Problems with Continuous Spliced Posttensioned–Prestressed Concrete Bulb-Tee Girder Center Spans at West Point, Virginia

Abstract

The Lord Delaware and Eltham Bridges carry traffic on US-33 over the Mattaponi and Pamunkee Rivers in Virginia. Completed in 2006 and 2007, respectively, the bridges are similar in that they have prestressed, precast tee-beam approach spans and two four-span continuous spliced posttensioned–prestressed precast bulb-tee girder center spans. Constructed with the latest prestressed–posttensioned precast technologies, the structures were expected to provide relatively maintenance-free performance for more than 100 years. In May 2015 during a biannual inspection, a spall that exposed a tendon duct was reported in the web of an exterior girder of the Lord Delaware bridge, raising concerns about the life of the of the posttensioned lightweight concrete girders. The tendon grout was a high-performance prepackaged mixture. In-depth inspections identified cracking, leaking, and spalling in the webs of the beams and problems with the grouted tendons that included voids, soft grout, water, and corroding strands. Ground-penetrating radar worked well to locate the tendons, and impact echo worked well to determine the condition of the grout. Destructive drilling and sampling were used to confirm the impact echo readings and to evaluate the condition of the grout. Access to the strands at the anchors and over the piers where voids are typically located was not possible because at the anchors the web thickness was the same as the flange, and over the piers the tendons were in the top flange of the beams. A suitable repair has not been determined.