Development of decay hazard maps based on decay prediction models

IRG/WP 16-20588

J Niklewski, E Frühwald Hansson, C Brischke, D Kavurmaci

Durability plays a very central role in timber engineering, especially when working with wood in use class 3 and above where the risk of decay is high. As one of the primary decay influencing factors, the external condition, i.e. the local climate, is often graded by some type of climate index value. Predominately, climate indices are based on a direct relationship between weather data and decay. The aim of this paper was to develop a new type of climate index, including decay hazard maps, which explicitly considers the material climate. Firstly, the moisture content over time of a horizontal reference specimen was calculated using three different exposure models with weather data (rain, temperature, relative humidity) as input. Secondly, the output from the exposure models was post-processed using two different decay prediction models. Four different exposure model/decay-prediction model combinations were tested in total and repeated for many different locations in Northern Europe. Finally, the relative decay hazard between the different locations was calculated and interpolated, resulting in four preliminary contour plots visualizing the decay hazard in Northern Europe. The maps should be considered preliminary as they have not yet been verified against real decay data. The primary difference between the maps is the range of the relative decay hazard, i.e. the difference between the mildest and the most adverse conditions. The two extremes range between 0.6-2.6 and 0.8-1.8 respectively, which can be compared to the Scheffer index which ranges between 0.8-2.0. The next step, however not included in this article, is to compare the maps against real data.


Keywords: climate index, decay hazard, decay map, dose-response model, wood durability

Conference: 16-05-15/19 Lisbon, Portugal


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