钢筋混凝土梁柱加固方法及承载力计算

危房加固的方法很多,但首先是进行房屋安全鉴定,检查、检测出房屋的破损情况,并查明原因。根据破损原因和破损情况,选取适宜的加固方法,以达到既经济实用,又能保证房屋使用安全的目的。文章主要介绍了粘钢法加固钢筋混凝土梁、增大截面法加固钢筋混凝土柱的加固特点及承载力计算,为今后采用该加固方法加固钢筋混凝土梁柱提供理论依据。     

轻型淤煤装载机提装部链轮的设计

轻型淤煤装载机是煤矿井下水仓清理专用设备,提装部的主、被动链轮组件是该装载机的重要组成部分,它们不但要承受较大的载荷,且密封要求较高,介绍了一种很好的解决问题的方法。     

复合载荷下裂纹体的弹塑性断裂行为的电镜原位观察

应用电原位拉伸的方法观察了解合金ＬＹ１２在不同（Ｉ＋Ⅱ）复合型下裂纹尖端的塑性变形和断裂过程。结果表明，复合载荷作用下裂纹尖端的变形是钝一锐化变形模式。裂纹的断裂发生了钝化区，断裂方位与最大应力三轴性水平的分布方位一致。不同复合型下的断裂遵循等太孔洞损伤机制，最大周向拉应力是铝合金复合型断裂的力学控制因素。随Ⅱ型分量增加，ＬＹ１２启裂ＣＯＤ值增加。     

运矿列车装车称重及控制系统设计

介绍一种矿石列车料仓放料装车时，自动检测重量及装车控制系统的设计，该系统检测精度高，安装工期短，操作、使用、维护方便，取得很好的实际应用效果。     

影响BDS系列安全乳化炸药性能的因素分析

从炸药原料、组分配比、生产工艺控制条件和装药车的计量系统等方面分析了影响ＢＤＳ系列乳化炸药性能的因素，针对德兴铜矿炸药的生产工艺特点，提出了改善ＢＤＳ系列乳化炸药性能的几项措施。     

便携式纺织路面织物的结构及其承载能力

摘要： 由于车辆在地基条件差,不易通行的软土路面上行驶时,容易出现履带和轮式车辆淤陷,无法机动的现象,给车辆的通行带来很大的不便,在军用方面更为突出。本问介绍一种用于软土路面,可供重载车辆顺利通行的便携、快速通道,即纺织结构路面材料。通过织物的组织,分析便携式纺织路面材料结构的形成原因。设计两种不同结构的织物进行测试,验证纺织路面的特殊结构可提高织物的承载能力。通过测试结果得出,便携式纺织路面织物的结构具有更好的承载能力;设计四种不同纬密的纺织路面进行测试,验证纬密的增加可提高织物的承载力。通过测试结果得出,便携式纺织路面织物的承载性能随着织物纬密的增加而提高。     

Insitu upgradation of biocrude vapor generated from non-edible oil cake's hydrothermal conversion over aluminated mesoporous catalysts

In this work, biocrude vapors generated from hydrothermal conversion of Pongammia pinnata cake using high pressure reactor at 400 °C and 25 kg/cm² were upgraded over three mesoporous catalyst namely SBA-15, KIT-6 and FDU-12. The catalysts were synthesized, aluminated and characterized using X-Ray Diffraction, N₂ adsorption-desorption, SEM techniques. A decrease in the surface area was observed on all three mesoporous catalyst after alumina loading with negligible effect on the pore diameter. Purely siliceous catalysts were found to give negligible effect on the yield of different product phases. Alumina supported SBA-15 (SAR 30) was observed as the suitable catalyst as compared to Al/FDU-12 (SAR 30) and Al/KIT-6 (SAR 30) for maximizing the biocrude yield with low heavy hydrocarbons (46.3 ± 2.2%), polyaromatic hydrocarbons (17.1%) and acidic compounds (9.1%) content. Therefore series of SBA-15 were synthesized by varying silicon to alumina ratio between 20 and 50 for maximizing hydrocarbons with boiling cut fractions between 195 and 317 °C corresponding to gasoline range hydrocarbons. Al/SBA-15(SAR 40) was found to give highest biocrude yield (∼34.8%) with highest selectivity towards gasoline fraction (23.7 ± 1.9%). GC/MS analysis was used to confirm the presence of aliphatic and aromatics. Highest asphaltene content was observed with Al/SBA-15 (SAR 50).     

Wind-induced failure of wind turbines

Models of loading and structural behaviour for use in lifetime prediction of propeller type wind turbines are discussed. The emphasis is on wind-induced loads, which are separated into periodic dynamic loads due to rotation in the spatially nonuniform mean windfield, and stationary stochastic loads due to wind turbulence. Turbulence is represented by auto- and cross-spectra of the turbulent wind speed fluctuations. The spectra are derived, however, for the turbulence as seen from points of a rotating wind turbine blade, which significantly changes the shape of the spectra. Structural response is calculated in the frequency domain and the stress responses appear as a combined periodic and stochastic signal. A fatigue model and a simple approach to extreme response calculations have been derived, which take into account both the periodic and the stochastic parts of the stress response. Assuming that failure occurs either by a slow accumulation of damage or by a sudden exceedence of a critical value for the stresses, the models can be used in the design phase when predicting the lifetime and assessing the safety of a wind-turbine structure. Finally, results from applying the model are presented and compared with available measured data.     

世纪莲体育中心动力特性及反应谱分析

以佛山市世纪莲体育中心大跨度轮辐式张拉索膜结构为研究对象,采用ANSYS程序建立有限元模型,分析其动力特性,并用振型分解反应谱法计算地震作用下结构的受力性能.研究结果表明:结构自振频率较低,频谱集中,频率跳跃现象不明显;结构以屋盖的竖向振动为主,具有较好的抗侧刚度和抗扭刚度;反应谱分析时,为保证各方向的模态质量参与系数...     

Analysis of the effect of UV radiation on the recovery properties of pile carpet after static loading through analytical and viscoelastic modeling

Different combinations of spring and dashpot systems are usually considered to model the mechanical behavior of textile materials. In this work, Jeffery’s mechanical model, which is a combination of spring and dashpot components, was used to model the recovery behavior of the pile carpet after static loading. The carpet samples were exposed to different levels of UV radiation. The short-term static loading was applied to the samples. The recovery response or thickness vs. time was then measured. By analyzing this model and using the best curve fitting based on the least square method, the viscoelastic parameters in each UV exposure time were calculated. Four attributes of compression were then studied. The results showed that the thickness loss and the maximum compression under a constant load were mainly dominated by the deterioration of the dashpot elements (Plastic part of deformation). The thickness loss and the maximum compression were both higher at longer UV exposure times. The thickness loss showed a good linear correlation with the inverse of the first dashpot constant, 1/η₁. In contrast, the speed of recovery and the potential stored energy were mainly dominated by the parameters of the Voigt–Kelvin body, i.e. the elastic part of the compression.