An Experimental Analysis of the Real Dynamic Behavior and the Reliability Verification of an Existing Footbridge

The investigated existing footbridge, on which the dynamic experimental analysis was concentrated, was built across Vltava River in Prague in 1984. Since putting into operation, the footbridge was apparently sensitive to dynamic excitation by passing pedestrians. Above that in the course of its existence the considerable part of the footbridge deck was overflowed by two great floods that happened in August 2002 and in June 2013. After the second flood, a visible damage on the footbridge deck was detected by a visual inspection. The described dynamic experiment was divided into two basic parts. The experimental modal analysis was carried out first and then the dynamic load test was realized. It was focused to the deck vibrations induced by different pedestrians groups. It was found out the footbridge deck vertical accelerations exceed the pedestrian comfort limit in some normal situations. On the basis of comparison between modes of natural vibrations, which were evaluated by the experimental modal analysis and the equivalent ones from previous dynamic experiments, it was validated that the discovered deck damage caused the partial variation of fundamental dynamic footbridge behavior.