钢纤维掺量对R-UHPC矩形梁弯、剪受力性能的影响

Effect of Steel Fibers Content on Bending and Shear Mechanical Performance of R-UHPC Rectangular Beam

钢纤维掺量会影响超高性能混凝土(UHPC)的抗拉、抗压强度等材性,进而影响钢筋UHPC(R-UHPC)矩形梁的受弯、受剪性能.开展纤维掺量对R-UHPC梁抗弯、抗剪极限承载力的影响分析.结果表明,随纤维掺量的提高,R-UHPC梁的抗弯、抗剪承载力均相应提高.但由于钢纤维对抗弯、抗剪极限承载力的贡献量不同,提高的作用也不同.钢纤维掺量对R-UHPC梁抗弯承载力的影响远小于它对抗剪承载力的影响.对于R-UHPC矩形梁,存在一个临界的钢纤维掺量.当钢纤维掺量小于此值时,梁将受剪破坏,反之,将受弯破坏;临界钢纤维掺量附近的R-UHPC梁则可能发生弯剪复合破坏.此外,钢纤维掺量还会影响矩形梁的斜裂缝开裂荷载.

The steel fiber content will affect the tensile and compressive strength of ultra-high performance concrete(UHPC),and will further affect the bending and shear mechanical behaviors of reinforced UHPC(R-UHPC)rectangular beams.The effect is analyzed in this paper.The analysis results show that the bending and shear bearing capacity of R-UHPC beams will increase with the increase of fiber content.But due to the different contribution of steel fiber to the bending and shear bearing capacity,the improvement effect on them is different.The effect on the bending bearing capacity of R-UHPC beam is much smaller than that of its shear bearing capacity.There is a threshold of steel fiber content in R-UHPC short beams.For beams with a fiber content smaller than it,they may failure by shear force,otherwise,they may failure by bending moment,while for beams with a fiber content near the threshold,the beams may failure by a mixed shear-flexural failure mode.Moreover,the fiber content also affects the cracking load of initial diagonal crack in rectangular beam.