永修特大桥拱墩连接处受力特性分析

文章以昌九客运专线上永修特大桥为例,通过拱墩连接处局部空间有限元精细分析和1:3的缩尺模型试验,对下承式刚架系杆拱桥拱墩连接处的受力特性作研究。研究结果表明:预应力螺纹钢筋的预应力只对下锚板上方的混凝土产生效应,下锚板以下部分不受影响;系杆拉力大小只影响系杆以下部分墩柱的受力情况,对系杆以上部分刚架几乎无影响;拱肋轴压力很大,拱墩连接处不考虑螺纹钢筋预应力时拱座混凝土已经受压,因此,预应力可适当减小。     

大跨度刚架系杆拱桥自振特性的模态分析

采用大型通用有限元程序ANSYS对一座两跨钢管混凝土刚架系杆拱桥建立了空间有限元计算模型,采用模态分析方法对桥跨结构的自振特性进行了分析,计算了桥梁前10阶的自振频率,得出了该桥成桥状态振动形态的基本特征.通过对主要设计参数的对比分析,得出了矢跨比及拱肋刚度对刚架系杆拱桥自振性能的影响规律,可为该类桥梁的设计、研究、健康监测和维护提供参考.     

北川河钢管混凝土刚架系杆拱的结构分析

以青海省西宁市北川河桥为例 ,建立钢管混凝土刚架系杆拱桥空间有限元模型 ,对主拱肋施工阶段进行静力分析和稳定分析 ;对全桥使用阶段进行静力分析、整体稳定分析和动力特性分析 ;并对系杆施加预应力的大小等若干问题进行讨论 ,研究结果有助于了解此类桥梁结构的受力性能     

刚架拱桥拱索加固体系的受力特性

对某钢筋混凝土刚架拱桥提出了采用拱索体系的加固方法,用空间有限元对其受力特性进行了分析,并与试验测试值进行了比较.研究结果表明,对于用钢缆索斜拉法加固刚架拱桥的新结构,其空间受力效应明显;对处于软土地基上的桥的动力特征分析,必须考虑桥台与地基土壤之问的弹性抗力作用;原拱桥的面外刚度比面内刚度大,反映原拱桥具有足够的横向刚度.     

钢箱拱桥中CFRP系杆受力性能试验研究

结合怀化某大桥,按照相似原理,建立了碳纤维系杆拱桥缩尺试验模型,对其受力性能进行了试验研究;并采用空间有限元分析软件Midas/Civil对模型桥使用阶段各工况进行了空间模拟分析.试验结果表明:CFRP系杆拉力和拱脚水平位移的实测结果与有限元分析结果基本吻合;用有限元程序的计算分析结果指导模型桥测点选取和加载等工作是可行的,其分析结果是正确的;CFRP作为系杆其总预应力损失率的最大测量值为2.1%,预应力损失较小,其预应力值稳定.     

钢管混凝土系杆拱桥拱脚一致多尺度建模及分析

针对传统精细化模型在分析钢管混凝土系杆拱桥拱脚时,存在局部边界模拟困难、分析精度难以保证等问题,基于结构一致多尺度建模理论,提出将全桥模型通过合理的连接方式统一到拱脚精细化模型上的思路,建立了适用于钢管混凝土系杆拱桥拱脚受力性能分析的一致多尺度建模方法,并对一座计算跨径96 m、矢跨比为1/5的下承式钢管混凝土系杆拱桥的拱脚受力性能和安全性进行了研究.研究结果表明:一致多尺度建模在极大地减小了计算量的同时,还可以准确模拟钢管混凝土系杆拱桥等复杂结构的局部边界条件,并预测拱脚构造的力学行为;钢管混凝土系杆拱桥拱脚结构总体受力合理,但在预应力钢筋锚固区及支座附近区域存在较为明显的应力集中现象.     

下承式哑铃型钢管混凝土系杆拱桥静力性能研究

目的 研究下承式哑铃型钢管混凝土系杆拱桥在施工过程中的应力与变形,为实际工程应用提供理论依据。方法 采用有限元软件Midas/Civil建立钢管混凝土系杆拱桥有限元模型,分析拱桥施工过程中应力、变形的变化规律及结构参数变化对拱肋受力的影响。结果 钢管与混凝土峰值压应力均位于拱脚截面,考虑收缩徐变影响时拱脚上弦管压应力较二期荷载作用下提高61%;与先浇筑上管混凝土相比,先浇筑哑铃型下管混凝土时,组合截面中性轴下移且应力变化幅度较小;拱肋含钢率介于4%～9%时,增大钢管壁厚与直径可使拱脚截面、1/4截面、跨中截面峰值压应力、峰值挠度降低;拱肋内倾角为0°～13°时,拱肋截面峰值挠度随内倾角的增大呈现先减后增趋势,其中内倾角为7°时挠度最小。结论 考虑运营期拱肋混凝土收缩徐变时,哑铃型拱肋处于全截面受压状态;对于采用哑铃型截面的下承式钢管混凝土系杆拱桥,先浇筑拱肋下管混凝土可使系杆拱桥体系受力更加合理;内倾角变化对拱肋峰值挠度有一定影响。     

拱脚受力分析和破坏机理探讨

利用有限元软件Ansys,建立了钢管混凝土系杆拱桥拱脚部位的三维有限元空间模型,模拟了该部位在两种最不利荷载工况(弯矩最大和轴力最大)下的受力情况.计算结果表明,拱脚节点以受压为主,节点内部应力分布均匀,总体受力合理,满足设计要求.同时,根据材料破坏理论,找出了最有可能产生破坏的位置,并提出了相应的预防措施.     

深圳北站大桥静力计算分析

以深圳北站大桥设计为研究对象,建立全桥空间计算模型,计算分析了大跨钢管砼刚架系杆拱桥的受力性能,为此类桥梁的设计提供数值参考     

东江水沟桥梁方案比选

从造价、工期、施工难度、景观等方面对下承式系杆拱桥、空腹式刚架拱、连续箱梁等几种常见的桥型进行比较选择,最后确定下承式系杆拱桥为实施方案。     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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