Title: Flexural Behavior of Concrete Bridge Girders Prestressed with Stainless Steel Strands
Author(s): Anwer Al-Kaimakchi and Michelle Rambo-Roddenberry
Publication: Structural Journal
Appears on pages(s): 137-152
Keywords: corrosion-resistant strands; flexural behavior; full-scale girders; prestressed concrete; stainless steel strands
Corrosion-resistant stainless steel strands are an alternative to carbon steel strands in prestressed concrete structures, particularly in extremely aggressive environments. The benefits of using stainless steel strands include prolonged service life and fewer inspections of the structure. The flexural behavior of stainless steel prestressed concrete girders was experimentally studied. Seven full-scale 42 ft (12.8 m) long AASHTO Type II girders were designed, cast, and tested in flexure. Two of the seven girders had carbon steel strands and served as control girders. Experimental results showed that the overall flexural behavior of the girders prestressed with stainless steel strands is different than those prestressed with carbon steel strands. The capacity of all stainless steel girders increased up to failure, which reflects the stress-strain shape of the stainless steel strands. When the girders had the same initial prestressing force, the ultimate capacity of the stainless steel non-composite and composite girders was approximately 11.7% and 23.7% higher than that of the control girders, respectively. Experimental results revealed that regardless of failure mode, the girders prestressed with stainless steel strands can achieve ultimate capacity and deformability as high as those prestressed with carbon steel strands. Although the composite stainless steel girders failed due to rupturing of strands, they failed at a noticeable deflection with many flexural cracks in the midspan. Rupture of strands failure mode is particularly important because it demonstrates the importance of the ultimate strand strain in design. The guaranteed ultimate strain of stainless steel strands is 1.4%. Stainless steel prestressed concrete I-girders are recommended to be designed to fail by rupturing the strands. The analytical load-deflection curves showed good agreement with experimental ones. A simple numerical design procedure was developed to predict the nominal flexural resistance of stainless steel pretensioned girders designed to fail by rupture of strands.