钢纤维混凝土弯曲韧性及残余抗折强度试验研究

发布时间：2018-02-05 01:04

本文关键词： 钢纤维混凝土弯曲韧性残余抗折强度裂缝嘴张开位移荷载-挠度曲线　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：钢纤维混凝土作为一种新型复合建筑材料,已广泛应用于建筑结构与工程实际中。除强度指标外,韧性也是钢纤维混凝土的一种重要性能,而弯曲韧性是衡量钢纤维混凝土韧性的重要指标。国内外一些学者以及各国标准规范相继提出了不同的试验方法与评价指标来表示钢纤维混凝土的弯曲韧性,但国内对于钢纤维混凝土弯曲韧性评价方法中残余抗折强度的研究还较少,随着钢纤维生产工艺与技术的进步,对于新型钢纤维增强增韧混凝土弯曲性能的研究还有待深入。本文依据我国《钢纤维混凝土》(JG/T 472-2015)、《纤维混凝土试验方法标准》(CECS13:2009)和欧洲标准(EN14651)进行了棱柱体三分点加载试验和切口梁单点加载试验,分析和研究了钢纤维混凝土的弯曲韧性及残余抗折强度。主要研究内容及结论如下:1、进行了54组共162个150mm×150mm×150mm钢纤维混凝土立方体试件的抗压试验、24组共72根150mm×150mm×550mm钢纤维混凝土棱柱体小梁的三分点弯曲韧性试验和54组共216根150mm×150mm×550mm钢纤维混凝土切口梁单点加载弯曲韧性试验,研究了钢纤维体积率、混凝土强度、钢纤维类型对弯曲韧性及残余抗折强度的影响规律。研究结果表明:在不同的试验方法下,试件的弯曲韧性指标随着钢纤维体积率与混凝土强度的提高均有增长趋势,其中,后期的等效抗折强度与残余抗折强度的增长尤为显著;钢纤维类型对于比例极限强度的提高影响并不明显,钢纤维类型对于混凝土弯曲韧性的影响主要体现在混凝土破坏后期等效抗折强度或残余抗折强度的提高上,其中4D、5D型钢纤维增强增韧效果更好。2、对比分析了三分点法(JG/T 472-2015)、切口梁法(CECS13:2009)和切口梁法(EN14651)三种弯曲韧性评价指标的适用性。结果表明:切口梁法比例极限强度的计算条件(挠度δ或裂缝嘴张开位移CMOD≤0.05mm)限制了钢纤维混凝土抗折强度的取值范围,相比之下,三分点法更适合表征高强高掺量钢纤维混凝土的弯曲韧性;切口梁法因其能够测得素混凝土和小掺量钢纤维混凝土的荷载-挠度/裂缝嘴张开位移曲线下降段,更适合表征低掺量钢纤维混凝土和素混凝土的弯曲韧性。3、基于三分点法荷载-挠度曲线和切口梁法荷载-挠度/裂缝嘴张开位移曲线的走势与线下面积积分所得能量吸收值,分析了三种方法的特点与不足、联系与区别,得出结论:因切口梁法的荷载-挠度曲线与荷载-裂缝嘴张开位移曲线走势基本一致,荷载-挠度曲线对应的抗折强度fm、等效抗折强度feq1、feq2与荷载-裂缝嘴张开位移曲线对应的比例极限强度ct L ff,、残余抗折强度R,1f、R,2f在数值上也较为接近;切口梁法开裂能量吸收值crD存在不适用于CECS13:2009计算方法的情况,因此CECS13:2009切口梁法能否对不适用情况下试件的弯曲韧性进行准确评价还有待进一步研究,而使用EN14651切口梁法对弯曲韧性进行评价则不依据于能量法,残余抗折强度能更好地反映出钢纤维混凝土弯曲韧性的变化趋势。
[Abstract]:As a kind of new composite materials of steel fiber reinforced concrete, has been widely used in building structure and engineering practice. Besides the strength index, one of the most important performance and toughness of steel fiber reinforced concrete, the flexural toughness is an important index to measure the toughness of steel fiber reinforced concrete. Some scholars at home and abroad as well as the standard test methods have been proposed different from the evaluation index to represent the flexural toughness of steel fiber reinforced concrete, but the domestic research on the flexural strength of residual flexural toughness of steel fiber reinforced concrete is less evaluation methods, with the technology and technology of steel fiber production progress, for the new type of steel fiber reinforced concrete bending properties of toughening still need to be further researched. On the basis of steel fiber our country < > concrete (JG/T 472-2015), standard test method for concrete > < fiber (CECS13:2009) and the European standard (EN14651) of edge column three Point loading test and notched beam single point loading test, flexural toughness and residual analysis and Research on the bending strength of steel fiber reinforced concrete. The main research contents and conclusions are as follows: 1, the 54 groups of 162 150mm * 150mm * 150mm steel fiber concrete cube compressive test, three point bending toughness test 24 group of 72 150mm * 150mm * 550mm steel fiber concrete prism beam and a total of 54 groups of 216 150mm * 150mm * 550mm steel fiber reinforced concrete single point loading notched beam flexural toughness test, the steel fiber volume ratio, concrete strength, effect of steel fiber type on the flexural toughness and flexural strength the research results show that: in the different test methods, test pieces with the flexural toughness index growth trend, the volume fraction of steel fiber and concrete strength with the increase in the late equivalent flexural strength and flexural strength The growth is particularly significant; the type of steel fiber to improve the strength of the proportional limit effect is not obvious, the type of steel fiber to influence the flexural toughness of concrete is mainly reflected in the late failure of concrete flexural strength or equivalent flexural strength increased, including 4D, 5D type steel fiber reinforced and toughening effect of.2 is better, a comparative analysis of three points method (JG/T 472-2015), notched beam method (CECS13:2009) and notched beam method (EN14651) for the three indexes to evaluate the flexural toughness. The results show that the calculation conditions of ultimate strength of notched beam method (the ratio of deflection or crack mouth opening displacement CMOD = 0.05mm) compared with the range limit, the flexural strength of steel fiber concrete under three point bending toughness method is more suitable for the characterization of high strength steel fiber reinforced concrete; notched beam method because it can measure the element load of concrete and small dosage of steel fiber reinforced concrete torsion Degree / crack mouth opening displacement curve decreased,.3 flexural toughness is more suitable for the characterization of low content of steel fiber reinforced concrete and plain concrete, and the three point line area trend method of load deflection curves and notched beam method load deflection / crack mouth opening displacement curve under the integral energy absorption value based on the analysis of characteristics of three methods and shortcomings, and difference, draw the conclusion: because of the load deflection curves of notched beam method and load crack mouth opening displacement curve is basically the same trend, the load deflection curve corresponding to the flexural strength of FM, the equivalent flexural strength of feq1, feq2 and load crack mouth opening displacement curve corresponds to the proportional limit CT L FF, residual strength, flexural strength of R, 1f, R, 2f is relatively close in value; notched beam method crack energy absorption value crD is not applicable to the CECS13:2009 calculation method, so the CECS13:2009 notch beam method can not The accurate evaluation of flexural toughness of specimens is still needed to be further studied. The evaluation of flexural toughness by EN14651 notched beam method is not based on energy method. Residual flexural strength can better reflect the trend of flexural toughness of TBF.

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.572

【相似文献】