配筋混凝土砌块剪力墙结构的发展前景

配筋混凝土砌块剪力墙结构是一种新型结构体系.其最大优点是抗震性好、造价较低,适用于我国广大乡村及城镇地区的住宅建筑.介绍配筋混凝土砌块剪力墙结构的发展概况及其优越性,同时,对该结构的应用前景进行了分析,并提出该结构在研究和应用中应解决的问题.     

Damage model of fresh concrete in sulphate environment

A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into three regions: an expanded and dense region; a crack-development region; and a noncorroded region. Second, based on the thickness of the surface corrosion layer and the rate of loss of compressive strength of the corroding region, a computational model of the concrete blocks’ corrosion-resistance coefficient of compressive strength in a sulphate environment was generated. Third, experimental tests of the corrosion of concrete were conducted by immersing specimens in a corrosive medium for 270 d. A comparison of the experimental results with the computational formulae shows that the calculation results and test results are in good agreement. A parameter analysis reveals that the corrosion reaction plays a major role in the corrosion of fresh concrete containing ordinary Portland cement,but the diffusion of the corrosion medium plays a major role in the corrosion of concrete mixtures containing fly ash and sulphate-resistant cement. Fresh concrete with a high water-to-cement ratio shows high performance during the whole experiment process whereas fresh concrete with a low water-to-cement ratio shows poor performance during the late experiment period.     

保护层厚度对基础梁配筋的影响研究

针对整体建模情况下基础梁与框架梁保护层厚度不一致的问题,文章首先从理论上分析了保护层厚度对梁配筋的影响,并用SATWE程序对某框架结构基础梁配筋在不同混凝土强度等级和保护层厚度条件下进行了定量计算与分析,为计算基础梁配筋合理选择保护层厚度提供了参考。     

硫酸盐环境下混凝土抗压强度耐蚀系数研究

基于混凝土腐蚀层厚度及腐蚀区混凝土抗压强度损失率的概念,建立了硫酸盐环境下混凝土试块的蚀强模型.根据该模型推导出混凝土抗压强度耐蚀系数计算公式,同时进行了3组全浸泡混凝土的腐蚀试验,并根据试验结果对混凝土抗压强度耐蚀系数计算公式进行拟合和参数分析.结果表明：根据所建立的模型得到的混凝土抗压强度耐蚀系数计算结果与试验结果吻合较好;硫酸盐环境下混凝土可划分为裂缝发展区、膨胀密实区和未腐蚀区3个区域;综合性的腐蚀系数可以反映混凝土配合比与抗硫酸盐腐蚀性的关系,腐蚀系数越大,抗硫酸盐腐蚀性越差.根据所建立的模型和计算方法能够评估和预测硫酸盐环境下混凝土的抗腐蚀性能.     

汶川地震后建筑的抗震加固技术

汶川地震建筑震害再一次证明了进行抗震加固是提高现有房屋抗震能力最有效的途径.本文从震害资料出发,论述了抗震加固的必要性和重要性.同时将抗震加固方法分为传统加固方法和新型加固方法两大类,并建议优先选用效果可靠的传统加固方法.最后,分析了框架节点区加固、结构胶防火、变形缝处构件的加固等难点问题,并提出了处理方法.