核心筒领先层数对超高层结构竖向变形影响的分析

针对超高层建筑在施工过程中两种不同材料产生的竖向变形累计带给结构附加应力这一问题,对结构进行施工模拟是很有必要的.本文通过有限元分析软件Midas gen将结构划分为22个施工阶段,利用子结构状态叠加法对施工过程进行了精确模拟.结合本结构受力特点,在模拟过程中综合考虑了材料特性、边界条件及施工荷载等因素,分析了核心筒不同领先层数对超高层结构竖向变形、两者竖向变形差及外框架柱内力分布产生的影响.结果表明：混凝土的收缩徐变约占结构总变形的40%.因此,混凝土收缩徐变效应产生的影响不可忽略.通过模拟可知,核心筒领先不同层数会对结构竖向变形和内力产生较大影响,同时得出核心筒领先外框架6层时,两者的竖向变形差最小,其值为23.48 mm.通过施工模拟得出最佳领先层数,有效减小核心筒与外框架之间的竖向变形差,从而减小附加应力,为类似工程提供一定施工技术参考.     

竖向变形差异对高层结构的影响

高层结构在竖向荷载作用下,产生框架柱与剪力墙的弹性竖向变形差以及由变形差引起的结构附加内力.通过实例计算表明框架承担的内力有所增大,剪力墙承担的内力减小.框架梁顶部在墙一端负弯矩大、柱一端负弯矩小,同时提出减少竖向差异的措施.     

具有不同节点刚度的装配式框架结构在不均匀沉降下的内力响应分析

装配式框架结构与现浇式框架结构相比,梁柱连接节点较为薄弱,对不均匀沉降引起的附加应力更加敏感;由于装配式框架结构的施工方法不同,导致其梁柱节点连接刚度不同,故在不均匀沉降下进行节点连接刚度对装配式框架结构的稳定性影响研究。按照装配式框架结构的层数和跨数,利用Midas Gen软件建立四种工况模型,将地表不均匀沉降以竖向位移的模式施加于装配式框架结构柱脚上,模拟和对比分析不同节点刚度的装配式框架结构内力变化状态,进而总结分析装配式框架结构的内力系数与层数、跨数的关系,同时推导梁内力系数与节点转动刚度系数的理论关系式。研究表明:在不均匀沉降下,梁柱内力变化与节点连接刚度有关;节点连接刚度影响柱-柱、柱-梁的弯矩传递;在节点连接刚度一定,梁的内力变化与跨数有关,与层数无关;柱的内力变化与跨数有关,在单跨结构中,同时受层数影响;梁端弯矩系数与节点转动刚度系数的关系公式曲线,与模型中拟合的曲线相吻合。     

地铁双线隧道施工对其穿越桥梁安全性分析

地铁隧道施工经常有穿越既有桥梁基础的现象,穿越施工对桥梁造成的潜在威胁受业内普遍重视.北京地铁奥运支线工程奥体中心站—奥林匹克公园站区间隧道(简称奥—奥区间)为双线隧道,在北辰桥处南北向垂直横穿北四环路.北辰桥上部由3座跨线桥构成.为提高桥梁的整体性和抗沉降能力,桥墩基础在设计时已考虑了下穿地铁区间的影响,但是奥—奥区间隧道在施工过程中,不可避免地会对北辰桥产生扰动,从而引起U形槽结构和桥墩的附加沉降.本文以区间隧道穿越北辰桥施工为例,基于FLAC 3D建立的三维模型,对由于双线隧道穿越既有桥梁施工引起的桥梁沉降与变形进行了全过程计算和分析,并对2号桥的盖梁内力进行了检验.结果表明,桥梁构件的变形指标与内力指标都低于容许限值要求.现场监测数据也证明该施工方法的可行性.     

相邻双基坑开挖相互影响二维性状分析

以某实际相邻双基坑工程为原型,利用PLAXIS建立相邻基坑开挖的二维模型,采用HS土体本构模型,分析相邻基坑同步开挖对土体位移、支护结构变形与内力的影响;考虑不同开挖工序和不同基坑间距,分析相邻基坑开挖的影响范围和基坑支护结构在不同开挖工序下的变形特征.对相邻基坑同步开挖下的支护结构位移进行了实测.结果表明,邻近基坑开挖卸荷对基坑间土体沉降、坑底隆起、坑外地表沉降、支护结构内力与变形等产生明显影响.相邻基坑间距、开挖顺序和支护方式是其主要影响因素.     

地基不均匀沉降对上部结构内力和变形的影响

应用有限元软件ANSYS研究了地基基础不均匀沉降对上部结构内力和变形的影响．将结构的柱脚和支座简化为固定端，通过在不同的支座处预先施加给定的位移，来模拟分析地基基础不均匀沉降的影响．以深圳市少年宫“水晶石大厅”为例，研究了几种典型情况．分析表明，地基不均匀沉降方式及沉降量的大小对上部结构内力和变形有显著影响，且结构物的柱距直接影响柱的轴力．     

考虑上部结构和筏板相互作用时的有限元分析

常规设计时,一般把上部结构与基础隔开,柱底固结,然后计算上部结构的荷载,进行内力分析与梁柱设计,但是,这与实际工程不符,地基、基础的刚度会影响到上部结构的内力．本文针对一个框架．筏板基础-Winkler地基模型来分析基础与上部结构的相互作用,研究考虑和不考虑上部结构与基础共同作用时柱子的弯矩和轴力、梁的弯矩和剪力及筏板的沉降与变形．结果显示：常规设计与考虑共同作用相比,常规设计时,上部结构边柱设计偏于不安全,中柱偏于浪费;对于筏板的内力与差异沉降计算值偏大,筏板设计偏于浪费．     

徐变对PC连续梁支座沉降附加内力的影响

为分析徐变对PC连续梁支座沉降附加内力的影响,提出一种通过体系转换描述连续梁支座沉降附加内力状态的思路,借助现行桥梁设计规范给出的连续梁徐变内力重分布公式以及徐变应变的积分表达式,推导出老化系数的计算公式.假设支座沉降的发展规律与混凝土徐变发展规律相同,建立考虑徐变影响的总变位协调方程.选取咸河大桥5跨连续梁为算例,分别计算缓慢沉降和瞬时沉降条件下的徐变次弯矩及最不利弯矩.结果表明:徐变对连续梁支座沉降引起的弹性弯矩有很大的消减作用,使实际最终弯矩不足弹性弯矩的1/2,瞬时沉降时的徐变次弯矩可达到缓慢沉降时的3倍;连续梁支座沉降引起的徐变次弯矩及最不利弯矩均与抗弯刚度成正比,与跨度的平方成反比;连续梁支座沉降最不利弯矩的峰值发生在中间支座截面处,其值为第一个内支座截面最不利弯矩的1.25倍.     

隧道开挖对临近不同相对刚度比桩基影响研究

为了系统研究桩土的相对刚柔性对隧道开挖引起的邻近桩基附加位移和附加内力的影响规律,本文采用三维数值分析方法,通过变换桩基弹性模量、半径和桩长而获得不同桩土相对刚度比,对比分析了隧道开挖时不同桩土刚度比的桩基附加位移和内力的变化规律。结果表明:在桩长一定的情况下,桩土刚度比越大,隧道开挖对桩基产生的附加内力越大,附加位移越小,尤其是桩基的竖向附加沉降量随桩土刚度比的减小而急剧增大;在弹性模量和桩径一定的情况下,桩土刚度比越大,桩基产生的附加内力越小,位移越大。因此,隧道开挖时需对不同刚柔性桩基加以区别保护,研究成果可为隧道施工和设计提供参考。     

含气地层不均匀沉降对盾构隧道结构影响的固-液-气耦合分析

为掌握含气地层中盾构隧道渗漏气引起的地层变形对隧道结构的影响,以苏通气体绝缘金属封闭输电线路(gas-in-sulated metal enclosed transmission line,GIL)项目中江底富含高压浅层气地层为研究对象,利用自主开发的有限元程序,并采用非饱和弹塑性本构模型,对含气地层不均匀沉降对盾构隧道结构的影响进行了三维固-液-气耦合数值模拟分析.结果表明:排气引起的地层不均匀沉降会导致隧道沉降,产生附加内力.其中,渗气口附近沉降位移最大,含气地层下部由于卸荷效应会有少许回弹;同时,沉降位移最大处所在截面的附加弯矩也最大;越远离含气层的位置,截面附加弯矩越小.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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