Seismic risk assessment of liquid storage tanks via a nonlinear surrogate model          下载免费PDF全文

Konstantinos Bakalis  Dimitrios Vamvatsikos  Michalis Fragiadakis 《地震工程与结构动力学》2017,46(15):2851-2868

A performance‐based earthquake engineering approach is developed for the seismic risk assessment of fixed‐roof atmospheric steel liquid storage tanks. The proposed method is based on a surrogate single‐mass model that consists of elastic beam‐column elements and nonlinear springs. Appropriate component and system‐level damage states are defined, following the identification of commonly observed modes of failure that may occur during an earthquake. Incremental dynamic analysis and simplified cloud are offered as potential approaches to derive the distribution of response parameters given the seismic intensity. A parametric investigation that engages the aforementioned analysis methods is conducted on 3 tanks of varying geometry, considering both anchored and unanchored support conditions. Special attention is paid to the elephant's foot buckling formation, by offering extensive information on its capacity and demand representation within the seismic risk assessment process. Seismic fragility curves are initially extracted for the component‐level damage states, to compare the effect of each analysis approach on the estimated performance. The subsequent generation of system‐level fragility curves reveals the issue of nonsequential damage states, whereby significant damage may abruptly appear without precursory lighter damage states.  相似文献   

From subsurface to surface: a multidisciplinary approach to decoding uplift histories in tectonically-active karst landscapes     

Christos Pennos  Stein-Erik Lauritzen  Konstantinos Vouvalidis  Patience Cowie  Sofia Pechlivanidou  Charikleia Gkarlaouni  Michael Styllas  Panagiotis Tsourlos  Antonios Mouratidis 《地球表面变化过程与地形》2019,44(9):1710-1721

We present an integrated study of subsurface and surficial karst landforms to unravel the uplift history of karst landscape in a tectonically-active area. To this end, we apply a multidisciplinary approach by combining cave geomorphology and Th/U dating of speleothems with remote sensing plus geophysical imaging of surface landforms. We use as an example Mt. Menikio in northern Greece where four caves share well-defined epiphreatic/shallow phreatic characteristics that are related to the distribution of surface and buried doline fields and provide evidence for three distinct water table stillstands (e.g. expressed as cave levels) now lying at ~130 m, ~800 m and ~1600 m a.m.s.l. Our dating constraints delimit the age of the lower water table stillstand prior to 77 ka ago and imply a maximum rate of relative base level drop of 0.45 mma^-1, which is consistent with relative tectonic uplift rate estimates along currently active normal faults. We interpret the elevation of the higher water table stillstands to reflect earlier phases of uplift related to the regional tectonic events associated with the development of the North Anatolian Fault and the Northern Aegean area. Our analysis shows that the combined study of epiphreatic/shallow phreatic caves and surficial karst landforms together, is a robust way to investigate the uplift history of a karst landscape in a tectonically-active setting. © 2019 John Wiley & Sons, Ltd.  相似文献   

Forecasting seismicity rates in western Turkey as inferred from earthquake catalog and stressing history     

Konstantinos Leptokaropoulos  Eleftheria Papadimitriou  Beata Orlecka-Sikora  Vasileios Karakostas 《Natural Hazards》2014,73(3):1817-1842

The spatio-temporal variation in seismicity in western Turkey since the late 1970s is investigated through a rate/state model, which considers the stressing history to forecast the reference seismicity rate evolution. The basic catalog was divided according to specific criteria into four subsets, which correspond to areas exhibiting almost identical seismotectonic features. Completeness magnitude and reference seismicity rates are individually calculated for each subset. The forecasting periods are selected to be the inter-seismic time intervals between successive strong (M ≥ 5.8) earthquakes. The Coulomb stress changes associated with their coseismic slip are considered, along with the constant stressing rate to alter the rates of earthquake production. These rates are expressed by a probability density function and smoothed over the study area with different degrees of smoothing. The influence of the rate/state parameters in the model efficiency is explored by evaluating the Pearson linear correlation coefficient between simulated and observed earthquake occurrence rates along with its 95 % confidence limits. Application of different parameter values is attempted for the sensitivity of the calculated seismicity rates and their fit to the real data to be tested. Despite the ambiguities and the difficulties involved in the experimental parameter value determination, the results demonstrate that the present formulation and the available datasets are sufficient enough to contribute to seismic hazard assessment starting from a point such far back in time.  相似文献   

Local and regional sources of fine and coarse particulate matter based on traffic and background monitoring     

Konstantinos Dimitriou  Pavlos Kassomenos 《Theoretical and Applied Climatology》2014,116(3-4):413-433

The aim of this study was to identify local and exogenous sources affecting particulate matter (PM) levels in five major cities of Northern Europe namely: London, Paris, Hamburg, Copenhagen and Stockholm. Besides local emissions, PM profile at urban and suburban areas of the European Union (EU) is also influenced by regional PM sources due to atmospheric transport, thus geographical city distribution is of a great importance. At each city, PM₁₀, PM_2.5, NO₂, SO₂, CO and O₃ air pollution data from two air pollution monitoring stations of the EU network were used. Different background characteristics of the selected two sampling sites at each city facilitated comparisons, providing a more exact analysis of PM sources. Four source apportionment methods: Pearson correlations among the levels of particulates and gaseous pollutants, characterisation of primal component analysis components, long-range transport analysis and extrapolation of PM size distribution ratios were applied. In general, fine (PM_2.5) and coarse (PM₁₀) particles were highly correlated, thus common sources are suggested. Combustion-originated gaseous pollutants (CO, NO₂, SO₂) were strongly associated to PM₁₀ and PM_2.5, primarily at areas severely affected by traffic. On the contrary, at background stations neighbouring important natural sources of particles or situated in suburban areas with rural background, natural emissions of aerosols were indicated. Series of daily PM_2.5/PM₁₀ ratios showed that minimum fraction values were detected during warm periods, due to higher volumes of airborne biogenic PM coarse, mainly at stations with important natural sources of particles in their vicinity. Hybrid single-particle Lagrangian integrated trajectory model was used, in order to extract 4-day backward air mass trajectories that arrived in the five cities which are under study during days with recorded PM₁₀ exceedances. At all five cities, a significantly large fraction of those trajectories were classified in short- and medium-range clusters, thus transportation of particulates along with slow moving air masses was identified. A finding that supports the assumption of long-range transport is that, at background stations, long-range transportation effects were stronger, in comparison to traffic stations, due to less local particle emissions. Short-range trajectories associated to PM transport in Stockholm, Copenhagen and Hamburg were mainly of a continental origin. All three cities were approached by slow moving air masses originated from Poland and the Czech Republic, whereas Copenhagen and Stockholm were also influenced by short-range trajectories from Germany and France and from Jutland Peninsula and Scandinavian Peninsula, respectively. London and Paris are located to the north-west part of Europe. Trajectories of short and medium length arrived to these two megacities mainly through France, Germany, UK and North Atlantic.  相似文献   

Creation of DTM with ASTER Data and Statistical Verification of the Accuracy of the Model (Western Peloponnese,Greece)     

Nikolakopoulos Konstantinos  Antonakakis Antonis 《国际地球制图》2013,28(1):3-9

Abstract

In this paper we present the use of ASTER data for the creation of a Digital Terrain Model (DMT) of high accuracy. Using a stereo pair of ASTER satellite images with 15m resolution we created two DMTs: one with a 30m pixel size and another one with a 15m pixel size. Then we made a statistical verification of the two DTMs accuracy. We created another DTM with 30m pixel size from digitized contours of 1:50000 scale topographic maps. We first made an optical comparison of the two DTMs with 30m pixel size. Then we subtracted the two DTMs and we presented their difference. Finally, we verified the DTMs accuracy using 68 points of a well‐known elevation. All the results demonstrated that DTMs derived from ASTER data have very good accuracy.  相似文献   

Calibrating a neural network‐based urban change model for two metropolitan areas of the Upper Midwest of the United States     

Bryan C. Pijanowski Corresponding author  Snehal Pithadia  Bradley A. Shellito  Konstantinos Alexandridis 《International journal of geographical information science》2013,27(2):197-215

We parameterized neural net‐based models for the Detroit and Twin Cities metropolitan areas in the US and attempted to test whether they were transferable across both metropolitan areas. Three different types of models were developed. First, we trained and tested the neural nets within each region and compared them against observed change. Second, we used the training weights from one area and applied them to the other. Third, we selected a small subset (～1%) of the Twin Cities area where a lot of urban change occurred. Four model performance metrics are reported: (1) Kappa; (2) the scale which correct and paired omission/commission errors exceed 50%; (3) landscape pattern metrics; and (4) percentage of cells in agreement between model simulations. We found that the neural net model in most cases performed well on pattern but not location using Kappa. The model performed well only in one case where the neural net weights from one area were used to simulate the other. We suggest that landscape metrics are good to judge model performance of land use change models but that Kappa might not be reliable for situations where a small percentage of urban areas change.  相似文献   

Seismic behavior of composite steel/concrete MRFs: deformation assessment and behavior factors     

Konstantinos A. Skalomenos  George D. Hatzigeorgiou  Dimitri E. Beskos 《Bulletin of Earthquake Engineering》2015,13(12):3871-3896

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Hydrochemical constraints between the karst Tabular Middle Atlas Causses and the Saïs basin (Morocco): implications of groundwater circulation     

Hélène?MicheEmail author  Ginette?Saracco  Adriano?Mayer  Khaoula?Qarqori  Mohamed?Rouai  Abdelilah?Dekayir  Konstantinos?Chalikakis  Christophe?Emblanch 《Hydrogeology Journal》2018,26(1):71-87

The karst Tabular Middle Atlas Causses reservoir is the main drinking-water supply of Fez-Meknes region (Saïs Basin) in Morocco. Recent analyses showed a decline in associated groundwater chemical quality and increased turbidity. To understand this hydrosystem, four surveys were undertaken during fall and spring, 2009–2011. Hydrogeochemical studies coupled with isotopic analyses (δ¹⁸O, δD and ²²²Rn) showed that the aquifers between the causses (mountains) and the Saïs Basin are of Liassic origin and at the southern extremities are of Triassic origin. Five recharge zones of different altitudes have been defined, including two main mixing zones in the south. Deuterium excess results suggest local recharge, while a plot of δ¹⁸O versus δD characterizes a confined aquifer in the eastern sector. ²²²Rn results reveal areas of rapid exchanges with an upwelling time of less than 2 weeks. A schematic conceptual model is presented to explain the groundwater circulation system and the behavior of this karst system.  相似文献   

Quaternary climate change and Heinrich events in the southern Balkans: Lake Prespa diatom palaeolimnology from the last interglacial to present   总被引：1，自引：0，他引：1  

Aleksandra Cvetkoska  Zlatko Levkov  Jane M. Reed  Bernd Wagner  Konstantinos Panagiotopoulos  Melanie J. Leng  Jack H. Lacey 《Journal of Paleolimnology》2015,53(2):215-231

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From free good to commodity: Universalizing the provision of water in Paris (1830–1930)     

Denis Bocquet  Konstantinos Chatzis  Agnès Sander 《Geoforum》2008,(6):1821-1832

This article focuses on the water distribution network in Paris, from the 1830s, when most Parisians got their water from public fountains and private wells, to the 1930s, by which time almost all of the capital’s inhabitants had been connected to the same network and enjoyed a standard service. It contributes, by a detailed analysis of the entire chain of mediators and mediation, to specify how the modern infrastructure ideal actually took form. In that aim, we analyze the manner in which each actor (public as well as private), in accordance with his/her constraints and resources, which depend on his/her position in the social space, was able to conceive of his/her environment, define objectives, confront problems, make choices and deploy a whole range of frequently innovative practices. In order to understand the underlying factors, our task consists in identifying the actors, modi operandi, progress and phases involved in universalizing water services. Spatially analyzing the extension of the water network, this article demonstrates that the process of universalization, far from being the inexorable and linear outcome of the action of a small number of “major historical forces”, was the upshot of the actions of a whole range of actors acting in specific different geographical, social, economic and technical contexts. The achievement of the “modern infrastructural ideal” as a macro-social phenomenon was ultimately down to a long accumulation process of a multitude of actions, interactions, conflicts and learning processes.  相似文献