FRP筋-钢筋增强ECC-混凝土组合柱抗震性能研究

SEISMIC BEHAVIORS OF HYBRID FRP-STEEL REINFORCED ECC-CONCRETE COMPOSITE COLUMNS

提出一种在塑性铰区域采用高延性纤维增强水泥基复合材料(ECC)替代混凝土来改善FRP筋-钢筋增强混凝土柱抗震性能的新方法。对FRP筋-钢筋增强ECC-混凝土构件进行了低周往复荷载试验,系统地考察了基体材料、筋材种类、轴压比对构件破坏模态、裂缝模式、承载力、残余变形、延性和耗能能力的影响。结果表明,将ECC替代塑性铰区域混凝土能够有效避免FRP筋的受压屈曲,进而显著提升组合柱的抗震性能。与钢筋增强ECC-混凝土组合柱相比,复合筋增强ECC-混凝土组合柱的残余变形明显更小,且屈服后的刚度更高。随着轴压比的增大,构件极限强度升高但变形能力降低。通过有限元参数分析可知,组合柱的承载力和变形能力均随着ECC抗压强度及总配筋率的增大而增大;在总配筋率不变的情况下,FRP筋占比越高,构件的延性越好。

It proposes a novel approach to improve the seismic behavior of hybrid FRP-steel reinforced concrete columns through the employment of high ductile engineered cementitious composites(ECC) in the plastic hinge region. A number of hybrid FRP-steel reinforced ECC-concrete columns were tested under reversed cyclic loading. The influence of matrix type, reinforcement type and axial force ratio on the seismic behaviors of columns in terms of failure mode, crack pattern, load carrying capacity, residual deformation, ductility and energy dissipation capacity were systematically investigated. It is found that the substitution of concrete with ECC in plastic hinge region can efficiently avoid the local buckling of FRP bars and thus significantly improve the seismic performance of the columns. Compared with the steel reinforced ECC-concrete composite column, the hybrid reinforced composite column exhibits evidently lower residual deformation and obviously higher postyielding stiffness. With the increase of axial force ratio, the ultimate strength increases while the deformation capacity decreases. Through finite element parametric analysis, it is found that the ultimate strength and deformation capacity of the composite columns increase with the increase of the ECC compressive strength as well as the total reinforcement ratio;with the total reinforcement ratio remaining unchanged, the higher the area of FRP reinforcement, the better the ductility of the column.