Institute for Transportation

The major parameters which determine performance of
wood structures are modulus of rupture (MOR),
modulus of elasticity (MOE), and loads. These
parameters are a subject to considerable variation and
therefore, they are treated as random variables. The
objective of this study is to develop an efficient
procedure for evaluation of the structural reliability.
The work will focus on wooden plank decks for
highway bridges. In particular, the paper is focused on
distribution of truck load to plank decks. The current
AASHTO Specifications are unrealistic and too
conservative in most cases. A plank element is
modeled as a beam on elastic supports. Material
properties, in particular MOE and MOR, are based on
the actual test data. The major part of the load model
is axle load, and in particular wheel load. The
statistical analysis is based on the available weigh-inmotion
measurements data. It was observed that truck
parameters are strongly site-specific. For plank decks,
live load consideration is focused on axle weights and
wheel loads rather than whole vehicles. The reliability
model will be used to develop rational design criteria
for plank decks.