Investigating the extension of service life of box-beam bridge girders

Abstract

The main motivation within this thesis is to explore the possibility of increasing the service life of box-beam bridge girders to aid the ambition of the Dutch government to become a circular economy. The construction industry still follows a more or less linear economy system. Many bridges in the Netherlands are approaching the end of their service lives, and efforts are being made to extend the lives of these bridges. This is but a temporary solution, and these bridges will require replacement within 20-30 years. This provides an opportunity to incorporate circularity within new and upcoming structures from the design phase onward rather than only as an end-of-life practice. Therefore this thesis explores the possibilities of incorporating the strategy of lifespan extension, in the form of a cover increase against chloride-induced corrosion. The exact increase was calculated through the use of a relevant service life design model (DuraCrete) and compared with the Eurocodes. The reliability of the model was checked using a Monte Carlo simulation. Subsequently, the circular aspects of future adaptability were also investigated considering a fictitious scenario of increased traffic load. Hence, it was concluded that a marginal increase in concrete volume and prestressing steel per beam would allow for a more durable and adaptable beam for the future.