不等跨蜂窝式现浇混凝土空心双向板的弯矩计算

对周边支承蜂窝式现浇混凝土空心双向板的受力机理等问题进行了研究.结果表明,该种板不同于密肋和交叉梁楼板,它的受力机理等同于实心板.最后,采用不等跨连续板弯矩分配法进行了工程实例计算,给出了蜂窝式空心双向板的构造要求.     

在役空心板桥梁拆除构件室内破坏试验

为准确评估服役24年后空心板梁的剩余承载能力,将济青(济南—青岛)高速公路改扩建工程中一空心板梁桥拆除并运回实验室进行破坏试验,对空心板关键位置的静力响应指标,如梁体挠度、钢筋应变、混凝土应变及裂缝发展等进行测试,同时对梁体在主要荷载步下的动力特性进行测试。研究结果表明:空心板跨中挠度-正弯矩曲线呈明显的双折线变化规律,实际塑性转折点对应弯矩值分别为公路-Ⅰ级、汽-超20设计荷载效应的2.50倍及4.09倍;空心板进入塑性阶段主要由部分钢筋率先屈服所引起;破坏试验过程中,空心板中性轴由最初位置上移了6.9 cm,受此影响,距离梁底较高的混凝土压应变呈现先增后减的变化规律;进入塑性阶段前,腹板主裂缝宽度增长相对缓慢且基本在0.3 mm以下,之后裂缝增长明显而跨中弯矩增长很小;就动力特性而言,前期试验中空心板自振频率变化微弱,而进入塑性阶段后,空心板一阶振动频率下降明显,基于模态柔度差可进一步对进入塑性阶段前的空心板损伤程度进行量化;由破坏试验所确定空心板梁实际抗弯承载力为规范计算承载力的1.52倍。     

GFRP-混凝土组合连续板的静力性能试验研究

为提高钢-混凝土组合梁桥桥面板的耐久性,研究GFRP(玻璃纤维增强复合材料)-混凝土组合连续板的变形及裂缝宽度,设计了3片负弯矩区具有不同钢筋配筋率的GFRP-混凝土组合连续板,并对其进行了对称加载试验,重点考察了连续板的破坏模式、变形、裂缝宽度和应变分布等力学特性.结果表明:3片连续板均发生了弯剪破坏;破坏时板端GFRP槽形板与混凝土之间无明显滑移;随着负弯矩区配筋的增强,连续板全过程变形减小;在钢筋屈曲前,连续板正负弯矩区的应变分布基本符合平截面假定.试验研究和理论分析结果的对比表明:可以采用现行桥梁规范中考虑混凝土开裂区域刚度变化的等效刚度计算GFRP-混凝土连续板的等效刚度,并通过文中计算方法获取连续板的变形;此外可以采用现行规范JTG D62—2004中钢筋混凝土的裂缝宽度计算方法计算连续板负弯矩区的混凝土裂缝宽度.     

不同构造形式绿色混凝土叠合板受弯性能试验

为推动绿色再生类材料在叠合楼板中的应用,将不同性能要求的钢纤维增强绿色混凝土材料应用于叠合板中,研究不同构造形式所组成的钢纤维绿色混凝土叠合板受弯性能差异.开展了6块钢纤维增强绿色混凝土叠合板和2块普通混凝土叠合板足尺试件的抗弯性能对比试验.得到了其破坏形态、荷载-跨中挠度曲线、荷载-跨中板底受力钢筋应变曲线及荷载-跨中板顶面混凝土压应变曲线等特征参数,对比分析了各试件的破坏机理、变形特征、裂缝分布规律.研究结果表明,钢纤维增强绿色混凝土叠合板与普通混凝土叠合板相比受弯破坏过程类似,均经历了弹性阶段、弹塑性阶段及破坏阶段,且裂缝、挠度发展均较为充分,未有突然断裂或沿叠合面出现水平裂缝等破坏现象,均具有较好的延性;同时,不同的预制底板构造形式对叠合楼板的受弯性能也有较大影响,其中配置钢筋桁架的叠合板,尤其是附肋钢筋桁架对叠合板的受力性能有较为显著的提高;开裂荷载及极限承载力计算应考虑构造形式及不同混凝土材料预制底板对所组成叠合板受弯性能的影响.     

劲性钢筋轻骨料混凝土梁正截面受弯数值模拟

为研究劲性钢筋轻骨料混凝土构件的抗裂性能,采用跨中集中荷载的加载方式,通过数值模拟,分析劲性钢筋轻骨料混凝土梁受弯构件变形与荷载的关系。模拟结果表明:劲性钢筋轻骨料混凝土梁刚度较大,但破坏时挠度很大,有很好的延性。当受压区混凝土压碎破坏时,试验梁仍具有很大的承压能力。随着跨中荷载的增大,梁的位移变形也随之增多。跨中荷载增加到40 t时,梁的位移变形开始大幅度增大,导致混凝土开裂。混凝土开裂后,试件截面刚度退化,裂缝宽度增幅显著,裂缝宽度逐渐加宽。试件梁开裂后,裂缝宽度随荷载变化的增长趋于稳定,抗裂性能较好。模拟结果与试验值相符。     

带开孔板连接件的压型钢板‒混凝土组合桥面板疲劳性能试验研究

为研究带开孔板连接件（PBL连接件）的压型钢板?混凝土组合桥面板的疲劳性能，设计制作了1块连续组合桥面板试件，试件长9.25 m，宽1.5 m，最大混凝土板厚24 cm，压型钢板厚3 mm；开展了单点变幅疲劳加载和间隔性的静力加载试验，测试了试件的跨中挠度、钢底板和负弯矩区钢筋应变，观测了负弯矩区混凝土裂缝的分布与发展，测量了最大裂缝宽度，得到了组合桥面板试件受力性能随疲劳加载次数增加而退化的过程以及和试件的疲劳破坏形态。试验结果表明：组合桥面板试件的受力性能随着疲劳加载次数的增加而发生退化；在经过累计600万次疲劳加载后试件未发生破坏，表明其具有较好的抗疲劳性能；组合桥面板试件最终的疲劳破坏形态为跨中截面钢底板断裂破坏，裂纹最先萌生于PBL连接件与钢底板焊接位置，同时静载下负弯矩区混凝土的最大裂缝宽度达到了0.2 mm，利用线性损伤准则分析了已有的S-N（应力幅?循环次数）曲线对组合桥面板的适用性。     

四边固定蜂窝式空心双向板按弹性理论的挠度数值解

采用有限元法对比分析了蜂窝式空心板的受力特点,指出了蜂窝式空心板与密肋楼板和井式楼板受力机理的不同.给出了蜂窝式空心板的平衡微分方程和弯曲及扭曲刚度的计算公式,使用数值解法求出了四边固定蜂窝式空心双向板按弹性理论的挠度解,并结合算例进行了有限元分析验证.挠度数值解与有限元分析结果的误差很小,可用于四边固定蜂窝式空心双向板在竖向均布荷载下挠度的求解.     

UHPC加固箱梁顶板受弯性能试验研究

提出密配筋UHPC(超高性能混凝土)加固钢筋混凝土箱梁顶板方法,以消除混凝土箱梁顶板因开裂导致结构承载能力和耐久性普遍降低两类病害.为探究该加固方法在集中荷载下的箱梁顶板横向受弯性能,对3块足尺箱梁顶板局部模型进行试验研究.试验结果表明:负弯矩作用下,受拉的UHPC层显著提高了加固板的抗裂性能和刚度;加固试验板的开裂强度取决于UHPC的弹性抗拉性能;裂缝宽度为0.2mm时的持荷水平相对于未加固试验板提高了255.8%;当裂缝宽度小于0.27mm时,荷载与最大裂缝宽度关系近似线性.正弯矩作用下,UHPC层受压,加固试验板的开裂强度取决于封闭裂缝所用黏胶的抗拉强度;因为普通混凝土区域裂缝出现较早,正弯矩加固板在前期表现出略微偏大的挠度,但后期挠度和裂缝宽度的增长速度均明显小于未加固板,致密的UHPC层为箱梁顶板提供良好的防水性能,加固层对正弯矩试验板刚度的提高和裂缝发展的控制效果较为明显;破坏形态符合预期,破坏荷载与理论计算结果吻合良好.     

高强钢筋高强混凝土预应力梁抗弯性能试验研究

通过对12根高强钢筋高强混凝土预应力梁的抗弯试验,观测试验梁的破坏现象和失效过程,研究混凝土强度等级、非预应力高强钢筋配筋率、预应力钢筋配筋率等因素对其抗弯性能的影响规律.试验结果表明,高强钢筋高强混凝土预应力适筋梁破坏过程包括开裂前阶段、带裂缝工作阶段和钢筋屈服后直至失效3个阶段,各阶段破坏模式与普通钢筋混凝土梁受弯破坏相似,均为延性破坏.混凝土强度等级以影响钢筋屈服后的抗弯性能为主,高强度等级混凝土试验梁的后期承载力下降较小.非预应力筋配筋率显著影响试验梁开裂后的抗弯性能,即相同变形时,配筋率越高承载力越高.相同张拉控制应力条件下,预应力筋配筋率越高开裂弯矩越大;相同弯矩作用下,预应力配筋率越高变形越小,其极限承载力也越高.     

预应力高强混凝土矩形支护桩的受弯性能

针对预应力混凝土预制桩在基坑支护中的应用,开发新型的预应力高强混凝土矩形支护桩。通过9根矩形支护桩的受弯性能试验,研究了矩形支护桩的受弯破坏特征、裂缝开展情况和受弯承载力。结果表明:在外荷载作用下,矩形支护桩变形体现了很好的弹性和延性;矩形支护桩截面的应变分布符合平截面假定;矩形支护桩的抗裂弯矩实测值与计算值之比平均为1.33;实测极限弯矩与理论计算值基本接近。基于试验结果,提出对矩形支护桩抗裂弯矩和极限弯矩计算方法的修正建议,计算结果与试验结果吻合较好。对比发现,在相近的成本条件下,矩形支护桩比空心方桩受弯承载力增加10%～20%。     

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