混合连接预制装配式桥墩抗震性能研究

Aseismic performance of mixed connection prefabricated bridge pier

针对既有单一形式连接的装配式桥墩难以同时满足中高烈度区轨道快线桥墩对抗弯刚度和多级抗震需求的问题,京雄快线提出了采用无黏结预应力筋、灌浆套筒、混凝土剪力榫及浅承插混合连接的装配式桥墩结构方案。基于室内装配式桥墩足尺模型拟静力试验,建立并验证了精细化数值模型,对比分析了单一连接与混合连接桥墩抗震性能的差异,系统研究了预应力水平、预应力筋位置、灌浆套筒长度及墩底承插深度4个连接参数对桥墩抗震性能的影响规律。结果表明:混合连接装配式桥墩在水平荷载作用下呈典型弯曲破坏,连接性能可靠,抗震性能良好。提升预应力水平可提高桥墩水平承载力,但会降低桥墩变形能力,增大残余位移,预应力水平由30%增加至70%时,承载力提高10.16%。改变预应力筋位置对桥墩抗震性能基本无影响,增大灌浆套筒长度可显著降低桥墩塑性铰长度。墩底承插深度由0.06 D增加至0.18D时,可提高承台对桥墩的侧向约束作用,滞回耗能增加15.87%。为保证混合连接装配式桥墩同时具有良好的自复位和耗能能力,预应力水平不宜大于50%且墩底浅承插深度不宜超过0.12 D。

Here,aiming at the problem of existing prefabricated bridge piers with a single connection form being difficult to simultaneously meet bending stiffness and multi-level aseismic requirements of rail express piers in medium to high seismic intensity zones,a prefabricated bridge pier structure scheme was proposed by Jingxiong Express using non-bonded prestressed reinforcements,grouting sleeves,concrete shear tenons and shallow socket mixed connections.Based on quasi-static tests of a full-scale indoor prefabricated bridge pier model,a refined numerical model was established and validated with tests.Differences of aseismic performances between single connection and mixed connection bridge piers were analyzed contrastively.Effects of 4 connection parameters including prestressed level,prestressed steel bar position,grouted sleeve length and pier bottom socket depth on aseismic performance of bridge pier were systematically studied.The results showed that mixed connection prefabricated bridge pier exhibits typical bending failure under horizontal load,it has reliable connection performance and good aseismic performance;increasing prestressed level can enhance horizontal load-bearing capacity of bridge pier,but reduce its deformation capacity and increase residual displacement,when prestressed level increases from 30%to 70%,pier’s load-bearing capacity increases by 10.16%;changing prestressed steel bar has little effect on aseismic performance of bridge pier,and increasing grouted sleeve length can significantly reduce plastic hinge length of bridge pier;when pier bottom socket depth increases from 0.06 D to 0.18 D,the lateral constraint effect of pier cap on pier can be improved,and hysteresis energy dissipation increases by 15.87%;to ensure mixed connection prefabricated bridge pier having both good self-resetting and energy dissipation capabilities,prestressed level should not exceed 50%and pier bottom shallow socket depth should not exceed 0.12 D.