圆钢管自密实混凝土加固钢筋混凝土柱抗震性能试验研究

Experimental research on seismic performance of circular RC column strengthened with self-compacting concrete filled circular steel tube

通过8个圆钢管自密实混凝土加固钢筋混凝土（RC）柱、1个增大截面法加固RC柱和1个未加固RC原柱的低周反复加载试验,观察各柱的破坏过程,分析了其滞回曲线、骨架曲线、延性、耗能能力、刚度和承载力退化等,并研究了不同加固方式、轴压比、钢管壁厚、后浇混凝土强度对圆钢管自密实混凝土加固RC柱抗震性能的影响。结果表明：采用圆钢管自密实混凝土加固RC柱,加固部分与原柱之间协同工作性能良好,柱的破坏过程和破坏形态与普通钢管混凝土柱相似,滞回曲线饱满,转角延性系数均大于3. 32,各项抗震性能指标均能满足现有的抗震性能要求,且其抗震性能优于增大截面法加固RC柱的抗震性能。在试验设计的参数变化范围内,随着轴压比的增大,圆钢管自密实混凝土加固柱的承载力和耗能能力提高,但延性降低,刚度和承载力退化变快;随着钢管壁厚的增大,圆钢管自密实混凝土加固柱的承载力、延性和耗能能力等都有显著提高,刚度退化变缓;随着后浇混凝土强度的提高,圆钢管自密实混凝土加固柱的承载力提高,但延性明显降低。

Eight circular reinforced concrete （RC） columns strengthened with self-compacting concrete filled circular steel tube （SRC）, one circular RC column strengthened by the enlarging cross-section method （ARC）, and one RC column without strengthening （ERC） were tested under reversed cyclic loading. The failure process was observed and the seismic performance indexes including hysteresis curves, skeleton curves, ductility, energy dissipation, stiffness and bearing capacity degradation were obtained. The effects of different strengthening methods, axial compression ratio, steel tube thickness and self-compacting concrete strength were investigated for SRC, the results show that the strengthening part and the original RC column worked well together; the failure process and failure pattern of the specimens are both similar to those of normal concrete filled steel tubular columns. The hysteretic curves of SRC demonstrates their excellent energy-dissipating capacities, with the rotation ductility coefficients of all SRC specimens being greater than 3.32. The seismic performance indexes of SRC specimens could all meet the requirements of existing seismic standards, and are superior to the corresponding ERC specimen. With the increase of axial compression ratio, the bearing capacity and energy dissipation capacity of SRC specimens are improved, while their ductility decreased, and the degradation of both stiffness and bearing capacity with displacement become rapider. With the increase of steel tube thickness, all the seismic performance indexes of SRC specimens are significantly improved. With the increase of self-compacting concrete strength, the bearing capacity of SRC specimens increases, but the ductility decreases significantly.