钢筋超高性能混合钢纤维混凝土梁受剪性能研究

自密实超高性能钢纤维混凝土具有高强、高韧、高流动性和高耐久性的优势,但其抗拉强度仍远低于抗压强度。通过静力加载试验,研究超高性能纤维混凝土梁的抗弯性能,以及配置550 MPa受拉纵筋时超高性能钢纤维混凝土无腹筋梁,在剪跨比分别为2.5、3时的受剪性能。试验梁的钢纤维体积率为2%,其中超细钢纤维和端弯钢纤维以3∶1比例混合,基体混凝土强度大于C100的强度,梁试件采取自密实成型和常温标准养护方法。试验结果表明:与无钢纤维混凝土梁相比,混合钢纤维超高性能混凝土梁的极限荷载和延性得到明显改善。无腹筋梁的初裂荷载提高了25%～180%、裂缝宽度0.2 mm时的荷载提高了73%～183%、极限荷载提高了68%～317%、延性提高了3.2倍～4.4倍。

STUDY ON SHEAR PERFORMANCE OF ULTRA-HIGH PERFORMANCE CONCRETE BEAMS WITH STEEL BAR AND HYBRID STEEL FIBER

Self-compacting ultra-high performance steel fiber reinforced concrete has the advantages in high strength,high toughness,high fluidity and durability.However,its tensile strength is still far below the compressive strength.In this experiment,superfine fiber and end-bend fiber with steel fiber volume ratio of 2% are mixed at a proportion of 3∶1 in the concrete with a matrix strength higher than C100,to be applied into the ultrahigh performance fiber concrete beam of 550 MPa tensile reinforcement.Six beams with shear span ratio of 2.5 and 3 are studied in this experiment through the method of static loading tests.The results show that at compare with beams without fiber,the imitial crack load of ultra-high performance reinforced concrete beams with steel bar and hybrid steel fiber is increased by 25%~180%,the load of 0.2 mm crack width is increased 73%~18%,the ultimate load is increased by 68%~317%,the ductility is increased by 3.2~4.4 times.