Experiments on prestressed concrete decks in two-girder composite bridges

Two-girder composite bridges are generally known to have high economical efficiency compared to the multi-girder bridges. However, as spacing between girders has to be increased, thickness of the deck also needs to be increased. According to Korea Highway Bridge Design Code (KHBDC), the deck thickness should be more than 30 cm. Using the transversal prestressing strands in concrete deck, we can reduce the depth about 10%. However, there is little experience on the design and construction of prestressed concrete (PSC) decks in Korea. This research focuses on the behaviors of PSC deck. Considering the characteristics of the two-girder bridge and the construction conditions in Korea, a cast-in-place PSC deck is recommended for the two-girder bridge with girder spacing of 6 m. To examine its structural behaviors, three real scale partial model deck specimens (3 m × 5 m) are fabricated and tested. Two H-beams are attached to both longitudinal sides of specimens by bolting to simulate the plate behavior and longitudinal continuity of bridge decks. The stiffness of the H-beams is determined by analyses such that moment distributions of specimens are equal to those of real bridge model. A series of static tests is carried out to find out the elastic behavior, cracking load, and ultimate behavior of the decks. Finite element analyses and rigid plastic analyses are performed to verify the experimental works. Several design considerations for the design of PSC decks are discussed.