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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。
In order to improve the seismic performance of reinforced concrete columns, six reinforced concrete columns with shear-span ratio of 3.0 and fewer stirrups in columns were designed by replacing FRP with ordinary concrete at the lower end of cantilever column. Quasi-static test. The change of FRC height, axial compression ratio, concrete strength and the cracking and failure process of specimens under repeated low-cycle horizontal loading were studied to investigate their hysteresis characteristics and energy dissipation capacity. The results show that, compared with ordinary reinforced concrete columns, the failure mode with partial FRS and fewer stirrup columns is the shear failure after yield bending of longitudinal reinforcement with good deformation capacity and damage tolerance; FRC can reduce the amount of restraint stirrups. Based on the OpenSees analysis platform, the finite element model of cantilever column is established, and the whole process simulation analysis and parameter analysis under repeated horizontal load are carried out. The results show that the calculated value of peak load is slightly smaller than the measured value. The calculated hysteresis curve is in good agreement with the experimental hysteresis curve. In general, the horizontal bearing capacity and Sway angle less affected.