Effect of Temperature on Modal Variability of a Curved Concrete Bridge under Ambient Loads

This paper reports on the effect of temperature on the modal properties for a curved posttensioned bridge. The goal has been to explore how ambient vibrations based on routine traffic excitation can be used as part of a long-term bridge monitoring approach. This requires the establishment of a baseline that incorporates the sensitivity of the measured modal properties. The ambient vibration characteristics are based on both the health of the structure and the environmental and operational conditions which may mask normal changes due to structural changes. The primary environmental influence on the structural modal properties is temperature. A database developed over a 5 year period to explore bridge monitoring techniques has been used to evaluate how temperature variations influence the modal properties. The results show that the variability of measured modal parameters due to temperature should be well understood and quantified prior to the establishment of a baseline for use in damage assessment algorithms.