Design and testing of corrosion damaged prestressed concrete joists: the Pescara Benchmark

Abstract

An experimental campaign named the Pescara benchmark and devoted to study the dynamic behaviour of corroded p.c. joists has been conducted. The steel corrosion reduces the area of the reinforcement and causes cracking of concrete so that r/c members are subjected to loss of strength and stiffness. It is of interest to evaluate the corrosion level at which the damage can be detected through signal processing procedures and how close such level is to the r/c member safety limits. Joists of current industrial production having different steel to concrete ratios are tested in different laboratory conditions. Dynamic tests involve either free vibrations and forced vibrations due to a moving mass simulating actual traffic loads in railway bridges. The paper discusses the rationale of the tests including the set up of the artificial corrosion, the static characterization of the joist and the dynamic tests in the different stages of corrosion experienced.

On the Effectiveness of Vibration-Based Monitoring for Integrity Management of Prestressed Structures

“…Due to the closing of the cracks caused by the prestressing, only slight changes of the modal frequencies were detected before the yielding of reinforcement. Similar conclusions are reported in the works by Capozucca [10] and Di Evangelista et al [11]. Negligible variations of modal frequencies are also reported in [12] for beams prestressed by external tendons and tested with impact hammer tests.…”

Damage detection in a post tensioned concrete beam – Experimental investigation

“…The possibility to detect prestress losses from variations of modal frequencies was investigated also in the paper by Saiidi et al [5] who concluded that the variations of frequencies induced by changes in the prestress in practical ranges are too small to allow a reliable estimation of the prestress losses. Similar conclusions are reported in references [7], [8] and [9] where the variations of the modal frequencies with corrosion are experimentally assessed for prestressed concrete beams. In all these studies very small variations of the modal frequencies are reported for low to medium level of corrosion induced cracking of the concrete.…”