预应力FRP筋混凝土梁疲劳性能研究

FRP筋以其耐腐蚀、抗拉强度高、松弛小等特点,在暴露及恶劣条件下的预应力结构中有非常广阔的前景.目前国内外对预应力FRP筋混凝土结构的静力性能已有较多研究,而对于预应力FRP筋混凝土结构的疲劳性能研究,在国外刚刚起步,在国内则是空白.本文在系统地查阅国外最新研究资料的基础上,对FRP筋的疲劳性能、预应力FRP筋混凝土梁的疲劳性能进行了研究与总结,并对今后的发展趋势作了展望.     

日本FRP开发的一些特点

1993年底藉一次出国机会,参观了日本三家生产FRP产品的工厂和一个FRP技术开发公司,并走访了日本FRP协会.感到日本在FRP开发方面具有如下特点,现介绍给大家并进行讨论.     

FRP加固钢筋混凝土结构的防腐阻锈特性研究

纤维增强聚合物(Fiber Reinforced Polymer/Plastic,简称FRP)一般具有不透水和不透气的性质,是一种阻锈性能良好的材料.本文介绍了FRP加固锈蚀混凝土结构抗腐蚀特性的最新研究成果,分析了FRP种类、FRP树脂胶、FRP层数和纤维方向等对防腐效果的影响,并探讨了FRP加固锈蚀混凝土结构的防腐阻锈机理.     

FRP筋与混凝土粘结性能的试验研究及数值模拟

研制加工了一种新型的螺纹状表面粘砂复合材料(FRP)筋,通过对称拉拔试验,对FRP筋与混凝上的粘结机理、破坏机理、粘结强度和滑移性状进行了较为深入的研究.研究结果表明,该螺纹状表面粘砂FRP筋粘结力仍然由摩擦力和机械咬合力提供,但相对而言,摩擦力起主要作用.其破坏机理不是由于FRP筋的外缠肋发生损坏或者与核心处FRP发生剥离.而是FRP筋表面螺纹凸起部分与核心处FRP筋发生剪切滑移,表面粘砂层研磨成粉状,成纵向剪切破坏.荷载-滑移曲线(P-s曲线)在达到峰值点以后下降段比传统螺纹状钢筋平缓,效果更好.与混凝土的粘结强度略低于螺纹钢筋,但明显大于光圆FRP筋.最后,利用ANSYS有限元软件对螺纹状表面粘砂FRP筋混凝土试件进行了数值模拟,模拟结果与试验结果吻合较好,可以得到较为准确的极限状态值,能够用来较为准确的模拟粘结滑移的受力过程.     

纤维增强复合材料(FRP)筋在土木工程中的应用

纤维增强复合材料(FRP)筋材在土木工程中已经有了较多的应用,本文详细分析了FRP筋材在土木工程中的各个方面的应用,指出了FRP筋材与钢材相比存在的优点以及不足,提出了FRP筋材以后的发展方向.     

FRP锚钉锚固长度对FRP加固混凝土构件拉拔性能影响的试验研究

FRP锚钉是能有效阻止FRP加固混凝土构件界面剥离的前沿方法.为了测定FRP锚钉的不同锚固长度对FRP加固混凝土构件粘结性能的影响,采用拉拔试验,参照ACI规范的试验方法,测定了不同锚固长度下FRP加固混凝土构件的拉拔荷载.试验用不安装锚钉的控制试件和安装了15 mm、30 mm、45 mm三组FRP锚钉的试验试件,结果发现,锚固长度不同,FRP加固混凝土构件的破坏模式也各不相同,主要表现为混凝土内部浅层剥离、混凝土锥形破坏、混凝土锥形破坏联合锚钉部分拉拔破坏、混凝土浅层剥离联合锚钉断裂破坏以及FRP加固层内部浅层剥离联合部分混凝土浅层剥离破坏;FRP锚钉的锚固长度越长,加固试件的粘结性能越好;混凝土圆柱体抗压强度设计为30 MPa时,FRP锚钉的锚固长度应不得小于30 mm.试验结论可以为FRP锚钉的设计制作提供参考.     

玻璃钢微型车壳利弊谈

<正> 近年来,随着FRP的工艺技术和原材料品种质量的提高,FRP车壳,特别是微型FRP车壳逐渐被设计部门接受,普遍认为FRP是一种很有前途的车壳用材料,但是,在设计制作FRP微型车壳的过程中,也出现了一些问题,笔者仅就在参于济南摩托车总装厂、山东省荣城汽车改装厂、海南省新大洲摩托车厂研究所设计制造FRP微型车壳的过程中,谈一些粗浅的看法.抛砖     

土木工程自监测纤维复合材料

纤维复合材料(FRP)具有轻质、高强、耐腐蚀、抗疲劳及良好的自传感特性等优点.将FRP与光纤光栅传感技术相结合,即在FRP材料加工过程中埋入光纤光栅传感元件(OFBG)可制成新型自监测复合材料(OFBG-FRP).OFBG-FRP兼有FRP优良的物理力学性能及光纤光栅的智能传感特性.本文主要介绍FRP及OFBG-FRP的传感特性及其在土木工程健康监测中的应用等方面的研究进展.     

日本FRP协会发行图书介绍

《FRP入门》本书为FRP通俗读物,文章深入浅出,可供现场技术员工和FRP经营者使用,内容分为下述章节: 1.FRP;2.生产FRP的材料;3.成形方法;4.FRP的各种特性;5.设计注意事项;6.检查和维修;7.安全卫生和公害对策。     

土木工程用FRP筋的耐久性研究进展

纤维增强塑料(FRP)筋作为一种钢筋替代材料在土木工程中应用日渐广泛。本文对FRP筋在多种环境条件下的耐久性问题的国内外研究进展进行了综述,重点讨论了温度、湿度、酸、碱、盐溶液等环境作用下FRP筋的耐久性及模拟加速环境作用对FRP筋与混凝土界面粘结性能的影响。结果表明,上述环境作用对FRP筋及其与混凝土界面粘结性能的耐久性都有不同程度的影响。另外,本文还给出Fares E.Tannous等人建立的FRP筋在盐、碱溶液侵蚀作用下的耐久性预测模型,并对今后FRP筋的耐久性研究趋势作了展望。     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

几种针状焦性能对比

针状焦分石油系和煤系两大类,这主要取决于针状焦的原料来源。在同一系列中由于原料不同和工艺条件不同 ,针状焦的各自性能也不相同。针状焦是生产超高功率石墨电极和高功率石墨电极的主要原料 ,针状焦的性能对石墨电极的质量有至关重要的影响。所以对针状焦性能以及其对石墨电极质量影响的研究十分必要的。以下是常用的几种进口针状焦和国产针状焦的性能对比。１原料性能分析对比原料试样包括４种针状焦 ,其中两种为进口针状焦：三菱针状焦和新日化针状焦;另两种为国产针状焦：鞍山针状焦和锦州针状焦。其中除锦州针状焦是石油系针状焦外…     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。