基于SLGM和T-LSIS的大跨混凝土箱梁桥裂缝统一识别与开裂机理研究  

Unified identification andcracking mechanism research of cracks in long-span concrete box girder bridges using SLGM and T-LSIS

作　　者：徐栋[1] 贾勤龙 端木祥永 Xu Dong;Jia Qinlong;Duanmu Xiangyong(Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学,上海200092

出　　处：《土木工程学报》2025年第2期33-49,共17页China Civil Engineering Journal

基　　金：国家自然科学基金(52078363,51178335)。

摘　　要：持续下挠是大跨混凝土箱梁桥的主要病害特征。由于箱梁的空间复杂性,近年来一些无法由传统分析方法解释的裂缝不断从对桥梁的检查中被发现,不能排除正是由于这些未被注意到的裂缝导致结构的下挠。而对这些超出设计预期的裂缝进行识别与机理研究对传统理论分析框架提出挑战。为解决这一问题,文章提出一种基于精细有限元模型-空间网格模型(SLGM),结合三层应力指标系统(T-LSIS)的裂缝统一识别理论分析框架,并以大跨径混凝土多箱室箱梁桥为实际背景,开展全面的裂缝识别与开裂机理研究。研究考虑不同荷载因素、环境温度场模式、箱梁“框架效应”对结构抗裂性能的影响,并将识别的裂缝位置及形态与现场实测数据进行了对比,讨论并解析实桥不同裂缝的开裂机理及其核心影响因素。结果表明:基于SLGM和T-LSIS分析框架能够实现对实桥裂缝位置和形态的统一识别,包括传统方法无法解释的一些裂缝。此外,内外温差效应对箱梁的抗裂性能影响显著,对“框架效应”的忽略是导致箱梁腹板产生超出设计预期的开裂的核心原因。Continuous deflection is a major defect of long-span concrete box girder bridges.Owing to the spatial complexity of box girders,in recent years,several crack patterns incapable of being explained by conventional analysis methods have been discovered increasingly during bridge inspections.It cannot be ruled out that the deflection of the structure is caused by these unnoticed cracks.However,the identification and mechanism study of these cracks,which exceed the design expectations,pose a challenge to the traditionally theoretical analysis framework.To address this issue,a theoretical analysis framework is proposed for unified crack identification based on a refined finite element model-the Spatial Lattice Grid Model(SLGM),in conjunction with the Three-Layer Stress Indicator System(T-LSIS).Furthermore,a comprehensive investigation of crack identification and cracking fracture mechanisms was conducted using a large-span concrete multi-chamber box girder bridge as the practical background.The impact of various load factors,environmental temperature field modes,and the“frame effect”of the box girder on the structural crack resistance performance were studied.Furthermore,the identified crack locations and morphologies from numerical analysis were compared with filed measurement data,and the fracture mechanisms and key influencing factors of different cracks in the actual bridge are discussed and analyzed.The results demonstrate that the SLGM and T-LSIS analysis framework allows for the unified identification of crack locations and morphologies in the actual bridge,including cracks that conventional methods fail to interpret.Additionally,the differential effect of temperature significantly influences the crack resistance of the entire box girder.The neglection of the“frame effect”is a core reason for the unexpected cracking of the box girder's web beyond the design expectations.

关 键 词：桥梁工程 混凝土箱梁 精细有限元 裂缝识别 空间网格模型 横向框架效应 

分 类 号：U445.71[建筑科学—桥梁与隧道工程]