节能砌块隐形密框复合墙体双面受火后抗震性能

ASEISMIC PERFORMANCE OF ENERGY-SAVING BLOCK COMPOSITE WALL with INVISIBLE MULTI-RIBBED FRAME AFTER TWO-SIDED FIRE

  • 摘要: 为了研究节能砌块隐形密框复合墙体双面受火后的滞回性能、刚度退化、延性和耗能能力等抗震性能,设计制作了缩尺比例为1/2的6个有抹面墙体试件和6个无抹面墙体对比试件。对6个有抹面试件和3个无抹面试件在ISO-834国际标准升温曲线下进行双面受火试验;对12个试件进行了低周往复加载试验,主要研究了轴压比、受火时间、有无抹面对墙体的骨架曲线及滞回特性的影响。研究结果表明:轴压比相同的试件,受火时间增大,骨架曲线的斜率在减小,受火后的试件较常温试件的峰值荷载值下降,表明火灾会降低复合墙体的抗剪承载力和刚度。有抹面的复合墙体骨架曲线斜率均大于无抹面的复合墙体,且屈服荷载和峰值荷载有明显的上升,在受火时间相同情况下,上升幅度随轴压比增大而减小;相同轴压比情况下,复合墙体的屈服荷载和峰值荷载随受火时间的增加而降低。相同受火时间下(45 min),轴压比增大,屈服荷载和峰值荷载提高。复合墙体0 min~30 min双面受火后的延性系数,随着受火时间的延长而上升;而在30 min~45 min,随着受火时间的延长而下降。受火后复合墙体的延性系数随着轴压比的增加而出现一定的下降,轴压比越大, 构件的延性降低的越多。轴压比相同时,随着受火时间的增加,墙体每级耗散能出现明显的减小;受火时间相同时,随着轴压比的增大,墙体每级耗散能出现明显的减小。在相同的轴压比和受火时间的情况下,无水泥砂浆抹面的墙体单圈耗散能出现明显的减小。研究结果对火灾后节能砌块隐形密框结构的安全性鉴定和修复加固具有十分重要的意义。

     

    Abstract: In order to study the aseismic performance of the energy-saving block and invisible multi-ribbed frame composite wall after two-sided fire in terms of hysteretic behaviors, of stiffness degradation, of ductility, of energy dissipation capacity, and etc., 1/2 scale six specimens of the wall with plastering and six contrast specimens without plastering were fabricated and six specimens with plastering and three specimens without plastering were tested under an ISO-834 standard two-sided fire. Thereafter, these specimens were subjected to an in-plane cyclic load to evaluate their post-fire seismic performance. The influences of axial compression ratio, of fire time, with or without plastering on the skeleton curve and hysteretic characteristics of the walls were mainly considered in the test. Research results show that: for specimens with the same axial compression ratio, the fire time increases, and the slope of the skeleton curve decreases; compared with normal temperature specimens, the peak load value of specimens subjected to fire decreases, indicating that fire will reduce the shear capacity and stiffness of composite walls. The slope of skeleton curve of composite wall with plastering is greater than that of composite wall without plastering, and the yield load and peak load increase significantly. Under the same fire exposure time, the rise amplitude decreases with the increase of axial compression ratio. When the axial compression ratio is the same, the yield load and peak load of the specimens decrease with the increase of the fire time. Under the same fire time (45 min), with the increase of axial compression ratio, the yield load and peak load of the specimen are increased. The ductility coefficient of the composite wall after 0 min-30 min two-sided fire increases with the extension of fire time, and decreases with the extension of fire time at 30 min-45 min. After fire, the ductility coefficient of composite wall decreases with the increase of axial compression ratio. The greater the axial compression ratio, the more the ductility of the component decreases. With the same axial compression ratio, the dissipative energy of each stage of the wall decreases significantly with the increase of the fire time; and the dissipative energy of each stage of the wall decreases obviously with the increase of axial compression ratio when the fire time is the same. Under the same axial compression ratio and fire time, the single-circle dissipation energy of the wall without plastering is obviously reduced. The research results are of a great significance for the safety identification and for the repair and reinforcement of the energy-saving block with an invisible multi-ribbed frame structure after fire.

     

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