小跨高比钢纤维高强混凝土连梁延性和耗能研究

基于9根小跨高比(l/h≤2.5)钢纤维高强混凝土连梁和4根高强混凝土对比连梁试验,考察了跨高比、钢纤维体积掺率和配箍率对高强混凝土连梁位移延性和耗能能力的影响.结果表明:随着跨高比、钢纤维体积掺率和配箍率的增大,连梁的位移延性和耗能性能得到明显改善.当配箍率提高到一定程度后,由于剪压区混凝土破碎引起剪切滑移坡坏,箍筋不能完全发挥作用,配箍率对连梁的延性和耗能能力的影响不再明显.而在按非抗震要求配置箍筋的高强混凝土连梁中掺入ρf=1.0%的钢纤维,可使连梁达到与按抗震要求配置箍筋的连梁相当的位移延性系数,而当ρf=1.5%时,试件发生了弯曲破坏,从根本上改变了小跨高比高强混凝土连梁破坏的脆性性质.

Ductility and energy dissipation capacity of steel fiber reinforced high-strength concrete coupling beams of small span/depth

On the basis of the experiment of 9 steel fiber reinforced high-strength concrete coupling beams of small span/depth (l/h≤ 2. 5) and 4 control coupling beams, the effects of span/depth, steel fiber volume fraction and stirrup content on ductility and energy dissipation capacity of high-strength concrete coupling beams were investigated. The test results show that increasing span/depth, steel fiber volume fraction and stirrup content can improve the ductility and the energy dissipation capacity of coupling beams evidently. When the stirrup content goes beyond a certain value, a shear slippage failure occurs due to the crumbling and spalling of concrete in compressive-shear region of coupling beams, and the effect of stirrup content on coupling beam is not obvious. Whereas, adding ρ_f= 1. 0% steel fibers to a nonseismic coupling beam can achieve an equivalent displacement ductility ratio to that of seismic designed one. And a further increase of ρ_f to 1. 5% can change the failure type of a coupling beam from a brittle shear failure to a ductile flexural failure essentially.