钢筋混凝土梁和柱性能界限状态及其变形限值

根据以受弯为主的钢筋混凝土梁、柱的地震破坏过程提出了各性能水平和性能界限状态的划分标准,并建立了对应于各性能界限状态的变形计算方法。通过对梁、柱截面的弯矩-曲率分析,分别建立了梁、柱截面受压区高度的计算方法。利用对美国太平洋地震工程研究中心建立的钢筋混凝土柱试验数据库的统计分析和钢筋混凝土受弯构件的塑性铰理论,提出了柱在各性能界限状态时截面压区边缘混凝土的应变限值计算方法。通过混凝土受压应变和钢筋受拉应变的限值得到钢筋混凝土梁、柱的变形限值。研究结果可为钢筋混凝土结构基于位移的抗震设计和抗震性能评价提供依据。     

张弦梁屋架对排架柱的受力影响分析

张弦梁结构作为屋架应用于排架厂房中,对排架柱的受力产生影响.通过数值仿真试验方法,分析了张弦梁屋架对排架柱的支撑刚度,进而得到结论.在排架结构的内力分析中,张弦梁屋架自身符合轴向拉压刚度无限大的假定,但屋架支座形式对排架柱的受力影响较大,使用滑动支座时的排架柱内力比使用铰接支座时增加约8%.     

天津津塔超高层钢管柱混凝土顶升浇筑技术

天津津塔工程采用带纯钢板剪力墙的钢管组合柱结构体系,为保证混凝土质量,采用顶升混凝土浇筑法.针对津塔工程混凝土强度高、黏度大、泵送距离长、坍落度损失大等特点,提出了控制混凝土水胶比、掺加适量膨胀剂等技术措施.另外详细介绍了顶升口设置、钢管柱预留孔设置、混凝土泵送、钢管柱内混凝土密实性和强度检验等.指出钢管混凝土施工过程中,应重视泵管检查、泵送压力观察、防雨雪及防冻.     

贵阳奥体中心主体育场异形柱施工技术

贵阳奥体中心主体育场南北看台有36根混凝土弧形柱,西看台有20根钢结构Y形柱和10根混凝土Y形柱.由于施工荷载大,仅靠模板体系承担施工荷载困难.经过计算,决定通过合理分段,依靠Y形柱和弧形柱自身的承载能力承担施工荷载.弧形柱分3步施工,Y形柱分5步施工.为保证弧形柱和Y形柱的施工质量和清水混凝土效果,采用定型钢模板施工,工厂制作,现场拼装.主要介绍了弧形柱和Y形柱的模板体系及支撑体系的选择以及施工技术.     

Impact of retention on trans‐column velocity biases in packed columns

The heights equivalent to a theoretical plate of a weakly and strongly retained compounds were measured on two packed columns having different average mesopore sizes. The measurements were carried out in two different cases, with access to the mesopores by the sample molecules blocked (filled with n‐nonane) or not. The experimental results demonstrate that the eddy dispersion terms of both columns are significantly smaller for porous than for nonporous particles. Two simultaneous phenomena explain this observation. First, packed columns are radially heterogeneous which causes significant trans‐column velocity biases warping the bands. Second, radial dispersion contributes to mass transfer across the column, relaxing the radial concentration gradients that are caused by these velocity biases. The impact of these biases is minimized when the pores of the particles are not blocked; it decreases with increasing residence time and radial dispersion coefficient of the solutes. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Localized electrochemical deposition of micrometer copper columns by pulse plating

Micrometer copper column fabrication by localized electrochemical deposition (LECD) was investigated in this study. To obtain columns with uniform diameter, compact structure and a smooth surface, LECD conducted in pulse current (PC) mode was better than that conducted in direct current (DC) mode. A micro-reference electrode was used to monitor the potential at the LECD site. Measurement of this potential permitted estimation of the local copper ion concentration resulting from their dynamic consumption by electrochemical reduction and their supply by mass transport. The electroplating current was measured in order to evaluate the rate of electrochemical reduction. The mass-transfer rate of copper ions was estimated using a theoretical calculation based on diffusion. The surface morphology and internal structure were significantly affected by this local concentration, which was in turn governed by the electrical voltage and the duty cycle employed. The mechanism for LECD conducted in PC mode is discussed.     

酸性水汽提装置长周期运转的影响因素

根据酸性水汽提装置技术改造及投产建设实践,分析了酸性水汽提装置工艺技术特点,提出保持装置长周期平稳运转应注重汽提工艺的选择、酸性水预处理、汽提塔操作、设备及管道防腐等4个主要影响因素。     

大港减压渣油超临界萃取物的柱层析分离及GC/MS分析

在大港减压渣油超临界萃取物(DVR SFEF)的GC/MS分析检测中,除了大港减渣1级萃取分F1以外,在其他级分中分析检测出的物种和数量均较少,特别是DVR SFEF 10~SFEF 17的检测结果很不理想。故通过层析柱对DVR SFEF按照标准分析方法进行分离,可以得到饱和分、芳香分、胶质和沥青质在DVR SFEF中的分布规律,以及DVR SFEF所含饱和分、芳香分、胶质和沥青质中链烃、环烷烃和芳烃的含量的变化规律;还检测出了具有高附加值的稀有物质。     

方钢管约束钢筋高强混凝土超短柱抗震性能试验研究

本文进行3个剪跨比为1.5的方钢管约束钢筋高强混凝土超短柱和1个钢筋混凝土对比试件的试验研究,试验中的主要参数为轴压比(0.35,0.45和0.55)。试验结果表明,由于钢管对核心高强混凝土的约束作用和钢管的抗剪作用,方钢管约束钢筋混凝土超短柱的抗剪承载力、延性、变形能力和耗能性能明显高于钢筋混凝土超短柱。轴压为0.35的方钢管约束钢筋混凝土超短柱的破坏模式为弯曲破坏,而轴压比为0.45和0.55的方钢管约束钢筋混凝土超短柱的破坏模式为剪切破坏。随轴压比的提高,方钢管约束钢筋混凝土超短柱的抗剪承载力提高,但延性系数和极限变形能力降低。对钢管的弹塑性应力分析结果表明,水平荷载施加过程中,发生弯曲破坏试件的钢管不屈服,而发生剪切破坏试件的钢管可能在下降段屈服。根据试验结果和钢管应力分析结果建立方钢管约束钢筋混凝土柱的抗剪承载力公式,提出设计建议,可为工程实践提供参考。     

嘉兴垃圾填埋场渗滤液的土柱淋滤实验研究

通过室内淋滤实验分析垃圾渗滤液-水-岩相互作用过程。实验发现Cl-的保守性是相对的,其中在粉砂土中Cl-存在吸附解吸现象,平衡浓度为4446mg/L时,分配系数Kd=0.18L/kg,而在壤土(亚粘土)中Cl-保持保守。SO42-和F-积极参与水岩相互作用,粉砂土和壤土对SO42-和F-均有较强的吸附作用。阴离子交换作用的结果使大量的NO 3-从粉砂土中解吸出来。