钢纤维对超高性能混凝土裂后性能的影响

Research on the Post-cracking Performance of UHPC with Steel Fiber

通过对超高性能混凝土(Ultra-High Performance Concrete,简称UHPC)进行三点弯曲的试验。研究了不同类型、不同掺量以及不同长径比的钢纤维对UHPC材料裂后性能的影响,根据实测荷载-裂缝张开位移(CMOD)曲线,通过反分析确定了UHPC的应力-裂缝宽度关系。研究结果表明:端钩型纤维对UHPC材料裂后的应力提高幅度要高于直线型纤维;纤维掺量的增加可以有效提高UHPC材料裂后的应力,但钢纤维的应力提高幅度也逐渐下降;长径比的增长可以提高钢纤维的应力提高幅度,但在较高纤维掺量情况下,长径比较长的钢纤维因为在基体中分散不均匀,导致UHPC材料裂后应力反而有所下降。

Based on the study of the UHPC(Ultra-High Performance Concrete)for three-point bending test,the effect of different shape,different content and different length to diameter ration of steel fiber on the post-cracking performance of the UHPC specimens have been investigated.The tensile stress-crack opening relationship of UHPC is determined by back analysis using load versus crack mouth opening displacement(CMOD)curve from notched beams.The results show that the enhancement of hooked-end fibers is greater than that of the straight fibers.With the improvement of fiber content,the tensile stress of the UHPC has improved significantly after the crack,but the reinforcing efficiency of steel fiber is also gradually decline.The increase of length to diameter ratio of steel fiber can significantly improve the tensile stress of the UHPC,but the steel fiber with longer length to diameter can result in lower tensile stress of UHPC when under the condition of high fiber content.