Have you seen "Timber Bridges - Design, Construction, Inspection, and
Maintenance" by the USDA? I have used it for a few timber bridges I have
designed and load rated. It is free (was a few years ago anyway) and is
pretty exhaustive on timber bridges.
They have what looks like a pretty good discussion on this topic, specific
to nail laminated longitudinal decking. They refer to AASHTO 3.25.2. Then
they use Dw (in inches) = truck tire width perpendicular to traffic (sqrt of
0.025P) + 2*t (deck thickness).
They also provide a table of t v. HS load to get the section properties
From: David Handy [mailto:dhandy(--nospam--at)trg.ca]
Sent: Thursday, March 16, 2000 8:28 AM
Subject: OHBDC-nail laminated wood deck
Does anyone know the width used for the design of nail laminated wood deck
when spreading out the load of a wheel. If not in OHBDC then what about
AASHTO? Clause 3-126.96.36.199 in OHBDC refers to stress-laminated wood decking.
However, I am dealing with nail laminated wood decking? I do not think this
is the same thing? Width noted there as Dt=0.3+0.4S (in metres) In the 1983
code width was shown as 0.4m (16"). Why the change in this value? and
should the 16" value be used?
David Handy, P.Eng