再生粗骨料混凝土柱耐火性能试验与理论分析

为研究再生粗骨料混凝土柱的耐火性能,进行了1个足尺的再生粗骨料混凝土柱和足尺的1个普通混凝土柱在竖向恒定荷载和温度场耦合作用下的耐火性能试验研究,2个试件的混凝土设计强度均为C30,2个柱采用相同的轴压比施加竖向荷载。在试验研究基础上,比较分析了2个试件的耐火极限以及各个测点的温度变化、侧向挠度、轴向变形和破坏过程;用有限元软件ABAQUS对试件截面温度场进行了模拟分析,测点温度增量模拟结果与实测温度增量符合较好。研究表明:相同初始轴压比条件下,混凝土强度接近的再生粗骨料混凝土柱比普通混凝土柱升温速度慢,具有相对较好的隔热性能;再生粗骨料混凝土柱比普通混凝土柱的抗爆裂性能好,耐火极限长;因再生粗骨料混凝土柱比普通混凝土柱的孔隙率相对较高,在高温作用下其内部蒸汽应力可得到一定释放,由此引起的柱子轴向压缩变形相应也较大;一定条件下的再生粗骨料混凝土柱可用于建筑工程。

Experiment and theoretical analysis of fire resistant performance of recycled coarse aggregate concrete columns

In order to ascertain the fire resistance performance of recycled concrete,two full-sized concrete columns were designed and tested at high temperature and unvariable vertical load.One specimen was made from normal concrete C30,the other was made from the recycled coarse aggregate concrete C30.The axial force ratio of the 2 specimens was the same.Based on the experimental studies,aspects,including fire endurance,temperature change,lateral deflection,axial deformation,and failure modes of specimens,were compared and analyzed.The simulation results in ABAQUS show that temperature field of the specimens’cross section agreed quite well with those from the above experiments,and the coarse aggregate concrete column has lower heating rate,higher fire resistance performance,better anti-implosion performance and longer fire endurance compared with the normal concrete column.The reason is that higher porosity in recycled coarse aggregate concrete can release some inner steam stress in high tempreture,and result in larger axial compression deformation.So recycled coarse aggregate concrete can be applied to the building construction under some condition.