Abstract: Steel structure crane beams have been widely used in industrial buildings. Due to the existence of stress concentration, parts of crane beams with geometric discontinuity are in service under multiaxial stress. In this paper, finite element method is used to analyze the stress and strain state of crane beam, determine the position of dangerous point, and extract its stress and strain component. Taking the plane with the highest energy density as the critical plane, a method to determine the critical plane based on energy criterion is proposed. Given that the crane beam works under asymmetric load, with the help of Goodman equation of mean stress correction, the fatigue life of crane beam is calculated by combining the approximate S-N curve of Q355D steel. The proposed method considers the effect of the multiaxial stress near the region of stress concentration on the fatigue damage and provides a new method for fatigue life evaluation of steel members with geometric discontinuous under complicated stress.

Key words: crane beam, multiaxial stress, fatigue life prediction, approximate S-N curve, the finite element method