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模型试验

对碳纤维布(CFS)加固复合受力的钢筋混凝土箱梁的抗扭性能进行试验研究。设计制作4根矩形钢筋混凝土箱梁模型和1套抗扭试验装置,对其中3根箱梁采用不同方式的CFS加固,并对4根箱梁进行不同弯剪扭复合受力下抗扭性能的模型试验;根据试验结果对比分析加固后箱梁承载力的提高和刚度的变化,从而得出CFS的加固效果;深入研究加固后箱梁纵筋和箍筋的应力变化以及CFS的应变情况,从而得到CFS加固提高箱梁抗扭承载力的工作机理;应用变角度空间桁架模型对箱梁模型的抗扭承载力进行理论计算,并与试验结果进行比较,理论值与试验值符合较好,其比值的平均值为1.076,标准差为0.0692,变异系数为0.0643。最后得出结论,CFS加固能有效地提高弯剪扭复合受力下箱梁的抗扭承载力,利用变角度空间桁架模型能较精确地计算CFS加固的箱梁的抗扭承载力。

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

Experiments on the torsional behavior of carbon fiber sheet (CFS) strengthened reinforced concrete(RC) box beams subjected to combined action of bending-shear-torsion are performed.Four models of rectangular RC box beams,three of which are strengthened with CFS,and a set of test facility for torsional behavior are designed and manufactured,and the model tests on the torsional behavior are performed under different combined actions of bending-shear-torsion.Based on the test results,the strengthening effect of CFS is obtained through the comparison of the improvement of the capacity and the change of the stiffness of the box beams strengthened with CFS.The mechanism to improve the torsional capacity of the box beams is found through thorough investigation on the stresses in the longitudinal bars and the hoops and the strains of CFS of the strengthened box beams.By employing the theory of the variable-angle spatial truss model,the torsional capacity is calculated and compared with the test results,and good agreement is observed:the mean ratio of the calculation to the test values is 1.076,the standard deviation is 0.0692 and the coefficient of variation is 0.0643.It is concluded that the torsional capacity of the CFS strengthened RC box beams subjected to the combined actions can be effectively improved and can be accurately calculated by employing the variable-angle spatial truss model.