钢筋混凝土基础梁设计部分技术问题探讨

本文对钢筋砼框架结构基础梁提出了设置原则和设置位置,并分析了内力计算及构造要求。通过对基础梁的设置分析,认为基础梁双向拉结时,底层结构计算高度可算至基础梁顶面;基础梁局部拉结时,如果仅算至基础梁顶面,则要求基础短柱加大截面做成柱墩,以满足在柱墩上能形成塑性铰的刚度要求。回填土应夯填,地面做成刚性。当不符合以上要求,底层结构计算高度应算至基础顶面。上述分析用于工程设计能满足即安全又经济的要求,可供工程设计参考。     

空心无梁楼盖在某高层综合楼中的应用与思考

某综合楼在建设初期 ,将上部 1 8层肋形楼盖改为等厚空心无梁楼盖 ,2 0 0 2年 5月投入使用。根据新旧两套方案图纸分析了各自的材料耗量 ,针对新方案并未如有关方推荐资料所述可降低混凝土及钢筋用量 ,反而有所增加的情况 ,提出对新设计在计算和构造上的一些意见 ,以期有助于空心无梁楼盖技术的发展推广     

对Lade-Duncan,Matsuoka-Nakai和Ottosen等破坏准则的认识

基于数学推导,Lade-Duncan、修正的Lade-Duncan和Matsuoka-Nakai等屈服破坏准则能被转化为J2=g(θσ)?f(I1)的函数型式,并且相应这三个破坏准则的角隅函数g(θσ)被导出。尽管Lade-Duncan、修正的Lade-Duncan、Matsuoka-Nakai和Ottosen这些破坏准则具有完全不同的数学表达式,但它们都拥有共同的角隅函数和相似的内在本质联系。最后,基于混凝土和粘土的真三轴强度破坏试验结果,分别对上述破坏准则进行了系统地检测,得出了一些有益的结论。     

硬山建筑探源

解析了硬山的概念，研究了硬山这一中国传统屋顶形式的源流，结合制砖技术的发展，对硬山建筑的起源和发展作了简要简述，显示了硬山这种建筑形式的生命力，有利于民居美学的处理。     

浅谈IT系统在医院电气设计中的应用

本文简要阐述IT系统在医院建筑中的应用范围、设计原理及故障分析，并讨论IT系统保护装置的选用原则及实际应用。     

预应力混凝土试件碳化试验及碳化深度预测模型研究

进行了碳化环境下预应力混凝土试件弯曲受拉和直接受压的耐久性试验研究,阐述了碳化作用对预应力混凝土结构的损伤机理。引进拉、压应力状态影响函数χσ,以反映碳化深度和应力状态及应力水平的关系。分别假定Fick第Ⅰ定律中的碳化时间指数α为0.50或为变量,由此建立了多因素影响下的预应力混凝土结构碳化深度预测模型,且采用一次可靠性方法(FORM)对碳化深度预测模型进行了分析。研究结果表明,拉、压应力分别可加快和减缓混凝土结构的碳化速度,χσ反映了碳化速率的变化趋势。最优的碳化时间指数α=0.48,若近似取α=0.50,计算结果也是足够准确的,由此印证了Fick第Ⅰ定律的正确性,而且采用FORM计算预应力混凝土结构碳化深度的离散程度是可靠的。     

平端板连接半刚性梁柱组合节点的抗弯承载力Ⅱ:正弯矩作用

基于现有试验数据以及组合节点抗弯承载力的研究成果,利用塑性分析方法和组件法,提出一种平端板连接组合节点承受正弯矩作用时,其塑性抗弯承载力的计算方法。探讨组合节点的实效模式,给出其各组件承载力的计算方法,组件包括螺栓、柱腹板、梁翼缘、混凝土楼板等。考虑中和轴出现的5种位置:混凝土楼板内;钢梁上翼缘内;钢梁腹板内,所有螺栓受拉;前m-1排螺栓受拉,第m排部分受拉,其余受压;1～m排完全受拉。该方法可以考虑节点承受非对称荷载作用的情况以及作用在连接上的剪力、高强度螺栓撬力等因素的影响。如果不考虑组合楼板的影响,使用该方法同样可以计算平端板连接梁柱纯钢节点在承受正弯矩作用时的抗弯承载力。     

Deep‐UV exciton emission from Mg1 − xCaxO—A first‐principle investigation

In order to investigate the ultraviolet and electron emission properties of rock‐salt Mg_{1 ? x}Ca_xO, first‐principle calculations are carried out with x ranging from 0 to 0.5. The electron–hole interaction is taken into account by solving the Bethe–Salpeter equation. In pure MgO, the calculated exciton binding‐energy value of 83 ± 3 meV is quite close to the published experimental values. The electronic properties of doped MgO are investigated based on the super‐cell model. Both the optical bandgap and the exciton binding energy of the super cell of Mg_{1 ? x}Ca_xO are calculated for five discrete compositions, with an increasing amount x of CaO. The results show that there are strong excitonic effects in all of these materials. A rapid reduction in bandgap value is observed for Mg_{1 ? x}Ca_xO, when increasing the x value. The exciton binding energy of Mg_{1 ? x}Ca_xO shows a minimum value of about 40 meV around x = 0.2. In all of these cases, the exciton is stable at room temperature. The lowest excitation levels in Mg_{1 ? x}Ca_xO are determined by dark excitons. The occurrence of these dark excitons might explain why Mg_{1 ? x}Ca_xO is a strong source of delayed electron emission, after being bombarded by ions in a plasma.     

Visual Evaluation of Binding to Mucosal Cells of a Medical Device Against the Common Cold

The objective of this study was to investigate the possibility of visualizing the ability of hydroxypropylmethylcellulose (HPMC) and a nasal spray (First Defense), in which the bioadhesive is HPMC, to bind to human mucosal cells using inorganic (black carbon particles and Congo red dye) and organic markers (Escherichia coli). A significant reduction in the bacterial adhesiveness has been observed. Our findings indicate the possibility of counteracting the lock-and-key mechanism of microorganism adhesion using the bioadhesive properties of polymers, such as HPMC, in First Defense to prevent a possible contact between adhesins and complementary receptors.     

Seasonality: Nature,People's Preferences and Urban Planning in Oulunsalo,Finland

Seasonal changes are particularly strong in northern Europe. Daylight, temperature, flora, fauna and landscape change from day to day. We discuss how seasonality exists in nature, is felt by people and is reflected in urban planning. The case study regards Oulunsalo municipality with a population of 9,000 at the northern most Baltic Sea coast in Finland. In 2003 the mean temperature of the coldest month in Oulunsalo was ?16.4 and the warmest +19.5 centigrade. The longest day was 22 hours 3 minutes and the shortest 3 hours and 35 minutes. A survey among the adult Oulunsalo population shows that summer is the best season for the majority of people (72%)—more often for men (78%) than for women (66%). Almost everybody (96%) likes the change of seasons. Seasons and seasonal preferences should be considered more in urban planning processes and land-use plans.