FATIGUE LIFE ASSESSMENT OF A TRUSS GIRDER BRIDGE USING LINEAR FRACTURE MECHANICS APPROACH

In transportation system, bridges are continuously subjected to vehiclular loads that causes accumulation of stresses in different components. The weakest region are some times prone to the development of fatigue crack, that grows leading to collapse if proper maintenance and reparing are not carried out. In this paper, a method of estimation of fatigue life of a truss girder bridge has been outlined using linear fracture mechanics approach after synthesizing the vehicle induced stress history. Von-Mises stresses which accounts for all the principal stresses at a gusset plate of a critical joint was utilized to obtain stress-cycle histogram. Number of cycles required to grow an initially detected crack of very small dimension to a threshold value has been obtained to predict the fatigue failure. The effect of the length of the bridge, vehicle speed and compound traffic growth on remaining life of the bridge has been studied
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