Dynamic testing and modeling of span interaction in high-speed railway girder bridges

This paper presents the results of an extensive experimental campaign conducted on high-speed railway girder bridges along the Rome-to-Florence railway line. The campaign includes material characterization and in-situ dynamic tests, incorporating vibration signals from both ambient-induced activities and train passages. The study focuses on the modeling and simulation procedures necessary for analyzing existing railway girder bridges, considering the dynamic interaction between adjacent simple supported spans. The degree of coupling caused by railroad equipment can lead to interaction phenomena, such as vibrations corresponding to mode shapes encompassing multiple spans, observed along the bridge. A multilevel modeling strategy is proposed, starting with a single span to identify the most accurate and computationally efficient modeling approaches (frame-based, shell-based, or mixed). Subsequently, full-scale and reduced-order models of the entire structures are developed, considering the connections between rails, superstructure, and piers, to study the interaction between adjacent spans. Three case studies are presented to demonstrate the general validity of the proposed approaches, comparing the numerical results with experimental outcomes obtained from the in-situ tests.