钢纤维砼韧性及压缩韧性指标的研究

An Investigation of the Toughness and Compressive Toughness Index of Steel Fiber Reinforced Concrete

本文首先分析比较了国内外提出的关于钢纤维砼(SFRC)各种有代表性的韧性指标。基于评价SFRC韧性指标的五个原则,提出用韧度指数(?)和承载能力变化系数(?)作SFRC的压缩韧性指标。从分析砼试件单向受压时裂缝开裂和传播过程及钢纤维的作用,认定与非稳定裂缝传播阶段开始时的荷载——临界荷载P_(cr)对应的临界点,是SFRC试件压缩过程的重要特征点,并取P_(cr)=O.85(?)。最后,作者通过五组不同纤维率试件的压缩试验,证明所提出的指标体系是可取的,能够充分反映不同纤维率的增韧效果。

In this paper, various methods for determining the toughness of steel fiber reinforced concrete ( SFRC ) have been compared and evaluated using the five criteria. It is found that the ASTM C1018-85method conforms mostly to these criteria, and hence has been accepted as the foundation for China's standard test method of com-pressive toughness of SFRC. In which,the critical-load point is proposed to replace the first-crack point in defining the compressive toughness index based on an analysis of the onset and propagation of cracks in concrete under uniaxial loading. The transient coefficient for load-carrying capacity K(n)a is also given to indicate the va-riational characteristic of toughness. Experiments consisting of five groups of specimens with different percentages of fiber content have been carried out to verify the validity of the recommended index.