Investigation into fatigue performance of river-sea ships subjected to the combined effect of wave loads

Abstract

[Objectives] Fatigue damage is considered to be common in marine engineering. River-sea ship is subjected to complex wave loads,which consist of river and sea. Its structural requirements lower than the sea, higher than the river boat. Fatigue strength of this type's structure needs further investigation. [Methods] A container ship is taken as the research object in this paper. The fatigue strength of river-sea ship is based on spectral analysis, combined with the China's coastal long-term wave loads data. And the fatigue damage rules of different checking points under different conditions were obtained and the differences of fatigue damage on the distribution of short-term sea conditions were studied. [Results] Analysis of the results shows that the fatigue damage in the sea area is mainly caused by the wave contribution of 2.5-5 m of significant wave height and 6-8 s of zero-crossing period. [Conclusions] Considering the combined effect of the river-sea wave loads, the fatigue life of the structure of the target ship is significantly increased. So only consider the sea wave environment is too conservative. The results provide the basis for the structural fatigue design of river-sea ship in the future.

Keywords

• river-sea ship
• fatigue damage
• spectrum method
• inland-river wave