An Investigation of the Load Distribution on a Timber Deck-Steel Girder Bridge

About the report:

The load distribution on a 48.5-ft. span timber deck-steel girder bridge built to the Virginia Department of Highways and Transportation standard SS-4 requirements was investigated under two conditions. The first condition was concerned with the load distribution when the timber deck fasteners were tight and the second condition involved investigating the load distribution when the fasteners were loosened in several stages. The results of the study indicated that the live load stresses were of the same general order of magnitude and that the lateral load distribution was generally the same whether the deck plank fasteners were loose or tight. The load distribution factor currently used for the interior girders was found to be too high, whereas the procedure used for distribution of the load to the exterior girders was slightly low. It is recommended that consideration be given to using a load distribution factor of S for the evaluation of both the interior and exterior girders of timber deck-steel girder bridges similar to the one investigated. Compared to current procedures, this modification would result in a 20% reduction in the live load distribution to the interior girders and a 28% increase in the distribution to the exterior girders.

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