钢-纤维复合纵筋和玄武岩纤维复合纵筋混凝土梁受剪承载力试验研究

Experimental study on shearing capacity of concrete beams longitudinal reinforced with steel fiber composite bars and BFRP bars

为了研究纵筋分别采用钢-纤维复合筋(SFCB)和玄武岩纤维复合筋(BFRP筋)的混凝土梁受剪性能,以普通钢筋混凝土梁作为对比,设计并开展了46根梁的受剪承载力试验,变化参数为剪跨比、纵筋配筋率和有无箍筋。试验结果表明:三种纵筋梁的受剪承载力均随着剪跨比的减小而增大;SFCB梁的受剪承载力随着纵筋配筋率的增大也增大。此外,提出广义销栓作用影响系数的概念,推导其计算式,用于评价复合纵筋和玄武岩纵筋对混凝土梁受剪承载力的贡献,并据此建立受剪承载力计算式。经与国内外共223组混凝土梁(纵筋为钢筋、BFRP筋和SFCB等)受剪试验数据对比,验证所提广义销栓作用受剪承载力计算式的正确性。在此基础上,采用与钢筋混凝土梁受剪承载力规范公式相近的安全度,建议了适用于纵筋为复合筋和玄武岩筋的混凝土梁受剪承载力设计公式。

To investigate the shearing capacity of concrete beams longitudinally reinforced with steel fiber composite bars(SFCBs)and basalt fiber reinforced plastics(BFRP)bars respectively,shearing capacity tests of 46 specimens were designed and conducted.Beams reinforced with steel bars were also tested for comparison.The experimental parameters include shear span ratio,longitudinal reinforcement ratio and the existing of stirrups.The test results demonstrate that the shearing capacity of beams with each type of longitudinal reinforcement increases with the decrease of shear-to-span ratio.The shearing capacity of SFCB beams increases with longitudinal reinforcement ratio.Further,to evaluate the contribution of longitudinal SFCBs and BFRP bars to the shearing capacity of the concrete beams,the concept of generalized dowel action influence coefficient was put forward and the corresponding calculation formula was derived.Based on the coefficient,a shearing capacity formula for concrete beams with longitudinal SFCBs or BFRP bars was put forward,and the validity of the formula was verified using 223 shear test results of concrete beams reinforced with steel bars,BFRP bars and SFCBs.Further,referring to the safety level of the formulae proposed in codes for the shear capacity of concrete beams reinforced with steel bars,the design formula for the shearing capacity of concrete beams reinforced with SFCBs and BFRP bars was proposed.