Assessment of Effects of Reductions of Lateral Stiffness along Height on Buildings Modeled as Elastic Cantilever Shear Beams

A simplified model useful for assessing economic losses due to moderate seismicity events in urban areas has been developed by studying the behavior of buildings before yielding their structural system, allowing for nonuniform stiffness along their height. In particular, buildings are modeled as cantilever shear beams with uniform mass and parabolic reduction of lateral stiffness. This particular stiffness distribution is relevant, as it could be expected to occur in buildings where earthquake action is a critical structural design criterion. The equation of motion governing the dynamic behavior of the proposed model is solved analytically, finding mode shapes in terms of first and second zero-order Legendre functions. The solution is verified by comparing it with results obtained from fine mesh finite element models. The effect of reducing the lateral stiffness is then studied in the first five modes of vibration. Results include modal periods, mode shapes, modal participation factors, and derivatives of mode shapes. In general, it is found that effects of reduction of lateral stiffness in mode shapes are moderate when the lateral stiffness in the free end is smaller than about seventy percent of the lateral stiffness at the fixed end, but become significant for larger reductions. Effects are particularly important for the derivative of the mode shapes, which could play a significant role in estimating interstory drift demands in buildings. Model usefulness is showcased by analyzing a test case where both acceleration and drift demands are assessed by considering uniform beams and beams with parabolic stiffness variation, finding notable improvements by considering the latter.     

《春秋·庄公三十二年》伐邢之"狄"考

《春秋》所载伐邢之"狄"应为商人.在邢国墓葬考古中,发现有"毁墓"现象,由年代和情势判断,只能是对邢有"亡国"之恨的商人所为.狄也叫戎.戎在金文中写作" ",最初是商王小乙之子"子 "的氏族徽志.这个氏族一部分居于王畿北境,今河北新乐一带,负守土之责.周公东征后逃匿太行山中.狄也作翟.翟,《说文》云"山雉尾长者",《赵世家》云"子姓".图腾和族姓皆与商人相同.     

Performance of Degrading Reinforced Concrete Frame Systems Under the Tohoku and Christchurch Earthquake Sequences

Field investigations after the recent Tohoku and Christchurch earthquakes reported failure of structural systems due to multiple earthquakes. In most failure cases the reported damage was mainly due to dramatic loss of stiffness and strength of structural elements as a result of material deterioration due to repeated earthquake loading. This study aims to investigate the degrading behavior of reinforced concrete frame systems subjected to Tohoku and Christchurch earthquake sequences. Numerical models of RC frames that incorporate damage features are established and inelastic response history analyses are conducted. The results presented in this study indicate that multiple earthquake effects are significant.     

论张家山汉简《盖庐》

张家山汉简《盖庐》篇,不仅使我们看到已佚《伍子胥》一书的原貌,而且对研究吴越的学术思想,提供了崭新的资料。     

基于腾讯迁徙数据的中国“春运”城市间人口流动空间格局

“腾讯迁徙”大数据基于位置服务，实时、动态、完整、系统地描述了用户日常出行活动的轨迹。通过采集“腾讯迁徙”数据平台中2018年春运期间中国346个地级及以上城市之间的逐日人口流动数据，分“节前、节中、节后”3个时间段，利用复杂网络分析方法，从人口流动的集散层级、集散体系分层集聚特征、人口流动空间格局、网络空间特征等角度分析各时间段城市间的人口流动特征与空间格局。结果表明，腾讯迁徙大数据直观地揭示了春运期间中国城市间人口流动空间格局，3个时段人口的净流入均呈现十字形骨架支撑的菱形分布，人流集散中心主要集中在京津冀、长三角、珠三角和成渝4大城市群，与城市等级有较强的一致性。人口流动集散体系呈明显的分层集聚，城市行政级别的高低与人口流动影响力存在一定的正相关关系，大部分城市人口流动处于“相对平衡”状态。人口流动网络呈现东密西疏的分布特征和东部并联、西部串联的网络关联特征。人口流动网络局部具有较明显的“社区”结构特征，聚为3个大区级、5个跨区域级和1个地区级社区。     

秦子姬簋盖初探

珍秦斋藏秦子姬簋盖是新发现的春秋早期秦铭文材料。本文解释了铭文词句,又根据《史记·秦本纪》的有关记载,并参考宝鸡太公庙出土秦武公及王姬钟铭文的研究,认为铭文中的“秦子”是指秦出子,“秦子姬”乃是其生母“鲁姬子”。这对于讨论青铜器铭文研究中的“秦子”问题以及秦国早期历史的探索,有一定的参考价值。     

湖北老河口杨营春秋遗址发掘简报

杨营春秋遗址位于湖北省老河口市南郊杨寨村一组,1994年10～12月,湖北省文物考古研究所和老河口市博物馆联合对该遗址进行了发掘,获得了一批重要的春秋时期的遗迹和遗物。主要遗迹有灰坑、水井等,遗物有陶、铜、铁、石器等,其中所出土的春秋晚期铁器,数量较多,品种较齐全,为研究我国特别是楚国铁器的出现和使用提供了极其重要的考古资料。     

新郑铁岭墓地M550发掘简报

铁岭墓地是郑韩故城西北方向一处面积巨大的邦墓地,2009年郑州市文物考古研究院在此发掘了14座铜器墓,多数配有车马坑,其中3座墓铜器得以保留。这些铜器,从器型及纹饰来看有演变关系,对认识铁岭墓地的年代跨度有重要意义。     

中国财税博物馆藏滕侯赇之歌钟考

2002年前后,中国财税博物馆征集入藏一套4件春秋晚期的编镈,其中一件钲部有清晰的滕侯赇之歌钟6字铭文,揭示了一个史料无载的滕国国君名,填补了滕国历史研究中的一个空白。这组青铜镈器形规整,铸造精良,但没有调音结构,可能是为滕侯赇下葬专门铸造的。     

Time‐bubbles of nationalism: dynamics of solidarity ritual in lived time

The growth of modern nationalism can be attributed to structural causes, especially the growth of the strong bureaucratic state that penetrates society, creating cultural uniformity and national identity. But structurally based nationalism need not be very intense, or constant; even when institutionalised in periodic formal rituals, it can be routine, low in emotion – even boring. We need to explain sudden upsurges in popular nationalism, but also their persistence and fading in medium‐length periods of time. Nationalist surges are connected with geopolitical rises and falls in the power‐prestige of states: strong and expanding states absorb smaller particularistic identities into a prestigious whole; weaker and defeated states suffer delegitimation of the dominant nationality and fragment in sudden upsurges of localising nationalities. Passing from macro‐patterns to micro‐sociological mechanisms, conflict producing solidarity is a key mechanism: dramatic events focus widespread attention and assemble crowds into spontaneous ‘natural rituals’ – mass‐participation interaction rituals, as distinct from formal rituals. Evidence from public assemblies and the display of national symbols following the terrorist attacks of 11 September 2001 (9/11) shows an intense period of three months, then gradual return to normal internal divisions by around six months. Spontaneous rituals of national solidarity are produced not only by external conflict but by internal uprisings, where an emotional upsurge of national identity is used to legitimate insurgent crowds and discredit regimes. Although participants experience momentary feelings of historic shifts, conflict‐mobilised national solidarity lives in a 3–6‐month time‐bubble, and needs to institutionalise its successes rapidly to have long‐term effects.