基于材料延性的高延性混凝土无腹筋梁受剪性能试验研究

INFLUENCE OF MATRIX DUCTILITY ON SHEAR BEHAVIOR OF HIGH DUCTILE FIBER REINFORCED CONCRETE BEAMS

为探讨材料延性对无腹筋梁受剪性能的影响,根据高延性混凝土设计理论,考虑纤维抗拉强度、长径比和纤维掺量等因素的影响,进行了4种不同配合比高延性混凝土(HDC)的力学性能试验,并设计了7个高延性混凝土(HDC)无腹筋梁和2个混凝土(RC)梁对比试件,通过静力试验研究材料延性对无腹筋梁的破坏形态、承载力和剪切变形能力的影响。试验结果表明:1)4组HDC试件分别达到不同的延性要求,其等效弯曲韧性可达砂浆试件的50倍,极限拉应变可达普通混凝土的90倍;2)HDC无腹筋梁的承载力可达RC梁的2.36倍,剪切变形能力可达RC梁的3倍以上,均发生具有一定延性的剪拉破坏;3)除剪跨比和纵筋配筋率外,HDC无腹筋梁的受剪承载力和变形能力均随材料延性的提高而增大,在设计中应予以考虑,并可根据工程实际需要选择相应的材料延性需求。

To study the influence of material ductility on beams without stirrups, 7 high ductile fiber reinforced concrete （HDC） and 2 reinforced concrete beams were designed, considering the tensile strength, length-diameter ratio, volume fraction of fiber and shear-span ratio as variable parameters. The mechanical behavior of 4 different mixture proportions HDC was tested, and the shear failure mode, bearing capacity and deformability were studied during the test of the monotonic loading on mid-span. It is concluded that： 1） 4 different mixture proportions HDC can meet different requirements of ductility, whose equivalent flexural toughness can be 50 times as high as mortar, and the ultimate tensile strain can be 90 times as high as mortar; 2） the shear capacity and deformability of HDC beams without stirrups is 2.36 and 3 times of those of RC beams respectively, whose shear-tensile failure mode has much better ductility; 3） except shear-span and longitudinal ratio, the shear capacity and deformability of HDC beams are increasing with material ductility, which should be considered in designing, and choose a corresponding material ductility according to actual needs in engineering.