Continuous Dynamic Monitoring of Human-Induced Vibrations at the Luiz I Bridge

The Luiz I Bridge is a century-old double-deck truss metallic structure over the Douro River in Porto, which was built to serve as a road and pedestrian link between the cities of Porto and Vila Nova de Gaia. For many years, this bridge has been submitted to high lateral vibration levels induced by pedestrians during the festivities of the St. John holiday that occurs every year in June, which arise from a phenomenon of pedestrian–structure interaction known as Lock-in. More recently, this structure has also been used during the athletic races that occur along the banks of the Douro River, some of which cross the lower deck of the bridge inducing high levels of vertical vibration. In order to measure these phenomena, the structure was instrumented with continuous dynamic monitoring systems in the context of the dynamic tests performed by the Faculty of Engineering of the University of Porto in the past few years. Within this scope, the main objective of this paper is to characterize the lateral and vertical vibration levels of both decks of the bridge measured since 2014 and to evaluate these vibration levels in terms of human comfort, by turning to the most recent guidelines in this area. The results of this investigation corroborate the adverse comments expressed by many people that use this structure.