A risk based PML estimation method for single-storey reinforced concrete industrial buildings and its impact on earthquake insurance rates     

Ceyhun Eren  Hilmi Luş 《Bulletin of Earthquake Engineering》2015,13(7):2169-2195

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Ground-air temperature tracking and multi-year cycles in the subsurface temperature time series at geothermal climate-change observatory     

Vladimír Čermák  Louise Bodri  Jan Šafanda  Milan Krešl  Petr Dědeček 《Studia Geophysica et Geodaetica》2014,58(3):403-424

Long-term observations of air, near-surface (soil) and ground temperatures, collected between 1994 and 2011, monitored in the Geothermal Climate Change Observatory at Spo?ilov, Prague (GCCO) are analyzed to better understand the relationship between these quantities and to describe the mechanism of heat transport at the land-atmosphere boundary layer. The 17 years long monitoring series provided a surprisingly small mean ground-air temperature offset of only 0.31 K with no clear annual course and with the offset value changing irregularly even on a daily scale. Such value is substantially lower than similar values (1–2 K and more) found elsewhere, but it may be well characteristic for a mild temperate zones, when all so far available information referred rather to more southern locations. As many other observed geophysical data, temperature time series consist of a systematic pattern (usually a set of identifiable components) contaminated by random noise, which makes the identification of the proper pattern difficult. To identify the existing systematic patterns (cycles) of the temperature-time series at several depth levels in the investigated depth interval 0–40 m, the observed data were processed with the help of the Fast Fourier Transform (FFT) and Recurrence Quantification Interval (RQI) analysis. The latter represents recently developed powerful technique to uncover hidden periodicities in a noisy time environment. At low frequency band the RQI may provide far finer resolution than the conventional FFT technique. The results proved considerable similarity for all investigated depth levels. In addition to the annual wave all measured series proved to have a more complex pattern including predominantly 8-year and 11 years long periodicities. The results were compared with similar analysis of the meteorological air temperature series as well as with the results of other similar studies. The potential dynamics explaining the occurrence of the 8-year wave is briefly discussed.  相似文献   

Distribution of secondary minerals in crusts developed on sandstone exposures          下载免费PDF全文

Zofia Alexandrowicz  Mariola Marszałek  Grzegorz Rzepa 《地球表面变化过程与地形》2014,39(3):320-335

Previous research on rock weathering crusts has revealed their large variability depending on the type of host rocks and development of weathering processes. The composition of crusts developed on natural sandstone exposures is less documented in the literature in comparison to those developed on architectonic stones. In both cases, previous research has focused mainly on the progress of salt weathering. This study considers the surfaces of sandstone tors in the Polish Outer Carpathians. The exposed parts of the rocks in this area are often covered by crust, which is up to several centimetres thick, and differs from the internal part in colour and composition. The crusts were characterized using light and electron microscopy, X‐ray diffractometry, thermal analyses, Mössbauer spectroscopy, bulk chemical analyses and sequential chemical extractions. Porosity was estimated by digital image processing. The following two hardened zones were observed: (1) thin (up to 30 µm), black, external layer, rich in carbon and composed of opal‐type silica, covered in places by sulphate incrustations and numerous spherical particles of anthropogenic origin; (2) thicker (up to several millimetres), internal part composed of a set of laminae of variable colouration, enriched in iron (oxyhydr)oxides (goethite and hematite) in comparison to the rock interior. Development of the crust results from silicon and iron redistribution during the sandstone alteration. The chief source of silica is hydrolysis of aluminosilicates, whilst that of iron is decomposition of aluminosilicates, carbonates and sulphides. Hematite is probably a result of goethite transformation. However, air pollutants may play an important role in the formation of sulphates. Silica and iron compounds affect the properties of the rock, hardening the surface and lowering porosity by formation of secondary cement. Crystallization of sulphate salts, in turn, may contribute to mechanical disintegration of the rock. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Prediction of seismic collapse risk of steel moment frame mid-rise structures by meta-heuristic algorithms     

Fooad Karimi Ghaleh Jough  Serhan Şensoy 《地震工程与工程振动(英文版)》2016,15(4):743-757

Different performance levels may be obtained for sideway collapse evaluation of steel moment frames depending on the evaluation procedure used to handle uncertainties. In this article, the process of representing modelling uncertainties, record to record (RTR) variations and cognitive uncertainties for moment resisting steel frames of various heights is discussed in detail. RTR uncertainty is used by incremental dynamic analysis (IDA), modelling uncertainties are considered through backbone curves and hysteresis loops of component, and cognitive uncertainty is presented in three levels of material quality. IDA is used to evaluate RTR uncertainty based on strong ground motion records selected by the k-means algorithm, which is favoured over Monte Carlo selection due to its time saving appeal. Analytical equations of the Response Surface Method are obtained through IDA results by the Cuckoo algorithm, which predicts the mean and standard deviation of the collapse fragility curve. The Takagi-Sugeno-Kang model is used to represent material quality based on the response surface coefficients. Finally, collapse fragility curves with the various sources of uncertainties mentioned are derived through a large number of material quality values and meta variables inferred by the Takagi-Sugeno-Kang fuzzy model based on response surface method coefficients. It is concluded that a better risk management strategy in countries where material quality control is weak, is to account for cognitive uncertainties in fragility curves and the mean annual frequency.  相似文献   

An experimental study on steel‐encased buckling‐restrained brace hysteretic dampers     

Mehmet Emrah Eryaşar  Cem Topkaya 《地震工程与结构动力学》2010,39(5):561-581

This paper describes a seismic test program performed on 12 steel‐encased buckling‐restrained braces (BRBs). The use of rolled or built‐up buckling‐restraining mechanisms with welded or bolted attachments was examined. In addition, the effects of bolt pretension, core‐to‐encasing attachment details, aspect ratio of core segment and imperfections due to manufacturing on the brace response were investigated. All specimens were subjected to a stepwise incremental quasi‐static testing protocol with a maximum axial strain amplitude of 2%. All specimens except one showed satisfactory performance with stable hysteretic response and sustained cumulative inelastic deformations in excess of 200 times the yield deformation. Based on the experimental results, the compression strength adjustment factor, and the strain hardening adjustment factor for each excursion were quantified. Test results revealed that these two factors are significantly influenced by the parameters investigated in the experimental program. BRB details were also found to influence the buckling and the yielding patterns of the core segment. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Association Between Extraterrestrial Phenomena And Weather Changes In The Northern Hemisphere In Winter     

Josef Bochníček  Pavel Hejda 《Surveys in Geophysics》2002,23(4):303-333

This paper includes a discussion of the validity of theobjections which are usuallyraised against the physical plausibility of the correlationsbetween extraterrestrialphenomena and changes in circulation in the lower atmosphere.The behaviour of the winterlower troposphere in the Northern Hemisphere was analysed bothon a month-to-month timescale and on a day-to-day time scale. The mechanisms which cansatisfactorily explainthe behaviour of the winter lower troposphere on these timescales have been described.The basic features of the results presented were explained bymeans of a mechanism basedon the propagation of planetary waves. Attention was focussedon studying the connectionsamong the changes in the pressure and temperature fields, thechanges in solar/geomagnetic activity and QBO phases by the method of composites. It hasbeen found that the compositeswithout considering QBO phases are similar to the QBO-eastpatterns under the highestactivities. Pressure deviations during QBO-west high solaractivity or low geomagneticactivity and temperature deviations during QBO-east/west lowgeomagnetic activity provedto be of negligible statistical significance.  相似文献   

On Methods for the Light Curves Extrema Determination     

Zdeněk Mikulášek  Marek Wolf  Miloslav Zejda  Petra Pecharová 《Astrophysics and Space Science》2006,304(1-4):363-365

We present two methods for the determination of moments of extrema and their errors appropriate for the analysis of light variations of variable objects. The method I is suitable for determination of times of extrema of non-periodical variables or objects, whose light curves vary. The method II is apt for O-C analyses of objects whose light curves are more or less repeating. Both methods are displayed on the analysis of BL Cam light variations and compared with the Kwee-van Woerden method.  相似文献   

The maximum acceleration and cosmology     

Pavel Voráček 《Astrophysics and Space Science》1989,159(2):181-188

The hyperbolic motion of an idealized globular particle with the Planck length radius is described by means of special relativity in order to derive an upper quantum limit of acceleration. Furthermore, it is shown that the existence of a relative acceleration can be excluded by principle. Finally, by assuming validity of Mach's principle, it is deduced that the acceleration of the rate of increase of the radius of the (closed) Universe in the Planck era, is equal, in its absolute value, to one-half of the maximum quantum limit of acceleration; the result is then shortly discussed.  相似文献   

Formulae for estimating extreme changes of lengths in spatial affine transformation     

František Charamza  Reviewer Z. Nádenik 《Studia Geophysica et Geodaetica》1973,17(2):165-169

Summary Formulae (27) and (28) which make it possible to estimate the minimum and maximum value of the deformation in length in affine transformation in space have been derived. Both values are determined by means of the elements of the given transformation matrixA without having to form the productAA ^T, or compute the corresponding eigenvalues explicitly. The derived formulae hold true under the assumption that both extreme values do not differ from each other too much.Dedicated to 90th Birthday of Professor Frantiek Fiala  相似文献   

Organische Flocculanten in Theorie und Praxis des Prager Wasserwerkes     

J. Moravec  J. Sou ek 《洁净——土壤、空气、水》1973,1(5):461-469

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