基于长期实测数据的大跨悬索桥扁平钢箱梁温差特性研究

温度应力是影响大跨桥梁结构全寿命性能的主要因素之一,合理的温度场分布模型是准确计算结构温度应力的基础。基于润扬大桥悬索桥结构健康监测系统的监测数据,详细分析润扬大桥悬索桥扁平钢箱梁为期一年的实测温度结果,得出横截面不同位置温度随时间的变化规律,提出扁平钢箱梁同一横截面上不同测点之间温差的概率分布模型,确定不同横截面具有一定重现期的温差标准值,总结用于温度应力计算的横截面温差模式。分析结果表明:①扁平钢箱梁的温度场具有明显的季节特征;②横截面各个测点之间的正温差和负温差均可以通过Weibull分布函数和正态分布函数的加权和来描述其概率分布;③同一横截面上不同测点之间有不同的温差标准值,但不同截面对应位置的温差标准值十分接近;④扁平钢箱梁顶板存在三种不同的横向温差模式。研究结果可为大跨悬索桥全寿命评估提供参考。

Thermal difference characteristic analysis of a flat steel box girder in long-span suspension bridge based on long-term field measurement data

Thermal stress is one of main factors that affect the life-cycle performance of long-span bridges.Reasonable thermal field distribution model is the basis for accurate calculation of structural thermal stress.Based on a set of one-year field measurement data obtained by structural health monitoring system of the Runyang Suspension Bridge(RSB),the thermal characteristics on the flat steel box girder of RSB are analyzed.Variation of temperature on the flat steel box girder with time is deduced,the thermal differences,i.e.the temperature differences among measurement points located in the same cross section are computed,and probability distribution models of the thermal differences are proposed,the standard values of thermal differences in representative cross sections,in a return period of 50 years,are calculated,and the thermal difference models for thermal stress calculation are summarized.The results show that the variation of temperature in the flat steel box girder has obvious seasonal characteristics,with both positive and negative thermal differences,both of which can be described by a weighted sum of Weibull distribution and normal distribution.The standard values of thermal difference in the same cross section are different,but the homogenous standard values of thermal difference in different cross sections are almost equal.Three different thermal difference distribution models exist for the top plate of the flat steel box girder.