A COMPUTER SIMULATION OF AN ALTERNATIVE DESIGN TO TREE CROWN SUPPORT SYSTEMS    (View PDF)

Craig M. Greco, Andy Lee, Donald Ham, E. Thomas Smiley, and E. Harry Law

Abstract: Trees with multiple leaders that are susceptible to breaking pose a serious threat to nearby people and structures, and compromise overall tree health and aesthetics. The traditional remedy has been to install flexible steel cables in the crown of the tree in an attempt to limit the displacement of the leaders. This project was conducted to evaluate an alternative three-leader support cable system using computer simulation. The system is centered on a pulley that redirects loads along convergent cables, allowing for more displacement of the cabled leaders while minimizing the amount of materials and time required for installation. Comparisons between the traditional system and the alternative design were simulated using two-dimensional computer modeling to quantify the forces on the cables. The test winds were standardized at 43.45 km (27 mi) per hour for duration of 2 seconds. An interval of 18 seconds was allowed for the system to return to equilibrium for a total trial time of 20 seconds. Each system was standardized for cable diameter, damped springs, and distance between leaders with only the total length of cable varying according to the requirements of each system. Results demonstrated a significant decrease in both overall and shock forces to support cables when utilizing the alternative design. The decrease in force (based on cable configuration and wind direction) ranged from a 3.4:1 to 22.4:1 for the alternative and traditions systems, respectively.

Keywords: Cabling; canopy support systems; loads; displacement; computer modeling.

https://doi.org/10.48044/jauf.2004.044