Behavior of moment‐resisting frame structures subjected to near‐fault ground motions     

Babak Alavi  Helmut Krawinkler 《地震工程与结构动力学》2004,33(6):687-706

Near‐fault ground motions impose large demands on structures compared to ‘ordinary’ ground motions. Recordings suggest that near‐fault ground motions with ‘forward’ directivity are characterized by a large pulse, which is mostly orientated perpendicular to the fault. This study is intended to provide quantitative knowledge on important response characteristics of elastic and inelastic frame structures subjected to near‐fault ground motions. Generic frame models are used to represent MDOF structures. Near‐fault ground motions are represented by equivalent pulses, which have a comparable effect on structural response, but whose characteristics are defined by a small number of parameters. The results demonstrate that structures with a period longer than the pulse period respond very differently from structures with a shorter period. For the former, early yielding occurs in higher stories but the high ductility demands migrate to the bottom stories as the ground motion becomes more severe. For the latter, the maximum demand always occurs in the bottom stories. Preliminary regression equations are proposed that relate the parameters of the equivalent pulse to magnitude and distance. The equivalent pulse concept is used to estimate the base shear strength required to limit story ductility demands to specific target values. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Sweden     

Helmut Goerke  Gerhard Eder  Kurt Weber  Wolfgang Ernst 《Marine pollution bulletin》1979,10(5):127-132

Four invertebrate and one fish species (Cerastoderma edule, Mya arenaria, Arenicola marina, Crangon crangon, Solea solea) from a single area of the German Wadden sea were investigated for concentrations of ten organochlorine pollutants in 1976. PCB concentrations (wet tissue basis) were predominating with 10–200 ng g^?1, while p,p′-DDD, dieldrin, α-HCH, γ-HCH and p,p′-DDE generally ranged between 1 and 10 ng g^?1. Values of α-endosulfan were even lower; p,p′-DDT, endrin and heptachlor epoxide could not be detected. Residue levels in shrimps were close to the lower range of values which have been found in this species from other areas of the North Sea since 1974. The patterns of residue concentrations in the five aquatic species were remarkably different indicating species- and compound-specific bioaccumulation. Trophic level and lipid content were shown to be responsible for PCB concentrations increasing from bivalves to fish.  相似文献   

Experimentelle Bildung von SiO2-Mineralien aus natürlichen Silikaten und silikatischen Gesteinen bei 180° C     

Helmut Höller 《Contributions to Mineralogy and Petrology》1968,17(3):187-203

Zusammenfassung Bei einer Temperatur von 180°C wurde die Umwandlung eines Trachyandesites sowie eines Serpentins in Quarz im alkalischen Milieu untersucht.Die Bildung der SiO₂-Mineralien erfolgte aus den silikatischen Gemengteilen dieser Gesteine, wie auch Versuche mit Alkalifeldspat, Plagioklas, Augit und Biotit zeigen.Unter dem Einfluß von verschiedenen KOH- und NaOH-Lösungen kam es zu einem Abbau der silikatischen Substanzen und zur Bildung von Cristobalit und dann erst von Quarz.Bei geringeren Alkalikonzentrationen bleibt der Cristobalit sehr lange erhalten; bei höheren Konzentrationen dagegen kommt es zu einer raschen Bildung von Quarz. Es zeigt sich dabei, daß die NaOH-Lösungen die Quarzbildung stärker beschleunigen als die KOH-Lösungen. Die experimentell zu SiO₂-Mineralien umgewandelten Trachyandesite konnten mit den natürlichen opalisierten Trachyandesiten verglichen werden.Auch aus Cristobalit und Alunit bestehende natürliche Zersetzungsprodukte des Trachyandesites konnten experimentell nachgebildet werden. Dies geschah durch die Einwirkung von alkalischen Lösungen und darauffolgend von Schwefelsäure auf den Trachyandesit.

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Experimental formation of SiO₂-minerals out of natural silicates and silicatic rocks at 180° C

The transformation of both trachyandesite and serpentine into quartz in alcalic surroundings at 180° C was investigated by experiments. The SiO₂-minerals were formed out of the silicatic components of the rocks (trachyandesite and serpentine), as was shown by experiments with potassium feldspar, oligoclase, augite and biotite. Under the influence of differing KOH and NaOH solutions the silicatic substances were dissolved, and cristobalite at first, and only afterwards quartz were formed. At low alcalic concentrations the cristobalite was preserved for a long time whereas higher alcalic concentrations led to a rapid formation of quartz. The NaOH-solutions speeded up the formation of quartz to a greater extent than KOH-solutions. The trachyandesite, experimentally transformed into SiO₂-minerals, could be compared with the naturally opalized trachyandesites. Products of natural alteration consisting of cristobalite and alunite could likewise be imitated in experiments, when the trachyandesite was transformed first by alcalic solutions and then by sulphuric acid.

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Herrn Professor Dr. H. Heritsch danke ich für sein dauerndes Interesse an dieser Arbeit, für Ratschläge und kritische Bemerkungen sowie dafür, daß die Experimente am Institut für Mineralogie und Petrographie der Universität Graz durchgeführt werden konnten. Herrn Professor Dr. C. W. Correns danke ich für wertvolle Hinweise und für die Möglichkeit, die experimentelle Technik in Göttingen anläßlich eines Studienaufenthaltes kennenzulernen. Ebenso gilt mein Dank Herrn Professor Dr. K. H. Wedepohl. Ferner danke ich Frl. Dr. A. Heydemann für anregende Diskussionen. Herrn Dr. F. Grasenick, dem Leiter des Forschungszentrums für Elektronenmikroskopie der Hochschulen in der Steiermark, verdanke ich die elektronenmikroskopischen Aufnahmen.  相似文献   

Book review     

Helmut Moritz  Hermann Drewes 《Journal of Geodesy》1987,61(3):XXVII-XXX

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Man's impact on the evolution of the physical environment in the Mediterranean region in historical times     

Dr. Helmut Brückner 《GeoJournal》1986,13(1):7-17

Holocene fluvial and marine sediments have been found in many areas of the Mediterranean region. In Basilicata, for example, four periods of accumulation can be identified. Only the first one was climatically/eustatically caused, whereas the other three — dating from the Greek-Roman Epoch, the medieval times, and the last two centuries — owe their origin to man's activities (deforestation, farming etc.).The ecologically vulnerable environment (Mediterranean subtropics, easily erodable marls and clays, steep relief) was the main reason why man's influence on nature has had catastrophic effects (badland formation in the hinterland and on the valley slopes, enormous accumulations in the valleys and coastal plains).Extended form of a paper presented during the Main Session of the 25^th International Geographical Congress of the International Geographical Union in Paris in 1984.  相似文献   

Einige Beobachtungen und Überlegungen zur Kluftentstehung in Sedimentgesteinen     

Dipl.-Geol. Dr.-Ing. Helmut Bock 《International Journal of Earth Sciences》1976,65(1):83-101

Zusammenfassung Ruhig gelagerte Sedimentgesteine eignen sich im besonderen Maße für grundsätzliche Untersuchungen zur Kluftentstehung. Die Klüftung erreicht nämlich ihre größte Regelmäßigkeit und Vollendung in Gebieten mit nahezu horizontal liegenden Sedimentgesteinen, in denen andere tektonische Strukturen kaum oder überhaupt nicht auftreten (Secor, 1965: 634).In den untersuchten, annähernd horizontal gelagerten, geschichteten Sedimentgesteinen Südwestdeutschlands sind zwei Kluftscharen entwickelt, die normal zueinander sowie normal zu den Schichtflächen stehen. Die Kluftscharen sind hinsichtlich Streuung, Rauhigkeit, Kluftabstand und Durchtrennungsgrad ungleichwertig entwickelt. Diese ungleiche Entwicklung läßt sich sowohl in den kompetenten (Kalk-, Sandsteine) als auch in den inkompetenten (Mergel, Tonstein) Schichten beobachten.Mit Hilfe experimenteller und rechnerischer Untersuchungen wird versucht, eine mechanisch sinnvolle Erklärung des geologischen Sachverhaltes zu finden. Eine wesentliche Rolle spielt dabei die Tatsache, daß das Gebirge hinsichtlich der in ihm entwickelten Klüfte als ein inhomogener, geschichteter Körper anzusehen ist. Es läßt sich zeigen, daß die beobachteten natürlichen und künstlichen Kluftsysteme am besten erklärt werden können, wenn die größte Hauptnormalspannung als vertikal gerichtet angenommen wird. Entscheidend für die gerichtete Anlage der Kluftstrukturen sind (zum Teil nur geringfügige) Betragsdifferenzen der zwei horizontal gerichteten kleineren Normalspannungen.

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Smoothly layered sedimentary rocks are particularly suited for fundamental investigations on joint generation, because jointing reaches its ultimate regularity and perfection in areas of near-horizontal sedimentary strata where other types of structural deformation are scare or absent (Secor, 1965: 634).The near-horizontal, stratified sedimentary rocks of southwest-Germany are investigated where two joint sets are developed in a position approximately normal to each other and normal to the bedding planes. The joint sets are nonsimilar in variance of joint orientation, asperities, joint spacing, and degree of separation. This nonsimilar development of the joint sets can be observed in competent layers (limestones, sandstones) as well as in incompetent ones (marls, claystones).It is attempted to find a mechanically efficient interpretation of the observed joint system by means of arithmetical and experimental investigations. It is important hereby that due to its jointing the rock mass has the property of an inhomogeneous, layered body. It can be shown, that the natural joint systems are in agreement with the artificially produced fracture pattern only in the case, when the major principal stress is in vertical direction. Partly only small differences in magnitude between the horizontally directed intermediate and minor princjpal stresses are decisive for the systematic arrangement of the joints.

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Résumé Les roches sédimentaires en gisement calme se prêtent particulièrement bien à des recherches sur la genèse des diaclases. Ce système de joints atteint en effet sa «régularité et sa perfection les plus grandes dans les régions à roches sédimentaires horizontales ou presque, dans lesquelles d'autres structures tectoniques n'apparaissent pas ou guère» (Secor, 1965: 634).Dans les roches sédimentaires presqu'horizontales étudiées en Allemagne du Sud, deux groupes de diaclases parallèles se sont développés perpendiculairement l'un par rapport à l'autre ainsi que par rapport aux plans de stratification. Ces groupes de diaclases parallèles se sont développés inégalement quant à leur dispersion, leur rugosité, leur écartement et leur ouverture. Ce développement inégal peut s'observer à la fois dans les couches «compétentes» (calcaires, grès) et dans les couches «incompétentes» (marnes, argilites).A l'aide de calculs et de recherches expérimentales, on a tenté de trouver une explication mécaniquement plausible de ce comportement géologique. Le rôle essentiel joué dans ce cas est celui de la chaîne qui doit être considérée du point de vue des diaclases comme un corps stratifié non homogène. On peut montrer que les systèmes naturels et artificiels de diaclases observés peuvent le mieux s'expliquer si l'on accepte que la contrainte normale principale la plus forte est orientée verticalement. Des différences (en partie même faibles) entre les deux contraintes normales mineures orientées horizontalement sont décisives pour l'orientation structurale des systèmes de diaclases.

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. « , , » (SECOR, 1965). - : , , , . , , . , «» (kompetenten) -, -, « » (inkompetenten)-, — . . , , . , , , . .

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Temperaturen und Drucke bei der regionalen Metamorphose: Prinzipielle und praktische Hinweise     

Prof. Dr. Helmut G. F. Winkler 《International Journal of Earth Sciences》1976,65(1):874-885

The author's concept (1970, 1974) of evaluating metamorphic conditions is explained on the basis of most recent petrologic data. The major points treated are:

1. Instead of usual petrographic mapping, petrographic work in the field is aimed at specific “targets”, i.e., rock compositions. This is so because only specific rocks may give petrogenetically relevant information in the four metamorphic grades.
2. There are very many mineral reactions in metamorphism but only a few are petrogenetically significant. These are important to know, and they are graphically demonstrated. Any mineral assemblage that is formed by a significant mineral reaction must be verified as a paragenesis of mutually contacting minerals. Only such parageneses deserve to be mapped in the field as isograds or isoreactiongrads.
3. Crossing isograds or isoreactionsgrads provide data on temperature and pressure during metamorphism for that part of a metamorphic terrane where the crossing has been observed.
4. The sequence of isograds or isoreaction-grads may be a pressure indicator. Moreover, such a sequence provides geodynamic information whether a larger metamorphic area has been lifted up evenly or has been tilted while it was uplifted after metamorphism.

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The genesis of the methane in Lake Kivu (Central Africa)     

Dr. Klaus Tietze  Dr. Mebus Geyh  Dr. Helmut Müller  Dr. Lothar Schröder  Dr. Wolfgang Stahl  Dr. Hermann Wehner 《International Journal of Earth Sciences》1980,69(2):452-472

Large amounts of methane and carbon dioxide, among other gases, are dissolved in the deep water of Lake Kivu. There is no dispute about the primarily magmatic origin of the carbon dioxide, but models of the genesis of the methane have been contradictory up to now. They have been based on too few and partly too inaccurate data.On the basis of new measurements obtained from gas and sediment samples, some of the old concepts have been further developed to a new model. According to this model, the methane is generated mainly by bacteria from the organic carbon of the sediment. It probably also contains minor amounts of thermocatalytic methane.About 70% of the organic carbon of the upper sediment is derived from mainly magmatic carbon dioxide (old carbon), which enters the biozone of the lake from the deep water by eddy diffusion and is assimilated there. The remaining 30% comes from atmospheric carbon dioxide (young carbon) assimilated in the biozone. But because methane also migrates into the lake from deeper sediment, the¹⁴C-content in the methane dissolved in the lake water is not 30% modern but only ca. 10% modern.More isotopic measurements on plankton, methane, carbon dioxide and sediment samples are necessary to support this model.

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Zusammenfassung Im Tiefenwasser des Kivusees sind u. a. große Mengen an Methan und Kohlendioxid gelöst. Während über den hauptsächlich magmatischen Ursprung des Kohlendioxids weitgehend Einigkeit besteht, sind die bisherigen Modellvorstellungen zur Genese des Methans widersprüchlich. Sie beruhen auf zu wenigen und zum Teil zu ungenauen Meß-daten.Mit Hilfe neuer Meßergebnisse an Gas- und Sedimentproben des Kivusees wurden einige der alten Vorstellungen zu einem neuen Modell weiterentwickelt. Danach ist das Methan hauptsächlich bakteriell aus dem organischen Kohlenstoff des Sediments entstanden. Wahrscheinlich enthält es auch geringe Beimengungen thermokatalytischen Methans.Der organische Kohlenstoff des oberen Sediments stammt zu rd. 70% aus dem vorwiegend magmatischen Kohlendioxid (alter Kohlenstoff), das aus dem Tiefenwasser durch turbulenten Austausch in die Biozone des Sees gelangt und dort assimiliert wird. Die restlichen 30% stammen aus dem in der Biozone assimilierten atmosphärischen Kohlendioxid (junger Kohlenstoff). Weil jedoch auch Methan aus tieferen Sedimentschichten in den See wandert, beträgt der¹⁴C-Gehalt des im Seewasser gelösten Methans nicht 30% modern, sondern nur ca. 10% modern.Weitere Isotopenuntersuchungen an Plankton-, Methan-, Kohlendioxid- und Sedimentproben sind notwendig, um das Modell abzusichern.

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Résumé De grandes quantités de méthane et d'oxyde carbonique sont dissoutes dans les eaux profondes du Lac Kicu. Alors qu'on est en général d'accord sur l'origine surtout magmatique de l'oxyde carbonique, les modèles devant représenter la genése du méthane sont contradictoires. Ils reposent sur des données trop peu nombreuses et en partie trop inexactes.A l'aide de nouveaux résultats de mesures faites sur des échantillons de gaz et du sédiment, on a développé un nouveau modèle, à partir des anciennes représentations. D'après celui-ci, le méthane provient pour sa plus grande part du carbone organique du sédiment, transformé par des bactéries. Il contient probablement des traces d'un méthane de thermocatalyse.Le carbone organique du sédiment supérieur provient pour 70% de l'oxyde carbonique surtout magmatique (carbone »ancien«), des eaux profondes parvenu, par échanges turbulents, dans la biozone du lac, où l'oxyde carbonique est assimilé. Les 30% restant proviennent de l'oxyde carbonique atmosphérique (carbone »jeune«) assimilé dans la biozone. Le méthane des couches profondes du sédiment migrant dans le lac, la teneur en¹⁴C de méthane dissous dans les eaux du lac n'est pas de 30% modernes, mais de 10% modernes.D'autres recherches sur les isotopes d'échantillons du plancton, du méthane, de l'oxyde carbonique et du sédiment du Lac Kivu seront nécessaires pour confirmer ce modéle.

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. , , . , , . . , . 70 % ( ), , . 30% (). , , ¹⁴ 30% modern, 10 % modern. , , .

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Experimente zur Zeolithbildung durch hydrothermale Umwandlung   总被引：1，自引：0，他引：1  

Helmut Höller  Ulrike Wirsching  Mahmud Fakhuri 《Contributions to Mineralogy and Petrology》1974,46(1):49-60

The formation of zeolites by hydrothermal alteration has been investigated by taking trass from the Laach volcanic area as a sample. Zeolites to be found are chabazite, phillipsite and analcime, all of which originated from the same phonolitic glass. This paper aims at explaining the formation of zeolites by means of experimental alteration of the pumice with various solutions. NaOH and KOH solutions were used in the experiments, these limited the formation conditions of chabazite, phillipsite, analcime in alkaline environments. Moreover, experiments were carried out with H₂O dist and with solutions that formed during the alteration of pumice by reacting with H₂O. These experiments were conducted to supply clues concerning the formation of zeolites in the Laach volcanic area. With NaOH solutions zeolites were formed from pumice within a temperature range of 70 to 250° C and a concentration range of 0.001 to 1.0 n; with KOH solutions they were formed in the same concentration range within a temperature range of 100 to 250° C. The formation of zeolites proved to depend much on temperature and concentration: At low temperatures high concentrations are necessary, higher temperatures need lower concentrations. With NaOH solutions the zeolites are formed in the succession, chabazite, phillipsite, analcime at increasing temperatures and increasing concentrations. With KOH solutions the same succession is to be found with rising temperature. With rising concentration, however, this succession is changed at higher temperatures: Phillipsite appears in place of analcime at high temperatures and concentrations. By the alteration of pumice with H₂O, zeolites are formed from 200° C onward. With solutions that had been formed during the alteration of pumice by reacting with H₂O, the minimum temperature for the formation of zeolites was 180° C. Concerning the genesis of zeolites in the Laach volcanic area, the experiments showed that the temperature for the formation of analcime was about 250° C; for the formation of chabazite and phillipsite it was between 150 and 190° C. The pH of the reacting solutions may have been between 7 and 8. Thus the experiments proved that from the same material different zeolites, chabazite, phillipsite, analcime may be formed by temperature change of the reacting solutions (H₂O to slightly alkaline solutions).  相似文献   

Modification of air flow over an escarpment — Results from the Hjardemål experiment     

Stefan Emeis  Helmut P. Frank  Franz Fiedler 《Boundary-Layer Meteorology》1995,74(1-2):131-161

Mean flow, turbulence, and surface pressure measurements over an escarpment are presented. The speed-up in the mean wind field shows the known dependence on stratification. Cross-sections of the standard deviation of horizontal and vertical wind components and of the friction velocity are derived from the data and compare favorably with the numerical model of Zeman and Jensen (1987). The modification of turbulent power spectra at intermediate frequencies can be explained by rapid distortion theory. At very low frequencies, there is a quasi-stationary response to the disturbance. Except for speed-up and standard deviations of the wind components, which are also shown for downslope wind, all results in this paper refer to upslope winds.An analysis of the vertical momentum flux reveals that upstream of the escarpment, most of the flux is transported in sweeps of fast, sinking motion to the ground. Downstream of the escarpment, ejections of slow, rising motion dominate the turbulent transport.  相似文献