This paper is a study of avoiding failures during the assembly of a trunnion-hub-girder (THG) for bascule bridges. The currently used assembly procedure, AP#1, cools the trunnion for a shrink fit into the hub, followed by cooling of the trunnion-hub assembly to shrink fit it into the girder. During assembly, using AP#1, development of cracks on the hub was observed in one THG assembly. Yet, during another assembly, the trunnion got stuck in the hub before it could be fully inserted. A complete analytical, numerical, and experimental study was conducted to understand these failures, and the results were used to develop specifications and recommendations for assembly. The causes of failures include development of high stresses at low temperatures during assembly, while noting that fracture toughness of THG material decreases with temperature. Recommended specifications included following an alternative assembly procedure that doubled allowable crack length, and lower cooling temperatures to avoid trunnions sticking in the hub.
Avoiding Failures During Assembly of a Trunnion-Hub-Girder for Bascule Bridges
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Besterfield, GH, Nichani, S, Kaw, AK, Eason, T, & Cherukara, T. "Avoiding Failures During Assembly of a Trunnion-Hub-Girder for Bascule Bridges." Proceedings of the ASME 2002 International Mechanical Engineering Congress and Exposition. Design Engineering. New Orleans, Louisiana, USA. November 17–22, 2002. pp. 825-833. ASME. https://doi.org/10.1115/IMECE2002-39605
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