用声发射技术研究水泥基复合材料脆性

观测了不同种类混凝土三点弯曲梁的声发射（AE）特性,发现掺加纤维对声发射特性有明显影响。掺加纤维的混凝土梁,声发射事件突发性明显减小,采用Weibull函数方法定量分析了材料特性对混凝土试件的声发射特性、断裂特性及脆性的影响。结果表明,参数m和θ具有明显的物理意义,m值表征由材料特性引起的脆性,而θ值表征由试件几何尺寸引起的试件脆性。     

在面板周围应用接触单元研究非岩基趾板对面板应力变形的影响

本文以山东泰安抽水蓄能电站上池的混凝土面板堆石坝作为研究实体,在面板与趾板之间,面板与面板之间,面板与垫层之间,河床部位的趾板与垫层之间,趾板与趾板之间采用接触单元,对堆石坝进行三维非线性有限元计算,研究分析河床坝段趾板建在堆石体上对面板应力,变形以及周边缝位移的影响,计算结果表明,这些应力和位移是趾板建在岩基上的一般面板堆石坝有不同的变化规律,但尚未超出一些已建工程相应的实测值。     

The effect of surface preparation on the bond interface between FRP sheets and concrete members

Fiber-reinforced polymer (FRP) composite wraps have been established as an effective method for rehabilitation and strengthening of concrete structures. They are being increasingly used as an alternative to steel for reinforcing and strengthening of concrete structures. This paper presents the experimental and analytical results of the influence of concrete surface treatment and the type of FRP sheets on the bonding strength of concrete-FRP sheet. The FRP sheets were bonded to concrete beams in two opposite sides using an epoxy resin. Variables included the type of fiber (C1, C5, and GE) and the surface treatment (water jet and sanding). With changing the surface treatment of concrete surface preparation and the type of fiber sheets, the bonding strength, bonding load–strain response and failure modes were investigated. The concrete specimens with surface roughened with water jet showed much better bonding strength than those roughened with an ordinary sander. Equations for predicting the bond load failure of concrete specimens externally bonded with carbon and glass fiber sheets compared well with those of experimental.     

混凝土塑性损伤模型参数的选取与验证计算

基于塑性损伤的混凝土本构模型,现行规范与ABAQUS软件给出的应力-应变关系表达式有所不同。在对两种表达式进行分析对比的基础上,对ABAQUS软件自带的混凝土塑性损伤模型(CDP模型)参数选取进行了分析,并给出了该模型参数的选取和调整方法。为了验证模型参数选取的合理性和可靠性,采用ABAQUS软件对算例试验构件进行了有限元数值分析,并将数值分析所得的荷载-位移曲线与试验测试曲线进行对比。结果表明:所选的参数能够满足数值分析的精度要求。     

水府庙水库大桥主桥设计

本文介绍了水府庙水库大桥预应力混凝土连续刚构的构造,结构计算特点,深水基础施工方案选择。     

三合一混凝土料斗在灌注桩施工中的应用

根据灌注桩施工特点,研制了新型料斗,一器多用,加快了砼运输速度,缩短了灌注时间,减少了浪费,提高了成桩速度。     

机车柴油机机油的发展

机油对机车柴油机的动力性能、经济性、可靠性和耐久性有着直接影响,正确地选择和使用机油对柴油机的四性有着决定性的作用。本文介绍了机车柴油机机油的作用、发展、主要技术指标和报废限度及其在使用中的注意事项。     

化学短纤维混凝土的电镜测试研究

应用扫描电镜对加入化学短纤维的硬化混凝土进行测定,结果表明,改性后的混凝土在强度方面并无显著变化,但其裂缝的开展宽度大为减小,试算的结构延性增加甚多,因而该混凝土用于抗震结构有良好的前景。     

Bond of ribbed galvanized reinforcing steel in concrete

The ASTM beam end test (ASTM A944) has been used to compare the bond and slip behaviour of deformed (i.e. ribbed) galvanized, epoxy-coated and black steel bars in concrete. The objective was to determine whether galvanizing adversely affects bond strength. From a series of thirty specimens, the average bond strength of black steel and galvanized steel reinforcement used in these tests has been determined and bond stress has been shown to act uniformly over the embedded bar area. A slip value of approximately 0.4 mm has been confirmed to be associated with bond failure by concrete splitting. The results indicated that while epoxy coating resulted in a significant loss in bond strength of the order of 20% compared to black steel, there is no adverse effect on bond with the use of galvanized steel. Chromate treatment of galvanized bars is deemed unnecessary since there was no evidence of long term reduction in bond due to the possible effects of hydrogen gas evolution resulting from the reaction between zinc and wet concrete.     

包管混凝土的拆除爆破

介绍了包管混凝土的拆除爆破方法 ,爆破参数以及为了保护被包围在混凝土内的水管所采取的各种技术措施