Evaluating the Strengthening Effect of a Cracking Cross-beam for a Steel Truss Bridge

A three-dimensional finite element model of a steel truss bridge is established, and the stress distribution under dead loads is investigated. Then the most cracked cross-beam is modelled into solid elements, whose bearing capacity are investigated before and after being strengthened respectively, and the effectiveness of strengthening is estimated by static analysis. The joint with a crack whose size and location come from the site inspection is modelled, and the J integral, the stress intensity factor and the crack growth rate are estimated under specified load, lastly the fatigue performance are compared between the model before strengthening and that of after strengthening. The results show that the bearing capacity of the strengthened joint is greatly enhanced, the local stress concentration and deformation are significantly reduced, and the stress distribution become more reasonable, which prove that the fatigue performance is greatly improved, and the strengthening work achieved its design goal. (paper)