Seismic response of 20‐story base‐isolated and fixed‐base reinforced concrete structural wall buildings at a near‐fault site          下载免费PDF全文

Vladimir Calugaru  Marios Panagiotou 《地震工程与结构动力学》2014,43(6):927-948

This paper investigates numerically the seismic response of six seismically base‐isolated (BI) 20‐story reinforced concrete buildings and compares their response to that of a fixed‐base (FB) building with a similar structural system above ground. Located in Berkeley, California, 2 km from the Hayward fault, the buildings are designed with a core wall that provides most of the lateral force resistance above ground. For the BI buildings, the following are investigated: two isolation systems (both implemented below a three‐story basement), isolation periods equal to 4, 5, and 6 s, and two levels of flexural strength of the wall. The first isolation system combines tension‐resistant friction pendulum bearings and nonlinear fluid viscous dampers (NFVDs); the second combines low‐friction tension‐resistant crosslinear bearings, lead‐rubber bearings, and NFVDs. The designs of all buildings satisfy ASCE 7‐10 requirements, except that one component of horizontal excitation, is used in the 2D nonlinear response history analysis. Analysis is performed for a set of ground motions scaled to the design earthquake and to the maximum considered earthquake (MCE). At both the design earthquake and the MCE, the FB building develops large inelastic deformations and shear forces in the wall and large floor accelerations. At the MCE, four of the BI buildings experience nominally elastic response of the wall, with floor accelerations and shear forces being 0.25 to 0.55 times those experienced by the FB building. The response of the FB and four of the BI buildings to four unscaled historical pulse‐like near‐fault ground motions is also studied. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

从土壤腐殖质分组到分子有机质组学认识土壤有机质本质   总被引：2，自引：0，他引：2  

潘根兴  丁元君  陈硕桐  孙景玲  冯潇  张晨  Marios Doross  郑聚锋  张旭辉  程琨  刘晓雨  卞荣军  李恋卿 《地球科学进展》2019,(5):451-470

梳理了与土壤生态系统功能相联系的,特别是对固碳减排的土壤有机质本质认识的研究进展及路径,探讨了经典腐殖质学说存在的问题,概述了新近的有机质保护稳定学说及腐殖质组学学说,并追溯了生物标志物有机质分子研究,最后从土壤学的基本理念和理论出发讨论和重新认识土壤有机质的本质及其价值。从形成条件、分离条件和分子鉴定等多方面分析,土壤腐殖质形成和稳定学说越来越显示出局限性;而面向气候变化的碳固定研究可以深入探析土壤有机质的复杂存在状态。越来越认识到土壤有机质是投入土壤的有机物质经不同程度生物利用或降解的产物残留,只是被土壤不同程度地区隔和封闭,本质上仍是分子量变化极大的生命源有机物的集合。因此,可通过生物标志物分子作为靶标在土壤中提取和识别,该技术的发展将孕育萌生土壤有机质分子组学。后者可以用于判读土壤有机质的结构支撑、反应活性和促生功能等方面的本质差别,这些差别可能是由有机分子组成结构及存在状态所决定而不是由有机分子稳定性决定的。从这个概念出发,类似于土壤微生物分子生态,土壤有机质的丰度、组成、结构与功能间的联系可能是土壤有机质本质的核心问题。对这种关系的量化和参数化表征可用以探索土壤有机质永续固定,且可以保持生命活性的土壤有机质的管理策略及技术,并配合土壤的团聚体理论诠释土壤的本质和生态系统功能服务,这将是未来土壤学服务人类可持续发展的理论立足点。  相似文献   

An improved model for contraction of dark matter haloes in response to condensation of baryons     

Marios Kampakoglou 《Monthly notices of the Royal Astronomical Society》2006,369(4):1988-1994

The cooling of gas in the centres of dark matter haloes is expected to lead to a more concentrated dark matter distribution. The response of dark matter to the condensation of baryons is usually calculated using the model of adiabatic contraction, which assumes spherical symmetry and circular orbits. Following Gnedin et al., we improve this model by modifying the assumed invariant from M ( r ) r to     , where r and     are the current and orbit-averaged particle positions. We explore the effect of the bulge in the inner regions of the halo for different values of the bulge-to-disc mass ratio. We find that the bulge makes the velocity curve rise faster in the inner regions of the halo. We present an analytical fitting curve that describes the velocity curve of the halo after dissipation. The results should be useful for dark matter detection studies.  相似文献   

Optimized earthquake response of multi‐storey buildings with seismic isolation at various elevations     

Dimos C. Charmpis  Petros Komodromos  Marios C. Phocas 《地震工程与结构动力学》2012,41(15):2289-2310

The response of multi‐storey structures can be controlled under earthquake actions by installing seismic isolators at various storey levels. By vertically distributing isolation devices at various elevations, the designer is provided with numerous options to appropriately adjust the seismic performance of a building. However, introducing seismic isolators at various storey levels is not a straightforward task, as it may lead to favourable or unfavourable structural behaviour depending on a large number of factors. As a consequence, a rather chaotic decision space of seismic isolation configurations arises, within which a favourable solution needs to be located. The search for favourable isolators' configurations is formulated in this work as a single‐objective optimization task. The aim of the optimization process is to minimize the maximum floor acceleration of the building under consideration, while constraints are specified to control the maximum interstorey drift, the maximum base displacement and the total seismic isolation cost. A genetic algorithm is implemented to perform this optimization task, which selectively introduces seismic isolators at various elevations, in order to identify the optimal configuration for the isolators satisfying the pre‐specified constraints. This way, optimized earthquake response of multi‐storey buildings can be obtained. The effectiveness of the proposed optimization procedure in the design of a seismically isolated structure is demonstrated in a numerical study using time‐history analyses of a typical six‐storey building. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The statistics of wave height and crest elevation during the December 2012 storm in the North Sea     

Richard Gibson  Marios Christou  Graham Feld 《Ocean Dynamics》2014,64(9):1305-1317

This paper concerns new field measurements of wave height and crest elevation probability distributions as measured in the North Sea during a storm in December 2012. The water surface elevation was recorded by Saab WaveRadar REX instruments mounted on eight fixed-jacket platforms in addition to a Datawell Directional Waverider buoy. The storm generated an easterly sea state which peaked well in excess of the 100-year wave height for that direction in the region. Furthermore, 19 freak waves occurred during the storm according to the definition as reported by Haver (2000). The present study demonstrates that the significant steepness and spectral bandwidth during the storm remain almost constant. Consequently, there is little change in the commonly applied design wave height and crest elevation probability distributions throughout the storm. Whilst the bulk of the recorded data was in good agreement with the theoretical distributions, it was demonstrated that when the wind speed was larger than 25 m/s, the measured crest elevation lies above the second-order Forristall distribution.  相似文献   

Exploring the Nature of Soil Organic Matter from Humic Substances Isolation to SOMics of Molecular Assemblage   总被引：4，自引：0，他引：4  

Genxing Pan  Yuanjun Ding  Shuotong Chen  Jingling Sun  Xiao Feng  Chen Zhang  Doross Marios  Jufeng Zheng  Xuhui Zhang  Kun Cheng  Xiaoyu Liu  Rongjun Bian  Lianqing Li 《地球科学进展》2019,34(5):451-470

In this review, the evolution of Soil Organic Matter (SOM) research was traced back to outline the main achievement of understanding SOM in relation to its ecological functioning, particularly of carbon sequestration against climate change. The short-coming of soil humus theory, knowledge of SOM protection and stabilization, framework of newly emerged Humeomics as well as the increasingly active study of molecular organics in soils were analyzed and discussed, highlighting the importance of re-visiting SOM in term of structure-property-functions for the main mission of modern soil science. There were limitations of soil forming conditions, fraction separation procedure and single molecule identification for understanding the huge complex humus of larger sized synthesized molecules. Thanks to the ever-active studies of soil (organic) carbon sequestration and stabilization focusing on the association status of SOM with soil components, SOM has been increasingly recognized as an assemblage of metabolites from life activities on or in soil, with different allocation or protected in mineral/organic complex phases, which could be traced by biomarker molecules. Using such biomarker molecules as a target (like primer in molecular microbiology), all the molecules of SOM could be digested and isolated for qualitative or quantitative identification with GC/MS high resolution technologies. Such development has emerged a new paradigm of molecular SOM study, finally as SOMics as a modern soil science frontier. The functioning of SOM for stabilizing soil structure, enhancing reactivity and promoting biological resistance could be correlated to the paradigm of abundance, composition, structure and functions rather than the content and recalcitrance of SOM. This may deserve urgent studies to quantify and parameterize the defined paradigm based on the molecular composition of SOM. Again, such theory and technology development could provide a tool to manage SOM in term of carbon sequestration but revalorizing bioactivity in ecosystems, especially in agroecosystems. We believe such studies could rather depict the nature of SOM and of soil in relation to its ecological services and functioning, which will be the focus of soil science in serving the sustainable development of human society.  相似文献   

Interactions between groundwater and surface water: the state of the science   总被引：37，自引：6，他引：37  

Marios Sophocleous 《Hydrogeology Journal》2002,10(1):52-67

The interactions between groundwater and surface water are complex. To understand these interactions in relation to climate, landform, geology, and biotic factors, a sound hydrogeoecological framework is needed. All these aspects are synthesized and exemplified in this overview. In addition, the mechanisms of interactions between groundwater and surface water (GW–SW) as they affect recharge–discharge processes are comprehensively outlined, and the ecological significance and the human impacts of such interactions are emphasized. Surface-water and groundwater ecosystems are viewed as linked components of a hydrologic continuum leading to related sustainability issues. This overview concludes with a discussion of research needs and challenges facing this evolving field. The biogeochemical processes within the upper few centimeters of sediments beneath nearly all surface-water bodies (hyporheic zone) have a profound effect on the chemistry of the water interchange, and here is where most of the recent research has been focusing. However, to advance conceptual and other modeling of GW–SW systems, a broader perspective of such interactions across and between surface-water bodies is needed, including multidimensional analyses, interface hydraulic characterization and spatial variability, site-to-region regionalization approaches, as well as cross-disciplinary collaborations. Electronic Publication  相似文献   

Neural network analysis of overturning response under near-fault type excitation     

Nikos Gerolymos  Marios Apostolou  George Gazetas 《地震工程与工程振动(英文版)》2005,(2)

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The Origin and Evolution of Safe-Yield Policies in the Kansas Groundwater Management Districts   总被引：1，自引：0，他引：1  

Sophocleous  Marios 《Natural Resources Research》2000,9(2):99-110

The management of groundwater resources in Kansas continues to evolve. Declines in theHigh Plains aquifer led to the establishment of groundwater management districts in themid-1970s and reduced streamflows prompted the enactment of minimum desirable streamflowstandards in the mid-1980s. Nonetheless, groundwater levels and streamflows continued todecline, although at reduced rates compared to premid-1980s rates. As a result, safe-yieldpolicies were revised to take into account natural groundwater discharge in the form of streambaseflow. These policies, although a step in the right direction, are deficient in several ways.In addition to the need for more accurate recharge data, pumping-induced streamflow depletion,natural stream losses, and groundwater evapotranspiration need to be accounted for in therevised safe-yield policies. Furthermore, the choice of the 90% flow-duration statistic as ameasure of baseflow needs to be reevaluated, as it significantly underestimates mean baseflowestimated from baseflow separation computer programs; moreover, baseflow estimation needsto be refined and validated.  相似文献   

Groundwater recharge and sustainability in the High Plains aquifer in Kansas, USA   总被引：8，自引：6，他引：2  

Marios Sophocleous 《Hydrogeology Journal》2005,13(2):351-365

Sustainable use of groundwater must ensure not only that the future resource is not threatened by overuse, but also that natural environments that depend on the resource, such as stream baseflows, riparian vegetation, aquatic ecosystems, and wetlands are protected. To properly manage groundwater resources, accurate information about the inputs (recharge) and outputs (pumpage and natural discharge) within each groundwater basin is needed so that the long-term behavior of the aquifer and its sustainable yield can be estimated or reassessed. As a first step towards this effort, this work highlights some key groundwater recharge studies in the Kansas High Plains at different scales, such as regional soil-water budget and groundwater modeling studies, county-scale groundwater recharge studies, as well as field-experimental local studies, including some original new findings, with an emphasis on assumptions and limitations as well as on environmental factors affecting recharge processes. The general impact of irrigation and cultivation on recharge is to appreciably increase the amount of recharge, and in many cases to exceed precipitation as the predominant source of recharge. The imbalance between the water input (recharge) to the High Plains aquifer and the output (pumpage and stream baseflows primarily) is shown to be severe, and responses to stabilize the system by reducing water use, increasing irrigation efficiency, adopting water-saving land-use practices, and other measures are outlined. Finally, the basic steps necessary to move towards sustainable use of groundwater in the High Plains are delineated, such as improving the knowledge base, reporting and providing access to information, furthering public education, as well as promoting better understanding of the publics attitudinal motivations; adopting the ecosystem and adaptive management approaches to managing groundwater; further improving water efficiency; exploiting the full potential of dryland and biosaline agriculture; and adopting a goal of long-term sustainable use.

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Resumen El uso sostenible de aguas subterráneas debe garantizar tanto que el recurso futuro no esté amenazado por sobreutilización como que los ambientes naturales dependientes del recurso sean protegidos (ie el flujo base de los arroyos, la vegetación ripariana, los ecosistemas acuáticos y los pantanos). El manejo adecuado de los recursos de aguas subterráneas requiere información precisa con respecto a los influjos (recarga) y descargas (bombeo y descarga natural) en cada cuenca de aguas subterráneas de tal manera que se pueda estimar o reevaluar el comportamiento de largo plazo del acuífero y su tasa de sotenibilidad. En un primer paso hacia esta meta, este trabajo destaca algunos estudios claves de recarga de aguas subterráneas en las llanuras altas de Kansas. Dichos estudios se concentran en diferentes escalas: estudios regionales del presupuesto para aguas del suelo y modelos de aguas subterráneas, estudios de recarga de aguas subterráneas a nivel provincial y estudios locales experimentales de terrenos que incluyen algunos interesantes descubrimientos nuevos. Estas investigaciones comparten el énfasis en los presupuestos de partida y las limitaciones así como en los factores ambientales que afectan los procesos de recarga. El impacto general de las irrigaciones y cultivos sobre la recarga es un obvio incremento en el monto de recarga y en muchos casos excede a la precipitación como la fuente principal de recarga. Se puede observar que el desequilibrio entre el influjo de agua (recarga) del acuífero de las llanuras altas y la descarga (bombeo y flujos base de los arroyos principalmente) es severo. Asimismo, se describen las respuestas para estabilizar el sistema a través de la reducción del uso de agua por medio del incremento de la eficiencia de las irrigaciones y de la adopción de las prácticas de ahorro de agua y del uso de tierras así como otras medidas adicionales. Finalmente se describen los pasos básicos necesarios para evolucionar hacia el uso sostenible de las aguas subterráneas en las llanuras altas de Kansas. Estos pasos están constituidos por una mejora del conocimiento base, comunicar y proporcionar fácil acceso a la información, mejorar el conocimiento público general así como promover un mejor entendimiento de las motivaciones para las actitudes de la comunidad, adoptar los enfoques administrativos de ecosistemas y administración adaptable en el manejo de las aguas subterráneas, continuar las mejoras del uso eficiente del agua, explotar el potencial de la agricultura de terrenos áridos y biosalina y adoptar como meta el uso sostenible a largo plazo.

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Résumé Lutilisation durable de leau souterraine doit permettre non seulement que la pérennité de leau ne soit pas menacée, mais aussi que les environnements naturels qui dépendent de cette ressource, tels que la végétation riveraine, les écosystemes aquatiques et les milieux humides, soient protégés. Afin dassurer une gestion appropriée des ressources en eau souterraine, une information précise concernant les entrées (recharge) et les sorties (décharge naturelle et pompage) deau dans chacun des bassins est nécessaire afin que le comportement à long terme de laquifère et le taux de pompage durable puissent être estimés. En guise dinitiative, ce travail illustre certaines études clé concernant la recharge de leau souterraine à plusieurs échelles dans les hautes plaines du Kansas. Ces études comprennent le bilan sol-eau et la modélisation numérique à léchelle régionale, létude de la recharge des nappes souterraines à léchelle du comté, des études expérimentales à petite échelle et certaines découvertes originales. Lors de la présentation de ces études, lemphase est portée sur les hypothèses et limitations ainsi que sur les facteurs environmentaux qui affectent les processus de recharge. En général, les effets de lirrigation et de lagriculture sur la recharge sont daugmenter considérablement le taux de recharge, et dans plusieurs cas, dexcéder les précipitations comme principale source de recharge. Le déséquilibre entre les intrants deau (recharge) et entrants (pompage et écoulement de base dans les rivières) dans laquifère des hautes plaines est très important. Les résultats des efforts de stabilisation du système aquifère en diminuant lutilisation deau, en améliorant lefficacité des techniques dirrigation, en adoptant des pratiques dutilisation du territoire qui réduisent lutilisation deau et en adoptant certaines autres mesures sont présentés. Enfin, les étapes de base nécessaires afin datteindre une utilisation durable de leau souterraine dans les hautes plaines sontexposées. Elles comprennent lamélioration des connaissance de base, lapromotion dune meilleure compréhension de la motivation et de lattitudedu public, ladoption dune approche de gestion de leau souterraineadaptable et basée sur les écosystèmes, lamélioration de lefficacitédutilisation de leau, lexploitation du plein potentiel de lagriculturebiosaline et en milieu aride, et ladoption dun objectif pourlutilisation durable à long terme.

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