共查询到19条相似文献，搜索用时 109 毫秒
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为研究复合材料电气设备抗震性能与减震技术应用效果，对特高压复合支柱材料绝缘子进行了抗震与减震地震模拟振动台试验，研究了设备动力特性和地震响应。白噪声试验结果表明:该复合材料支柱绝缘子在安装减震器后第1阶频率由1.11 Hz降低到1.04 Hz，表明减震器对设备结构的整体刚度影响较小。3种地震波试验结果表明:设备地震响应与地震动峰值加速度在抗震试验中呈线性变化关系，但在减震试验的应力响应中呈非线性变化关系；设备安装减震器后，试验地震动峰值加速度越大，减震效率越高，最高达到了66.32%；而位移减震率与地震动峰值加速度无明显规律，最大位移减震率为49.36%。试验研究结果表明:试验设备安装减震器后抗震性能得到显著提升，为复合材料电气设备抗震性能研究与减震技术应用提供了参考依据。 相似文献
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主要研究地面运动的频率成分在非弹性需求下对单自由度（SDF）和多自由度（MDF）钢架结构的作用。通过对文献进行详细的审查,识别出最能代表地面运动频率成分的指标。选择地面运动的平均周期（Tm）是由于它能区别各种不同地面运动的频谱形态及其与震级、距离和场地特征的关系。首先使用一组128次地面运动的记录根据L对单自由度体系在特定延性水平时的非弹性位移要求进行研究。然后通过采用相同的地面运动资料做增量动力分析,把研究扩展到多自由度系统,评价Tm对各种工程需求参数的影响。得到的结果表明,对于单自由度体系,当弹性周期（Te）与Tm的比值低于1时,位移将增大。对于多自由度体系,结果证明了高阶振型对于基底剪力的影响和当Tm接近结构的高阶振型周期时,对最大层间侧移的影响变得更加显著。对单自由度体系和多自由度体系,在非弹性水平较高时这些观测更为明显。研究结果对于欧洲抗震设计法是尤为重要的。 相似文献
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剪切型结构的抗震强度折减系数研究 总被引：1，自引：0，他引：1
为了研究剪切型结构抗震强度需求的变化规律,本文基于单自由度体系的非线性时程分析,研究了不同场地条件下延性折减系数与位移延性系数和结构自振周期的关系;采用修正等效单自由度体系位移延性折减系数的方法,研究了剪切型多自由度体系的延性折减系数;以基于中国建筑抗震规范设计的代表不同抗震能力要求的RC框架结构为分析对象,通过静力弹塑性分析,研究了RC框架结构的体系超强能力。分析结果表明场地类别、位移延性水准和结构振动周期对单自由度体系的延性折减系数有显著的影响;多自由度体系的抗震延性折减系数明显比其相应的等效单自由度体系的抗震延性折减系数小;RC框架结构的超强系数一般随结构楼层数的增加而减小,随抗震设防烈度的增大而减小,内框架的超强系数比边框架的超强系数大。 相似文献
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通过典型高压断路器的振动台实验及有限元模型计算, 分析了铅合金减震器的减震效果. 实验分析结果表明, 铅合金减震器不仅降低了断路器的加速度反应和应变反应, 而且没有增加断路器的位移反应. 其最大应变降低量平均达到30％, 且输入地震动越强, 减震效果越明显. 有限元模型计算分析进一步论证了铅合金减震器的减震效果, 尤其是具有丰富长周期地震动和速度脉冲地震动作用下的减震效果. 基于断路器的地震破坏模式, 本文将减震器的减震效果定义为断路器瓷柱最大应变的降低率. 综合计算结果和振动台试验结果, 本文初步确定了铅合金减震器的适用范围. 相似文献
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对基于位移的抗震设计方法单自由度体系弹塑性位移计算的等效线性化方法中的等效阻尼模型进行研究.在统计分析的基础上,提出了考虑场地类别和设计地震分组的等效阻尼比公式,并与不同阻尼比公式进行了比较.对不同等效线性化方法的计算误差进行了统计分析,结果表明,本文建议的公式在预测单自由度体系位移反应方面与动力弹塑性分析结果在统计意义上吻合得最好. 相似文献
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瓷柱式SF6高压断路器抗震性能分析 总被引：2，自引：1，他引：1
开展断路器的抗震性能分析,研究铅合金减震器的减震效果,对提高电气设备的抗震能力有重要意义。利用ANSYS,建立了LW36-252/T3150-40型瓷柱式SF6断路器的有限元模型。并以IEEE Standard 693推荐时程和汶川地震典型时程作为地震输入,分别计算了支架底部未安装与安装铅合金减震器时断路器的地震反应。分析了减震器的减震效果,对断路器的抗震性能作了评定。铅合金减震器有良好的减震效果,能有效提高设备的抗震能力,此断路器可达到IEEE Std 693-2005中等水准抗震水平。 相似文献
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动力基础系统非线性本构关系的研究 总被引：1，自引：1，他引：0
采用理想集总参数计算体系,以三次幂多项式模型反映动力地基的非线性特性,将非线性幂函数作为循环荷载作用下系统位移-力关系的主干骨线,在此基础上按照Masing二倍法则,将骨线拓展为位移一力的滞回曲线,建立了动力基础双曲线滞回动力学模型。提出了非线性广义刚度函数的概念,建立了动力基础系统在不同振动形式下的非线性本构关系。 相似文献
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在双向非线性隔震支座本构关系模型基础上,建立了单质点隔震体系在双向地震作用下的动力方程和计算方法。在8度、8.5度和9度罕遇地震作用下计算分析了隔震体系在各种动力参数下的地震反应,提出了在不同设防烈度下满足位移限制要求的合理纯铅屈重比,为隔震房屋设计提供了可靠的依据和途径。 相似文献
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国内外研究者已对非弹性单一塑性铰单自由度体系的R-μ-T关系获得了趋势一致的研究结论,但对工程中大量应用的多自由度体系R-μ关系的研究工作尚处于起步阶段。本文在确认多自由度体系与单铰单自由度体系非弹性反应特征差别的基础上,通过非弹性动力反应分析考察了多自由度钢筋混凝土框架结构的R-μ关系及其有效性;通过单铰单自由度体系与多铰单自由度体系及多自由度体系非弹性动力反应的对比,指出后两种体系在相同水准地震作用下的延性需求比单铰单自由度体系偏大。 相似文献
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Zoran T. Rakicevic Aleksandra Bogdanovic Dimitar Jurukovski Peter Nawrotzki 《Bulletin of Earthquake Engineering》2012,10(3):1049-1073
A shaking table testing of a 16.6 t five storey steel frame structure with and tuned mass damper (TMD) named as Tuned Mass Control System (TMCS) installed at the top has been carried out in the Dynamic Testing Laboratory at the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) in Skopje, Republic of Macedonia. For estimation of the effectiveness of Tuned Mass Control System (TMCS) large number of shaking table experiments have been performed. Simulating different earthquake time histories on the model structure with and without TMCS it has been demonstrated that this system is capable to reduce the responses in order from 10% to more than 50% depending on the frequency content of the seismic input and the corresponding sensitivity of the structure. Given a high quality analytical model of a structure and a dynamic absorber, a series of variant analyses have been performed within the study to investigate the effect of the individual parameters and evaluate the efficiency of the dynamic absorber. The analyses have been performed to define the effect of the location of the absorber, also, upon the dynamic behaviour of the structure in the case the absorber is installed at the different level (storey) of the structure. Comparative analysis of the structure with TMCS having optimally tuned its mechanical properties versus structure that has TMCS having the same mechanical properties as tested specimen showed that the TMCS additionally improves the structural behaviour, depending on frequency content of earthquake excitation. 相似文献
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形状记忆合金橡胶对高架桥梁碰撞减震效果的试验研究 总被引：2，自引：0，他引：2
地震作用下,高架桥梁相邻主梁间的碰撞会引起结构位移和加速度响应增大、应力提高,导致混凝土开裂、脱落和伸缩缝被挤压破坏,甚至引发桥梁落梁和倒塌等,因此采取减轻或者避免桥梁结构在地震作用下碰撞的措施显得尤为必要。设计制备了具有变形自恢复能力的形状记忆合金橡胶碰撞缓冲器,通过桥梁地震碰撞的振动台试验,研究了形状记忆合金橡胶缓冲器对桥梁碰撞的控制效果,提出了碰撞缓冲器吸能效率和结构自身耗能控制率指标。研究表明,形状记忆合金橡胶碰撞缓冲器具有稳定的吸能效率,能够大幅度降低桥梁结构碰撞加速度和碰撞力,这对于提高城市交通网络的地震安全性能具有重要意义。 相似文献
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It is pointed out that the number of modes which should be included in a mode superposition dynamic response analysis depends on both the frequency content and the distribution of the loading. If the loading frequency is low the effect of the higher modes can be approximated by a static analysis. A technique is described for calculating this static contribution from the higher modes; the total response is then represented by the sum of the lower mode dynamic response and the higher mode static effects. The effectiveness of the procedure is demonstrated by a numerical example. 相似文献
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本文提出了圆球减振装置对风力发电高塔振动控制的工作原理和计算方法,并对其控制效果进行了理论研究。首先利用拉格朗日方程推导得到圆球减振装置的自振频率及其对单自由度系统的被动控制力,并推广至多自由度系统。进而将风力发电高塔等效为集中质点模型,建立了风塔-减振装置体系的运动微分方程。用谐波叠加法模拟得到脉动风速时程,分析比较了风力发电高塔在无控及有控状态下的动力响应及疲劳寿命。计算结果表明,圆球减振装置是一种简单、经济和实用的减振装置,能够有效减小风塔的动力响应,延长其疲劳寿命。 相似文献
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Jimmy Lee 《地震工程与结构动力学》1990,19(8):1209-1218
Optimal mass ratios that minimize the response of a laminated beam with an attached absorber are tabulated for various values of beam damping. The beam is treated as an equivalent one degree of freedom (1DOF) main system vibrating in the fundamental mode. The beam is subjected to Gaussian white noise force and Gaussian white noise base frame acceleration. Optimal absorber frequency ratios and absorber damping ratios have been tabulated by others; the results for the classical 1DOF main system with attached absorber suggest that the optimized non-dimensional response decreases monotonically as the mass ratio increases. However, to generalize this monotonic relation may lead to inappropriate conclusions. If we define a constraint such that an increase in absorber mass leads to a proportional decrease in available beam construction material, i.e. effectively the combined mass of the beam and absorber is minimized, then variations in the mass ratio will affect the beam's parameters such as mass, stiffness and damping. Since some of these parameters are used for non-dimensionalising the response, inspection of non-dimensional responses may in some cases lead to inappropriate conclusions. This paper shows the optimal mass ratios for minimizing the response of a structure exposed to earthquake or fluid flow type random excitations. 相似文献
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The main intention of the present study is to reduce wind, wave, and seismic induced vibrations of jackettype offshore wind turbines (JOWTs) through a newly developed vibration absorber, called tuned liquid column gas damper (TLCGD). Using a Simulink-based model, an analytical model is developed to simulate global behavior of JOWTs under different dynamic excitations. The study is followed by a parametric study to explore efficiency of the TLCGD in terms of nacelle acceleration reduction under wind, wave, and earthquake loads. Study results indicate that optimum frequency of the TLCGD is rather insensitive to excitation type. In addition, while the gain in vibration control from TLCGDs with higher mass ratios is generally more pronounced, heavy TLCGDs are more sensitive to their tuned frequency such that ill-regulated TLCGD with high mass ratio can lead to destructive results. It is revealed that a well regulated TLCGD has noticeable contribution to the dynamic response of the JOWT under any excitation. 相似文献
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An investigation on the ground motion parameters and seismic response of underground structures 
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下载免费PDF全文 Peak ground acceleration (PGA), frequency content and time duration are three fundamental parameters of seismic loading. This study focuses on the seismic load frequency and its effect on the underground structures. Eight accelerograms regarding different occurred earthquakes that are scaled to an identical PGA and variation of ground motion parameters with ratio of peak ground velocity (PGV) to PGA, as a parameter related to the load frequency, are considered. Then, concrete lining response of a circular tunnel under various seismic conditions is evaluated analytically. In the next, seismic response of underground structure is assessed numerically using two different time histories. Finally, effects of incident load frequency and frequency ratio on the dynamic damping of geotechnical materials are discussed. Result of analyses show that specific energy of seismic loading with identical PGA is related to the seismic load frequency. Furthermore, incident load frequency and natural frequency of a system have influence on the wave attenuation and dynamic damping of the system. 相似文献
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Frozen soil plays an important role on the stability of railway and highway subgrade in cold regions. However, the dynamic properties of frozen soil subjected to the freeze–thaw cycles have rarely been investigated. In this study, cryogenic cyclic triaxial tests were conducted on frozen compacted sand from Nehe, Heilongjiang Province in China which was subjected to the closed-system freeze–thaw cycles. A modified Hardin hyperbolic model was suggested to describe the backbone curves. Then, dynamic shear modulus and damping ratio versus cyclic shear strain were analyzed under the different freeze–thaw cycles, temperatures, initial water contents, loading frequencies and confining pressures. The results indicate that the freeze–thaw process plays a significant effect on the dynamic shear modulus and damping ratio, which slightly change after one freeze–thaw cycle. Dynamic shear modulus increases with increasing initial water content, temperature, loading frequency and confining pressure. Damping ratio increases with increasing initial water content, while decreases with increasing temperature and loading frequency. The effect of confining pressure on the damping ratio was found not significant. Furthermore, the empirical expressions were formulated to estimate dynamic shear modulus and damping ratio of the frozen compacted sand. The results provide guidelines for evaluating the infrastructures in cold regions. 相似文献