平面张弦梁结构极限跨度研究

国内外张弦梁的兴建方兴未艾,而该结构的极限跨度论述鲜有报道。就此问题从结构设计因素出发,根据张弦梁的受力特点及拉索和上弦拱梁的材料极限强度条件,推导了平面张弦梁结构的极限跨度公式,并对平面张弦梁极限跨度的影响因素进行了分析。     

张弦梁结构刚度参数分析与优化设计

针对现有关于张弦梁结构基于刚度的参数分析和优化研究较为缺乏的不足,采用有限元方法对此问题进行研究。首先,结合某实际张弦梁结构模型并通过变化其主要参数值(如上弦抗弯刚度与下弦轴向刚度比值、上弦轴向刚度与下弦轴向刚度比值、高跨比和下弦索面积等)建立了多个结构模型,然后进行相应刚度分析,得到了这些主要参数对结构竖向整体刚度的影响规律和刚度优化设计的建议。结果表明:在参数分析范围内,当结构高跨比、上弦轴向刚度与下弦轴向刚度比值和上弦长细比一定时,张弦梁结构刚度近似与下弦索面积成正比;在工程实践中,为了在经济效果较优的情形下获得较大的刚度,建议张弦梁结构选用较大的结构高跨比、索垂跨比和较小的上弦轴向刚度与下弦轴向刚度比值。     

波形钢腹板钢管混凝土梁有限元分析及参数研究

提出新型组合结构——波形钢腹板钢管混凝土梁三维有限元计算方法.应用ANSYS程序对试验梁进行了双重非线性有限元分析,计算结果与试验结果吻合较好.应用有限元方法,以波形钢腹板厚度、弦管壁厚以及管内混凝土等级为参数对其对受力性能和极限承载力的影响进行了分析.结果表明,对于以上弦管局部屈曲为特征的A梁,若要提高其承载力,应增加上弦管的壁厚;而对于极限承载力受下弦管受拉屈服控制的B、C梁,则要增大下弦管的壁厚.上下弦管是否采用钢管混凝土对梁的受力性能与极限承载力有显著的影响.然而,管内混凝土的等级对梁的极限承载力影响很小.波形钢腹板应具有足够的厚度以避免其局部屈曲破坏.在保证这一板厚的前提下,波形板厚度对梁的承载力影响并不大,承载力计算中可以忽略其对梁的抗弯能力的贡献.     

预制管廊横向接头抗弯力学模型及取值方法

接头导致预制预应力综合管廊结构刚度分布不均匀,内力以及变形发生变化,而抗弯刚度是衡量管廊接头性能的重要指标以及评价管廊结构整体力学性能的重要参数.在考虑横向接头截面实际构造形式以及受力变形特点的基础上,通过内力平衡和变形协调条件,建立了可以表征接头截面从受力到破坏各阶段的力学模型以及相应的理论解析表达式.通过数值模拟的方法对接头抗弯刚度影响因素进行了敏感性分析,并在此基础上将理论计算结果与数值模拟结果进行对比,最后根据得出的抗弯刚度变化规律提出了管廊横向接头抗弯刚度两阶段取值方法,研究结果可为预制管廊的设计和理论分析提供参考.     

贯通隔板全螺栓节点抗连续倒塌分析

以钢管混凝土隔板贯通式全螺栓节点为研究对象,设计了一个三柱两跨式平面框架结构,采用静力加载的方式模拟结构倒塌的全过程,考察节点的受力变形、抗力机制、破坏现象和应变发展.建立ABAQUS有限元模型对结构失效模式进行受力分析.试验和有限元结果表明,倒塌全过程经历4个阶段:梁机制、混合作用、悬线作用和破坏.结构的抗倒塌能力取决于抗弯和抗拉能力,设计节点可以满足FEMA-365的转角要求,结构中的悬线作用出现在破坏阶段前.构件破坏发生在中节点H型梁下翼缘处,孔壁撕裂导致裂缝延伸至腹板使H型梁出现断裂.由于螺栓孔对翼缘的削弱,建议对螺栓连接H型钢翼缘进行构造加强,以保证连接的有效性.     

自锚式梁下斜张简支桥梁破坏模式试验与数值研究

为研究自锚式梁下斜张简支桥梁的破坏模式和机理,进行了10m跨径简支试验梁的荷载试验与三维有限元精细化模拟分析,并对斜张索截面面积、撑杆高跨比及主梁的截面形式等参数对破坏模式的影响进行了分析.结果表明,试验梁破坏模式为梁下斜张索屈服断裂.主梁进入塑性后其抗弯刚度降低,结构的卸载效率值提升,使得斜张索索力随外荷载的增长斜率增大,主梁荷载弯矩随外荷载的增长斜率减小,而主梁的抵抗弯矩提升较快,从而产生了上述破坏模式.参数分析表明,增大索截面面积和降低撑杆高跨比将使得结构发生主梁先压溃而斜张索未屈服的另外一种破坏模式.主梁长细比较大的板梁结构的破坏模式与模型试件相同,所能承受的最大跨中荷载略低于试验梁,其材料成本低于工字型梁结构.     

装配式张弦梁钢支撑结构力学性能分析

为明晰装配式张弦梁钢支撑系统中预应力张弦梁结构的力学性能，采用ABAQUS有限元软件对张弦梁结构进行数值模拟分析.通过张弦梁撑杆预应力、撑杆截面尺寸、冠梁截面尺寸和桩基侧向刚度等影响因素分析张弦梁钢支撑的受力性能.利用MIDAS有限元软件对张弦梁钢支撑进行整体建模分析.结果表明：张弦梁靠近对撑部分的拉杆的承载能力对整个张弦梁的承载力起决定作用；增大撑杆预应力和桩基侧向刚度对张弦梁钢支撑承载能力有明显增强；增大撑杆截面和冠梁截面对张弦梁系统的承载能力提高不明显；张弦梁钢支撑系统的基坑位移处于预警值范围内，支撑系统对基坑位移有较好的控制作用.     

新广州站中央采光带杂交结构受力性能分析

为了了解新广州火车站中央采光带杂交结构体系的受力性能,讨论了其下部索杆体系的预应力设计水平,分析了结构体系中柔性构件对其静力性能的影响,并对其进行了特征值屈曲分析和非线性屈曲分析,文章最后讨论了上弦钢杆件截面、钢拉杆和下弦拉索截面及其预应力对结构竖向刚度的影响.计算结果表明:杂交体系中下部索杆体系和上部面内钢拉杆可以较大地提高结构的刚度;该杂交结构体系满足整体稳定性的要求,但其端部区域是结构稳定的薄弱环节之一;结构的竖向刚度随着钢杆件截面的增大而增加;上弦钢拉杆的截面及预应力的增加对结构竖向刚度有一定的提高;下弦拉索截面对结构刚度的影响较大,但是其预应力值的影响较小.     

X型圆钢管相贯节点刚度试验

为了验算相贯节点刚度对钢管结构的受力性能及整体稳定性的影响,以某单层网壳结构体育馆为背景,进行了X形相贯节点轴向刚度和抗弯刚度的试验研究.文中介绍了试验方案和主要试验结果,对试件的破坏机理进行了分析.试验结果表明,当支管与主管直径相差较多时,节点轴向刚度和抗弯刚度均较弱,节点的半刚性能对结构的受力性能尤其是整体稳定性的影响不容忽视;当支管与主管直径接近时,节点轴向刚度和抗弯刚度均较大,基本能够满足节,最刚接的要求.     

钢管拱面内非对称加载试验

进行了钢管拱面内非对称加载全过程试验.试验结果表明,钢管模型拱截面抗弯刚度小,受力过程弯曲变形较大.模型拱截面在受力全过程以弯矩作用为主,轴力较小,轴力与挠度交互作用的几何非线性影响较小.结构破坏属于以材料非线性影响为主的二类稳定问题.结构破坏时,塑性区域的分布较广,应力重分布现象明显,其极限承载力不能采用极限状态法.图6,表1,参6.     

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.     

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.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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.