Inelastic buildings with tuned mass dampers under moderate ground motions from distant earthquakes

The effectiveness of tuned mass dampers (TMD) in vibration control of buildings was investigated under moderate ground shaking caused by long‐distance earthquakes with frequency contents resembling the 1985 Mexico City (SCT) or the 1995 Bangkok ground motion. The elastic–perfectly plastic material behaviour was assumed for the main structure, with linear TMDs employed by virtue of their simplicity and robustness. The accumulated hysteretic energy dissipation affected by TMD was examined, and the ratio of the hysteretic energy absorption in the structure with TMD to that without it is proposed to be used, in conjunction with the peak displacement ratio, as a supplementary TMD performance index since it gives an indication of the accumulated damage induced in the inelastic structures. For the ground motions considered, TMD would be effective in reducing the hysteretic energy absorption demand in the critical storeys for buildings in the 1.8–2.8 s range. The consequence is reduction in damage of the buildings which would otherwise suffer heavy damage in the absence of TMD, resulting in economical restorability in the damage control limit state. This is of practical significance in view of the current trend toward performance‐based design. Copyright © 2001 John Wiley & Sons, Ltd.     

Use of a shared tuned mass damper (STMD) to reduce vibration and pounding in adjacent structures

The dynamic response of tall civil structures due to earthquakes is very important to civil engineers. Structures exposed to earthquakes experience vibrations that are detrimental to their structural components. Structural pounding is an additional problem that occurs when buildings experience earthquake excitation. This phenomena occurs when adjacent structures collide from their out‐of‐phase vibrations. Many energy dissipation devices are presently being used to reduce the system response. Tuned mass dampers (TMD) are commonly used to improve the response of structures. The stiffness and damping properties of the TMD are designed to be a function of the natural frequency of the building to which it is connected. This research involves attaching adjacent structures with a shared tuned mass damper (STMD) to reduce both the structures vibration and probability of pounding. Because the STMD is connected to both buildings, the problem of tuning the STMD stiffness and damping parameters becomes an issue. A design procedure utilizing a performance function is used to obtain the STMD parameters to result in the best overall system response. Copyright © 2001 John Wiley & Sons, Ltd.     

Trace Elements Analysis of Geological Samples by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

ＩＮＴＲＯＤＵＣＴＩＯＮＬａｓｅｒａｂｌａｔｉｏｎｉｎｄｕｃｔｉｖｅｌｙｃｏｕｐｌｅｄｐｌａｓｍａｍａｓｓｓｐｅｃｔｒｏｍｅ ｔｒｙｉｓａｎｉｎｃｒｅａｓｉｎｇｌｙｄｅｖｅｌｏｐｅｄａｎａｌｙｔｉｃａｌｔｅｃｈｎｉｑｕｅｆｏｒｓｏｌｉｄｓａｍｐｌｅａｎａｌｙｓｉｓ.ＬＡ ＩＣＰ ＭＳｏｆｆｅｒｓａｔｔｒａｃｔｉｖｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｈｉｇｈｓｅｎｓｉｔｉｖｉｔｙ ,ｌｏｗｄｅｔｅｃｔｉｏｎｌｉｍｉｔｓ,ｍｉｎｉｍａｌｓａｍｐｌｅｐｒｅｐａｒａ ｔｉｏｎ ,ｌｅｓｓｏｘｉｄｅｓｉｎｔｅｒｆｅ…     

Research on Practicability and Feasibility for a New-Type Tuned Mass Damper System-TMD

lNTRODUCTIONThe theories and applications of structural contr()l tlcveloped rapidly in the last 20 years. As one of the additiona1 I)asslve control technologY' TMD is used in practice and can suppress the vibration caused by wind or machinery shake (Ayorinde and Warburton, 1980; Den Hartog, l956 ). The TMDsystem has been used in the industrial and civil buildlngs t() rc-duce structural vibration in some European and American ()o[lntries (Ayorinde and Warburton, l980; Warburton. ] f)…     

论大气模式的垂直离散(Ⅱ)──垂直离散

提出了用ｌｎσ等距分层和Ｔｓｃｈｅｂｙｓｃｈｅｆｆ多项式沿垂直方向展开气象要素的方案；并证明：在绝热无耗散且时间和水平方向要素连续的情况，可以在高精度条件下，保证质量和能量守恒，且具有正确的动、位能之间的转换关系。数值计算表明：两方案均有较高的计算精度；在积分静力方程时，位势高度计算误差显著小于ＥＣ７９方案。     

Qualitative and quantitative aspects of the evolution of the planktonic populations in Lake Lugano

This study is a summary of all available information on the long-term and on the more recent development of the planktonic populations in Lago di Lugano with regard to its trophic evolution. The first effects of the lake eutrophication became manifest beginning in the 1950's and brought to important changes in the planktonic community as the appearance and the rapid increase of the filamentous algaeOscillatoria rubescens andStephanodiscus hantzschii, and the disappearance of the zooplanktonic Diaptomidae. Since 1980 the phosphorus concentration began to decrease in lake's epilimnion and the planktonic community showed a new composition, evidencing the presence of others predominant species:Oscillatoria redekei, Lyngbya limnetica, Stephanodiscus sp. (little form). Since 1989 algal standing crop reduced its value below 2 g m^–2 (dry weight); furthermore a strong decrease of the Cyanophceae and the appearance of new predominant species (Tabellaria fenestrata, div. Ulotrichales) occurred. At the same time an increase of the herbivorous zooplankton (Daphnia hyalina) and the come-back of the Diaptomidae was observed. Only in the northern basin a decrease tendency of the primary production was observed, changing from 480 to about 300 g C m^–2 yr^–1 during the last 10 years.     

刘家坪杂岩体的岩石特征及时代

刘家坪杂岩体出露于扬子准地台西北边缘。该区扬子期岩浆活动,早期为刘家坪组海底喷发的中～酸性火山岩系,晚期先后侵入有角闪辉长岩—石英闪长岩—斜长花岗岩—辉绿岩脉。岩浆岩具有幔源岩浆及造山带地区火山岩的特征。据震旦系覆于刘家坪杂岩体之上,其底部砂砾岩的砾石中有杂岩体成分,以及杂岩体侵入于同位素年龄值为6.43亿年的刘家坪组之中,认为刘家坪杂岩体时代为前震旦纪。     

秦巴地区中——酸性浅成小岩体与金矿

本文叙述了秦岭大巴山地区中——酸性浅成——超浅成侵入——爆破“杂”岩体的地质特征及其分布;叙述了与岩体有成生联系的斑(玢)岩型、矽卡岩型、爆破(隐爆——坍塌)角砾岩型、构造蚀变岩型、热液脉型等类型金矿的地质特征;总结了岩体的成矿模式,同时指出了矿床类型和共(伴)生元素的成矿系列;指出分布在秦巴地区的5个印支期——燕山期岩体带中的21个小岩体群,其中数百个小岩体及其附近有找到多种类型金矿的可能,预测其找矿前景乐观,金矿资源潜力很大。     

北半球50条山地冰川近期的物质平衡状况

近期北半球大多数山地冰川的物质平衡为负,冰川普遍退缩,表明北半球气候暖化的趋势.由于区域气候波动和变化的差异性以及冰川对气候变化的敏感性(响应程度)的不同,北半球山地冰川在普遍退缩的背景下具有鲜明的区域特征.     

基于ArcGIS的滑坡空间分布的变维分形研究——以江西省宁都县为例

滑坡空间分布的定量研究对了解滑坡的发育特征具有实际意义，能够为滑坡的防治提供重要依据.为了了解滑坡的空间分布特征，以江西省宁都县1：5万地质灾害调查数据为基础，基于ArcGIS空间分析叠加模块，对滑坡空间分布规律应用变维分形理论进行定量研究，揭示出滑坡空间分布与地形地貌、岩土体类型、高程、坡度均呈二价累计和分形分布，使得滑坡与各因素之间的关系从定性分析上升到定量研究，并计算出分维值，说明了分维值的意义.