超高韧性水泥基复合材料弯曲性能及韧性评价方法  

Research on flexural properties and flexural toughness evaluation method of ultra high toughness cementitious composites

作　　者：李贺东[1] 徐世烺[2] 

机构地区：[1]大连理工大学,辽宁大连116024 [2]浙江大学,杭州310058

出　　处：《土木工程学报》2010年第3期32-39,共8页China Civil Engineering Journal

基　　金：国家自然科学基金重点项目(50438010);南水北调工程建设重大关键技术研究及应用(JGZXJJ2006-13)

摘　　要：本文利用薄板试件和梁试件,采用三分点加载,对超高韧性水泥基复合材料(Ultra High Toughness Cementitious Composite,简称UHTCC)的受弯性能进行了试验研究,并在试验结果的基础上探讨了适于UHTCC弯曲韧性的评价方法。薄板四点弯曲试验表明,UHTCC材料具有可与金属相比拟的弯曲变形能力。四点弯曲梁试验表明,UHTCC材料具有优异的裂缝无害化分散能力,在荷载达到峰值裂缝开始局部化扩展之前,裂缝在整个梁深几乎始终以扁平形式存在和扩展,宽度始终保持在几十个微米量级,不同梁深位置的变形协调通过裂缝条数的变化实现。梁试验表明,UHTCC具有非常高的耗能能力,到达峰值荷载时消耗的能量是对应钢纤维消耗能量的13倍,该材料试件在跨中挠度达到l/60时仍能够保持良好的完整性,是用于结构抗震的理想材料。在弯曲韧性的评价方法分析中发现,ASTMC1018方法中的韧性指数用于评价UHTCC可能会引起一定的误导,将限定计算挠度扩展后的JSCE-SF4方法能够很好地描述该材料的耗能能力,而本文定义的"变形硬化系数法"通过给出不同变形情况下的抗弯强度,不仅能够有效评价UHTCC的韧性特征,也能够很好地满足当前结构设计的需求,总之,经过改进后的JSCE-SF4方法结合"变形硬化系数法"能够从能量和强度两个方面全面地评价UHTCC的弯曲韧性。An experimental study on the flexural properties of Ultra High Toughness Cementitious Composites （UHTCC） was carried out, and discussions on how to effectively evaluate the flexural toughness of UHTCC were presented. Threepoint bending tests on thin plates indicate that the UHTCC possesses ultra high deformability comparable with metal. Three-point bending tests on beams indicate that the UHTCC can effectively disperse harmful cracks into harmless ones and maintain excellent integrity even under large mid-span deflection of about 1/60. The tests also reveal that the UHTCC possessed ultra high energy dissipation capacity, 13 times that of SFRC until the loads reach the respective peak values. It is found that ASTM C 1018 method is not appropriate for UHTCC, while the modified JSCE-SF4 combined with the proposed Deflection Hardening Indices method may provide overall evaluation of the flexural touzhness of UHTCC.

关 键 词：超高韧性水泥基复合材料 聚乙烯醇纤维 四点弯曲试验 弯曲韧性 裂缝 变形硬化 

分 类 号：TU502.6[建筑科学—建筑技术科学] TU528.58