16.12: Winning steel solution for flat arch bridge

Abstract

As part of a new University Campus development in the city of Northampton (UK), a new road access bridge was required to span over the river Nene. The client's aspirations and the planning requirements were set to keep the character of the existing landscape while creating an appropriate landmark structure for the new campus. The client's specimen design included a concrete flat arch bridge spanning 49m with a shallow rise of 3.7m above the navigable channel of the river. During the tender design competition, closer reviews of the concrete solution were undertaken by the design and build team, concluding that the imposed loads to the foundations and the construction method required to build the concrete deck would not prove to be economical. Thus, an alternative design was developed using a steelconcrete composite structure. The awarded solution includes 220 tonnes of welded steel plates to form a shallow and flat arch structure with deck cross girders. This bridge case study paper discusses the design aspects from development at planning phase to tender design and detail design as well as the specific construction stages related to the steelwork erection.