Residual strength assessment and destructive testing of decommissioned concrete bridge beams with corroded pretensioned reinforcement

Abstract

Destructive tests were performed on 19 decommissioned pretensioned concrete bridge beams that had corroded pretensioned reinforcement. The beams were obtained from the 1969 Tiwai Point Bridge in Southland, New Zealand, which experienced chloride-induced corrosion caused by sea spray that resulted in the superstructure’s being decommissioned and removed in 2009. Destructive flexural testing results were compared with thorough nondestructive condition assessments and with post-test breakouts of reinforcement. The beams tested ranged from good-condition beams to those with severe corrosion in 4 of the 21 prestressed strands. The most severely corroded beam sustained 69% of the load of an equivalent good-condition beam. A proposed methodology for the assessment of the residual strength of beams with corroded pretensioned reinforcement was shown to provide an effective means of estimating the number of corroded strands that should be disregarded in the calculation of the residual strength.