Moisture conditions of rain-exposed glue laminated timber members: the effect of different detailing: the effect of different detailing

In performance-based durability design, relating the in-use conditions of wooden members to their moisture content is an important step. In the present study, the effects of detail design on the wood moisture content of glulam members are investigated experimentally. The moisture content of glulam members, designed with various connection details and structural protection, was monitored at 18 different measuring points (n = 3) by use of resistance-type moisture sensors for a period of a year. The effects of detail design are studied by comparing the moisture content of various details to that of a freely exposed beam. As expected, the design of the details was clearly reflected by their moisture content. Efforts to protect the wood were favourable in most cases, although only complete shelter kept the moisture content consistently below the level critical for the occurrence of decay. In order to relate the effects of moisture traps to the climate, a three-parameter empirical model was constructed and fitted to the experimental results. The model was able to capture the main features of the measurements and was used in order to characterize the performance of details in terms of their response to weather.