Evaluation of Cracks in a Large Single-Cell Precast Concrete Segmental Box Girder Bridge without Internal Struts

The Hathaway Bridge, an eastbound and westbound bridge pair, is located in Panama City, Florida. Each of the pair consists of a single-box precast concrete segmental girder with a deck width of 24.4 m (80 ft). The lengths of the eastbound and westbound bridges are 1,031.43 and 1,162.93 m (3,384 and 3,815 ft), respectively. To date, these are the largest single-cell precast segments without internal struts fabricated in the United States. During construction, many web cracks developed in the external anchorage areas. The purpose of this investigation is to identify the main causes of the cracks and provide some design recommendations for large precast concrete segmental box girders. First, a brief description of the bridge is given. Then, analytical models for the bridge, posttensioning forces, and construction forces are presented. The analytical results show that the external longitudinal posttensioning forces can cause significant high-tensile stresses in the interior face of the web around the anchorages. The information presented in this paper can assist bridge engineers in the design of concrete segmental box girder bridges.