采用混合接头的装配式RC圆柱墩轴压极限承载力试验研究

Experimental research on axial ultimate bearing capacity of the assembled RC cylindrical piers with hybrid connection

为研究采用灌浆套筒和钢管剪力键混合接头的装配式钢筋混凝土(reinforced concrete,RC)圆柱墩的轴压性能,设计了4根RC圆柱墩(分别为整体现浇墩柱、灌浆套筒连接墩柱、钢管剪力键连接墩柱、混合连接墩柱),开展圆柱墩的轴压极限承载力试验,对比4根墩柱在破坏模式方面的差异,分析试件的承载能力、变形和应变等变化规律,并结合有限元计算分析装配式桥墩的损伤机理,最后对轴压承载力进行计算。结果表明:在轴压作用下,混合连接装配式桥墩与整体现浇桥墩的破坏形态和受力过程相似,表现为柱中上部混凝土压碎破坏;试验测得的混合连接装配式墩的极限承载力最大,灌浆套筒连接装配式墩、钢管剪力键连接装配式墩的极限承载力分别是混合连接装配式墩的91.5%、79.2%;混合连接装配式墩的受压性能优于其他试验构件,钢管和套筒可以很好地参与受力;混合连接装配式墩在轴压荷载下钢筋先屈服、钢管后屈服,其灌浆套筒最大应变比灌浆套筒连接装配式墩的灌浆套筒应变小且未屈服;按现有规范进行计算,混合连接装配式墩实测承载力和规范计算值误差为22.7%,考虑钢管作用,初步提出修正公式进行计算,实测值和计算值误差为2.7%,计算结果与试验结果较为吻合,可为工程实践提供参考。

In order to study the axial compression performance of fabricated RC cylindrical piers with hybrid connection of grout sleeve and steel pipe shear key, four kinds of RC cylindrical piers(monolithic cast-in-place pier column, grout sleeve connection pier column, steel pipe shear key connection pier column, and hybrid connection pier column) were designed. The axial compression ultimate bearing capacity test of cylindrical piers was carried out, and the differences in failure modes of the 4 piers were compared. The changing laws of the load-bearing capacity, deformation and strain of the specimens were analyzed. Combined with finite element calculation, the damage mechanism of fabricated bridge piers was analyzed, and finally the axial load bearing capacity was calculated. The results show that under the action of axial compression, the failure modes and stress processes of the hybrid connection fabricated pier and the monolithic cast-in-place pier are similar, which are manifested as the crushing failure of the upper part of the column. The ultimate bearing capacity of the hybrid connection fabricated pier measured in the test is the largest, and the ultimate bearing capacities of the grout sleeve connection fabricated pier and the steel pipe shear key connection fabricated pier are 91.5% and 79.2% of the hybrid connection fabricated pier, respectively. The compression performance of the hybrid connection fabricated pier is better than that of other test members, and the steel pipe and sleeve can participate in the force well. Under the axial compression load, the steel bar yields first and the steel pipe yields later in the hybrid connection fabricated pier. The maximum strain of the grouting sleeve of the hybrid connection fabricated pier is smaller than that of the grouting sleeve connected fabricated pier and does not yield. According to the existing specification, the error between the measured bearing capacity of the mixed-connected fabricated pier and the calculated value of the specification is 22.7%. Considering the effect of the steel pipe, a correction formula is preliminarily proposed for calculation, and the error between the measured value and the calculated value is 2.7%. The calculated results are in good agreement with the test results and can provide reference for engineering practice.