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排序方式: 共有3285条查询结果,搜索用时 15 毫秒
1.
固定式海洋平台利用TLD的减震研究 总被引:7,自引:0,他引:7
本文研究固定式海洋平台利用调谐液体阻尼器(TunedLiquidDamper,简称TLD)减小地震反应的方法。首先探讨了调谐频率比、激磁频率比对减震效果的影响,在此基础上建立了TLD——平台系统的力学模型和运动方程,通过数值计算验证了该方法的有效性 相似文献
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An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation. 相似文献
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This article documents the analytical study and feasibility of placing a tuned mass damper in the form of a limber rooftop moment frame atop relatively stiff structures to reduce seismic acceleration response. Six existing structures were analytically studied using a suite of time history and response spectra records. The analyses indicate that adding mass in conjunction with a limber frame results in an increase in the fundamental period of each structure. The fundamental period increase generally results in a decrease in seismic acceleration response for the same time history and response spectra records. Owing to the limber nature of the rooftop frames, non‐linear analysis methods were required to evaluate the stability of the rooftop tuned mass damper frame. The results indicate the addition of a rooftop tuned mass damper frame reduces the seismic acceleration response for most cases although acceleration response can increase if the rooftop frame is not tuned to accommodate the specific structure's dynamic behaviour and localized soil conditions. Appropriate design of the rooftop tuned mass damper frame can result in decreased seismic acceleration response. This translates to safer structures if used as a retrofit measure or a more economical design if used for new construction. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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地震模拟振动台振动对建筑物中人体的舒适感的影响分析 总被引:1,自引:0,他引:1
本文给出了一种地震模拟振劝台振运对建筑物中人体的舒适感影响的分析方法,并结合实例进行了具体分析。文中给出的分析方法和实例计算结果对于地震馆的设计有一定参考价值。 相似文献
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SMA-MR复合型阻尼器 总被引:5,自引:0,他引:5
利用形状记忆合金超弹性、形状记忆特性和MR液的材料特性,提出了SMA-MR复合阻尼器,建立了阻尼器的理论模型。通过输入正弦波得到小震、大震时相应的滞回曲线,并对一单层框架进行输入El Centro地震波下的减震效果分析,比较了SMA-MR阻尼器、仅有SMA和仅有MR作用下的减震效果。结果表明,所设计的SMA-MR阻尼器具有卓越的阻尼性能,对大震、小震的控制实现了自适应的智能性。 相似文献
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Field vibration mitigation by honeycomb WIB for pile foundations of a high-speed train viaduct 总被引:5,自引:0,他引:5
Environmental vibrations from recent high-speed trains are becoming a special concern in the civil and environmental engineering field since they can give detrimental effects to residents, sensitive equipments and high-tech production facilities in the vicinity of train tacks. Herein, aiming at the vibration mitigation for a specific high-tech industrial area, the low-frequency vibrations from a train viaduct are targeted over an anticipated range. A theoretically designed innovative countermeasure, called honeycomb wave impeding barrier (WIB) for a wave impeding barrier, is introduced and its effects are investigated by computer simulation. The present WIB is based on the wave dispersion phenomenon that can modulate the incoming wavelengths into the shorter wavelengths, creating an apparent wave cut-off characteristic in the wave field across WIB installation area. The shorter wavelengths are further impeded due to the impedance ratio of the WIB walls and in-fill materials and absorbed by the in-fills more. The three-dimensional FEM simulation demonstrates a dramatic reduction effect that is difficult to achieve by conventional measures. 相似文献
10.
Ali Kahriman 《Soil Dynamics and Earthquake Engineering》2004,24(11):887-892
The aim of this study is to predict peak particle velocity level at a limestone quarry located in Istanbul, Turkey. The ground vibration components were measured for 73 blast events during the bench blast optimization studies during a long period. In blasting operations; ANFO (blasting agent), gelatine dynamite (priming) and NONEL detonators (firing) were used as explosives at this site. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured by means of vibration monitors for every event. Then, the data pairs of scaled distance and particle velocity were analyzed. The equation of scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity. At the end of statistical evaluations, an empirical relationship with good correlation was established between peak particle velocity and scale distance for this site. The established relationship and the results of the study are presented. 相似文献