Experimental Investigation on the Residual Flexural Behavior of 28-Year-Old Decommissioned Prestressed Concrete Voided Slab Girders

The residual flexural behavior of semilightweight prestressed concrete voided slab girders taken from a decommissioned 28-year-old bridge near Barrhead, Alberta, Canada was investigated. The residual flexural behaviors under loads corresponding to the serviceability limit state (SLS), the ultimate limit state (ULS), and the failure state were evaluated using four-point bending tests. Four girders with different deterioration levels were tested, with one girder exhibiting no visible deterioration considered as the control girder. Material tests on concrete, mild steel reinforcement, and prestressing strands were conducted to better understand girder behavior. Strand corrosion reduced the girder flexural strength by 14%–22% and changed the failure mode from concrete crushing after steel yielding to undesirable strand rupture prior to yielding. However, all girders, regardless of deterioration level, showed satisfactory performance under SLS and ULS loads. The effective prestress force was also studied using digital image correlation (DIC). North American bridge design codes were used to predict the cracking load and flexural strength considering the influence of different corrosion effects. Steel area loss was shown to be the most important factor for both cracking and flexural capacity reduction.