# Mechanical properties analysis of the interspersed replacement of timber sleepers with bamboo-based composite sleepers on open bridge deck

## TL;DR

This study examines replacing some wooden bridge sleepers with bamboo-based composites to improve mechanical performance and safety.

## Contribution

The paper introduces a novel approach to track structure upgrades using bamboo-based sleepers with interspersed replacement strategies.

## Key findings

- Interspersed replacement reduces sleeper compression and vertical displacement but increases bending moment and dynamic responses.
- Maximum tensile and compressive stresses in bamboo sleepers remain below allowable limits, ensuring structural safety.
- Track deformation and dynamic responses stay within acceptable ranges despite uneven stiffness from replacement.

## Abstract

Due to the discrete deterioration characteristics of timber sleepers on open bridge deck, continuous replacement is difficult. New bamboo-based composite sleepers (BCSs) offer excellent performance at a low price, making them an ideal alternative to timber sleepers. Therefore, this study focuses on the mechanical properties and safety of the interspersed replacement of timber Sleepers with BCSs. A static model of the open deck track and a vehicle-track coupling dynamic model were established to precisely analyze the influence of 1 in 2, 1 in 3, and 1 in 4 interspersed replacement, as well as full replacement with BCSs on the force and deformation of the track structure and the dynamic characteristics of the vehicle-track system. After the interspersed replacement of timber sleepers with BCSs, the sleeper compression, sleeper vertical displacement, and gauge reduction were decreased; however, the sleeper bending moment, vehicle acceleration, wheel-rail force, and bridge deck acceleration were slightly increased. At the longitudinal beam support, the BCSs showed a negative bending moment, with compression at the bottom and tension at the top. The maximum tensile and compressive stresses were 4.87 MPa and 7.97 MPa, respectively, which are both below the allowable stress of the material—meeting the strength requirements for BCSs. Although the interspersed replacement of timber sleepers with BCSs leads to uneven track stiffness, the track deformation, stress distribution and dynamic response remain within acceptable limits. This research provides new ideas for track structure upgrades and maintenance strategies.