纤维增强混凝土柱抗震性能试验研究及数值模拟

为了改善钢筋混凝土（RC）柱的抗震性能和损伤容限，在柱端局部采用纤维增强混凝土（FRC）代替普通混凝土，考虑轴压比和剪跨比，设计了9根FRC柱以及1根RC对比柱试件。通过拟静力试验，观察试件在低周反复水平荷载作用下的裂缝开展过程和破坏形态，研究其滞回性能、变形和承载能力、耗能能力及刚度退化规律等。结果表明，与RC柱相比，剪跨比为2.0的FRC柱仍为压弯破坏，强度和刚度退化缓慢，具有较好的变形能力、耗能能力和损伤容限；轴压比及剪跨比对FRC柱的变形能力和耗能能力有明显影响；FRC柱仅需配置抗剪箍筋，不必另外配置约束箍筋，即可满足变形和耗能要求。基于OpenSees有限元软件，建立了多组FRC柱的有限元模型，在对有限元模型进行试验验证的基础上，进行参数分析。研究结果表明：模拟滞回曲线与试验滞回曲线总体上比较吻合；剪跨比、轴压比及FRC强度对FRC柱的承载能力均有一定影响。

EXPERIMENTAL STUDY AND NUMERICAL SIMULATION ON THE SEISMIC BEHAVIOR OF FIBER REINFORCED CONCRETE COLUMNS

To improve the seismic performance and damage tolerance of reinforced concrete (RC) columns, fiber reinforced concrete (FRC) was used to replace normal concrete in column end regions. Nine FRC specimens with different axial load ratios and shear span ratios and one RC column for comparison purposes were designed. The crack and failure modes of specimens under low cycle reversed loading were observed. The hysteretic characteristics, deformation capacity, energy dissipation capacity and stiffness degradation trend were also investigated. Test results showed that FRC columns with a shear span ratio of 2.0 was subjected to flexural failure, and the strength and stiffness degraded at a lower rate with a better deformation capacity, energy dissipation capacity and damage tolerance compared with normal concrete columns. The axial load ratio and shear span ratio had a significant effect on deformation capacity and energy dissipation capacity of FRC columns. The FRC columns with only shear resisting stirrups satisfied the deformation and energy dissipated requirements. The finite element model that based on experimental verification for cantilever columns with FRC used in the column end region was established by using the finite element software package OpenSees, and the whole process simulative analysis and parametric analysis were attained. Results showed that the calculated hysterics curves agreed well with experimental hysterics curves, and the shear span ratio, axial load ratio and FRC strength affected the bearing capacity of columns.