现浇ECC和预制榫卯混合连接装配式RC桥墩抗震性能

为提高装配式钢筋混凝土(RC)桥墩的抗震性能，提出采用现浇工程水泥基复合材料(ECC)和预制榫卯混合连接的新型接头构造；开展了3个采用混合接头连接(以现浇ECC段高度与凹槽深度为变化参数，编号为DZ-1、AC-200、XJ-250)和1个采用现浇ECC湿接缝连接(编号为PT-1)的装配式RC桥墩试件的拟静力试验；建立了经试验验证的ABAQUS有限元模型，分析了轴压比、长细比、凹槽深度、现浇ECC段高度等参数对装配式RC桥墩抗震性能的影响。分析结果表明：4个桥墩试件破坏模式均为压弯破坏，且各试件的ECC现浇段均未发生破坏；与PT-1试件相比，现浇ECC和预制榫卯混合连接装配式RC桥墩的峰值荷载增大了25.74%~30.03%，极限位移增大了22.75%~106.39%，残余位移下降了43.70%~61.42%，具有较好的抗震性能；AC-200试件的凹槽深度最大，其残余位移大于其他装配式桥墩，且耗能能力较差；装配式桥墩的峰值荷载和屈服荷载随轴压比、现浇ECC段高度的提高而提高，随着长细比的提高而下降；延性系数随着现浇ECC段高度的提高而提高，随着长细比、轴压比的提高而下降。建议混合连接的凹槽深度不宜超过凸榫边长的75%。

Anti-seismic performance of cast-in-place ECC and prefabricated mortise-tenon hybrid connection assembled RC bridge piers

In order to improve the anti-seismic performance of assembled reinforced concrete (RC) bridge piers, a new connection configuration using a hybrid connection of cast-in-place engineered cementitious composites (ECC) and prefabricated mortise-tenon was proposed. Quasi-static tests of three assembled RC pier specimens using hybrid connections (with the height of cast-in-place ECC segments and depth of the notch as the varying parameters, No. DZ-1, AC-200, and XJ-250) and one assembled RC pier specimen using a cast-in-place ECC wet connection (No. PT-1) were carried out. A test validated ABAQUS finite element model was established, and the effects of parameters such as the axial compression ratio, length-to-slender ratio, depth of notch, and height of cast-in-place ECC segments on the anti-seismic performance of assembled RC bridge piers were analyzed. Analysis results show that the damage modes of the four pier specimens are all compression bending damage, and the cast-in-place ECC segments of each specimen are not damaged. Compared with the PT-1 specimen, the peak loads of assembled RC bridge piers with cast-in-place ECC and prefabricated mortise-tenon hybrid connection increase by 25.74%-30.03%, the ultimate displacement increase by 22.75%-106.39%, and the residual displacement decrease by 43.70%-61.42%, which indicates better anti-seismic performance. The AC-200 specimen has the largest depth of notch, and its residual displacement is larger than that of the other assembled bridge piers, with poorer energy dissipation capacity. The peak load and yield load of assembled bridge piers increase with the axial compression ratio and the height of cast-in-place ECC segments and decrease with the increase in the length-to-slender ratio. The ductility factor increases with the height of the cast-in-place ECC segment and decreases with the increase in the length-to-slender ratio and axial compression ratio. It is recommended that the depth of the notch in hybrid connections should not exceed 75% of the side length of the tenon.