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对4个不同轴压比、配钢率、加载方向的实腹式型钢混凝土十字形柱进行了低周反复加载试验,通过观测试件各阶段的开裂变形及破坏形态,并分析其破坏机理,得到其荷载-位移滞回曲线、骨架曲线、刚度退化、强度衰减、耗能能力及位移延性系数。通过分析试件的位移延性系数,得到影响实腹式型钢混凝土十字形柱延性的主要因素。结果表明,实腹式型钢混凝土十字形柱试件在其剪跨比为3.25时发生弯曲破坏形态;轴压比较高时,试件强度衰减幅值较小,试件达到极限承载力后刚度退化较快,延性降低;配钢率加大,试件极限承载力有较大提高,强度衰减和刚度退化相对平稳;相同条件下,沿45°方向加载的试件极限承载力比沿工程轴加载的试件极限承载力高,且达到极限承载力后刚度退化较快。
Low-cycle repeated loading tests were carried out on four different cross-section columns with different axial compression ratio, steel ratio and loading direction. Through the observation of the deformation and failure modes at each stage of the specimen, the damage mechanism , The load-displacement hysteresis curve, the skeleton curve, the stiffness degradation, the strength attenuation, the energy dissipation capacity and the displacement ductility coefficient are obtained. By analyzing the displacement ductility coefficient of the specimen, the main factors that affect the ductility of the cruciform concrete filled steel reinforced concrete columns are obtained. The results show that the bending failure mode is observed when the cross-section ratio of the concrete-filled steel reinforced concrete cross-section columns is 3.25. When the axial compression ratio is relatively high, the amplitude of specimen strength attenuation is small, and the stiffness decreases after the ultimate bearing capacity And the ductility decreases. With the increase of the steel ratio, the ultimate bearing capacity of the test piece increases greatly, the strength attenuation and stiffness degeneration are relatively stable. Under the same conditions, the ultimate bearing capacity of the test piece loaded in 45 ° direction is higher than that of the test piece loaded along the engineering axis The ultimate bearing capacity of the specimen is high and the stiffness degenerates rapidly after reaching the ultimate bearing capacity.