Model Study of New Standard Prestressed Concrete Bridge

In a recent report to the Ontario Precast Concrete Manufacturers Association, a firm of consulting engineers recommended the adoption of a new standard precast concrete trapezoidal box section bridge girder. This section is intended to replace standard I-section girders in spans of 100ft-150ft (30.5m to 45.8 m); and is being used for the first time in a proposed two-span continuous underpass structure. A 1/4.80 scale direct model study conducted on the negative moment region of the proposed structure is presented in this paper, particular emphasis being placed on the interface section between the precast girders and the in-situ concrete pier cap. Modeling criteria, materials, techniques and certain distortions allowed in the study are examined. Based on the study, a recommendation was made for the reduction of 11% in the level of longitudinal post-tensioning. Satisfactory performance of the prototype interface and pier cap sections can be expected under working and ultimate load conditions.