Indirect assessment of concrete resistance from FE model updating and Young's modulus estimation of a multi-span PSC viaduct: Experimental tests and validation

The paper discusses the possibility of reliably estimating the concrete resistance based on Young's modulus assessed from FE model updating using ambient vibration data. The procedure is applied to the FE model updating of a multi-span prestressed concrete bridge in Corvara (Italy). The bridge consists of seven spans, each made of seven prestressed concrete girders and a concrete deck. The operational modal analysis of the seven spans leads to estimating Young's moduli of the deck and the girders. The FE model's sensitivity analysis shows the modal parameters’ dependence to the Young moduli of the deck and the girders, proving that the detected modes are differently affected by the two modelling parameters. In a second step, the authors estimate the concrete resistance using a well-acknowledged empirical correlation between the Young moduli from FE model updating and the concrete resistance. Finally, the concrete resistance and its uncertainty, obtained by propagating the modelling error from the objective function to the concrete resistance, is compared to the concrete resistance assessed from destructive tests on concrete samples extracted from the bridge. The paper confronts the values of concrete resistance estimated from a non-destructive and a destructive method. The indirect method based on the tuning of the FE model yields a good matching in terms of estimated parameters. However, the variance from concrete samples is higher than that obtained from the indirect method. The authors discuss the causes of this discrepancy and highlight the pros and cons of the presented indirect method for estimating the material properties from ambient vibration data.