高速铁路大跨度拱桥-轨道系统纵向地震响应分析

Longitudinal seismic response of long-span arch bridge-track system of high-speed railway

  • 摘要: 为研究不同形式大跨度拱桥-轨道系统地震响应,以112 m提篮拱桥、140 m钢箱系杆拱桥、(24+160+24) m系杆拱桥及(52+382+52) m钢箱拱桥4种不同形式的拱桥为例,建立了考虑轨道、吊杆、拱肋、桩土共同作用的精细化有限元模型,揭示地震作用下大跨度拱桥-轨道系统动力特性,探讨地震波、地震强度及视波速对地震响应的影响。研究结果表明:一致激励作用下钢轨应力包络图呈反对称分布,最大值出现在梁端附近,拱脚处拱肋轴力最大;不同频谱特性地震波激励下,系统动力响应存在较大差异;地震强度的变化主要影响梁端附近钢轨应力,对中间梁段影响较小;行波效应对地震响应影响较大,拱肋轴力显著增加,钢轨最大应力相比一致激励下应力增幅达149.2%,跨中处钢轨纵向力大幅增加,可达503.4 MPa;视波速越小,轨道受力越大,且随着视波速的增加,钢轨应力分布逐渐接近一致激励。

     

    Abstract: To analyze the seismic response of different forms of long-span arch bridge-track systems, four different forms of arch bridges, namely 112 m basket handle arch bridge, 140 m steel box tied arch bridge, (24+160+24) m tied arch bridge and (52+382+52) m steel box arch bridge, are used as examples. The study revealed the dynamic characteristics of long-span arch bridge-track systems under seismic action and explored the effects of seismic waves, seismic intensity, and traveling wave speed on the seismic response. The results show that the stress envelope of the rail under seismic uniform excitation is antisymmetrically distributed, with the maximum value appearing near the end of the beam and the maximum axial force of the arch rib at the arch foot. There are large differences in the dynamic characteristics of the system under different spectral characteristics of seismic wave excitation. The change in seismic intensity mainly affects the rail stress near the end of the beam, and has less effect on the middle beam section. The traveling wave effect has a significant impact on the seismic response, with a significant increase in the axial force of the arch rib. The maximum stress in the rail increases by 149.2% compared to the seismic uniform excitation, and the longitudinal force in the rail at the middle of the span increases significantly, up to 503.4 MPa. Furthermore, the stress in the rail is greater when the apparent wave speed is smaller. Similarily, the stress on the rail increases as the traveling wave speed decreases. As the traveling wave speed increases, the stress distribution on the rail gradually approaches that of consistent excitation.

     

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