高温后方钢管全再生混凝土短柱轴压试验研究

为了研究不同冷却方式下高温后方钢管全再生混凝土短柱的轴压力学性能,设计制作9根短柱试件依次进行高温试验和轴心受压试验,探讨历经温度(20℃、200℃、400℃、600℃、800℃)和冷却方式(自然冷却、喷水冷却)对轴压破坏形态、极限承载力、初始刚度、刚度退化及延性的影响。试验结果表明:试件最终破坏形态为钢管撕裂和钢管鼓曲斜压破坏;高温作用后试件极限承载力降低较为显著,但受自然冷却和喷水冷却的影响不明显;试件初始刚度随温度的升高而不断降低,喷水冷却作用对试件初始刚度有二次削弱;试件刚度退化曲线经历了平台段、快速下降段、平缓下降段、平稳段,冷却方式对试件刚度退化的影响不大;试件的延性随温度的升高呈先降低后升高的趋势,喷水冷却作用会降低试件的延性。     

高温后钢筋混凝土黏结性能试验研究

对在不同受热温度、冷却方式和加载制度下钢筋混凝土黏结性能进行试验研究,分析了不同条件下钢筋混凝土的黏结-滑移曲线和极限黏结应力、极限滑移.钢筋混凝土试件的受热温度分别为250℃,450℃和650℃,冷却方式分为自然冷却和喷水冷却2种,加载方式考虑单向拉拔试验和循环往复加载.结果表明,受热温度、冷却方式和加载制度对高温后钢筋混凝土的黏结性能有很大影响.     

高温喷水冷却后钢管高强混凝土轴压性能研究

为揭示高温喷水冷却后钢管高强混凝土的轴压性能,以历经温度、冷却方式、恒温时长和混凝土强度等级为变化参数,设计了20个钢管高强混凝土短柱试件,进行高温喷水冷却后的静力单调轴心受压试验.观察高温喷水冷却后试件及试块的表观变化和破坏形态,分析各变化参数对高温喷水冷却后钢管高强混凝土轴压性能的影响规律,给出了极限承载力计算公式...     

钢筋混凝土简支梁高温力学性能的试验研究

通过对8根足尺钢筋混凝土简支梁进行火灾模拟试验,并对构件高温冷却后进行破坏性试验,得到了构件在高温作用下的温度场分布、变形规律和构件在不同的配筋、不同的冷却方式和不同的升温时间下的剩余极限承载力,并对各种工况下的构件受损程度进行了对比分析.试验结果表明,构件保护层厚度越小,升温时间越长,配筋率越低,则火灾对梁的损伤程度越大,喷水冷却构件剩余极限承载力较炉中冷却剩余极限承载力大.     

高温后掺纳米CaCO_3混凝土劈裂抗拉性能研究

为研究不同高温后掺纳米碳酸钙(NC)混凝土的劈裂抗拉性能,进行了不同NC掺量(0%、0.5%、1.0%、1.5%、2.0%和3.0%)混凝土的高温试验,对分别采用自然冷却和喷水冷却方式后的NC混凝土进行了加载试验.分析了温度、NC掺量及冷却方式等对混凝土劈裂抗拉强度的影响.结果表明:随着受热温度的增加,NC混凝土的劈裂抗拉强度逐渐降低.在混凝土中添加适量的NC可以改善混凝土高温后的劈裂抗拉性能.不同的冷却方式对NC混凝土劈裂抗拉强度有不同的影响:高温(尤其是400℃以上)后采用喷水冷却的混凝土静置两周后,其劈裂抗拉强度均高于采用自然冷却后的劈裂抗拉强度.同时,800℃后,自然冷却的NC混凝土试块在室内放置两周后多数发生自行坍塌情况,几乎完全丧失强度.研究结果可为进一步开展纳米混凝土高温后的其它力学性能和耐久性能提供参考.     

高温对高强度水泥砂浆强度影响的试验研究

对高强度等级水泥砂浆在经历不同温度（150℃、300℃、450℃、600℃）、不同冷却方式（喷水与自然冷却）后的力学性能进行了试验,研究了高温对高强度水泥砂浆力学性能的影响规律。结果表明：高强度等级水泥砂浆抗压强度随受热温度的升高而逐渐降低,当温度在300℃以下时,强度下降较静;温度在450℃以上时,强度下降明显。冷却方式对砂浆抗压强度退化影响较为明显,相同受火温度,喷水冷却后的砂浆强度低于自然冷却后的砂浆强度。并得出不同冷却方式、不同强度等级水泥砂浆高温后抗压强度退化的公式。     

化学锚栓的高温力学性能试验

通过对有机化学锚栓和无机化学锚栓进行不同火场温度、冷却方式及静置时间条件下的实验室对比试验,研究了有机化学锚栓与无机化学锚栓的高温力学性能特性。研究结果表明:火灾高温作用后,化学锚栓的抗拔承载力整体呈降低趋势;随着温度逐渐升高,有机化学锚栓的抗拔承载力大幅度降低,无机化学锚栓的抗拔承载力先降低,后小幅回升,再大幅度降低;有机化学锚栓和无机化学锚栓的工作极限温度分别为170℃和450℃,耐火极限温度分别为300℃和700℃。     

带压制锚具的高钒镀层拉索火灾后的力学性能（英文）

高钒镀层拉索作为一种主要受力构件越来越广泛地应用于预应力钢结构当中。若火灾后结构整体未发生倒塌,则需要对其中拉索性能的改变进行准确评估以确保安全。本文对带有工程中常用的压制锚具的高钒拉索火灾后力学性能进行了试验研究。对经历13个预定温度后的拉索试件进行拉伸试验,考虑了空气自然冷却和消防喷水冷却两种冷却方式。试验得到了试件的荷载-位移曲线、初始刚度、承载力和变形能力等力学性能,并讨论了锚具的影响。拉索试件的力学性能在经历超过400℃高温后明显改变,此外不同冷却方式的影响也非常显著:经过消防喷水冷却的拉索试件在经历700℃高温后几乎丧失了全部承载力和变形能力。最后提出了计算带压制锚具的高钒拉索火灾后力学性能的经验公式,并考虑不同冷却方式影响。     

基于有限元的无保护层钢结构柱抗火分析

采用大型有限元软件M SC.M ARC.M en tat,对具有轴向约束且无保护层的钢结构柱进行了非线性有限元分析,研究了不同轴向约束对钢结构柱抗火能力的影响,给出了典型约束钢结构柱的有限元网格划分和受压后的变形图,以及不同温度、不同约束刚度情况下的荷载-位移曲线,有限元数值模拟结果与试验进行对比,吻合较好.研究表明:室温下,轴向约束有利于提高柱子的极限承载能力,但在高温情况下,约束刚度的大小对柱子的抗火承载力却具有负面影响,轴向约束的提高降低了高温下柱子的极限承载力,并降低了柱子的极限温度承载力;在温度达到450℃之前,由于钢材的弹性模量改变与构件热膨胀而导致承载力的降低,温度超过450℃之后,弹性模量与屈服极限的折减,以及构件热膨胀所导致的约束反力共同作用使得构件更早失效.     

高温下与高温后Q550D高强钢材料力学性能试验

高强钢具有强度高、韧性好、可焊性优良等优点,其在土木工程中的应用越来越广泛.高强钢在火灾下的力学性能是钢结构抗火设计的重要影响因素.为获取高温下与高温后Q550D高强钢材料的力学性能,基于稳态试验方法,对Q550D高强钢开展了拉伸试验,考察了不同冷却方式(自然冷却与浸水冷却)与过火温度对Q550D高强钢力学性能的影响,获取了不同温度工况下Q550D高强钢的应力-应变曲线和高温下与高温后各项力学性能参数指标(弹性模量、屈服强度、抗拉强度和极限伸长率)的折减系数,并将试验结果与已有规范和文献结果进行了对比分析.结果表明:高温下Q550D高强钢的弹性模量、屈服强度、抗拉强度随着试验温度的升高而逐渐下降,其折减系数均低于各国规范的取值;当温度超过400℃时,高温下Q550D高强钢的弹性模量、屈服强度和抗拉强度下降明显,当温度超过700℃时,3个力学性能指标均接近于零;不同冷却方式与过火温度对Q550D高强钢的弹性模量影响不大;当温度低于600℃时,高温冷却后Q550D高强钢的屈服强度和抗拉强度的折减并不明显,当温度超过600℃时,屈服强度和抗拉强度显著下降,且自然冷却方式下的下降程度更大;高强钢与普通钢高温冷却后的屈服强度与抗拉强度存在较大差别.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the