Withdrawal Resistance of J-Lags from Three Hardwood Species    (View PDF)

Brian Kane

Abstract: Cables are commonly installed to reduce the risk of failure of branches or co-dominants, but there are few empirical data to describe their performance. In contrast, the withdrawal resistance of lag screws in timber connections has been studied more carefully and is related to the shank diameter and threaded length of the lag, as well as the specific gravity of the wood. J-lags of three diameters were installed in three species and withdrawal resistance was measured immediately and up to four years after installation. Since only three fully installed J-lags were withdrawn, J-lags were also partially installed in two species. Growth of trees around the “J” of J-lags increased their withdrawal resistance, and the withdrawal resistance of partially installed lags generally followed prediction equations developed for lag screws used in timber connections. Withdrawal resistance of J-lags did not exceed cable tensions previously measured and simulated.

Keywords: Cabling; Decay; J-lag; Tree Support Systems; Withdrawal Resistance

https://doi.org/10.48044/jauf.2011.018