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为研究高温下混凝土短柱的持荷和端部轴向约束对受火后混凝土短柱抗震性能的影响,进行了10根受火1 h后混凝土短柱和2根未受火对比柱的拟静力试验,分析了轴向约束、持荷、轴压比和剪跨比等因素对受火后混凝土短柱的破坏形态、峰值荷载、延性和耗能的影响。结果表明:高温下未持荷短柱、高温下持荷短柱和高温下轴向约束短柱受火1 h后峰值荷载均显著降低,是未受火时的67.7%~75.3%。高温下初始轴压比为0.2时,高温下轴向约束短柱、高温下持荷短柱的高温后峰值荷载分别为高温下未持荷短柱的92.0%~99.9%、99.5%~102.2%。随着轴压比的增大,高温下轴向约束混凝土短柱的附加轴压力减小,高温后受剪承载力增大。当受火时间不超过1 h且轴压比不超过0.3时,受火后混凝土短柱的受剪承载力评定可不考虑高温下持荷和轴向约束的影响。
In order to study the influence of the concrete short columns' holding and end axial restraint on the seismic behavior of post-fire concrete short columns under high temperature, ten concrete short columns and two non-fire contrast columns Static test, the influence of axial restraint, holding load, axial compression ratio and shear span ratio on the failure mode, peak load, ductility and energy dissipation of concrete short columns after fire were analyzed. The results show that the peak loads of unloaded stub columns under high temperature, stub columns under high temperature and axially restrained stub columns under high temperature are significantly reduced after 1 h of fire, respectively, which are 67.7% -75.3% of unloaded beams. Under the condition of initial axial compression ratio of 0.2 and high temperature, the peak load of short column under high temperature and high temperature is respectively 92.0% -99.9% and 99.5% -102.2% . With the increase of axial pressure ratio, the additional axial pressure of the axially confined concrete short column decreases at high temperature, and the shear capacity increases after high temperature. When the fire time does not exceed 1 h and the axial compression ratio does not exceed 0.3, the assessment of shear strength of concrete short columns subject to fire may not consider the influence of the load and axial restraint under high temperature.