Structural performance of prestressed concrete bridge piles using duplex stainless steel strands

The use of duplex high-strength stainless steel (HSSS) Grade 2205 prestressing strand and austenitic stainless steel (SS) Grade 304 spiral wire reinforcement is proposed for reinforcing prestressed concrete piles in marine environments in order to provide a 100+ year service life. The study experimentally investigated 40.6-cm-square, 21.3-m-long piles, which were successfully driven to refusal without visible damage, extracted, and tested in flexure and shear. Flexural and shear strength of piles using duplex HSSS 2205 strands were greater than predicted by design specifications. Experimental prestress losses for piles using duplex HSSS 2205 strands were approximately 80% of the predicted losses by standard provisions and were not affected by pile driving and extraction. These findings indicate that duplex HSSS 2205 can be used for prestressing strands in combination with austenitic SS 304 for the transverse confinement and shear reinforcement for prestressed concrete piles, using the same design requirements and construction procedures used for conventional prestressing strand and wire reinforcement.