Horizontal and vertical bridge dynamic response to vehicle loading

Abstract

The paper deals with the friendly and positive side of the vehicle–bridge interaction, presenting the main results derived from the experimental dynamic measurements carried out in several bridges with very different transverse and longitudinal cross–sections (continuous concrete slabs, box–girders, cable–stayed, etc). The bridges were excited dynamically by different heavy vehicles, with different number of axles and vehicle load configurations, crossing the bridge deck at different velocities. Most of the tests were performed to obtain a principal vertical (flexural deflection) vibration of the bridge. In this way, the dynamic bridge–vehicle interaction is presented thorough the value of the dynamic amplification factor obtained at different locations of the bridge and truck speeds. Some of the results derived in the tests performed in the Alamillo cable–stayed bridge built in Sevilla for the Universal Exhibition EXPO–92, with a single span of 200 m, are also included, showing the vehicle–bridge interaction not only in the deck but also in the pylon, via the stays, where both transversal and longitudinal vibrations were recorded during the running of the trucks over the deck. The final example of the paper deals with the results coming from the horizontal dynamic response of the Odiel bridge in Huelva, completed in 1993. The bridge has a total length of 2022 m (the longest in Spain) with typical span–length of 40 m. The total length of the bridge is divided in 6 segments. All the 6 segments of the bridge were dynamically excited in the horizontal direction using vehicle–braking over the bridge, resulting in important conclusions concerning bridge–vehicle interaction in horizontal plane and dynamic response of sub–structure elements (piers and foundations) thorough bearing devices, due to vehicle excitation.