Study on fatigue performance of lightweight composite bridge deck with closed ribs
Peng Bo1,3 Shao Xudong1,2
1. Key Laboratory for Wind and Bridge Engineering of Hunan Province, Hunan University, Changsha 410082, China
2. School of Civil Engineering, Hunan University, Changsha 410082, China
3. Hunan Road & Bridge Construction Group Co., Ltd., Changsha 410007, China
Abstract：Taking the Second Dongting Lake Bridge (a suspension bridge with a lightweight composite bridge deck) as an example, hot spot stress approach is used to study the fatigue-cracking details of welds and calculate the stress ranges. Comparative analyses show that the stress ranges of fatigue details related to diaphragms are still very high. In order to optimize the mechanical behavior of fatigue details, parameter analyses are performed to investigate the typical cutout types of closed ribs of diaphragms which are adopted in domestic and foreign codes and the thicknesses of various diaphragms based on finite element analysis. The results reveal that, compared with traditional steel bridge deck, the stress ranges of fatigue details of lightweight composite bridge deck with closed ribs can be reduced by 21.7%~85.7%| the type of cutout adopted in railway bridge recommended by Eourcode3 is better than others| changing the thickness of diaphragm can significantly decrease the stress level of fatigue details around diaphragms. Additionally, the full-scale model fatigue test indicates that, the fatigue performance of circular-arc transition on diaphragms of the Second Dongting Lake Bridge can meet the design requirements| the study on 3 different bonding modes between the layer of STC and steel top plate implies that, strengthening the interface bond can improve the mechanical behavior of lightweight composite structure.
