钢筋ECC/混凝土复合梁斜截面受剪性能试验研究

Experimental study on shear performance of inclined section of reinforced ECC/concrete composite beams

基于钢筋ECC/混凝土复合梁的三点弯曲加载试验,主要研究剪跨比、ECC层厚度和配箍率对复合梁受剪性能的影响,研究结果表明,与RC梁相比,当采用同体积同强度的ECC材料替换梁中部分混凝土,复合梁的极限承载力与抗剪延性均明显提高;ECC层的存在还可有效抑制复合梁斜裂缝的开展,并延缓梁内箍筋屈服,且随着ECC层厚度的增大,复合梁的承载力和延性越大;剪跨比依然是决定复合梁破坏形态的关键因素,由于PVA纤维的桥接承拉作用,配箍率较大且ECC层较厚的复合梁,发生剪压破坏时其箍筋更不易屈服。

Based on the three-point bending test of ECC/concrete composite beams,the influence of shear span ratio,the thickness of ECC layers and stirrup ratio on shear performance of composite beams were studied.The experimental results indicate that compared with the RC beams,the ultimate bearing capacity and shear ductility of composite beams are all increased when the tension zone of concrete is partly replaced by ECC with the same volume and strength.The ECC layer can inhibit the extension of diagonal cracks effectively and delay the yielding of stirrups.With the increasing of the thickness of ECC layer,the bearing capacity and ductility of composite beams increase.Shear span ratio still is the key factor influencing the failure pattern of composite beams.When the shear compression failure happens,stirrups are less likely to yield for the composite beams with larger stirrup ratio and ECC thickness,which is owing to the bridging effect of PVA fiber.