Prediction of timber twisting based on measured spiral grain of spruce trunks and logs

0575777 - ÚTAM 2024 RIV US eng C - Konferenční příspěvek (zahraniční konf.)
Kloiber, Michal - Kunecký, Jiří - Kotmel, M.
Prediction of timber twisting based on measured spiral grain of spruce trunks and logs.
WCTE 2023. Proceedings from the 13th World conference on timber engineering. Red Hook (NY): Curran Associates, 2023 - (Nyrud, A.; Malo, K.; Nore, K.), s. 787-793. ISBN 9781713873273.
[World conference on timber engineering. WCTE /13./. Oslo (NO), 19.06.2023-22.06.2023]
Grant CEP: GA ČR(CZ) GA21-29389S
Institucionální podpora: RVO:68378297
Klíčová slova: timber * spiral grain * twist * structural repair
Obor OECD: Construction engineering, Municipal and structural engineering
https://doi.org/10.52202/069179-0108

This work focuses on the prediction of timber (beam) twisting based on the measurement of spiral grain under the bark of spruce trees (using Fakopp) and the subsequent measurement of spiral grain of logs during manipulation using a slope of grain detector. When selecting wood, it is necesary to take account of the effect of spiral grain on sawings - based on international practice - a spiral grain up to 5% deviation per 1 m of log length is not considered a defect. However, it is important whether the spiral is left-handed or right-handed, as measured on the log perimeter. Left-handed spiral increases after log processing while right-handed spiral decreaces. The perimeter of an element from a left-handed log that was within the acceptable 5% angle deviation per 1 m of length manifests a considerably higher deviation when machined, when markedly affects the timber twist during drying. By contrast, beams from right-handed logs with up to 5% deviation per 1 m of length have perimeter without spiral grain, and they are not defected by twist during drying. This phenomenon has been confirmed by the study conducted. Further, a good prediction of spiral grain in trees has been achieved using non-invasive equipment, Fakopp ArborSonic Microsecond Timer.
Trvalý link: https://hdl.handle.net/11104/0345505