An analytical study was carried out to determine whether and how much the performance of continuity connections for precast, prestressed concrete girders with cast-in-place decks is affected by positive moment reinforcement in continuity diaphragms. A flexibility-based analytical tool is developed that predicts time-dependent restraint moments and the effectiveness of the continuity connection under service live loads. The model considers the different nonlinear stress-strain responses of the continuity diaphragm and the girder/deck composite sections, and the change in the stiffness f the structure under time-dependent effects. The study confirms previous findings that total midspan moments are virtually independent of the amount of positive moment reinforcement provided. This, however, does not mean that positive moment connections are unnecessary. Cracking of the diaphragm in the absence of such connections significantly reduces the effectiveness of continuity for service live loads and may raise durability concerns. Based on the analytical results to date, a minimum amount of positive moment reinforcement is recommended to avoid a significant loss of continuity and to control cracking of the diaphragm under service loads.
