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Ligabue, Veronica. "Criteri di selezione degli accelerogrammi registrati per la progettazione di strutture in zona sismica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2607/.
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Cristalli, Sara. "Modellazione numerica della risposta sismica locale dei terreni di fondazione delle due torri di Bologna." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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La città di Bologna, così come tutta la penisola italiana, fa parte di un territorio in cui il rischio sismico è elevato. In questo lavoro di tesi viene proposto un modello numerico del terreno di fondazione delle Due Torri di Bologna sviluppato al fine di analizzarne la risposta sismica locale.
Con lo scopo di ottenere un modello rappresentativo più possibile delle condizioni reali è stato eseguito un accurato studio geologico, geotecnico e sismico del substrato in esame. La selezione degli input sismici da utilizzare durante le analisi è avvenuta mediante l’uso del software REXEL e, in particolare, si è fatto riferimento all’European Strong Motion Database (ESD). La validazione del modello sviluppato è avvenuta attraverso il confronto dei risultati tra il codice di calcolo PLAXIS e un codice di calcolo che svolge analisi visco-elastiche lineari nel dominio delle frequenze, MARTA.
È stata, quindi, analizzata l’influenza che possono avere l’estensione del modello e le condizioni al contorno di base (linear elastic o compliant base) ai fini della valutazione della risposta sismica locale, insieme con la variazione delle condizioni al contorno laterali, viscous o tied degrees of freedom. Inoltre, si sono valutati gli effetti di input sismici di diversa entità.
Nel caso specifico, si è visto che impiegare un contorno laterale del tipo tied degrees of freedom ha apportato dei vantaggi, sia per l’affidabilità dei risultati che sono gli stessi ricavati mediante MARTA, sia per il fattore tempo. Di contro, si è visto che per bassi livelli tensionali, PLAXIS potrebbe sottostimare la rigidezza.
I risultati ottenuti nell’ambito di questo progetto di tesi costituiscono un punto di partenza per eventuali studi futuri, che prevedono la realizzazione di strutture tali da simulare le Due Torri, per analizzare l’interazione dinamica terreno/struttura.
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Costantino, Antonio Beniamino. "Correlazione tra i parametri di intensità di un sisma e il danno procurato alle costruzioni: rilievi di campo e studio di una proposta metodologica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Con questa tesi è stata studiata una metodologia per la previsione di scenari di danno post terremoto. La procedura, basata su un approccio empirico, è stata sviluppata per categorie di costruzioni con caratteristiche strutturali e dinamiche omogenee, e si applica a scala territoriale.
Il procedimento consiste nell’associare al danno procurato da uno o più eventi i corrispondenti parametri di intensità sismica e conservare l’informazione in schede di correlazione, in modo da farne uso, come riferimento, in caso di nuovo evento sismico. La consultazione di tali schede, che costituiscono un archivio degli effetti causati da una serie di eventi per la categoria di costruzioni in esame, permette di formulare una previsione di danno non appena si dispone dei parametri di intensità del nuovo evento. La procedura è stata applicata nel caso degli edifici produttivi emiliani costruiti in assenza di criteri antisismici. Sono state analizzate le scosse, di magnitudo maggiore di 5, avvertite in Emilia a partire dal 1996 (crisi sismica EMILIA 2012, terremoto di Poviglio (PR) del 2012, terremoto di Bagnolo in Piano (RE) del 1996), aventi l’epicentro in zone con un’alta densità di edifici appartenenti alla categoria in esame. L’indagine ha permesso di individuare una prima ipotesi di soglie di danno, riferite principalmente, nel caso degli edifici produttivi, a parametri di intensità sismica dipendenti dalla velocità e dallo spostamento. La procedura è stata applicata inoltre nel caso della sequenza sismica del Centro Italia (2016-2017) per gli edifici in muratura di Norcia (PG) e per gli edifici produttivi di Arquata del Tronto (AP) e Muccia (MC).
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Fabrizio, Yari. "Miglioramento sismico di un telaio in c.a. con pannelli dissipativi ad attrito." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Miglioramento sismico di una struttura esistente in c.a. locata nel comune di Rimini, tramite l'introduzione di sistemi di controventamento e pannelli dissipativi in legno ad attrito. Dove tali sistemi consento di ridurre gli spostamenti e le sollecitazioni, che in loro assenza andrebbero a danneggiare il telaio in c.a. e i vani ascensore.
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Catti, Paolo. "Analisi sismiche di un edifico esistente in c.a.: progettazione di sistemi di dissipatori fluido-viscosi in presenza di escursione plastica di travi e pilastri." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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L’obbiettivo della tesi è quello di andare a contestualizzare il metodo "Direct Five Step Procedure" (DFSP) per la progettazione di un sistema di dissipatori fluido-viscosi in un adeguamento/miglioramento sismico di un edificio esistente ed integrando la procedura tenendo conto della capacità duttile della struttura. Per fare ciò si è preso in esame un edificio esistente situato a L’Aquila caratterizzato da un rapporto C/D (capacità/domanda) intorno a 0.2-0.3 così da rendere necessario l’accoppiamento di dissipazione viscosa tramite smorzatori e di dissipazione isteretica attraverso il danneggiamento negli elementi strutturali (travi e pilastri).
Imponendo come condizione η = ηξ * ηq (fattore di riduzione della risposta sismica costituito da due contributi: uno viscoso ed uno isteretico) ed utilizzando la DFSP per la progettazione degli smorzatori viscosi si è andato a studiare il comportamento della struttura tramite analisi dinamiche non lineari (come imposto da normativa), utilizzando diverse taglie di smorzatori e confrontando i fattori di riduzione di target e quelli ottenuti a valle delle analisi.
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Buratti, Nicola <1980>. "Assessment of Seismic Safety: Response Surface Approach and Accelerogram Selection Issues." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1967/.
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Hancock, Jonathan. "The influence of duration and the selection and scaling of accelerograms in engineering design and assessment." Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/7176.
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Tayebi, Abdelkader Kamel. "An evaluation of spectrum-compatible accelerograms for nonlinear analysis of short-period structures located in eastern Canada." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26428.
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Smooth design spectra are generally used to describe the seismic excitation provided by the maximum design earthquake for safety evaluation of critical facilities located in Eastern Canada. However, a comprehensive study of the inelastic behaviour of critical structural systems requires step-by-step inelastic analysis in the time domain.This thesis presents a study of inelastic seismic analysis of short-period structures subjected to ground motion acceleration time histories compatible with Eastern Canadian conditions and defined (i) from historical records scaled to the smooth design spectrum intensity, (ii) from spectrum-compatible accelerograms generated by random vibration theory, and (iii) from the modification of the Fourier Spectrum coefficients of historical records while preserving the original phase angles. The ductility demand, the input energy, the hysteretic energy, the number of yield events, and other performance indices, are examined in parametric analyses to identify the type of earthquake motions that is critical for earthquake resistant design of ductile short-period structures. The linear and cracking responses of concrete gravity dams of three different heights (90m, 45m, and 22.5m), that exhibit a brittle response to strong ground shaking, are also examined for the different types of spectrum-compatible accelerograms. It is generally concluded that in the absence of suitable spectrum-compatible historical accelerograms, either historical records with modified Fourier spectra or synthetic records can be used to evaluate the linear structural response. For nonlinear analysis, historical records with modified Fourier amplitude spectra tend to produce closer results to those obtained from real earthquakes for cumulative damage indices, as compared to the results computed from synthetic accelerograms.
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Gariel, Jean-Christophe. "Simulation numérique des mouvements forts en champ proche." Grenoble 1, 1988. http://www.theses.fr/1988GRE10080.
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Dans cette etude, on applique la methode des nombres discrets qui permet le calcul du rayonnement de sources etendues de mecanisme quelconque dans un milieu stratifie. On simule ensuite trois evenements de magnitude moderee, a imperial valley, a san salvador et a kalamata
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Quintero, Patrícia Murad. "Análise sísmica no domínio do tempo versus no domínio da frequência para uma ponte em seção celular." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-13042017-114109/.
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Este trabalho apresenta um estudo comparativo entre análises no domínio do tempo e análises espectrais, como forma de sugerir uma abordagem alternativa para o projeto de pontes de seção celular submetidas à ação de terremotos. Com esse propósito, desenvolveu-se um programa em linguagem JAVA para a geração de sismos artificiais, usando como base o Eurocode 8. A saída do programa foi utilizada para o desenvolvimento de um estudo de caso, que consiste em uma modelagem simplificada no software ADINA, de um vão de 21 m da Ponte Alverca, em Portugal. Após a extração e comparação de resultados dos dois métodos, é possível perceber que o método alternativo proposto - no domínio do tempo, que consiste na aplicação de acelerogramas artificiais ao modelo - possui resultados bastante coerentes com a análise espectral, além de ser mais recomendado se efeitos geométricos ou fisicamente não lineares forem considerados na modelagem.This work presents a comparative study between time-domain analysis and spectral analysis, as a way of suggesting an alternative approach for treating cell section bridges subjected to earthquakes. To reach this goal, it was developed a program in JAVA language for the artificial earthquakes generation, using the Eurocode 8 as a basis. The program output was used for a case study that consists in a simplified modeling using ADINA software, of a twenty-one-meter-long span of Alverca Bridge, in Portugal. After the results extraction of both methods, it is possible to notice that the alternative method - in the time-domain, which consists of the application of artificial accelerograms to the model - has fairly consistent results with spectral analysis, not to mention that it is the most suitable one, in case geometrical or physical non-linearities are considered in the modelling.
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Ruggeri, Lorenzo. "Analisi di risposta sismica locale per una cassa di espansione delle piene sul torrente Samoggia(Loc. Le Budrie, S. Giovanni in Persiceto)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2634/.
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Galin, Sanja. "Selection and Scaling of Seismic Excitations for Time-History Analysis of Reinforced Concrete Frame Buildings." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20657.
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Time history-analyses of building structures have been used for a quite long time for research at universities. Considering the advantage of time-history analysis relative to the equivalent static force method, the National Building of Canada and other modern building codes around the world require the use of time-history analysis in the design of specified types of buildings located in seismic regions. One of the main issues in the use of time-history analysis is related to the selection and scaling of the seismic excitations (i.e., accelerograms) to be compatible with the design spectrum for the location considered. Currently, both recorded (i.e., “real”) accelerograms and artificial accelerograms are used in the analyses.
The objective of this study is to determine the effects of the selection and scaling of seismic excitations on the response of reinforced concrete frame buildings. Three reinforced concrete frame buildings with heights of 4 storey, 10 storey and 16 storey, designed for Vancouver (high seismic zone) were used in this study. Five sets of seismic excitations were used in the analysis – one set of “real” accelerograms, and four sets of artificial accelerograms obtained by different methods. All sets were scaled to be compatible with the design spectrum for Vancouver. Both linear and nonlinear time history analyses were conducted on the buildings considered. Interstorey drifts and storey shear forces were used as response parameters.
The results from the linear analysis show that both the interstorey drifts and the shear forces are affected significantly by the type of the excitation set. Similarly, the effects of the type of the seismic excitations on the drifts from nonlinear analysis are substantial. On the other hand, the influence of the excitation sets on the storey shears from nonlinear analysis are quite small.
Based on the results from this study, sets of scaled real records are preferred for use in time-history analysis of building structures. If such records are not available, then sets of simulated accelerograms based on the regional seismic characteristics should be used.
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Brito, Ronnie Chtcot. "Acelerogramas artificiais de sismos aplicados a edificações." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-04012018-102406/.
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Apesar de fortes eventos sísmicos serem raros no Brasil, engenheiros estruturais brasileiros são frequentemente envolvidos em tal análise para os países latino-americanos vizinhos. Informações sobre históricos de aceleração sísmica, de natureza aleatória, não estão em geral disponíveis, devido, em parte, à falta de registros. Para contornar tal situação, os códigos de construção indicam o uso de acelerogramas artificiais, mas não fornecem metodologia para sua obtenção. A informação normalizada é o chamado espectro de resposta elástico, que fornece a aceleração de resposta máxima para um sistema linear de um grau de liberdade. Muitas pesquisas estão sendo desenvolvidas a fim de gerar acelerogramas artificiais compatíveis com os espectros de norma. Assim, neste trabalho se apresenta uma proposta para a geração de acelerograma artificial compatível com espectro de resposta regulamentar. Para exemplo de aplicação, é gerado um acelerograma artificial compatível com a Norma Brasileira NBR 15421: 2006 e aplicado à base de um edifício shear building de dez pavimentos e através de integração numérica por diferenças finitas passo-a-passo no domínio do tempo é calculado o deslocamento do último pavimento deste edifício. De forma semelhante, é gerado um acelerograma artificial compatível com a Norma Venezuelana COVENIN 1756: 2001 e aplicado à base de um reservatório d\'água sobre quatro pilares e estudado o seu comportamento elastoplástico perfeito.Although strong seismic events are rare in Brazil, Brazilian structural engineers are often involved in such an analysis for neighboring Latin American countries. Information on seismic acceleration histories of a random nature is not generally available, due in part to the lack of records. To circumvent such a situation, building codes indicate the use of artificial accelerograms, but do not provide a methodology for obtaining them. The normalized information is the so-called elastic response spectrum, which provides the maximum response acceleration for a linear system of a degree of freedom. Many researches are being developed in order to generate artificial accelerograms compatible with the norm spectra. Thus, this paper presents a proposal for the generation of an artificial accelerogram compatible with a regulatory response spectrum. For an application example, an artificial accelerogram compatible with the Brazilian Standard NBR 15421: 2006 is generated and applied to the base of a ten-story shear building and through numerical integration by finite differences step-by-step in the time domain is calculated the displacement of the last floor of this building. Similarly, an artificial accelerogram is generated that is compatible with the Venezuelan Standard COVENIN 1756: 2001 and applied on the basis of a water reservoir on four pillars and studied its perfect elastoplastic behavior.
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Domanic, Arman Kemal. "Effects Of Vertical Excitation On Seismic Performance Of Highway Bridges And Hold-down Device Requirements." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609297/index.pdf.
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ABSTRACT EFFECTS OF VERTICAL EXCITATION ON SEISMIC PERFORMANCE OF HIGHWAY BRIDGES AND HOLD-DOWN DEVICE REQUIREMENT
Domaniç, Kemal Arman M.S., Department of Civil Engineering Supervisor: Assist. Prof. Dr. Alp Caner February 2008, 152 pages Most bridge specifications ignore the contribution of vertical motion in earthquake analyses. However, vertical excitation can develop significant damage, especially at bearing locations as indeed was the case in the recent 1999 izmit Earthquake. These observations, combined with recent developments in the same direction, supplied the motivation to investigate the effects of vertical component of strong ground motion on standard highway bridges in this study. Reliability checks of hold-down device requirements per AASHTO Bridge Specifications have been conducted in this context. Six spectrum compatible accelerograms were generated and time history analyses were performed to observe the uplift at bearings. Selected case studies included precast pre-stressed I-girders with concrete slab, composite steel I-girders, post-tensioned concrete box section, and composite double steel box section. According to AASHTO specifications, hold-down devices were required in two cases, for which actual forces obtained from time history analyses have been compared with those suggested per AASHTO. The only non-linearity introduced to the analyses was at the bearing level. A discussion of effects on substructure response as well as compressive bearing forces resulting from vertical excitation is also included. The results of the study confirmed that the provisions of AASHTO governing hold-down devices are essential and reasonably accurate. On the other hand, they might be interpreted as well to be suggesting that vertical ground motion components could also be included in the load combinations supplied by AASHTO, especially to be able to estimate pier axial forces and cap beam moments accurately under combined vertical and horizontal excitations.
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Merenda, Dario Giuseppe. "Seismic mitigation of existing masonry structures by means of added damping and stiffness." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3266/.
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In this work seismic upgrading of existing masonry structures by means of hysteretic ADAS dampers is treated.
ADAS are installed on external concrete walls, which are built parallel to the building, and then linked to the building's slab by means of steel rod connection system.
In order to assess the effectiveness of the intervention, a parametric study considering variation of damper main features has been conducted. To this aim, the concepts of equivalent linear system (ELS) or equivalent viscous damping are deepen. Simplified equivalent linear model results are then checked respect results of the yielding structures.
Two alternative displacement based methods for damper design are herein proposed. Both methods have been validated through non linear time history analyses with spectrum compatible accelerograms.
Finally ADAS arrangement for the non conventional implementation is proposed.
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Castillo, Cano Ronald Daniel, and del Aguila Fredy Renan Young. "Análisis de la amplificación sísmica de edificios del Cercado de Lima – Lima y La Punta – Callao por medio del método modal espectral y tiempo – historia mediante acelerogramas sintéticos." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/652426.
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Actualmente la población limeña no cuenta con viviendas propias y seguras; por ello, surge el auge del rubro de la construcción masiva con grandes edificaciones multifamiliares, cuya resistencia al impacto telúrico de enorme magnitud de 8 a 9 grados sigue en prueba sísmica; por ende, es muy relevante realizar la comparación del análisis del método modal espectral de la estructura (desplazamientos y aceleraciones respecto al suelo) y un análisis del método tiempo-historia donde se obtendrán las deformaciones máximas de la estructura de los edificios en este presente estudio; asimismo, evaluará la vulnerabilidad de la construcción estructural mediante acelerogramas sintéticos utilizando como espectro objetivo el espectro de peligro uniforme obtenido en el Parque de la Reserva, Cercado de Lima, por medio de un estudio peligro sísmico para un periodo de retorno de 475 años, reconociendo el comportamiento estructural ante un sismo de gran magnitud.
El presente estudio titulado: Análisis de la amplificación sísmica de edificios del Cercado de Lima – Lima y La Punta – Callao por medio del análisis modal espectral y tiempo – historia mediante acelerogramas sintéticos; cuyo objetivo es realizar la comparación de dichos métodos en 4 edificios (2 de 5 niveles y 2 de 12 niveles) cuya configuración estructural es de muros de concreto armado, los cuales se estudiaran en dos distintos tipos de suelo (Cercado de Lima y La Punta) con la finalidad de obtener resultados de derivas, fuerzas, desplazamientos y aceleraciones para determinar la amplificación sísmica en los suelos mencionados, y así optar por el método de análisis más óptimo.
Asimismo, el propósito del presente estudio es conocer el comportamiento de la edificación acorde con la realidad peruana; es decir edificaciones con periodos cortos; el cual evaluará la vulnerabilidad mediante acelerogramas sintéticos, reconociendo el comportamiento estructural ante una eventualidad sísmica de gran magnitud.Currently, the population of Lima does not have their own and secure homes; For this reason, the boom in the field of massive construction emerges with large multi-family buildings, whose resistance to the telluric impact of enormous magnitude of 8 to 9 degrees continues in seismic testing; therefore, it is very relevant to make the comparison of the analysis of the spectral modal method of the structure (displacements and accelerations with respect to the ground) and an analysis of the time-history method where the maximum deformations of the structure of the buildings will be obtained in this present study. ; Likewise, it will assess the vulnerability of structural construction using synthetic accelerograms using the uniform hazard spectrum obtained in Parque de la Reserva, Cercado de Lima as the objective spectrum, through a seismic hazard study for a return period of 475 years, recognizing structural behavior in the face of a large earthquake. The present study entitled: Analysis of the seismic amplification of buildings in Cercado de Lima - Lima and La Punta - Callao by means of spectral modal analysis and time - history using synthetic accelerograms; the objective of which is to compare these methods in 4 buildings (2 of 5 levels and 2 of 12 levels) whose structural configuration is made of reinforced concrete walls, which will be studied in two different types of soil (Cercado de Lima and La Punta ) in order to obtain results of drifts, forces, displacements and accelerations to determine the seismic amplification in the mentioned soils, and thus opt for the most optimal analysis method. Likewise, the purpose of this study is to know the behavior of the building in accordance with the Peruvian reality; that is to say buildings with short periods; which will assess vulnerability using synthetic accelerograms, recognizing the structural behavior in the event of a large seismic event.
Tesis
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Vincens, Eric. "Estimation des tassements des sols sous séismes." Ecully, Ecole centrale de Lyon, 1999. http://bibli.ec-lyon.fr/exl-doc/TH_T1784_evincens.pdf.
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L'étude des tassements des milieux granulaires sous sollicitation sismique, bien que n'ayant pas retenue l'attention de nombreux chercheurs par le passé, apparaît cruciale si l'on veut garantir la bonne tenue de remblais, digues ou terrains sur lesquels reposent certains ouvrages à risques. Ainsi, notre travail a-t-il d'abord consisté en l'étude de mouvements californiens au rocher, certaines caractéristiques ou généralités ont été dégagées permettant d'envisager une modélisation du mouvemenst sismique par un processus aléatoire défini par sa Densité Spectrale de Puissance. En effet, l'utilisation d'enregistrements réels dans toute étude sismique est restreinte à la représentativité de ces derniers. Il est alors parfois préférable de considérer un mouvement rendant compte de la réalité de manière plus globalisante, ce que nous nous sommes proposé de faire. Les paramètres du modèle de Clough-Penzien, représentation analytique de la Densité Spectrale de Puissance ont été trouvés à l'aide des spectres standards NRC puis AFPS. L'autre étape a abouti au choix d'un modèle simple de densification des sols qui met en avant le rôle prépondérant du cumul du déviateur des déformations. En constatant qu'il était posssible d'approcher de manière convenable la valeur des tassements issus d'un calcul élastique linéaire équivalent, nous avons proposé une formulation analytique simple du tassement. Cette formulation a l'avantage d'éviter tout calcul transitoire mais nécessite néanmoins la connaissance du spectre de réponse (Sa) à 10 % ainsi que la durée de la phase forte du mouvement. Notre approche est celle qui est généralement privilégiée dans le cadre d'un avant-projet parasismique. Enfin, elle nous a permis de proposer un nouveau facteur rendant compte du pouvoir endommageant de tout mouvement sismique aboutissant à une possible classification ou comparaison de ces derniers. Classiquement, il est supposé que seul le mouvement sismique permet de rendre compte de l'endommagement d'un système ; nous pensons qu'il est nécessaire de faire intervenir certaines caractéristiques du système pour atteindre ce butEstimating the settlements of soil profiles is of major interest if one wants to guarantee dam stability or durability of structures in areas subjected to earthquakes. But this point wasn't investigated by recent researchers and needed further developments. First of all, our work consisted in studying Californian accelerograms recorded on bedrock. Some characteristics and properties were drawn so that a modelisation of the seismic movement could be established by a random process. Indeed, deterministic records are linked to problems of representativity. More often, it's better to use an artificial record that accounts for global phenomena, which we intended to do herein. So, an earthquake can be represented by a limited duration segment of a stationary random process. We've chosen the one proposed by Clough-Penzien, the function parameters were found so that the articial time excitation generated be compatible with design response spectra NRC or AFPS. The second part of this work was to propose a simple soil densification law, the one chosen puts forward the major role of the cumulative deformation deviator in the process. An analytical evaluation of settlements was pointed out so that it approaches the results given by an equivalent linear elastic method in a satisfactory way. Our method prevents any transient computation and only needs the computation of the response spectra Sa (10 %) as well as the strong duration of the movement. This analytical formulation of the settlements is a preliminary design solution of the problem, a method commonly used. Then, we proposed a new parameter related to potential damages that can be observed after earthquakes resulting in a possible classification or comparison between accelerograms. Usually, this classification is only performed in studying accelerograms, we pointed out that some characteristics of the system observed must be included to achieve it
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Isbiliroglu, Levent. "Strategy for Selecting Input Ground Motion for Structural Seismic Demand Analysis." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU009/document.
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Les signaux accélérométriques enregistrés lors de l’occurrence d’un événement sismique est très large présentent une forte variabilité, par conséquent ils ne sont pas utilisé dans les analyse dynamiques de tenue sismique des structures. En effet, l’utilisation des accélérogrammes réels, pour les analyses dynamiques non linéaires, s’avère couteuse en termes de temps de calcul. La pratique courante prévoit la minimisation (voir suppression) de telle variabilité, mais les conséquences d’une telle opération sur la réponse des structures ne sont pas clairement indiquées. L’étude ci-présente a pour scope la quantification de l’impact des méthodes de sélection qui gardent la variabilité du signal sur les résultats de l’analyse de la réponse des structures (exprimée en termes d’engineering demand parameters EDPs). En particulier les questions suivantes seront investiguées :Quel est le niveau de variabilité des accélérogrammes réels et comment ce niveau est modifié par les techniques couramment utilisées ?Quelle est l’impact de la variabilité sur la réponse de plusieurs types de structures ?Pour un scénario sismique donné, un spectre cible est défini à partir de plusieurs équation de prédiction du mouvement sismique, sélection parmi celles disponibles en littérature. Les accélérogrammes sont sélectionnés à partir de quatre familles d’accélérogrammes, chacune relative à une méthode de modification : réels (enregistrés); mise à l’échelle (multiplication, par un facteur) ; calés aux spectres cibles avec large tolérance ; calés aux spectres cibles dans une plage de tolérance étroite.Chaque jeu de signaux est composé de cinq accélérogrammes et la sélection des signaux est faite en tenant compte de deux sources de variabilité : la variabilité au sein de chaque jeu de données (intraset), et la variabilité entre les différents jeux de données (interset) tous compatibles avec le même spectre cible. Les tests sur les EDPs menés sur les signaux accélérométriques réels mènent à la quantification de la variabilité naturelle (pour le scénario considéré). Les analyses basées sur les signaux réels sont utilisés comme benchmark afin d’évaluer non seulement de combien la distribution des EDPs (en termes de valeur moyenne et variabilité) est réduite par les différentes méthodes testées, mais aussi d’évaluer l’impact des choix de l’équation de prédiction du mouvement, des plages de tolérance, du nombre d’accélérogrammes constituant chaque jeu, du nombre de jeux, de le scope de l’analyse structurale et le modèle de structure.Ce travaille nous conduit à conclure que un seul jeu d’accélérogramme, tel qu’utilisé dans la pratique courante, est insuffisant pour assurer le niveau d’EDPs indépendamment de la méthode de modification utilisés, cela est lié à la variabilité des signaux et entre les jeux d’accélérogrammes. Les signaux réels, compatibles avec le spectre définis pour le scénario sismique, are l’option plus réaliste pour l’analyse dynamique non-linéaire ; si une méthode de modification du signal est nécessaire, la plus adaptées dépend du scope de l’analyse spectrale et du modèle. Le choix de l’équation de prédiction du mouvement sismique utilisée pour définir le spectre cible impacte significativement les caractéristiques des mouvements sismiques et des EDPs. Cette observation ne dépend pas de la stratégie de de modification du signalThe observed variability is very large among natural earthquake records, which are not consolidated in the engineering applications due to the cost and the duration. In the current practice with the nonlinear dynamic analysis, the input variability is minimized, yet without clear indications of its consequences on the output seismic behavior of structures. The study, herein, aims at quantifying the impact of ground motion selection with large variability on the distribution of engineering demand parameters (EDPs) by investigating the following questions:What is the level of variability in natural and modified ground motions?What is the impact of input variability on the EDPs of various structural types?For a given earthquake scenario, target spectra are defined by ground motion prediction equations (GMPEs). Four ground motion modification and selection methods such as (1) the unscaled earthquake records, (2) the linearly scaled real records, (3) the loosely matched spectrum waveforms, and (4) the tightly matched waveforms are utilized. The tests on the EDPs are performed on a record basis to quantify the natural variability in unscaled earthquake records and the relative changes triggered by the ground motion modifications.Each dataset is composed by five accelerograms; the response spectrum compatible selection is then performed by considering the impact of set variability. The intraset variability relates to the spectral amplitude dispersion in a given set, and the interset variability relates to the existence of multiple sets compatible with the target.The tests on the EDPs are performed on a record basis to quantify the natural variability in unscaled earthquake records and the relative changes triggered by the ground motion modifications. The distributions of EDPs obtained by the modified ground motions are compared to the observed distribution by the unscaled earthquake records as a function of ground motion prediction equations, objective of structural analysis, and structural models.This thesis demonstrates that a single ground motion set, commonly used in the practice, is not sufficient to obtain an assuring level of the EDPs regardless of the GMSM methods, which is due to the record and set variability. The unscaled real records compatible with the scenario are discussed to be the most realistic option to use in the nonlinear dynamic analyses, and the ‘best’ ground motion modification method is demonstrated to be based on the EDP, the objective of the seismic analysis, and the structural model. It is pointed out that the choice of a GMPE can provoke significant differences in the ground motion characteristics and the EDPs, and it can overshadow the differences in the EDPs obtained by the GMSM methods
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Medel, Vera Carlos Pablo. "Seismic probabilistic safety assessment and risk control of nuclear power plants in Northwest Europe." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/seismic-probabilistic-safety-assessment-and-risk-control-of-nuclear-power-plants-in-northwest-europe(c51a155a-289b-40c0-a642-644cb527939b).html.
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Nuclear power plays a crucial role in energy supply in the world: around 15% of the electricity generated worldwide is provided from nuclear stations avoiding around 2.5 billion tonnes of CO2 emissions. As of January 2016, 442 reactors that generated 380+ GW were in operation and 66 new reactors were under construction. The seismic design of new nuclear power plants (NPPs) has gained much interest after the high-profile Fukushima Dai-ichi accident. In the UK, a tectonically stable continental region that possesses medium-to-low seismic activity, strong earthquakes capable of jeopardising the structural integrity of NPPs, although infrequent, can still occur. Despite that no NPP has been built in Great Britain after 1995, a New Build Programme intended to build 16 GW of new nuclear capacity by 2030 is currently under way. This PhD project provides a state-of-the-art framework for seismic probabilistic safety assessment and risk control of NPPs in Northwest Europe with particular application to the British Isles. It includes three progressive levels: (i) seismic input, (ii) seismic risk analysis, and (iii) seismic risk control. For seismic input, a suitable model to rationally define inputs in the context of risk assessments is proposed. Such a model is based on the stochastic simulation of accelerograms that are compatible with seismic scenarios defined by magnitude 4 < Mw < 6.5, epicentral distance 10 km < Repi < 100 km, and different types of soil (rock, stiff soil and soft soil). It was found to be a rational approach that streamlines the simulation of accelerograms to conduct nonlinear dynamic analyses for safety assessments. The model is a function of a few variables customarily known in structural engineering projects. In terms of PGA, PGV and spectral accelerations, the simulated accelerograms were validated by GMPEs calibrated for the UK, Europe and the Middle East, and other stable continental regions. For seismic risk analysis, a straightforward and logical approach to probabilistically assess the risk of NPPs based on the stochastic simulation of accelerograms is studied. It effectively simplifies traditional approaches: for seismic inputs, it avoids the use of selecting/scaling procedures and GMPEs; for structural outputs, it does not use Monte Carlo algorithms to simulate the damage state. However, it demands more expensive computational resources as a large number of nonlinear dynamic analyses are needed. For seismic risk control, strategies to control the risk using seismic protection systems are analysed. This is based on recent experience reported elsewhere of seismically protected nuclear reactor buildings in other areas of medium-to-low seismic activity. Finally, a scenario-based incremental dynamic analysis (IDA) is proposed aimed at the generation of surfaces for unacceptable performance of NPPs as function of earthquake magnitude and distance. It was found that viscous-based devices are more efficient than hysteretic-based devices in controlling the seismic risk of NPPs in the UK. Finally, using the proposed scenario-based IDA, it was found that when considering all controlling scenarios for a representative UK nuclear site, the risk is significantly reduced ranging from 3 to 5 orders of magnitude when using viscous-based devices.
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Navrátilová, Martina. "Nelineární dynamická analýza konstrukce zatížena seismickými účinky." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227701.
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Diploma thesis compares the methods for the calculation of the response of structures with seismic loads. Linear and nonlinear analyses are used for the calculations. In the case of linear analysis response spectrum method is applied. For nonlinear analysis pushover method is used. These two methods are compared in programs AxisVM and RFEM on the examples of high-rise building and space frame.
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Šulerová, Zdeňka. "Dynamická analýza konstrukce zatížená seismickým zatížením." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226647.
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This thesis deals with the calculation of response of reinforced concrete construction on the effect of seismic tension. Time and spectral analysis were made. They are mentioned as possible ways of calculation in EN 1998 - 1:2004 norm. Final figures of global deformations and stress on selected beam from the time and spectral analysis were firstly compared for the horizontal components of seismic stress affecting only in one direction. Subsequently comparison of time progress to combination of these effects mentioned in relevant norm was made. In the conclusion the results of used analysis are appraised.
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Havlíková, Ivana. "Dynamická analýza konstrukce zatížené seismickým zatížením." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225730.
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The purpose of my master’s thesis is the solution steel hall with concrete columns, that is loaded by an earthquake. This simulation program was used RFEM. To calculate was used the spectral and temporal analysis, and that on models of structures with several combinations of materials. The analysis was performed for both the general direction of the earthquake, so for combinations of directions according to standard procedures in EC8.
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Honoré-Foundotos, Laëtitia. "Génération d'accélérogrammes synthétiques large-bande : contribution à l’estimation de l’aléa sismique par validation d’approches en aveugle." Thesis, Nice, 2013. http://www.theses.fr/2013NICE4054/document.
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L’une des problématique scientifique majeure en sismologie est de pouvoir estimer les mouvements du sol attendus en un site pour un futur séisme. L’objectif de cette thèse est de tester et de valider deux méthodes de simulation des mouvements du sol basées sur l’approche des fonctions de Green empiriques et d’apporter des éléments pouvant aider au développement d’une méthodologie de simulation en aveugle. Dans une première partie, une méthode de simulation basée sur une approche stochastique en point-source est validée sur les données réelles de séismes récents bien instrumentés : le séisme des Saintes Mw6.4 et le séisme de L’Aquila Mw6.3. Nous avons développé une approche de simulation en aveugle en prenant en compte une incertitude sur le paramètre de rapport des chutes de contrainte C. Cette approche permet de générer un ensemble d’accélérogrammes synthétiques d’un séisme cible suffisamment variés pour être représentatifs d’un grand nombre de scénarios de sources possibles et prenant en compte dans un sens statistique de potentiels effets de directivité. Cette approche a également été appliquée à la simulation d’un séisme historique pyrénéen Mw6.1. Dans une seconde partie, nous nous appuyons sur un modèle de source étendue plus complexe, combinant des modèles cinématiques de sources composites fractales avec l’approche des FGEs. Le potentiel de la méthode est testé sur une application au séisme de L’Aquila. Cela a permis de produire des résultats très satisfaisants sur l’ensemble des paramètres des mouvements du sol analysés. Cette méthode de simulation apparaît comme étant très prometteuse pour la mise en œuvre d’une méthodologie de simulation en aveugle, même si la principale difficulté réside dans la nécessité de définir la variabilité de nombreux paramètres d’entrée mal connus dans le cadre de la simulation d’un futur séismeOne of the major scientific problems in seismology is to estimate the ground motions expected at a given site from a future earthquake. The aim of this thesis is to test and validate two different methods of ground motions simulation based on the empirical Green’s function approach and to provide elements that can help to develop a blind simulation methodology. In a first part, a simulation method based on a stochastic point source approach is validated on the real data of recent earthquakes well instrumented : the Les Saintes earthquake Mw6.4 and the L’Aquila earthquake Mw6.3. We have developed a blind simulation approach by taking into account an uncertainty on the parameter of stress drop ratio C. This approach allows to generate a set of synthetic accelerograms of a target earthquake varied enough to be representative of a large number of possible source scenario and taking into account in a statistical sense potential directivity effects. This approach is also applied to the simulation of an historical Pyrenean earthquake Mw6.1. In a second part, we use a more complex extended source model, combining kinematic models of fractal composite sources with EGF approach. The potential of the method is tested on an application to L’Aquila earthquake. This has produced very satisfying results on all ground motion parameters analyzed. This simulation method appears to be very promising for the implementation of a blind simulation methodology, even if the main difficulty lies in the need to define the variability of many poorly known input parameters in the simulation of a future earthquake
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Coronel, Huanca Dennys Luis, and Rojas Marcos Visney Mamani. "Respuesta sísmica de estructuras de concreto armado con un análisis tiempo historia no lineal usando acelerogramas artificiales." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/654933.
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La escasez de registros sísmicos de gran magnitud en algunas regiones del mundo limita la determinación de la respuesta sísmica de una edificación. En este sentido, los acelerogramas artificiales representan una alternativa para definir el evento sísmico porque consideran las condiciones específicas del sitio en estudio. Esta investigación analiza la respuesta sísmica de las estructuras para diversos registros sísmicos artificiales generados de espectros de diseño para distintas condiciones geotécnicas. El procedimiento de análisis empleado será el dinámico tiempo historia no lineal para obtener una mayor precisión en la respuesta sísmica. Los resultados obtenidos muestran que las derivas de entrepiso de las señales artificiales creadas con la función de intensidad de Liu se ajustan mejor a las derivas obtenidas del sismo real escalado.The lack of large seismic records in some world regions limits the determination of the seismic response of a building. For that reason, artificial accelerograms represent an alternative to define the seismic event because they consider specific conditions of study site. This research analyses the structures seismic response for various artificial seismic records generated from design spectra and different geotechnical conditions. Dynamic nonlinear time history analyzing was used to obtain greater precision in the seismic response. The results obtained show that the mezzanine drifts of the artificial signals created with the Liu intensity function better fit the drifts obtained from the scaled real earthquake.
Trabajo de investigación
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Čada, Zdeněk. "Vliv technické a přírodní seizmicity na stavební konstrukce se zaměřením na konstrukce ze zdicích materiálů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-233808.
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The dissertation deals with selected issues in the field of the calculation of the response of building structures which are excited with dynamic non-stationary displacement loading of its ground. Seismic load has been assumed. Procedures, how to work with seismic records with respect to the accuracy of dynamic calculations, how to modify the response spectrum to ensure the reliability, how to generate synthetic accelerogram requiring more accurate response, are recommended. Synthetic akcelerogram has been generated by own approaching, which has been used as the excitation function in the experimental seismic testing of autoclaved concrete brick building in model scale. Response values of motion in the measured points of the experiment were compared with the linear and nonlinear dynamic calculations by using the finite element method models. Different levels of detail of the numerical models have been used. The shear wall behaviour has been modelled by using constitutive models with brittle failure as well as using of non-linear interaction interface with possible delamination between the masonry bricks. The behaviour of the mathematical model of wall systems has been calibrated with respect to the measured data at shear wall experiments in real and model scale of walls.
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Marconi, Enrico. "Influenza dell'orditura delle travi nella risposta sismica di strutture a telaio." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Nella presente trattazione vengono presentati i risultati ottenuti da analisi sulle proprietà dinamiche e sulla risposta sismica di strutture in c.a. intelaiate con travi principali ordite in modo differente ai vari livelli di piano.
Dopo alcune considerazioni iniziali sulle problematiche della valutazione della sicurezza strutturale e di conseguenza della riduzione della vulnerabilità sismica degli edifici esistenti,si è proceduto alla descrizione della struttura di riferimento, all'analisi dei carichi ed alla progettazione statica.
Si è quindi passati alla descrizione dei modelli considerati nello studio; essi sono 7 e si differenziano per la disposizione delle travi ai vari piani.
Solamente nel perimetro della struttura, sui lati ortogonali alle travi, sono disposti cordoli.
L'analisi modale è stata condotta ricavando i periodi propri di vibrazione nelle tre direzioni X,Y,ϑ per i modi di vibrare dei modelli considerati; in particolare i periodi del primo modo di vibrare sono stati riportati in un istogramma in funzione dei modelli studiati.
Lo studio della risposta sismica è stato ricavato mediante analisi sismica con spettro di risposta e analisi sismica con accelerogrammi di tipo lineare dinamica.
Dal confronto dei risultati dei due diversi tipi di analisi si osserva che la diversa disposizione delle travi principali ai vari livelli di un edificio con struttura intelaiata in c.a. determina negli elementi verticali resistenti sollecitazioni e spostamenti caratterizzati da una certa variabilità.
La conoscenza dei comportamenti non è solo utile quando si deve affrontare il tema della valutazione degli edifici esistenti, ma anche quando si devono progettare nuove costruzioni.
Dallo studio emerge che le strutture con orditura delle travi alternata ad ogni piano hanno un comportamento molto simile a quello delle strutture 3D, uniforme nelle due direzioni ortogonali, quindi si può affermare che, a conti fatti, non sono così sbagliate le soluzioni alternate singole.
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Levine, Marie-Bernard P. "Accelerogram processing using reliability bounds and optimal correction methods." Thesis, 1990. https://thesis.library.caltech.edu/8127/1/levine-mbp-1990.pdf.
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This study addresses the problem of obtaining reliable velocities and displacements from accelerograms, a concern which often arises in earthquake engineering. A closed-form acceleration expression with random parameters is developed to test any strong-motion accelerogram processing method. Integration of this analytical time history yields the exact velocities, displacements and Fourier spectra. Noise and truncation can also be added. A two-step testing procedure is proposed and the original Volume II routine is used as an illustration. The main sources of error are identified and discussed. Although these errors may be reduced, it is impossible to extract the true time histories from an analog or digital accelerogram because of the uncertain noise level and missing data. Based on these uncertainties, a probabilistic approach is proposed as a new accelerogram processing method. A most probable record is presented as well as a reliability interval which reflects the level of error-uncertainty introduced by the recording and digitization process. The data is processed in the frequency domain, under assumptions governing either the initial value or the temporal mean of the time histories. This new processing approach is tested on synthetic records. It induces little error and the digitization noise is adequately bounded. Filtering is intended to be kept to a minimum and two optimal error-reduction methods are proposed. The "noise filters" reduce the noise level at each harmonic of the spectrum as a function of the signal-to-noise ratio. However, the correction at low frequencies is not sufficient to significantly reduce the drifts in the integrated time histories. The "spectral substitution method" uses optimization techniques to fit spectral models of near-field, far-field or structural motions to the amplitude spectrum of the measured data. The extremes of the spectrum of the recorded data where noise and error prevail are then partly altered, but not removed, and statistical criteria provide the choice of the appropriate cutoff frequencies. This correction method has been applied to existing strong-motion far-field, near-field and structural data with promising results. Since this correction method maintains the whole frequency range of the record, it should prove to be very useful in studying the long-period dynamics of local geology and structures.
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JEN, WAN-SHAN, and 任萬山. "The Analysis of Accelerograms of the Chung-Yang Highway Bridge." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/15388779140442869435.
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Giaralis, Agathoklis. "Wavelet based response spectrum compatible synthesis of accelerograms and statistical linearization based analysis of the peak response of inelastic systems." Thesis, 2008. http://hdl.handle.net/1911/22225.
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A novel method for producing seismic accelerograms whose response spectra comply with the pertinent seismic code criteria has been proposed. It encompasses a stochastic dynamics formulation for defining an evolutionary power spectrum that is related to a given design (target) spectrum in a statistical sense, and a deterministic harmonic wavelet-based procedure to iteratively modify seismic accelerograms on an individual basis. The incorporation of the stochastic dynamics formulation allows for generating ensembles of artificial design spectrum compatible accelerograms, without the need to consider any recorded strong ground motion. Several such ensembles pertaining to the design spectrum prescribed by the European aseismic code provisions (EC8) are provided.
Moreover, in the developed wavelet-based procedure the unique attributes of harmonic wavelets are exploited to "surgically" modify the frequency content of seismic accelerograms to meet the commonly prescribed compatibility criteria. An example involving the modification of a suite of real recorded accelerograms to be used for the design of base-isolated buildings according to the EC8 code provisions is included. Appropriate wavelet-based joint time-frequency analysis of the original and of the modified signals have been provided suggesting that the modified signals maintain the main patterns of the evolutionary frequency content of the original accelerograms.
Appended to the above a computationally efficient methodology is suggested for estimating the maximum seismic response of nonlinear systems exposed to excitations specified by a given design spectrum. Specifically, stationary design spectrum compatible power spectra are considered in conjunction with the method of statistical linearization to derive effective linear stiffness and damping properties associated with certain nonlinear oscillators. The cases of Duffing bilinear hysteretic, and smooth hysteretic systems described by the Bouc-Wen differential model are considered. It is found via pertinent Monte Carlo analyses that the peak response of the nonlinear and of the derived equivalent linear systems compare reasonably well. Furthermore, it is shown through appropriate numerical examples that the latter methodology is capable of deriving inelastic response spectra from elastic design spectra without the need to integrate numerically the underlying nonlinear equations of motion.
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Raghu, Kanth S. T. G. "Engineering Seismic Source Models And Strong Ground Motion." Thesis, 2005. http://etd.iisc.ernet.in/handle/2005/1491.
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