DESIGN OF TRUNNION-HUB GIRDER ASSEMBLIES FOR BASCULE BRIDGES
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Home | Grant 1: (98-01) | Grant 2: (01-03) | Grant 3: (04-05) | Pictures | Links
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DESIGN OF TRUNNION-HUB GIRDER ASSEMBLIES FOR BASCULE BRIDGES Committed to bringing numerical methods to undergraduates |
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Home | Grant 1: (98-01) | Grant 2: (01-03) | Grant 3: (04-05) | Pictures | Links |
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Two different procedures are currently utilized for the assembly of the trunnion-hub-girder. Assembly procedure #1 (AP1) involves cooling the trunnion and shrink fitting it into the hub, and subsequently cooling the trunnion-hub assembly to shrink fit it into the girder. In assembly procedure #2 (AP2), the hub is shrink fitted into the girder first, and followed by cooling the trunnion and shrink fitting it into the hub-girder assembly. Several problems can occur during the assembly, including development of cracks on the hub as well as improper assembly due to insufficient cooling of the parts. This part of the work presents results from experiments used to determine the thermal and structural response of the trunnion-hub-girder assembly during the two assembly procedures. Quarter scale and full scale trunnion-hub-girders were instrumented with cryogenic strain gages and thermocouples to determine stresses and temperatures at critical points. It was found that large tensile hoop stresses develop in the hub at the trunnion-hub interface in assembly procedure #1 when the trunnion-hub assembly is cooled for insertion into the girder. These occur at low temperatures, and result in low values of minimum critical crack length. Peak stresses develop during assembly procedure #2 occur when the hub is cooled for insertion into the girder. However, the relative magnitude of the minimum critical crack length was found to be less than half that occurring during assembly procedure #1. The conclusions of this part of the work are that for the given full scale geometry and interference values, AP2 is safer than AP1 in terms of lower hoop stresses, lower Von-Mises stresses and larger critical crack lengths.
PICTURES Assembly Procedure#1 (AP1) pictures of full scale testing Assembly Procedure#2 (AP2) pictures of full scale testing
VIDEOS Watch a six minute video of the assembly procedure#1 (AP1)
REPORTS Full Report (Finite Element & Full-Scale Testing - Acrobat Format ; Word Format)
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