截面退化影响下人字形三角桁拱桥地震响应及安全性能分析

Seismic Response and Safety Performance of Herringbone Triangular Truss Arch Bridge under Section Degradation

摘要: 人字形三角桁拱桥具有独特的空间受力特点，在长期服役过程中易受到环境侵蚀、疲劳作用以及材料性能退化等因素影响，导致构件截面损失和结构刚度下降，进而影响桥梁抗震性能。为研究截面退化对人字形三角桁拱桥地震响应及安全储备的影响，本文以某人字形三角桁拱桥为研究对象，基于Abaqus建立三维有限元模型，采用B31空间梁单元模拟主要承载构件，通过截面尺寸等效削弱方法建立未退化基准模型(A00)和截面退化模型(A10)，开展静力分析及非线性动力时程分析。结果表明：截面退化会降低结构整体刚度，使自重作用下A10模型最大位移由24.54 mm增加至29.02 mm，较A00模型增加18.26%。在7组地震波输入条件下，A10模型平均最大位移达到46.78 mm，相比A00模型增加77.73%，表现出明显的动力响应放大效应。在0.10g地震输入水平下，A10模型最大Mises应力为80.01 MPa，低于Q235钢材屈服强度235 MPa，且未出现塑性应变累积，结构仍保持弹性工作状态。研究结果表明，截面退化会显著降低结构抗震性能储备，但在轻度退化条件下结构仍具有一定安全裕度，可为服役期人字形三角桁拱桥抗震性能评价提供参考。

Abstract: The herringbone triangular truss arch bridge exhibits unique spatial load-bearing characteristics. During long-term service, it is susceptible to environmental corrosion, fatigue effects, and material property degradation, which lead to sectional loss of members and reduction in structural stiffness, thereby impairing the seismic performance of the bridge. To investigate the influence of section degradation on the seismic response and safety margin of such bridges, this study takes a herringbone triangular truss arch bridge as the research object. A three-dimensional finite element model is established using Abaqus, with major load-bearing components simulated by B31 spatial beam elements. An equivalent section‑size reduction method is adopted to create an undegraded baseline model (A00) and a section‑degraded model (A10). Both static analysis and nonlinear dynamic time‑history analysis are carried out. The results indicate that section degradation reduces the overall structural stiffness. Under self‑weight, the maximum displacement of Model A10 increases from 24.54 mm to 29.02 mm, representing an 18.26% increase compared with Model A00. Under seven sets of earthquake ground motions, the average maximum displacement of Model A10 reaches 46.78 mm, which is 77.73% higher than that of Model A00, demonstrating a significant dynamic response amplification effect. At an input seismic acceleration of 0.10g, the maximum Mises stress in Model A10 is 80.01 MPa, which is below the yield strength (235 MPa) of Q235 steel, and no plastic strain accumulation is observed, indicating that the structure remains in the elastic state. The findings suggest that section degradation can substantially lower the seismic performance reserve, but the structure still retains a certain safety margin under mild degradation conditions. This study may provide a reference for the seismic performance evaluation of in‑service herringbone triangular truss arch bridges.