Effects of Redecking from RC Deck to Orthotropic Steel Deck on Seismic Resistance of Elevated Girder Bridges

Due to the rapid deterioration of reinforced concrete decks (RCD) under the combined effects of deck overloads, weather and salts, the orthotropic steel decks (OSD) that are light weight and require less construction time are being used increasingly to replace old deteriorated decks. In this paper, a numerical investigation was carried out to study the effect of reduction in superstructure weight on the earthquake resistance of elevated girder bridges when an existing RCD was being replaced by an OSD. Firstly, an eigenvalue analysis was carried out to study the effect of superstructure weight on the global vibrational characteristics of the bridge and then, the evaluation of seismic performances of both the bridge models were carried out by performing a series of non-linear dynamic analysis with input earthquake data in the longitudinal and transverse directions separately and simultaneously. The behavior of the pier bases was examined by monitoring the displacement responses and plastic strains during earthquakes. It was found that the bridge model with OSD exhibits a shorter period of vibrations and a huge improvement in the seismic performance of the bridge was observed by replacing the existing RCD with the OSD. The analysis results could be useful in finding a solution for seismic retrofit of existing girder bridges.