Road overpasses with Gerber half-joints: Field tests and numerical models

This contribution presents a combined experimental-numerical investigation on road overpasses with Gerber half-joints. The analysis is focused on a series of existing overpasses of the A20 highway, Sicily, Italy, built more than 50 years ago and characterized by a Niagaratype Gerber deck with prestressed concrete girders and transverse diaphragms. The structural health of the overpass deck is assessed by diagnostic field tests combined with numerical simulation. First, dynamic free-vibration tests under the transit of trucks are conducted in situ to determine the bridge deck modal characteristics (frequencies and modal shapes) through a recently developed identification strategy. The experimental results are used to calibrate a finite element model, which is finally used to simulate the deflection response of the deck under static load tests. The results of this study are useful to develop field-validated digital twins of real bridge structures and for performing parametric analysis when designing repair interventions, where necessary.