Proceedings of the 29th Annual Conference on Deep Foundations, 2004, Vancouver, British Columbia, Canada "Emerging Technologies", (DFI)
Design and Construction of Integral Drilled Shaft – Columns for the Boscawen-Canterbury Bridge
Frederick C. Rhyner, John Byatt, Erin F. Wood, Jeffrey Cicerello, John R. Roma
Drilled shafts have become an economical foundation choice for bridges in the northeast United States, especially when they can be constructed over water without the use of cofferdams. For the Boscawen-Canterbury Bridge over the Merrimack River in New Hampshire, an unusual design was used to avoid the used of cofferdams and avoid the need for pier caps at the waterline. This design used a pair of integral drilled shift – columns to form a bent type of substructure for support. Drilled shafts were 8-foot diameter, about 90 feet deep, with 16-foot long rock sockets. These are integrally constructed with 6-foot diameter reinforced concrete columns extending 37 feet from the water line to the superstructure. Design load cases focused on lateral loads from ice flows, stream flows, wind and seismic events. Alternative analyses using different methods were made to check the design results. This paper discusses the subsurface conditions, design of the drilled shafts and columns, rebar and joint detailing issues, and construction of the drilled shafts.
|article #1252; publication #68 (AM-2004)|