Abstract
The long-term loading strength of end-notched beams made of glulam and LVL was tested. The beams were of various sizes, with and without a moisture sealing at the notch. Tests were conducted in open shelter climates, and at constant and cyclic relative humidity. The short-term strength was tested after conditioning in the various climates. Both the short-term and long-term strength of beams without moisture sealing was significantly affected by transient moisture conditions, e.g. the moisture variations due to change of the time of the year. The strength was only slightly affected by the magnitude of the humidity, if this was kept constant. Duration of load strength reduction factors were evaluated for 6 months of loading. Average reductions in ultimate failure strength ranged from 0.68 for small LVL beams without moisture sealing tested during spring and summer to 0.81 for large glulam beams with a moisture sealing at the notch.
Zusammenfassung
Die Zeitstandfestigkeit keilverzinkter Träger aus Glulam und LVL wurde geprüft. Die Balken waren unterschiedlich bemessen und mit oder ohne Endversiegelung versehen Die Prüfung erfolgte sowohl in natürlichem, geschützten Klima als auch bei konstanter Feuchte und im Wechselklima. Die Kurzzeitfestigkeit wurde jeweils nach dem Konditionieren geprüft. Alle Ergebnisse an nicht versiegelten Proben waren deutlich beeinflußt durch Feuchteübergänge, z.B. die Feuchtewechsel innerhalb eines Jahres. Die Festigkeit hing nur in geringem Maße vom Wassergehalt ab, wenn dieser konstant gehalten war. Reduktionsfaktoren (k mod) wurden für ömonatige Belastung ermittelt. Die durchschnittlichen Werte für die Bruchlast lagen im Bereich von 0,68 für kleine LVL-Träger ohne Feuchteversiegelung (geprüft im Frühjahr und Sommer) bis zu 0,81 für lange Brettschichtholz-Träger mit Feuchteversiegelung der Keilzinken.
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Gustafsson, P.J., Hoffmeyer, P. & Valentin, G. DOL behaviour of end-notched beams. Holz als Roh- und Werkstoff 56, 307–317 (1998). https://doi.org/10.1007/s001070050325
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DOI: https://doi.org/10.1007/s001070050325