Impact resistance of porosity-free fiber-reinforced concrete (PFFRC) beams under low-velocity impact loading
Impact resistance of porosity-free fiber-reinforced concrete (PFFRC) beams under low-velocity impact loading
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DOI：
10.1177/20414196211069573
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发表时间：
2022-02
影响因子：
2
通讯作者：
N. Kishi;M. Komuro;K. Kono;Tomoki Kawarai
中科院分区：
文献类型：
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作者：
N. Kishi;M. Komuro;K. Kono;Tomoki Kawarai
超高性能纤维混凝土是一种先进的水泥基复合材料。它的抗压强度和高延性可以使结构构件小型化，特别适用于高层建筑。这些优异的机械性能也使其在防护结构中的应用能够抵抗高速穿透，低速冲击和爆炸载荷。UHPFRC具有约150-200 MPa的抗压强度，传统上用于研究低速冲击载荷下结构构件的抗冲击性。然而，最近，已经开发了400 MPa级抗压强度的无孔隙混凝土。为了研究混凝土强度和钢纤维体积含量对无孔隙纤维混凝土（PFFRC）构件抗冲击性能的影响，对钢纤维体积含量为1 ~ 3.5%的PFFRC梁进行了静载和落锤冲击试验。作为参考梁，90 MPa高强纤维混凝土（HSFRC）梁与2%的纤维体积分数和普通强度混凝土（NSC）梁没有箍筋和钢纤维也进行了测试。研究结果表明：（1）钢纤维体积分数分别为1%和3.5%时，PFFRC梁的静载承载力可分别提高2倍和3倍以上;（2）纤维掺量为3.5%的PFFRC梁具有最大的抗冲击性能，纤维体积分数为2%的梁性能次之，但差异不大;（3）尽管掺2%纤维的高强钢纤维混凝土梁的静力承载力比掺1%纤维的PFFRC梁的静力承载力小，前者表现出比后者稍大的抗冲击性，因为钢纤维的桥接效应在冲击载荷下比在静态载荷下具有更大的影响。
Ultrahigh-performance fiber-reinforced concrete (UHPFRC) is an advanced cement-based composite material. Its ultrahigh compressive strength and high ductility can enable the downsizing of structural members, with special application to high-rise buildings. These excellent mechanical properties also allow its application in protective structures to resist high-speed penetration, low-velocity impact, and blast loading. UHPFRC with a compressive strength of approximately 150–200 MPa has traditionally been used to investigate the impact resistance of structural members under low-velocity impact loading. Recently, however, porosity-free concrete of the 400 MPa class of compressive strength has been developed. In this paper, to investigate the effects of the concrete strength and the steel fiber volume fraction on the impact resistance of porosity-free fiber-reinforced concrete (PFFRC) members, static and drop-weight impact loading tests were conducted on PFFRC beams by varying the volume fraction of steel fiber from 1 to 3.5%. As reference beams, 90 MPa high-strength fiber-reinforced concrete (HSFRC) beams with a 2% fiber volume fraction and normal-strength concrete (NSC) beams without stirrups and steel fibers were also tested. The results obtained from this study were as follows: (1) the static load-carrying capacity of a PFFRC beam can be enhanced by more than two and three times that of an NSC beam by adding 1 and 3.5% volume fractions of steel fiber, respectively; (2) a PFFRC beam with 3.5% fiber had the greatest impact resistance of all the beams considered in this study, and the beam with 2% fiber volume had the second-greatest performance, but the difference was small; (3) even though an HSFRC beam with 2% fiber had a smaller static load-carrying capacity than a PFFRC beam with 1% fiber, the former exhibited a slightly greater impact resistance than the latter because the bridging effect of the steel fibers has a greater influence under impact loading than under static loading.