UHTCC薄板弯曲荷载-变形硬化曲线与单轴拉伸应力-应变硬化曲线对应关系研究

STUDY ON CORRESPONDING RELATIONSHIPS BETWEEN FLEXURAL LOAD-DEFORMATION HARDENING CURVES AND TENSILE STRESS-STRAIN HARDENING CURVES OF UHTCC

单轴拉伸试验是评价超高韧性水泥基复合材料(以下简称UHTCC)力学性能的有效试验方法,但是由于其实际操作困难,不便于广泛使用。该文通过四点弯曲试验和单轴拉伸试验研究了UHTCC的弯曲性能和拉伸性能,对比分析了UHTCC的薄板弯曲荷载-变形硬化曲线和单轴拉伸应力-应变硬化曲线以及UHTCC的基本力学指标、韧性指标、延性指标和多缝开裂形式。试验结果表明四点弯曲试验可以反映UHTCC的应变硬化、多缝开裂、高延性和高韧性性能。基于理论分析和试验结果推导了极限拉伸应变的计算公式,并通过试验结果进行了验证,结果表明通过计算公式得到的预测值与试验结果吻合较好。因此四点弯曲试验可以代替单轴拉伸试验成为评价UHTCC特殊力学性能的简单实用的试验方法。

Uniaxial tensile test is an effective method for investigating the mechanical performance of UHTCC （short for Ultra High Toughness Cementitious Composite）. However, its application is limited due to difficulties in performing such a test. In this paper, the flexural properties and uniaxial tensile properties are studied by four-point bending test and uniaxial tensile test respectively. Comparisons are made between flexural load-deformation hardening curves and tensile stress-strain hardening curves, as well as basic mechanical indexes, toughness indexes, ductility indexes and multiple cracking patterns. The test results show that the strain hardening performance, multiple cracking, ultimate high ductility and toughness can be reflected by four-point bending test. An ultimate tensile strain formula is proposed based on theory analysis and test results. The predicted values calculated by the formula agree well with the test results; hence the validity of the formula is verified. The four-point bending test method is a simple and practical method, which can substitute for the uniaxial tensile test method to estimate the special mechanical performance of UHTCC.