基于等效格子梁理论的中等跨径简支钢箱梁应力分析验算

Stress Analysis and Verification of Medium-Span Simply Supported Steel Box Girders Based on Equivalent Grillage Theory

摘要: 为验证中等跨径简支钢箱梁在公路-I级荷载下的结构性能，本文以一座跨径55 m的单箱双室钢箱梁为分析对象，引入等效格子梁理论，分别从主梁整体受力(第一体系)和桥面板局部受力(第二体系)两个层面开展应力校核。借助通用有限元软件建立空间杆系模型，综合考虑结构自重、二期恒载、车辆活载及温度作用等工况，对持久状况正常使用极限状态下的应力水平与竖向挠度进行计算。分析结果显示，钢箱梁关键截面的最大应力值及跨中挠度均控制在规范限值以内，表明等效格子梁理论能够有效指导中等跨径钢箱梁的受力评估。

Abstract: To validate the structural performance of a medium-span simply supported steel box girder under Highway Class I loading, this study takes a 55 m single-box double-cell steel box girder as the analysis object. Based on the equivalent grillage theory, stress checks are carried out at two levels: the global behavior of the main girder (first system) and the local behavior of the deck slab (second system). A spatial frame element model is established using general-purpose finite element software, and various load cases—including structural self-weight, superimposed dead load, vehicle live load, and temperature action—are considered. The stress levels and vertical deflections under the serviceability limit state in the persistent condition are then calculated. The results show that both the maximum stress values at critical sections and the mid-span deflection of the steel box girder fall within the limits specified in the relevant codes, indicating that the equivalent grillage theory can effectively guide the mechanical evaluation of medium-span steel box girders.