Simulation of the Effect of Temperature Variation on Damage Detection in a Long-span Cable-stayed Bridge

Damage detection based on structural dynamic characteristics, such as natural frequencies and mode shapes, is an important area of research. Obtaining accurate structural dynamic characteristics is perhaps the most challenging aspect of this research. In particular, changes in environmental temperature, due to seasonal weather or radiation from sunshine, will lead to changes in the dynamic characteristics of structures. In this study, the effects of change in environmental temperature on the frequencies and mode shape curvatures of a cable-stayed bridge are analyzed considering seasonal temperature difference (a uniform temperature difference) and sunshine temperature difference (an asymmetric temperature difference). Changes in dynamic characteristics due to temperature variation are compared to changes in dynamic characteristics due to damage of girders and cables in a cable-stayed bridge. Guidelines are presented in this study to explain how frequencies and mode shape curvatures change due to average and asymmetric temperature variations in the cable-stayed bridge. An important conclusion is that changes in dynamic characteristics of the bridge due to damage in girders or cables may be smaller than changes in dynamic characteristics due to variations in temperature. Suggestions are given to prevent changes in dynamics of the bridge due to damage from being submerged in changes in dynamics due to temperature effects.