Temperature-induced structural static responses of a long-span steel box girder suspension bridge

Abstract

Temperature is a significant load on bridges, particularly for long-span steel box girder bridges. This study investigates the temperature-induced static responses of a long-span suspension bridge under real service environmental conditions using numerical simulations and field measurements. Detailed 2D finite element (FE) models of a typical section for the box girder, main cable, hanger, tower column, and crossbeam are constructed. The thermal boundary conditions are determined strictly according to the surrounding environments of a typical sunny day and applied to the FE models. A transient heat-transfer analysis is performed and the time-dependent temperature and its distribution on the bridge are obtained. In addition, a fine, 3D FE model of the bridge is developed for a structural analysis. The calculated temperatures are applied to the 3D model and the temperature-induced structural responses are simulated. The simulated temperatures and the associated static responses have good agreement with the measured counterparts and support the numerical simulation method. The main cable and bridge deck make the greatest contributions to the temperature effects on the suspension bridge. The static responses of bridge caused by the design vehicle load are also calculated. The daily variation of the temperature-induced static responses is comparable with, even higher than, that of the design vehicle load. 目的: 温度对大跨度桥梁的力学性能影响显著。针对大 跨度钢箱梁悬索桥,本文采用数值方法分析日温 度变化引起的结构静力响应,对比设计车荷载, 以评估温度静力效应的影响。 创新点: 1. 基于数值方法对比大跨度悬索桥温度静力效应 与设计车荷载效应,评估温度效应的影响;2. 阐 明悬索桥主要构件温度效应对总体温度效应的 贡献及相互之间的影响。 方法: 1. 建立现场环境和结构响应的结构健康监测系 统,并进行长期监测;2. 通过精细化有限元分析 方法实现桥梁温度荷载和温度效应的精准数值 计算。 结论: 1. 温度对大跨度悬索桥跨中位移的影响明显,其 一天的变化约是设计车荷载位移的10%;箱型主 梁横向温差是导致桥面横向倾斜的主要因素。 2. 箱梁温度应力显著大于车荷载引起的应力;部 分次要构件的温度应力成为主要荷载效应。3. 主 缆竖向倾角越大,温度应力越大;吊杆温度效应 主要受其长度和两端相对变形的影响。4. 桥塔温 度效应不仅受其自身温度的影响,也会受到来自 主缆温度响应的较大影响。5. 本文结论是基于一 天温度变化的影响,而温度效应在更大时间尺度 上的影响会更为严重。