聚羧酸系高性能减水剂的研究现状与发展方向

聚羧酸系高性能减水剂是减水剂的新品种,具有很多良好的使用性能。介绍了聚羧酸系高性能效减水剂国内外研究现状、目前3种不同合成方法的研究现状及优缺点、作用机理的研究,提出一些亟待深入研究的问题及聚羧酸系高性能减水剂今后的研究方向。     

浅谈聚羧酸系高性能减水剂的应用

聚羧酸系高性能减水剂虽然使混凝土在减水、保坍、增强、低收缩及环保等方面具有了优良的性能。但是，施工实践表明，该种减水剂存在比高效减水剂更难掌控的应用技术问题。特别是聚羧酸系高性能减水剂对混凝土原材料的适应性问题，对用水量敏感性问题以及滞后泌水等新问题，还需要系统研究     

高效减水剂在高性能混凝土中的应用

简要叙述了高效减水剂的作用机理及其品种。通过工程实例说明高效减水剂在高性能混凝土中所起的作用和经济效果,提出了进一步研究开发用于高性能混凝土的新一代减水剂的建议。     

高性能减水剂的研究现状与发展方向

概述了国内高性能减水剂的研究进程和现状,从化学结构的角度对高性能减水剂进行了分类并介绍其特征,从分子设计的观点出发,提出减水剂高性能化的途径和理论基础,指出单环芳烃型和聚羧酸系是高性能减水剂的研究方向,并介绍其研究内容。     

高性能混凝土现场生产配制研究

本文结合京九铁路后张梁高性能混凝土现场生产配制开展试验研究和应用，就高性能混凝土集料选用、配合比设计、水泥与高效减水剂相容性、以及高效减水剂对高性能混凝土坍落度损失的影响、假凝现象的防止等作了理论性阐述，并分析了高效减水剂、水灰比、坍落度、水泥与粗骨料用量、混凝土弹性模量在高性能混凝土中的机理作用。     

聚羧酸系高效减水剂的研究现状与展望

聚羧酸系高性能减水剂是一种新型的高效减水剂,具有很多良好的性能.文章结合国内外资料综述了聚羧酸系高性能减水剂的作用机理、国内外研究及合成方法,总结了当前研究与应用中存在的问题,并对未来发展方向进行了展望.     

JY-PCA型聚羧酸系高性能减水剂合成与性能研究

介绍了JY-PCA型聚羧酸系高性能减水剂的合成,重点研究了该减水剂的性能。研究表明,JY-PCA型聚羧酸系高性能减水剂具有良好的减水效果与保坍性能,与传统萘系减水剂相比,聚羧酸系高性能减水剂可以明显改善混凝土的收缩性能。     

利用聚羧酸系高效减水剂配制C100高性能混凝土的试验研究

介绍了新近国际上开发出的第Ⅲ代高效减水剂－聚羧酸类减水剂的特点，作用机理之后，指出了其分子设计与合成的方向，利用聚羧酸类减水剂进行了C100高性能混凝土验证性试验研究表明：在不掺加硅灰的条件下利用聚羧酸类减水剂可实现C100高性能混凝土，认真探索聚羧酸类高效减水剂的快速结硬机理以及如何降低混凝土拌合物粘度是推广应用聚羟酸高效减水剂的关键性技术问题。     

ZS系列反应性高性能减水剂的研究

利用改进分子结构、单元种类、官能团比例及对官能团改性等方法，研制出了多羧酸系ＺＳ、ＺＳＦ系列反应性高分子减水剂，对减水剂合理掺量、高性能砂浆和砼等进行了试验研究，证明掺入新的高效减水剂后，砼及砂浆具有减水率高、流动性好、力学性能优良等特点。     

聚羧酸系高性能减水剂在桥梁工程混凝土中应用的对比试验研究

本文结合正在建设中的厦门快速公交路线工程，通过对比试验，探讨了用萘磺酸盐系和聚羧酸系高效减水剂配制的混凝土的性能，结果表明聚羧酸系高性能减水剂用于C50及以上高强、高性能混凝土是其应用发展的重要方向，这方面是奈磺酸盐系高效减水剂所无法比拟的。     

复合桩基工作性状的非线性分析

运用有限元与无限元相结合的手段,分别以非线性模型和线性模型描述桩间土体和桩周土体的变形特征,通过计算结果的分析,揭示了复合桩基的工作原理,总结了复合桩基的基本特征,研究了一些主要因素对复合桩基工作性状的影响,指出了复合桩基应用中需要注意的问题.     

An experimental study on delamination of FRP plates bonded to concrete

Results of an experimental campaign on FRP–concrete delamination are presented. Specimens with different bonded lengths and plate widths have been tested. Strain gauges along the FRP plate have been used to measure longitudinal strains. For long bonded lengths, progressive debonding along the specimens has been followed. Starting from experimental data, average shear stress–slips data have been computed. By post-processing these data, non-linear interface laws for two different plate widths have been calibrated. Increase of maximum shear stress with decreasing plate width has been observed, whereas no significant plate width effect on fracture energy and delamination force has been found. Experimental tests have been simulated by adopting a numerical bond-slip model and the above mentioned non-linear law for the FRP–concrete interface. Numerical results in good agreement with experimental results have been obtained, both at low and very high loading levels.     

Thermodynamic analysis of designed and fabricated shell- and tube-type heat exchanger by DSTHE software: Kern method

In this research work, shell- and tube-type heat exchanger has been designed by Kern method. To eliminate design problems, computer software (DSTHE software) has been developed. All design parameters have been calculated by this method with the help of DSTHE software such as number of tubes, shell diameter, pipe pitch and pitch ratio. And then velocity of the tube side fluid, convective heat transfer coefficients for tube and shell side fluids and overall heat transfer coefficient have been calculated. By developed DSTHE software, tube side and shell side fluids pressure drops, entropy generation and entransy dissipation have also been found. Shell- and tube-type heat exchanger has been fabricated with calculated parameters. At various operating conditions, a number of experiments have been performed. For each condition, entropy generation analysis, entransy dissipation analysis and entransy-based thermal resistance analysis have been done. Maximum value of effectiveness, minimum values of entropy generation, entransy dissipation and entransy-based thermal resistance have been found and that actual operating conditions have been identified.     

Short- and long-term analytical solutions for composite beams with partial interaction and shear-lag effects

This paper presents an analytical model for the short- and long-term analysis of composite steel-concrete beams with partial shear interaction and accounting for shear-lag effects. The material properties of the concrete have been assumed to be time-dependent and have been modelled by means of the algebraic methods while the remaining materials forming the cross-section have been supposed to behave in a linear-elastic manner. The global balance condition of the problem has been obtained by means of the principle of virtual work and, integrating this by parts, the governing system of differential equations and corresponding boundary conditions have been determined. Analytical expressions for both short- and long-term solutions have been derived and, to outline their ease of use, a number of case studies relevant for bridge applications have been proposed.     

我国建筑抗震技术的发展水平与成就

邢台地震以来，我国在抗震技术的各个领域都得了长足的进步。抗震基础理论的研究和应用已处于世界前沿的位置，并制定了相应的标准规范。多层和高层建筑的抗震设计有了很大发展，还进行了２亿ｍ＾２建筑的抗震加固工作。     

水工混凝土抗软水接触性溶蚀试验研究

本文通过试验研究了水工混凝土的接触溶蚀性能。论述了混凝土外加剂、环境水化学成分对混凝土接触溶蚀性能的影响，通过试验结果估算了混凝土的溶蚀耐久性，分析了软水对混凝土的溶蚀机理，提出了防止和减缓混凝土溶蚀破坏的有效措施。     

洁净室流场数值模拟的研究进展

对洁净室的应用和发展进行了回顾，分析了洁净室的流场，介绍了数值模拟方面常用的几种模型及国内外在洁净室模拟方面取得的成果，列举了常用的CFD软件，分析了国内研究所存在的问题。     

装配式混凝土框架结构节点构造方法简介

对装配预制式混凝土框架结构承重构件的连接进行分类,介绍了连接在设计和施工阶段中应注意的事项,同时介绍了几种梁柱连接的构造形式及特点。     

轨道交通9号线下穿铁路工程风险及对策研究

结合上海市轨道交通9号线一期工程R413标段九亭站-七宝站区间盾构隧道下穿沪杭铁路工程,对工程可能出现的风险进行分析,并作出相应对策.针对可能出现的轨道过大变形,提出对轨下盾构穿越区进行全断面分区注浆及旋喷加固.对重要管线采取了针对性的加固保护措施,通过加固形成隔离带以控制其变形,同时设置卸压孔以防止高压注浆引起土体过大位移.结果表明,轨道变形及管线移位都得到了有效的控制,地表隆沉在控制范围内,加固区轨下动应力得到有效的降低.     

Modelling anaerobic biomass growth kinetics with a substrate threshold concentration

Many bacteria have been observed to stop growing below a certain substrate threshold concentration. In this study, a modification of the Monod kinetics expression has been proposed to take into account this substrate threshold concentration observed in bacterial growth. Besides the threshold concentration no additional parameters have been added to the kinetic expression and so, only the substrate threshold concentration and the half-saturation constant have to be estimated for model calibration purposes. Furthermore, for parameter estimation purposes, practical identifiability of this new function has been studied and the results have been satisfactory. The new model has been applied, as an example, to a simple anaerobic model to simulate the competition for hydrogen between sulphate reducers and methanogens in a thermophilic methanol-fed bioreactor. Oscillatory behaviour and mathematical instabilities have been avoided by using the proposed model. Parameter sensitivities have also been calculated along the simulation period in order to investigate the importance of hydrogen threshold concentration parameters.