Dynamic characterization of prestressed rods in stressed timber systems

Analytical and experimental approaches are presented to monitor the tension levels in posttensioned high-strength steel rods of stressed-timber systems. The, dynamic response of these rods under an impact load is correlated with the rod tension. The dominant frequencies of the rod stressed to different tension levels are consistently distinguishable. An increase in frequency is consistently observed with increases in the rod tension levels. An analytical relation is developed to correlate the dominant frequencies to the tension level in the rod. The proposed technique can predict the tension levels with a 85-90% accuracy of the experimental results. The nondestructive approach proposed herein is intended for future use in structural inspection of stressed timber bridges.