Dipartimento di Ingegneria Civile - Tesi di Dottorato

Permanent URI for this collectionhttps://lisa.unical.it/handle/10955/99

Questa collezione raccoglie le Tesi di Dottorato Dipartimento di Ingegneria Civile dell'Università della Calabria.

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Author: search.filters.author.Conte, EnricoStart date: 2020

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Now showing 1 - 4 of 4
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    Probabilistic assessment of the seismic performance of two earth dams in Southern Italy using simplified and advanced constitutive models
    (Università della Calabria, 2021-06-16) Regina, Gianluca; Conte, Enrico; Cairo, Roberto; Zimmaro, Paolo; Ziotopoulou, Katerina
    The large majority of existing earth dams were designed with old standards, which often accounted for the effects of earthquakes in a simplified manner. Nowadays, safety assessment of these structures is becoming of great importance, particularly for dams suffering the effects of ageing. This study presents a fully probabilistic approach to evaluate the seismic performance of two critical earth dams in the Calabria region, a seismically active area in Southern Italy. One of them (the Farneto del Principe dam) is not susceptible to liquefaction, whereas the other dam (the Angitola dam) is founded on potentially liquefiable soils. Seismic input motions are derived from site-specific probabilistic approaches. Non-ergodic ground response is implemented within a probabilistic seismic hazard analysis (PSHA) framework for one of the two dam sites. This non-ergodic PSHA is derived from numerical amplification functions based on one-dimensional simulations. Such well-documented early application of non-ergodic PSHA for earth dams in Italy may encourage a transformational shift from years of past practices based on deterministic amplification functions merged with PSHA results by means of hybrid approaches. Simplified (i.e., using the Mohr–Coulomb failure criterion coupled with a simplified hysteretic procedure) and advanced (i.e., PM4Sand and PM4Silt) constitutive models are used to perform a comprehensive numerical simulation program for both dams. Field and laboratory geotechnical characterization data are used to calibrate these models. This calibration process is fully documented and potential issues discussed. Such fully-documented calibration process will enable future studies on similar infrastructure systems when advanced constitutive models are necessary. Shear strain and deformation patterns are analyzed and discussed, showing that for the Farneto del Principe dam (comprising non-liquefiable materials) both constitutive models provide similar results. However, when potentially liquefiable soils are involved, advanced constitutive models are necessary to capture the complexity and nuances of such materials. This effect is evident for the Angitola dam. For both dams, seismic vulnerability is analyzed by means of analytical fragility functions for various damage mechanisms and intensity measures. Such fragility functions are based on nonlinear deformation analyses within the multiple stripe analysis framework. All fragility functions derived in this study are shown and main outcomes are illustrated by summary tables reporting mean and standard deviation values of these curves. Finally, the efficiency and predictability of various ground motion intensity measures to predict different damage levels and mechanisms are calculated for both dams. Predictability of recent semi-empirical ground motion models is also calculated for all analyzed intensity measures. Overall, results from this analysis indicate that velocity-based ground motion properties, such as Peak Ground Velocity, Arias Intensity, Cumulative Absolute Velocity, and Cumulative Absolute Velocity after application of a 0.05 𝑚𝑠2 threshold acceleration provide good efficiencies in predicting damage. These intensity measures are the best in predicting damage states for both dams and all damage mechanisms. However, some of them are more predictable than others. After merging efficiency and predictability information, the best intensity measure to predict damage is the Cumulative Absolute Velocity, followed by the Arias intensity.
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    Analisi teorica/sperimentale di travi in calcestruzzo armato rinforzate con sistemi Steel-FRCM: caratterizzazione dei materiali/comportamento strutturale sotto carico monotono e ciclico/valutazione della deformazione di distacco intermedia
    (Università della Calabria, 2021-06-25) Nisticò, Mattia; Conte, Enrico; Bencardino, Francesco
    Il presente lavoro di tesi si propone di studiare il comportamento strutturale di travi di calcestruzzo armato (c.a.) in scala reale sottoposte a caricamento monotono e ciclico, rinforzate esternamente con sistema Steel-Fabric Reiforced Cementitious Matrix (S-FRCM). Le travi testate a flessione sono rinforzate con una tecnica tradizionale Externally Bonded (EB) e con una tecnica innovativa chiamata Inhibiting-Repairing-Strengthening (IRS) che prevede l’applicazione del sistema di rinforzo all’interno del ricoprimento di calcestruzzo con una opportuna matrice inorganica a base di polimeri di natura minerale, avente proprietà di inibizione dalla corrosione delle armature interne. I risultati sperimentali hanno evidenziato l’efficacia della tecnica IRS che, rispetto alla tecnica tradizionale EB, ha fatto registrare maggiori incrementi di carico ultimo e di fattore di duttilità. Inoltre, l’uso di una fibra di acciaio con scarsa capacità di impregnazione favorisce la modalità di collasso per debonding che ne riduce la capacità di rinforzo. Sono state, inoltre, condotte prove di adesione su provini di calcestruzzo e muratura allo scopo di indagare e comprendere il comportamento di interfaccia dei sistemi S-FRCM al variare della tipologia di fibra di acciaio e matrice di applicazione. Il distacco all'interfaccia fibra-matrice e fibra-supporto (senza asportazione della superficie di applicazione) sono le principali modalità di rottura osservate, oltre alla rottura per trazione della fibra. Dai risultati ottenuti sono state calibrate leggi coesive di interfaccia per le applicazioni dei sistemi di rinforzo su elementi di calcestruzzo da utilizzare nelle analisi teoriche. I risultati sperimentali delle travi sono stati confrontati con i risultati ottenuti da un modello numerico agli elementi finiti utile per validare le leggi di interfaccia e prevedere il comportamento strutturale delle travi rinforzate con sistema EB-IRS/S-FRCM. Infine, sono state effettuate considerazioni sulla valutazione della deformazione di distacco intermedia (intermediate debonding) di strisce di acciaio applicate su elementi di c.a. secondo le indicazioni riportate nel documento CNR-DT/215. I confronti sono stati eseguiti utilizzando i dati sperimentali ottenuti nello sviluppo della tesi ed un database di risultati collezionati dalla letteratura scientifica. Il confronto è effettuato anche con semplici formule predittive proposte da diversi autori. Da questi confronti si evince come le indicazioni del documento CNR-DT/215 forniscano risultati affidabili per le fibre con bassa densità ed al contrario errori non trascurabili XII nel caso di fibre di acciaio ad alta densità. Le formule predittive, caratterizzate dalla facilità d’uso, indicano valori accurati in combinazione con opportuni coefficienti parziali di sicurezza.
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    Analisi sismica non lineare di edifici con struttura in C.A. base fissa ed isolata in presenza di fenomeni di martellamento interno ed esterno
    (Università della Calabria, 2021-06-09) Labernarda, Rodolfo; Conte, Enrico; Mazza, Fabio
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    The quality of air transport service
    (Università della Calabria, 2021-03-25) Bellizzi, Maria Grazia; Conte, Enrico; Eboli, Laura
    The socioeconomic development of a country necessarily relies on the improvement of all transport services. With the introduction of new technologies, transport industry has developed considerably in recent years, and as a consequence people habits and travel choices changed as well. In this context, air transport has a significant role, and it could be considered one of the most significant contributors to the advancement of modern society. Evaluating air transport service quality is important as it is for the other public transport systems. Airport facilities and services are the first experiences that a passenger receives upon arrival. For this reason, providing airport services characterized by high levels of quality is very important to make the travel more pleasant for the passengers, with the final objective to attract more users. Therefore, measuring the levels of airport services by evaluating passengers’ satisfaction with them is essential to understand the needs of customers. In the same way, with the airlines’ deregulation the number of airlines entered into the air transport industry significantly increased, causing a stronger competition. In this context, it is evident that provided service quality, as well as passengers’ satisfaction, play an important role also in the airlines marketing strategies. While literature regarding the evaluation of road and rail public transport service quality is well established from many years, literature concerning air transport service quality is relatively recent. A first substantial issue that emerges from the air transport related literature concerns the complexity of the various characteristics of the services, which can relate to the airport managing companies and to the airlines. For this reason, the major part of the studies treats separately these two groups of service. Specifically, the researchers analysed air transport services by distinguishing the concerning the services offered in the airports from the ones provided by the airlines. The aim of this thesis work is to give a contribution to the existing literature, by applying various techniques and models for analysing both airport and airlines’ service quality. As suggested by the literature, also in this work the airport services have been treated separately by the airlines’ services. In fact, two different data samples were analysed. Specifically, the International airport of Lamezia Terme (Italy) has been considered as case study for the airport services. Otherwise, data collected by an online survey conducted at the University of Calabria (Italy) became object of study for the airlines’ services analyses. Several tools have been tested and proposed. The obtained results could be considered not only as a research contribution, but also as starting point to help air transport managers and providers in choosing the effective strategy for providing services characterized by adequate levels of quality.