高温喷水冷却后方钢管再生混凝土短柱轴压性能试验研究

Experimental study on axial compression performance of recycled concrete filled square steel tube short column after exposure to high temperature and water cooling

为研究高温喷水冷却后方钢管再生混凝土的受力机理,设计了27个方钢管再生混凝土试件在高温喷水冷却后进行轴心受压加载试验。试验考虑的变化参数包括再生粗骨料取代率、历经最高温度和冷却方式。本文对试验的过程进行了简要的说明,观察了试件受力破坏的全过程,获取了荷载-位移曲线,峰值荷载并分析了特征点数据以及各变化参数对高温喷水冷却后方钢管再生混凝土短柱轴压性能的影响规律。试验结果表明:历经最高温度越高,试件破坏后核心混凝土的受损程度越严重。随着历经最高温度的不断提高,峰值荷载和轴压刚度整体呈下降趋势,温度在800℃时试件的延性最好,高温使得试件的耗能能力提高;随着再生粗骨料取代率的增加,峰值荷载的变化规律不明显,但取代率为75%的试件具有最高的峰值荷载,轴压刚度呈波动变化,取代率对延性影响较明显,对耗能影响较小;不同冷却方式对方钢管再生混凝土短柱的延性影响较大,对其它力学性能影响不显著。引入材料强度折减系数后,我国DBJ 13-51-2003规程和日本AIJ规程中计算方法可以较好地评估高温喷水冷却后方钢管再生混凝土短柱的轴心受压承载力。

In order to study the bearing capacity of recycled concrete-filled square steel tube(RCFSST)short columns after exposure to high temperature and water cooling,27 RCFSST short columns are designed for axial compression test with the variable parameters of recycled coarse aggregate replacement percentage,temperature and cooling method considered.In this paper,the process of the test was briefly described,mechanical failure pattern of specimens were observed,and the load-displacement curves with the characteristic point parameters on them were obtained,further more,the influence of change factors on the mechanical behavior of RCFSST specimens was analyzed.The results show that the higher the constant temperature is,the more serious the damage degree of core concrete is.With the exposed temperature increasing,the peak load and axial compression stiffness decreases.The ductility of the specimens is the best at 800℃,and the energy dissipation capacity of specimen increases after exposure to high temperature.With the increase of the replacement percentage of the recycled coarse aggregate,the variation of the peak load is not obvious,but the specimen with replacement percentage of 75%has the highest peak load,and the axial compression stiffness fluctuates,the replacement percentage has obvious influence on ductility and less impact on energy dissipation.Different cooling modes have great influence on the ductility of RCFSST short columns,but have no significant effect on other mechanical properties.The results also indicate that the calculation results using the code of DBJ 13-51-2003 and AIJ can better evaluate the axial compression bearing capacity of RCFSST short columns after exposure to high temperature and water cooling.