Inelastic behavior of a continuous composite box-girder bridge with prefabricated slabs

For the construction of open-topped steel box girder bridges, prefabricated concrete slab could offer several advantages over cast-in-situ deck including good quality control, fast construction, and elimination of the formwork for concrete slab casting. However, precast decks with unreinforced joints should be designed to prevent the initiation of cracking at the joints, because the performance of the joint is especially crucial for the integrity of a structural system. In this paper, experimental results on a 20m-20m continuous composite bridge model with precast decks are presented. Internal tendons and external tendons were used to prevent cracking at the joints. Judging from the inelastic behavior of the bridge model, external prestressing in negative moment regions could offer befter performance in terms of cracking and flexural stiffness. Simple plastic analysis was carried out to estimate the ultimate flexural capacity of the continuous bridge, and the incremental prestress of external cables after cracking was estimated.