Reinforcing the Structural Stability of Old Nationally Important Trees with FRP Wraps

Abstract

This study evaluated the structural effects of applying fiber-reinforced polymer (FRP) wraps around their trunks to support old trees of national importance. High wind loads such as windstorms or hurricanes represent a major threat to tall trees, and researchers have assessed the structural behaviors of trees under wind loads using both analytical and experimental approaches. As yet, however, there is no widely accepted method to safely reinforce the structural stability of nationally and historically important tall trees subject to severe wind loads. Traditional reinforcing methodologies can actually damage supported areas as the supports are relatively stiff compared to the main trunk, introducing stressful interactions. FRP materials have high tensile strength, durability, and flexibility; hence, wrapping them around the surface of the tree trunk could enhance the overall stability of a tall tree subjected to high winds without sacrificing the tree's visual aesthetics or damaging the bark. This study applied nonlinear finite element (FE) analyses to evaluate the complex structural behaviors of the wood and FRP wraps, both of which are anisotropic materials. The results revealed that FRP wraps offer a highly effective way to enhance the structural stability of tall trees with minimal cost.