井形碳纤维箍筋混凝土梁抗剪承载力试验

针对碳纤维增强复合材料(Carbon Fiber Reinforced Polymer Plastic,CFRP)筋混凝土梁中封闭箍筋难以弯折成型、制作困难的现状,拟采用“井”字形CFRP箍筋承担斜截面剪力。设计了4个不同配箍率的足尺寸混凝土梁,进行4点弯曲静力加载试验,得到了其在不同配箍率下剪弯段的极限承载力及破坏形式,分析了箍筋应力的变化规律。结果表明：配箍率是影响“井”字形CFRP箍筋的混凝土梁抗剪承载力和破坏模式的一个重要指标,配箍率增大时“井”字形CFRP箍筋的混凝土梁的抗剪承载力显著提升,破坏模式从剪压破坏逐渐转为斜压破坏;通过对梁控制截面上箍筋与纵筋交接位置处锚固性能的理论分析,得出了该位置CFRP“井”字形箍筋的锚固粘结力,其值大于相应锚固段的边界剪力,能够满足斜截面受剪承载力的要求。试验和理论分析结果证明了“井”字形CFRP箍筋用于混凝土梁斜截面抗剪的可行性,可促进CFRP筋在混凝土结构中的大量应用。 关键词：“井”字形FRP箍筋; 受剪承载力;混凝土梁;配箍率

Experimental study on shear capacity of carbon fiber hoop concrete beam in well shape

In view of the difficulty in bending and forming closed stirrup in Carbon Fiber Reinforced Polymer Plastic (CFRP) reinforced concrete beams, it is proposed to adopt "well" shaped CFRP stirrup to bear oblique shear. Four full-size concrete beams with different stirrup ratios were designed, and the ultimate bearing capacity and failure forms of the beams under different stirrup ratios were obtained through 4-point flexural static loading tests. The variation of stirrup stress was analyzed. The results show that the stirrup ratio is an important index that affects the shear bearing capacity and failure mode of concrete beams with "well" shaped CFRP stirrups. When the stirrup ratio increases, the shear bearing capacity of concrete beams with "well" shaped CFRP stirrups increases significantly, and the failure mode gradually changes from shear compression failure to oblique compression failure; Through the theoretical analysis of the anchorage performance at the junction of the stirrup and the longitudinal reinforcement on the beam control section, it is concluded that the anchorage bond force of the CFRP "well" shaped stirrup at this location is greater than the boundary shear force of the corresponding anchorage section, which can meet the requirements of the shear bearing capacity of the inclined section. The results of test and theoretical analysis prove the feasibility of "well" shaped CFRP stirrup used for shear resistance of concrete beam oblique section, which can promote the extensive application of CFRP reinforcement in concrete structures.