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1
Xia, Kaiwen Rosakis Ares J. "Laboratory investigations of earthquake dynamics /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-02262005-161824.
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Grzemba, Birthe [Verfasser]. "Predictability of Elementary Models for Earthquake Dynamics / Birthe Grzemba." Berlin : epubli GmbH, 2014. http://d-nb.info/1063227674/34.
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Abercrombie, Rachel E. "Earthquake rupture dynamics and neotectonics in the Aegean region." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290297.
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Bruun, Karianne. "Structural Dynamics of Subsea Structures in Earthquake Prone Regions." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24328.
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Med utviklingen som har funnet sted innenfor den norske oljebransjen de siste årene har både teknologien og utfordringene blitt mer komplekse. Subsea-operasjoner har blitt mer vanlig og gir utslag i at det på havbunnen i mange felt er sammenkoblede systemer av konstruksjoner. I relasjon til seismisk aktivitet reises da spørsmålet om disse systemene med brønner, rør og andre konstruksjoner kan tåle å bli utsatt for et jordskjelv av en viss størrelse. For å ta et steg i retningen av å besvare dette spørsmålet, dreier denne hovedoppgaven seg om studien av en beskyttelseskonstruksjon som utsettes for grunnakselerasjoner funnet ved probabilistisk evaluering av valgte jordskjelvdata tilgjengelig for den norske kontinentalsokkelen.Den valgte konstruksjonen er lokalisert i Åsgårdfeltet på Haltenbanken vest for midt-Norge. Det er en ganske liten og slank konstruksjon hvis funksjon er å beskytte oljeinstallasjoner fra eventuelle skader forårsaket fra trål og fallende objekter i forbindelse med fiskeriindustrien. I modelleringen av konstruksjonen vurderes den som et produkt av tre forskjellige systemer. Det første systemet er konstruksjonen alene, det andre systemet er jordsystemet og det tredje er fluidsystemet. Dermed ble tre modeller laget der de forskjellige systemegenskapene (fjærer/dempere, hydrodynamiske krefter) ble introdusert stegvis.For å undersøke konstruksjonens respons i forhold til påsatte grunnakselerasjoner, måtte representative tidsrekker for jordskjelv brukes. Disse tidsrekkene ble funnet ved hjelp av probabilistisk vurdering av en syntetisk jorskjelvkatalog. Denne jordskjelvkatalogen ble generert ved å bruke Gutenberg-Richter relasjonen, og de tilhørende parametrene og områdene de gjelder for ble funnet i en rapport angående seismisk inndeling av Norge \cite{zonation}. Jordskjelvparameteren som ble valgt var maksimum grunnakselerasjon (PGA) i både horisontal og vertikal retning estimert ved en relasjon funnet av Ambraseys, med flere \cite{ambhor}\cite{ambver}. Videre ble ordningsstatistikk brukt på de genererte PGA-verdiene ved å bruke Gumbels fordeling for maksima. De resulterende PGA-verdiene i horisontal og vertikal retning ble så brukt for å finne en passende tidsrekke for akselerasjon i en database over jordskjelv for Europa og Midtøsten \cite{esmd}. Deretter ble disse akselerasjonene påsatt de tre modellene og responsen ble evaluert ved ikkelineær direkte implisitt integrasjon. Videre ble en modal analysis av responene utført på den fullt neddykkede modellen for sammenlikningens skyld. Enda en tidsserie ble også påsatt den fullt neddykkede modellen som ble generert basert på det området med høyest seismisk aktivitet, funnet i rapporten nevnt ovenfor for å vurdere det verst tenkelige tilfellet.Resultatene av disse analysene viste at med introduksjon av jord-konstruksjon-interaksjon modellert ved fjærer og dempere, så økte forskyvningene sammenliknet med den fast innspente modellen (konstruksjonen alene). Videre så økte forskyvningene ytterligere ved å introdusere hydrodynamiske krefter. På grunn av små forskyvninger dominerte treghetskreftene responsen for den neddykkede modellen. Med tanke på konstruksjonens oppførsel så ble konstruksjonen nesten ikke affisert av de påsatte grunnakselerasjonene - som er et godt tegn. Imidlertid er det vanskelig å konkludere hvordan andre typer konstruksjoner som rør og platformer ville ha respondert hvis de ble utsatt for de samme grunnakselerasjonene ettersom disse har mye større dimensjoner og annerledes geometri.
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Stojanova, Menka. "Non-trivial aftershock properties in subcritical fracture and in earthquake dynamics." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10201.
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Pas de résuméThis thesis consists in two separate parts: one on subcritical fracture experiments, and another one on earthquake statistics. The dynamics of these processes was mainly studied through their scale invariant dynamics, reflected in power law distri- butions of event sizes and times between events. The analyses focuses particularly on the variation of their exponent values and the origins of these variations. Subcritical fracture was studied by two experimental set-ups: creep experiments on paper, and constant-strain fracture of fibre bundles. Paper fracture has been studied in our group for more than 10 years now by visually observing the propaga- tion of the crack. We added acoustic emission monitoring to the experimental set-up in order to compare it to visualisation. The comparison between low frequency image analysis and the high frequency acoustic monitoring allowed to identify the impor- tance of the frequency of analysis for temporally correlated systems, and acoustic emission monitoring revealed the existence of aftershocks in the dynamics of paper fracture. The fibre bundle experiments concentrate on the temporal distribution of the frac- ture events, which follows an Omori law. We studied the influence of the temperature and stress on its exponent, and compared it with results from fibre bundle model analytical predictions and simulations. Our work on earthquakes was initially motivated by the results obtained on pa- per fracture experiments. Hence it starts by a study of aftershock sequences, their Gutenberg-Richter exponent, and the influence of the frequency of analysis on this exponent. By lowering the frequency of the time-magnitude signal we showed that at low frequencies the exponent of the Gutenberg-Richter law depends on the expo- nent of the Omori law. The last chapter of this thesis is concentrated on the early aftershocks. We in- spected the evolution of the properties of an aftershock sequence with time, and observed differences between aftershock occurring shortly after a mainshock, and late aftershocks. These results can be related to the recent proposition of existence of magnitude correlations in earthquakes
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Castle, John C. "Imaging mid-mantle discontinuities : implications for mantle chemistry, dynamics, rheology, and deep earthquakes /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6809.
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Doherty, Kevin Thomas. "An investigation of the weak links in the seismic load path of unreinforced masonary buildings /." Title page, table of contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phd655.pdf.
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Nieto, Ferro Alex. "Nonlinear Dynamic Soil-Structure Interaction in Earthquake Engineering." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00944139.
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The 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.
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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.
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Ce travail détaille une approche de calcul pour la résolution de problèmes dynamiques qui combinent des discrétisations en temps et dans le domaine de Laplace reposant sur une technique de sous-structuration. En particulier, la méthode développée cherche à remplir le besoin industriel de réaliser des calculs dynamiques tridimensionnels pour le risque sismique en prenant en compte des effets non-linéaires d'interaction sol-structure (ISS). Deux sous-domaines sont considérés dans ce problème. D'une part, le domaine de sol linéaire et non-borné qui est modélisé par une impédance de bord discrétisée dans le domaine de Laplace au moyen d'une méthode d'éléments de frontière ; et, de l'autre part, la superstructure qui fait référence pas seulement à la structure et sa fondation mais aussi, éventuellement, à une partie du sol présentant un comportement non-linéaire. Ce dernier sous-domaine est formulé dans le domaine temporel et discrétisé avec la méthode des éléments finis (FE). Dans ce cadre, les forces liées à l'ISS s'écrivent sous la forme d'une intégrale de convolution en temps dont le noyau est la transformée de Laplace inverse de la matrice d'impédance de sol. Pour pouvoir évaluer cette convolution dans le domaine temporel à partir d'une impédance de sol définie dans le domaine de Laplace, une approche basée sur des Quadratures de Convolution (QC) est présentée : la méthode hybride Laplace-Temps (L-T). La stabilité numérique de son couplage avec un schéma d'intégration de type Newmark est ensuite étudiée sur plusieurs modèles d'ISS en dynamique linéaire et non-linéaire. Finalement, la méthode L-T est testée sur un modèle numérique plus complexe, proche d'une application sismique de caractère industriel, et des résultats satisfaisants sont obtenus par rapport aux solutions de référenceThe 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
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Purssell, Tanis Jane. "Modulus reduction dynamic analysis." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25136.
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A semi-analytical method of dynamic analysis, capable of predicting both the magnitude and pattern of earthquake induced deformations, is presented. The analysis is based on a modulus reduction approach which uses a reduced modulus to simulate the softening induced in soils during cyclic loading. The effects of the inertia forces developed during dynamic loading on the induced deformations are also included through an appropriate selection of the reduced modulus.
The reduced modulus is utilized in a static stress-strain analysis to predict the magnitude and pattern of the deformations induced during earthquake loading. The appropriate modulus reduction is determined from laboratory tests on undisturbed soil samples. Three methods of computing a suitable post-cyclic modulus were investigated but only the cyclic strain approach, in which the modulus is determined from cyclic loading tests that duplicate the field stress conditions, yields reductions of sufficient magnitude to provide realistic estimates of earthquake induced deformations.
The modulus reduction analysis was used to predict the deformations occurring during dynamic loading of a model tailings slope in a laboratory shaking table test and of the Upper San Fernando Dam during the earthquake of February, 1971. These studies showed that the modulus reduction analysis is capable of reproducing the dynamically induced deformations and that reductions in the modulus of up to 1000 times may be required. Unfortunately, limitations of the testing equipment and inadequacies in the available data required that the appropriate modulus reductions could not be determined entirely through laboratory and field investigations. Some assumptions were necessary in selecting the reduced modulus values used in the analyses. Although these case studies were, hence, unable to provide full verification of the proposed method, they do demonstrate the reliability and simplicity of the analysis as a method of assessing the performance of soil structures during earthquake loading.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
11
Weston, Neil R. "Development of energy dissipating ductile cladding for passive control of building seismic response." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/13052.
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Hsu, Cheng-Chieh. "Control of seismic response of building structures using passive cladding and active tendon systems." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/20747.
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Jeong, Seokho. "Topographic amplification of seismic motion including nonlinear response." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50325.
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Topography effects, the modification of seismic motion by topographic features, have been long recognized to play a key role in elevating seismic risk. Site response, the modification of ground motion by near surface soft soils, has been also shown to strongly affect the amplitude, frequency and duration of seismic motion. Both topography effects and 1-D site response have been extensively studied through field observations, small-scale and field experiments, analytical models and numerical simulations, but each one has been studied independently of the other: studies on topography effects are based on the assumption of a homogeneous elastic halfspace, while 1-D site response studies are almost exclusively formulated for flat earth surface conditions.
This thesis investigates the interaction between topographic and soil amplification, focusing on strong ground motions that frequently trigger nonlinear soil response. Recently, a series of centrifuge experiments tested the seismic response of single slopes of various inclination angles at the NEES@UCDavis facility, to investigate the effects of nonlinear soil response on topographic amplification. As part of this collaborative effort, we extended the search space of these experiments using finite element simulations. We first used simulations to determine whether the centrifuge experimental results were representative of free-field conditions. We specifically investigated whether wave reflections caused by the laminar box interfered with mode conversion and wave scattering that govern topographic amplification; and whether this interference was significant enough to qualitatively alter the observed amplification compared to free-field conditions. We found that the laminar box boundaries caused spurious reflections that affected the response near the boundaries; however its effect to the crest-to-free field spectral ratio was found to be insignificant. Most importantly though, we found that the baseplate was instrumental in trapping and amplifying waves scattered and diffracted by the slope, and that in absence of those reflections, topographic amplification would have been negligible. We then used box- and baseplate-free numerical models to study the coupling between topography effects and soil amplification in free-field conditions.
Our results showed that the complex wavefield that characterizes the response of topographic features with non-homogeneous soil cannot be predicted by the superposition of topography effects and site response, as is the widespread assumption of engineering and seismological models. We also found that the coupling of soil and topographic amplification occurs both for weak and strong motions, and for pressure-dependent media (Nevada sand), nonlinear soil response further aggravates topographic amplification; we attributed this phenomenon to the reduction of apparent velocity that the low velocity layers suffer during strong ground motion, which intensifies the impedance contrast and accentuates the energy trapping and reverberations in the low strength surficial layers. We finally highlighted the catalytic effects that soil stratigraphy can have in topographic amplification through a case study from the 2010 Haiti Earthquake. Results presented in this thesis imply that topography effects vary significantly with soil stratigraphy, and the two phenomena should be accounted for as a coupled process in seismic code provisions and seismological ground motion predictive models.
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Goetz, Ryan P. Rosenblad Brent L. "Study of the horizontal-to-vertical spectral ratio (HVSR) method for characterization of deep soils in the Mississippi Embayment." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/5334.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on December 22, 2009). Thesis advisor: Dr. Brent L. Rosenblad. Includes bibliographical references.
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Heider, Yousef [Verfasser], and Wolfgang [Akademischer Betreuer] Ehlers. "Saturated porous media dynamics with application to earthquake engineering / Yousef Heider. Betreuer: Wolfgang Ehlers." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2012. http://d-nb.info/1028801181/34.
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Uliana, David A. "The effects of earthquake excitations on reticulated domes." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45667.
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Comparisons were made on the behavior of two full-sized reticulated domes subjected to uniform static loads only and uniform static loads with earthquake excitations. Space truss elements were used in the dome models. The stiffness matrix of the space truss element allows for the nonlinear strain-displacement behavior and the stress-strain behavior of the material is modeled with a bilinear approximation. The nonlinear solution technique is the Newton-Raphson method while the direct integration technique is the Newmark- Beta method.
The joint displacements for the static and the dynamic analyses were compared for both domes along with the axial stresses in all members. The percentage increases in the axial stresses of the dynamic analyses as compared to those of the static analyses were determined.
The reticulated domes used in the study were found to bet capable of withstanding the earthquake excitations when subjected to various uniform loads without failure.
Master of Science
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Clément, Denis Emile. "Seismic analysis of knee elements for steel frames." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:c69aee93-4489-486c-a5fe-11685728e903.
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The 1994 Northridge and 1995 Kobe earthquakes, which were moderate in seismological terms, showed that many buildings were subjected to demolition or very expensive repairs because of severe damage in principle members, mainly in the column-beam connections. As a result, the development of dissipative systems was encouraged, which limit the damage parts to easily replaceable elements, in case of moderate earthquakes. One such system is the knee braced frame. Knee braced frames are a modified form of cross bracing in which the brace is cut short and connected to the mid point of a knee element spanning between the adjacent beam and column. The key component is the knee element, which controls both the initial elastic stiffness of the frame, and the onset of yield and subsequent energy dissipation. The knee elements are required to ensure energy absorption through repeated large deformations without suffering collapse or instability. This thesis describes the development of different knee element designs and their performance assessments. It is shown that the dissipative mechanism of the web yielding in shear is advantageous because it is independent of the moment distribution and it does not affect the connections and extends the dissipative zones to all its lengths. Extensive finite element modelling and experimental testing have been undertaken. In the shear yielding mode excellent performance was achieved using standard hot rolled sections, modified by the addition of web stiffeners to prevent localised buckling failure. Weakening of the knee element's webs so that it yields very early in an earthquake has potential benefit, but is shown to be unsafe as it promotes premature failure of the element. A knee element model for non-linear dynamic analysis of an entire building has been developed. Time history analyses showed that knee braced frames with the developed knee element have a large global ductility and an outstanding performance. Results obtained with different pushover analysis methods (Eurocode 8, FEMA-356 and ATC-40) have been compared to those obtained wit the time history analyses. Moreover FEMA-356 method, which includes a more accurate representation of the structure's significant post-yield stiffness, gave the closest agreement with the time history analyses and is recommended for the design of knee braced frames.
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Freed, Andrew Mark. "Viscoelastic solutions to tectonic problems of extinct spreading centers, earthquake triggering, and subduction zone dynamics." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282600.
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This dissertation uses a finite element technique to explore the role of viscoelastic behavior in a wide range of plate tectonic processes. We consider problems associated with spreading centers, earthquake triggering, and subduction zone dynamics. We simulated the evolution of a slow-spreading center upon cessation of active spreading in order to predict long-term changes in the axial valley morphology. Results suggest that the axial valley created at a slow-spreading center persists because the crust is too strong to deform ductily and because no effective mechanism exists to reverse the topography created by rift-bounding normal faults. These results suggest that the persistence of axial valleys at extinct spreading centers is consistent with a lithospheric stretching model based on dynamic forces for active slow-spreading ridges. In our study of earthquake triggering, results suggest that if a ductile lower crust or upper mantle flows viscously following a thrust event, relaxation may cause a transfer of stress to the upper crust. Under certain conditions this may lead to further increases and a lateral expansion of high Coulomb stresses along the base of the upper crust. Analysis of experimentally determined non-Newtonian flow laws suggests that wet granitic, quartz, and feldspar aggregates may yield a viscosity on the order of 1019 Pa-s. The calculated rate of stress transfer from a viscous lower crust or upper mantle to the upper crust becomes faster with increasing values of the power law exponent and the presence of a regional compressive strain rate. In our study of subduction zone dynamics, we model the density and strength structures that drive the Nazca and South American plates. Results suggest that chemical buoyancy and phase changes associated with a cool subducting slab strongly influence the magnitude of driving forces, and the downgoing slab behaves weaker than the strength that would be expected based solely on temperature. Additionally, results suggest that large stresses are produced on the western margin of South American due to forces associated with asthenospheric cornerflow. These forces may be responsible for the high topography of the South American Cordilleran.
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Michel, Sylvain. "From fault dynamics to seismic hazard assessment." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/284397.
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My work focused on the development of improved methodologies for the evaluation of seismic hazard and its related uncertainties, based on the study of active faults systems and dynamic modelling of the seismic cycle. I worked in particular on the probabilistic estimate of a fault's maximum magnitude earthquake and of its return period. Those parameters are indeed crucial to estimate seismic hazard. Seismicity can be viewed as a stochastic process which is constrained by the principle of moment conservation: seismic ruptures must in principle rupture fault portions which had accumulated a deficit of slip, in view of their long term slip rate, during the interseismic period. In Chapter 1, I explain how we implemented those constraints in the evaluation of the probability distribution describing the magnitude and return period of the largest earthquake, propagating the geodetic uncertainties up to the hazard calculation. We applied this methodology to the Parkfield Segment of the San Andreas Fault, where the seismic cycle is particularly well documented. Our study implies potential maximum magnitude between 6.5 and 7.5, with a return period of 140 to 300 years. In Chapter 2, we applied the same methodology to the Cascadia subduction zone, known to have produced a M~9 earthquake in 1700 but where the seismic hazard remains poorly constrained. As part of this study we determined a model of interseismic coupling and of fault slip due to Slow Slip Events using an Independent Component Analysis-based inversion method. Finally, in Chapter 3, I use dynamic modelling to tackle the problem of partial ruptures. Large earthquakes tend to be confined to fault areas locked in the interseismic period but they often rupture them only partially. For example, during the 2015 M7.8 Gorkha earthquake, Nepal, a slip pulse propagating along-strike unzipped the bottom edge of the locked portion of the Main Himalayan Thrust. The lower edge of the rupture produced dominant high-frequency (>1 Hz) radiation of seismic waves. We showed that similar partial ruptures occur spontaneously in a simple dynamic model of earthquake sequences on a planar fault without mechanical, frictional and geometrical heterogeneities.
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Sarvghad-Moghadam, Abdoreza. "Seismic torsional response of asymmetrical multi-storey frame buildings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42874.pdf.
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Mathur, Ravindra Prasad. "A new hybrid method for three-dimensional dynamic soil-structure interaction." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184665.
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A hybrid method based on three-dimensional finite element idealization in the near field and a semi-analytic scheme using the principles of wave propagation in multilayered half space in the far field is proposed for dynamic soil-structure interaction analysis. It combines the advantages of both the numerical and analytical techniques. A structure resting on the surface or embedded in a multilayered soil-medium and subjected to vertically propagating plane waves is analyzed by using the method. An important aspect of the soil-structure interaction problem considered is the presence of waves scattered from the soil-structure interface and geometrical irregularities in the soil. The dynamic response of an embedded structure of rectangular cross section to a vertically propagating compressional pulse is solved as an example problem. The proposed method is verified by comparison of its predictions with those from a finite element procedure with absorbing boundaries, and from an analytical solution. The results from the hybrid method compare well with those from the other two, with closer correlation between the hybrid and analytical methods.
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Scala, Antonio <1985>. "Rupture Dynamics Along Subduction Zones: Structural and Geometrical Complexities and the Case of Tohoku-Oki Earthquake." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7489/1/Thesis_Antonio_Scala.pdf.
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We aim to characterize the rupture dynamics along the subduction zones. We investigated the shear/normal stress coupling when geometrical discontinuities and/or realistic velocity fields induce normal traction perturbations.
The Spectral Element Method (SEM) is shown to be a powerful numerical tool to perform dynamic simulations for subduction earthquakes due to its geometrical flexibility and to the easy implementation of classical seismological boundary conditions.
Sharp variations of normal stress are induced when a rupture propagates between dissimilar materials. Performing dynamic simulations along bimaterial interfaces, we show how the Coulomb friction law leads to unstable solutions due to the missing time/length scale of shear/normal coupling. We also show how the shear stress response has to be properly delayed to provide stable physical reliable solutions and how this delay can allow to define a length, comparable with the dissipation zone, which can be interpreted as the length of coupling.
Free surface interaction is shown to generate a break of symmetry in the shallow part of dipping faults. In particular larger ground motion on the hanging wall and thus larger coseismic slip is evidenced. Due to the fault/free surface interaction this slip is shown to be generally associated with low-frequency radiation.
Finally, exploiting these results some dynamic models of Tohoku earthquake are presented. The main source features of that event can be addressed in terms of influence of geometry and structure and thus of shear/normal coupling. Along dip we find a bilateral rupture faster trenchward where the largest coseismic slip is measured. Strong rupture accelerations due to geometrical and velocity discontinuities imply high-frequency sub-sources in the deep part of the subduction.
We finally show how taking into account these dynamic features the tsunami scenarios for the Tohoku earthquake lead to higher estimates for tsunami hazard.
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Scala, Antonio <1985>. "Rupture Dynamics Along Subduction Zones: Structural and Geometrical Complexities and the Case of Tohoku-Oki Earthquake." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7489/.
Full textAbstract:
We aim to characterize the rupture dynamics along the subduction zones. We investigated the shear/normal stress coupling when geometrical discontinuities and/or realistic velocity fields induce normal traction perturbations.
The Spectral Element Method (SEM) is shown to be a powerful numerical tool to perform dynamic simulations for subduction earthquakes due to its geometrical flexibility and to the easy implementation of classical seismological boundary conditions.
Sharp variations of normal stress are induced when a rupture propagates between dissimilar materials. Performing dynamic simulations along bimaterial interfaces, we show how the Coulomb friction law leads to unstable solutions due to the missing time/length scale of shear/normal coupling. We also show how the shear stress response has to be properly delayed to provide stable physical reliable solutions and how this delay can allow to define a length, comparable with the dissipation zone, which can be interpreted as the length of coupling.
Free surface interaction is shown to generate a break of symmetry in the shallow part of dipping faults. In particular larger ground motion on the hanging wall and thus larger coseismic slip is evidenced. Due to the fault/free surface interaction this slip is shown to be generally associated with low-frequency radiation.
Finally, exploiting these results some dynamic models of Tohoku earthquake are presented. The main source features of that event can be addressed in terms of influence of geometry and structure and thus of shear/normal coupling. Along dip we find a bilateral rupture faster trenchward where the largest coseismic slip is measured. Strong rupture accelerations due to geometrical and velocity discontinuities imply high-frequency sub-sources in the deep part of the subduction.
We finally show how taking into account these dynamic features the tsunami scenarios for the Tohoku earthquake lead to higher estimates for tsunami hazard.
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O'Reilly, Ossian. "Coupled High-Order Finite Difference and Unstructured Finite Volume Methods for Earthquake Rupture Dynamics in Complex Geometries." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-155471.
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The linear elastodynamic two-dimensional anti-plane stress problem, where deformations occur in only one direction is considered for one sided non-planar faults. Fault dynamics are modeled using purely velocity dependent friction laws, and applied on boundaries with complex geometry. Summation-by-parts operators and energy estimates are used to couple a high-order finite difference method with an unstructured finite volume method. The unstructured finite volume method is used near the fault and the high-order finite difference method further away from the fault where no complex geometry is present. Boundary conditions are imposed weakly on characteristic form using the simultaneous approximation term technique, allowing explicit time integration to be used. Numerical computations are performed to verify the accuracy and time stability, of the method.
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Kosbab, Benjamin David. "Seismic performance evaluation of port container cranes allowed to uplift." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33921.
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The seismic behavior of port container cranes has been largely ignored-by owners, operators, engineers, and code officials alike. This is despite their importance to daily port operations, where historical evidence suggests that port operational downtime following a seismic event can have a crippling effect on the affected local, regional, and national economies. Because the replacement time in the event of crane collapse can be a year or more, crane collapse has the potential to be the "critical path" for post-disaster port recovery. Since the 1960's, crane designers allowed and encouraged an uplift response from container cranes, assuming that this uplift would provide a "safety valve" for seismic loading; i.e. the structural response at the onset of uplift was assumed to be the maximum structural response. However, cranes have grown much larger and more stable such that the port industry is now beginning to question the seismic performance of their modern jumbo container cranes.
This research takes a step back, and reconsiders the effect that uplift response has on the seismic demand of portal-frame structures such as container cranes. A theoretical estimation is derived which accounts for the uplift behavior, and finds that the "safety valve" design assumption can be unconservative. The resulting portal uplift theory is verified with complex finite element models and experimental shake-table testing of a scaled example container crane. Using the verified models, fragility curves and downtime estimates are developed which characterize the risk of crane damage and operational downtime for three representative container cranes subjected to a range of earthquakes. This research demonstrates that container cranes designed using previous and current standards can significantly contribute to port seismic vulnerability. Lastly, performance-based design recommendations are provided which encourage the comparison of demand and capacity in terms of the critical portal deformation, using the derived portal uplift theory to estimate seismic deformation demand.
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Quintana-Gallo, Patricio Ignacio. "The Nonlinear Dynamics Involved in the Seismic Assessment and Retrofit of Reinforced Concrete Buildings." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2014. http://hdl.handle.net/10092/9999.
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Seismically vulnerable buildings constitute a major problem for the safety of human beings. In many parts of the world, reinforced concrete (RC) frame buildings designed and constructed with substandard detailing, no consideration of capacity design principles, and improper or no inclusion of the seismic actions, have been identified. Amongst those vulnerable building, one particular typology representative of the construction practice of the years previous to the 1970’s, that most likely represents the worst case scenario, has been widely investigated in the past. The deficiencies of that building typology are related to non-ductile detailing in beam column joints such as the use of plain round bars, the lack of stirrups inside the joint around the longitudinal reinforcement of the column, the use of 180° end hooks in the beams, the use of lap splices in potential ‘plastic hinge’ regions, and substandard quality of the materials. That type of detailing and the lack of a capacity design philosophy create a very fragile fuse in the structure where brittle inelastic behaviour is expected to occur, which is the panel zone region of exterior beam column joints.
The non-ductile typology described above was extensively investigated at the University of Canterbury in the context of the project ‘Retrofit Solutions for New Zealand Multi-Storey Buildings’ (2004-2011), founded by the ‘Foundation for Research, Science and Technology’ Tūāpapa Rangahau Pūtaiao. The experimental campaign prior to the research carried out by the author consisted of quasi-static tests of beam column joint subassemblies subjected to lateral loading regime, with constant and varying axial load in the column. Most of those specimens were representative of a plane 2D frame (knee joint), while others represented a portion of a space 3D frame (corner joints), and only few of them had a floor slab, transverse beams, and lap splices. Using those experiments, several feasible, cost-effective, and non-invasive retrofit techniques were developed, improved, and refined. Nevertheless, the slow motion nature of those experiments did not take into account the dynamical component inherent to earthquake related problems. Amongst the set of techniques investigated, the use of FRP layers for strengthening beam column joints is of particular interest due to its versatility and the momentum that its use has gained in the current state of the practice. That particular retrofit technique was previously used to develop a strengthening scheme suitable for plane 2D and space 3D corner beam column joints, but lacking of floor slabs. In addition, a similar scheme was not developed for exterior joints of internal frames, referred here as ‘cruciform’.
In this research a 2/5 scale RC frame model building comprising of two frames in parallel (external and internal) joined together by means of floor slabs and transverse beams, with non-ductile characteristics identical to those of the specimens investigated previously by others, and also including lap splices, was developed. In order to investigate the dynamic response of that building, a series of shake table tests with different ground motions were performed. After the first series of tests, the specimen was modified by connecting the spliced reinforcement in the columns in order to capture a different failure mode. Ground motions recorded during seismic events that occurred during the initial period of the experimental campaign (2010) were used in the subsequent experiments. The hierarchy of strengths and sequence of events in the panel zone region were evaluated in an extended version of the bending moment-axial load (M-N) performance domain developed by others. That extension was required due to the asymmetry in the beam cross section introduced by the floor slab. In addition, the effect of the torsion resistance provided by the spandrel (transverse beam) was included.
In order to upgrade the brittle and unstable performance of the as-built/repaired specimen, a practical and suitable ad-hoc FRP retrofit intervention was developed, following a partial retrofit strategy that aimed to strengthen exterior beam column joints only (corner and cruciform). The ability of the new FRP scheme to revert the sequence of events in the panel zone region was evaluated using the extended version of the M-N performance domain as well as the guidelines for strengthening plane joints developed by others. Weakening of the floor slab in a novel configuration was also incorporated with the purpose of reducing the flexural capacity of the beam under negative bending moment (slab in tension), enabling the damage relocation from the joint into the beam. The efficacy of the developed retrofit intervention in upgrading the seismic performance of the as-built specimen was investigated using shake table tests with the input motions used in the experiments of the as-built/repaired specimen.
Numerical work aimed to predict the response of the model building during the most relevant shake table tests was carried out. By using a simple numerical model with concentrated plasticity elements constructed in Ruaumoko2D, the results of blind and post-experimental predictions of the response of the specimen were addressed. Differences in the predicted response of the building using the nominal and the actual recorded motions of the shake table were investigated. The dependence of the accuracy of the numerical predictions on the assumed values of the parameters that control the hysteresis rules of key structural members was reviewed.
During the execution of the experimental campaign part of this thesis, two major earthquakes affected the central part of Chile (27 of February 2010 Maule earthquake) and the Canterbury region in New Zealand (22 February 2011 Canterbury earthquake), respectively. As the author had the opportunity to experience those events and investigate their consequences in structures, the observations related to non-ductile detailing and drawbacks in the state of the practice related to reinforced concrete walls was also addressed in this research, resulting in preliminary recommendations for the refinement of current seismic code provisions and assessment guidelines. The investigations of the ground motions recorded during those and other earthquakes were used to review the procedures related to the input motions used for nonlinear dynamic analysis of buildings as required by most of the current code provisions. Inelastic displacement spectra were constructed using ground motions recorded during the earthquakes mentioned above, in order to investigate the adequacy of modification factors used to obtain reduced design spectra from elastic counterparts. Finally a simplified assessment procedure for RC walls that incorporates capacity compatible spectral demands is proposed.
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Flores, Cuba Joseph M. "Earthquake rupture around stepovers in a brittle damage medium." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS301.pdf.
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Les systèmes de failles décrochantes sont constitués d’une variété de complexités géométriques telles que des branchements de failles, des plis et des zones de relais. En particulier, la présence d’une structure de relais peut fortement déterminer la taille finale de la rupture sismique. Ainsi, comprendre la dynamique d’une rupture à travers une telle complexité est crucial pour l’évaluation des risques sismiques. Quelques études ont examiné cette question dans le contexte d’un milieu élastique linéaire. Cependant, lors d’un séisme, des zones d’endommagement sont générées, notamment aux extrémités d’une faille, ce qui modifie considérablement la dynamique globale d’une rupture. En utilisant un modèle micromécanique prenant en compte la croissance et l’ouverture de fissures et leur impact sur l’évolution dynamique des modules élastiques, nous évaluons comment l’endommagement dynamique peut affecter la capacité d’une rupture à se propager au travers des structures de relais. Nous montrons que, parfois, en tenant compte de cette dispersion de l’énergie sur les microstructures formées, les zones endommagées suppriment la capacité de la rupture à passer d’une faille à une autre. Mais, dans certains cas spécifiques, la zone de faible vitesse créée dynamiquement peut au contraire aider la rupture à sauter sur la deuxième faille. En combinant cette étude numérique avec une approche analytique, nous établissons les contours d’une approche systématique utile pour l’évaluation des risques sismiquesStrike-slip fault systems consist of a variety of geometrical complexities like branches, kinks and step-overs. Especially, the presence of a step-over structure can strongly determine the final size of the earthquake rupture. Thus understanding the dynamics of a rupture through such a complexity is crucial for seismic hazard assessment. A few studies have looked at this question within the context of a linear elastic medium. However, during an earthquake off-fault damage is generated, especially at the ends of a fault, which significantly changes the overall dynamics of a rupture. Using a micromechanical model, that accounts for crack growth and opening and its impact on the dynamic evolution of elastic moduli, we evaluate how dynamic off-fault damage can affect the capability of a rupture to navigate through step-over fault structures. We show that, sometimes, accounting for this energy sink, off-damage suppresses the ability of the rupture to jump from one fault to another. Whereas, in some specific cases, the dynamically created low-velocity zone may aid the rupture to jump on the secondary fault. Combing this numerical study with an analytical analysis we set the contours for a systematic approach useful for earthquake hazard assessments
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Hutton, Nicole Suzanne. "Population Dynamics and Vulnerability Reduction: The Role of Non-Profit Organizations Following the 2011 Earthquake in Christchurch, New Zealand." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/5964.
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With the adoption of neo-liberal policies and the decline in social welfare, non-profit organizations have been increasingly integrated into public service provision. Such changes raise questions regarding formal policies and access for marginalized populations, no more so than in disaster settings as formal disaster management of sexual health services are still vague. This study identifies the role of non-profit organizations in providing public health and social services through the lens of sexual health commitments following the September 2010 Darfield Earthquake and subsequent major aftershock during February 2011 in Christchurch, New Zealand. The primary goals of this study were three fold, to delineate i) aspects of non-profit organizational culture and agency connections that contributed to the resilience of non-profit organizations by maintaining and adapting access to sexual health and associated wellbeing services over the transition from response to recovery ii) integration pathways of non-profit organizations into disaster risk reduction and iii) appropriate geographic representations of temporal vulnerability change impacting the commitments of non-profit organizations.
Mixed methods were used for this study. Data were collected over a two-year period between 2013 and 2015. Data collection techniques included: i) archival research ii) surveys iii) focus groups and iv) semi-structured interviews. Quantitative data were derived from census records and qualitative data from surveys, focus groups, and interviews with non-profit and civil society practitioners. A total of thirty-six non-profit organizations, civil society partners, and agency connections participated.
Results show that sexual health needs of youth, families, and migrants arriving for the rebuild, fluctuated following the earthquakes. Sexual health non-profits absorbed the shifting demands for services and supplies by leveraging government partnerships and non-profit agency connections to account for fluctuations in presenting populations, adjust service delivery methods and continue advocacy campaigns. Also, as a result of functional redundancy amongst migrant support groups and their respective agency connections, strategies of long-term advocacy commitment, co-location, and relationship building with diverse ethnic groups benefitted migrants and refugees in maintaining or accessing adequate health and wellbeing support into the recovery phase. By developing programs to increase public awareness of resources, creating engagement opportunities in vacant spaces, and bringing a united voice to authorities, non-profits captured increased social cohesion to address emergent and compounded vulnerabilities of marginalized populations. However, as the recovery progressed, some collective energy was lost.
Findings indicate that non-profits operating in Christchurch prior to the earthquakes with flexible organizational structures and those that emerged after were most successful in the emergency response and early recovery. The ability to capture social cohesion resulting from the shared experience of the earthquakes and build bridges with non-profit connections or incorporate emergent populations into service delivery facilitated successful operations into recovery. Non-profits that partnered with the government were better suited for long-term recovery, when interagency collaboration returned to a more competitive state and reliance on co-production of services was reestablished as the preferred method of service delivery, based on their capacity to maintain and build linkages with civil society partners.
This research adds to disaster literature and the understanding of organizational behaviors by suggesting appropriate means to assess the potential resilience of non-profit organizations post-disaster. Further, pathways of integration with disaster management are identified for various types of non-profits that contribute to sexual health and related community support services. Methods used to identify vulnerabilities of wellbeing focused non-profit organizations and model integration of culturally appropriate service delivery options into recovery planning and disaster mitigation can be applied to other high-income nations with burgeoning non-profit sectors that experience variety of hazards, in particular on the United States’ West Coast as the health care debate in the United States continues.
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Tung, Sui, and 董帥. "Co-seismic and post-seismic gravity variation associated with the 2008 M=8 Wenchuan earthquake : implication for crustal dynamics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197833.
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Longmen Shan Mountain Belt is a prominent orogeny along the eastern margin of the Tibetan plateau. Its current deformation has significant implications for the Cenozoic tectonics of the Tibetan plateau. The M=8 Wenchuan earthquake substantially ruptured the Longmen Shan mountain in 2008. Numerous tectonics and rheological implications are concluded by this event on crustal dynamics along the eastern margin of the Tibetan plateau. Several high-resolution gravity surveys were conducted before and after the event to investigate the regional isostasy and crustal dynamics. From 2008 to 2011, four gravimetric surveys were carried out along two profiles across southern and northern Longmen Shan from the Sichuan Basin to the Songpan-Graze Terrane. The Bouguer gravity anomalies drop from -162 mGal to -431 mGal in the Aba Basin with a steep gradient of 0.84 mGal/km. There is a significant increase of crustal thickness from 40 km in the Sichuan to more than 60 km in the Tibetan plateau.
Negative isostatic anomaly of -30 mGal over 150 km of the Songpan-Graze Terrane infers an over-compensation of excess crustal thickness up to 20 km. Hence, upward isostatic rebound is resulted and coupled with on-going crustal movement. Gravity values change significantly before and after the Wenchuan earthquake, ranging from -1.2 mGal to 0.7 mGal near the epicentral area. Significant thrust slip of 7.5m and normal slip of 4.5 m were simulated along the Beichuan fault and Wenchuan fault by an elastic dislocation theory. The co-existence of thrusting and normal faulting implies both compressional and extensional settings along Longmen Shan. The normal slip corroborates a large-scale crustal extension, lending support to a model with the inflation of lower crustal flow. The two-year post-seismic gravity variations were more than 0.1 mGal near the epicentral area. About 25% of them could be attributed to viscoelastic mantle relaxation. The dynamics topography along the eastern margin of the plateau is proposed to be a consequence of lower crustal flow squeezed by isostatic rebound and topographic load. The strong Yangtze Block is thought to obstruct the crustal flow horizontally and direct it to flow upward beneath Longmen Shan. The steep topography and seismicity along Longmen Shan are then resulted probably from the vertical stress induced in this upward flow.published_or_final_version
Earth Sciences
Doctoral
Doctor of Philosophy
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Cartwright-Taylor, A. L. G. "Deformation-induced electric currents in marble under simulated crustal conditions : non-extensivity, superstatistical dynamics and implications for earthquake hazard." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1471386/.
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This thesis investigates electric current signals generated spontaneously in specimens of Carrara marble during deformation under crustal conditions. It extends previous work where similar currents were observed during uniaxial deformation of marble. Since marble is a non-piezoelectric material, one of the main questions is how these currents are related to the mechanical processes of deformation. Another question is whether it is possible to extract from these electric currents information about the deformation dynamics. This is particularly important in light of recent claims that geoelectric anomalies observed in the field are related to crustal deformation and can inform us about changes in the organisation of the fault network in a focal region prior to an earthquake. Using an approach that combines rock deformation experiments and statistical modelling, I examine how these electric currents evolve with deformation at the laboratory scale and make several original discoveries regarding their behaviour. To establish how the current signals varied with experimental condition and deformation mechanism across the brittle-ductile transition, I conducted constant strain rate triaxial compression experiments recording differential electric current flow through the rock samples at various confining pressures, strain rates and pore fluid conditions. I acquired mechanical data, ultrasonic velocities and acoustic emissions simultaneously, along with electric current, to constrain the relationship between electric current and deformation. For the statistical modelling, I used a novel entropy-based model, derived from non-extensive statistical mechanics (Tsallis, 1988), which has the advantage of including a term to account for interactions in the system. Interactions are effectively modelled by the non-extensive q-parameter. Small (nanoAmpere) electric currents are generated and sustained during deformation under all the conditions tested. Spontaneous electric current flow in the dry samples is seen only in the region of permanent deformation and is due to the presence of localised electric dipoles. This current flow is correlated to the damage induced by microcracking, with a contribution from other intermittent ductile mechanisms. Current and charge densities are consistent with proposed models of crack separation charging and migrating charged edge dislocations. The onset of current flow occurs only after a 10% reduction in P-wave velocity, implying that some degree of crack damage and/or crack connectivity is required before current will flow through the samples. Electric current evolution exhibits three separate time-scales of behaviour, the absolute and fluctuating components of which can be related to the evolution of stress, deformation mechanism, damage and localisation of deformation leading up to sample failure. In the brittle regime, electric current exhibits a precursory change as the stress drop accelerates towards failure, which is particularly distinct at dynamic strain rates. Current and charge production depend strongly on the experimental conditions. Power-law relationships are seen with confining pressure and strain rate, with the first corresponding to increased microcrack suppression and the second to time-dependent differences in deformation mechanism across the brittle-ductile transition. In the presence of an ionic pore fluid, electrokinetic effects dominate over solid-state mechanisms but development of the crack network and charge contribution from solid-state deformation processes drive the variation in electrokinetic parameters. Current flow in the dry samples is approximately proportional to stress within 90% of peak stress. In the fluid-saturated samples, proportionality holds from 40% peak stress, with a significant increase in the rate of current production from 90% peak stress, and is associated with fluid flow during dilatancy. This proportionality, together with the power-law relationship between current and strain rate is reminiscent of power-law creep, where deformation rate varies as a power-law function of stress, and suggests that the electric signals could be used as a proxy for stress. High frequency fluctuations in the electric current signal can be described by `fat-tailed' q-Gaussian statistics, consistent with an origin in non-extensive statistical mechanics. These distributions can be explained as arising from superstatistical dynamics (Beck, 2001; Beck and Cohen, 2003), i.e., the superposition of local mechanical relaxations in the presence of a slowly varying driving force. The macroscopic distribution parameters provide an excellent prediction of the experimentally observed mean energy dissipation rate of the system (as modelled by the superstatistical β-parameter), particularly at slow strain rates. Furthermore, characteristic q-values are obtained for different deformation regimes across the brittle-ductile transition, and the evolution of q during deformation reveals a two-stage precursory anomaly prior to sample failure, consistent with the stress intensity evolution as modelled from fracture mechanics. These findings indicate that the dynamics of rock deformation are reflected in the statistical properties of the recorded electric current. My findings support the notion that electric currents in the crust can be generated purely from deformation processes themselves. Scaling up the laboratory results to large stressed rock volumes at shallow crustal pressures and constant crustal strain rates, deformation induced transient telluric current systems may be as large as 1 MA, even accounting for >99% dissipation, which corresponds to a huge accumulated net charge of 10 ZC. This implies that a significant amount of charge from deforming tectonic regions contributes to the Earth's telluric currents and electric field, although due to conduction away from the stressed rock volume, it is unlikely that accumulated charge of this quantity would ever be measured in the field. Electric current evolution and its precursory characteristics can be related to models for electric earthquake precursors and fault-zone damage organisation, developed from field observations, providing experimental support for them. However, given the oscillatory nature of the current evolution observed during cataclastic flow processes in the laboratory, there is a high probability of false alarms. Furthermore, the potential for electric anomalies to be useful as earthquake precursors remains contentious due to the difficulties of separating deformation-induced signals from other telluric noise and the wider issue of establishing a statistically significant link with earthquakes.
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Eisenbeis, Julian. "Ionospheric Dynamics by GNSS total electron content observations : the effect of Solar Eclipses and the mystery of Earthquake precursors." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7027.
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Cette thèse porte principalement sur deux sujets: l'un est la signature ionosphérique des éclipses solaires, l'autre est le débat ‘Hole vs Enhancement’. Le 21 août 2017, l'ombre d'une éclipse totale a changé radicalement l'état de l'ionosphère au-dessus des Etats-Unis. Cet effet est visible dans le contenu total en électrons (TEC) mesuré par ~3000 stations GNSS qui voient des multiples satellites GPS et GLONASS. Ce formidable ensemble de données permet une caractérisation à haute résolution du contenu en fréquences et des longueurs d'onde - en utilisant une analyse omega-k basée sur la Transformée de Fourier Rapide (FFT) 3D - de la signature de l'éclipse dans l'ionosphère afin d'identifier complètement les perturbations ionosphériques mobiles (TID). Nous confirmons la génération de TIDs associées à l'éclipse, y compris les TIDs interprétées comme des ondes de proue dans les études précédentes. De plus, nous révélons, pour la première fois, des TID de courte (50-100 km) et de longue (500-600 km) longueurs d'onde avec des périodes entre 30 et 65 min (Eisenbeis et al., 2019). Le 2 juillet 2019, une autre éclipse solaire totale s'est produite à travers le continent sud-américain. Bien que nous n'ayons que des données provenant de plus de cent stations GNSS et situées dans une zone proche du coucher du soleil, nous pouvons montrer la preuve évidente de la signature ionosphérique de l'éclipse (Eisenbeis & Occhipinti in prep.a). Le deuxième grand sujet de ce travail est le débat sur la possibilité de précurseurs de séismes. Heki (2011) a suscité ce débat en publiant les résultats du séisme de Tohoku montrant une amélioration de la TEC avant le séisme. L'amélioration revendiquée par Heki (2011) a été interprétée comme une diminution de la TEC après l'événement, le soi-disant trou ionosphérique dans la littérature. L'existence de l'amélioration a été promue par plusieurs articles (e.g. He & Heki, 2017) étendant l'observation à plusieurs événements de magnitude modérée (M> 7.5) et propose une nouvelle vision de la dynamique de rupture. En essayant de reproduire leurs résultats, nous montrons que la courbe de référence utilisée par Heki (2011) est affectée par l'ordre d'ajustement polynomial ainsi que par les fenêtres temporelles sélectionnées. Ceci montre que l'amélioration du TEC pourrait en fait n'être qu'un artefact, subjectivement sélectionné pour créer le précurseur présumé (Eisenbeis & Occhipinti in prep.b)This thesis focuses mainly on two topics: one is the ionospheric signature of solar eclipses, the second is the Hole vs Enhancement debate about earthquake precursors. On the 21st August 2017 the shadow of a total eclipse drastically changed the state of the ionosphere over the USA. This effect is visible in the total electron content (TEC) measured by ~3000 GNSS stations seeing multiple GPS and GLONASS satellites. This tremendous dataset allows high-resolution characterization of the frequency content and wavelengths -using an omega-k analysis based on 3D Fast-Fourier-Transform (FFT)- of the eclipse signature in the ionosphere in order to fully identify traveling ionospheric disturbances (TIDs). We confirm the generation of TIDs associated with the eclipse including TIDs interpreted as bow waves in previous studies. Additionally we reveal, for the first time, short (50-100 km) and long (500-600 km) wavelength TIDs with periods between 30 and 65 min (Eisenbeis et al., 2019). On 2nd July 2019 another total solar eclipse happened across the South American continent at magnetic conjugate latitudes as the Great American Eclipse, and consequently useful to visualize the difference response. Although for the South American eclipse we have only data from more than hundred GNSS stations and located in a zone close to the sunset, we can show the clear evidence of the ionospheric signature of the eclipse (Eisenbeis & Occhipinti in prep.a).The second major topic in this work is the still ongoing debate about the possibility of earthquake precursors. Heki (2011) sparked this debate when he published results of the Tohoku earthquake showing a TEC enhancement before the earthquake. The enhancement claimed by Heki (2011) has been interpreted as a decrease in the background TEC after the seismic event, the so called ionospheric hole in literature. The existence of the enhancement has been promoted by several papers (e.g. He & Heki, 2017) extending the observation to several events with moderate magnitude (M> 7.5) and proposes a new vision of the rupture dynamics. By trying to reproduce their results we show that the reference curve used by Heki (2011) to define the TEC background is strongly affected by the order of polynomial fit as well as the selected time windows. This shows that the TEC enhancement could be, in fact, just an artifact, subjectively selected to create the presumed precursor (Eisenbeis & Occhipinti in prep.b)
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Balendra, Surendran. "Numerical modeling of dynamic soil-pile-structure interaction." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/s%5Fbalendra%5F120705.pdf.
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Gregg, Patricia Michelle Marie. "The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45779.
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Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008.Includes bibliographical references.
Segmentation and crustal accretion at oceanic transform fault systems are investigated through a combination of geophysical data analysis and geodynamical and geochemical modeling. Chapter 1 examines the effect of fault segmentation on the maximum predicted earthquake magnitude of an oceanic transform fault system. Results of thermal modeling suggest that fault segmentation by intra- transform spreading centers (ITSC) drastically reduces the available brittle area of a transform fault and thus limits the available earthquake rupture area. Coulomb stress models suggest that long ITSCs will prohibit static stress interaction between segments of a transform system and further limit the maximum possible magnitude of a given transform fault earthquake. In Chapter 2, gravity anomalies from a global set of oceanic transform fault systems are investigated. Surprisingly, negative residual mantle Bouguer gravity anomalies are found within fast-slipping transform fault domains. These gravity observations suggest a mass deficit within fast-slipping transform faults, which may result from porosity variations, mantle serpentinization, and/or crustal thickness variations. Two-dimensional forward modeling and the correlation of the negative gravity anomalies to bathymetric highs indicate crustal thickness excesses in these locations. Finally, in Chapter 3, mantle thermal and melting models for a visco-plastic rheology are developed to investigate the process of mantle melting and crustal accretion at ITSCs within segmented transform faults, and are applied to the Siqueiros transform fault system. Models in which melt migrates into the transform fault domain from a large region of the mantle best explain the gravity-derived crustal thickness variations observed at the Siqueiros transform. Furthermore, a mantle potential temperature of 1350⁰C and fractional crystallization at depths of 9 - 15.5 km best explain the major element composition variation observed at the Siqueiros transform.
by Patricia Michelle Marie Gregg.
Ph.D.
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Liao, Tianfei. "Post processing of cone penetration data for assessing seismic ground hazards, with application to the New Madrid seismic zone." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-05042005-133640/.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.Mayne, Paul W., Committee Chair ; Goldsman, David, Committee Member ; Lai, James, Committee Member ; Rix, Glenn J., Committee Member ; Santamarina, J. Carlos, Committee Member.
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Hunt, Stephen J. "Semi-active smart-dampers and resetable actuators for multi-level seismic hazard mitigation of steel moment resisting frames." Thesis, University of Canterbury. Mechanical Engineering, 2002. http://hdl.handle.net/10092/1256.
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This thesis explores the creation and assessment of semi-active control algorithms for both squat shear buildings and tall flexible structures. If cost-effective, practicable, semi-active structural control systems can be developed, the potential reduction in loss of both property and lives due to seismic events is significant. Semi-active controllers offer many of the benefits of active systems, but have power requirements orders of magnitude smaller, and do not introduce energy to the structural system. Previous research into semi-active controllers has shown their potential in linear simulations with single earthquake excitations. The distinguishing feature of this investigation is the use of appropriate non-linear modelling techniques and realistic suites of seismic excitations in the statistical assessment of the semi-active control systems developed. Finite element time-history analysis techniques are used in the performance assessment of the control algorithms developed for three and nine story structural models. The models include non-linear effects due to structural plasticity, yielding, hysteretic behaviour, and P-delta effects. Realistic suites of earthquake records, representing seismic excitations with specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. In addition to displacement focused control laws, acceleration and jerk regulation control methods are developed, showing that potential damage reduction benefits can be obtained from these new control approaches. A statistical assessment of control architecture is developed and undertaken, examining the distribution of constant maximum actuator authority for both squat shear buildings, and tall slender structures, highlighting the need to consider non-linear structural response characteristics when implementing semi-active control systems. Finally, statistical analysis of all results and normalised values shows the efficacy of each control law and actuator type relative to different magnitude seismic events. As a result, this research clearly presents, for the first time, explicit tradeoffs between control law, architecture type, non-linear structural effects, and seismic input characteristics for the semi-active control of civil structures.
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Bleichner, Noah G. "A Comparative Study on Seismic Analysis Methods and the Response of Systems with Classical and Nonclassical Damping." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2219.
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This thesis investigated the application of seismic analysis methods and the response of idealized shear frames subjected to seismic loading. To complete this research, a Design Basis Earthquake (DBE) for a project site in San Luis Obispo, CA, and five past earthquake records were considered. The DBE was produced per the American Society of Civil Engineers’ Minimum Design Loads for Buildings and Other Structures (ASCE 7-10) and used for application of the Equivalent Lateral Force Procedure (ELFP) and Response Spectrum Analysis (RSA). When applying RSA, the modal peak responses were combined using the Absolute Sum (ABS), Square-Root-of-the-Sum-of-Squares (SRSS), and Complete Quadratic Combination (CQC) method.
MATLAB scripts were developed to produce several displacement, velocity, and acceleration spectrums for each earthquake. Moreover, MATLAB scripts were written to yield both analytical and numerical solutions for each system through application of Linear Time History Analysis (THA). To obtain analytical solutions, two implicit forms of the Newmark-beta Method were employed: the Average Acceleration Method and the Linear Acceleration Method.
To generate a comparison, the ELFP, RSA, and THA methods were applied to shear frames up to ten stories in height. The system parameters that impacted the accuracy of each method and the response of the systems were analyzed, including the effects of classical damping and nonclassical damping models. In addition to varying levels of Rayleigh damping, non-linear hysteric friction spring dampers (FSDs) were implemented into the systems. The design of the FSDs was based on target stiffness values, which were defined as portions of the system’s lateral stiffness. To perform the required Nonlinear Time History Analysis (NTHA), a SAP2000 model was developed. The efficiencies of the FSDs at each target stiffness, with and without the addition of low levels of viscous modal damping are analyzed.
It was concluded that the ELFP should be supplemented by RSA when performing seismic response analysis. Regardless of system parameters, the ELFP yielded system responses 30% to 50% higher than RSA when combing responses with the SRSS or CQC method. When applying RSA, the ABS method produced inconsistent and inaccurate results, whereas the SRSS and CQC results were similar for regular, symmetric systems. Generally, the SRSS and CQC results were within 5% of the analytical solution yielded through THA. On the contrary, for irregular structures, the SRSS method significantly underestimated the response, and the CQC method was four to five times more accurate. Additionally, both the Average Acceleration Method and Linear Acceleration Method yielded numerical solutions with errors typically below 1% when compared with the analytical solution.
When implemented into the systems, the FSDs proved to be most efficient when designed to have stiffnesses that were 50% of the lateral stiffness of each story. The addition of 1% modal damping to the FSDs resulted in quicker energy dissipation without significantly reducing the peak response of the system. At a stiffness of 50%, the FSDs reduced the displacement response by 40% to 60% when compared with 5% modal damping. Additionally, the FSDs at low stiffnesses exhibited the effects of negative lateral stiffness due to P-delta effects when the earthquake ground motions were too weak to induce sliding in the ring assemblies.
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Wu, Chunquan. "Fault zone damage, nonlinear site response, and dynamic triggering associated with seismic waves." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41143.
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My dissertation focuses primarily on the following three aspects associated with passing seismic waves in the field of earthquake seismology: temporal changes of fault zone properties, nonlinear site response, and dynamic triggering.
Quantifying the temporal changes of material properties within and around active fault zones (FZ) is important for better understanding of rock rheology and estimating the strong ground motion that can be generated by large earthquakes. As high-amplitude seismic waves propagate through damaged FZ rocks and/or shallow surface layers, they may produce additional damage leading to nonlinear wave propagation effects and temporal changes of material properties (e.g., seismic velocity, attenuation). Previous studies have found several types of temporal changes in material properties with time scales of tens of seconds to several years. Here I systematically analyze temporal changes of fault zone (FZ) site response along the Karadere-Düzce branch of the North Anatolian fault that ruptured during the 1999 İzmit and Düzce earthquake sequences. The coseismic changes are on the order of 20-40%, and are followed by a logarithmic recovery over an apparent time scale of ~1 day. These results provide a bridge between the large-amplitude near-instantaneous changes and the lower-amplitude longer-duration variations observed in previous studies. The temporal changes measured from this high-resolution spectral ratio analysis also provide a refinement for the beginning of the longer more gradual process typically observed by analyzing repeating earthquakes.
An improved knowledge on nonlinear site response is critical for better understanding strong ground motions and predicting shaking induced damages. I use the same sliding-window spectral ratio technique to analyze temporal changes in site response associated with the strong ground motion of the Mw6.6 2004 Mid-Niigata earthquake sequence recorded by the borehole stations in Japanese Digital Strong-Motion Seismograph Network (KiK-Net). The coseismic peak frequency drop, peak spectral ratio drop, and the postseismic recovery time roughly scale with the input ground motions when the peak ground velocity (PGV) is larger than ~5 cm/s, or the peak ground acceleration (PGA) is larger than ~100 Gal. The results suggest that at a given site the input ground motion plays an important role in controlling both the coseismic change and postseismic recovery in site response.
In a follow-up study, I apply the same sliding-window spectral ratio technique to surface and borehole strong motion records at 6 KiK-Net sites, and stack results associated with different earthquakes that produce similar PGAs. In some cases I observe a weak coseismic drop in the peak frequency when the PGA is as small as ~20-30 Gal, and near instantaneous recovery after the passage of the direct S waves. The percentage of drop in the peak frequency starts to increase with increasing PGA values. A coseismic drop in the peak spectral ratio is also observed at 2 sites. When the PGA is larger than ~60 Gal to more than 100 Gal, considerably stronger coseismic drops of the peak frequencies are observed, followed by a logarithmic recovery with time. The observed weak reductions of peak frequencies with near instantaneous recovery likely reflect nonlinear response with essentially fixed level of damage, while the larger drops followed by logarithmic recovery reflect the generation (and then recovery) of additional rock damage. The results indicate clearly that nonlinear site response may occur during medium-size earthquakes, and that the PGA threshold for in situ nonlinear site response is lower than the previously thought value of ~100-200 Gal.
The recent Mw9.0 off the Pacific coast of Tohoku earthquake and its aftershocks generated widespread strong shakings as large as ~3000 Gal along the east coast of Japan. I systematically analyze temporal changes of material properties and nonlinear site response in the shallow crust associated with the Tohoku main shock, using seismic data recorded by the Japanese Strong Motion Network KIK-Net. I compute the spectral ratios of windowed records from a pair of surface and borehole stations, and then use the sliding-window spectral ratios to track the temporal changes in the site response of various sites at different levels of PGA The preliminary results show clear drop of resonant frequency of up to 70% during the Tohoku main shock at 6 sites with PGA from 600 to 1300 Gal. In the site MYGH04 where two distinct groups of strong ground motions were recorded, the resonant frequency briefly recovers in between, and then followed by an apparent logarithmic recovery. I investigate the percentage drop of peak frequency and peak spectral ratio during the Tohoku main shock at different PGA levels, and find that at most sites they are correlated.
The third part of my thesis mostly focuses on how seismic waves trigger additional earthquakes at long-range distance, also known as dynamic triggering. Previous studies have shown that dynamic triggering in intraplate regions is typically not as common as at plate-boundary regions. Here I perform a comprehensive analysis of dynamic triggering around the Babaoshan and Huangzhuang-Gaoliying faults southwest of Beijing, China. The triggered earthquakes are identified as impulsive seismic arrivals with clear P- and S-waves in 5 Hz high-pass-filtered three-component velocity seismograms during the passage of large amplitude body and surface waves of large teleseismic earthquakes. I find that this region was repeatedly triggered by at least four earthquakes in East Asia, including the 2001 Mw7.8 Kunlun, 2003 Mw8.3 Tokachi-oki, 2004 Mw9.2 Sumatra, and 2008 Mw7.9 Wenchuan earthquakes. In most instances, the microearthquakes coincide with the first few cycles of the Love waves, and more are triggered during the large-amplitude Rayleigh waves. Such an instantaneous triggering by both the Love and Rayleigh waves is similar to recent observations of remotely triggered 'non-volcanic' tremor along major plate-boundary faults, and can be explained by a simple Coulomb failure criterion. Five earthquakes triggered by the Kunlun and Tokachi-oki earthquakes were recorded by multiple stations and could be located. These events occurred at shallow depth (< 5 km) above the background seismicity near the boundary between NW-striking Babaoshan and Huangzhuang-Gaoliying faults and the Fangshan Pluton. These results suggest that triggered earthquakes in this region likely occur near the transition between the velocity strengthening and weakening zones in the top few kms of the crust, and are likely driven by relatively large dynamic stresses on the order of few tens of KPa.
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Madabhushi, Srikanth Satyanarayana Chakrapani. "Multi-hazard modelling of dual row retaining walls." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/288604.
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The recent 2011 Tōhoku earthquake and tsunami served as a stark reminder of the destructive capabilities of such combined events. Civil Engineers are increasingly tasked with protecting coastal populations and infrastructure against more severe multi-hazard events. Whilst the protective measures must be robust, their deployment over long stretches of coastline necessitates an economical and environmentally friendly design. The dual row retaining wall concept, which features two parallel sheet pile walls with a sand infill between them and tie rods connecting the wall heads, is potentially an efficient and resilient system in the face of both earthquake and tsunami loading. Optimal use of the soil's strength and stiffness as part of the structural system is an elegant geotechnical solution which could also be applied to harbours or elevated roads. However, both the static equilibrium and dynamic response of these types of constructions are not well understood and raise many academic and practical challenges. A combination of centrifuge and numerical modelling was utilised to investigate the problem. Studying the mechanics of the walls in dry sand from the soil stresses to the system displacements revealed the complex nature of the soil structure interaction. Increased wall flexibility can allow more utilisation of the soil's plastic capacity without necessarily increasing the total displacements. Recognising the dynamically varying vertical effective stresses promotes a purer understanding of the earth pressures mobilised around the walls and may encourage a move away from historically used dynamic earth pressure coefficients. In a similar vein, the proposed modified Winkler method can form the basis of an efficient preliminary design tool for practice with a reduced disconnect between the wall movements and mobilised soil stresses. When founded in liquefiable soil and subjected to harmonic base motion, the dual row walls were resilient to catastrophic collapse and only accrued deformation in a ratcheting fashion. The experiments and numerical simulations highlighted the importance of relative suction between the walls, shear-induced dilation and regained strength outside the walls and partial drainage in the co-seismic period. The use of surrogate modelling to automatically optimise parameter selection for the advanced constitutive model was successfully explored. Ultimately, focussing on the mechanics of the dual row walls has helped further the academic and practical understanding of these complex but life-saving systems.
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Sullivan, Brendan. "Delayed triggering of early aftershocks by multiple surface waves circling the earth." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45827.
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It is well known that direct surface waves of large earthquakes are capable of triggering shallow earthquakes and deep tremor at long-range distances. Recent studies have shown that multiple surface waves circling the earth could also remotely trigger microearthquakes. However, it is still not clear whether multiple surface waves returning back to the main shock epicenters could also trigger/modulate aftershock behavior. Here we conduct a study to search for evidence of such triggering by systematically examining aftershock patterns of earthquakes with magnitude ≥ 8 since 1990 that produce observable surface waves circling the globe repeatedly. We specifically examine the 2011 M9 Tohoku-Oki event using a composite catalog of JMA, HiNet and newly detected events obtained by waveform cross correlation. We compute the magnitude of completeness for each sequence, and stack all the sequences together to compute the seismicity and moment rates by sliding data windows. The sequences are also shuffled randomly and these rates are compared to the actual data as well as synthetic aftershock sequences to estimate the statistical significance of the results. Our results suggest that there is some moderate increase of early aftershock activity after a few hours when the surface waves return to the epicentral region. However, we could not completely rule out the possibility that such an increase is purely due to random fluctuations of aftershocks or caused by missing aftershocks in the first few hours after the mainshock.
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Park, Joonam. "Development and Application of Probabilistic Decision Support Framework for Seismic Rehabilitation of Structural Systems." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4898.
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Seismic rehabilitation of structural systems is an effective approach for reducing potential seismic losses such as social and economic losses. However, little or no effort has been made to develop a framework for making decisions on seismic rehabilitation of structural systems that systematically incorporates conflicting multiple criteria and uncertainties inherent in the seismic hazard and in the systems themselves.
This study develops a decision support framework for seismic rehabilitation of structural systems incorporating uncertainties inherent in both the system and the seismic hazard, and demonstrates its application with detailed examples. The decision support framework developed utilizes the HAZUS method for a quick and extensive estimation of seismic losses associated with structural systems. The decision support framework allows consideration of multiple decision attributes associated with seismic losses, and multiple alternative seismic rehabilitation schemes represented by the objective performance level. Three multi-criteria decision models (MCDM) that are known to be effective for decision problems under uncertainty are employed and their applicability for decision analyses in seismic rehabilitation is investigated. These models are Equivalent Cost Analysis (ECA), Multi-Attribute Utility Theory (MAUT), and Joint Probability Decision Making (JPDM). Guidelines for selection of a MCDM that is appropriate for a given decision problem are provided to establish a flexible decision support system. The resulting decision support framework is applied to a test bed system that consists of six hospitals located in the Memphis, Tennessee, area to demonstrate its capabilities.
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Gutierrez, Soto Mariantonieta. "MULTI-AGENT REPLICATOR CONTROL METHODOLOGIES FOR SUSTAINABLE VIBRATION CONTROL OF SMART BUILDING AND BRIDGE STRUCTURES." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494249419696286.
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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.
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La surveillance de la réponse structurale est fondamentale pour estimer la performance des bâtiments et réduire les pertes lors de futurs séismes. Un moyen pratique de détecter les changements de comportement structural consiste à analyser les variations des propriétés élastiques lors d'excitations dynamiques. Dans ce travail, on montre que les variations de la fréquence fondamentale des bâtiments lors de tremblements de terre (faibles à forts) pourraient être expliquées par des processus élastiques non linéaires qui se produisent à l'intérieur du matériau, et qui finalement affectent le comportement macroscopique global des bâtiments. Ces processus élastiques non linéaires sont responsables de la diminution temporaire ou permanente de la rigidité structurale, pouvant expliquer les processus de récupération des propriétés élastiques observés à la suite d'événements sismiques. Cette étude comble le fossé entre des expériences de laboratoire à l'échelle microscopique et des observations sismologiques à l'échelle macroscopique, où l’élasticité non linéaire est également observée. Dans un premier temps, une base de données sismiques établie dans le cadre de cette thèse est présentée, incluant des réponses de bâtiments instrumentés de façon permanente dans le monde: des milliers d’enregistrements de mouvements sismiques et plusieurs bâtiments du Japon et des États-Unis ont été traités, apportant des connaissances utiles pour le domaine du génie parasismique, notamment pour la prédiction empirique de la réponse structurale en fonction de mesures d'intensité du mouvement au sol. Les incertitudes associées à la prédiction d’endommagement sont présentées, ainsi que l'évaluation de la vulnérabilité d'un bâtiment sous forme de courbes de fragilité. Ensuite, la base de données est utilisée pour analyser les signatures élastiques non linéaires dans les bâtiments, en particulier les effets de la dynamique lente (ou relaxation). Les variations des fréquences de résonance sont étudiées à court et à long terme, en estimant la contribution du sol à la réponse du système sol-structure. Différents états structuraux sont déduits en fonction des amplitudes de chargement et propriétés observées via les enregistrements. Des modèles de relaxation développés en laboratoire sont ensuite adaptés aux données des bâtiments afin de caractériser la densité de fissuration et les hétérogénéités, en effectuant des comparaisons entre les états structuraux avant et après de fortes excitations telles que le séisme de 2011 (Mw=9) de Tohoku (Japon). Les effets des chargements sont observés lors de la récupération des séquences de répliques. Les résultats sont étendus à différentes typologies de bâtiments, en analysant l'influence du matériau et des caractéristiques de chargement, notamment les taux de déformation. Enfin, quelques conclusions générales sont présentées, ainsi qu'une perspective de travail utilisant des outils de machine learning pour prédire la réponse de bâtiments en fonction de signatures élastiques non linéaires observéesMonitoring 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
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Rishi, Ram Parajuli. "DYNAMIC BEHAVIOR OF VEHICLES DURING AN EARTHQUAKE." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225571.
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Selva, Francesco. "Seismic performance of rooftop cooling towers in buildings." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4884/.
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Negli ultimi anni la ricerca ha fatto grandi passi avanti riguardo ai metodi di progetto e realizzazione delle strutture portanti degli edifici, a tal punto da renderle fortemente sicure sotto tutti i punti di vista. La nuova frontiera della ricerca sta quindi virando su aspetti che non erano mai stati in primo piano finora: gli elementi non-strutturali. Considerati fino ad oggi semplicemente carico accessorio, ci si rende sempre più conto della loro capacità di influire sui comportamenti delle strutture e sulla sicurezza di chi le occupa. Da qui nasce l’esigenza di questo grande progetto chiamato BNCs (Building Non-structural Component System), ideato dall’Università della California - San Diego e sponsorizzato dalle maggiori industrie impegnate nel campo delle costruzioni. Questo progetto, a cui ho preso parte, ha effettuato test su tavola vibrante di un edificio di cinque piani in scala reale, completamente arredato ed allestito dei più svariati elementi non-strutturali. Lo scopo della tesi in questione, ovviamente, riguarda l’identificazione strutturale e la verifica della sicurezza di uno di questi elementi non-strutturali: precisamente la torre di raffreddamento posta sul tetto dell’edificio (del peso di circa 3 tonnellate). Partendo da una verifica delle regole e calcoli di progetto, si è passato ad una fase di test sismici ed ispezioni post-test della torre stessa, infine tramite l’analisi dei dati raccolti durante i test e si è arrivati alla stesura di conclusioni.
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Kasinos, Stavros. "Seismic response analysis of linear and nonlinear secondary structures." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33728.
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Understanding the complex dynamics that underpin the response of structures in the occurrence of earthquakes is of paramount importance in ensuring community resilience. The operational continuity of structures is influenced by the performance of nonstructural components, also known as secondary structures. Inherent vulnerability characteristics, nonlinearities and uncertainties in their properties or in the excitation pose challenges that render their response determination as a non-straightforward task. This dissertation settles in the context of mathematical modelling and response quantification of seismically driven secondary systems. The case of bilinear hysteretic, rigid-plastic and free-standing rocking oscillators is first considered, as a representative class of secondary systems of distinct behaviour excited at a single point in the primary structure. The equations governing their full dynamic interaction with linear primary oscillators are derived with the purpose of assessing the appropriateness of simplified analysis methods where the secondary-primary feedback action is not accounted for. Analyses carried out in presence of pulse-type excitation have shown that the cascade approximation can be considered satisfactory for bilinear systems provided the secondary-primary mass ratio is adequately low and the system does not approach resonance. For the case of sliding and rocking systems, much lighter secondary systems need to be considered if the cascade analysis is to be adopted, with the validity of the approximation dictated by the selection of the input parameters. Based on the premise that decoupling is permitted, new analytical solutions are derived for the pulse driven nonlinear oscillators considered, conveniently expressing the seismic response as a function of the input parameters and the relative effects are quantified. An efficient numerical scheme for a general-type of excitation is also presented and is used in conjunction with an existing nonstationary stochastic far-field ground motion model to determine the seismic response spectra for the secondary oscillators at given site and earthquake characteristics. Prompted by the presence of uncertainty in the primary structure, and in line with the classical modal analysis, a novel approach for directly characterising uncertainty in the modal shapes, frequencies and damping ratios of the primary structure is proposed. A procedure is then presented for the identification of the model parameters and demonstrated with an application to linear steel frames with uncertain semi-rigid connections. It is shown that the proposed approach reduces the number of the uncertain input parameters and the size of the dynamic problem, and is thus particularly appealing for the stochastic assessment of existing structural systems, where partial modal information is available e.g. through operational modal analysis testing. Through a numerical example, the relative effect of stochasticity in a bi-directional seismic input is found to have a more prominent role on the nonlinear response of secondary oscillators when compared to the uncertainty in the primary structure. Further extending the analyses to the case of multi-attached linear secondary systems driven by deterministic seismic excitation, a convenient variant of the component-mode synthesis method is presented, whereby the primary-secondary dynamic interaction is accounted for through the modes of vibration of the two components. The problem of selecting the vibrational modes to be retained in analysis is then addressed for the case of secondary structures, which may possess numerous low frequency modes with negligible mass, and a modal correction method is adopted in view of the application for seismic analysis. The influence of various approaches to build the viscous damping matrix of the primary-secondary assembly is also investigated, and a novel technique based on modal damping superposition is proposed. Numerical applications are demonstrated through a piping secondary system multi-connected on a primary frame exhibiting various irregularities in plan and elevation, as well as a multi-connected flexible secondary system. Overall, this PhD thesis delivers new insights into the determination and understanding of the response of seismically driven secondary structures. The research is deemed to be of academic and professional engineering interest spanning several areas including seismic engineering, extreme events, structural health monitoring, risk mitigation and reliability analysis.
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Zhuge, Yan. "Nonlinear dynamic response of unreinforced masonry under in-plane lateral loads." Thesis, Queensland University of Technology, 1995.
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Brietzke, Gilbert Björn. "Dynamic Earthquake Ruptures in the Presence of Material Discontinuities." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-102234.
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Amundsen, Morten. "Dynamic Analysis of Offshore Concrete Structures subjected to Earthquake." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19005.
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This thesis attempts to study the dynamic response of offshore concrete structures by sequentially introducing physical phenomena which are related to those types of analyses. This is done by modelling a simplified part of a typical offshore concrete structure, with the purpose of establishing a reference case, on which more advanced analyses can be based, as well as evaluate simplified approaches that serve to shorten the analysis time.To establish characteristic earthquakes for the selected return periods of 475, 1000, 3000 and 10 000 years, a seismic hazard analysis is performed for an area slightly off the southwest coast of Norway. Here, information from 964 earthquakes was collected, such that the Gutenberg-Richter relationship could be established. Based on this, 50 000 earthquakes were generated based on Monte Carlo simulations, which served as an extrapolation from which order statistics could be performed. The determined characteristic earthquake parameters for the different return periods were found to have a remarkable similarity with the seismic zonation maps used in most design codes. Finally, the applied accelerogram for a given return period was simulated from a response spectrum which was chosen to be similar to the mean response spectrum for that return period.A comparison was made between the time history and response spectrum analysis, where three modal combination methods were evaluated. It was found that the results were either impractically conservative, or dangerously unconservative for all return periods, suggesting that the response spectrum analysis is not applicable for the investigated structure.A material model which included plasticity was evaluated, which resulted in margin-ally lower stresses, slightly reduced eigenfrequencies and small changes displacements of the top of the shaft. With the inclusion of elastic stiffness degradation, the results were similar, leading to the conclusion that plasticity is an unnecessary complication, as the large dimensions of the structure combined with the low seismicity of the North Sea results in a structural behaviour which is approximately elastic for all return periods.Two methods for the modelling of surrounding water was tested. The first was the added mass method, where the stresses mostly increased, except for the 10 000-year earthquake. The second method was an acoustic-structural interaction, where the fluid around the structure was modelled. This resulted in similar stresses for all return periods, and gives credibility to the simplified method. For either methods, the eigenfrequencies were reduced significantly.The soil upon which the structure rests was included into the analysis by two methods. The first method involved the use of springs and dashpots which were made to represent the stiffness and damping of the soil. The other method was a finite element analysis of the soil layer. Both soft and hard soil was tested, and for the soft soil, the stresses were radically reduced, as the structure became almost fully isolated from the earthquake. The stiffer soil resulted in higher stresses. The two methods agreed for the soft soil, but not for the hard soil. This was found to be caused by the spring method being overly simplistic.
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Majid, Taksiah A. "Structural pounding of an adjacent building under dynamic loading." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263904.
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Twardzik, Cedric. "Study of the earthquake source process and seismic hazards." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c2553a3f-f6ce-46a0-9c47-d68f5957cdac.
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To obtain the rupture history of the Parkfield, California, earthquake, we perform 12 kinematic inversions using elliptical sub-faults. The preferred model has a seismic moment of 1.21 x 10^18 Nm, distributed on two distinct ellipses. The average rupture speed is ~2.7 km/s. The good spatial agreement with previous large earthquakes and aftershocks in the region, suggests the presence of permanent asperities that break during large earthquakes. We investigate our inversion method with several tests. We demonstrate its capability to retrieve the rupture process. We show that the convergence of the inversion is controlled by the space-time location of the rupture front. Additional inversions show that our procedure is not highly influenced by high-frequency signal, while we observe high sensitivity to the waveforms duration. After considering kinematic inversion, we present a full dynamic inversion for the Parkfield earthquake using elliptical sub-faults. The best fitting model has a seismic moment of 1.18 x 10^18 Nm, distributed on one ellipse. The rupture speed is ~2.8 km/s. Inside the parameter-space, the models are distributed according the rupture speed and final seismic moment, defining a optimal region where models fit correctly the data. Furthermore, to make the preferred kinematic model both dynamically correct while fitting the data, we show it is necessary to connect the two ellipses. This is done by adopting a new approach that uses b-spline curves. Finally, we relocate earthquakes in the vicinity of the Darfield, New-Zealand earthquake. 40 years prior to the earthquake, where there is the possibility of earthquake migration towards its epicentral region. Once it triggers the 2010-2011 earthquake sequence, we observe earthquakes migrating inside regions of stress increase. We also observe a stress increase on a large seismic gap of the Alpine Fault, as well as on some portions of the Canterbury Plains that remain today seismically quiet.