碳纤维布加固弯剪扭复合受力的钢筋混凝土箱梁抗扭性能的理论分析

对碳纤维布(CFS)加固的弯剪扭复合受力的钢筋混凝土箱梁的抗扭性能进行理论分析。文中针对4根CFS加固弯剪扭复合受力的钢筋混凝土箱梁的抗扭性能的模型试验,基于修正的斜压场理论,集中考虑剪扭应力相加面的应力分布,并将混凝土软化系数提高25%,建立CFS加固弯剪扭复合受力的钢筋混凝土箱梁的抗扭承载力的计算方法。通过对4根箱梁试件的极限抗扭承载力的理论计算,并将计算结果与模型试验结果进行对比和分析,发现两者符合较好,其比值的平均值为0.9215,标准差为0.0320,变异系数为0.0347;对箱梁试件的试验破坏截面与理论破坏截面位置不一致的现象给出很好的解释;并与其他计算方法所得的计算结果取得一致。最后得出结论:修正的斜压场理论模型概念明确、安全可靠,可以作为CFS加固弯剪扭复合受力的钢筋混凝土箱梁的极限抗扭承载力的设计计算方法。

THEORETICAL ANALYSES ON TORSIONAL BEHAVIOR OF CARBON FIBER SHEET STRENGTHENED RC BOX BEAMS SUBJECTED TO COMBINED ACTION OF BENDING-SHEAR-TORSION

In this paper,theoretical analyses on the torsional behavior of CFS strengthened reinforced concrete(RC) box beams subjected to combined action of bending-shear-torsion are performed.Based on model experiments of CFS strengthened RC box beams,a calculation method for the torsional capacity of CFS strengthened RC box beams subjected to combined action of bending-sheartorsion is constructed by using the modified compression field theory,in which the stress distribution on the additive section of shear-torsion is considered and the softening coefficient of concrete is increased by 25%.Through numerical calculation of the ultimate torsional capacity of the 4 specimens of box beams and comparison with the test results,it is found that the calculation results are almost coincided with the test results,in which the mean ratio of calculation to test results is 0.9215,the standard deviation is 0.0320 and the coefficient of variation is 0.0347.The phenomenon of inconsist positions of the test and the theoretical failure sections is explained,and the agreement the calculation results of other calculation methods is obtained.It is concluded that the modified compression field theory can be employed as the calculation method in design for the torsion capacity of CFS strengthened RC box beams subjected to combined action of bending-shear-torsion.