Full-Scale Testing and System Identification of a Steel-Trussed Bridge

Abstract

This chapter describes the structural assessment, recently carried out on a steel trussed bridge dating back to the early 50s. The investigation included full-scale dynamic and static tests; in the dynamic tests, two different excitations techniques were considered—traffic-induced ambient vibrations and free vibrations. The main objectives of the research were to identify the principal modes of vibration of the bridge from ambient and free vibration measurements, verify the accuracy of modal parameters estimated from ambient vibration survey using the free vibration results, use the identified modal behavior in order to calibrate and update a 3D finite element model with respect to the main uncertainties involving the boundary conditions, and verify the results of the updated model by comparing the displacements and the stress levels measured during the static tests with the predicted ones. In calibrating the finite element model, the importance of making appropriate assumptions about the constraints and the boundary conditions are also explained in the chapter.