# Nonlinear hysteretic behavior and anchorage performance of Betula platyphylla roots under cyclic loading

## TL;DR

This study investigates how repeated loading affects the root anchorage of Betula platyphylla trees and develops a model to capture their mechanical behavior under cyclic stress.

## Contribution

An enhanced Bouc-Wen model is introduced to accurately represent the nonlinear hysteretic behavior of tree roots under cyclic loading.

## Key findings

- Peak bearing capacity of roots decreases with increasing load amplitude.
- Energy dissipation in roots initially decreases sharply with cycles but stabilizes after 25 cycles.
- The enhanced Bouc-Wen model successfully replicates hysteresis loops and damage progression in root anchorage.

## Abstract

Cyclic loads caused by natural factors such as strong winds are common in plant growth environments. Prolonged exposure to such loads can compromise the anchorage performance of plants. This study examines how cyclic loading influences the root anchorage of Betula platyphylla, a prominent tree species in northern China.

A series of pull-out tests were performed on soil-embedded roots, including monotonic pull-out tests and 100 cycles of loading and unloading.

The research results show that under different cyclic load amplitudes, the peak bearing capacity is negatively correlated with the load amplitude. Energy dissipation in the root system increases with higher load amplitudes but decreases as the number of cycles increases. From the initial cycle to the 25th cycle, energy dissipation decreased substantially, with no further significant reduction observed between the 25th and 100th cycles. To more effectively capture the nonlinear hysteretic behavior of roots, an enhanced Bouc-Wen model was developed and successfully fitted to the force-displacement curves. The model accurately replicated the hysteresis loops and characterized the damage progression in root anchorage under cyclic loading.

These findings offer valuable insights into the mechanical stability of plant roots under repeated environmental stresses and provide a robust framework for modeling root anchorage performance in natural settings.