钢筋混凝土高墩多水准抗震性能试验研究

Experimental Investigation on Seismic Performance of Tall RC Bridge Piers

摘要:

对4个钢筋混凝土箱形高墩模型开展了拟静力试验研究,并重点研究结构在不同损伤状态下的性能及相应的变形指标。采用夹式引伸计监测了裂缝开展全过程,指出采用卸载至位移零点时的裂缝宽度会严重低估结构的残余裂缝损伤,同时允许震后结构产生不需要修复的残余裂缝比完全基于弹性响应可以多出10%～30%的强度折减空间。试验中还观测了混凝土压溃、严重剥落等损伤,并基于PEER数据库等相关试验结果进行了对比验证,结果表明发生混凝土压溃时的各样本墩顶偏移率分布较为集中,约为2.39%,试验结果与样本统计结果符合较好。各试件的最终破坏均表现为纵筋断裂,分别采用Priestley和Berry的等效塑性铰长度计算公式进行了对比,结果表明Berry公式对高墩极限位移的符合性相对较好。

关键词:钢筋混凝土;高墩;抗震性能;残余裂缝;偏移率

Abstract:

Four tall reinforced concrete columns with box section were tested in static cycle loadings and multi-level performance was investigated. The entire progression of cracking was monitored by using clip-on gage and then residual cracking damage was explored. It shows that cracks measured after the specimen was totally re-centered following a displacement cycle would substantially underestimate residual crack damage. An extra discount on the strength demand could be obtained if allowing a tiny residual crack that requires no repair work. Concrete crushing and spalling were also investigated in the test, and similiar experimental results were selected from the PEER datebase and also from some literatures. The samples showed a well concentrated distribution in lateral drifts at the onset of concrete crushing, about 2.39 percent on average, which is quite consistent with the present tests. Finally, all the specimens were found failed from fracture of the longitudinal reinforcement. The equations proposed by Prestely and by Berry were compared in predicting of the ultimate displacement capacity, and the results show that the equation presented by Berry yielded better results for the specimens.

Key words:reinforced concrete; tall columns; seismic performance; residual crack; drift ratio