PSI - Issue 84

Marco Pirrò et al. / Procedia Structural Integrity 84 (2026) 552–559

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(a)

(b)

Fig. 4. (a) Eccentric and (b) central position of the trucks during the load tests performed on the Dolo overpass.

For each series of tests, the trucks progressively advanced about 5 m every 5 minutes, from one abutment to the opposite one (covering 11 steps for each series, for a total of 33 steps) and the inclinations were recorded during all series. A typical time-history is illustrated in Fig. 5 where the different load steps are clearly distinguished. During each load step, LVDT sensors were used for measuring the deflection at 3 points (center and opposite sides of the cross-section) of each mid-span. These independent measurements permit to evaluate the capability of the developed procedures of approximating the deflection shapes by using only inclinations.

Fig. 5. Typical time-history of inclination during the static load tests of July 10 th , 2022.

Figure 6 shows an example of deflection curves calculated for the same stage, corresponding to the case of two eccentric trucks located in the central span (Fig. 4a). The experimental displacement values measured by the LVDTs for each stage are represented by crosses on the graphs. Figure 6a shows the deflection curve calculated by allowing vertical deflections at the intermediate piers and using the first procedure, which does not involve the information associated with transverse rotations. The use of the second procedure − using the displacement components evaluated through the transverse rotations − is exemplified in Fig. 6b and Fig. 6c. It should be noticed that: (a) Fig. 6b differs from Fig. 6c because the vertical deflection at central piers is set free (Fig. 6b) or equal to zero (Fig. 6c), respectively; (b) the latter approach (Fig. 6c) qualitatively leads to a worse result when comparing the calculated and LVDT-measured displacements. It is worth mentioning that examining the difference between computed and LVDT-measured deflections for each load step reveals that better approximation is generally achieved by the procedure using only the longitudinal rotations and leaving unconstrained the vertical deflection at the intermediate piers (Fig. 2a). As a further example, Fig. 7 shows the estimated displacements when the two trucks are centrally positioned on the left span (Fig. 4b) and the comparison with the LVDT-measured deflections. 5. Structural monitoring In the days immediately following the load tests of July 10 th , 2022, the data collected by the inclinometers shown in Fig. 3 were examined. Specifically, threshold rotation values were defined for the cross-sections resting on abutments and piers to generate alerts whenever these values were exceeded during the operating conditions, due to