铁路双肢薄壁墩连续刚构桥延性抗震设计

Seismic Ductility Design of Continuous Rigid Frame Bridge with Double-limb Thin-walled Piers on the Railway

文章以某铁路(50+85+50)m双肢薄壁墩连续刚构桥为例,建立基于分布式纤维铰的弹塑性有限元模型,分别考虑纵向和横向地震波输入,进行罕遇地震作用下的非线性时程分析及延性抗震设计。结果表明,在纵向地震下,主墩墩顶及墩底均屈服;在横向地震下,主墩墩顶未屈服而墩底屈服。桥墩非线性位移延性比、桥墩抗剪能力均满足规范要求。但在纵向地震下,梁端位移较大,连续梁与相邻简支梁的梁端之间的梁缝宽度略显不足,需采取措施防止连续梁与相邻简支梁直接碰撞而导致梁体破损。

Taking a continuous rigid frame bridge( 50 + 85 +50) m with double-limb thin-walled piers on the railway as an example, this paper establishes an elastic-plastic finite element model based on distributed fiber hinges, considering the input of longitudinal and transverse seismic waves respectively to carry out nonlinear time-history analysis and seismic ductility design under the action of rare earthquake.The results show that under the longitudinal earthquake, the top and bottom of the main pier yield;under the transverse earthquake, the top of the main pier does not yield while the bottom of the pier yields. The nonlinear displacement ductility ratio and shear capacity of bridge piers all meet the specification requirements. However, under the longitudinal earthquake, the beam end displacement is large, and the beam gap width between the beam ends of the continuous beam and the adjacent simply supported beam is slightly insufficient. It is necessary to take measures to prevent the direct collision of the continuous beam and the adjacent simply supported beam leading to the damage of the beam.