Structural health assessment of concrete half-joint bridges: from load testing to FEM simulation accounting for material uncertainties

The highway network includes many bridges constructed in series with identical structural scheme and subjected to comparable environmental exposure. This suggests developing strategies for assessing the entire family of such bridges as a whole, rather than a single manufact. A configuration used extensively in the last century, especially for road overpasses, is the Gerber half-joint, which has some critical peculiarities as demonstrated by recent collapses. This paper deals with a series of 18 road overpasses with Gerber half-joints in Sicily, Italy, having same age (early 1970s) and structural scheme. An experimental-numerical procedure is elaborated for assessing the structural health of these overpasses under service loads. The procedure encompasses an experimental investigation for the material characterization followed by dynamic and static field tests. Field tests are interpreted to calibrate a finite element model of the bridge deck, by outlining specific guidelines for developing a field-validated digital twin of concrete half-joint bridges. Inherent material uncertainties are incorporated in the numerical simulation by statistically processing strength parameters experimentally identified. The proposed method can be used for rationally exploiting diagnostic field tests combined with numerical simulation for an overall assessment of bridges having similar characteristics at a large scale.