Northumberland Strait bridge: analysis techniques and results

Abstract

The Northumberland Strait at the Atlantic coast of Canada will be crossed by a 13 km bridge. The major part of the superstructure will consist of 44 spans, each of length 250 m and a box cross section of variable depth 4.5–14 m. The superstructure, divided into units of maximum length 192 m, will be produced in a yard by segmental casting and multistage prestressing. These units will be assembled at their final position on top of the piers. Each pier is composed of two pieces, also produced in the yard and connected on site by cast in situ concrete. This paper describes selected analysis problems and their solutions employed in the structural design. The analysis problems are concerned with (i) dynamic response to ice forces; (ii) movements of pier footings and stiffness of the subgrade; (iii) variation of stresses and deformations during construction and during the life of the structure, considering the effects of creep and shrinkage of concrete and relaxation of the prestressed steel; and (iv) thermal stresses. Key words: bridges, concrete, creep, prestress relaxation, segmental construction, shrinkage, strait crossing.