Dynamic Monitoring of a Short-Span Railway Bridge During Construction

Despite numerous studies with respect to stiffness contributions of non-structural components of railway bridges, there is still a considerable amount of uncertainty in this respect. This contribution describes an experimental study of modal parameters of a short-span railway bridge at different construction stages. For this purpose, the modal parameters of a filler-beam bridge were identified from continuous monitoring over all phases of construction, from placement of the prefabricated bridge deck until the first train passage. Throughout the construction process, vibration data were continuously collected using accelerometers installed at relevant locations along the bridge. Both ambient and construction-induced responses were evaluated through Stochastic Subspace Identification Covariance (SSI-cov) method to determine the bridge’s natural frequencies, mode shapes, and damping ratios. The results show how non-structural components that were added to the considered system in stages influenced the dynamic characteristics of the structure and contributed to changes in its overall stiffness and vibrational behavior.