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81.
Seismic performance of exterior beam–column subassemblages of reinforced concrete structure designed and detailed on the basis of the provisions of Eurocode and Indian Standards at different stages of their evolution is evaluated. Performance of the subassemblages designed and detailed according to the three different stages of codal evolution (gravity load design, ‘Nonductile’, and ‘Ductile’) is evaluated through analytical formulations and experimental investigations. In the ‘NonDuctile’ specimens, it has been observed that the shear distortion and degradation in stiffness and strength are significantly high. Performance of the ‘Ductile’ specimens based on Eurocode and Indian Standards is almost similar in terms of strength and stiffness degradation. Nevertheless, the specimen designed on the basis of Indian Standard shows higher energy dissipation at a given drift ratio. In the analytical study, shear and flexural failure of members of subassemblage and shear failure of the joint are considered as possible modes of failure of the beam–column subassemblage. For evaluating the shear strength of the joint region, a soften strut‐and‐tie model is used. Analytically obtained strengths based on the failure criteria of different components of the specimens have been first validated with experimental results and then used to determine the strength of the specimens. The investigation could indicate even the mode of failure at local level. It is utmost important to mention here that even the ductile specimens dissipate most of the energy through the development of damage in the joint region, which is neither desirable nor safe for the stability of whole structure. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
82.
应用P波初动半周期直接测定环境剪应力值的方法,测定了北部湾6.1,6.2级地震前后中小地震的环境剪应力值τ0,由此分析了北部湾地震过程的环境应力场特征。结果表明,北部湾6.1级地震后平均剪应力值较高,达18MPa左右;6.2级地震及两次5级余震后剪应力值下降很快,降至目前的6MPa左右。在此基础上对北部湾地震活动趋势作了初步分析。 相似文献
83.
Pulsatory characteristics of wind velocity in sand flow over typical underlying surfaces 总被引:1,自引:0,他引:1
ZHANG KeCun QU JianJun ZU RuiPing & FANG HaiYan Key Laboratory of Desert Desertification Cold Arid Regions Environmental Engineering Research Institute Chinese Academy of Sciences Lanzhou China 《中国科学D辑(英文版)》2007,50(2):247-253
Pulsatory characteristics of wind velocity in sand flow over Gobi and mobile sand surface have been investigated experimentally in the wind tunnel. The primary goal of this paper is to reveal the relation- ship between pulsatory characteristics of instantaneous wind speed in sand flow and the motion state of sand grains. For a given underlying surface, pulsation of wind velocities in sand flow on different heights has a good correlation. As the space distance among different heights increases, fluctuation of instantaneous wind speed presents a decreasing trend and its amplitude is closely related to the mo- tion state of sand grains and their transport. Pulsatory intensity increases with the indicated wind speed, but its relative value does not depend on it, only agrees with height. 相似文献
84.
Filiz Bilgili Hans-Jürgen Götze Roman Pašteka Sabine Schmidt Ron Hackney 《International Journal of Earth Sciences》2009,98(3):571-583
An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence
or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong,
positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model”
against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer
anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic
inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes.
We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was
updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The
final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural
models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density,
intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed
investigations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
85.
以苏里格气田东部盒8段典型的致密砂岩气藏为例,运用核磁共振、恒速压汞、铸体薄片、物性、X-衍射等实验资料,探讨了影响可动流体赋存差异的微观地质 因素。结果表明,盒8段储层可动流体饱和度低,T2谱分布均为左高峰右低峰的双峰态;黏土矿物的充填与孔隙类型是孔隙结构复杂的重要因素,孔隙结构是影响可动流体赋存特征的关键;面孔率、喉道 半径、孔喉半径比是影响可动流体饱和度的主要因素,有效孔隙体积、分选系数对可动流体饱和度影响明显,储层物性、黏土矿物、有效喉道体积、孔隙半径对可动流体饱和度影响较弱。 相似文献
86.
This paper presents relative secular variations of the total intensity of the geomagnetic field against a background of results of magnetic anomaly interpretation along seismic profile P4. Profile P4 crosses a Variscan folding zone in the Paleozoic Platform (PLZ), the Trans-European Suture Zone (TESZ), and the Polish part of the East European Craton (EEC). Secular geomagnetic field variations
measured in 1966–2000 along a line adjacent to seismic profile P4 were analysed. The study of secular variations, reduced to the base recordings at the Belsk Magnetic Observatory, showed that the growth of geomagnetic field at the East European Craton was slower than in the Trans-European Suture Zone and the Paleozoic Platform.A 2D crustal magnetic model was interpreted as a result of magnetic modelling, in which seismic, geological and geothermal data were also used. The modelling showed that there were significant differences in the magnetic model for geotectonic units, which had been earlier determined based on deep seismic survey data. It should be noted that a fundamental change of trend of the relative secular variations was observed at the slope of the Precambrian Platform. After analysing the geomagnetic field observed along profile P4, the hypothesis that the contact between Phanerozoic and Precambrian Europe lies in Poland's territory can be proven. 相似文献
87.
Tidal currents,energy flux and bottom boundary layer thickness in the Clyde Sea and North Channel of the Irish Sea 总被引:2,自引:0,他引:2
A. M.?DaviesEmail author P.?Hall M. J.?Howarth P. J.?Knight R. J.?Player 《Ocean Dynamics》2004,54(2):108-125
A high-resolution three-dimensional model of the Clyde Sea and the adjacent North Channel of the Irish Sea is used to compute the major diurnal and semidiurnal tides in the region, the associated energy fluxes and thickness of the bottom boundary layer. Initially, the accuracy of the model is assessed by performing a detailed comparison of computed tidal elevations and currents in the region, against an extensive database that exists for the M2, S2, N2, K1 and O1 tides. Subsequently, the model is used to compute the tidal energy flux vectors in the region. These show that the major energy flux is confined to the North Channel region, with little energy flux into the Clyde Sea. Comparison with the observed energy flux in the North Channel shows that its across-channel distribution and its magnitude are particularly sensitive to the phase difference between elevation and current. Consequently, small changes in the computed values of these parameters due to slight changes of the order of the uncertainty in the open-boundary values to the model, can significantly influence the computed energy flux. The thickness of the bottom boundary layer in the region is computed using a number of formulations. Depending upon the definition adopted, the empirical coefficient C used to determine its thickness varies over the range 0.1 to 0.3, in good agreement with values found in the literature. In the North Channel, the boundary layer thickness occupies the whole water depth, and hence tidal turbulence produced at the sea bed keeps the region well mixed. In the Clyde Sea, the boundary layer thickness is a small fraction of the depth, and hence the region stratifies.Responsible Editor: Phil Dyke 相似文献
88.
为了得到与实测数据更为一致的散射模型,对KHCC03散射模型进行了改进.研究了考虑波浪破碎影响的KHCC03散射模型的适用范围.研究结果表明,KHCC03散射模型在入射角为25°~40°范围内,模型结果与实测数据吻合较好,在入射角小于25°和入射角大于40°的情况下,模型结果与实测数据差异较大.针对这一问题,对KHCC03模型进行了改进,结果表明:与原KHCC03模型相比,改进后的模型结果与实测数据吻合程度明显提高. 相似文献
89.
90.