车载和温度场耦合作用下大跨悬索桥钢箱梁疲劳性能及耐久性评估方法

The fatigue damage of steel box girder is hugely harmful for the normal operation and the structural safety of large-span highway bridge, so it is necessary to study the influence rules of vehicle-temperature coupling effect on fatigue performance and durability of steel box girder of large-span suspension bridge. Through the analysis of multi-scale numerical simulation, field test, and the data from structural health monitoring system, the regional distribution characteristics of nonlinear dynamic response of steel box girder under the effect of vehicle load was studied, and the regional distribution of load effect and fatigue sensitive index of orthotropic steel box girder were established. The 3D temperature field model and time-varying relationship model of long-span suspension bridge were explored, and the effect of temperature on the internal force distribution and fatigue property of steel box girder was clarified..Combined with the structure model test of vehicle effect and fatigue test of typical welded details, the influence mechanism of the vehicle-temperature field coupling on fatigue performance of steel box girder was revealed, and the fatigue life evaluation method based on analysis of hot spot stress was established. Combined with the long-term detection data, the probability distribution and statistical characteristics of the vehicle loads and temperature were studied, and the durability evaluation method of steel box girder was put forward from the point of probabilistic fatigue and probabilistic fracture mechanics, which provide a basis for the operation and maintenance decision of domestic long-span suspension bridge.

悬索桥钢箱梁疲劳损伤对于大跨公路桥梁正常运营与结构安全构成巨大的危害，研究车辆-温度耦合作用对大跨悬索桥钢箱梁疲劳性能与耐久性的影响规律很有必要。本项目通过多尺度数值模拟分析、现场测试，并结合结构健康监测系统数据分析，研究车辆荷载作用下大跨悬索桥钢箱梁非线性动力响应区域分布特征，建立正交异性钢箱梁区域振动荷载效应分布和疲劳敏感指标。探索大跨悬索桥钢箱梁三维温度场作用模型以及时变关系模型，阐明温度作用对钢箱梁内力分布及疲劳性能的影响规律。结合车辆作用效应结构模型试验和典型焊接细节疲劳试验，揭示车载和温度场耦合作用对于钢箱梁疲劳性能的影响机理，建立基于热点应力分析的疲劳寿命评定方法。结合长期检测数据，进行车辆荷载和温度概率分布与统计特征研究，从概率疲劳和概率断裂力学角度出发提出钢箱梁耐久性评估方法，为国内大跨悬索桥梁运营养护决策提供依据。

悬索桥钢箱梁疲劳损伤对于大跨公路桥梁运营与结构安全构成巨大的危害。项目通过数值模拟分析、试件试验、现场测试，结合大跨悬索桥结构健康监测系统数据分析，进行了车载和温度场耦合作用下大跨悬索桥钢箱梁疲劳性能及耐久性评估研究。内容包括：（1）进行了交通车辆荷载作用下大跨悬索桥钢箱梁车桥耦合响应与局部振动数值模拟研究，建立了钢箱梁区域振动荷载效应分布模型，提出了钢箱梁动力响应区域敏感性能量指标和疲劳敏感性指标。（2）基于润扬大桥、泰州大桥结构健康监测系统数据，进行了大跨悬索桥钢箱梁服役车辆荷载和温度场作用模型研究。建立了钢箱梁疲劳车辆荷载模型、随机车流模型和交通量增长模型，以及钢箱梁三维温度场模型以及温度时变模型。（3）进行了三维温度场作用以及温度时变作用下钢箱梁内力数值模拟，建立了车辆和温度场耦合作用下钢箱梁典型细节疲劳荷载效应的多尺度分析方法。结合钢箱梁细节系列疲劳试验，提出了焊缝裂纹扩展与寿命评估的无网格数值分析方法。（4）研究了大跨悬索桥钢箱梁运营车辆荷载、服役环境温度等变量的概率分布特性，建立了钢箱梁疲劳荷载效应相关性模型，基于概率断裂力学提出了钢箱梁疲劳寿命预测与耐久性评估方法，编制了有关软件。.本项目工作是大跨悬索桥运营养护管理与监测分析中亟待解决的问题，对于实施合理的经济维修、延长大桥的使用寿命，具有非常重要的意义。