Precast, prestressed concrete bridge girders have become longer, increasing the likelihood of a stability failure. Understanding the stability behavior of prestressed concrete bridge girders on flexible supports entails the consideration of the deformation of the girder, the initial imperfections of the girder, the initial support rotation, and the rotational stiffness provided by the bearing pads. An experimental study on the rollover behavior of a 100 ft long (30 m) PCI BT-54 prestressed concrete bridge girder was performed. Qualitative conclusions were derived from the experiments, and a comparison was made to a nonlinear analysis and to the current method for calculatingfactor of safety against rollover. The experimental and analytical study showed a high sensitivity to the end support conditions. Recommendations were made for increasing the rollover stability of prestressed concrete bridge girders and for values to assume in the modeling of the support conditions and member imperfections when performing stability analyses.
