InTrans / Aug 14, 2018

Bending Tests of Bridge Deck Planks

This paper presents results of timber plank tests, for planks used in highway bridge decks. Tests were carried out to determine the flat-wise use factor, which is represented by the ratio of modulus of rupture (MOR) for flat-wise loading to MOR for edge-wise loading. Four sizes were tested. The tests confirmed that MOR for flat-wise loading is considerably larger than for edge-wise loading for the larger planks tested and that flat-wise use factor increases for larger plank width. The flat-wise use factor in the current bridge design code is overly conservative for typical plank sizes. New flat-wise use factors are recommended for the design of wood plank decks for highway bridges. The recommended values vary from 1.10 to 1.6.