Abstract
The cable-stay bridge is a complex hyperstatic structure with large span and slender proportions, making it highly sensitive to temperature, especially in terms of deformation. A cable-stayed bridge with a steel tower and steel box girder was taken as an example in this study to explore the temperature effects on the deflection of the main girder under different time scales. The temperature gradient characteristics of the girder and tower were observed; then, the daily and annual variations of girder deflection were investigated. Finally, the main influencing factors of deflection variations with temperature were verified by finite element simulation. The results show that the girder/pylon temperature gradient under current Chinese code is not applicable to cable-stayed bridges, and the measured values are usually underestimated. In terms of diurnal variations, the deflection is greatly affected by the temperature difference between the cable and beam and the temperature gradient of the girder. The annual variation law of deflection data and temperature at 1 : 00am shows obvious linear characteristics. The daily deflection at 1 : 00am., after removing the temperature effect, can thus be used as an index to evaluate the long-term degradation of bridges. This is a workable approach for efficient and rapid mining of large sets of monitoring data.
Highlights
Cable-stayed bridges are components of many transportation systems across the globe. ey are popular as they are aesthetically pleasing and have strong mechanical and economic performance
Temperature Distribution of Steel Box Girder. e vertical temperature gradient is an important temperature effect in the steel box girder, as it significantly affects the stress of the structure. e temperature gradient distribution assessed in this study is discussed
Our conclusions based on time multiscale effect analysis of deflection in a steel cable-stayed bridge with temperature variations can be summarized as follows: (1) e girder temperature gradient and the tower temperature gradient in current Chinese codes cannot be reasonably applied to steel box girders in steel cable-stayed bridges
Summary
Cable-stayed bridges are components of many transportation systems across the globe. ey are popular as they are aesthetically pleasing and have strong mechanical and economic performance. Five-day monitoring data of the Zhanjiang Bay Bridge in the summer of 2008 showed that the mid-span deflection of the main girder increased during the high-temperature period [13]. Monitoring data of the Donghai Bridge from March to September 2007 showed that mid-span deflection decreased with an increase in the average temperature over the main girder; a time lag Mathematical Problems in Engineering emerged between the deformation and the temperature as well [7]. Zhou et al [17] investigated the effects of seasonal as well as diurnal temperature variations on thermally induced changes in the mid-span vertical displacement of steel bridges; they assessed the effects of the distance between the two tower tops and cable tensions based on monitoring data for steel box girder and twintower cable-stayed bridges. The appropriate index was established to efficiently and accurately reflect the long-term structural degradation. e conclusions of this work may deepen our understanding of the temperature effects of steel cable-stayed bridges and provide an approach for efficient and rapid mining of large quantities of monitoring data
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