DYNAMIC RESPONSE OF EQUIPMENT IN STRUCTURES WITH SLIDING SUPPORT     

L. Y. LU  Y. B. YANG 《地震工程与结构动力学》1997,26(1):61-77

The dynamic behaviour of a single degree-of-freedom (DOF) equipment mounted on a sliding primary structures subjected to harmonic and earthquake ground motions is studied numerically. To deal with the discontinuity nature of sliding structural systems, in this work the fictitious spring model is adopted. With the problem formulated in a state space form, an incremental numerical scheme capable of dealing with multi-DOF sliding structural systems is proposed for solving the time history responses. Numerical examples excited by harmonic and real earthquake ground motions are considered in order to study the following three effects: (1)the variation of the frictional coefficient of the sliding support, (2)subharmonic resonance and (3)effect of tuning (i.e. when the frequency of the equipment is coincident with or close to the fundamental frequency of the primary structure) on the mounted equipment. The dynamic characteristics of the mounted equipment are highlighted in the analysis of the numerical examples. © 1997 by John Wiley & Sons, Ltd.  相似文献   

长江中游地区暴雨过程的500 hPa信号场特征     

陆慧娟  沈善普  黄嘉佑 《气象学报》2005,63(3):333-341

文中用500 hPa信号场研究了长江中游地区暴雨发生的气候异常环境,并提出用信号场合成图的检验方法来分析暴雨规律.结果表明,暴雨过程与无雨过程在500 hPa信号场中异常信号显著区的出现及分布形势有明显不同.分析14次暴雨过程的合成图,发现在发生暴雨过程第1天,正异常区常常出现在贝加尔湖附近地区(40°～50°N,80°～100°E)和中国华南地区(20°～25°N,100°～130°E),负异常区出现在中国长江中游北部地区.暴雨过程出现的主要特征是在110°E附近,形成南北向的"+-+"分布形势和波列.  相似文献   

川东某场镇后山滑坡发育特征与机理分析     

陈世龙  郭伟  陈亚婷  张涛  刘晓钦 《四川地质学报》2020,40(1):119-124

四川盆地红层丘陵地区局部垂向裂隙发育的坡体容易受强降雨影响发生平推式滑坡,对于该类滑坡前人已有较为系统的研究,但对该类滑坡体局部复活特征的研究尚不深入。以川东某地老平推式滑坡体上发育的现代滑坡为例,分析了这类老滑坡局部复活的机理特征,5·12强震对滑坡体完整性造成了一定程度的破坏,是老滑坡复活的因素之一;但后缘人工弃渣的加载是其复活最直接的激发因素。文章对治理方案进行了可行性探讨,最终选用"前缘抗滑桩+后缘截水沟+裂缝夯实"方案。  相似文献   

AN INVESTIGATION INTO THE BASE SLIDING RESPONSE OF RIGID CONCRETE GRAVITY DAMS TO DYNAMIC LOADING     

R. A. MIR  C. A. TAYLOR 《地震工程与结构动力学》1996,25(1):79-98

A series of dynamic slip tests on a concrete gravity dam model was conducted on a shaking table. The aim of the experiments was to investigate the dynamically induced sliding and overturning characteristics of a typical low height gravity dam monolith cracked at its base. Tests indicated that downstream sliding is the main instability that could be expected during an earthquake. Dynamic, finite element analyses of the experimental model, using a Lagrangian contact surface algorithm, were also performed. A comparison of the experimental and analytical responses indicated that the seismically induced slip can be predicted reasonably by such a contact surface algorithm implemented in a standard finite element package. A comparison of observed displacements with Newmark's sliding block displacements indicated that a conservative estimate of seismic induced slip of a gravity dam could be obtained by using Newmark's sliding block concept, generally adopted for earth dams and embankments.  相似文献   

SEISMIC RESPONSE OF SLIDING STRUCTURES TO BIDIRECTIONAL EARTHQUAKE EXCITATION     

R. S. JANGID 《地震工程与结构动力学》1996,25(11):1301-1306

Seismic response of a one-storey structure with sliding support to bidirectional (i.e. two horizontal components) earthquake ground motion is investigated. Frictional forces, which are mobilized at the sliding support, are assumed to have ideal Coulomb-friction characteristics. Coupling effects due to circular interaction between the frictional forces are incorporated in the governing equations of motion. Effects of bidirectional interaction of frictional forces on the response are investigated by comparing the response to two-component excitation with the corresponding response produced by the application of single-component excitations in each direction independently. It is observed that the response of the sliding structure is influenced significantly by the bidirectional interaction of frictional forces. Further, it is shown that the design sliding displacement may be underestimated if the bidirectional interaction of frictional forces is neglected and the sliding structures are designed merely on the basis of single-component excitation.  相似文献   

软着陆保护橡胶支座隔震体系振动台试验研究与比较     

杨林  闫维明  周锡元  常永平 《地震工程与工程振动》2006,26(3):210-214

本文对一基础隔震模型进行了软着陆保护振动台模拟地震动试验,展示了该隔震体系在发生水平向大变形条件下,在不同后备支座以及滑移面摩擦系数不同情况下,轴压力从承载支座向后备支座转移的情况。结果表明:软着陆隔震保护体系不仅保护了承载支座免遭大变形失稳破坏,同时还能提供摩擦阻尼,将隔震层位移和上部结构层间位移控制在允许范围内。文中对隔震层位移、上部结构最大层间位移及绝对加速度等进行了分析,所得理论曲线与试验拟合曲线吻合较好。具有很大的应用前景。  相似文献   

滇西一些新生代飞来峰的构造演化          下载免费PDF全文

王二七  王世锋  樊春  王刚 《地质科学》2006,41(1):170-180

在印度和欧亚大陆相互作用下,滇西三江造山带在新生代中期发生了强烈的东西向缩短,地壳物质的大规模推覆作用形成众多的飞来峰。野外调查发现:这些飞来峰中有的在就位后没有再发生过变形,如分布在兰坪——思茅盆地中段的无量山东北山麓一带的一系列上三叠统灰岩飞来峰;有的飞来峰在就位后再次遭受到强烈的变形,如分布在兰坪盆地金顶一带的上三叠统灰岩飞来峰,在渐新世时与下伏岩层一同卷入了强烈的褶皱变形;分布在大理地区鹤庆盆地西侧的中三叠统灰岩飞来峰因受到后期东西向伸展构造的破坏,已被改造成分选极差的重力滑塌沉积。这些古近纪飞来峰由于在就位后再次发生了变形,所以不应称之为飞来峰,应称为异地岩或者是外来岩块。  相似文献   

不同计算形式的相关分析在气象中的应用综述     

朱玉祥  江剑民  赵亮  刘海文  侯美亭  李宏毅  万文龙  赵翠光 《热带气象学报》2021,37(1):1-13

相关分析在气象科研和业务中具有广泛应用,是定量分析气象变量之间关系的重要工具.首先系统综述了气象科研与业务中不同计算形式的相关分析算法,然后重点阐述了相关分析在气象领域应用的最新进展,特别是全窗口滑动相关和相关系数的扫描式多尺度突变检测算法.接着介绍了大数据研究领域中新发展的相关分析算法,简析了其对气象相关分析的启示....  相似文献   

黄河口埕岛海域表层沉积物土性的区域变化及其机理分析     

张衍涛  常方强  孟祥梅  张建  贾永刚 《海洋科学进展》2009,27(3)

搜集汇总黄河口埕岛海域地质勘察资料,研究该区土性参数区域分布特征,包括分析海域内土体类别,绘制不同区域内地基承载力、标贯击数、粘粒含量、含水量、孔隙比和液塑限等值线图.研究发现,海域表层土体主要由粉土和粉质粘土组成,此外还有小面积的粉砂和淤泥质土,中部大面积地区为粉土,东南区域分布有粉质粘土和淤泥质土;地基承载力较高的区域主要分布在海域中部与西南部,海域的北部与东南部土体强度较低,并且含水量、孔隙比和液塑限也较大,土性区域变化与水深变化特性较为一致.最后分析土性区域变化机理认为,极端海况下该区土体发生液化剪切破坏,沿斜坡滑移运动一定距离后再次沉积可形成这种现象.  相似文献   

剪切作用下Cu(100)扭转晶界塑性行为研究   总被引：1，自引：0，他引：1       下载免费PDF全文

赵雪川  刘小明  高原  庄茁 《海洋学报》2010,32(9):6362-6368

本文采用分子动力学方法研究了在剪切载荷作用下,Cu(100)扭转晶界对Cu柱屈服强度的影响.模拟结果发现,在加载过程中,低角度扭转晶界形成的位错网发生位错形核与扩展,位错之间的塞积作用提高了Cu柱的屈服强度;对于高角度扭转晶界,晶界发生滑动降低了Cu柱的屈服强度.同时发现,随着扭转角度的增加,Cu柱的屈服强度先增大,当扭转角度大于临界角度时,Cu柱的屈服应力逐渐减小.这表明剪切载荷作用下,两种不同的机理主导Cu柱的屈服,对于小于临界角度的扭转晶界,Cu柱的屈服由晶界位错形核和扩展机理主导,对于大于临界角度  相似文献