, Fabrizio; Dall’Asta, A.; DEZI, LUIGINO
Editore: Springer, Cham
Classificazione: 2 Contributo in Volume
Abstract: This paper investigates local problems involved in the transfer mechanisms of inertia forces acting at the level of the concrete slab of typical steel-concrete composite bridge decks. In detail, the behaviour of the shear connection, usually designed with only refer-ence to non-seismic loads at the ultimate limit state, is studied considering shear forces descending from both horizontal and trans-verse seismic actions. Some results concerning twin-girder steel-concrete composite bridge decks characterised by different static schemes are presented and the distribution of longitudinal and transverse forces acting on the shear connection is discussed. First results demonstrate the significance of properly considering seismic induced forces in the design of the steel-concrete shear connec-tion and support the need of further investigations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240818 Collegamento a IRIS

2018
Experimental modal properties of a steel arch bridge during the static load test
Lecture Notes in Civil Engineering, 2018
Autore/i: Gara, Fabrizio; Nicoletti, Vanni; Roia, Davide; Dall'Asta, Andrea
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Base isolated steel arch bridges are very complex engineering systems whose behaviour may depend not only on an accurate design but also on its correct realization during all construction phases. One of the most effective method, fast and cheap, to check the global behaviour of the structure and the correctness of the design structural models is based on the comparison between modal parameters, in terms of frequencies and mode shapes, experimentally identified by means vibration measurements with those theoretically predicted by the structural models. This paper describes the dynamic test carried out during the standard static load test of a half-through steel arch bridge. The bridge is built over the Potenza river, in central Italy, and its structural design is characterized by some notable aspects: the river crossing is obtained by two coupled steel arches, having a span length around 115 m, and a steel-concrete composite deck sustained by thirty couples of steel hangers; the arches are supported on rubber bearing seismic isolators. An accelerometer array was installed over the bridge deck to study the evolution of the modal parameters of the structure at specific phases of the load test: first on the unloaded configuration, then on two different loaded configurations, made by placing trucks over the deck, and finally after the bridge unloading. Measurements of ambient vibrations were carried out and Operational Modal Analysis was performed to estimate modal properties of the deck. Experimental values of the resonance frequencies and related mode shapes are compared with those obtained with the predictive finite element model developed for design purposes and opportunely modified to account for the real conditions of the bridge during the tests. In particular, the dynamic interaction between bridge and trucks was investigated by considering trucks not only in terms of added mass but as dynamic systems characterized by mass, stiffness and damping properties. The obtained results show the effects of the trucks on the dynamic parameters of the bridge and allow the reliability assessment of the numerical model.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251330 Collegamento a IRIS

2018
Dynamic in situ tests for the calibration of an infilled R.C. Building F.E. model
EESMS 2018 - Environmental, Energy, and Structural Monitoring Systems, Proceedings
Autore/i: Nicoletti, Vanni; Gara, Fabrizio; Regni, Marco; Carbonari, Sandro; Dezi, Luigino
Editore: Institute of Electrical and Electronics Engineers Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259399 Collegamento a IRIS

2018
A low cost wireless sensor node for building monitoring
EESMS 2018 - Environmental, Energy, and Structural Monitoring Systems, Proceedings
Autore/i: Valenti, S.; Conti, M.; Pierleoni, P.; Zappelli, L.; Belli, A.; Gara, F.; Carbonari, S.; Regni, M.
Editore: Institute of Electrical and Electronics Engineers Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259400 Collegamento a IRIS

2018
Fatigue assessment of continuous composite bridges accounting for slab casting sequences
STRUCTURAL ENGINEERING INTERNATIONAL
Autore/i: GARA, Fabrizio; Formica, Massimo; Leoni, Graziano; DEZI, Luigino
Classificazione: 1 Contributo su Rivista
Abstract: The paper presents a procedure for the fatigue assessment of continuous steel– concrete composite bridges which accounts for concrete slab casting sequences. Cracking, tension stiffening, creep and shrinkage (thermal, endogenous and drying) effects are included in the analysis in order to correctly evaluate the stress state of steel girders. The purpose of the paper is to present a method that, based on the analysis of a number of models developed according to the structure’s evolution, leads to a more effective and realistic fatigue assessment than that usually performed in practice. The method proposed is applied to a case study of a continuous, twin-girder, composite bridge deck, showing the influence of three different slab casting modalities on fatigue assessment.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261719 Collegamento a IRIS

2018
Modal properties and seismic behaviour of buildings equipped with external dissipative pinned rocking braced frames
ENGINEERING STRUCTURES
Autore/i: Gioiella, L.; Tubaldi, E.; Gara, F.; Dezi, L.; Dall’Asta, A.
Classificazione: 1 Contributo su Rivista
Abstract: This paper deals with the seismic protection of building frames by means of external dissipative systems. Dampers and external framing system can be arranged in several configurations, involving different kinematic behaviours and seismic performances. This study analyses a recently-developed solution called “dissipative tower”, which exploits the rocking motion of a steel braced frame, hinged at the foundation level, for activating the dampers. This system aims at controlling both the global response and the local storey deformation of the frame, by using a reduced number of viscous dampers. A state space formulation of the dynamic problem is presented in general terms, together with the solution of the seismic problem via the modal decomposition method. A parametric study is carried out to evaluate the influence of the added damping and of the braced frame stiffness on the modal properties and seismic response of a benchmark reinforced concrete frame retrofitted with the external dissipative towers. It is shown that the addition of the towers yields a regularization and reduction of the drift demand along the building height, but it may induce significant changes, not always beneficial, in the distribution of internal actions of the frame and in the absolute storey accelerations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259025 Collegamento a IRIS

2017
Risposta sismica non lineare di pile da ponte fondate su gruppi di pali inclinati
Atti del 17° Convegno Nazionale – L’ingegneria sismica in Italia (ANIDIS 2017)
Autore/i: Michele, Morici; Sandro, Carbonari; Fabrizio, Gara; Francesca, Dezi; Graziano, Leoni
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Questo lavoro presenta i primi risultati di una ricerca orientata allo studio degli effetti della configurazione e dell’inclinazione dei pali sulla risposta sismica non lineare di pile da ponte. La metodologia di analisi, basata su un approccio alle sottostrutture, viene preventivamente presentata; il sistema terreno-fondazione è analizzato nel dominio delle frequenze adottando un modello numerico sviluppato dagli autori mentre l’analisi di interazione inerziale delle sovrastrutture è svolta nel dominio del tempo per coglierne il comportamento non lineare. La dipendenza dalla frequenza delle funzioni di impedenza del sistema terreno-fondazione è approssimata nel dominio del tempo, attraverso un opportuno modello a parametri concentrati. La procedura è applicata ad alcuni casi studio costituiti da pile da ponte singole fondate in depositi di terreno argilloso di modesta ed elevata rigidezza. Sono considerate fondazioni costituite da pali aventi diversa inclinazione e pile caratterizzate da diversi periodi fondamentali e momenti flettenti di snervamento delle sezioni trasversali di base, al fine di simulare sistemi con diverso comportamento elastoplastico. I risultati delle analisi evidenziano il ruolo chiave rivestito dal rocking di fondazione sulla risposta strutturale e dimostrano che le fondazioni con pali inclinati possono contribuire a ridurre gli spostamenti massimi della testa della pila e la domanda di duttilità.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251351 Collegamento a IRIS

2017
Prime Rielaborazioni Circa i Danni Rilevati alle Chiese delle Marche a Seguito del Terremoto del Centro Italia (2016)
Gruppo Nazionale di Geofisica della Terra Solida - 36° convegno nazionale - Trieste, 14-16 novembre 2017
Autore/i: Carbonari, S.; Dall’Asta, A.; Dezi, L.; Gara, F.; Leoni, G.; Morici, M.; Prota, A.; Zona, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Le chiese sono edifici con valore storico e artistico che presentano una diffusione capillare nel territorio dell’Italia centrale e costituiscono una componente importante del patrimonio culturale. Il corpo di fabbrica di una chiesa è costituito da sottosistemi strutturali ricorrenti quali la facciata, le pareti laterali, il transetto, l’abside, la navata centrale e laterali, che tendono ad esibire risposte sismiche spesso indipendenti Studi effettuati sui danni subiti dalle chiese a seguito degli eventi sismici del Friuli 1976 (Doglioni et al. 1994), di Umbria-Marche 1997 (Lagomarsino e Podestà 2004a,b), del Molise 2002 (Lagomarsino e Podestà 2004c) dell’Aquila 2009 (Lagomarsino 2012) e dell’Emilia 2012 (Indirli et al. 2012, Sorrentino et al. 2014) hanno mostrato come i meccanismi di danno presentino caratteristiche ricorrenti nonostante l’unicità di ogni corpo di fabbrica. Partendo dalle conoscenze maturate nei precedenti studi eseguiti a seguito di eventi sismici importanti, in questo lavoro gli autori hanno rielaborato i primi dati relativi al danneggiamento subito dal patrimonio culturale marchigiano con l’obiettivo finale di individuare le relazioni che intercorrono tra danno osservato e intensità di scuotimento..Lo studio, di carattere metodologico, prende in esame un sottoinsieme dei dai dati raccolti nella visita di circa 3600 chiese e intende principalmente mettere in evidenza i problemi connessi all'elaborazione di informazioni spesso non omogenee, proponendo alcune strategie per la loro interpretazione.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258369 Collegamento a IRIS

2017
An innovative seismic protection system for existing buildings: external dissipative towers
Proceedings of the 16th World Conf. on Earthquake Engineering, WCEE 2017
Autore/i: Gioiella, L.; Balducci, A.; Carbonari, S.; Gara, F.; Dezi, L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: A common technique for the retrofit of existing structure is based on the installation of dissipative devices connecting adjacent storeys of buildings in either diagonal or chevron brace configurations. This type of damping system may present some disadvantages like the increment of axial forces in columns, which may leads to premature local failures, or some feasibility limits on the strengthening of the existing foundations at the base of the bracing system. In addition, indirect costs related to the interruption of the building utilization during execution of the retrofit can be very demanding, in particular for strategic buildings, such as hospitals or schools. Most of previous problems can be overcome by placing the dissipative bracings and the relevant foundations outside the building; systems with external dampers can be grouped into three main categories, depending on the kinematic behaviour of the system, which is a function of the arrangement of dampers and bracings. Recently, some applications have been developed by proposing a new configuration exploiting the rocking motion of a stiff external tower. This paper deals with this innovative system for seismic protection of existing buildings, especially strategic ones, patented as “Dissipative Towers”. The protection system is based on the structural coupling of the building with new steel truss towers constructed externally and then rigidly connected to the building floors by means of steel elements; the towers are erected over a rigid r.c. thick base plate that is restrained to the foundation cap with a spherical hinge located in central position of the base slab. The towers are equipped with dissipative devices connecting the corners of the two plates; the effectiveness of the dampers is enhanced by the use of articulated quadrangles which amplify the vertical displacements of the devices. The efficiency of the system is so high that usually it is designed to satisfy the immediate occupancy limit state even for high intensity earthquakes. The above system is applied to the retrofit of an existing school building in Italy, constituted by different blocks made of reinforced concrete frames. The seismic rehabilitation is obtained by suitably positioning external dissipative towers and eliminating expansion joints between adjacent blocks. The towers allow a high level of seismic protection at the ultimate limit state, with a significant reduction of horizontal displacements and accelerations. Moreover also the shear actions resisted by the existing frame are significantly reduced by the "Dissipative Towers". The seismic protection is achieved with a moderate economic impact due to the elimination of indirect costs related to the arrangement of internal spaces, interruption and/or relocation of activities.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247090 Collegamento a IRIS

2017
The Role of End Cross-beams on the Distribution of Seismic Induced Shear Actions on the Shear Connection in Steel-Concrete Composite Bridge Decks
Atti delle XXVI Giornate Italiane della Costruzione in Acciaio
Autore/i: Sandro, Carbonari; Lucia, Minnucci; Fabrizio, Gara; Luigino, Dezi; Andrea, Dall'Asta
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper focuses on local problems arising in the shear connection of typical steel-concrete com-posite bridge decks subjected to seismic actions. In detail, a case study constituted by an I-shaped twin-girder simply supported steel concrete composite deck is considered and the distribution of forces on the shear connection along the beams is presented, focusing on the role of end cross-beams. After a brief survey of the results obtained in previous researches by the authors, aimed at justifying the adopted analysis methodology, results of static equivalent seismic analyses of the se-lected case studies are shown and discussed, considering end cross-beams of different typology and stiffness. Results demonstrate the key role played by end cross-beams on the distribution of seismic actions on the shear connection.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251353 Collegamento a IRIS

2017
Validazione di un modello 3D per l’interazione dinamica terreno-struttura mediante prove in sito su fondazioni profonde
Atti del 17° Convegno Nazionale – L’ingegneria sismica in Italia (ANIDIS 2017)
Autore/i: Maria Chiara Capatti, ; Sandro, Carbonari; Francesca, Dezi; Fabrizio, Gara; Graziano, Leoni; Michele, Morici
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In questo articolo viene presentata e discussa la duplice validazione di un modello numerico per l’interazione dinamica terreno-fondazione-struttura nel caso di fondazioni profonde. Il modello, originariamente sviluppato per gruppi di pali verticali in terreni stratificati, e recentemente aggiornato per tener conto dell’inclinazione dei pali, considera l’interazione terreno-palificata e lo smorzamento per radiazione attraverso funzioni elastodinamiche di Green. La validazione è basata su dati sperimentali ottenuti attraverso due distinte campagne sperimentali. La prima campagna prove riguarda tre pali in acciaio vibro-infissi in ambiente marino, sui quali sono state eseguite prove di impatto e prove di snap-back, misurando le deformazioni lungo il palo sorgente e le accelerazioni in testa al palo sorgente e a quelli riceventi. Il secondo gruppo di dati sperimentali è stato ottenuto durante una recente campagna prove su due micropali singoli verticali e su un gruppo di tre micropali inclinati in terreno limoso alluvionale, durante la quale sono state eseguite prove di vibrazioni ambientali e di impatto, prove di snap-back e prove in condizioni di vibrazioni forzate. Attraverso il confronto tra dati numerici e sperimentali in termini di impedenza del sistema, si discute la capacità previsionale del modello nel simulare il fenomeno dell’interazione palo terreno al variare della tipologia di fondazione profonda.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251352 Collegamento a IRIS

2017
Prime analisi e considerazioni circa i danni rilevati al patrimonio culturale delle Marche a valle del terremoto del Centroitalia (2016)
Atti del 17° Convegno Nazionale – L’ingegneria sismica in Italia (ANIDIS 2017)
Autore/i: Sandro, Carbonari; Alessandro, Catanzaro; Valerio, D’Agostino; Andrea, Dall’Asta; Luigino, Dezi; Fabrizio, Gara; Graziano, Leoni; Michele, Morici; Andrea, Prota; Alessandro, Zona
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: La sequenza sismica che ha interessato l’Italia centrale a partire dal 24 Agosto 2016 ha provocato danni anche di grave entità a molti edifici di importanza storica e artistica. In particolare, per le peculiarità degli impianti strutturali incapaci di sviluppare un meccanismo resistente scatolare, le chiese sono state la tipologia di edifici storici maggiormente colpita. A seguito dell’emergenza sismica, squadre composte da tecnici esperti hanno eseguito sopralluoghi sulle chiese segnalate con il fine di valutare sia l’entità del danno che lo stato di sicurezza. Le squadre sono state coordinate dal Dipartimento di Protezione Civile (DPC) e dal Ministero dei Beni e delle Attività Culturali e del Turismo (MiBACT), tramite le strutture operanti all'interno della direzione di comando e controllo (Dicomac) e le sedi regionali del MiBACT. Nel presente lavoro, i dati registrati nelle schede A-DC compilate durante i sopralluoghi sono stati rielaborati per un campione di chiese della regione Marche. Operando sul campione si propone una metodologia di analisi che potrà in futuro applicarsi alla totalità dei dati. Partendo dalla suddivisione del campione in tipologie omogenee, sono stati analizzati i meccanismi di danno più ricorrenti. In aggiunta, gli indici di danno globali di ogni chiesa sono stati correlati con i massimi valori di Pseudo Accelerazione Spettrale a 0.30s registrati in sito in conseguenza delle maggiori scosse, nel tentativo di derivare una relazione tra intensità di scuotimento e danno atteso. Infine i danni rilevati nel campione sono stati confrontati con quelli forniti dai modelli empirici di vulnerabilità messi a punto sulla scorta dei dati registrati a seguito del terremoto Umbria-Marche 1997.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251347 Collegamento a IRIS

2017
An external bracing system for the retrofit of r.c. frame buildings: modal properties and seismic response
Proceedings of the 16th World Conf. on Earthquake Engineering, WCEE 2017
Autore/i: Gioiella, L.; Tubaldi, E.; Gara, F.; Dall’Asta, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper deals with the seismic protection of existing buildings using external viscous damper systems to increase energy dissipation capacity. Usually the addition of dissipative diagonals in existing frames has some drawbacks as increment of internal actions in the columns, need of intervention at foundation level, feasibility limits and indirect costs related to the interruption of the building utilization. These problems can be efficiently avoided by placing the dissipative bracings and the relevant foundations outside the existing building. Dampers and bracings can be arranged in very different configurations and the possible solutions can be grouped into different categories, depending on the specific kinematic behavior, but all permitting the control of both the total amount of the dissipated energy and the frame deformation at the various storeys. In this work, the formulation of the problem involving the coupling of the existing frame with an external damping system is presented in general terms and is employed to investigate both the influence of the external bracing properties on the overall dynamic properties of the coupled system (such as the mode displacement profile, the relevant internal action distribution and the modal damping ratios) and the global effect of the retrofitting on the seismic response. Presented results concern the so called "dissipative tower", a recent solution which exploits the rocking motion of a stiff steel truss hinged at the foundation level for the dampers activation. The influence of the external dissipative bracings on the most important modal properties of the system are shown and it is observed that the bracing system notably influences the stiffness and damping properties while it modifies only marginally the mass properties of the existing frame. Finally the global effect on the seismic response, in terms of both displacements and base shear, is presented by solving the dynamic problem with the modal decomposition method by also investigating the contribution of the higher modes on the dynamic response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247083 Collegamento a IRIS

2017
Assessment survey of public school buildings after August 2016 Italy earthquake: preliminary results
Proceedings of the 16th World Conference on Earthquake Engineering (16WCEE)
Autore/i: Abruzzese, D.; Bergami, A.; Biondi, S.; Camata, G.; Canciani, M.; Carbonari, S.; Cimino, A.; Dall’Asta, A.; Dezi, F.; Dezi, L.; Di Fabio, F.; Ferracuti, B.; Fiorentino, G.; Forte, A.; Fragiacomo, M.; Gara, F.; Ianniruberto, U.; Imperatore, S.; Lavorato, D.; Leoni, G.; Liberatore, D.; Liberatore, L.; Mannella, A.; Martinelli, A.; Mutignani, C.; Nuti, C.; Paolacci, F.; Pagano, E.; Rasulo, A.; Santini, S.; Sorrentino, L.; Vanzi, I.; Zucconi, M.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247082 Collegamento a IRIS

2017
Soil-structure interaction effects in single bridge piers founded on inclined pile groups
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: CARBONARI, SANDRO; Morici, Michele; Dezi, Francesca; GARA, Fabrizio; Leoni, Graziano
Classificazione: 1 Contributo su Rivista
Abstract: This paper investigates the seismic response of bridge piers founded on inclined pile groups in different soil deposits, evaluating effects of soil-structure interaction induced by different pile group geometries and piles inclinations. Analyses are performed in the frequency domain by means of the direct approach taking advantage of a numerical model developed by the authors for the analysis of inclined pile groups. Both the superstructure and piles are modelled with beam elements and the soil is schematized as a visco-elastic medium constituted by independent infinite horizontal layers. The soil-pile and the pile-soil-pile interaction are captured in the frequency domain by means of elastodynamic Green’s functions that also allow including the hysteretic and radiation damping. The significance of kinematic stress resultants in piles, the foundation filtering effect and the rotational component of the input motion due to the coupled roto-translational behaviour of the soil-foundation system are also investigated; to this purpose kinematic interaction analyses are performed. These analyses revealed essential for the understanding of the general phenomena governing the dynamic response of the whole soil-foundation-superstructure systems. Results of numerical investigations highlight that conventional design approaches suggested by codes do not provide reliable predictions of the superstructure displacements and stress resultants.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240768 Collegamento a IRIS

2017
Simple Physical Models to Simulate the Behavior of Buckling-Type Marine Fenders
JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE
Autore/i: ANTOLLONI, GIULIA; CARBONARI, SANDRO; GARA, Fabrizio; LORENZONI, CARLO; MANCINELLI, ALESSANDRO
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents a simple physical model for the numerical simulation of the behavior of buckling-type marine fenders. The proposed model is characterized by four parameters and is derived starting from similarities between the unstable behavior of marine fenders and shallow arches. In this model, the large displacements solution expressing the relationship between the model displacements and reaction force is determined in a nondimensional form, and the model parameters are calibrated to minimize residuals between real and predicted normalized reaction force–deflection curves. By considering an in-series arrangement of two elementary physical models, the approach can be also used to simulate the behavior of parallel-motion fenders. The proposed model can be directly implemented in commercial computer programs for structural analysis to study interactions arising between buckling-type marine fenders and flexible berthing structures. In this paper, the model effectiveness in capturing the behavior of fenders and parallel motions systems is evaluated through comparisons of results, both in terms of reaction force and absorbed energy, with data of real devices, obtained from three different manufacturers. Results demonstrate the model efficiency and suitability for reproducing the behavior of a wide range of devices.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/236277 Collegamento a IRIS

2017
Analysis and comparison of two different configurations of external dissipative systems
Procedia Engineering
Autore/i: Laura, Gioiella; Enrico, Tubaldi; Fabrizio, Gara; Luigino, Dezi; Andrea, Dall’Asta
Editore: Elsevier Ltd
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper deals with the seismic protection of existing buildings, especially r.c. frame ones, by means of external passive dissipative systems. These type of systems provide larger flexibility in controlling the structural behavior, and some feasibility advantages, but their efficiency in terms of performance still need to be proven. In particular, this study analyzes and compares the performance of two external solutions using linear fluid viscous dampers (FVDs) for the seismic upgrading of an existing benchmark structure, the Van Nuys building. The first arrangement is a recent solution, known as "Dissipative Tower", which exploits the rocking motion of a steel truss hinged at the foundation level for the dampers activation; the second one consists in coupling the building with an external stiff contrasting structure, where the dampers are located horizontally at the storey level. First, a state space formulation of the problem, based on the assumption of linear elastic behavior for both the existing frame and the external dissipative structures, is presented in general terms. The proposed formulation, suitable for both the external arrangements, allows to evaluate the influence of the dissipative solutions on the system modal properties. Successively, the performance of the two proposed external passive structures, is evaluated and compared with that of the bare existing frame, by considering important engineering demand parameters (EDPs) such as interstorey drifts, absolute accelerations and shear actions resisted by the frame and by external systems.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251335 Collegamento a IRIS

2017
Dynamic behaviour of a retrofitted school building subjected to the after-shock sequence of the 2016 Central Italy earthquake
Procedia Engineering
Autore/i: Gara, Fabrizio; Regni, Marco; Carbonari, Sandro; Balducci, Alessandro; Dezi, Luigino
Editore: Elsevier Ltd
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper deals with the dynamic behaviour of a 1960s school building in Camerino subjected to moderate earthquakes belonging to the after-shock sequence of the 2016 Central Italy earthquake. The school structure, constituted by RC frames, was seismically retrofitted by means of "Dissipative Towers", an innovative system based on the use of external stiff steel truss towers equipped with dissipative dampers. Modal properties of the building after the retrofit have been determined through ambient vibration tests. After the main shock of the 2016 Central Italy earthquake, the building was instrumented with low-noise accelerometers and the dynamic behaviour of the structure during several aftershocks was recorded. Firstly, a numerical finite element model of the building is developed and calibrated on the basis of the ambient vibration measurements; then the registered dynamic response of the structure for the highest aftershock event (among the registered ones) is compared with that obtained numerically with the calibrated model. Results demonstrate the good agreement of the registered and predicted response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251328 Collegamento a IRIS

2017
Linear and Nonlinear Dynamic Response of Piles in Soft Marine Clay
JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING
Autore/i: Dezi, Francesca; Gara, Fabrizio; Roia, Davide
Classificazione: 1 Contributo su Rivista
Abstract: his paper presents the results of free vibration tests carried out at different load levels on a system of three near-shore steel pipe piles vibro-driven into soft marine clay. Piles are arranged in an L-shaped horizontal layout and are free at the head. The instrumentation consists of strain gauges placed at selected levels along the shaft of the loaded pile and accelerometers at the head of the receiver piles. The aim of this experiment is to analyze the dynamic soil–water–pile and pile-to-pile interaction and to investigate the development of nonlinearities at increasing load levels. The results of experimental modal analyses, in terms of natural frequencies and damping ratios of the system, are presented and the complex dynamic behavior of the vibrating soil–water–pile system and the pile-to-pile interaction are discussed. For a better reliability assessment of the system response in the range of linear behavior, the results of free vibration tests at the lowest level of the applied loads are compared with those obtained from impact load tests.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240557 Collegamento a IRIS

2016
Experimental and numerical modal analysis of a historical masonry bridge
Proceedings of the 16th Int. Brick and Block Masonry Conference - Trends, Innovations and Challenges, IB2MAC
Autore/i: Dezi, L.; Gara, F.; Roia, D.; Leoni, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240882 Collegamento a IRIS

2016
A higher order finite element to analyse steel-concrete composite bridge decks
Proceedings of the 19th IABSE Congress
Autore/i: Carbonari, Sandro; Dezi, Luigino; Gara, Fabrizio; Leoni, Graziano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents a novel interdependent interpolation finite element for a higher order beam model capable of capturing the shear-lag phenomenon and the overall shear deformability of composite beams. After a brief overview of the beam kinematics and of the differential solving equations, the stiffness matrix and the nodal forces to be used in a standard finite element procedure are derived in a consistent way by exploiting properties of exponential matrices ad their application in the solution of linear differential equation systems. Some comparisons with solutions obtained by using finite elements with polynomial interpolating functions demonstrate the capability of the new element.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240871 Collegamento a IRIS

2016
Dynamic Characterization of Open-ended Pipe Piles in Marine Environment
Applied Studies of Coastal and Marine Environments
Autore/i: Dezi, Francesca; Gara, Fabrizio; Roia, Davide
Editore: Maged Marghany
Classificazione: 2 Contributo in Volume
Abstract: This chapter is focused on the experimental investigations that can be carried out to dynamically characterize open-ended pipe piles in marine environment. Different test typologies, such as impact load test, free vibration test, forced vibration test, and ambient vibration test, are presented and described with the purpose to provide the right tools to analyze the dynamic behavior, at both small and large strains, of single piles or a system of piles. The appropriate instrumentation, with the suitable protection from marine environment and pile driving installation procedure, is also illustrated. Furthermore, the most common signal processing techniques useful for handling the experimental raw data are addressed together with the analysis techniques for the evaluation of the modal parameters: natural frequencies, damping ratios, and mode shapes. Finally, a part of the experimental campaign carried out by the authors on near-shore open-ended pipe piles is reported as a case study.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240920 Collegamento a IRIS

2016
An innovative seismic protection system for existing buildings: External Dissipative Towers
Proceedings of the 19th Congress of IABSE, Challenges in Design and Construction of an Innovative and Sustainable Built Environment
Autore/i: Carbonari, S.; Dezi, L.; Gara, F.; Leoni, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240884 Collegamento a IRIS

2016
Dynamic structural control of the “Caffaro Viaduct” by means of vibrational measurements
Proceedings of the 2016 IEEE Workshop on Environmental, Energy and Structural Monitoring Systems (EESMS)
Autore/i: Roia, D.; Speranza, E.; Gara, F.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240881 Collegamento a IRIS

2016
Dynamic Monitoring of an Isolated Steel Arch Bridge during Static Load Test
Proceedings of the 2016 IEEE Workshop on Environmental, Energy and Structural Monitoring Systems (EESMS)
Autore/i: Gara, F.; Nicoletti, V.; Roia, D.; Dezi, L.; Dall’Asta, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240879 Collegamento a IRIS

2016
Modal Properties and Seismic Response of Existing Building Retrofitted by External Bracings with Viscous Dampers
Proceedings of ECCOMAS, European Congress on Computational Methods in Applied Sciences and Engineering
Autore/i: Gioiella, L.; Tubaldi, E.; Gara, F.; Dall’Asta, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240878 Collegamento a IRIS

2016
Experimental study on instrumented micropiles
EESMS 2016 - 2016 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems, Proceedings
Autore/i: Capatti, Maria Chiara; Carbonari, Sandro; Gara, Fabrizio; Roia, Davide; Dezi, Francesca
Editore: Institute of Electrical and Electronics Engineers Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the present work, first steps of an extensive experimental study carried out on two vertical micropiles in alluvial silty soil are presented. One of the vertical micropiles is injected throughout valves a-manchèttes placed along the steel core of the shaft, while the other one is grouted with a unique global injection. Both of them are instrumented with several strain gauges along the shaft and an accelerometer at the head. The protection technique adopted to prevent damages on the strain gauges during micropile installation and high-pressure injections is also discussed. The main objectives of this experimental campaign are the monitoring of the modifications in the dynamic characteristics of the complex soil-micropile system due to execution techniques and construction stages, and the investigation of the dynamic response considering different kind of cyclic and dynamic loading. In particular, the effect of the high-pressure injections on the dynamic response of vertical micropiles is here investigated, by means of series of ambient vibrations and lateral impact loading tests. Experimental data of impact load tests are finally compared with results obtained from an analytical model.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240910 Collegamento a IRIS

2016
Current state of the dynamic monitoring of the "chiaravalle viaduct"
EESMS 2016 - 2016 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems, Proceedings
Autore/i: Roia, Davide; Regni, Marco; Gara, Fabrizio; Carbonari, Sandro; Dezi, Francesca
Editore: Institute of Electrical and Electronics Engineers Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper describes some notable aspects regarding the dynamic monitoring planned for the Chiaravalle viaduct, linking SS76 and airport of Ancona in Falconara, in Italy. The viaduct is 875 m long and consists of four r.c. kinematic chains separated by joints. The deck is constituted by three beams supported by column bent piers constituted by two circular r.c. columns founded on a continuous footing on six concrete piles. The first purpose of the dynamic monitoring is to determine the experimental natural frequencies and mode shapes of the viaduct before a scheduled seismic rehabilitation. Then, comparison of the first results with those obtained after the retrofit of foundation and piers and finally after the substitution of the deck bearing, will contribute to evaluate efficiency of the executed works. Two different inputs are used for the dynamic tests, ambient and traffic vibrations. An Operational Modal Analysis is carried out starting from the collected data, using the Enhanced Frequency Domain Decomposition technique. Different sensor configurations are used to evaluate the overall behaviour of the viaduct. The Pre Global Estimation Re-scaling method is adopted in order to merge the different parts of mode shapes relevant to each configuration. Results of dynamic tests are interpreted through a 3D Finite Element model of the viaduct. Firstly, a conventional fixed base model is considered, then a model including the Soil-Structure Interaction phenomena is developed in order to improve consistency between numerical and experimental results. The modal parameters obtained by the model including Soil-Structure Interaction are in good agreement with those estimated experimentally.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240911 Collegamento a IRIS

2015
Impedances of inclined piles: an analytical solution
Atti del 16° Convegno Nazionale – L’ingegneria sismica in Italia (ANIDIS 2015)
Autore/i: Carbonari, Sandro; Morici, Michele; Gara, Fabrizio; Dezi, Francesca; Leoni, Graziano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper presents an analytical solution, based on the beam-on-dynamic Winkler foundation approach, for the evaluation of the dynamic impedances of inclined single piles. The Euler-Bernoulli beam model is adopted for the pile whereas analytical expressions available in literature for viscoelastic layers undergoing harmonic vibrations of a rigid disk are used for the soil. The system of partial differential equations, governing the coupled flexural and axial behaviour of the pile embedded in a homogenous soil layer, is solved analytically in terms of exponential matrices. By assuming non-homogeneous kinematic boundary conditions, the dynamic stiffness matrix of the soil-pile system is derived analytically. In the case of layered soils, the pile is discretized into segments within which soil properties are constant and the dynamic stiffness matrix of the system is obtained according to the direct stiffness approach assembling contributions of all segments. Expressions of the soil-foundation impedance functions are derived by the problem condensation. Comparisons of results with those obtained from rigorous boundary element formulations demonstrate that the model, characterised by a very low computational effort, is able to reproduce the dynamic compliance of the soil-pile system with a good level of accuracy.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/227951 Collegamento a IRIS

2015
The Rocca Roveresca of Senigallia: seismic vulnerability of the defensive walls
Accademia Nazionale dei Lincei, XXXIII giornata dell’ambiente, Resilienza delle città d’arte, Enhancing Resilience of historic cities to earthquakes
Autore/i: Dezi, Luigino; Carbonari, Sandro; Gara, Fabrizio; Dall’Asta, Andrea; Leoni, Graziano; Zona, Alessandro
Editore: Bardi Edizioni
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: With the advent of cannons in XV century, many defensive walls underwent retrofitting to improve their capac-ity to withstand shots of the new powerful weapons. New lines of walls were erected by filling the left space with rubble stone materials. The different strata are characterized by specific behaviours and by well definite discontinuity surfaces so that the assessment of seismic vulnerability of such kind of defensive walls requires the definition of tailored failure mechanisms. A study on the behavior of the walls of the Rocca Roveresca of Senigallia in Italy is presented. A linear finite element model is first developed in order to understand the dy-namic behavior of a generic portion of the wall and to detect the probable incipient failure mechanisms. A subsequent static nonlinear analysis is carried out to investigate the formation of the cracking layout and to detect the position of plastic hinges. The last analysis level is carried out by supposing the wall to behave as a set of rigid blocks constituting a kinematic chain subjected to a finite displacement field typical for the col-lapse situation by introducing the degradation of the behavior of the inner (the less consistent) stratum.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233497 Collegamento a IRIS

2015
Esempio di indagini sperimentali eseguite per il controllo e la qualificazione meccanica del calcestruzzo in opera mediante la prova di estrazione (pull-out) con l'impiego di innovativo tassello post-inserito Thoro
INGENIO
Autore/i: Gara, F.; Bufarini, S.; D’Aria, V.; Foglia, M.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240921 Collegamento a IRIS

2015
Analytical solution for a new higher order steel-concrete composite beam model
Proceedings of ICASS2015 – Eighth International Conference on “Advances in Steel Structures”
Autore/i: Gara, Fabrizio; Carbonari, Sandro; Leoni, Graziano; Dezi, Luigino
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents an analytical solution of a composite beam model in which the constrained kinematics takes account of the overall shear deformability, warping of the slab cross section and of the steel beam, and partial shear interaction between slab and girder. The warping functions are obtained by considering the problem of unrestrained thin-walled members subjected to self-equilibrated elementary load schemes. The governing equations are derived from the balance condition imposed with the Virtual Work Theorem. The analytical solution of the governing differential equations is obtained exploiting exponential matrices. This method, furnishing the exact formulation of the solution without requiring any discretization of the beam, is used to determine the solution of the proposed applications according to the stiffness method, deriving the stiffness matrix and the reactions of fixed-end beams. Two case studies, i.e. a symmetric two span bridge deck subjected to a uniformly distributed load and to a point load, are presented; the comparisons with results obtained with a refined shell finite element model are very satisfactory.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233486 Collegamento a IRIS

2015
Modal properties of existing building retrofitted by external bracings with viscous dampers
Atti del XVI Convegno ANIDIS
Autore/i: Gioiella, Laura; Gara, Fabrizio; Tubaldi, Enrico; Dall'Asta, Andrea
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper deals with the seismic protection of existing buildings using external viscous damper systems to increase energy dissipation capacity. Dampers and bracings can be arranged in very different configurations and the possible solutions can be grouped into different categories, depending on the specific kinematic behavior. In this work, the formulation of the problem involving the coupling of the existing frame with an external damping system is presented in general terms and some issues concerning the influence of the bracing properties on the dynamic response of the coupled system are investigated. Presented results concern the so called "dissipative tower", a recent solution which exploits the rocking motion of a stiff steel truss hinged at the foundation level for the dampers activation; the influence of the external dissipative bracings on the most important modal properties of the system, such as the mode displacement profile, relevant internal action distribution and relations between damper dimensions and effective modal damping are shown. Finally the global effect on the seismic response, in terms of displacements and base shear, is presented by solving the dynamic problem with the modal decomposition method in order to investigate the contribution of the higher modes on the dynamic response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233584 Collegamento a IRIS

2015
Influence of connections modeling on the seismic behaviour of industrial buildings
Proceedings of COMPDYN 2015
Autore/i: Tassotti, Luca; Radi, Mohammed; Gara, Fabrizio; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Many industrial buildings with a precast concrete structure have been designed in accordance with non-seismic provisions by considering only gravity loads or, in some other cases, in accordance with not adequate seismic detailing requirements .In particular, seismic events that occurred in the recent past have shown that the connections between the main structural elements play an important role on the dynamic and seismic behaviour of the pre-cast concrete structure. Nowadays, the more advanced technical standards require mechani-cal connections between the precast elements; however codes do not furnish exhaustive information about the design and modelling of these connections neither in the seismic vul-nerability assessment of existing buildings nor in the design of new constructions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233472 Collegamento a IRIS

2015
Operational Modal Analysis on r.c. building for the evaluation of the dynamic changes due to retrofitting
Proceedings of EESMS 2015, Environmental, Energy and Structural Monitoring Systems
Autore/i: Roia, Davide; Gara, Fabrizio; Speranza, Elisa; Gioiella, Laura; Dezi, Luigino
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper deals with the changes of the modal parameters of a r.c frame building sited in Camerino, Italy. Operational modal analysis were performed before and after the seismic retrofitting of the building achieved with an innovative system that uses external steel towers equipped with dissipative devices. Before retrofitting, ambient vibration tests were carried out with the aim of evaluating the actual linear dynamic behavior of the building including the contribution of non-structural components (e.g. external and internal walls); modal parameters, i.e. natural frequencies and mode shapes determined by means of experimental modal analysis, allowed the calibration of a predictive f.e. model of the building which was crucial for the final design of the retrofitting system. Tests were repeated after the retrofitting works, with the main objective to verify that changes of modal parameters are in agreement with those predicted by the f.e. model. Results and comparisons between the modal parameters obtained before and after the retrofitting works demonstrate that the ambient vibration tests and the data processing techniques used allow the identification of the dynamic behavior of r.c. few-storeys buildings under operating conditions and, then, the identification of dynamic changes due to seismic retrofitting works performed with external steel “dissipative towers”. A model updating procedure is carried out to identify the value of the elastic modulus of the different materials constituting structural and non-structural elements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233480 Collegamento a IRIS

2014
Risposta sismica di pile fondate su gruppi di pali inclinati
Atti delle Giornate A.I.C.A.P. 2014
Autore/i: Morici M.; Carbonari S.; Dezi F.; Gara F.; Leoni G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Questo lavoro indaga la risposta sismica di pile da ponte fondate su gruppi di pali inclinati tenendo conto dell’interazione terreno-struttura e considerando gruppi di pali con differente geometria e caratterizzati da pali con diversa inclinazione. Le analisi di interazione sono eseguite ricorrendo al metodo per sottostrutture ed utilizzando, per le analisi di interazione cinematica delle palificate a pali inclinati, un modello numerico 3D agli elementi finiti sviluppato dagli autori. In particolare, i pali sono modellati con elementi trave mentre il terreno è schematizzato come un mezzo visco-elastico costituito da strati orizzontali indefiniti tra loro indipendenti. L’interazione palo terreno e palo-terreno-palo è colta nel dominio delle frequenze utilizzando funzioni elastodinamiche di Green che permettono implicitamente di tenere conto anche dello smorzamento geometrico e isteretico. Le sovrastrutture hanno un comportamento lineare e sono schematizzate con elementi trave. L’approccio per sottostrutture permette di indagare separatamente gli effetti cinematici ed inerziali in fondazione, al variare della geometria della palificata, e di evidenziare il contributo dell’interazione nella definizione del moto sismico per le analisi delle sovrastrutture (moto della fondazione). I risultati delle analisi permettono di esprimere delle prime considerazioni circa l'influenza della configurazione della palificata e dell'inclinazione dei pali sul comportamento strutturale delle pile (spostamenti e caratteristiche di sollecitazione) e sulla risposta delle fondazioni (massimi tagli e momenti flettenti nei pali dovuti all'interazione cinematica e inerziale).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/212146 Collegamento a IRIS

2014
Seismic response of bridge piers founded on inclined pile groups
Proceedings of the Second European Conference on Earthquake Engineering
Autore/i: Morici M.; Carbonari S.; Dezi F.; Gara F.; Leoni G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper investigates the seismic response of bridge piers founded on inclined pile groups, evaluating effects of soil-structure interaction by considering different pile group geometries and piles inclinations. Analyses are performed by means of the direct approach taking advantage of a 3D numerical model developed by the authors for the analysis of inclined pile groups. In particular, both the superstructure and piles are modelled by means of beam elements and the soil is schematized as a visco-elastic medium constituted by independent infinite horizontal layers. The soil-pile and the pile-soil-pile interaction are captured in the frequency domain by means of elastodynamic Green’s functions that also allow including the hysteretic and radiation damping. In order to investigate kinematic stress resultants in piles and to evaluate the significance of the soil-foundation system filtering effect, kinematic interaction analyses of the soil-foundation systems are also performed by removing the superstructure mass from the models. The influence of key parameters such as the piles inclination and the group configuration on the structural behaviour (displacements and stress resultants) and on the foundation response (maximum shears and bending moments in piles) is discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/212150 Collegamento a IRIS

2014
Ambient vibration tests on a reinforced concrete school building before and after retrofitting works with external steel "dissipative towers”
Proceedings of the IX Int. Conf. on Structural Dynamics, EURODYN
Autore/i: Roia, Davide; Gara, Fabrizio; Balducci, Alessandro; Dezi, Luigino
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper deals with the ambient vibration tests carried out on an existing reinforced concrete school building sited in Camerino, a small town in central Italy near the epicentre of Umbria-Marche 1996 earthquake. Tests were performed before and after the seismic retrofitting of the building achieved with of an innovative system that uses external steel dissipative towers. Before the retrofitting, ambient vibration tests were carried out with the aim of evaluating the actual linear dynamic behaviour of the building including the contribution of non-structural components (e.g. external and internal walls); modal parameters, i.e. natural frequencies and mode shapes determined by means of experimental modal analysis, allowed the calibration of a predictive f.e. model of the building which was crucial for the final design of the retrofitting system. Tests were repeated after the retrofitting works, with the main objective to verify that changes of modal parameters are in agreement with those predicted by the f.e. model. Tests were carried out by positioning low noise piezoelectric accelerometers opportunely so as to survey the rigid motion of each storey. The modal parameters were identified with two identification techniques, the Enhanced Frequency Domain Decomposition and the Covariance-driven Stochastic Subspace Identification, in order to assess whether a method is more suitable in such cases. Results and comparisons between the modal parameters obtained before and after the retrofitting works demonstrate that the ambient vibration tests and the data processing techniques used allow identifying the dynamic behaviour of r.c. few-storeys buildings under operating conditions and catching the changes due to seismic retrofitting works performed using external steel dissipative towers.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/225175 Collegamento a IRIS

2014
NONLINEAR DYNAMIC RESPONSE OF NEAR-SHORE PILES SUBJECTED TO SNAP-BACK TESTING
Proceedings of the 15th European Conf. on Earthquake Engineering and Seismology, 15ECEES
Autore/i: Francesca, Dezi; Fabrizio, Gara; Davide, Roia
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents the results of free vibration tests carried out on a near-shore steel pipe pile vibrodriven into soft marine clay. The tests were carried out by quickly releasing a free head pile from a deformed configuration obtained by applying a quasi-static horizontal loading by means of a hydraulic jack. Different tests were performed at increasing loading levels with the aim of investigating the dynamic soil-water-pile system interaction and investigating how the nonlinear dynamic behaviour develops as the applied load increases. The results of experimental modal analyses, based on the signals recorded by strain gauges applied along the pile, are presented in terms of natural frequencies and damping ratios of the soil-water-pile system and the variations with loading level, due to the nonlinear behaviour of the system, are discussed. The dynamic effects induced on two pipe piles vibrodriven near the loaded pile to form an L-shaped in plan configuration are also discussed on the basis of signals measured by accelerometers applied at the head of the receiver piles; in order to investigate the pile-to-pile dynamic interaction.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/225197 Collegamento a IRIS

2014
Analisi sismica di edifici prefabbricati con connessioni deformabili
Atti del Workshop tecniche innovative per il miglioramento sismico di edifici prefabbricati
Autore/i: Tassotti, Luca; Radi Mohamed; Gara, Fabrizio; , Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Nel contesto nazionale le strutture prefabbricate monopiano risultano in larga parte concepite mediante concezioni strutturali superate dagli attuali criteri antisismici. Gli eventi sismici recenti e del passato hanno evidenziato come la loro vulnerabilità sia spesso associata alle connessioni tra elementi strutturali. Le norme attuali risultano tuttavia carenti nel fornire indicazioni in merito alla progettazione e alla modellazione delle stesse. Nella presente memoria viene presentata una procedura di modellazione delle connessioni a spinotto per la valutazione della vulnerabilità sismica degli edifici esistenti. La metodologia proposta viene applicata a due capannoni industriali esistenti. Dai risultati delle analisi dinamiche lineari e statiche non lineari condotte è emerso che una modellazione delle connessioni rigide può portare a sovrastime della domanda sismica in esse e alla variazione della risposta sismica globale dell’edificio, modificando l’esito delle verifiche di sicurezza sia globali che locali.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/234008 Collegamento a IRIS

2014
Lateral impact loading and snap-back testing to estimate linear and nonlinear dynamic response of near-shore piles
Proceedings of the 20th IMEKO TC-4
Autore/i: Dezi, Francesca; Gara, Fabrizio; Roia, Davide
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents some results of dynamic lateral loading tests on a near-shore steel pipe pile vibrodriven into soft marine clay. Two typologies of tests are carried out on a free head pile: impact load tests and free vibration tests at different load levels. The aim of this experimentation is to investigate the dynamic soil-water-pile interaction and determine the dynamic characteristics of the whole system by means of the two different typologies of test and for different levels of the dynamic input. The obtained results show the complex dynamic behaviour of the vibrating soil-water-pile system in terms of natural frequencies and damping ratios. The values obtained from the two test typologies are compared and the variations with the level of the input force, due to the nonlinear behaviour of the system, are discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/225196 Collegamento a IRIS

2014
The effect of tie beams on the kinematic response and impedence functions of monopile foundations
Proceedings of the Second European Conference on Earthquake Engineering
Autore/i: Capatti M.C.; Carbonari S.; Dezi F.; Gara F.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper focuses on the effect of tie beams on the kinematic response and impedance functions of monopile foundations. Considering a foundation system of a regular framed structure, constituted by monopiles connected with tie beams, a representative portion of the foundation is isolated by suitably modelling its boundary conditions, and kinematic Soil-Structure Interaction analyses are performed exploiting the numerical formulation proposed by Dezi et al. (2009) for the soil-pile system modelling. The model assumes a linear behaviour for the pile and is able to include the soil non linearity in a linear equivalent manner; this allows formulating the problem in the frequency domain where elastodynamic Green’s functions are used to account for the soil-pile interaction and for both the hysteretic and radiation damping. Tie beams are included into the formulation and the problem is solved by means of the finite element approach. A non dimensional parametric investigation is performed by varying the main geometrical and mechanical parameters affecting the whole system response. Results are presented in terms of impedance functions and kinematic response parameters, focusing on the effects of the foundation tie beams on the system response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/212149 Collegamento a IRIS

2014
Seismic response of reinforced concrete frames on monopile foundations
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: CARBONARI, SANDRO; Dezi, F.; GARA, Fabrizio; Leoni, G.
Classificazione: 1 Contributo su Rivista
Abstract: The paper focuses on the effects of soil-structure interaction on the seismic response of reinforced concrete frames on monopile foundations connected by tie beams. Such systems are usually designed by considering fixed restraints at the column bases and the effects of the foundation compliance have not yet been investigated. The soil-foundation system is analysed in the frequency domain by means of a numerical model that allows obtaining the dynamic impedance functions of the system and the foundation input motion necessary for the subsequent nonlinear inertial soil-structure interaction analysis which is performed in the time domain. Tie beams with different stiffness and soil deposits characterised by three different profiles of shear wave velocity are considered. Results of incremental dynamic analyses carried out on frames with monopile foundations are compared with those obtained considering double-pile foundations and the fixed base assumption. Soil-structure interaction is found to affect considerably the response of frames on monopile foundations by increasing the structural deformation and modifying the evolution of the dissipative mechanisms. Analyses accounting for the actual soil-foundation system compliance and the foundation input motion may be crucial for a reliable prediction of the actual distribution of stresses in the superstructure and the foundation elements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/212137 Collegamento a IRIS

2014
Design expressions for the effective width of composite steel-concrete members
Proceedings of the 37th IABSE Symposium
Autore/i: Gara, Fabrizio; Ranzi, Gianluca; Leoni, Graziano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents a new approach for the evaluation of the effective width for the analysis of composite steel-concrete members. The proposed method is based on the use of simple expressions which enable the calculation of the effective width of the slab accounting for shear-lag effects. Its particularity relies on its ability to utilize the results of a global analysis carried out specifying the real width of the slab along the whole bridge length and to port-process these by means of a crosssectional analysis using simple design equations to define the geometry of the concrete slab. The expressions for the effective widths have been derived for different loading conditions including constant uniformly distributed loads, envelopes of transverse actions due to traffic loads, support settlements, thermal effects and shrinkage. Several applications are then presented to outline the ability of the proposed method to accurately predict the stress state in the concrete slab while accounting for shear-lag effects. These results are also compared against those obtained based on available design guidelines and calculated by means of the finite element method using line and shell elements
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/225195 Collegamento a IRIS

2014
A higher order steel-concrete composite beam model
ENGINEERING STRUCTURES
Autore/i: GARA, Fabrizio; CARBONARI, SANDRO; G., Leoni; DEZI, LUIGINO
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents a model for the analysis of composite beams in which the constrained kinematics encompasses the overall shear deformability, warping of the slab cross section and of the steel beam and partial shear interaction between slab and girder. The warping functions are obtained by considering the problem of unrestrained thin-walled members subjected to self-equilibrated elementary load schemes. The governing equations are derived, according to the stiffness method, both in the weak and strong forms starting from the Virtual Work theorem which makes it possible to consistently obtain the resultants of stresses, the applied forces and the inertia involved in the problem. The analytical solution is obtained from the governing differential equations and the relevant boundary conditions exploiting exponential matrices. Some simple applications show the capability of the model to accurately describe both the global behaviour of composite beams, in terms of displacements and stress resultants, and local effects, in terms of normal stresses. The comparisons with results obtained with a refined shell finite element model are very satisfactory.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/212143 Collegamento a IRIS

2013
Slab cracking influence in the fatigue assessment of continuous composite bridge decks
Proceedings of the 36th IABSE Symposium
Autore/i: Dezi L.; M. Formica; Gara F.; Leoni G.
Editore: Editore IABSE-ETH Honggerberg, Zurich, Switzerland
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper analyzes the influence of the slab cracking in the fatigue assessment of continuous composite decks by considering the effects of slab casting sequences and the shrinkage components (thermal, endogenous and drying). A numerical procedure for the stress calculation accounting for the tension stiffening of the slab longitudinal rebars is presented. The long term effects of casting sequences and concrete shrinkage are analysed with a simplified procedure based on the application of the modular ratio method. With reference to a realistic continuous twin girder composite deck the fatigue verification of the longitudinal girders is carried out by considering three different casting modalities. The obtained results show the important role of the slab casting sequences in the stress range calculation and the remarkable influence of the slab cracking in the fatigue assessment.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/163748 Collegamento a IRIS

2013
Dynamic tests on an existing r.c. school building retrofitted with external steel "dissipative towers
Proceedings of the Int. Conf. on Vibration Problem ICOVP
Autore/i: Roia D.; Gara F.; Balducci A.; Dezi L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper deals with the dynamic tests carried out on a school building (four story reinforced concrete frame) seismically retrofitted with an innovative system that uses external steel dissipative towers. Before the retrofitting, ambient vibration tests were carried out with the aim of evaluating the actual linear dynamic of the building including the contribution of non-structural components (e.g. external and internal walls). Modal parameters determined by means of experimental tests are crucial for the final design of the retrofitting system allowing the calibration of a predicting f.e. model. Three low noise servo-accelerometers per floor were opportunely positioned at each floor to monitor its rigid motion. The modal parameters are identified with the Enhanced Frequency Domain Decomposition technique obtaining the natural frequencies, mode shapes and damping ratios. After the building retrofitting, snap-back tests at different load levels were performed in order to evaluate the dynamic characteristics of the new structural system. The load was applied in a quasi-static manner by means of two Dywidag bars 47 anchored at the last floor and connected to a steel triangular truss pulled by two hydraulic jacks; the instantaneous release was obtained by cutting a dog-bone shaped steel plate with a blowtorch. In addition to the accelerometers, displacement transducers were positioned at the base of the steel towers, close to the viscous dampers, to measure the motion of the two towers. The natural frequencies and the damping ratios of the retrofitted building are estimated from the time histories of accelerations (free decay functions) by means of the crossing time and the logarithmic decrement techniques, respectively. The adopted experimental methodology adopted has revealed to be effective for the dynamic characterization, both at very low strain and at higher strain level, of a low-rise reinforced concrete frame building in service, which is characterized by a high overall stiffness due to the contribution of the non-structural components.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/163746 Collegamento a IRIS

2013
Full-scale pile subjected to different lateral dynamic loadings
Proceedings of the Int. Conf. on Earthquake Geotechnical Engineering ICEGE
Autore/i: Dezi F.; Gara F.; Roia D.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents some results of dynamic lateral loading tests on a near-shore steel pipe pile vibrodriven into soft marine clay. Two typologies of tests are carried out on a free head pile: impact load tests and free vibration tests at different load levels. The aim of this experimentation is to investigate the dynamic soil-water-pile system interaction and determine the dynamic characteristics of the whole system by means of two different typologies of test and for different levels of the dynamic input. The obtained results show the complex dynamic behaviour of the vibrating soil water pile system in terms of natural frequencies and damping ratios. The values obtained from the two test typologies are compared and the variations with the level of the input force, due to the nonlinear behaviour of the system, are discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/163744 Collegamento a IRIS

2013
Interdependent interpolation element for shear deformable composite beams
Atti del XXIV Congresso C.T.A.
Autore/i: Carbonari S.; Dezi L.; Gara F.; Leoni G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents a novel interdependent interpolation finite element for a higher order beam capable of capturing shear-lag phenomenon and overall shear deformability of composite beams. After a brief overview of the beam kinematics and of the differential solving equations, the stiffness matrix and the nodal forces to be applied in a standard finite element procedure are derived in a consistent way by exploiting properties of exponential matrix ad their application in the solution of linear differential equation systems. Some comparisons with solutions obtained by using finite elements with polynomial interpolating functions demonstrate the capability of the new element.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/163559 Collegamento a IRIS

2013
Slab Cracking Control in Continuous Steel-Concrete Bridge Decks
JOURNAL OF BRIDGE ENGINEERING
Autore/i: GARA, Fabrizio; Graziano, Leoni; DEZI, LUIGINO
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents a study on the effectiveness of various casting techniques used to control slab tensile stresses during the construction of continuous steel-concrete composite bridge decks. The main features describing the early age behavior of concrete are outlined and available modeling options are considered. A practical procedure is presented for the evaluation of the slab stress state taking place at various construction stages based on the modular ratio approach suggested by Eurocode 4. The method, which can be implemented using commercial software, requires the evaluation of suitable modular ratios and creep coefficients to estimate the time-dependent effects of the concrete slab weight and the thermal, endogenous, and drying shrinkage components. This simplified procedure is then applied to a case study to evaluate, for various casting sequences, the contributions of the concrete weight and shrinkage components to the slab early cracking. Finally, the efficiency of various casting techniques in controlling the slab tensile stresses is presented and discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/133462 Collegamento a IRIS

2013
Experimental study of near-shore pile-to-pile interaction
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
Autore/i: F., Dezi; GARA, Fabrizio; ROIA, DAVIDE
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents the results of lateral impact load field tests carried out on a system of three steel pipe piles vibro-driven into soft clay in a near-shore marine environment, with the aim of evaluating the pile-soil-pile dynamic interaction. Piles are arranged in an “L” shaped horizontal layout and are instrumented with accelerometers at their free heads. The obtained results show the complex dynamic behaviour at very small strain of the vibrating soil water piles system. The role of different type of waves in the pile to pile interaction is investigated by analyzing the results in the time and frequency domains and by means of a time-frequency analysis. The effects of the pile spacing and input direction on these interaction mechanisms are also presented. Finally, important dynamic parameters of the soil, such as the velocities of the shear waves and surface waves (Scholte waves) of the upper soil are directly estimated from the time delays between signals recorded at the pile heads.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/90264 Collegamento a IRIS

2013
A comparative study on the time-dependent analysis of composite beams using available modelling techniques
Applied Mechanics and Materials - Advances in Computational Mechanics
Autore/i: O. Vallati; F. Gara; G. Ranzi; G. Leoni
Editore: Publishing Editor Wolhlbier T., USA
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents a comparison of available numerical structural formulations for the short- and long-term analysis of composite beams with partial shear interaction. Four methods of analysis are considered and these include the finite difference method, the finite element method, the direct stiffness method and the exact analytical model. The results btained using these formulations are compared qualitatively and their accuracy is estimated, adopting the exact analytical model as a benchmark reference with the objective of establishing the minimum spatial discretisations required to keep the error within an acceptable tolerance. These comparisons are carried out for two static configurations, i.e. simply-supported beams and propped cantilevers, from which the qualitative behaviour of these formulations in the modelling of continuous beams can also be deduced.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/175703 Collegamento a IRIS

2013
Simplified method to analyse casting sequence of composite bridge slabs
Proceedings of the 36th IABSE Symposium
Autore/i: Dezi L.; Gara F.; Leoni G.
Editore: IABSE-ETH Honggerberg, Zurich, Switzerland
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper presents a simplified procedure to analyse the effects of construction sequences of slabs in steel-concrete composite bridge decks. The procedure allows accounting for shrinkage and casting sequence effects. The time-dependent behaviour of the concrete is also included to capture the stress relaxation that mitigates the effects of the fast thermal shrinkage. Main features related to modelling of early-age concrete behaviour and tensile creep are discussed. The proposed simplified method is applied to evaluate the stresses in the slab of a realistic three-span composite bridge deck by considering different casting sequences. The comparison between the results obtained with the proposed method and those given by a step-by-step procedure shows the accuracy of the simplified method that can be considered a useful tool for practical applications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/163747 Collegamento a IRIS

2013
Tests on two 18-years-old prestressed thin walled roof elements
ENGINEERING STRUCTURES
Autore/i: CARBONARI, SANDRO; GARA, Fabrizio; ROIA, DAVIDE; G., Leoni; DEZI, LUIGINO
Classificazione: 1 Contributo su Rivista
Abstract: The paper presents the experimental tests carried out on two prestressed thin walled V-shaped elements, used over a period of 18 years as the roof of an industrial building and removed after having exhibited marked deflections and crack patterns. The experimental program, including material characterization, impact load and ultimate static load tests, is aimed at valuating the actual load carrying capacity of the elements. The survey of the elements geometry, with special attention to imperfections, is presented; then results of the impact load test, namely the fundamental frequencies and modal shapes of free vibration, are reported. Successively, the results of static load tests up to failure are discussed. Due to the small thickness of the cross section walls, second order effects strongly interact with the global failure mechanism. The combination of dynamic impact and ultimate static load tests allowed the calibration of an accurate finite element model, accounting for both mechanical and geometrical nonlinearities, capable to predict the behaviour of the elements up to collapse and useful to design repairing and strengthening works.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/86615 Collegamento a IRIS

2012
Effects of soil-foundation flexibility on the performance of reinforced concrete frame structures
Proceedings of the 2nd Int. Conf. on Performance Based Design in Earthquake Geotechnical Engineering, IIPBD
Autore/i: Dezi, F.; Carbonari, S.; Gara, F.; Leoni, G.
Editore: Pàtron Editore
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper focus on the effects of soil-structure interaction on the seismic response of reinforced concrete frames designed according to displacement-based approaches and founded on piles. The substructure method is adopted and 6-storeys 3-bays frames founded on 3 different two-layered soil deposits are considered. For each soil deposit two foundation typologies are adopted: mono-pile and double-pile foundations. Soil-structure interaction effects on the seismic response of the structures are evaluated both in the linear and nonlinear field by means of incremental dynamic analyses. Results, in terms of forces and displacements, are compared with those achieved from conventional fixed base analyses demonstrating that soil-structure interaction effects are more evident for moderate earthquakes, inducing early structural damages, and for soft soil deposits. For earthquakes of high intensity soil-structure interaction is less important. The mono-pile foundation, suitably designed in conjunction with stiff tie-beams, is able to guarantee an efficient degree of restraint at the base of columns, comparable with that provided by the double-pile foundation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/74916 Collegamento a IRIS

2012
Seismic response of reinforced concrete frames on pile foundations
Proceedings of the 18th IABSE Congress on Innovative Infrastructures – Towards Human Urbanism
Autore/i: Dezi F.; Carbonari S.; Gara F.; Leoni G.
Editore: IABSE-ETH Honggerberg
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The paper focus on the effects of soil-structure interaction on the seismic response of reinforced concrete frames founded on piles. The substructure method is adopted and 6-storeys 3-bays frames founded on 3 different two-layered soil deposits are considered. For each soil deposit two foundation typologies are adopted: mono-pile and double-pile foundations. Soil-structure interaction effects on the seismic nonlinear response of the structures are evaluated by means of incremental dynamic analyses. Results are compared with those achieved from fixed base analyses demonstrating that soil-structure interaction effects are more evident for moderate earthquakes, inducing early structural damages, and for soft soil deposits. The mono-pile foundation, suitably designed in conjunction with stiff tie-beams, is able to guarantee an efficient degree of restraint at the base of columns, comparable with that provided by the double-pile foundation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82712 Collegamento a IRIS

2012
Effects of Soil-Structure Interaction on the Linear and Nonlinear Seismic Behaviour of Coupled Wall-Frame Systems
Dynamic Interaction of soil and structure (DISS_12)
Autore/i: Carbonari, Sandro; Dezi, Francesca; Gara, Fabrizio; Leoni, Graziano
Editore: Aracne
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The effects of Soil-Structure Interaction (SSI) on the response of coupled wall-frame structures on pile foundations are investigated. The analysis methodology based on the substructure method is re-called focusing on the modelling of pile group foundations. The iner-tial interaction analysis is performed in the time domain by using a fi-nite element model of the superstructure and suitable Lumped Pa-rameter Models (LPMs) are implemented to reproduce the frequency-dependent compliance of the soil-foundation systems. The effects of SSI are evaluated by considering realistic case studies consisting of 6-storey 4-bay wall-frame structures founded on piles. Moderate and strong seismic actions are simulated employing real and artificial earthquakes. The superstructure is assumed to behave linearly under moderate shakings; on the other hand, the nonlinear structural behav-iour is accounted for in the case of strong earthquakes. Comparisons of the results obtained considering compliant base and fixed base models are presented by addressing the effects of SSI on the main re-sponse quantities of linear and nonlinear structures. SSI effects on displacements, inter-storey drifts and base shears are discussed and, with reference to the nonlinear structures, effects on the ductility de-mand and the evolution of dissipative mechanisms are investigated by considering earthquakes with increasing intensity.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/225215 Collegamento a IRIS




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