套筒灌浆缺陷对预制混凝土柱抗震性能影响的试验研究

Experimental study on effect of sleeve grouting defects on seismic behavior of precast concrete columns

针对目前广泛应用的套筒灌浆连接预制混凝土柱,为了研究套筒灌浆缺陷对其抗震性能的影响,设计了7根预制混凝土柱与1根现浇混凝土柱,在预制混凝土柱一侧套筒内预设了“浆体回落”与“完全不灌浆”两类灌浆缺陷,并开展低周往复荷载试验,分析其破坏形态及滞回特性、承载力、耗能能力等抗震性能。结果表明,混凝土柱发生柱底截面破坏与套筒顶截面破坏两种受弯破坏模式。无缺陷预制混凝土柱与现浇混凝土柱的破坏模式相同,承载力相近。与无缺陷预制混凝土柱相比,带缺陷预制混凝土柱的正向峰值荷载降低了6%~44%、位移延性系数降低了1%~43%、累积总耗能值降低了37%~63%。当缺陷高度超过全灌浆套筒一侧钢筋锚固长度的33%时,灌浆缺陷将对预制混凝土柱的滞回特性、承载力、延性与耗能能力等均产生明显不利影响。

In order to experimentally investigate the effects of grouting defects on the seismic behavior of precast concrete columns connected with grouted sleeves,which are widely used at present,a total of seven precast concrete column specimens and one comparison specimen of cast-in-site column were designed.Two types of grouting defects with different sizes,namely‘reflowing of grout’and‘no grouting at all’were preset in one row of sleeves.Low cyclic reversed loading tests were performed to analyze the seismic behavior of the specimens such as failure modes,hysteresis characteristics,load-carrying capacity and energy dissipation capacity.The results show that two flexural failure modes occur to specimens,that is,failure at column bottom section and failure at the section around sleeve top.The failure mode of the intact precast column specimen is the same as that of the cast-in-site column specimen,and the loadcarrying capacity is similar.Compared with the intact precast column specimen,the positive peak load of the precast column specimens with grouting defects is reduced by 6%to 44%,the displacement ductility coefficient is reduced by 1%to 43%,and the total cumulative energy dissipation is reduced by 37%to 63%.The grouting defects with a height exceeding 33%of the anchorage length of steel bar on one side of the full grouting sleeve have large adverse effects on the hysteretic characteristics,load-carrying capacity,ductility and energy dissipation capacity of the precast columns.