预应力节段拼装式铁路桥墩抗震性能研究

Study of Seismic Performance of Segmental Piers of Railway Bridge

为了解高地震烈度区预应力节段拼装式铁路桥墩的抗震性能,依托和若铁路桥梁工程,采用Abaqus软件建立3个不同墩高(8,12,15 m)典型节段拼装式桥墩的数值模型,分析在静力推覆荷载和循环往复荷载下的力学性能,提出在不同地震作用下界面性能的设防目标,采用动力时程分析验证在地震作用下的安全性和可恢复性,建立桥墩的简化计算模型对界面开裂临界状态的计算公式进行了推导。结果表明:桥墩-承台界面为整个结构的最薄弱界面,界面分离荷载远高于正常使用荷载,在正常使用状态下界面不会出现开裂;双柱墩具有框架效应,桥墩的横桥向抗力远高于顺桥向抗力,顺桥向性能是该桥墩抗震设计的控制因素;在E1地震作用下,桥墩-承台界面不会分离,在E2地震作用下,桥墩-承台界面会轻微分离,但钢绞线仍然保持弹性,震后桥墩-承台界面可以闭合,桥墩可恢复正常使用功能;推导公式计算的桥墩界面开裂荷载与有限元模型值吻合良好,可推广至其它结构形式的预制装配式桥墩。

To investigate the seismic performance of segmental piers of railway bridges in high seismicity area,three finite element models of typical segmental piers with heights of 8 m,12 m and 15 m were established by Abaqus,based on a real bridge of the Hetian-Ruoqiang Railway.Static pushover analysis and cyclic loading analysis were conducted to examine the mechanical properties of the piers,based on which the fortification targets of interface performance under different seismic actions were proposed.And dynamic time-history analysis was carried out to verify the safety and resilience of the piers in seismic events.A simplified model of the pier was built up to calculate the threshold condition of interface cracking,and the calculation formulas were derived.The results show that the pier-pile cap interface is the weakest interface in the whole structure,where the interface separation load was far higher than the common service load,indicating that the interface would not crack in the normal service condition.The double-column pier exhibited framing effect,making the lateral resistance of the pier much higher than the longitudinal resistance,thus the longitudinal performance of the piers controls the seismic design.Under the action of E1 earthquakes,the pier-pile cap interface did not separate.Under the action of E2 earthquakes,the pier-pile cap interface slightly separated,but the steel strands still remained in elastic condition,the seam of the pier-pile cap interface could close,and the pier could restore to normal service condition.The interface cracking loads calculated by the derived equations agreed well with the calculations from finite element model.The proposed equations can be used to analyze the segmental piers in other types of bridge structures.