火灾场钢筋混凝土简支梁抗弯性能分析

通过对火灾中钢筋混凝土简支梁截面温度场和材料热力学性能分析,将混凝土分为弹性区和塑性区来分别计算其强度,建立了火灾场简支梁截面内混凝土应力和梁极限抗弯承载力的计算公式,通过具体算例分析了钢筋混凝土简支梁截面温度场和极限承载力的变化规律和原因。     

基于MIMO的信号检测技术在宽带数据链中的应用

分析了多输入多输出系统中空分复用和空时分组码的解码算法,提出了一种空分复用和空时分组码相结合的方案,探讨了这种方案的解码算法并对该算法进行了仿真验证.结果表明,这种方案的BER性能在高信噪比时要好于其它方案,因而可以应用到需要高传输速率以及高链路可靠性的宽带数据链中.     

全CFRP筋混凝土柱低周反复荷载试验研究

考虑轴压比、剪跨比和配箍形式的影响,对6根全CFRP筋混凝土柱进行低周反复荷载试验,通过分析滞回曲线、骨架曲线、位移延性系数和耗能能力等特征,研究CFRP筋混凝土柱的抗震性能。试验结果表明:CFRP筋混凝土柱具有较强承载能力和变形能力;轴压比和剪跨比是影响试件抗震性能的主要因素,轴压比越小,试件的变形和耗能能力越强,刚度退化越平缓,剪跨比越大,试件的变形能力越强;通用屈服弯矩法计算得到的延性系数能够较好反映CFRP筋混凝土柱的延性,轴压比越小、剪跨比越大,试件的延性越好;新型螺旋式矩形箍筋在试件延性及耗能方面表现良好,可以应用于工程实际。     

Resistance of grid steel-tube-confined concrete targets against projectile impact: Experimental investigation and analytical engineering model

Steel-tube-confined concrete (STCC) targets are provided with excellent anti-penetration performance over semi-infinite concrete (SIC) targets since the steel tube imposes passive restraint on the in-filled concrete during the penetration process. Grid STCC system with square steel tubes is a potential solution to protective structures. In this paper, experiments of 9-cell grid STCC targets penetrated by 12.7 mm Armor Piercing Projectile (APP) were performed. The influence of side length and thickness of steel tube, steel ratio and impact velocity on anti-penetration performance were taken into account. Additionally, single-cell square STCC targets were also designed and tested for comparison with the 9-cell grid STCC targets. Damage modes and parameters of the tested targets were measured and discussed. Moreover, the stiffness of radial confinement of grid STCC targets is achieved according to the elastic solution of infinite cylindrical shell in Winkler medium. Furthermore, the penetration resistance and depth of penetration (DOP) for grid STCC targets are obtained on the basis of the dynamic finite spherical cavity-expansion (FSCE) models including radial confinement effect. It is shown that the 9-cell grid STCC targets with optimal dimension match of thickness and side length of steel tube can reduce the DOP by about 17 % and 23 % in comparison with the SIC targets and single-cell square STCC targets, respectively, due to both the confinement of square steel tube to concrete in the impacted cell and the additional confinement of the surrounding cells to the impacted cell; the penetration resistance and DOP of the grid and cellular STCC targets with similar steel ratio is close, and thus the grid STCC targets with simpler manufacturing process and excellent in-plane expandability are preferred in engineering practice; moreover, the predicted results of DOP model based on the FSCE models agree well with the tested results with the maximum disparity less than 12 % and the proposed model is more applicable to the grid and cellular STCC targets with high radial confinement.     

东莞商业中心超长混凝土结构无缝施工技术

在超长钢筋混凝土结构施工中,为防止混凝土受温度应力和干缩应力而引起开裂,通常采用设置后浇带的方法加以处理.一般每30～40 m设一道后浇带,40～50 d后再浇筑膨胀混凝土.这种常规的后浇带施工,工序复杂,施工时间长,质量不易保证.东莞商业中心三期B区H-6项目工程施工中,结合超长混凝土结构的具体特点,采用超长混凝土结...     

随机性检测方法在加密比特流识别中的应用研究

为识别链路层加密比特流,以未加密与加密数据在随机统计特性上的差异为依据,对4种典型的随机性检测方法在比特流长度不同时的识别率进行了比较研究.针对块内最长游程检测过程中出现的比特流尾部比特位不能构成完整子块的问题,提出了2种可行的处理方案.通过对块内最长游程检测门限值函数的研究,基于参数优化的方法改进了块内最长游程的检测方案,在一定程度上提高了识别率.最后,以某无线网络链路层加密比特流为识别对象,对提出方案的有效性进行了验证.     

FMS 任务可靠性框图模型的建模方法

针对ＦＭＳ具有加工柔性和加工线路柔性的特点,提出了ＦＭＳ任务可靠性框图模型的二种建模方法（并联形式的建模方法、贮备形式的建模方法（冷贮备、热贮备））以及模型的简化方法。本文的目的在于为分析、评估ＦＭＳ可靠性提供理论依据。     

超高分子量聚乙烯纤维混凝土的基本力学性能

针对C70等级高强混凝土,设计了4种超高分子量聚乙烯纤维掺量混凝土,通过立方体抗压、劈裂抗拉和四点弯曲抗折试验,分析了纤维掺量对混凝土力学性能的影响。结果表明:超高分子量聚乙烯纤维对混凝土的抗压强度增强作用不明显,但较大提高了混凝土的抗拉强度和抗折强度,且对混凝土有很好的阻裂、增韧效果。在纤维体积掺量为0.3%~0.5%时,劈裂抗拉强度提高25%以上;掺量0.5%时,弯曲抗折强度提高率超过23%。     

矩阵转置的一种快速算法

本文给出一个数据体积超过计算机可用内存容量的n×n 矩阵快速转置的新方法。与常用的算法相比,所需的计算时间显著减小。     

模拟刚性动能弹丸侵彻混凝土的FE-SPH方法

应用动力有限元与SPH相结合的方法对刚性动性弹丸高速侵彻混凝土靶进行了数值模拟分析,使用HJC本构建模型描述混凝土。计算结果与在57气体炮上所获得的实验数据基本吻合,并能再现侵彻过程中弹的运动及混凝土的飞散、应力波的传播等物理现象。计算结果说明这种新的算法及HJC本构模型用来描述混凝土的侵彻问题是可行和有效的。