翼缘尺寸对地聚物混凝土T形梁抗剪性能的影响

Effect of Flange Size on Shear Behavior of Geopolymer Concrete T-Beams

为探究翼缘尺寸对地聚物混凝土T形梁抗剪性能的影响,对1根普通混凝土和4根不同翼缘尺寸的地聚物混凝土T形梁进行了集中荷载下的抗剪试验;试验获得了T形梁试件的承载力、挠度、钢筋应变、破坏模式及裂缝的开展等相关参数。研究结果表明:地聚物混凝土T形梁具有与普通混凝土T形梁相似的裂缝扩展、破坏模式及抗剪承载力,但其刚度和斜截面开裂荷载较低,跨中纵筋和箍筋的应变较大;将翼缘厚度与截面有效高度比值从0.24增大到0.48时,地聚物混凝土T形梁的刚度增大、跨中纵筋应变减小,抗剪承载力提高了12.7%,地聚物混凝土的归一化抗剪强度增大了25.3%;当翼缘宽度超过两倍腹板宽度时,继续增大能减小跨中纵筋应变,但地聚物混凝土T形梁的刚度、抗剪承载力及地聚物混凝土归一化抗剪强度不再增大。规范ACI 318—19和Eurocode 2的计算结果明显低估了地聚物混凝土T形梁的抗剪承载力,GB 50010—2010较接近试验值。为更好预测地聚物混凝土T形梁的计算抗剪承载力,建议在抗剪承载力计算公式中增加翼缘有效受剪面积所提供的剪力。

To investigate the effect of flange size on the shear behavior of geopolymer concrete T-beams,the shear test under concentrated loading was performed on 1 conventional reinforced concrete(RC)and 4 geopolymer concrete(GC)T-beams with different flange sizes.The relative parameters of T-beam specimens such as the load-carrying capacity,deflection,rebar strains,failure mode and crack propagation were obtained by the test.The research results indicate that the GC T-beam has similar crack propagation,failure mode and shear capacity to the RC T-beam,but its stiffness and diagonal section cracking load are lower,and the strain of longitudinal bars and stirrups in the mid span is larger.By increasing the ratio of flange thickness to effective height of the cross-section from 0.24 to 0.48,the stiffness of GC T-beam increases,the strain of the longitudinal bars in the mid span decreases,and the shear capacity increases by 12.7%.The normalized shear behavior strength of geopolymer concrete increases by 25.3%.When the flange width exceeds twice the web width,the continuous increase of the flange width can reduce the strain of the longitudinal bars in the mid span,but the stiffness,shear capacity,and the normalized shear behavior strength of geopolymer concrete will no longer increase.The calculation results of design code ACI 318-19 and Eurocode 2 significantly underestimate the shear capacity of the GC T-beams,and those of GB50010-2010 are close to the test values.To better predict the shear capacity of GC T-beam,it is recommended to increase the shear force provided by the effective shear area of the flange in the calculation formula of shear capacity.