Evaluation on root-deck fatigue of orthotropic steel bridge deck

Abstract

Orthotropic steel decks are widely used in cable-supported bridges. The fatigue cracks in trough-deck welded joints have been detected in some bridges in China. In this paper, the finite element method (FEM) is applied to evaluate fatigue durability of the root-deck fatigue in the trough-deck welded joints over the diaphragms. The reference stress is defined and the mesh size of a shell model is checked. Stress ranges under wheel loads are analyzed, and the pavement–deck interaction is discussed. The durability of the root-deck fatigue is evaluated. Results of this study show that the reference stress defined in the shell model is not sensitive to mesh size. Equivalent stress ranges of multi-axles are close to that of a single axle with multi-cycles. Traffic flow can be simplified as an axle fatigue load model with equivalent fatigue damage. Stress range regardless of the pavement–deck interaction is over estimated and the pavement–deck interaction should be considered in the stress range analysis, especially in thin decks. The predicted life of the root–deck fatigue considering the pavement–deck interaction seems to explain the fatigue cracks of bridges in China. The durability of the root–deck fatigue will be improved if steel fiber reinforced concrete (SFRC) pavement is applied.