粉煤灰掺量对C45自密实混凝土强度的影响

为了研究粉煤灰对自密实混凝土抗压性能的影响,配置C45自密实混凝土,水灰比为0.35,粉煤灰掺入量为0%~40%。研究发现,粉煤灰的掺入对混凝土抗压强度影响较大,随着粉煤灰的增加,强度呈现先增加后减小的趋势;随着龄期增长,混凝土抗压强度呈增长趋势,且粉煤灰掺入量为25%时抗压强度最优,达到60.7MPa;得到了C45自密实混凝土的龄期强度模型。

冷弯薄壁型钢组合截面受压构件受力性能与设计方法研究

冷弯薄壁型钢截面高效,在建筑钢结构领域得到广泛应用,随着冷弯型钢房屋结构布局、建筑层数等的变化,拼合截面构件的应用也越来越多。文中首先简要介绍了北美和我国关于冷弯薄壁型钢组合截面受压构件的设计方法,然后综述了国内外在冷弯薄壁型钢拼合截面受压构件的受力性能和设计方法方面的的研究成果,最后在分析的基础上提出冷弯薄壁型钢组合截面受压构件亟需解决的相关研究问题。

Vibrating Liquefaction Experiment and Mechanism Study in Saturated Granular Media

By the vibrating liquefaction experiment of tailings and fine-ores of iron, it is observed and noted that the change of pore water pressure when the vibrating liquefaction takes place. Based on relevant suppositions, the equation of wave propagation in saturated granular media is obtained. This paper postulates the potential vector equation and the velocity expression of three kinds of body waves under normal conditions. Utilizing the wave theory and the experimental results, the influence of three body waves on pore water pressure and granules has been analyzed in detail. This revealed the rapid increment mechanism of pore water pressure and the wave mechanism of vibrating liquefaction.