REPAIR OF A THROUGH TRUSS ON THE VERGE OF COLLAPSE

An eastbound train transporting a 100 ton wrecking crane was travelling over an 894 ft long bridge crossing the St. Maurice River when the boom of the crane broke loose and hit the side of one of the 132 ft truss spans. The boom of the crane then swung towards the caboose, striking it and derailing both the crane and the leading truck of the caboose, resulting in further damage to the truss. Extensive damage resulted to a considerable number of main truss members, including an end post that was sheared by 60% of its cross-section on one side of the truss and on the other side shearing and twisting of up to 80% of the end post, diagonal, vertical, hanger and a large number of secondary members. This paper describes the design, analysis and unusual methodology used in replacing the damaged truss members in record time without the use of any type of shoring.