异形柱框架体系设计轴压比限值研究

从异形柱大、小偏心受压界限破坏条件出发,导出了钢筋混凝土异形柱轴压比限值的计算公式,分析了等刚度矩形截面柱轴压比限值存在的问题,并对异形柱轴压比设计值提出了建议。     

沥青混合料配合比设计方法研究

介绍了沥青混合料的原材料选择应考虑的因素及试验要求，论述了计算机配合比设计方法，探讨了沥青路面的施工压实标准，以使沥青混合料的各项技术指标满足规范要求。     

多点交替进水五箱一体式工艺污泥回流比研究

介绍了多点交替进水五箱一体式工艺的流程与特点，研究了不同污泥回流比下反应器对氮、磷的去除效果。结果表明，在运行周期为16h、污泥回流比为55％的条件下，反应器对COD、BOD5、NH4^＋-N、TN、TP的去除率分别达到78％、84％、86％、70％、89％。此外，建立了反应池内污泥浓度的分布模型，并计算得出不同回流比下污泥浓度的变化规律，通过对计算值与试验检测结果的比较，提出了后期工艺的改进方向。     

单层钢结构厂房X型柱问支撑问题的探讨

通过对投入使用后的某工程X型柱间支撑出现问题的原因进行分析，提出了单层钢结构厂房X型枉间支撑设计和施工时应注意的一些问题，并给出了有关X型柱间支撑设计和施工方面的一些建议，供类似工程设计和施工时参考。     

粉煤灰在混凝土中的应用技术

混凝土技术的发展,包括水泥活性、细度提高,以及化学外加剂,尤其是高效减水剂的广泛应用,混凝土水胶比可以大幅度降低,使粉煤灰在混凝土中的作用发生变化,充分认识这种变化带来的影响,推进粉煤灰在混凝土中大掺量地应用,可以改善混凝土的性能、节约水泥,有利于环境保护、节能,促进混凝土技术的可持续发展。     

Experimental investigation on built-up columns

This study presents a direct experimental verification of the AISC-LRFD slenderness ratio formulas for built-up compression members. Comparisons of slenderness ratios as specified in various design codes including the AISC-ASD, the AISC-LRFD, the AS-4100 and the CSA S16-01, are also provided. Test results concluded from this study show that the 1999 LRFD formulas generally result in conservative design strengths. However, the 2005 LRFD yields slightly higher strength due to the use of a higher resistance factor of 0.9 instead of 0.85. The design strengths determined based on the slenderness ratio formulas of the Australian Code (AS-4100) are even more conservative. For back-to-back snug-tight bolted sections, the Canadian Code (CSA S16-01) gives virtually the same design outcome as the LRFD. While for back-to-back welded sections, the CSA S16-01 tends to yield a less conservative design.     

混凝土冻害的破坏机理及防治措施

通过对混凝土的冻害破坏机理和破坏特征的探讨,对影响混凝土抗冻性能的主要因素进行了阐述,并提出改善混凝土抗冻性能的措施,以提高混凝土的耐久性。     

单层柱面网壳结构常遇三维地震作用下的地震响应分析

地震内力系数法是一种适用于空间网格结构的简洁有效的抗震设计方法,但应用于单层网壳结构时需要改进。根据单层网壳结构的受力特点,考虑弯矩影响,修正了传统地震内力系数的定义,并选取大量单层柱面网壳算例进行了常遇三维地震作用下的时程分析,观察其杆件地震内力系数取值随矢宽比、长宽比、杆件截面等参数的变化规律,发现在文中研究范围内,单层柱面网壳结构地震内力系数取值随长宽比增大有逐渐增大的趋势,随矢宽比的增大有逐渐减小的趋势。在大量统计分析的基础上,归纳出可供实际工程设计参考的地震内力系数建议取值。     

丁苯乳液对水泥砂浆吸水率和碳化深度的影响及其机理

研究了丁苯乳液对水泥砂浆吸水率及碳化深度的影响,并提出了吸水率、碳化深度的多因素预测模型.测定了丁苯乳液改性砂浆的微观孔结构参数,包括开口、闭口孔隙率大小及总孔隙率、孔径分布及特征孔径;以扫描电镜的测试结果表征了丁苯乳液改性砂浆的微观形貌特征;根据测试结果,分析了丁苯乳液对砂浆吸水率及碳化深度的作用机理.研究结果表明,丁苯乳液的掺入明显降低了砂浆的吸水率以及碳化深度.当丁苯乳液掺量超过3%(丁苯乳液总质量与水泥质量的百分比)后,水泥石中20 nm以下的小孔数量明显增多,而50 nm以上大孔数量则有所减少,平均孔径、最可几孔径以及中值孔径都有较大幅度的下降;当丁苯乳液掺量超过6%之后,改性砂浆的开口孔隙率显著降低,闭口孔隙率增多,但总孔隙率变化不大.     

Microgrinding of deep micro grooves with high table reversal speed

Recent progress in the miniaturization of electronic items introduces manufacturing challenges for achieving both better surface integrity and high throughput. Controlled thermal interaction processes physically vaporize the material for producing the miniature components but the poor surface and sub-surface characteristics introduce a niche for thermo-mechanical processes, particularly microgrinding. Prior microgrinding attempts have focussed on axi-symmetrical components of hard-brittle materials. For non-axi-symmetrical, high-aspect ratio miniature components, edge chipping was encountered. This paper reports a new grinding method that uses “high table reversal speeds” for reducing the “grit cut load” and hence facilitates the microgrinding process. An arrangement that functions on the principles of four bar linkage with a sliding and rotating pair was devised. This arrangement was designed to reciprocate between 300–1000 strokes/min for a stroke length of 10–70 mm. As a result the table feed rate range was increased from the conventional 300–20 000 mm/min to 5000–55 000 mm/min.Process characterization of the new grinding method was observed for hard-brittle materials. A physical model was developed which links the process parameters with appropriate boundary conditions and the model was verified experimentally. The experimental model was used to explain the mechanism of grinding while employing high table reversal speeds. Process characterization includes grinding force, grinding-ratio, grinding wheel topography, surface finish and SEM study. Also, the process was applied to produce mold-insert which in turn was used for molding the micro-mechanical cantilever sensor parts. Deep slots of size: 1.2×0.1×1.5 mm with an aspect ratio of 15 was successfully produced with this method. The new grinding device and method promote microgrinding through integration to an existing grinder and therefore reduces the additional cost on the capital resources.