Institute for Transportation

The introduction of stress laminated lumber decks
has helped in the elimination of the problems
associated with conventional lumber decks.
However, there are thousands of conventional
lumber decks that will continue to require
maintenance. In some other instances, some of
these conventional wood bridges may be kept as
historical landmarks. One problem that needs
attention on these conventional lumber decks is
the one caused by dimensional instability of
lumber, when used in a varying environmental
condition. Proper material selection and proper
board placement may help in minimizing the
effect of these dimensional instabilities. However,
when we have wetting from one side only, there is
a cupping tendency regardless of material
selection and placement. In this paper results of a
study aimed at the determination of forces
developed during the cupping of lumber subjected
to uni-directional wetting are presented. The
forces developed during cupping depends on the
depth and width of the lumber.