Fatigue Cracks in the 60-year-old steel Structure of the Bridge

Abstract

The paper shows the fatigue cracks that appeared in the steel girders under the orthotropic plate inside the bridge structure. During decades of exploitation, fatigue cracks developed both in the base material and in the welded joints of the steel girders. Frequent stress cycles due to increased traffic and occasional overloads caused the cracks to propagate over time. Fatigue cracks propagation shortens the life of the steel structure and drastically affects the structural integrity of the bridge. As an effective tool in the detection and evaluation of fatigue cracks in steel bridges, NDT methods occupy a significant place. Non-destructive field methods used for the purpose of fatigue crack detection were magnetic particle testing and penetrant testing. The non-destructive metallographic method of the replica was used to assess the type of crack, and the examination of the taken replicas was carried out in the laboratory using light optical microscopy. Timely detection and repair of fatigue cracks in steel bridge components are key maintenance activities that can prevent potential failure. The paper lists some of the methods that were used for stop the propagation of fatigue cracks. The aim of the paper is to show some of the "in-situ" methods of identification and repair of fatigue cracks in the steel structure of the bridge after 60 years in service.