邓宗才, 董智福
AuthorsHTML:邓宗才, 董智福
AuthorsListE:Deng Zongcai, Dong Zhifu
AuthorsHTMLE:Deng Zongcai, Dong Zhifu
Unit:北京工业大学城市与工程安全减灾教育部重点实验室，北京 100124
Unit_EngLish:Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing 100124, China
Abstract_Chinese:为了深入了解纤维混凝土的耐冲击性能, 进行了不同体积掺率的高锆耐碱集束型玻璃纤维、粗聚丙烯纤维增强混凝土板的耐冲击性能的试验研究．通过试件的破坏形态、落锤的加速度时程和板底支座反力时程曲线, 结合高速摄像机记录的整个试件冲击破坏过程, 从动力学角度研究了纤维种类及纤维体积掺率对混凝土板耐冲击性能的改善效果．结果表明：经第2次冲击后, 素混凝土与纤维混凝土板的破坏模式不同, 素混凝土板呈脆性破坏, 沿对角线方向破碎成4块; 体积掺率为0.75% 的粗聚丙烯纤维混凝土板的损伤最小, 板底出现9条主裂缝, 无大面积混凝土崩落, 板的塑形变形较大; 体积掺率为0.75% 的高锆耐碱集束型玻璃纤维混凝土板的板底出现9条主裂缝, 最大裂缝宽度仅为0.8 cm, 底部出现半径约为8 cm的圆形混凝土崩落区域．通过加速度时程曲线可知, 素混凝土与纤维混凝土板破坏过程也存在明显差异．在弹性变形阶段, 纤维混凝土冲击持续时间比素混凝土约长1 ms; 裂缝扩展及混凝土崩落阶段, 当加速度降到约为峰值的1/3时, 素混凝土板呈现脆性破坏, 而纤维混凝土板的加速度时程曲线出现二次强化现象, 呈延性破坏, 纤维显著改善了板的冲击韧性, 且纤维体积掺率越高, 耐冲击性能改善效果越明显．
Abstract_English:The purpose of paper is to gain a better understanding of the impact resistance of fiber reinforced concrete，and experiments were conducted on the impact resistance properties of alkali-resistant glass fiber of high zirconium and coarse polypropylene fiber reinforced concrete slabs with different volume fraction contents. From the dynamic point of view，the improvement effects of fiber type and fiber volume fraction on the impact resistance of concrete slab were studied through the failure morphology of the specimen，the acceleration time history of the drop hammer and the reaction time history curve of the bearing at the bottom，combined with the impact damage process of the whole specimen recorded by the high-speed camera. It is found that after the second impact，the damage degree of plain concrete and fiber reinforced concrete slab is different. The plain concrete slab is brittle and broken into four blocks in the diagonal direction. The slab of coarse polypropylene fiber reinforced concrete with the volume fraction of 0.75% has the slightest damage with nine main cracks at the bottom of the slab，without large area concrete caving，and the deformation of the slab is large. The slab of alkali-resistant glass fiber of high zirconium reinforced concrete with the volume fraction of 0.75% has nine main cracks at the bottom of the slab，the maximum crack width is only 0.8 cm，and the emergence of a round concrete caving area with a radius of about 8 cm at the bottom of slab is observed. Through the time history of acceleration，it can be seen that there are significant differences in the failure process of the slab between plain concrete and fiber reinforced concrete slab. In the elastic deformation stage，the duration of the impact of fiber concrete is about 1 ms longer than that of plain concrete. In the stages of crack propagation and concrete collapse，when the acceleration decreases to about 1/3 of the peak，the plain concrete slab shows the tendency of brittle failure. The acceleration time history curve of the fiber concrete slab shows the secondary strengthening，which is ductile failure. Fiber significantly improves the impact toughness of the sheet，and the higher the fiber volume fraction，the more pronounced the improvement in impact resistance.
Keyword_Chinese:纤维混凝土; 落锤试验; 高锆耐碱玻璃纤维; 聚丙烯纤维
Keywords_English:fiber reinforced concrete; drop hammer test; alkali-resistant glass fiber of high zirconium; polypropylene fiber

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