Abstract
Strength of wood is normally measured in ramp load experiments. Experience shows that strength increases with increasing rate of testing. This feature is considered theoretically in this paper. It is shown that the influence of testing rate is a phenomenon, which depends on the quality of the considered wood. Low quality wood shows lesser influence of testing rate. This observation agrees with the well-known statement made by Borg Madsen that weak wood subjected to a constant load, has a longer lifetime than strong wood. In general, the influence of testing rate on strength increases with increasing moisture content. This phenomenon applies irrespective of the considered wood quality such that the above-mentioned order of magnitude observations between low and high quality wood are kept.
Zusammenfassung
Die Festigkeit von Holz wird in der Regel in Versuchen mit konstanter Belastungsgeschwindigkeit bestimmt. Aus Erfahrung ist bekannt, dass die Festigkeit mit zunehmender Belastungsgeschwindigkeit zunimmt. Dieses Phänomen wird hier theoretisch untersucht. Es wird gezeigt, dass der Einfluss der Belastungsgeschwindigkeit von der Qualität des Holzes abhängt. Bei Holz geringer Qualität ist der Einfluss geringer. Dies stimmt mit der bekannten Feststellung von Borg Madsen überein, dass bei konstanter Langzeitbeanspruchung Holz geringerer Festigkeit eine größere Belastungsdauer bis zum Bruch aufweist als Holz höherer Festigkeit. Im Allgemeinen nimmt der Einfluss der Belastungsgeschwindigkeit auf die Festigkeit mit höherer Holzfeuchte zu, wobei der Einfluss der Holzqualität unverändert erhalten bleibt.
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Nielsen, L.F. Strength of wood versus rate of testing . Holz Roh Werkst 65, 223–229 (2007). https://doi.org/10.1007/s00107-006-0159-z
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DOI: https://doi.org/10.1007/s00107-006-0159-z