PSI - Issue 64

Vera Rillo et al. / Procedia Structural Integrity 64 (2024) 700–707 Rillo et al./ Structural Integrity Procedia 00 (2019) 000 – 000

702

3

j   2 ij

 = N i j

i ADPR

(3)

=

The above-mentioned techniques are based on a modal matching criterion, known as MAC- Modal Assurance Criterion (Allemang and Brown,1982) The MAC value is a robust and effective parameter to apply to preliminary modal shapes since errors in modes estimated from FE models or preliminary field tests do not significantly affect it (Minwoo, 2024). The Modal Assurance Criterion is a criterion used to compare numerical data with measured data as in equation (4): = |{ } ∙{ }| 2 ({ } ∙{ })∙({ } ∙{ }) (4) where: The correlation between modal values is studied by considering the values on the main diagonal (trace) and the values outside of it (off-diag). The MAC value ranges from 0 to 1, and the comparison can be considered satisfactory with a value higher than 0.8. In the following sections, the three selected methods are applied with reference to a case study. 3. Case study 3.1. Brief Description The selected case study pertains to a newly built vehicular and pedestrian bridge located in Benevento, Italy. This bridge comprises three spans, the end spans are 24.85m long each while the central span is 38.00m long, thus the deck has a total length of 87.70m. The roadway width measures 9.50m. It consists of two piers positioned within the riverbed and two abutments extending beyond the riverbanks, the bridge's general view is illustrated in Fig. 1. • is the numerical eigenvector corresponding to the i-th mode; • is the measured eigenvector corresponding to the i-th mode.

Fig. 1. General view of the bridge.

The road deck is built with a composite steel-reinforced concrete structure. The cross-section involves the adoption of four main beams with HSA1400/700 electrowelded profiles spaced at 2.90m, with transverse crossbeams using HSA1400/400 electrowelded profiles at both the ends and along the axis resting on abutments and piers. Along the three spans, on the other hand, the respective transverse beams are realized by interposing IPE 500 profiles.