PSI - Issue 64

Amedeo Caprino et al. / Procedia Structural Integrity 64 (2024) 2149–2156 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. "Ponte Nuovo del Popolo" in Verona

2.2. Description of damage state The load-bearing structure is very degraded at the main longitudinal beams, especially the in the (2 for each side). The intrados of these beams has 6 longitudinal reinforcing bars of 30 mm diameter almost almost totally exposed to weather due to spalling of the concrete cover. In addition, throughout the length of the beams, at the upper rainwater drains, the reinforcement bars are totally corroded and uncovered. In several positions such degradation was also detected in the transverse beams. Indeed, there is a percolation of water from the deck, that damages the beams and stringers concrete, which is heavily deteriorated, moldy and carbonated. The rebars, at areas where water percolation occurs, are completely uncovered and visible, as the cover plate has been eroded by water and the pollutants it carries. There is also severe corrosion of the reinforcement bars, resulting in a net reduction of the resistant steel section (Fig. 2).

Fig. 2. Damage state of some of the main beams.

2.3. On-site testing Four reinforcing bars, in positions that would not aggravate the structural situation, were extracted to specify material attributes such as steel and concrete, as well as ten circular concrete cores with a diameter of 100 mm. Tensile testing on steel samples were conducted in the laboratory, while cylindrical compression experiments on concrete cores were performed to determine the secant modulus of elasticity. In addition, on-site rebound hammer tests on concrete in beams and stringers were carried out. Finally, dynamic identification test was conducted to define the modal parameters of the structure (frequencies, modal shapes, damping). The results of the dynamic identification were subsequently used for the design of the monitoring system layout.