局部采用纤维增强混凝土柱的抗震性能试验与分析

ExperimentS and analyses of seismic behavior of columnS with fiber-reinforced concrete in bottom region

  • 摘要: 为了提高钢筋混凝土柱的抗震性能,在悬臂柱下端局部采用纤维增强混凝土(FRC)代替普通混凝土,设计了6根剪跨比为3。0、柱内箍筋配置较少的钢筋混凝土柱试件,进行了拟静力试验。通过改变FRC区高度、轴压比、混凝土强度,观测试件在低周反复水平荷载作用下的开裂和破坏过程,研究其滞回特性及耗能能力。结果表明,与普通钢筋混凝土柱相比,局部采用FRC且箍筋配置较少的柱,其破坏形态为纵向钢筋弯曲屈服后的剪切破坏,具有较好的变形能力和损伤容限;局部使用FRC可以减少约束箍筋用量。基于OpenSees分析平台,建立了悬臂柱的有限元模型,对其进行了反复水平荷载作用下的全过程模拟分析和参数分析。分析结果表明:峰值荷载计算值比实测值稍小;计算滞回曲线与试验滞回曲线总体上比较吻合;一般情况下,FRC区高度和柱端体积配箍率对柱的水平承载力和侧移角影响较小。

     

    Abstract: In order to improve the seismic behavior of the reinforced concrete columns,6 reinforced concrete column specimens with fiber-reinforced concrete (FRC) in the bottom region were designed and tested under reversed cyclic lateral loading. The specimens’ shear span ratio was 3 and their amounts of stirrups were relatively few. The height of FRC region,the axial load ratio and the concrete compressive strength were varied. The cracking and damage process of the specimens were observed and the hysteretic behavior and energy dissipation capacity were studied. The results show that,compared with ordinary concrete columns,the column with FRC in bottom region and few stirrups failed in shear after flexural yielding,and they have better ductile characteristics and damage tolerance. The columns with FRC in the bottom region can be designed with a small amount of stirrups. In addition,a finite element model was established to analyze the behavior of the columns under quasi-static cyclic loading in a displacement control mode by the software named OpenSees,and then a parametric analysis was made. Research shows that the peak load of numerical simulation are slightly smaller than that of the test,and the hysteretic curves of numerical simulation are in good agreement with those of the experiments. The parametric analysis shows that the impact of the height of FRC region and the volumetric raito of confinement steel in bottom region on the lateral load-carrying capacity and the lateral displacement is small.

     

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