整体式桥台无缝桥梁抗洪性能分析

针对目前尚无整体式桥台无缝桥梁抗洪性能研究的现状,通过有限元软件MIDAS/Civil对福建永春上坂大桥的受力性能进行分析,并将分析结果与实桥的静载试验结果进行比较,验证了模型的正确性.以上坂大桥为原型,建立了相同上部结构形式、不同跨数的无缝与有缝桥梁的有限元模型,并对各桥的支座反力、桥墩内力以及墩顶位移等进行比较和分析.通过比较得出:当跨数大于2跨时,整体式桥台无缝桥梁在洪水作用下弹性阶段的受力特性能优于普通有缝桥梁;当将跨数减少至2跨后,整体式桥台无缝桥梁的竖向受力和横桥向的受力明显优于有缝桥梁.分析结果表明,跨数大于2跨使得整体式桥台无缝桥梁的优势在弹性阶段不能充分发挥;当桥梁的跨数为单跨或2跨时,整体式桥台无缝桥梁在弹性阶段的受力性能和抗倒塌能力相对于有缝桥梁都有明显的提高.     

桥台高度对整体式桥台桥梁内力的影响分析

整体式桥台桥梁是一种无伸缩缝且主梁与桥台连为一体的新型桥梁结构,目前在国内实际工程中应用较少而且未形成一套完善的设计体系,其结构设计仍处于技术摸索阶段。采用Midas/Civil有限元软件建立3×16 m中等跨径整体式桥台桥梁的二维弹簧框架模型;并依托实际工程——富裕工业园跨线桥试验数据,对有限元模拟方法和模型的受力性能进行了验证。在不同地质条件和温度荷载作用下,通过调整有限元模型探讨了桥台高度在3~6 m变化时对中等跨径整体式桥台桥梁结构受力性能的影响。计算表明,在3~6 m范围内,适当改变桥台高度不会对设计造成太大影响,这为中等跨径整体式桥台桥梁的结构设计提供了参考依据。     

均匀温度下多跨半刚接整体桥受力性能

以某多跨空心板梁桥改造为半刚性节点整体桥为例,建立考虑桩-土相互作用的桥梁有限元实体模型,进行上、下部结构不同连接方式对温度变化作用下结构受力性能影响分析. 结果表明：主梁与桥台连接方式对整体桥受力的影响大于主梁与桥墩处的连接方式;主梁与桥台刚接时,在温度变化作用下,结构内产生的附加轴力、弯矩远大于主梁与桥台采用半刚接的. 对半刚性节点进行参数分析,结果表明,橡胶套壁厚是影响主梁弯矩的主要因素,橡胶垫及钢棒直径对主梁弯矩影响较小;橡胶套壁厚和钢棒直径对桥台处柱-桩基的影响较大,对桥墩处柱-桩基弯矩影响较小,可忽略不计.     

结构刚度对无缝桥梁整体受力影响研究

依据研究内容及结构刚度基本理论,建立了只包含主梁、桥台及桥台桩基三个结构的单跨整体式无缝桥梁,分别单一的改变三者刚度,得出其刚度变化对结构受力的影响,并绘出了影响变化曲线。     

在水平荷载下整体式桥台桥梁受力分析

目的为找出在升温温差和降温温差下桥台桩柱内实测应力的分布和变化规律,分析水平荷载作用下整体式桥台桥梁的受力性能.方法以富裕工业园跨线桥为工程背景,以试验桥的左侧桥台作为试验对象,采用计算精度高的P-y曲线法对整体式桥台桥梁在制动力作用下的受力进行分析.结果通过与试验桥桥台桩柱内应力试验实测值的对比分析所得出P-y曲线法计算桩土相互作用的精度高于"m"法.试验桥的单侧桥台在制动力作用下的受力与在均匀温差作用下的受力具有相似性.结论采用P-y曲线法分析在水平荷载下整体式桥台桥梁的受力特性具有较高的可行性.     

整体式桥台H形钢桩基受力性能试验研究

为研究温度或地震荷载作用下H形钢桩基的受力性能,分别开展了平衡与非平衡土压力状态下H形钢桩基-土相互作用拟静力试验研究,对比分析了整体桥H形钢桩基桩侧土抗力、桩身应变和弯矩等.结果 表明,不平衡土压力会对正向加载下的桩基受力性能产生显著影响,但对负向加载下的影响不大.桥台-H形钢桩(AHP)试件和台后不平衡土压力下H形钢桩(UHP)试件正向加载时的桩侧土抗力、桩身应变和弯矩显著大于负向加载,而平衡土压力状态下的H形钢桩(HP)试件正向与负向加载时的桩侧土抗力、桩身应变和弯矩基本一致.AHP试件的桩侧土抗力、桩身应变和弯矩最大,UHP试件次之,HP试件最小,故AHP试件更快进入弹塑性状态.     

两跨连续梁模型桥地震响应影响因素研究

以公路钢筋混凝土连续T梁桥为背景,结合振动台试验所用两跨连续梁模型桥地震响应,开展跨径、跨数、斜交角对该模型桥地震响应影响的数值研究,结果表明:在纵向地震输入时,跨径增加,支座水平剪力越大,墩梁纵向相对位移越大;跨数越多,支座和桥墩受力越大,远离固定墩侧的墩梁相对位移提高;斜交角增大,支座和桥墩受力由单向变为双向,纵向地震响应降低而横向地震响应不断增长;跨数和跨径增大时,主梁加速度响应的变化与地震动特性有关,而斜交角增大则纵向加速度不断减小.     

斜交板拱空间受力特性参数敏感性分析

为研究不同结构参数下斜交板拱的受力特性,建立不同斜交角度、矢跨比的空间斜交板拱有限元模型,对其结构响应进行对比分析.结果表明:随着斜交角度的增大,拱脚反力极不均匀,板拱的扭转和翘曲效应越来越明显;矢跨比变化时,斜度对斜板拱的受力特性影响规律相同,但结构空间受力特性的强度明显不同.     

基于统一边界和梁格模型的整体式桥台桥梁分析

取消伸缩缝及支座的整体式桥台桥梁可以避免伸缩缝的病害及对行车的影响.由于桥台处的上部结构与下部结构浇筑在一起,整体式桥台桥梁的上部结构受力受到下部结构乃至土体的影响,使其计算需要将上下部结构综合考虑,计算方法也更为复杂.提出一种思路,以实现上部结构在不同荷载作用组合下的验算与调整.以一座两跨的整体式桥台桥梁为依托工程,...     

双拱形渡槽桥台桩基承载力三维有限元分析

采用ANSYS软件,对山西省北赵引黄提水工程双拱形渡槽、桥台、桩基和地基土体进行三维有限元模拟分析,得出了自重及温升荷载下的结构应力变形规律。针对桥台水平位移引起桩体的弯曲变形,导致桩与土之间作用力分配难以用一般性理论进行计算,将地基-桩体-桥台-拱跨整体建模,进行整体分析,并重点研究了拱端水平推力对桩基及土体应力、位移和变形的影响。     

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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-