Literatura científica selecionada sobre o tema "Seismic cycles"
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Artigos de revistas sobre o assunto "Seismic cycles"
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Cui, Fengkun, Linlin Song, Xingyu Wang, Mian Li, Peng Hu, Shuwen Deng, Xinyue Zhang e Huihui Li. "Seismic Fragility Analysis of the Aging RC Columns under the Combined Action of Freeze–Thaw Cycles and Chloride-Induced Corrosion". Buildings 12, n.º 12 (14 de dezembro de 2022): 2223. http://dx.doi.org/10.3390/buildings12122223.
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The combined action of freeze–thaw cycles and chloride-induced corrosion are generally recognized as one of the main causes of the degradation of the mechanical properties and seismic performance of reinforced concrete (RC) structures in the northern frozen coastal regions. To investigate the degradation mechanisms of the seismic performance of RC columns subjected to the combined action of freeze–thaw cycles and chloride-induced corrosion, the impact of freeze–thaw cycles on the chloride diffusion coefficient of concrete was studied through concrete deterioration tests and theoretical analysis. This paper proposed a time-dependent deterioration model for RC columns, which is suitable to consider the combined action of freeze–thaw cycles and chloride-induced deterioration. The proposed deterioration model could be applied to the investigations of time-dependent seismic performance and the seismic fragility of RC columns. Based on the established deterioration model, this paper proposed a time-dependent seismic fragility analysis framework for the aging RC columns, considering the combined action of freeze–thaw cycles and chloride-induced corrosion. In addition, a representative three-span RC continuous T-shaped girder bridge that is located in the high-latitude northern frozen coastal regions of China was taken as the case study, and the time-dependent seismic fragility analysis of RC columns was conducted considering the involved uncertainties in geometric parameters, the deterioration mechanisms of the materials, and ground motions. The time-dependent seismic fragility curves of RC columns were obtained at different service time points. The results indicated that the combined action of freeze–thaw cycles and chloride-induced deterioration had a significant influence on the time-dependent seismic responses of the deteriorating RC columns. Under the combined action of freeze–thaw cycles and chloride-induced corrosion, when the RC bridge was in service for 75 years, the stirrup strength decreased by 3.88% and the cross-sectional area decreased by 30.03%. The peak stress of the confined concrete decreased by 52.1% and its peak strain increased by 12.2 times, respectively. Moreover, the time-dependent seismic fragilities of the aging RC columns under different damage states exhibited a nonlinear increase as the service life increased.
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Cui, Fengkun, Guangzhu Guan, Long Cui, Mian Li, Shuwen Deng e Huihui Li. "Seismic Fragility Assessment of RC Columns Exposed to the Freeze-Thaw Damage". Buildings 13, n.º 1 (3 de janeiro de 2023): 126. http://dx.doi.org/10.3390/buildings13010126.
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Freeze–thaw damage is one of the primary causes deteriorating the seismic resistance of reinforced concrete (RC) structures. This paper proposed a freeze–thaw damage deterioration model for C30 concrete, and it can be employed to study the time-varying seismic performance of aging RC columns. Next, this study developed a seismic fragility analysis framework for deteriorating RC columns considering the effect of freeze–thaw damage. Considering the geometric parameters of the case-study bridge, the deterioration characteristics of material, and the uncertainties involved in structural modeling and ground motions, a probabilistic seismic fragility analysis on aging RC columns was conducted. The results indicate that the influence of freeze–thaw damage cannot be ignored in studying the seismic performance of aging RC structures. The seismic fragilities of deteriorating RC columns shown a nonlinear increase trend as the increased of freeze–thaw cycles and severity of the damage state. In the early stage of freeze–thaw cycles, the seismic fragilities of RC columns increased slowly. However, the closer to the later stage of freeze–thaw cycles, the more significant of the increase in the seismic fragilities of the columns.
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Malhotra, Praveen K., Paul E. Senseny, Antonio C. Braga e Roger L. Allard. "Testing Sprinkler-Pipe Seismic-Brace Components". Earthquake Spectra 19, n.º 1 (fevereiro de 2003): 87–109. http://dx.doi.org/10.1193/1.1543160.
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The design codes and standards (e.g., UBC, IBC, NFPA-13) estimate the amplitude of the seismic load in sprinkler-pipe braces, but they do not specify the number of cycles for which this load must be resisted by various components of pipe braces. Because the components can fail in low-cycle fatigue, the number of load cycles must be considered in establishing the strength of the brace components. The first part of this study deals with determining the number of cycles for which a component must resist its rated capacity. Strong-motion records from 18 strongly shaken buildings were incorporated into a low-cycle fatigue model to develop a test criterion for measuring the seismic strength of brace components. In the second part of this study, a series of tests were conducted to gain insight into the cyclic behavior of brace components. Finally, a test protocol was established to measure the seismic strength of brace components. With some modifications, the protocol can be applied to many other nonstructural components.
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Muratalieva, Zhazgul, e Aiymjan Omuralieva. "Monitoring the dynamics of seismicity within the Kemin-Chilik zone, generating M≥8 earthquakes". Russian Journal of Seismology 2, n.º 4 (16 de dezembro de 2020): 51–62. http://dx.doi.org/10.35540/2686-7907.2020.4.05.
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The dynamics of seismic processes at the junction of the Tien Shan mountain building area and the Kazakh shield is presented in the paper. It is noted that the Tien Shan’s lithosphere over thrusts the Kazakh Shield’s lithosphere, and the Kazakh Shield’s lithosphere under thrusts beneath the Tien Shan’s lithosphere based on the seismic tomographic and seismotectonic data. Low-velocity heterogeneity is distinguished at the junction of these lithospheres, under where a low-velocity anomaly flow is assumed in the mantle. Marginal (active structures of the Ili basin, Zaili mountain range), and middle (active structures of the Kemin, Chilik basins, Kungei mountain range) subzones with characteristic seismicity and seismic regimes are formed here. Seismogenic zones are distinguished (from north to south): Predzaili, Kemin-Chilik, Predkungei. Powerful earthquakes with M>8 occur in the Kemin-Chilik seismogenic zone (about 250 km long and up to 25 km wide), and earthquakes with M=7-8 - in the Predza-ili and Predkungei seismogenic zones. The dynamics of the earthquakes’ sequence is predetermined by the dynamics of the hierarchy of faults and blocks in the junction zone. The sequence of earthquakes is expressed by the hierarchy of seismic cycles. Seismic activation period, a peak of seismic activation, a period of seismic activation’s decay, and seismic calm period are distinguished in every cycle. Strong earthquakes take place in a first-order cycle with a long period, significant and small earthquakes - in cycles with corresponding short periods. The seismicity level of the study area is determined by the trajectory of the seismic cycles’ association. Dynamic segmentation and dynamic sectorization, vectors of seismic activity directed from the east and west to the highly compressed central part of the region are noted in the spatial and temporal distribution of earthquakes at the junction of the Tien Shan and the Kazakh shield.
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Viete, Daniel R., Bradley R. Hacker, Mark B. Allen, Gareth G. E. Seward, Mark J. Tobin, Chris S. Kelley, Gianfelice Cinque e Andrew R. Duckworth. "Metamorphic records of multiple seismic cycles during subduction". Science Advances 4, n.º 3 (março de 2018): eaaq0234. http://dx.doi.org/10.1126/sciadv.aaq0234.
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Wu, Jieqiong, Jian Zhang, Bo Diao, Shaohong Cheng e Yinghua Ye. "Hysteretic Behavior of Eccentrically Loaded Reinforced Air-Entrained Concrete Columns under Combined Effects of Freeze-Thaw Cycles and Seawater Corrosion". Advances in Civil Engineering 2018 (19 de julho de 2018): 1–10. http://dx.doi.org/10.1155/2018/3931791.
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Besides service loads, reinforced concrete structures in cold coastal seismic regions are subjected to multiple attacks of freeze-thaw cycles and seawater corrosion as well as the earthquake struck. An experimental study was conducted to investigate the seismic response of eccentrically loaded reinforced air-entrained concrete columns under alternative actions of freeze-thaw cycles and chloride corrosion. Results show that, after 300 times of freeze-thaw cycles alternated with 100 times of seawater immersion, the hysteretic behavior of the eccentrically loaded columns manifested an apparent asymmetric pattern. Under forward cyclic load, the existence of larger eccentric load rendered the reduction of the ultimate load and the ductility of a column by up to 20.3% and 46.05%, respectively, but it had a positive effect if reverse cyclic load was applied. The presence of eccentric load could have a considerable impact on the seismic behavior of reinforced air-entrained concrete columns served in an aggressive environment.
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Kwiatek, Grzegorz, T. H. W. Goebel e Georg Dresen. "Seismic moment tensor andbvalue variations over successive seismic cycles in laboratory stick-slip experiments". Geophysical Research Letters 41, n.º 16 (20 de agosto de 2014): 5838–46. http://dx.doi.org/10.1002/2014gl060159.
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Gandelli, Emanuele, Dario De Domenico e Virginio Quaglini. "Cyclic engagement of hysteretic steel dampers in braced buildings: a parametric investigation". Bulletin of Earthquake Engineering 19, n.º 12 (1 de julho de 2021): 5219–51. http://dx.doi.org/10.1007/s10518-021-01156-3.
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AbstractHysteretic steel dampers have been effectively used to improve the seismic performance of framed buildings by confining the dissipation of seismic energy into sacrifical, replaceable devices which are not part of the gravity framing system. The number of cycles sustained by the dampers during the earthquake is a primary design parameter, since it can be associated to low-cycle fatigue, with ensuing degradation of the mechanical properties and potential failure of the system. Current standards, like e.g. the European code EN 15129, indeed prescribe, for the initial qualification and the production control of hysteretic steel dampers, cyclic tests in which the devices are assessed over ten cycles with amplitude equal to the seismic design displacement dbd. This paper presents a parametric study focused on the number of effective cycles of the damper during a design earthquake in order to assess the reliability of the testing procedure proposed by the standards. The study considers typical applications of hysteretic steel dampers in low and medium-rise steel and reinforced concrete framed buildings and different ductility requirements. The results point out that the cyclic engagement of the damper is primarily affected by the fundamental period of the braced building and the design spectrum, and that, depending on these parameters, the actual number of cycles can be substantially smaller or larger that recommended by the standards. A more refined criterion for establishing the number of cycles to be implemented in testing protocols is eventually formulated.
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Wang, Fred P., Jiachun Dai e Charles Kerans. "Modeling dolomitized carbonate‐ramp reservoirs: A case study of the Seminole San Andres unit—Part II, Seismic modeling, reservoir geostatistics, and reservoir simulation". GEOPHYSICS 63, n.º 6 (novembro de 1998): 1876–84. http://dx.doi.org/10.1190/1.1444480.
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In part I of this paper, we discussed the rock‐fabric/petrophysical classes for dolomitized carbonate‐ramp rocks, the effects of rock fabric and pore type on petrophysical properties, petrophysical models for analyzing wireline logs, the critical scales for defining geologic framework, and 3-D geologic modeling. Part II focuses on geophysical and engineering characterizations, including seismic modeling, reservoir geostatistics, stochastic modeling, and reservoir simulation. Synthetic seismograms of 30 to 200 Hz were generated to study the level of seismic resolution required to capture the high‐frequency geologic features in dolomitized carbonate‐ramp reservoirs. At frequencies <70 Hz, neither the high‐frequency cycles nor the rock‐fabric units can be identified in seismic data because the tuning thickness of seismic data is much greater than the average thickness of high‐frequency cycles of 6 m. At frequencies >100 Hz, major high‐porosity and dense mudstone units can be better differentiated, while the rock‐fabric units within high‐frequency cycles can be captured at frequencies higher than 200 Hz. Seismic inversion was performed on the 30- to 200-Hz synthetic seismograms to investigate the level of seismic resolution required to recover the high‐resolution inverted impedance logs. When seismic data were noise free, wavelets were known and sampling rates were high; deconvolution techniques yielded perfect inversion results. When the seismic data were noisy, the inverted reflectivity profiles were poor and complicated by numerous high‐frequency spikes, which can be significantly removed using the moving averaging techniques. When wavelets were not known, the predictive deconvolution gave satisfactory inversion results. These results suggest that interwell information required for reservoir characterization can be recovered from low‐frequency seismic data by inversion. Outcrop data were collected to investigate effects of sampling interval and scale‐up of block size on geostatistical parameters. Semivariogram analysis of outcrop data showed that the sill of log permeability decreases and the correlation length increases with an increase of horizontal block size. Permeability models were generated using conventional linear interpolation, stochastic realizations without stratigraphic constraints, and stochastic realizations with stratigraphic constraints. The stratigraphic feature of upward‐shoaling sequences can be modeled in stochastic realizations constrained by the high‐frequency cycles and rock‐fabric flow units. Simulations of a fine‐scale Lawyer Canyon outcrop model were used to study the factors affecting waterflooding performance. Simulation results show that waterflooding performance depends strongly on the geometry and stacking pattern of the rock‐fabric units and on the location of production and injection wells.
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Zhang, Yixin, Shansuo Zheng, Xianliang Rong, Liguo Dong e Hao Zheng. "Seismic Performance of Reinforced Concrete Short Columns Subjected to Freeze–Thaw Cycles". Applied Sciences 9, n.º 13 (3 de julho de 2019): 2708. http://dx.doi.org/10.3390/app9132708.
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Previous research shows that freeze–thaw cycles represent one of the most dangerous threats to reinforced concrete (RC) structures. However, there is almost no experimental data on the effects of freeze–thaw cycles on the seismic behavior of RC columns showing flexure-shear failure. In this study, three columns with the shear span-to-depth ratio of 2.5 were subjected to different numbers of freeze–thaw cycles (FTCs) and pseudo-static testing. The seismic performance indexes of the specimens were analyzed in terms of hysteretic behavior, skeleton curves, shear deformation, and energy dissipation. The test observations show that the failure patterns of the test columns altered from the flexure dominated to shear dominated, owing to the more severe deterioration in shear capacity induced by freeze–thaw attack than in flexure capacity. The test results also indicate that freeze–thaw cycles significantly decrease the ductility and energy dissipation of test columns, and they increase the contributions of shear deformation to the total deformation.
Teses / dissertações sobre o assunto "Seismic cycles"
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Muldashev, Iskander [Verfasser], Michael [Akademischer Betreuer] Weber, Stephan Vladimir [Akademischer Betreuer] Sobolev e Volker [Akademischer Betreuer] John. "Modeling of the great earthquake seismic cycles / Iskander Muldashev ; Michael H. Weber, Stephan Vladimir Sobolev, Volker John". Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218402474/34.
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Muldashev, Iskander [Verfasser], Michael H. [Akademischer Betreuer] Weber, Stephan Vladimir [Akademischer Betreuer] Sobolev e Volker [Akademischer Betreuer] John. "Modeling of the great earthquake seismic cycles / Iskander Muldashev ; Michael H. Weber, Stephan Vladimir Sobolev, Volker John". Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218402474/34.
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Bagur, Laura. "Modeling fluid injection effects in dynamic fault rupture using Fast Boundary Element Methods". Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAE010.
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Les tremblements de terre d'origine naturelle ou anthropique provoquent d'importants dégâts humains et matériels. Dans les deux cas, la présence de fluides interstitiels influe sur le déclenchement des instabilités sismiques. Une nouvelle question d'actualité dans la communauté est de montrer que l'instabilité sismique peut être atténuée par un contrôle actif de la pression des fluides. Dans ce travail, nous étudions la capacité des méthodes d'éléments de frontière rapides (Fast BEMs) à fournir un solveur robuste multi-physique à grande échelle nécessaire à la modélisation des processus sismiques, de la sismicité induite et de leur atténuation.Dans une première partie, un solveur BEM rapide avec différents algorithmes d'intégration temporelle est utilisé. Nous évaluons les performances de diverses méthodes à pas de temps adaptatif sur la base de problèmes de cycles sismiques 2D usuels pour les failles planes.Nous proposons une solution asismique analytique pour effectuer des études de convergence et fournir une comparaison rigoureuse des capacités des différentes méthodes en plus des problèmes de cycles sismiques de référence testés.Nous montrons qu'une méthode hybride prédiction-correction / Runge-Kutta à pas de temps adaptatif permet non seulement une résolution précise mais aussi d'incorporer à la fois les effets inertiels et les couplages hydro-mécaniques dans les simulations de rupture dynamique de faille.Dans une deuxième partie, une fois les outils numériques développés pour des configurations standards, notre objectif est de prendre en compte les effets de l'injection de fluide sur le glissement sismique. Nous choisissons le cadre poroélastodynamique pour incorporer les effets de l'injection sur l'instabilité sismique. Un modèle poroélastodynamique complet nécessiterait des coûts de calcul ou des approximations non négligeables. Nous justifions rigoureusement quels effets fluides prédominants sont en jeu lors d'un tremblement de Terre ou d'un cycle sismique. Pour cela, nous effectuons une analyse dimensionnelle des équations, et illustrons les résultats en utilisant un problème de poroelastodynamique 1D simplifié. Plus précisément, nous montrons qu'à l'échelle de temps de l'instabilité sismique, les effets inertiels sont prédominants alors qu'une combinaison de la diffusion du fluide et de la déformation élastique de la matrice solide due à la variation de la pression interstitielle devrait être privilégiée à l'échelle de temps du cycle sismique, au lieu du modèle de diffusion principalement utilisé dans la littératureEarthquakes due to either natural or anthropogenic sources cause important human and material damage. In both cases, the presence of pore fluids influences the triggering of seismic instabilities.A new and timely question in the community is to show that the earthquake instability could be mitigated by active control of the fluid pressure. In this work, we study the ability of Fast Boundary Element Methods (Fast BEMs) to provide a multi-physic large-scale robust solver required for modeling earthquake processes, human induced seismicity and their mitigation.In a first part, a Fast BEM solver with different temporal integration algorithms is used. We assess the performances of various possible adaptive time-step methods on the basis of 2D seismic cycle benchmarks available for planar faults. We design an analytical aseismic solution to perform convergence studies and provide a rigorous comparison of the capacities of the different solving methods in addition to the seismic cycles benchmarks tested. We show that a hybrid prediction-correction / adaptive time-step Runge-Kutta method allows not only for an accurate solving but also to incorporate both inertial effects and hydro-mechanical couplings in dynamic fault rupture simulations.In a second part, once the numerical tools are developed for standard fault configurations, our objective is to take into account fluid injection effects on the seismic slip. We choose the poroelastodynamic framework to incorporate injection effects on the earthquake instability. A complete poroelastodynamic model would require non-negligible computational costs or approximations. We justify rigorously which predominant fluid effects are at stake during an earthquake or a seismic cycle. To this aim, we perform a dimensional analysis of the equations, and illustrate the results using a simplified 1D poroelastodynamic problem. We formally show that at the timescale of the earthquake instability, inertial effects are predominant whereas a combination of diffusion and elastic deformation due to pore pressure change should be privileged at the timescale of the seismic cycle, instead of the diffusion model mainly used in the literature
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Aben, Frans. "Experimental simulation of the seismic cycle in fault damage zones". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU012/document.
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Les séismes le long de grandes failles crustales représentent un danger énorme pour de nombreuses populations. Le mécanique de ces failles est influencé par des zones endommagées qui entourent le coeur de faille. La fracturation dans ces zones contrôle chaque étape du cycle sismique. En effet, cette zone contrôle la mécanique de la rupture sismique, elle est un conduit pour les fluides, réagit chimiquement sous l'effet de fluides réactifs, et facilite la déformation pendant les périodes post- et inter-sismiques. Dans cette thèse de doctorat, des expériences de laboratoire ont été réalisées pour mieux comprendre 1) la façon dont l'endommagement est généré pendant le chargement transitoire co-sismique, 2) comment l'endommagement permet de mieux contraindre le chargement co-sismique le long de grandes failles, et iii) comment les fractures peuvent se cicatriser au fil du temps et contrôler l'évolution de la perméabilité et de la résistance mécanique de la faille.L'introduction de la thèse propose une revue critique de la littérature sur la génération de dommages co-sismiques et en particulier sur la formation des roches pulvérisées. Le potentiel de ces roches comme marqueur des déformations co-sismiques est discuté. Bien que ces roches pulvérisées soient prometteuses pour ces aspects, plusieurs questions restent ouvertes.L'une de ces questions concerne les conditions de chargement transitoire nécessaires pour atteindre la pulvérisation. Le seuil de taux de deformation pour atteindre la pulvérisation peut être réduit par des endommagemments progressifs, au cours de ruptures sismiques successives. Des barres de Hopkinson ont été utilisées pour effectuer des chargements dynamique successifs d'une roche cristalline (monzonite). Les résultats montrent que le seuil pour atteindre la pulvérisation est réduit d'au moins 50% lorsque des chargements successives sont imposés. Cette thèse discute aussi pourquoi les roches pulvérisées sont presque toujours observées dans des roches cristallines et peu dans des roches sédimentaires poreuses. Pour comprendre cette observation, des expériences à haute vitesse de déformation ont été effectuées sur des grès de Rothbach. Les résultats montrent que la pulvérisation des grains eux mêmes ne se produit pas dans les grès. L'endommagement reste se produit principalement à une échelle supérieure à celle grains, et des bandes de compaction sont observées. La compétition entre l'endommagement inter- et intra-granulaire est expliquée par les paramètres microstructuraux en combinant deux modèles micromécaniques classiques. Les microstructures observées dans les grès peuvent se former dans le régime quasi-statiques et aussi dans le régime dynamique. Par conséquent, il est recommandée d'être prudent lors de l'interprétation du mécanisme de deformation dans les roches sédimentaires proches de la surface. La dernière question abordée durant la thèse est la cicatrisation post-sismique de fractures co-sismiques. Des expériences ont été réalisées pour cicatriser des fissures par précipitation de calcite. Le but est l'étude du couplage entre l'augmentation de résistance mécanique de la roche fissurée et l'évolution de la perméabilité. Les échantillons fracturées ont été soumis à des conditions de pression et températures similaires de la croûte supérieure et à une percolation d'un fluide sursaturé en calcite pendant plusieurs mois. Ce couplage non-existe dans les premières étapes de la cicatrisation. Il est révélé par l'imagerie par tomographie aux rayons X que le scellement naissant des fractures se produit dans les porosités situées en aval de barrières d'écoulement, et donc dans des régions qui ne touchent pas les principales voies d'écoulement du fluide. Le découplage entre l'augmentation de résistance de la roche et la perméabilité suggère que les zones d'endommagement peu profondes dans les failles actives peuvent rester des conduits actifs pour les fluides plusieurs années après un séismeEarthquakes along large crustal scale faults are a huge hazard threatening large populations. The behavior of such faults is influenced by the fault damage zone that surrounds the fault core. Fracture damage in such fault damage zones influences each stage of the seismic cycle. The damage zone influences rupture mechanics, behaves as a fluid conduit to release pressurized fluids at depth or to give access to reactive fluids to alter the fault core, and facilitates strain during post- and interseismic periods. Also, it acts as an energy sink for earthquake energy. Here, laboratory experiments were performed to come to a better understanding of how this fracture damage is formed during coseismic transient loading, what this fracture damage can tell us about the earthquake rupture conditions along large faults, and how fracture damage is annihilated over time.First, coseismic damage generation, and specifically the formation of pulverized fault damage zone rock, is reviewed. The potential of these pulverized rocks as a coseismic marker for rupture mechanisms is discussed. Although these rocks are promising in that aspect, several open questions remain.One of these open questions is if the transient loading conditions needed for pulverization can be reduced by progressively damaging during many seismic events. The successive high strain rate loadings performed on quartz monzonites using a split Hopkinson pressure bar reveal that indeed the pulverization strain rate threshold is reduced by at least 50%.Another open question is why pulverized rocks are almost always observed in crystalline lithologies and not in more porous rock, even when crystalline and porous rocks are juxtaposed by a fault. To study this observation, high strain rate experiments were performed on porous Rothbach sandstone. The results show that pervasive pulverization below the grain scale, such as observed in crystalline rock, does not occur in the sandstone samples for the explored strain rate range (60-150 s-1). Damage is mainly occurs at a scale superior to that of the scale of the grains, with intragranular deformation occurring only in weaker regions where compaction bands are formed. The competition between inter- and intragranular damage during dynamic loading is explained with the geometric parameters of the rock in combination with two classic micromechanical models: the Hertzian contact model and the pore-emanated crack model. In conclusion, the observed microstructures can form in both quasi-static and dynamic loading regimes. Therefore caution is advised when interpreting the mechanism responsible for near-fault damage in sedimentary rock near the surface. Moreover, the results suggest that different responses of different lithologies to transient loading are responsible for sub-surface damage zone asymmetry.Finally, post-seismic annihilation of coseismic damage by calcite assisted fracture sealing has been studied in experiments, so that the coupling between strengthening and permeability of the fracture network could be studied. A sample-scale fracture network was introduced in quartz monzonite samples, followed exposure to upper crustal conditions and percolation of a fluid saturated with calcite for several months. A large recovery of up to 50% of the initial P-wave velocity drop has been observed after the sealing experiment. In contrast, the permeability remained more or less constant for the duration of the experiment. This lack of coupling between strengthening and permeability in the first stages of sealing is explained by X-ray computed micro tomography. Incipient sealing in the fracture spaces occurs downstream of flow barriers, thus in regions that do not affect the main fluid flow pathways. The decoupling of strength recovery and permeability suggests that shallow fault damage zones can remain fluid conduits for years after a seismic event, leading to significant transformations of the core and the damage zone of faults with time
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Cossette, Élise. "Crustal Seismic Anisotropy and Structure from Textural and Seismic Investigations in the Cycladic Region, Greece". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32475.
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In the first article, the seismic properties for a suite of rocks along the West Cycladic Detachment System (Greece) are calculated, using Electron backscatter diffraction (EBSD) measurements and the minerals’ elastic stiffness tensors. Muscovite and glaucophane well defined crystallographic preferred orientation increases the seismic anisotropy. Maximum Pwave velocities have the same orientation as the Miocene extension and maximum S-wave anisotropy is subhorizontal, parallel with mineral alignment, suggesting strong radial anisotropy with a slow subvertical axis of symmetry. In the second article, teleseismic receiver functions are calculated for an array of stations in the Cyclades and decomposed into back-azimuth harmonics to visualise the variations in structure and anisotropy across the array. Synthetic receiver functions are modeled using the first order structural observations of seismic discontinuities and EBSD data. They indicate 5% of anisotropy with slow symmetry axis in the upper crust, and demonstrate the importance of rock textural constraints in seismic velocity profile interpretation.
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Al-Shaikh, Abdulrahman Hassan. "Cyclic static and seismic loading of laterally confined concrete prisms". Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38219.
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Fiorin, Laura. "Seismic assessment of suspended ceilings through cyclic quasi-static tests". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3423162.
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The purpose of this work is the evaluation of the seismic behaviour of suspended ceilings by means of a combined experimental and numerical approach.
As concerning the experimental aspects, nowadays the most common experimental produre applied to suspended ceilings worldwide regards shake-table tests, with a protocol defined to certify the ceilings for a determined seismic level. This methodology has some shortcomings, including the high cost and the influence of the input chosen on the experimental results. In fact, these tests have the aim to certify the product rather than providing mechanical characteristics of the specimen tested. Moreover, the results obtained with the certification process cannot be extended to similar products or geographic zones with different seismic risk. To overcome these limitations, an innovative experimental setup for monotonic and cyclic testing of suspended ceiling systems was designed, realized and applied.
In order to have a complete characterization of suspended ceilings, an initial experimental campaign on inner joints was realized. These components, in fact, performed poorly in past earthquakes. In detail, 'standard' joints were compared to 'seismic' joints, specifically designed to resist to earthquake motion.
Real-scale tests were then performed on the most common T-Grid suspended ceilings and other two typologies of metal ceilings with different structure. Moreover, dry-wall suspended ceilings with single and double plasterboard were tested. For each typology one monotonic and one cyclic quasi-static test were performed. Monotonic tests have the aim to identify the yielding parameters and the damage mechanisms and cyclic tests are performed according to the protocol described in FEMA 461 for cyclic quasi-static tests of non-structural components. The results allow to define the performance of suspended ceilings and to elaborate their capacity curves.
As concerning the numerical part of the work, a numerical cascading approach was applied to study the uncoupled behaviour of suspended ceilings installed at different levels of buildings. Results from experimental campaign were used as input data for the numerical anlyses. Elastic linear time history analyses were performed on multi-story buildings with different vibration periods and the elastic floor response spectra were defined. Capacity curves defined experimentally and floor spectra were plotted in an ADRS (Acceleration Displacement Response Spectrum) domain in order to assess the seismic demand in terms of acceleration and displacement of suspended ceilings compared to their capacities. Dynamic analyses of suspended ceilings were conduced both in linear and non linear hypothesis and the results compared in order to assess the effectiveness of standard linear, or equivalent linear, static calculations.Lo scopo della tesi è la valutazione del comportamento sismico di controsoffitti, tramite prove cicliche quasi statiche. La tipologia di prove più comune ad oggi, infatti, riguarda prove su tavole vibrante con un protocollo definito per certificare il prodotto per una certa azione sismica. Queste prove presentano varie limitazioni, tra cui il costo elevato e la stretta correlazione tra risultato e input scelto. Le prove infatti non hanno specifico scopo di ricerca se non l’obiettivo di certificare un prodotto, non forniscono informazioni sulle prestazioni meccaniche dei componenti testati e non permettono di estendere i risultati ottenuti ne su prodotti simili ne in zone geografiche con diverso rischio sismico. È stato quindi progettato un setup di prova innovativo in grado di realizzare prove monotone e cicliche quasi statiche su controsoffitti. Questa tipologia di prove permette di superare le limitazioni dell’attuale procedura sperimentale. Al fine di ottenere una caratterizzazione completa dei controsoffitti, sono stati testati i giunti interni, questi componenti infatti sono risultati danneggiati in seguito a eventi sismici. In particolare, sono stati testati sia giunti ‘standard’ che giunti ‘antisismici’, facenti parte di una particolare linea progettata per resistere all’azione sismica. Sono stati testati a grandezza reale sia controsoffitti con struttura a T (che rappresentano la tipologia più diffusa globalmente), che altri due controsoffitti con diversa sottostruttura metallica, infine le prove hanno riguardato anche controsoffitti con pannelli continui in cartongesso. Per ogni tipologia sono stati eseguite una prova monotona, al fine di individuare i parametri di snervamento e il meccanismo di rottura, e una prova ciclica, seguendo il protocollo indicato nelle FEMA 461 per prove cicliche quasi statiche per componenti non strutturali. I risultati ottenuti hanno permesso di definire la prestazione degli elementi testati e di elaborarne la curva di capacità. Tramite approccio numerico “a cascata”, che permette di eseguire uno studio disaccoppiato dei due elementi, è stato possibile studiare il comportamento dei controsoffitti installati a diversi piani. Sono state realizzate analisi time-history lineari elastiche su edifici multi-piano con diverso periodo di vibrazione e sono stati ricavati gli spettri di risposta al piano. Le curve di capacità dei controsoffitti, definite sperimentalmente, e gli spettri al piano sono stati definiti in un dominio ADRS (Acceleration Displacement Response Domain) al fine di valutare la domanda sismica in termini di spostamento e accellerazione in funzione della capacità dei controsoffitti.
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Lachaud, Cédric. "Etude du cycle sismique sur une expérience analogique de zone de faille : caractérisation de la déformation par suivi micro-sismique". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU002/document.
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Le cycle sismique résulte de la compétition entre des mécanismes de renforcement et d'endommagement. Le temps de récurrence entre les grands séismes fait qu'il est difficile d'observer des cycles complets. L'étude expérimentale des mécanismes de déformation et de nucléation des fractures a permis de mieux contraindre les processus à l'origine des séismes. Le rôle de la cicatrisation sur l'évolution de la résistance d'une faille soumise à une déformation stationnaire à été étudié expérimentalement par Weiss et al (2016). Dans cette expérience, une faille est créée dans une plaque de glace par cisaillement. Les mécanismes de cicatrisation sont obtenus par le regel de l'eau présente dans la zone de déformation. Dans le cadre de cette thèse, ce dispositif expérimental a été étendu pour permettre le suivi micro-sismique de la déformation imposée. Les mécanismes de déformation fragile émettent des ondes élastiques détectables qui se propagent dans le milieu, nous permettant de les caractériser. En raison de la géométrie en plaque du milieu, on observe la propagation d'ondes guidées similaire aux modes de Lamb symétrique et antisymétrique.Les fractures de grandes tailles se distribuent selon une loi de puissance en $10^{-bm}$ similaire à ce qui est observé en sismologie. Cependant, lors des expériences de déformation stationnaires, la valeur de $b$ est large ($b=3$), et bien supérieure à ce qui est observée dans la croûte terrestre ($b=1$). Une valeur de $b$ aussi élevée traduit le fait que la déformation est principalement accommodée de façon asismique ou part des fractures trop petites pour être détectées par notre méthode. Lorsque le rôle de la cicatrisation est renforcée par rapport à l'endommagement, on observe une diminution de la valeur de $b$. Ce changement de distribution est probablement dû à la diminution des hétérogénéités de structure dans la faille et à une augmentation de sa capacité à accumuler une contrainte plus élevée avant la rupture, permettant aux fractures de se propager sur de plus longues distances. Une partie importante de la sismicité correspond à des multiplets qui semblent être des produits passifs de la déformation. Ce comportement est similaire à ce qui est observé pour les essaims de séismes déclenchés par des transitoires de déformation : valeur de $b$ grande, absence de choc principal et peu de déclenchement de répliques. Pour des taux de déformation faibles, on observe une augmentation des chutes de couple avec la magnitude de la forme $Delta Gamma sim M_0 sim 10^{1.2m}$, similaire à ce qui est observé dans la croûte terrestre, $M_0 sim 10^{1.5m}$. Il est donc possible que la relation observée en sismologie s'étende aux petites magnitudes observées ici. Une diminution du couplage sismique est observé avec l'augmentation du taux de glissement $Omega$. Pour finir, pour une fracture de magnitude donnée, on observe une diminution de la chute de couple avec l'augmentation de $Omega$. Ce comportement peut être expliqué par la diminution du couplage sismique et/ou une dépendance du taux de cicatrisationThe deformation observed along a seismic fault can be described as the succession of phases for which the fault accumulate stress imposed by the steady deformation of the surrounding regions, and phases of sudden sliding during which the stress is relaxed: the earthquakes. After the rupture, strengthening mechanisms are required to make possible the new accumulation of elastic stress. Therefore, the seismic cycle results in the steady competition between strengthening and damage. The aim of this study is to explore the role of cohesion-healing on the fault deformation dynamic, as well as to characterize the effect of slip rate on the seismicity. The experimental set-up designed by Weiss et al (2016) has been extended in this study to carry out a micro-seismic monitoring of the deformation. This experiment consists in the shear deformation of a fault created in a thin ice plate overlying a water column. Cohesion-healing mechanisms are achieved through freezing of the water along the fault. The damage mechanisms and the spatial and temporal distribution of the deformation can be characterized thanks to the detectable elastic waves emitted by the fracturing. Because of the plate geometry and underlying water column, we observed guided waves similar to the Lambs symmetric and antisymmetric modes.The largest fractures distribute according to a power law of the form $10^{-bm}$ that is similar to the one observed in seismology. At a constant sliding rate, we observe a large $b$ value, $simeq 3$, which is much larger than the value observed in the Earth's crust ($b=1$). This large $b$ value indicates that the deformation is mainly accommodated aseismically or by small, undetected, fractures. During Slide-Hold-Slide experiment that corresponds to a case for which the cohesion-healing is enhanced compared to the damage, we observe a decrease in the $b$-value likely due to a decrease in fault heterogeneity and an increase of the fault ability to store more elastic stress before the rupture, allowing the fractures to grow larger. An important part of the fractures are multiplets, swarms of fractures, which seem to be passive by-products of the imposed deformation. This behaviour is similar to the one observed for swarm seismicity triggered by slip transient: high $b$-value, no identified mainshock, and very little triggering. For small driving rate $Omega$, we observe an increase in torque drop amplitude with magnitude, $Delta Gamma sim M_0 sim 10^{1.2m}$, similar to the relation observed in seismology, $M_0 sim 10^{1.5m}$. Thus, the latter could be extended to small magnitudes observed in this study. A decrease of the seismic coupling is observed through the decrease in the number of fractures per unit of slip, and because in average a fracture behaves similarly at the different $Omega$ tested. Finally, for a given magnitude interval, we observe a decrease in torque drop amplitude with the increase in $Omega$. This could be explained by the observed decrease in seismic coupling or by a decrease in strengthening rate with $Omega$ that is not observed
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Shin, Hyun. "Life-Cycle Cost-Based Optimal Seismic Design of Structures with Energy Dissipation Devices". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/40399.
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Seismic designs of building structures are currently made based on the design criterion
of life-safety and this requires that the structures do not collapse to compromise safety
of people in the structure, but they can be designed to experience some damage.
However, this design approach has allowed large economic losses primarily due to the
damage to the nonstructural components at relatively moderate levels of seismic
intensities. This led to a new thinking about design approach called performance-based
design approach that satisfies the life-safety objective at the same time, reduces the
economic loss to an acceptable level. The performance-based design approaches are
multi-level design that addresses several different levels of structural performances
under different levels of seismic intensities. In this study, we have investigated the use
of energy dissipating damping devices to achieve the performance of a building
structure in a desirable manner over all levels of seismic intensity. Since the initial
motivation of performance-based design was reducing economic loss, the life-cycle
cost-based optimization is considered in this study to obtain the optimal designs with
different damping devices. For the optimal design, three types of devices are used in this
study: fluid viscous dampers, solid visco-elastic dampers, and yielding metallic
dampers. The combinations of two different types of dampers are also examined in this
study. The genetic algorithm (GA) approach is adopted as an optimizer that searches for
the optimal solution in an iterative manner. Numerical results from the application of
the optimal design to the selected model building are presented to demonstrate the
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applicability of the developed approach and to estimate the effectiveness of the obtained
optimal design with each device. It is shown in the results that the optimal design with
each individual damping devices or the combination of two different types of damping
devices are very effective in reducing the expected failure cost as well as the
displacement response quantities and fragilities. The results also show that the optimal
designs focus relatively more on reducing economic losses for the lower but more
frequent excitation intensities as these intensities contribute most to the failure costs.Ph. D.
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Schmidt, Johannes. "Deep seismic studies in the Western part of the Baltic shield /". Uppsala : Uppsala university of Uppsala, 2000. http://catalogue.bnf.fr/ark:/12148/cb40232940n.
Texto completo da fonteLivros sobre o assunto "Seismic cycles"
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Dal Zilio, Luca. Cross-Scale Modeling of Mountain Building and the Seismic Cycle: From Alps to Himalaya. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-28991-1.
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Oda, Juntarō. Seishin iryō ni hōmurareta hitobito: Sennyū rupo shakaiteki nyūin. Tōkyō: Kōbunsha, 2011.
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Rolandone, Frederique. Seismic Cycle: From Observation to Modeling. Wiley & Sons, Incorporated, John, 2022.
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Rolandone, Frederique. Seismic Cycle: From Observation to Modeling. Wiley & Sons, Incorporated, John, 2022.
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Rolandone, Frederique. Seismic Cycle: From Observation to Modeling. Wiley & Sons, Incorporated, John, 2022.
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Seismic Cycle: From Observation to Modeling. Wiley & Sons, Incorporated, John, 2022.
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Marfurt, Kurt J. Seismic Attributes As the Framework for Data Integration Throughout the Oilfield Life Cycle. Society of Exploration Geophysicists, 2018.
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Zilio, Luca Dal. Cross-Scale Modeling of Mountain Building and the Seismic Cycle: From Alps to Himalaya. Springer, 2019.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Seismic cycles"
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Zhang, Fan, Kun Zhang, Zheng Liu e Yi Xie. "Mechanical properties and fracture failure law of single fracture marble under cyclic loading after freeze-thaw cycles". In Building Seismic Monitoring and Detection Technology, 116–21. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003409564-15.
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Li, Jian, Yuzai Zhou, Jian Hong, Guangbo Wang, Shiyao Liu e Chengxiang Xu. "Tensile damage mechanism of chemical anchor bolt groups in buildings after freeze-thaw cycles". In Building Seismic Monitoring and Detection Technology, 472–81. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003409564-59.
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Sammis, Charles G., e Stewart W. Smith. "Seismic Cycles and the Evolution of Stress Correlation in Cellular Automaton Models of Finite Fault Networks". In Seismicity Patterns, their Statistical Significance and Physical Meaning, 307–34. Basel: Birkhäuser Basel, 1999. http://dx.doi.org/10.1007/978-3-0348-8677-2_6.
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Ma, Xiaofei, Yinquan Yu e Zhe Wang. "Structural Seismic Performance of Prefabricated Steel Plate Shear Wall with High Energy Dissipation". In Advances in Frontier Research on Engineering Structures, 475–86. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8657-4_43.
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AbstractChina is located at the intersection of the Pacific Rim seismic belt and the Alpine Mountain-Himalayan seismic belt. Earthquakes occur frequently and with high intensity in China, and the structural damage caused by earthquakes leads to huge casualties and serious economic losses. Steel plate shear wall exhibits satisfying seismic performance which is the key to its application in high-rise buildings and high intensity areas. Meanwhile, the industrialization of new construction requires prefabricated steel plate shear wall structure. In this paper, a kind of prefabricated steel plate shear wall with high energy dissipation is proposed. The finite element study on the seismic performance of the prefabricated steel plate shear wall under low cyclic load was carried out by varying the width-to-thickness ratio of steel connecting plate belt and width-to-thickness ratio of ring damper. The failure modes, hysteresis curves, skeleton curves, stiffness degradation, energy dissipation and displacement ductility coefficients were analyzed. The results showed that the hysteretic curves of the prefabricated steel plate shear wall are relatively full under low cyclic load, and the displacement ductility coefficients are above 8. It is noted that the seismic performance of the prefabricated steel plate shear wall is advantageous. It is suggested that width-to-thickness ratio of the steel connecting plate belt and the width-to-thickness ratio of the ring damper are 3.75 for engineering practice.
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Evensen, Geir, Femke C. Vossepoel e Peter Jan van Leeuwen. "Particle Filter for Seismic-Cycle Estimation". In Springer Textbooks in Earth Sciences, Geography and Environment, 187–98. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-96709-3_19.
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AbstractThe particle filter is an effective data-assimilation method for low-dimensional, nonlinear systems. It is easy to implement, and it is straightforward to include model error, parameters, and controls in the state vector. This chapter demonstrates the use of a particle filter in the case of a parameter bias.
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Salonikios, T., I. Tegos, A. Kappos e G. Penelis. "Cyclic shear behaviour of low slenderness RC walls". In European Seismic Design Practice, 293–99. London: Routledge, 2022. http://dx.doi.org/10.1201/9780203756492-45.
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Karayannis, C. G., K. K. Sideris e C. M. Economou. "Response of repaired RC exterior joints under cyclic loading". In European Seismic Design Practice, 285–92. London: Routledge, 2022. http://dx.doi.org/10.1201/9780203756492-44.
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Aiello, Maria Antonietta, e Luciano Ombres. "Ductility values of steel members in presence of cyclic actions". In European Seismic Design Practice, 605–10. London: Routledge, 2022. http://dx.doi.org/10.1201/9780203756492-91.
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Matsuzaki, H. "Seismic damage control of bridges with deteriorated seismic isolation bearings by rupture of anchor bolts". In Life-Cycle of Structures and Infrastructure Systems, 906–13. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003323020-110.
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Lawrence, Jesse F., e Michael E. Wysession. "Seismic Evidence for Subduction-Transported Water in the Lower Mantle". In Earth's Deep Water Cycle, 251–61. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/168gm19.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Seismic cycles"
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Lowrie, A., e K. S. Hoffman. "Neogene Third And Fourth-Order Seismic Cycles In Louisiana Offshore". In Offshore Technology Conference. Offshore Technology Conference, 1988. http://dx.doi.org/10.4043/5716-ms.
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Zhao, Wangwen, Richard Turner e Jian Liang. "Strain Based Failure Assessment for Offshore Structures Under Seismic Loading". In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57008.
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Under seismic loading, structural hot spots can experience very high levels of stress and many random stress reversals. Conventional stress based methods cannot assess the failure state in detail when stress is beyond the elastic limit and nominal stress reversals are more than double the yield stress. A method has been created to fully reproduce the true stress/ strain history by using 1) generalised Masing’s rule with equivalent cyclic energy dissipation to model cyclic stress/strain relation, 2) Neuber’s method to calculate inelastic strain concentration factor, and 3) relative effective notch factor determined from comparing S-N curves of different joint classes. From this reproduced strain history, strain cycles can be counted and low cycle fatigue analysis can be conducted by using Miner’s rule and by estimating damage from the strain based failure criteria such as Coffin-Mason method. This method has been implemented in a numeric procedure and coded in a FORTRAN program called CYSTRA (as for CYclic STRain Analysis). It takes input of “nominal” random stress history directly from general structural software, linear or non-linear, local or global, and calculates extreme strain and strain cycles at multiple hot spots for the whole structure efficiently. Thus it greatly facilitates failure assessment for offshore structures which can have a large number of hot spots within the structure, unlike mechanical devices commonly assessed in strain based analysis where detailed FE based methods can be used.
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Kumar, Rajive, T. Al-Mutairi, P. Bansal, Khushboo Havelia, Faical Ben Amor, Bassam Farhan, Aya Ibrahim et al. "Connecting the Dots between Geology and Seismic to Mitigate Drilling Risks: Mapping & Characterization of the High Pressure High Temperature Gotnia Formation in Kuwait". In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207452-ms.
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Abstract As Kuwait focuses on developing the deep Jurassic reservoirs, the Gotnia Formation presents significant drilling challenges. It is the regional seal, consisting of alternating Salt and Anhydrite cycles, with over-pressured carbonate streaks, which are also targets for future exploration. The objective of this study was to unravel the Gotnia architecture, through detailed mapping of the intermediate cycles, mitigating drilling risks and characterizing the carbonate reservoirs. A combination of noise attenuation, bandwidth extension and seismic adaptive wavelet processing (SAWP)) was applied on the seismic data, to improve the signal-to-noise ratio of the seismic data between 50Hz to 70Hz and therefore reveal the Anhydrite cycles, which house the carbonate streaks. The Salt-Anhydrite cycles were correlated, using Triple Combo and Elastic logs, in seventy-six wells, and spatially interpreted on the band-limited P-impedance volume, generated through pre-stack inversion. Pinched out cycles were identified by integrating mud logs with seismic data and depositional trends. Pre-stack stochastic inversion was performed to map the thin carbonate streaks and characterize the carbonate reservoirs. The improved seismic resolution resulted in superior results compared to the legacy cube and aided in enhancing the reflector continuity of Salt-Anhydrite cycles. In corroboration with the well data, three cycles of alternating salt and anhydrite, with varying thickness, were mapped. These cycles showed a distinctive impedance contrast and were noticeably more visible on the P-impedance volume, compared to the seismic amplitude volume. The second Anhydrite cycle was missing in some wells and the lateral extension of the pinch-outs was interpreted and validated based on the P-impedance volume. As the carbonate streaks were beyond the seismic resolution, they were not visible on the Deterministic P-impedance. The amount of thin carbonate streaks within the Anhydrite cycles could be qualitatively assessed based on the impedance values of the entire zone. Areas, within the zone, with a higher number of and more porous carbonate streaks displayed lowering of the overall impedance values in the Anhydrite zones, and could pose drilling risks. This information was used to guide the pre-stack stochastic inversion to populate the thin carbonate streaks and generate a high-resolution facies volume, through Bayesian Classification. Through this study, the expected cycles and over-pressured carbonate layers in the Gotnia formation were predicted, which can be used to plan and manage the drilling risks and reduce operational costs. This study presents an integrated and iterative approach to interpretation, where the well log analysis, seismic inversion and horizon interpretation were done in parallel, to develop a better understanding of the sub-surface. This workflow will be especially useful for interpretation of over-pressured overburden zones or cap rocks, where the available log data can be limited.
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Zhou, Runze, Ikuo Kojima, Takuyo Kaida e Hirokazu Tsuji. "FEM Analysis on Pressure Vessel Components Containing LTAs Against Seismic Load Using Combined Non-Linear Isotropic/Kinematic Hardening Model". In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97129.
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Fitness-for-service (FFS) assessments are quantitative engineering evaluations that perform to demonstrate the integrity of an in-service component that may contain a flaw or damage [1]. It can be used to make run-repair-replace decisions to help determine if pressured equipment containing flaw that have been identified by inspection can continue to operate safety for some period of time. This paper provides a FFS assessment on carbon steel pipe which contained a LTA (Local Thin Area) against seismic load by FEM (Finite Element Method) analysis. ABAQUS Ver. 6.10, which has the combined isotropic / kinematic hardening model [2], is used to simulate the LTA contained carbon steel pipe against seismic load. Material parameters in the hardening model are identified by a symmetric strain cycle experiment based on ASTM E606. Isotropic hardening component is introduced by specifying the equivalent stress defining the size of the yield surface, as a tabular function of the equivalent plastic strain. Kinematic hardening component is obtained from the stabilized cycle of a specimen that is subjected to symmetric stain cycles. The authors introduced the way how to calibrate the material parameters of combined isotropic / kinematic hardening model. Then the authors calculated up to 100 cycles on carbon steel pipe which contained a Local Thin Area against seismic load at 300 degrees centigrade. The results comparison between FEM analysis and experiment shows that stress-strain hysteresis loop tendency and number of cycles to failure are predicted accurately.
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Mitsuya, Masaki, e Hiroshi Yatabe. "Cyclic Deformation and Buckling Behavior of Pipe With Local Metal Loss Subjected to Seismic Ground Motion". In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57723.
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Buried pipelines may be deformed due to earthquakes and also corrode despite corrosion control measures such as protective coatings and cathodic protection. In such cases, it is necessary to ensure the integrity of the corroded pipelines against earthquakes. This study developed a method to evaluate the earthquake resistance of corroded pipelines subjected to seismic ground motions. Axial cyclic loading experiments were carried out on line pipes subjected to seismic motion to clarify the cyclic deformation behavior until buckling occurs. The test pipes were machined so that each one would have a different degree of local metal loss. As the cyclic loading progressed, displacement shifted to the compression side due to the formation of a bulge. The pipe buckled after several cycles. To evaluate the earthquake resistance of different pipelines, with varying degrees of local metal loss, a finite-element analysis method was developed that simulates the cyclic deformation behavior. A combination of kinematic and isotropic hardening components was used to model the material properties. These components were obtained from small specimen tests that consisted of a monotonic tensile test and a low cycle fatigue test under a specific strain amplitude. This method enabled the successful prediction of the cyclic deformation behavior, including the number of cycles required for the buckling of pipes with varying degrees of metal loss. In addition, the effect of each dimension (depth, longitudinal length and circumferential width) of local metal loss on the cyclic buckling was studied. Furthermore, the kinematic hardening component was investigated for the different materials by the low cycle fatigue tests. The kinematic hardening components could be regarded as the same for all the materials when using this component as the material property for the finite-element analyses simulating the cyclic deformation behavior. This indicates that the cyclic deformation behavior of various line pipes can be evaluated only based on their respective tensile properties and common kinematic hardening component.
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Kim, Dongoh, Seunghak Yoo e Salvatore Di Simone. "Habshan Seismic Stratigraphy Framework to Reveal Stratigraphic Play Potential in Southeast Abu Dhabi, UAE". In ADIPEC. SPE, 2024. http://dx.doi.org/10.2118/222735-ms.
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Abstract The Lower Cretaceous (Berriasian to Valanginian) of Southeast Abu Dhabi, U.A.E. consists of a large carbonate platform system and the Habshan Formation is a major carbonate reservoir in the region, hosting significant hydrocarbon potential with more than 1,000 feet in reservoir thickness. The progressive nature and clinoform structures have been highlighted through many vintages of seismic imaging and previous stratigraphic studies. This underlines the necessity of understanding sequence stratigraphy to appreciate the variations and distribution of facies by the integration of all available geological and geophysical data in the study area. Seismic data interpretation based on a high-resolution 3D survey covering more than 4,400 sq-km was conducted to identify geological features and variations in the Habshan Formation. Data-driven interpretation utilizing different types of 3D seismic attribute volumes, including acoustic impedance volume, was used to identify main cycles and their internal stratigraphic architectures. Well correlation was also conducted to build well-scale stratigraphic framework. Core, logs, and well test data were integrated to understand reservoir properties and distribution. Updated Gross Deposition Environment (GDE) maps and depositional sketches were produced through the integration of seismic data analysis, the revised stratigraphic understanding and well correlation. A seismic-based revision of the existing sequence stratigraphic interpretation allowed for the identification of better-defined sequences and their systems tracts. The Habshan Formation is interpreted to comprise four main cycles (I, II, III and IV), while the Zakum Member represents one cycle (V). The seismic-based interpretation of the cycles is supported by core and log data and is in line with published data from various locations in Oman. The enhanced sequence stratigraphic understanding resulted in a better definition and prediction of reservoir development and distribution across the study area, by filling the gaps between the sparse available drilled wells. The study results allowed the identification of potential hydrocarbon plays in different stratigraphic settings, by highlighting the geometry and reservoir quality variations of each cycle. This work demonstrates the role of in-depth, refined data interpretation and integration in identifying possibly overlooked subtle traps through the understanding of sequence stratigraphic signatures in seismic and well data. The results of this work can be used as a basis for the understanding and exploration of the Habshan Fm. and other similarly stratigraphically complex formations in the study area and beyond.
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Azuma, Kisaburo, Keita Fujiwara, Satoru Kai, Akihito Otani e Osamu Furuya. "Design Margins of Fatigue Life of Carbon Steel Elbows and Tees Subjected to Reversing Dynamic Loads". In ASME 2024 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/pvp2024-123304.
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Abstract Fatigue damage is a type of cumulative damage observed in piping systems. The fatigue damage is caused by various reversing dynamic loads including seismic loads. When the reversing dynamic loads produce plastic strain in each cycle, the loading cycles cause severe damage in the component, and thus the number of cycles to failure is relatively low. This type of failure due to the severe reversing load is called low-cycle fatigue. Past research revealed that some uncertainty is generally inevitable in predicting the number of cycles to low-cycle fatigue. Hence, it is of great importance to understand the mechanism of low-cycle fatigue and to ensure an ample margin in fatigue life evaluation in piping systems. In this study, a series of shaking-table tests was carried out to study the mechanism of low-cycle fatigue and the design margin of pipe fittings. Three types of specimens were chosen as typical pipe fittings: elbows, equal tees, and reducing tees. All the specimens are made of JIS G3456 STPT370 seamless carbon steel pipe, equivalent to ASTM A106 Grade A. The response amplitudes of acceleration of each specimen were measured under the sinusoidal excitation of uniform frequency. We investigated the relation between input and output accelerations of the observed data, and then discussed the margin of pipe fittings based on the seismic design of nuclear piping systems.
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J. Liu, H., C. X. Zhao, Y. G. Wang e K. K. Shan. "A New Method of Multi-level Sedimentary Cycles Classification Based on Seismic Data". In 74th EAGE Conference and Exhibition incorporating EUROPEC 2012. Netherlands: EAGE Publications BV, 2012. http://dx.doi.org/10.3997/2214-4609.20148481.
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"Seismic Characterization of Internal Salt Cycles: remarks from the Santos Offshore Basin, Southeast Brazil." In International Congress of the Brazilian Geophysical Society&Expogef. Brazilian Geophysical Society, 2021. http://dx.doi.org/10.22564/17cisbgf2021.305.
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Heredia-Zavoni, Ernesto, Antonio Zeballos, Roberto Montes-Iturrizaga e Luis Esteva. "Bayesian Estimation of Cumulative Damage From Seismic Response Records of Buildings". In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/vib-21413.
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Abstract This paper discusses the estimation of probability distributions of damage using response records from instrumented buildings subjected to seismic excitations. The objective of the paper is to show how the information on the evolution of the mechanical properties of a system can be used to assess the state of cumulative damage. This implies expressing damage on the structural members in terms of its influence on the residual mechanical properties of the system. The information on the inelastic behavior from response records is used in a bayesian formulation along with a damage function to update prior probability distributions of damage. The damage function models the hysteretic cycles of inelastic response in terms of an initial damage and of the displacement amplitudes of the response cycles. It describes the evolution of the secant stiffness through the cycles of inelastic response as a function of cumulative damage and displacement amplitudes. The updating of probability distributions of damage for single degree of freedom systems is presented first. Extensions to the case of non-linear multi-degree of freedom systems are discussed next. Examples of reinforced concrete frames are given for illustrative purposes.
Relatórios de organizações sobre o assunto "Seismic cycles"
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Kinikles, Dellena, e John McCartney. Hyperbolic Hydro-mechanical Model for Seismic Compression Prediction of Unsaturated Soils in the Funicular Regime. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, dezembro de 2022. http://dx.doi.org/10.55461/yunw7668.
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A semi-empirical elasto-plastic constitutive model with a hyperbolic stress-strain curve was developed with the goal of predicting the seismic compression of unsaturated sands in the funicular regime of the soil-water retention curve (SWRC) during undrained cyclic shearing. Using a flow rule derived from energy considerations, the evolution in plastic volumetric strain (seismic compression) was predicted from the plastic shear strains of the hysteretic hyperbolic stress-strain curve. The plastic volumetric strains are used to predict the changes in degree of saturation from phase relationships and changes in pore air pressure from Boyle’s and Henry’s laws. The degree of saturation was used to estimate changes in matric suction from the transient scanning paths of the SWRC. Changes in small-strain shear modulus estimated from changes in mean effective stress computed from the constant total stress and changes in pore air pressure, degree of saturation and matric suction, in turn affect the hyperbolic stress-strain curve’s shape and the evolution in plastic volumetric strain. The model was calibrated using experimental shear stress-strain backbone curves from drained cyclic simple shear tests and transient SWRC scanning path measurements from undrained cyclic simple shear tests. Then the model predictions were validated using experimental data from undrained cyclic simple shear tests on unsaturated sand specimens with different initial degrees of saturation in the funicular regime. While the model captured the coupled evolution in hydro-mechanical variables (pore air pressure, pore water pressure, matric suction, degree of saturation, volumetric strain, effective stress, shear modulus) well over the first 15 cycles of shearing, the predictions were less accurate after continued cyclic shearing up to 200 cycles. After large numbers of cycles of undrained shearing, a linear decreasing trend between seismic compression and initial degree of saturation was predicted from the model while a nonlinear increasing-decreasing trend was observed in the cyclic simple shear experiments. This discrepancy may be due to not considering post shearing reconsolidation in the model, calibration of model parameters, or experimental issues including a drift in the position of the hysteretic shear-stress strain curve. Nonetheless, the trend from the model is consistent with predictions from previously- developed empirical models in the funicular regime of the SWRC. The developments of the new mechanistic model developed in this study will play a key role in the future development of a holistic model for predicting the seismic compression across all regimes of the SWRC.
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Khosravifar, Arash. COMBINED EFFECTS OF LATERAL SPREADING AND SUPERSTRUCTURE INERTIA. Deep Foundations Institute, dezembro de 2023. http://dx.doi.org/10.37308/cpf-2020-drsh-2.
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The seismic behavior of a RC pile with a diameter of 0.25 m subjected to liquefaction-induced lateral spreading was investigated using a shake table experiment that was conducted at the University of California, San Diego by Professor Ahmed Elgamal and Dr. Ahmed Ebeido (Ebeido and Elgamal 2019). A sinusoidal motion was applied at the base of a model that was inclined by 4 degrees. The loose and dense sand layers liquefied during the test, resulting in a permanent lateral spreading displacement of approximately 0.4 m (Figure E1). The pile was subjected to the combined effects of inertial loads from the acceleration of the superstructure mass and kinematic loads from the overlying nonliquefiable, dry crust. The dynamic responses of the soil and pile were analyzed to evaluate the relative contributions of inertial and kinematic loads during critical cycles (i.e., at the time of maximum inertia and the time of maximum pile strains). It was found that large pile strains developed after liquefaction was triggered. Large pile strains (and curvature) were recorded at a shallow depth within the crust (0.49 m) and a deeper location below the loose liquefiable sand (1.89 m). Large pile strains at shallow depth were found to be correlated with the inertial loads applied in the upslope direction. These upslope inertial loads were resisted by downslope crust loads, indicating an out-of-phase interaction. In contrast, large pile strains that occurred at deeper locations were correlated with downslope inertial loads and were accompanied by zero crust load, indicating that there was no lateral spreading force during the downslope inertial cycles. A gap at the downslope area in front of the pile formed because the soil displacements exceeded the pile displacements during the cyclic phase after liquefaction was triggered. The lack of crust load during the downslope inertial cycles is attributed to the pile head outrunning the crust displacement and causing the pile to be pushed into the gap at the downslope area in front of the pile. The interaction of inertia and kinematics appears to be a site- and project-specific phenomena. Therefore,the findings of this study—and, specifically, the lack of lateral spreading crust load during downslope inertial cycles—should be considered in design as one possible scenario in addition to the scenarios from several other studies that suggest combining the inertial loads with a lateral spreading force (e.g., Boulanger et al. 2007, Turner et al. 2016, Souri et al. 2022, Tokimatsu et al. 2005, Cubrinovski et al 2017).
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Ko, Yu-Fu, e Jessica Gonzalez. Effects of Low-Cycle Fatigue Fracture of Longitudinal Reinforcing Steel Bars on the Seismic Performance of Reinforced Concrete Bridge Piers. Mineta Transportation Institute, outubro de 2024. http://dx.doi.org/10.31979/mti.2024.2328.
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Earthquakes, which can cause tremendous local stress and strain on infrastructure, can cause reinforced concrete (RC) bridges to collapse due to the concrete cracking and fracture of the steel reinforcement rebars. The fracture of longitudinal reinforcing steel due to low-cycle fatigue is one of the main causes of failure in RC structures under earthquake loading. The purpose of this research is to include the effects of low-cycle fatigue fracture of longitudinal reinforcing steel bars on the seismic performance of reinforced concrete bridge piers. To obtain a greater understanding of low-cycle fatigue failure of steel reinforcement of RC bridge piers subjected to seismic loadings, its properties were studied by considering the slenderness ratio to observe its effects on the behaviors of the steel material. The slenderness ratio are functions of unsupported length, diameter of the circular cross section of the longitudinal reinforcing bars, and the spacing of transverse reinforcing bars. The seismic performance of RC single-column pier-supported bridges with flexural failure under near-fault ground motion were assessed with the use of damage indices. The damage indices can numerically assess the damaged state of RC bridge piers and show the gradual accumulation of damage. Four numerical models are developed with fiber-based nonlinear beam-column elements to simulate the damage accumulation on RC bridge piers under seismic loadings, considering variables such as low-cycle fatigue, tensile strain damage, global buckling of longitudinal steel bars, the cracking and spalling of cover concrete, and the bond-slip between concrete and longitudinal steel bars. Bond-slip is related to the interaction between the longitudinal steel rebars and the concrete for load bearing and coordination deformation. The four numerical models were developed with different considerations of low-cycle fatigue and bond-slip: Model 1 (without bond-slip and without fatigue), Model 2 (without bond-slip and with fatigue), Model 3 (with bond-slip and without fatigue), and Model 4 (with bond-slip and with fatigue). The models underwent nonlinear time-history analyses. The results were compared with experimental testing results. All four numerical models are optimal to assess the seismic performance of RC single-column pier-supported bridges. The proposed damage indices can reasonably reflect the damage states in accordance with the experimental results. The proposed models can reasonably predict the damage states and seismic behavior of RC bridge columns and could be available to the structural engineering community for non-linear analysis and performance assessment of RC bridge structures.
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Briggs, Nicholas E., e Jerome F. Hajjar. Cyclic Seismic Behavior of Concrete-filled Steel Deck Diaphragms. Department of Civil and Environmental Engineering, Northeastern University, setembro de 2023. http://dx.doi.org/10.17760/d20593269.
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Earthquake disasters in the United States account for $6.1 billion of economic losses each year, much of which is directly linked to infrastructure damage. These natural disasters are unpredictable and represent one of the most difficult design problems regarding constructing resilient infrastructure. Structural floor and roof diaphragms act as the horizontal portion of the lateral force resisting system (LFRS), distributing the seismically derived inertial loads out from the heavy concrete slabs to the vertical LFRS. Concrete-filled steel deck diaphragms are ubiquitously used in steel construction worldwide due to the ease of construction and cost-effective use of material. This report first presents a series of concrete-filled steel deck push-out tests that explores the effect of cyclic loading on the strength of steel headed stud anchors. The effect that cyclic loading has on structural performance is explored across different concrete densities, steel headed stud anchor placements and groupings, steel deck orientations, and edge conditions. As compared to prior tests, the push-out tests conducted in this work included four rows of studs along the length rather than the typical two rows, and an ability to impose cyclic loading. This provided novel insight into force flows, failure mechanisms, and load distribution between studs and stud groups. Most of the specimens also used lightweight concrete, as is common in high seismic zones.Secondly, this report describes a full-scale experimental concrete-filled steel deck diaphragm specimen which explored the cyclic behavior and capacity of this structural system. This experiment builds on previously reported experimental studies. This specimen demonstrated force distribution and flows in an indeterminant floor system and captured realistic boundary conditions and construction practices that affect the performance of this system in building structures. The results showed that concrete-filled steel deck diaphragms fail as expected and may have significant overstrength. Furthermore, a finite element framework is presented that can simulate cyclic fracture through the use of a high-fidelity steel material model. This framework was used and validated against nine experimental push-out specimens tested and documented as part of this research. The simulation capacity provides an avenue to further investigate this structural system through simulated parametric study.
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Ko, Yu-Fu, e Jessica Gonzalez. Fiber-Based Seismic Damage and Collapse Assessment of Reinforced Concrete Single-Column Pier-Supported Bridges Using Damage Indices. Mineta Transportation Institute, agosto de 2023. http://dx.doi.org/10.31979/mti.2023.2241.
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Near-fault earthquakes can have major effects on transportation systems due to the structural damage they impose on bridges. Therefore, it is imperative to assess the seismic damage of bridges appropriately, and this research focuses on reinforced concrete (RC) bridges. This research advances the seismic performance assessment of RC single-column pier-supported bridges with flexural failure under near-fault ground motion by use of ductility coefficients and damage indices. The methodology included modeling fiber-based nonlinear beam-column elements to simulate the damage development process of RC bridge piers under earthquake loadings, considering the global buckling of longitudinal steel bars, examining the cracking and spalling of cover concrete, and analyzing the effects of bond-slip. The tensile strain represented the damage of the longitudinal bars while the compression strain represented the cover concrete damage. Two innovative nonlinear fiber-based finite element models (FEMs) were developed: Model 1 (bond-slip excluded) and Model 2 (bond-slip included). Nonlinear static cyclic pushover analyses and nonlinear response history analyses were conducted. The simulation results were compared with available pseudo-dynamic test results. Model 1 provided a more ideal prognosis on the seismic performance of RC single-column pier-supported bridges under near-fault ground motion. The proposed damage indices can indicate the damage state at any stage and the gradual accumulation of damage in RC bridge piers, which are more convincing than most other indices in the literature. The proposed fiber-based nonlinear FEMs, together with the use of ductility coefficients and proposed damage indices, can also assist engineers and researchers in simulating the seismic behavior and assessing the damage state of RC bridge columns in a computationally effective manner which can empower engineers to identify and prioritize RC bridges for seismic retrofit and maintenance.
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Schiller, Brandon, Tara Hutchinson e Kelly Cobeen. Cripple Wall Small-Component Test Program: Dry Specimens (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembro de 2020. http://dx.doi.org/10.55461/vsjs5869.
Texto completo da fonteResumo:
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measures and documents seismic performance of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Three primary tasks support the earthquake loss-modeling effort. They are: (1) the development of ground motions and loading protocols that accurately represent the diversity of seismic hazard in California; (2) the execution of a suite of quasi-static cyclic experiments to measure and document the performance of cripple wall and sill anchorage deficiencies to develop and populate loss models; and (3) nonlinear response history analysis on cripple wall-supported buildings and their components. This report is a product of Working Group 4: Testing, whose central focus was to experimentally investigate the seismic performance of retrofitted and existing cripple walls. This present report focuses on non-stucco or “dry” exterior finishes. Paralleled by a large-component test program conducted at the University of California, Berkeley (UC Berkeley) [Cobeen et al. 2020], the present report involves two of multiple phases of small-component tests conducted at University of California San Diego (UC San Diego). Details representative of era-specific construction–specifically the most vulnerable pre-1960s construction–are of predominant focus in the present effort. Parameters examined are cripple wall height, finish style, gravity load, boundary conditions, anchorage, and deterioration. This report addresses all eight specimens in the second phase of testing and three of the six specimens in the fourth phase of testing. Although conducted in different testing phases, their results are combined here to co-locate observations regarding the behavior of all dry finished specimens. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto eleven cripple walls. Each specimen was 12 ft in length and 2-ft or 6-ft in height. All specimens in this report were constructed with the same boundary conditions on the top, bottom, and corners of the walls. Parameters addressed in this report include: dry exterior finish type (shiplap horizontal lumber siding, shiplap horizontal lumber siding over diagonal lumber sheathing, and T1-11 wood structural panels), cripple wall height, vertical load, and the retrofitted condition. Details of the test specimens, testing protocol (including instrumentation), and measured as well as physical observations are summarized. Results from these experiments are intended to support advancement of numerical modeling tools, which ultimately will inform seismic loss models capable of quantifying the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100 Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Mazzoni, Silvia, Nicholas Gregor, Linda Al Atik, Yousef Bozorgnia, David Welch e Gregory Deierlein. Probabilistic Seismic Hazard Analysis and Selecting and Scaling of Ground-Motion Records (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembro de 2020. http://dx.doi.org/10.55461/zjdn7385.
Texto completo da fonteResumo:
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 3 (WG3), Task 3.1: Selecting and Scaling Ground-motion records. The objective of Task 3.1 is to provide suites of ground motions to be used by other working groups (WGs), especially Working Group 5: Analytical Modeling (WG5) for Simulation Studies. The ground motions used in the numerical simulations are intended to represent seismic hazard at the building site. The seismic hazard is dependent on the location of the site relative to seismic sources, the characteristics of the seismic sources in the region and the local soil conditions at the site. To achieve a proper representation of hazard across the State of California, ten sites were selected, and a site-specific probabilistic seismic hazard analysis (PSHA) was performed at each of these sites for both a soft soil (Vs30 = 270 m/sec) and a stiff soil (Vs30=760 m/sec). The PSHA used the UCERF3 seismic source model, which represents the latest seismic source model adopted by the USGS [2013] and NGA-West2 ground-motion models. The PSHA was carried out for structural periods ranging from 0.01 to 10 sec. At each site and soil class, the results from the PSHA—hazard curves, hazard deaggregation, and uniform-hazard spectra (UHS)—were extracted for a series of ten return periods, prescribed by WG5 and WG6, ranging from 15.5–2500 years. For each case (site, soil class, and return period), the UHS was used as the target spectrum for selection and modification of a suite of ground motions. Additionally, another set of target spectra based on “Conditional Spectra” (CS), which are more realistic than UHS, was developed [Baker and Lee 2018]. The Conditional Spectra are defined by the median (Conditional Mean Spectrum) and a period-dependent variance. A suite of at least 40 record pairs (horizontal) were selected and modified for each return period and target-spectrum type. Thus, for each ground-motion suite, 40 or more record pairs were selected using the deaggregation of the hazard, resulting in more than 200 record pairs per target-spectrum type at each site. The suites contained more than 40 records in case some were rejected by the modelers due to secondary characteristics; however, none were rejected, and the complete set was used. For the case of UHS as the target spectrum, the selected motions were modified (scaled) such that the average of the median spectrum (RotD50) [Boore 2010] of the ground-motion pairs follow the target spectrum closely within the period range of interest to the analysts. In communications with WG5 researchers, for ground-motion (time histories, or time series) selection and modification, a period range between 0.01–2.0 sec was selected for this specific application for the project. The duration metrics and pulse characteristics of the records were also used in the final selection of ground motions. The damping ratio for the PSHA and ground-motion target spectra was set to 5%, which is standard practice in engineering applications. For the cases where the CS was used as the target spectrum, the ground-motion suites were selected and scaled using a modified version of the conditional spectrum ground-motion selection tool (CS-GMS tool) developed by Baker and Lee [2018]. This tool selects and scales a suite of ground motions to meet both the median and the user-defined variability. This variability is defined by the relationship developed by Baker and Jayaram [2008]. The computation of CS requires a structural period for the conditional model. In collaboration with WG5 researchers, a conditioning period of 0.25 sec was selected as a representative of the fundamental mode of vibration of the buildings of interest in this study. Working Group 5 carried out a sensitivity analysis of using other conditioning periods, and the results and discussion of selection of conditioning period are reported in Section 4 of the WG5 PEER report entitled Technical Background Report for Structural Analysis and Performance Assessment. The WG3.1 report presents a summary of the selected sites, the seismic-source characterization model, and the ground-motion characterization model used in the PSHA, followed by selection and modification of suites of ground motions. The Record Sequence Number (RSN) and the associated scale factors are tabulated in the Appendices of this report, and the actual time-series files can be downloaded from the PEER Ground-motion database Portal (https://ngawest2.berkeley.edu/)(link is external).
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Schiller, Brandon, Tara Hutchinson e Kelly Cobeen. Cripple Wall Small-Component - Test Program: Comparisons (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembro de 2020. http://dx.doi.org/10.55461/lohh5109.
Texto completo da fonteResumo:
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 4 (WG4): Testing, whose central focus was to experimentally investigate the seismic performance of retrofit and existing cripple walls. Amongst the body of reports from WG4, in the present report, a suite of four small cripple wall test phases, in total 28 specimens, are cross compared with varied exterior finishes, namely stucco (wet) and non-stucco (dry) exterior finishes. Details representative of era specific construction, specifically the most vulnerable pre-1960s construction are of predominant focus in the present effort. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto cripple walls of 12 ft in length and 2 ft or 6 ft in height. All specimens in this report were constructed with the same boundary conditions and tested with the same vertical load. Parameters addressed in this report include: wet exterior finishes (stucco over framing, stucco over horizontal lumber sheathing, and stucco over diagonal lumber sheathing); and dry exterior finishes (horizontal siding, horizontal siding over diagonal sheathing, and T1-11 wood structural panels) with attention towards cripple wall height and the retrofit condition. The present report provides only a brief overview of the test program and setup; whereas a series of three prior reports present results of test groupings nominally by exterior finish type (wet versus dry). As such, herein the focus is to cross compare key measurements and observations of the in-plane seismic behavior of all 28 specimens.
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Schiller, Brandon, Tara Hutchinson e Kelly Cobeen. Cripple Wall Small-Component Test Program: Wet Specimens II (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembro de 2020. http://dx.doi.org/10.55461/ldbn4070.
Texto completo da fonteResumo:
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 4 (WG4): Testing, whose central focus was to experimentally investigate the seismic performance of retrofitted and existing cripple walls. This report focuses stucco or “wet” exterior finishes. Paralleled by a large-component test program conducted at the University of California, Berkeley (UC Berkeley) [Cobeen et al. 2020], the present study involves two of multiple phases of small-component tests conducted at the University of California San Diego (UC San Diego). Details representative of era-specific construction, specifically the most vulnerable pre-1960s construction, are of predominant focus in the present effort. Parameters examined are cripple wall height, finish style, gravity load, boundary conditions, anchorage, and deterioration. This report addresses the third phase of testing, which consisted of eight specimens, as well as half of the fourth phase of testing, which consisted of six specimens where three will be discussed. Although conducted in different phases, their results are combined here to co-locate observations regarding the behavior of the second phase the wet (stucco) finished specimens. The results of first phase of wet specimen tests were presented in Schiller et al. [2020(a)]. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto ten cripple walls of 12 ft long and 2 or 6 ft high. One cripple wall was tested with a monotonic loading protocol. All specimens in this report were constructed with the same boundary conditions on the top and corners of the walls as well as being tested with the same vertical load. Parameters addressed in this report include: wet exterior finishes (stucco over framing, stucco over horizontal lumber sheathing, and stucco over diagonal lumber sheathing), cripple wall height, loading protocol, anchorage condition, boundary condition at the bottom of the walls, and the retrofitted condition. Details of the test specimens, testing protocol, including instrumentation; and measured as well as physical observations are summarized in this report. Companion reports present phases of the tests considering, amongst other variables, impacts of various boundary conditions, stucco (wet) and non-stucco (dry) finishes, vertical load, cripple wall height, and anchorage condition. Results from these experiments are intended to support advancement of numerical modeling tools, which ultimately will inform seismic loss models capable of quantifying the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100,Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Reis, Evan. Development of Index Buildings, (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembro de 2020. http://dx.doi.org/10.55461/fudb2072.
Texto completo da fonteResumo:
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 2: Development of Index Buildings and focuses on the identification of common variations and combinations of materials and construction characteristics of California single-family dwellings. These were used to develop “Index Buildings” that formed the basis of the PEER–CEA Project testing and analytical modeling programs (Working Groups 4 and 5). The loss modeling component of the Project (Working Group 6) quantified the damage-seismic hazard relationships for each of the Index Buildings.