纤维增强混凝土对角斜筋小跨高比连梁抗震性能试验研究及受剪承载力分析

Experimental study on seismic behavior and shear capacity of diagonally reinforced fiber-reinforced concrete coupling beams with small span-to-depth ratio

为了改善小跨高比连梁的抗震性能,考虑连梁跨高比和对角斜筋配筋率的影响,在课题组前期试验的基础上,在对角斜筋上增设拉筋,制作3个纤维增强混凝土(FRC)对角斜筋小跨高比连梁试件,对其进行拟静力试验,分析连梁的破坏形态、滞回耗能、刚度退化以及延性等抗震性能。基于试验结果及小跨高比连梁的受剪机理,建立连梁受剪承载力计算公式。结果表明,在小跨高比连梁对角斜筋上增设拉筋之后,跨高比为1.25和1.5的连梁,由原来的剪切破坏变为弯曲剪切破坏,并提高了连梁的延性、抗损伤能力和耗能能力;提出的连梁受剪承载力计算公式的计算值与试验值吻合较好。

In order to improve the seismic performance of coupling beams with small span-to-depth ratio, considering the effect of the span-to-depth ratio and ratio of diagonal reinforcement, lacing wires were added on diagonal bars based on the former experimental results. Three diagonally fiber-reinforced concrete （FRC） coupling beam specimens with small span-to-depth ratio were tested under reversed cyclic lateral loading. The failure mode, hysteresis energy dissipation, stiffness degradation and ductility of the coupling beams were analyzed. The calculation formula of shear capacity was established based on the experimental results and the shear mechanism of coupling beams with small span-to-depth ratio. The results show after the lacing wires are added on the diagonal bars in diagonally reinforced FRC coupling beams with small span-to-depth ratio, the failure modes of coupling beams with span-to-depth ratio of 1.25 and 1.5 change from brittle shear failure to flexural-shear failure. Furthermore, the ductility, damage resistance and energy dissipation capacity are improved. The calculating results of shear capacity agree well with the experimental data, which proves the effectiveness of the proposed formula.