InTrans / Aug 14, 2018

Effect of preservative treatment on bar force in stress-laminated bridge decks

Stress-laminated timber bridge decks have gained increased
popularity in the United States since the late 1980s. Like all exposed wood, the laminations in these bridges must be treated with wood preservatives to prevent deterioration from decay and insect attack. Traditionally, stress-laminated bridges are constructed using wood treated with an oil-type preservative. Waterborne preservatives are not widely used because of concerns about dimensional stability of the wood laminations. This paper describes a 2-year study that examines the performance of nine stress-laminated timber test decks constructed of Southern Pine lumber. The decks were
treated with seven different preservatives to assess comparative bar force retention over time. In addition, three
different bar anchorage systems were evaluated on decks
treated with the same wood preservative. Preliminary
results indicate that there are subtle differences in shortterm
bar force performance between decks treated with
oil-type and waterborne preservatives. In addition, the
bar force retention magnitude was more varied in the
decks treated with waterborne preservatives than in the
decks treated with oil-type preservatives. However, little
difference was noted in the performance of the three
bar anchorage systems.