Compressive Behavior of Reinforced Concrete Pedestals with Corroded Steel Reinforcements

The behavior of concrete pedestals for the transmission of loads from bridge deck to substructure is investigated till failure. An experimental campaign with 24 prismatic pedestals tested in compression was carried out with different heights/width ratios and percentages of steel reinforcement at the bottom edge. Corrosion of the lower reinforcements was induced to simulate the behavior of pedestals of existing bridges, by placing specimens in a tank with sodium chloride producing a pitting attack. The effective potential measurements, the tensile tests on the reinforcing bars (corroded and non-corroded) and the compressive tests on the pedestals show that the compressive strength of these elements is governed mainly by the geometric properties, but it is not significantly affected by the corrosion of the lower bars. Analytical models for strength assessment have to be diversified by considering plate type, and punched-governed or classic strut-and-tie models depending on the actual behavior at failure. The results show that the reduction in strength by corrosion is more evident in the lower specimens, with a reduction of the ultimate load of about 12%. The strut-and-tie model can be used effectively for heights equal to or greater than the element width, taking into account the variation of stress fields for tall pedestals, while punching and flexural models are more reliable for lower pedestals. Numerical FE models with nonlinear analyses confirm the results obtained with experimental tests and analytical methods.