基于试验验证的部分装配式桥墩抗震性能分析

Analysis on Seismic Performance of Partially Fabricated Pier Based on Experimental Verification

部分装配式桥墩是采用现浇墩底与后张预应力相组合的一种新型装配式桥墩。为研究该新型装配式桥墩的抗震性能,进行了部分装配式桥墩及全装配式桥墩拟得静力加载试验研究。结合拟静力试验加载试验结果,采用Abaqus混凝土塑性损伤本构模型建立了试验桥墩的三维精细化分析模型。通过对比试验-模拟损伤分布及滞回曲线,验证了分析模型的准确性。依据已建立的三维精细化分析模型,进行了部分装配式桥墩拟静力加载试验过程分析,对其主筋、箍筋加载过程应力分布状态、无黏结预应力内力增长模式及部分装配式桥墩变形模式进行了精细化分析。试验及分析结果表明:由于预应力配筋率较低,接缝处受压破坏为该类桥墩的主要破坏形式;在部分装配式桥墩的水平往复荷载作用下,无黏结预应力钢束始终处于弹性状态,未达到屈服状态,其内力增长与加载位移呈线性关系,桥墩具有较好的自复位能力;部分装配式桥墩在水平往复荷载作用下,墩底现浇段主筋应力较大,而墩身预制段主筋应力较小。因此在设计部分装配式桥墩时,现浇墩底应按照延性准则来设计,预制段墩身整体应力水平偏低,可适当降低配筋率。

The partially fabricated pier is a new type of prefabricated pier that combines cast-in-place pier bottom with post-tensioned prestress.In order to study the seismic performance of the new fabricated pier,the static loading experimental research on partially prefabricated pier and fully prefabricated pier is conducted.Based on the result of quasi-static test loading test,a 3D refined analysis model of the experimental pier is established by using Abaqus concrete plastic damage constitutive model,which is verified by comparing experimental and simulation damage distribution and hysteresis curves.Based on the established 3D refined analysis model,the pseudo-static loading test process of partially fabricated pier is analyzed.The stress distribution state of main reinforcement and stirrups during loading,the growth mode of unbonded prestressed internal force and the deformation mode of partially fabricated pier are analyzed in detail.The test and analysis results show that(1)Due to the low prestressed reinforcement ratio,the compression failure at the joints is the main failure form of this type of pier.(2)Under the horizontal reciprocating load on partially prefabricated pier,the unbonded prestressed steel tendon is always in an elastic state and has not reached the yield state,its internal force growth is linearly related to the loading displacement,and the pier has good self-reset ability.(3)Under the horizontal reciprocating load on partially prefabricated pier,the main reinforcement stress of the cast-in-place section at the pier bottom is relatively large,while the main reinforcement stress in precast segment of pier is small.Therefore,when designing partially fabricated piers,the bottom of the cast-in-place pier should be designed in accordance with the ductility criterion.Due to the low overall stress level of the prefabricated pier body,the reinforcement ratio can be appropriately reduced.