Experimental investigation on vibration characteristics of sympodial tree

Sympodial trees are prevalent in tropical and subtropical urban areas while suffering the threat of wind storms every year, which leads to unpredictable economic losses and secondary hazards. However, the research on the dynamics of sympodial tree, which exhibits extremely complex structures, is limited. Therefore, this study conducts wind tunnel tests to systematically investigate vibration characteristics for trees with different crown configurations. Results show that as the scaled Cauchy number increases, the base overturning moment coefficient ($C_M$) gradually reduces, yet its reduction rate decreases. Subsequently, a higher spectral peak and narrower bandwidth of $C_M$ is observed with the extent of pruning severity. Finally, an energy coefficient ($C_E$) is developed to depict the wind energy absorption ability of trees. It is revealed that $C_E$ displays a declining trend with an increase in $\mathrm{LA}{I}_1$ (leave area / ground area) and $\mathrm{LA}{I}_2$ (leaf area / frontal area). Furthermore, it is found that trees characterized by robust and squat trunks along with dense foliage possess an enhanced capacity for wind energy dissipation.