自锚式悬索桥地震反应有限元分析

以某独塔自锚式悬索桥为工程背景,采用空间有限元程序ANSYS,对其进行了地震反应仿真计算.针对桥塔和桥墩为异形结构(贝壳状弧形壳体),采用8节点实体单元模拟主塔和桥墩.通过迭代计算确定结构初始平衡状态并计入初应力对结构刚度的影响,建立了全桥精细有限元模型.分别对嵌固模型、考虑桩-土相互作用和考虑承台土压力这3种模型进行了不同地震波组合下的动力时程反应分析.计算结果表明:塔根截面的应力水平最高,是结构抗震的关键部位;墩和塔出现了局部应力集中的现象,应力集中的区域在截面突变处和截面的角点处;考虑承台土压力的影响,可以有效减小桩基础的应力;精细有限元模型可以较好地反映结构在地震作用下的易损部位.     

风力发电结构有限元建模及其地震响应分析

为研究不同精细程度的风力发电结构有限元模型在不同分析目的下的适用性,基于2MW三桨叶水平轴风力发电机,采用有限元软件ANSYS建立七种不同精细程度的风力发电结构有限元模型,以风力发电结构地震响应分析为例,得到各模型的响应结果,分别从变形、内力、应力以及应力集中四个方面分析各个模型的计算结果.研究结果表明:在计算风力发电结构的变形时,由于上部机舱及叶片对其影响较小,采用低阶单元即可得到较好的模拟结果;在计算塔底截面剪力和截面弯矩时,考虑机舱及叶片的有限元模型得到的结果较为精确,单元选择时需采用高阶实体单元;不考虑叶片、轮毂以及机舱得到的塔筒截面应力离散性较大,采用壳单元可较好地模拟塔筒截面应力;叶片、机舱等上部结构对门洞局部产生的应力集中影响较大,在计算时建议应用塔筒采用壳单元、门洞局部采用实体单元的多尺度模型进行模拟.     

焦炭塔地震响应的参数化有限元分析

采用有限元方法对焦炭塔建立参数化模型,分别应用地震反应谱理论和时间历程响应理论,分析了焦炭塔在不同工作阶段的地震响应,得到了结构的位移响应及应力分布,对参数化有限元分析的实施方法进行了探讨.为塔设备的地震分析设计提供了一种方便的实现方法.     

考虑土―结构相互作用的运转状态风电塔抗震分析

针对某陆上风电场1.5 MW风电塔结构,建立了"塔筒―基础―地基"整体三维精细有限元模型,研究土―结构相互作用对风机运转状态下风电塔结构地震动力响应的影响规律.在风机运转状态下,使用FAST程序把风速时程转化为风荷载时程输入模型,并使用EERA程序进行土层地震反应分析得到模型土层底部的地震波,作为地震激励进行输入,对风电塔进行模态分析并计算风电塔地震动力响应.研究表明,考虑土―结构相互作用效应会引起风电塔体系自振频率降低,并显著增加风电塔的结构动力响应.     

不同梯段板厚度楼梯对钢筋混凝土框架结构地震反应影响分析

为研究楼梯对结构地震反应的影响,利用有限元软件ETABS建立了1个不包含楼梯的钢筋混凝土框架模型和2个包含不同梯段板厚度楼梯的钢筋混凝土框架模型(梯-框脱离模型),分别采用振型分解反应谱法和时程分析法对3个模型进行了地震反应对比计算分析.结果显示:考虑楼梯参与结构整体地震计算后,结构的振动模态、抗侧刚度分布、及梯问框架...     

考虑土-结构相互作用的特高压变压器抗震性能分析

特高压变压器是变电站内重要的电气设施,进行变压器抗震计算时一般把地基基础考虑为绝对刚性,忽略了土体的影响。本文研究基于有限元数值仿真建立了土体-变压器的抗震分析模型,该模型考虑了土体在地震载荷下的非线性力学行为,并研究了变压器刚度及阻尼比变化对变压器抗震性能的影响。结果表明：数值模型与试验结果的频率误差在10%以内;在土体非线性力学行为影响下,随着地震峰值加速度的增加,特高压变压器的地震响应呈现出非线性增加的趋势;在0.2 g、0.4 g、0.8 g(g为重力加速度)地震激励下高压套管应力与试验误差分别为3.3%、2.6%、5.6%,说明了仿真分析力学模型的有效性。随着变压器刚度的增加,作为变压器薄弱环节的高压套管应力减小;阻尼比增加,设备的地震响应先增加后减小。研究成果可为特高压变压的抗震设计提供指导。     

结构参数对低层轻钢房屋抗震性能影响分析

为研究不同结构参数对低层轻钢房屋抗震性能的影响,以已有试验结果为基础,采用ABAQUS软件建立轻钢房屋的有限元模型,计算得到的房屋自振频率、加速度反应及位移反应等均与试验结果吻合较好,验证了有限元模型的正确性.在此基础上,对验证后的房屋模型在9度多遇及9度罕遇地震作用下进行了变参数分析.研究结果表明:采用增加覆面板数量、增设柱间斜撑的墙体构造形式可提高房屋的自振频率、加速度及位移响应;但改变覆面板材料对整体结构的动力特性及地震响应影响较小;墙体开洞率对房屋在地震作用下的结构响应影响明显,因此墙体开洞率不应大于29.09%;轻钢房屋长宽比减小,平面布置更规则,结构自振频率增大,加速度及位移响应降低.     

地震对传输塔影响的研究

用MARC软件对传输塔进行模态分析,求出结构的自振周期;其次,将传输塔分层,求出结构的重力荷载代表值,再根据建筑场地类别、设防烈度等条件和地震基本理论求出水平地震作用和竖向地震作用;然后利用地震和有限元理论,用MARC软件对其进行静力分析。根据应力、位移情况观察其危险点,并将其结果与没有地震作用的情况相比较。     

强震作用下独塔斜拉桥模型的非线性动力响应分析

建立了基于隐式积分和显式积分的2种有限元模型,对独塔斜拉桥振动台试验中得到的地震响应特性及其破坏模式进行了模拟.然后,利用基于隐式积分的有限元模型,分析了行波效应和索塔梁耦合振动对独塔斜拉桥地震响应特性的影响.结果表明:基于隐式积分的有限元模型可以有效地模拟斜拉桥发生破坏前的地震响应特性,而基于显式积分的有限元模型则可用于模拟独塔斜拉桥在地震作用下发生破坏的全过程;由于输入地震波频谱效应以及视波速各异,行波效应对独塔斜拉桥地震响应特性的影响各不相同;在强震作用下,模型会发生索塔梁耦合振动,导致主塔的纵桥向位移响应明显增加.     

带箱形转换层高层建筑结构的抗震性能研究

进行了带箱形转换层高层建筑结构模型的地震模拟振动台试验.采用微粒混凝土制作1/10比例的结构模型,得到结构在地震作用下的动力特性以及加速度、位移等地震响应,研究了模型结构的受力机理和破坏模式.在试验研究的基础上,采用有限元分析程序对原型结构进行抗震分析,理论分析与试验结果吻合较好.研究表明,该结构体系总体抗震性能良好,大震作用下仍具有较好的工作性能,能满足我国抗震设计规范的要求.     

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-