Performance of Bridge Timber Ties Under Static and Fatigue Loading

This study is in response to the dramatic increase in railway car axle loads that has occurred over the last 50 years. The paper presents the results of an experimental program undertaken to evaluate the structural performance of treated timber bridge ties under different railway car load levels. A portion of a prototype bridge deck, consisting of eight prototype timber bridge ties, was tested under various loading and support configurations to determine the axle load distribution. The serviceability of the treated bridge timber ties was evaluated based on the fatigue strength of eight prototype timber ties under different load levels. A theoretical model, based on energy principles, was developed to predict the axle load distribution to the ties for different span configurations. The model compares well with the measured test results and it complies with the American Railway Engineering Association requirements.