Effects of Ambient Temperature and Magnitude of the Vibration on the Dynamics of Pre-Stressed Precast Isolated Pedestrian Bridges

Abstract

The dynamic properties of structures are known as inherent properties dependent on the mass and stiffness parameters. However, recent studies showed that the temperature and the magnitude of the vibration affect them. This study aims to reveal how the ambient temperature and human-induced vibrations alter the modal characteristics of pre-stressed precast isolated pedestrian bridges. For this aim, operational modal analyses have been applied to the Istanbul Medeniyet University pedestrian bridge. Three-bay pre-stressed precast and isolated bridge has been connecting the two campuses of the university for six years and its dynamic properties were investigated during its construction. In this study, the dominant frequencies of the bridge have been determined to see if they changed or not for its service life. Secondly, the dynamic response of the longest bay of the bridge has been evaluated under different temperatures and human-induced vibrations. Through a year, twelve acceleration measurements have been gathered in a temperature range of 5 – 33 °C and representing the different levels of human-induced vibrations, some jumping actions were applied and its response was recorded. While the performed analyses proved that, the dominant frequencies are dependent on the ambient temperature, no significant correlation was obtained between the amplitude of the vibration and the dominant frequencies of the bridge. High-amplitude vibrations have been used for the vibration serviceability check of the bridge, and it is seen that it satisfies the requirements set by different codes.