Monitoring a Timber Bridge in Norway

IRG/WP 04-40282

F G Evans

We have instrumented three different timber bridges in Norway for the Norwegian Public Roads Administration. The goal was to learn more about the properties of timber bridges. We have instrumented Evenstad Bridge, Daleråsen Bridge and the last year Flisa Bridge. All bridges are have creosoted glulam trusses and creosoted stress laminated deck. Evenstad and Flisa have an asphalt deck on top, while Daleråsen has wooden wear boards on top. This paper deals with Flisa Bridge only. In this bridge we monitoring the relative humidity (RH) and the temperature in the deck and the steel bar forces in the stress laminated deck since the construction in March/April 2003. The deck’s moisture content (MC) is calculated from the temperature and RH.. The results after 8 months shows that the steel bar forces are decreasing by time, but still within accepted tolerances. The calculated MC in the deck is in the start higher than in an untreated dummy but during time the deck have almost the same MC as the dummy.

Keywords: Timber bridges, creosote, moisture content, tension force, stress laminated timber

Conference: 04-06-06/10 Ljubljana, Slovenia

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