超长隔震结构抗震性能与抗倒塌能力研究

采用增量动力分析(Incremental Dynamic Analysis,IDA)方法,得到了整体式与多塔式超长隔震结构进入各破坏状态的地震峰值加速度,分析了结构的抗震性能与抗倒塌能力。IDA分析结果表明:与多塔结构相比,整体式结构更易发生破坏,所以多塔结构的抗倒塌能力略强于整体结构,但两个结构在设计大震下的倒塌概率都小于5%,可以认为能达到大震不倒的安全要求。     

基于玻化微珠保温混凝土的中小学校舍抗震加固与节能改造一体化研究

结合太原市某小学教学楼抗震加固工程,设计了该教学楼抗震加固与节能改造一体化方案,应用dest-c模型对其进行了抗震分析和节能分析.研究表明,玻化微珠保温混凝土在抗震加固与节能改造一体化中具有优越性.     

基于钢筋锈损截面面积的锈胀裂缝宽度计算模型

通过锈胀裂缝宽度预测混凝土结构中钢筋锈蚀程度是一种实用的非破损检测方法。然而,针对此问题的研究采用的方法不一、参数各异,所得的结论和所建立的计算模型之间也存在较大分歧。针对大量相关研究成果进行综合分析发现,锈胀裂缝的发展与局部区域内锈蚀产物的绝对生成量之间存在直接关系,锈胀裂缝宽度随着平均锈损截面面积的增大近似成线性增大,混凝土保护层厚度和钢筋直径对其无明显影响。通过锈蚀钢筋的三维扫描建立虚拟模型,建立区段最大截面锈蚀率与平均锈蚀率的转换关系。在此基础上综合已有自然锈蚀数据,建立了基于钢筋平均锈损截面面积的锈胀裂缝宽度计算公式,可对实际工程锈胀混凝土构件中的钢筋锈蚀程度给出合理估测。     

高大恒温装配车间两种送回风方式空调系统模拟对比与实测研究

对上送下回与侧送下回气流组织进行了模拟分析及实测验证,研究了车间温度、速度分布规律.结果表明,在相同的送风条件下,采用侧送下回气流组织,车间内温度可降低1℃左右,温度场和速度场分布更均匀,气流组织更合理.     

烟道孔对钢烟囱的影响分析

烟道孔是烟囱的重要组成部分,在设计中多数按经验公式计算或按构造处理,不能正确反映对整体烟囱的影响.以高50 m,直径为4.4m的实际钢烟囱为例,用数值分析方法研究烟道孔对其静、动力特性,温度应力及地震响应的影响.研究表明,烟道孔周围不仅受力复杂,而且对整个烟囱的受力和变形有较大的影响;开孔引起应力集中,使风载和自重作用下的最大应力增加了近2倍,温度应力增加80％;开孔使烟囱的基频减小10％,地震应力响应增加了2倍多.     

Analytical behavior of eccentrically loaded concrete encased steel columns subjected to standard fire including cooling phase

A nonlinear 3-D finite element analysis (FEA) model was developed to predict the behavior of eccentrically loaded concrete encased steel (CES) columns subjected to ISO-834 standard fire including heating and cooling phases. The finite element model has been validated against published tests conducted at elevated temperatures. Comparisons between the predicted results and the test results show that this model can accurately predict the behavior of CES columns under fire. The FEA model was then used to investigate the typical temperature-time curve and mid-height lateral deformation-time curve of eccentric compression CES columns in a complete loading history including initial loading, heating and cooling. It is shown that the temperature delay is obvious at the inner layers of concrete. The fire resistance of a CES column should be checked for the full process of fire exposure until temperatures everywhere in the column start to decrease. The lateral deformation of the column still gradually increases during the cooling phase and the column may fail during that phase. There is a large residual deformation after the fire exposure. Furthermore, the variables that influence the behavior of the CES columns under fire were investigated in parametric studies. It is found that the main parameters which influence the lateral deformation-time curve of the column during the full process of fire exposure are load ratio, slenderness ratio, duration time, depth to width ratio and steel ratio, and the main parameters which influence the residual deformation ratio of the column after fire are load ratio, duration time, cross-sectional depth and steel ratio.     

渐变超高大悬挑结构施工的时变性研究

针对某口岸综合楼主体结构"逐层渐变、多层悬挑、超高"等特点,建立结构与支撑体系的统一模型,并利用有限元的"基于时间属性"技术,模拟了结构与支撑体系共同作用的时变过程,同时通过对比施工监测数据,揭示了支撑体系内力变化规律,解决了常规脚手架计算方法无法适用于本工程的技术难题,为现场的安全可靠施工提供了理论依据。     

Urea–formaldehyde resin prepared with concentrated formaldehyde

The characteristics of UF resin prepared with concentrated formaldehyde were studied in this paper. With the molar ratio F/U = 1.1, the UF resin prepared with concentrated formaldehyde showed better mechanical properties than that with formalin. The ¹³C-NMR and FTIR results indicated that there were more methylene groups, ether groups and urons in a UF resin system prepared with concentrated formaldehyde than those in a normal UF resin. The differential scanning calorimetry and DMA results showed that the curing temperature of UF resin with concentrated formaldehyde was lower than that of a normal UF resin. UF resin with concentrated formaldehyde showed worse thermal stability and higher thermal decomposition temperature.     

水质变化时垢层对铸铁腐蚀的影响作用

通过对水质变化时铸铁腐蚀速率与铁释放的对比,研究垢层对铸铁腐蚀的影响作用。结果表明,改变水的硬度和拉森指数(LR),对铸铁的腐蚀速率与铁释放均有明显影响;低硬度水质条件下形成的管垢以较易分解和转化的Fe(OH)_3为主,而较为稳定的Fe_3O_4含量较低,在硬度或LR改变时,管垢破坏严重,铸铁基底腐蚀加剧;高硬度水质下形成的管垢较为致密,表面覆盖大量的CaCO_3,且含有较多Fe_3O_4和FeOOH,管垢整体结构稳定,在硬度或LR改变时,能抑制铸铁基底的进一步腐蚀。