碳纤维增强聚合物-圆钢管混凝土的受扭性能

Torsional performance of concrete filled circular carbon fiber reinforced polymer-steel tube

为了研究碳纤维增强聚合物(CFRP)-圆钢管混凝土的扭转性能,进行了18个CFRP-圆钢管混凝土试件的扭转静力试验和有限元分析。试验研究表明:CFRP-圆钢管混凝土典型的扭矩-转角曲线可以对应划分为试件的初始弹性阶段、刚度退化的第二弹性阶段、弹塑性阶段和塑性阶段;试件在经历了较大的变形后仍可以保持较高的承载力,属于延性破坏;随着混凝土强度的提高和CFRP层数的增加,CFRP-圆钢管混凝土承载力和弹性阶段的刚度都有所提高;钢管和CFRP可以协同工作,变形基本符合平截面假定,纵向应变与横向应变均为拉应变。应用ABAQUS模拟了CFRP-圆钢管混凝土扭矩-转角曲线和破坏模态,并且进行了受力全过程分析,模拟和分析结果与试验现象和结果吻合良好。参数分析表明:CFRP-圆钢管混凝土扭矩-转角曲线的形状对参数的变化不敏感;但钢材屈服强度或含钢率的提高可以显著提高受扭承载力,混凝土强度的提高可使承载力有所提高,而CFRP层数的增加仅对承载力贡献;含钢率的提高可以提高CFRP-圆钢管混凝土的刚度。定义了CFRP-圆钢管混凝土的抗扭剪切强度,给出了CFRP-圆钢管混凝土的受扭承载力计算式,计算结果与试验结果吻合良好。

In order to study the torsional behavior of concrete filled circular carbon fiber reinforced polymer(CFRP)-steel tube,a total of 18 concrete filled circular CFRP-steel tubes were tested and analyzed by using finite element method under static torsion.The test results show that the typical torsion-angle curves of concrete filled circular CFRP-steel tube consists of two parts:initial elastic stage and stiffness degradation stage.The stiffness degradation stage can be further divided into three substages,including the second elastic stage,elastic-plasto stage and plastic stage.The specimens can maintain some of load bearing capacity even under large deformation,and therefore the failure mode is the ductile failure.Additionally,with the increase of concrete strength and the number of CFRP layers,the load carrying capacity of specimen,as well as the stiffness in elastic stage,are improved.The steel tube and CFRP can work cooperatively.The deformation of specimens is in line with plane section assumption basically,and both the measured longitudinal strain and transverse strain in tests are positive.The numerical simulations of the whole loading process were carried out by using software ABAQUS.The simulation method was then verified based on the good agreement between numerical and test results.The shape of torsion-angle curve is not sensitive to the change of parameters.Compared with the promotion effect from the increase of concrete strength,the increase of yield strength of steel or steel ratio can provide a higher enhancement to the torsional strength of specimens.While,the CFRP layers has limited contribution to the strength of specimens.Additionally,the stiffness of specimen can be improved by increasing the steel ratio.According to the numerical analysis,the torsional strength of concrete filled circular CFRP-steel tube was defined.The corresponding calculating equation was proposed and verified based on the good agreement between calculated and test results.