掺入不同尺寸钢纤维的高强混凝土深梁抗剪性能

Shear Behavior of Steel Fiber Reinforced High-Strength Concrete Deep Beams

高强混凝土与不同尺寸钢纤维的混合使用,可以极大的提升材料本身的性能,得到高强度、高韧性的深梁构件。本文对1个高强混凝土深梁和4个掺入不同尺寸钢纤维(混合钢纤维)的高强混凝土深梁进行了受剪试验,通过改变混合钢纤维体积掺量和分布钢筋配筋率,研究了构件的破坏模式、承载能力、变形能力和钢筋应变,分析了混合钢纤维对试件的增强机理。试验结果表明:由于混合钢纤维的存在,试件的承载能力和变形能力得到了大幅提高,后期承载力和刚度下降减缓;试件的承载能力随着混合钢纤维含量和分布钢筋配筋率的增大而增大;试件的变形能力随混合钢纤维含量的增大而增大,但其随分布钢筋配筋率的增大呈先增大后轻微降低的趋势;短钢纤维主要起到对混凝土基体的增强作用,抑制裂缝的出现,长钢纤维主要延缓裂缝的扩展,传递并承担裂缝处的剪力,缓解抗剪钢筋的应力,两种钢纤维在试件加载过程中协同工作。在考虑两种不同尺度的钢纤维协同工作效应的条件下,对混合钢纤维高强混凝土深梁的抗剪承载力计算方法进行了改进,计算结果与试验结果吻合较好。

The combination of high-strength concrete and steel fibers with different sizes can improve the performance of concrete deep beam,such as bearing capacity and toughness.In this paper,shear tests were carried out on one reinforced high-strength concrete deep beam and four hybrid steel fiber reinforced high-strength concrete deep beams.Through changing the volume of hybrid steel fiber and the distribution of web reinforcement,the failure mode,bearing capacity,deformation capacity,and reinforcement strain of specimens were studied.The enhancement mechanism of hybrid steel fiber for specimens was analyzed.The study results show that because of the hybrid steel fiber,the bearing capacity and deformation capacity of specimens are significantly improved,and the stiffness and bearing capacity decrease slowly in the later stage.The bearing capacity of specimens increases with the increase of the volume of hybrid steel fiber and web reinforcement ratio.The deformation capacity of specimens increased with the increase in the volume of hybrid steel fiber,but it increases first and then slightly decreases with the increase of the web reinforcement ratio.The short steel fiber's function is to reinforce the concrete base-body and inhibit the forming of cracks.The long steel fiber's role is to delay the development of cracks,transmit and bear the shear force at the cracks,and relieved the tensile stress of steel bars.Two kinds of steel fibers work together in the loading process of specimens.In addition,the calculation method to predict the shear capacity of hybrid steel fiber reinforced high-strength concrete deep beams was revised,with the consideration of synergistic effect of the two types of steel fibers.The calculated results were in good agreement with the test results.