Fatigue analysis of suspenders on continuous suspension bridge with displacement-controlled device

Main cable displacement-controlled device (DCD) is the special component to ensure the safe operation of continuous suspension bridges and has been widely used in engineering recently. To study the safety of this new type of structure during service and its influence on the fatigue performance of suspenders, a fatigue analysis framework of the suspenders on continuous suspension bridge with DCD under traffic loads was proposed. A new vehicle-bridge interaction (VBI) analysis method that can take road roughness into account was proposed for dynamic calculations. The fatigue analysis of the suspender system was conducted on a typical three-span continuous suspension bridge with DCD and the influence of DCD on the fatigue performance was also studied. Results show that the proposed method can effectively carry out fatigue analysis. Both types of DCD are beneficial to improving the fatigue life of suspenders. According to the analysis results based on the linear elastic fracture mechanics method, the fatigue life of the suspender will be reduced by up to 83.8 % due to the absence of DCD. Rigid DCD is more effective in solving fatigue problems with a maximum increase in fatigue life of 4.99 times. It is necessary to install DCD on continuous suspension bridges. The choice of DCD type mainly depends on the topographic factors of the bridge site. Since the impact effect of the vehicle is much smaller than the gravity effect of the structure, road roughness is not the main factor affecting the fatigue life of suspenders.