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Experimental study on the bidirectional inelastic deformation capacity of U‐shaped steel dampers for seismic isolated buildings 
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下载免费PDF全文 Diana Ene Shoichi Kishiki Satoshi Yamada Yu Jiao Yoshinao Konishi Masao Terashima Norihisa Kawamura 《地震工程与结构动力学》2016,45(2):173-192
Hysteretic dampers are used to dissipate earthquake‐induced energy in base‐isolated structures by acquiring inelastic deformations, rendering their hysteretic behavior of vital importance. The present paper focuses on investigating the behavior of U‐shaped steel dampers under bidirectional loading; this is significantly different from their corresponding uniaxial behavior. Two main sets of loading tests on full‐scale specimens are conducted in this regard: (i) quasi‐static tests with simple histories and (ii) dynamic tests with realistic loading histories. Based on the results obtained in the quasi‐static tests, an interaction curve that accounts for the reduction of the cyclic deformation capacity is proposed. However, the fidelity of this relation must be assessed under loading conditions similar to those of a seismically isolated structure subjected to an earthquake, which represents the goal of the second set of tests. The results of the dynamic tests validate the proposed interaction curve for estimating the deformation capacity of U‐shaped steel dampers under bidirectional loading. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Results of evolutionary calculations for a close binary system with a central helium burning He-star filling its Roche lobe and an accreting white dwarf are presented. Values for the mass of the components and the degree of central helium exhaustion before the filling of the Roche lobe are varied. It is shown that in such a system the mass accretion rate will remain for a long time (2–4) Ö 10–8
yr–1 ifq<1 (q=M
He,2/M
CO,1). The obtained results are discussed in connection with pre-supernova I phenomenon. 相似文献
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Enn Karro Ene Indermitte Astrid Saava Kadri Haamer Andres Marandi 《Environmental Geology》2006,50(3):389-396
A study was undertaken to examine the content and spatial distribution of fluoride in drinking water. Water samples (735) from public water systems covering all Estonian territory were analysed using SPADNS method. In order to specify the natural source of fluoride, the chemistry data from five aquifer systems utilised for water supply were included into the study. Fluoride concentrations in tap water, to a great extent, ranged from 0.01 to 6.95 mg/l. Drinking water in southern Estonia, where terrigenous Middle-Devonian aquifer system is exploited, has a fluoride concentration lower than recommended level (0.5 mg/l), thus promoting susceptibility to dental caries. The western part of the country is supplied by water with excess fluoride content (1.5–6.9 mg/l). Groundwater abstracted for drinking purposes originates from Ordovician and Silurian carbonate rocks. The content of fluoride in Silurian–Ordovician aquifer system is associated with the groundwater abstraction depth and the main controlling factors of dissolved fluoride are the pH value and the chemical type of water. 相似文献
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Geo-engineering tests that include Atterberg limits, linear shrinkage, compaction, California bearing ratio and strength tests
were used to assess the potential of raw-meal to modify Nigerian coal-reject. The results of the tests indicate that the liquid
limit, plastic limit and plasticity index as well as linear shrinkage values decreased with increasing raw meal content. The
results also show that the maximum dry density decreased as raw meal content increased up to a maximum of 6% for the modified
AASHTO and West African Standard (WAS) compaction energies and 2% raw meal content for BS compaction energy. The California
bearing ratio attained optimal value at 2% for the modified AASHTO and West African Standard (WAS) compaction energies and
6% raw meal content for BS compaction energy. Peak shear strength was also achieved at 6% raw meal content. These results
demonstrate that the geotechnical properties of the coal-reject can be improved significantly with the addition of up to 6%
raw meal when compacted at BS compaction energy and 2% raw meal content when compacted at modified AASHTO and WAS compaction
energies. 相似文献
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Analyses of hydrochemistry, modes of occurrence and dynamic dispersion of brine discharges were used to assess the economic potentials, environmental and geotechnical problems of saline water discharges in the Abakaliki Basin. Total salt concentration, energy input requirement and the nature of containment structures are important considerations in selection of appropriate and sustainable sourcing and processing system. Solute dispersion patterns from the brine discharges are controlled by the semi-regional hydrodynamic regime that is defined by the shallow, unconfined, fractured aquifer system. The ionic solute invasion from brines not only contribute to marginal wetland degradation, ground and surface water contamination but also predicate low performance and failures in water abstraction and supply systems through encrustation and corrosion. Brine harvest for industrial and domestic applications appears to be a major remedy to inhibit the environmental and geotechnical impacts of the brine discharges. 相似文献
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Ebenebe sand deposits from the designated Imo Formation (southeastern Nigeria) were evaluated using geologic, geochemical, and geotechnical techniques to ascertain the suitability for use as fine aggregate and industrial material. Results show that this formation consists of mainly quartz that show predominance of angular to subrounded sphericity, oblate to equant mineral shapes, while elongate and platy shaped grains are rare. It exhibits poorly sorted and well-graded particles that range from fine to coarse sand-sized grains. Of all the specimens taken from this geological deposit, geochemistry is dominated by a very high percentage of SiO2 (>?96%). The concentrations of Al2O3 and Fe2O3 vary from 0.58 to 2.2% and 0.09 to 0.89%, respectively. Sands show insignificant activity on soaking with water and caustic soda which demonstrate the paucity of deleterious minerals and organics. The properties of the sand deposits are evaluated based on the depositional and geomorphological environment and processes. The properties of the Ebenebe sand deposits were compared with the characteristics of other sand deposits having proven service performance and those specified by some referenced standards which implies that the studied sands possess a high potential for use as aggregate as well as industrial material, with some beneficiation. 相似文献
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Daniel Marcos Bonotto Ene Glria da Silveira 《Journal of South American Earth Sciences》2003,15(8):911-923
Samples of water, suspended solids, and bottom sediments from the Madeira River, Rondônia state, Brazil, were physically and chemically analyzed to investigate the actual Hg mobilization in the aquatic environment and compare it with that of other heavy metals and elements in the area. Two dimensionless Hg preference ratios were defined, expressing (1) the ratio of Hg and other elements in the liquid phase divided by the ratio of Hg and other elements in bottom sediments (Pl.phase) and (2) the ratio of Hg and other elements in the particulate matter divided by the ratio of Hg and other elements in bottom sediments (Ps.solids). These preference ratios are useful for comparing Hg transport in three different phases (liquid, particulate matter, and bottom sediments). They also were applicable to any analyzed element in the area studied, because they generated an almost constant value when the maximum calculated was divided by the minimum (Pl.phase=2931; Ps.solids=84) and because of their sensitivity to the dominance of sorption processes by Fe oxides and hydroxides. Mercury could be transported preferentially to other analyzed elements in the particulate phase only if its concentration reached values at least 104-fold higher than those expected or quantified in the area. 相似文献