Tesis sobre el tema "Nonlinear Structural Dynamic"
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Izzuddin, Bassam Afif. "Nonlinear dynamic analysis of framed structures". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/8080.
Texto completoYan, Zhihao y 阎志浩. "Nonlinear dynamic analysis and strcutural identification of frames". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43224076.
Texto completoYan, Zhihao. "Nonlinear dynamic analysis and strcutural identification of frames". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43224076.
Texto completoNormann, James Brian. "Parametric identification of nonlinear structural dynamic systems". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43294.
Texto completoMaster of Science
Kapoor, Hitesh. "Nonlinear Dynamic Response of Flexible Membrane Structures to Blast Loads". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/41238.
Texto completoMaster of Science
Ashmawy, Mahmoud El Hassan Aly. "Nonlinear dynamic analysis of guyed masts for wind and earthquake loading". Thesis, University of Westminster, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304725.
Texto completoBenamar, Rhali. "Nonlinear dynamic behaviour of fully clamped beams and rectangular isotropic and laminated plates". Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280910.
Texto completoYao, Ming-Sheng. "Linear and geometrically nonlinear structural dynamic analysis using reduced basis finite element technique". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46620.
Texto completoBadmus, Olanrewju O. "Nonlinear dynamic analysis and control of surge and rotating stall in axial compression systems". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/11296.
Texto completoKoko, Tamunoiyala Stanley. "Super finite elements for nonlinear static and dynamic analysis of stiffened plate structures". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30723.
Texto completoApplied Science, Faculty of
Civil Engineering, Department of
Graduate
Sotoudeh, Zahra. "Nonlinear static and dynamic analysis of beam structures using fully intrinsic equations". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41179.
Texto completoAkpinar, Ugur. "Nonlinear Analysis Of Rc Frames Retrofitted With Structural Steel Elements". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612380/index.pdf.
Texto completoand evaluate their seismic performances. First, analytical models of the frames with braces and internal steel frames were prepared and then their responses were compared with cyclic responses of experimental studies. Results of these models were used to determine performance limits by the methods proposed by TEC2007 and ASCE/SEI-41. Then, calibrated models were employed for time history analyses with various scales of Duzce ground motion and analytical results were compared with experimental findings. Seismic performance of these systems was also evaluated by using aforementioned codes. Finally, evaluated retrofitting schemes were applied to a 4-story 3-bay reinforced concrete frame that was obtained from an existing deficient structure and effectiveness of applied retrofitting schemes was investigated in detail.
Hardyniec, Andrew B. "An Investigation of the Behavior of Structural Systems with Modeling Uncertainties". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/56635.
Texto completoPh. D.
Aykan, Murat. "Identification Of Localized Nonlinearity For Dynamic Analysis Of Structures". Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615596/index.pdf.
Texto completoHiwarkar, Vikrant. "Nonlinear dynamics of cracked structures for non-destructive evaluation". Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6712.
Texto completoRank, Aaron. "A novel experimental approach using a reconfigurable test setup for complex nonlinear dynamic systems". Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5014.
Texto completoID: 030423494; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 132-137).
M.S.
Masters
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Paul, Bryan. "Analytical And Experimental Study Of Monitoring For Chain-Like Nonlinear Dynamic Systems". Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5686.
Texto completoM.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering; Structures and Geotechnical Engineering
Lülf, Fritz Adrian. "An integrated method for the transient solution of reduced order models of geometrically nonlinear structural dynamic systems". Phd thesis, Conservatoire national des arts et metiers - CNAM, 2013. http://tel.archives-ouvertes.fr/tel-00957455.
Texto completoGoodpaster, Benjamin A. "Analytical Modeling and Impedance Characterization of Nonlinear, Steady-State Structural Dynamics in Thermomechanical Loading Environments". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524063139635613.
Texto completoSarego, Giulia. "Structural material damage: novel methods of analysis". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3427223.
Texto completoNella teoria classica della meccanica dei solidi, la formulazione matematica include derivate parziali, grazie alle quali si possono rappresentare stati di deformazione come funzioni degli spostamenti relativi dei nodi in cui è discretizzato il sistema continuo. Una carenza rilevante dovuto all’utilizzo delle derivate è legato ai risultati privi di significato fisico ottenuti in prossimità delle discontinuità perché le derivate non sono definite laddove manca un campo di spostamenti continuo, come può capitare in presenza di dislocazioni, vuoti, cricche, interfacce tra fasi differenti nello stesso corpo e bordi dei grani. Dato che la formazione spontanea e la crescita di discontinuità sono di grande importanza in meccanica dei solidi, diverse tecniche sono state utilizzate per superare questa incapacità della teoria di descrivere il comportamento dei materiali in tali condizioni, perché situazioni in cui le strutture sono incapaci di continuare a svolgere la propria funzione devono essere evitate, specialmente per strutture aerospaziali, in primo luogo, per ragioni di sicurezza ed, in secondo luogo, per motivi economici. Uno di questi nuovi approcci riguarda l’utilizzo di teorie non locali basate su formulazioni integrali (più precisamente formulazioni integro-differenziali), definite anche quando campi di spostamento non derivabili sono presenti. La teoria “Peridynamics” è una di queste teorie: è stata proposta da Stewart Silling nel 2000 [1] così da adottare una formulazione unica e coerente capace di descrivere i comportamenti dei materiali in corpi sia continui che discontinui, evitando l’uso di equazioni alle derivate parziali o la definizione a priori di alcune condizioni che possono influenzare (e in un certo senso favorire) dei risultati. Ci sono due versioni di modelli peridinamici: la state-based, e un suo caso particolare, la bond-based, che è stata introdotta per prima (vedi [1, 2]). Nella versione bond-based, le forze tra due punti materiali dependono unicamente dal loro spostamento relativo e dalla loro posizione relativa iniziale, oltre che dalle proprietà del materiale. Vista la sua semplicità a confronto con la seconda versione, la maggior parte delle applicazioni e degli articoli sulla Peridynamica ha adottato la formulazione bond-based. Tuttavia, i modelli nella formulazione bond-based sono caratterizzati da alcune limitazioni (le stesse dei modelli di altre teorie atomistiche e dei modelli di dinamica molecolare [3], anche se la Peridinamica è una teoria del continuo, non discreta), la più notevole di queste è il modulo di Poisson fisso: 1/4 nelle simulazioni 3D oppure in caso di deformazione piana 2D, e 1/3 nelle simulazioni in stato di tensione piana 2D (si veda per esempio [1, 4]). Questa particolarità implica altre restrizioni, come l’impossibilità di riprodurre la condizione di incomprimibilità plastica in maniera accurata. Tuttavia, per la maggior parte degli scopi, la formulazione bond-based è sufficiente e fornisce risultati approssimati soddisfacenti. I modelli della versione state-based rimuovono queste restrizioni, permettendo che le interazioni tra due punti possano dipendere da tutte le interazioni (i “bond”) connessi ad almeno uno dei due punti, tramite delle mappe avanzate chiamate “states”. Inoltre, ci sono due tipi di formulazioni state-based: la ordinary e la non-ordinary [2, 5, 6]. Nella formulazione ordinary, le forze tra due punti materiali agiscono lungo la congiungente i due punti nella configurazione deformata, mentre nella formulazione non-ordinary, questa caratteristica non è più vera. La formulazione ordinary della state-based necessita di modelli costitutivi appositamente derivati, come per esempio i modelli di viscoelasticità e platicità in [7, 8]. Per la formulazione non-ordinary della state-based, due approcci sono stati proposti: lo sviluppo di un modello esplicito per l’espressione dello state della forza peridinamica [2] e lo sviluppo di una mappa grazie alla quale le relazioni costitutive della meccanica classica sono incorporate per stabilire indirettamente la relazione tra la forza d’interazione e la deformazione. I modelli derivanti dal secondo approccio sono chiamati modelli correspondence [2]. L’argomento di questa tesi è lo sviluppo di modelli per particolari tipi di analisi e la ricerca di possibili vantaggi e inconvenienti di questa teoria nuova ed inesplorata, così da identificare alcune linee guida per la scelta di parametri fondamentali per le analisi. Durante il primo anno del corso di dottorato, lo stato dell’arte relativo a questa teoria è stato studiato e i solutori statici lineari e non lineari nella formulazione bond-based sviluppati precedentemente in ambiente Matlabr sono stati analizzati, usati e migliorati. Durante il secondo anno, l’autrice di questa tesi si è concentrata sulla seconda versione, basata su concetti di matematica avanzata con cui ha preso dimestichezza grazie al corso di analisi funzionale seguito il primo anno. Uno dei principali contributi originali alla letteratura esistente presenti in questa tesi è lo sviluppo dei modelli linearizzati 2D del modello solido lineare nella formulazione state-based. Questi modelli sono particolarmente utili quando semplificazioni di stato piano di tensione o di deformazione possono essere assunte per la simulazione di un sistema tridimensionale, che altrimenti verrebbe descritto da un modello 3D che necessiterebbe di risorse computazionali più elevate (in termini di tempo e memoria). Una particolare attenzione è richiesta per quest’aspetto, perché, essendo un approccio non locale, implementare un codice basato sulla teoria peridinamica richiede in generale più risorse computazionali di un codice basato su un approccio locale. Lo studio della versione state-based è iniziato prima di andare all’estero e lo sviluppo dei modelli 2D si è poi completato durante il soggiorno di sei mesi alla University of Nebraska-Lincoln negli Stati Uniti. Sono stati sviluppati sia un codice dinamico che uno statico. I parametri principali di questi modelli sono stati analizzati e i modelli linearizzati si possono trovare descritti nel capitolo 1.2.2. Lo studio dei criteri di frattura adottabili nella formulazione state-based e il miglioramento degli algoritmi in Matlabr per accelerare i codici e ottimizzare le risorse di memoria e gestione dei dati sono stati gli argomenti principali del terzo anno. Alcuni criteri di frattura, presentati nel capitolo 1.2.3, sono stati proposti per materiali lineari elastici omogenei e caratterizzati da frattura fragile. Sono criteri basati sul massimo allungamento: un’interazione non locale (“bond”) viene meno quando un valore critico di allungamento è raggiunto; questo valore di allungamento critico è calcolato dal lavoro richiesto per rompere il bond e questo lavoro è a sua volta legato all’energia di frattura. I risultati ottenuti sono stati confrontati con dati sperimentali per casi sia statici che dinamici, sia nella formulazione bondbased che in quella state-based. La descrizione dettagliata degli algoritmi si trova nel capitolo 3, mentre i risultati sono riportati nei capitoli 4 e 5.
Vedernikov, Ivan. "Seismic analysis of the roofing structural system of Adana stadium in Adana, Turkey". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Buscar texto completoKim, Hee Sun. "Nonlinear multi-scale anisotropic material and structural models for prosthetic and native aortic heart valves". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29671.
Texto completoCommittee Chair: Haj-Ali, Rami; Committee Member: White, Donald; Committee Member: Will, Kenneth; Committee Member: Yavari, Arash; Committee Member: Yoganathan, Ajit. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Degirmenci, Can. "Dynamic Pull Analysis For Estimating The Seismic Response". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607833/index.pdf.
Texto completoDynamic Pull Analysis&rdquo
for estimating the seismic response of multi degree of freedom (MDOF) systems. The method is tested on a six-story reinforced concrete frame and a twelve-story reinforced concrete frame that are designed according to the regulations of TS-500 (2000) and TEC (1997).
Spears, Paul Wesley. "Parameters Influencing Seismic Structural Collapse with Emphasis on Vertical Accelerations and the Possible Related Risks for New and Existing Structures in the Central and Eastern United States". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/42793.
Texto completoFrom the parameter study, it was found that the post-yield stiffness ratio augmented by P-Delta effects (rp) in conjunction with the ductility demand was the best predictor of collapse. These two quantities include all four structural parameters and the seismic displacement demands. It was also discovered in the parameter study that vertical accelerations did not significantly influence lateral displacements unless a given combination of model and earthquake parameters was altered such that the model was on the verge of collapsing.
The second study involved Incremental Dynamic Analysis (IDA) using bilinear SDOF models representative of low rise buildings in both the Western United States (WUS) and the Central and Eastern United States (CEUS). Models were created that represented three, five, seven, and nine story buildings. Five sites from both the WUS and CEUS were used. Four different damage measures were used to assess the performance of the buildings. The IDA study was primarily interested in the response of the structures between the earthquake intensities that have a 10 percent probability of occurring in 50 years (10/50) and 2 percent probability of occurring in 50 years (2/50).
The results showed that all structures could be in danger of severe damage and possible collapse, depending on which damage measure and which earthquake was used. It is important to note, though, that the aforementioned is based on a damage-based collapse rule. The damage-based rule results were highly variable.
Using an intensity-based collapse rule, proved to be more consistent. Due to the nature of the bilinear models, only those structures with negative rp values ever collapsed using an intensity-based collapse rule. Most of the WUS models had positive rp values and many of the CEUS models had negative rp values. While many of the CEUS structures had negative rp values, which made them prone to collapse, most of the CEUS structures analyzed did not collapse at the 2/50 intensity. The reason was that the periods of the CEUS models were much longer than the approximate periods that were required to determine the strengths. Consequently, the strength capacity of most of the CEUS models was much greater than the seismic strength demands. While many of the CEUS models did have sudden collapses due to the large negative rp values, the collapses happened at intensities that were generally much higher than the 2/50 event.
In the IDA, it was also shown that vertical accelerations can significantly affect the ductility demands of a model with a negative rp post-yield stiffness ratio as the earthquake intensity approaches the collapse intensity. Since IDA is concerned with establishing collapse limit states, it seems that the most accurate collapse assessments would include vertical accelerations.
Master of Science
Jiang, Xiaomo. "Dynamic fuzzy wavelet neural network for system identification, damage detection and active control of highrise buildings". Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1110266591.
Texto completoTitle from first page of PDF file. Document formatted into pages; contains xvii, 221 p.; also includes graphics (some col.). Includes bibliographical references (p. 210-221). Available online via OhioLINK's ETD Center
Hur, Jieun. "Seismic performance evaluation of switchboard cabinets using nonlinear numerical models". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45813.
Texto completoMuraleedharan, Atmaram. "Fatigue design and dynamic analysis of Steel catenary risers at Touch down zone with nonlinear soil structure interaction model under randomly generated waves". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Buscar texto completoOzcelik, Ramazan. "Seismic Upgrading Of Reinforced Concrete Frames With Structural Steel Elements". Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613450/index.pdf.
Texto completoscaled three bay-two story frame specimens strengthened with chevron brace and ISF were tested by employing continuous pseudo dynamic testing methods. The test results indicated that the cyclic performance of the Xbrace and column with shear plate assemblage technique were unsatisfactory. On the other hand, both chevron brace and ISF had acceptable cyclic performance and these two techniques were found to be candidate solutions for seismic retrofitting of deficient RC structures. The numerical simulations by conducting nonlinear static and dynamic analysis were used to estimate performance limits of the RC frame and steel members. Suggested strengthening approaches, chevron brace and ISF, were also employed to an existing five story case study RC building to demonstrate the performance efficiency. Finally, design approaches by using existing strengthening guidelines in Turkish Earthquake Code and ASCE/SEI 41 (2007) documents were suggested.
Huang, Xingrong. "Optimization of dynamic behavior of assembled structures based on generalized modal synthesis". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC038/document.
Texto completoNoise and vibration are important topics in the automotive industry for several reasons, including passenger comfort and structural integrity. The main objective of this thesis is to propose a series of appropriate methods to optimize structural system characteristics, so that the vibration and noise can be reduced. To achieve this goal, interface control strategies are employed, including bonding viscoelastic layers onto the most heavily deformed zones and introducing frictional damping devices calibrated on certain resonance frequencies. Such built-up structural systems are numerically investigated via a generalized modal synthesis approach that incorporates several groups of modes. The employed modal synthesis approach consists of several levels of condensation. The first one is on the internal degrees of freedoms (DOFs) of each substructure, and the second condensation is on the branch modes so as to reduce the boundary DOFs among substructures. For coupled fluid-structural systems, a third condensation on the fluid DOFs is suggested. With these condensation techniques, the system dimension can be significantly reduced. The method allows us to obtain the forced response of the structures as well as the pressure variation of the fluids. Additionally, modal parameters characterizing vibration and noise transmission paths can be deduced as mid-stage results. We show that these modal parameters can be used as optimization objective during the interface configuration design. The Pareto front of the optimal design is achieved by employing Kriging approximations followed with an elitist multi-objective genetic algorithm. Another advantage of the modal approach is that a modal overview on the system characteristics is provided by analyzing the natural frequencies, modal damping ratios and the aforementioned modal parameters. The modal synthesis approach is further extended to study nonlinear systems. The basic assumption is that the nonlinear modes are weakly coupled. Nonlinear modal parameters, such as modal frequency and modal damping ratio, contain the essential nonlinear information and depend on modal amplitude. The main idea is to compute nonlinear normal modes according to their modal amplitude and superimpose the response of several nonlinear modes to obtain the overall forced response. The method is applied to systems involving Duffing and dry friction nonlinearities. In the case of dry friction, a generalized Masing model is considered to capture the dry friction nature. Both complex modes and real modes are used in the modal synthesis, leading to different frictional damping terms. We show that the nonlinear modal synthesis combined with the generalized Masing model yields a simple, fast and efficient numerical method to describe nonlinear performance of structures with dry friction
Mohammadi, Alireza. "Wind Performance Based Design for High-Rise Buildings". FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/3032.
Texto completoJudd, Johnn P. "Multi-hazard performance of steel moment frame buildings with collapse prevention systems in the central and eastern United States". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73509.
Texto completoPh. D.
Astorga, Nino Ariana. "Surveillance sismique des structures : caractérisation de la réponse des bâtiments en analysant l'élasticité non linéaire et la dynamique lente". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU021/document.
Texto completoMonitoring structural response is fundamental for evaluating the performance of buildings and reducing losses during future earthquakes. One practical way to detect changes in structural behavior is analyzing variations of elastic properties during dynamic excitations. Here we show that variations in the fundamental frequency of buildings during (weak -to- strong) earthquakes might be explained by nonlinear elastic processes carried out within the structural material, which affect the global macroscopic structural behavior. These nonlinear elastic processes are responsible for both transitory and permanent structural softening, and might explain the intriguing recovery effects observed in the fundamental frequency of buildings following seismic events. This study bridges the gap between microscale laboratory experiments and macroscale seismological observations, where nonlinear elasticity is also observed. In the first part of this study, a new seismic database of building responses is presented: thousands strong motion recordings and several buildings from Japan and US were processed, providing useful tools for the earthquake engineering community, notably for the empirical prediction of structural response as a function of several ground motion intensity measures. Examples of uncertainties associated to damage prediction are presented, as well as the vulnerability assessment of a building throughout fragility curves. Next, the seismic database is used to analyze nonlinear elastic signatures in buildings, particularly the slow dynamics or relaxation effects. Variations of resonant frequencies are monitored at both short and long-term, estimating the contribution of soil in the response of the system soil-structure. Different levels of damage are inferred according to loading amplitudes and structural states. Some laboratory-based models of relaxation are adapted to the building data in order to infer crack-density and heterogeneities over time, making comparisons between structural states before and after large excitations such as the Mw 9 Tohoku earthquake. Conditioning effects are observed during the backbone recovery of aftershocks sequences. The results are extended to different building typologies, analyzing the influence of structural material and loading features, notably strain-rates. Finally, some general conclusions are presented, together with a perspective work using machine learning to predict building response based on nonlinear elastic signatures
Ramanathan, Suresh. "Dynamics characterization of highly flexible beams using a 3D motion analysis system /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426096.
Texto completoGhadimi, R. "Nonlinear dynamic analysis of offshore structures". Thesis, Cranfield University, 1986. http://hdl.handle.net/1826/3581.
Texto completoZhang, Jin. "Identification of nonlinear structural dynamical system". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/12270.
Texto completoBeaver, Stefanie Rene'. "Input-ouput approximation for nonlinear structural dynamics". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1398.
Texto completoGu, Jiaping. "Nonlinear dynamic analysis of large scale structures". Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/63829.
Texto completoLiu, Guang Ning. "Vulnerability and integrity of nonlinear dynamic structures". Thesis, University of Bristol, 2008. http://hdl.handle.net/1983/d7fbdebe-8885-4d4f-adca-bd40e9c7c3b2.
Texto completoPetviachvili, Nikolai. "Coherent structures in nonlinear plasma dynamics /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Texto completoAbhyankar, N. S. "Studies in nonlinear structural dynamics: chaotic behavior and poynting effect". Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/12523.
Texto completoEiras, Fernández Jesús Nuño. "Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability". Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/71439.
Texto completo[ES] El ensayo de determinación de las frecuencias de resonancia ha sido tradicionalmente empleado para determinar la integridad mecánica de testigos de hormigón, en la evaluación de la conformidad de mezclas de hormigón en diversos ensayos de durabilidad, y en la terminación de propiedades constitutivas como son el módulo elástico y el factor de amortiguamiento. Esta técnica no destructiva ha sido ampliamente apelada para la evaluación de las propiedades mecánicas en todo tipo de ensayos de durabilidad. La evolución del daño es comúnmente evaluada a partir de la reducción del módulo dinámico, producido como resultado de cualquier proceso de fisuración. Sin embargo, el comportamiento mecánico del hormigón es intrínsecamente no lineal y presenta histéresis. Como resultado de un comportamiento tensión-deformación con histéresis, el módulo elástico depende de la deformación. En ensayos dinámicos, la no linealidad del material se manifiesta por una disminución de las frecuencias de resonancia, la cual es inversamente proporcional a la amplitud de excitación. Este fenómeno es normalmente denominado como dinámica rápida. Una vez la excitación cesa, el material experimenta un proceso de relajación por el cual, el módulo elástico es restaurado a aquel en situación de reposo. Este fenómeno es denominado como dinámica lenta. Estos fenómenos ¿dinámicas rápida y lenta¿ encuentran su origen en la fricción interna del material. Por tanto, en materiales basados en cemento, la presencia de microfisuras y las interfaces entre sus constituyentes juegan un rol importante en la no linealidad mecánica del material. En el contexto de evaluación de la durabilidad del hormigón, la evolución del daño está basada en el incremento de histéresis, como resultado de cualquier proceso de fisuración. En esta tesis se investigan tres técnicas diferentes las cuales utilizan el impacto como medio de excitación de las frecuencias de resonancia. La primera técnica consiste en determinar las frecuencias de resonancia a diferentes energías de impacto. La técnica es denominada en inglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Ésta consiste en relacionar el detrimento que el material experimenta en sus frecuencias de resonancia, con el aumento de la amplitud de la excitación. La segunda técnica consiste en investigar el comportamiento no lineal mediante el análisis de la señal correspondiente a un solo impacto. Ésta consiste en determinar las propiedades instantáneas de frecuencia, atenuación y amplitud. Esta técnica se denomina, en inglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Se proponen dos técnicas de extracción del comportamiento no lineal mediante el análisis de las variaciones instantáneas de frecuencia y atenuación. La primera técnica consiste en la discretización de la variación de la frecuencia con el tiempo, mediante un análisis basado en Short-Time Fourier Transform (STFT). La segunda técnica consiste en un ajuste por mínimos cuadrados de las señales de vibración a un modelo que considera las variaciones de frecuencia y atenuación con el tiempo. La tercera técnica empleada en esta tesis puede ser empleada para la evaluación de estructuras in situ. La técnica se trata de un ensayo acusto-elástico en régimen dinámico. En inglés Dynamic Acousto-Elastic Test (DAET). Las variaciones del módulo elástico obtenidas mediante los métodos NIRAS y NSIRAS proporcionan un comportamiento promedio y no permiten derivar las variaciones del módulo elástico en un solo ciclo de vibración. Actualmente, la técnica DAET es la única que permite investigar todo el rango de fenómenos no lineales en el material. Por otra parte, a diferencia de otras técnicas DAET, en este estudio se emplea como contraste una onda continua. El uso de una onda continua permite investigar las variaciones relativas del módulo elástico, para una señal transito
[CAT] L'assaig de determinació de les freqüències de ressonància ha sigut tradicionalment empleat per a determinar la integritat mecànica de testimonis de formigó, en l'avaluació de la conformitat de mescles de formigó en diversos assajos de durabilitat, i en la terminació de propietats constitutives com són el mòdul elàstic i el factor d'amortiment. Esta tècnica no destructiva ha sigut àmpliament apel·lada per a l'avaluació de les propietats mecàniques en tot tipus d'assajos de durabilitat. L'evolució del dany és comunament avaluada a partir de la reducció del mòdul dinàmic, produït com resultat de qualsevol procés de fisuración. No obstant això, el comportament mecànic del formigó és intrínsecament no lineal i presenta histèresi. Com resultat d'un comportament tensió-deformació amb histèresi, el mòdul elàstic depén de la deformació. En assajos dinàmics, la no linealitat del material es manifesta per una disminució de les freqüències de ressonància, la qual és inversament proporcional a l'amplitud d'excitació. Este fenomen és normalment denominat com a dinàmica ràpida. Una vegada l'excitació cessa, el material experimenta un procés de relaxació pel qual, el mòdul elàstic és restaurat a aquell en situació de repòs. Este fenomen és denominat com a dinàmica lenta. Estos fenòmens --dinámicas ràpida i lenta troben el seu origen en la fricció interna del material. Per tant, en materials basats en ciment, la presència de microfissures i les interfícies entre els seus constituents juguen un rol important en la no linealitat mecànica del material. En el context d'avaluació de la durabilitat del formigó, l'evolució del dany està basada en l'increment d'histèresi, com resultat de qualsevol procés de fisuración. En esta tesi s'investiguen tres tècniques diferents les quals utilitzen l'impacte com a mitjà d'excitació de les freqüències de ressonància. La primera tècnica consistix a determinar les freqüències de ressonància a diferents energies d'impacte. La tècnica és denominada en anglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Esta consistix a relacionar el detriment que el material experimenta en les seues freqüències de ressonància, amb l'augment de l'amplitud de l'excitació. La segona tècnica consistix a investigar el comportament no lineal per mitjà de l'anàlisi del senyal corresponent a un sol impacte. Esta consistix a determinar les propietats instantànies de freqüència, atenuació i amplitud. Esta tècnica es denomina, en anglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Es proposen dos tècniques d'extracció del comportament no lineal per mitjà de l'anàlisi de les variacions instantànies de freqüència i atenuació. La primera tècnica consistix en la discretización de la variació de la freqüència amb el temps, per mitjà d'una anàlisi basat en Short-Time Fourier Transform (STFT). La segona tècnica consistix en un ajust per mínims quadrats dels senyals de vibració a un model que considera les variacions de freqüència i atenuació amb el temps. La tercera tècnica empleada en esta tesi pot ser empleada per a l'avaluació d'estructures in situ. La tècnica es tracta d'un assaig acusto-elástico en règim dinàmic. En anglés Dynamic Acousto-Elastic Test (DAET). Les variacions del mòdul elàstic obtingudes per mitjà dels mètodes NIRAS i NSIRAS proporcionen un comportament mitjà i no permeten derivar les variacions del mòdul elàstic en un sol cicle de vibració. Actualment, la tècnica DAET és l'única que permet investigar tot el rang de fenòmens no lineals en el material. D'altra banda, a diferència d'altres tècniques DAET, en este estudi s'empra com contrast una ona contínua. L'ús d'una ona contínua permet investigar les variacions relatives del mòdul elàstic, per a un senyal transitori. A més, permet la inspecció d'elements per mitjà de l'accés per una sola cara.
Eiras Fernández, JN. (2016). Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/71439
TESIS
Premiado
Jin, Meilan. "Signal Structure for a Class of Nonlinear Dynamic Systems". BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6829.
Texto completoLin, Rongming. "Identification of the dynamic characteristics of nonlinear structures". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46888.
Texto completoFerreira, Janito Vaqueiro. "Dynamic response analysis of structures with nonlinear components". Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299871.
Texto completoZolghadrzadehjahromi, Hamed. "Energy consistent nonlinear dynamic contact analysis of structures". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/44339.
Texto completoSaunders, Richard A. "Nonlinear Dynamic Analysis of Structures with Hyperelastic Devices". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/42691.
Texto completoMaster of Science
Nieto, ferro Alex. "Nonlinear Dynamic Soil-Structure Interaction in Earthquake Engineering". Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2013. http://www.theses.fr/2013ECAP0006/document.
Texto completoThe present work addresses a computational methodology to solve dynamic problems coupling time and Laplace domain discretizations within a domain decomposition approach. In particular, the proposed methodology aims at meeting the industrial need of performing more accurate seismic risk assessments by accounting for three-dimensional dynamic soil-structure interaction (DSSI) in nonlinear analysis. Two subdomains are considered in this problem. On the one hand, the linear and unbounded domain of soil which is modelled by an impedance operator computed in the Laplace domain using a Boundary Element (BE) method; and, on the other hand, the superstructure which refers not only to the structure and its foundations but also to a region of soil that possibly exhibits nonlinear behaviour. The latter subdomain is formulated in the time domain and discretized using a Finite Element (FE) method. In this framework, the DSSI forces are expressed as a time convolution integral whose kernel is the inverse Laplace transform of the soil impedance matrix. In order to evaluate this convolution in the time domain by means of the soil impedance matrix (available in the Laplace domain), a Convolution Quadrature-based approach called the Hybrid Laplace-Time domain Approach (HLTA), is thus introduced. Its numerical stability when coupled to Newmark time integration schemes is subsequently investigated through several numerical examples of DSSI applications in linear and nonlinear analyses. The HLTA is finally tested on a more complex numerical model, closer to that of an industrial seismic application, and good results are obtained when compared to the reference solutions
Nieto, Ferro Alex. "Nonlinear Dynamic Soil-Structure Interaction in Earthquake Engineering". Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00944139.
Texto completoBowden, Mary L. "Dynamics of space structures with nonlinear joints". Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14575.
Texto completoLiu, Shaobin. "Continuum Sensitivity Method for Nonlinear Dynamic Aeroelasticity". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23282.
Texto completoaerodynamic loads. The continuum sensitivity equations (CSE) are a set of linear partial
differential equations (PDEs) obtained by differentiating the original governing equations of
the physical system. The linear CSEs may be solved by using the same numerical method
used for the original analysis problem. The material (total) derivative, the local (partial)
derivative, and their relationship is introduced for shape sensitivity analysis. The CSEs are
often posed in terms of local derivatives (local form) for fluid applications and in terms of total
derivatives (total form) for structural applications. The local form CSE avoids computing
mesh sensitivity throughout the domain, as required by discrete analytic sensitivity methods.
The application of local form CSEs to built-up structures is investigated. The difficulty
of implementing local form CSEs for built-up structures due to the discontinuity of local
sensitivity variables is pointed out and a special treatment is introduced. The application
of the local form and the total form CSE methods to aeroelastic problems are compared.
Their advantages and disadvantages are discussed, based on their derivations, efficiency,
and accuracy. Under certain conditions, the total form continuum method is shown to be
equivalent to the analytic discrete method, after discretization, for systems governed by a
general second-order PDE. The advantage of the continuum sensitivity method is that less
information of the source code of the analysis solver is required. Verification examples are
solved for shape sensitivity of elastic, fluid and aeroelastic problems.
Ph. D.