The paper summarizes the latest research on how to design lightweight and slender structures that cost the same to build as carbon steel bridges but don’t corrode.
It covers two techniques with huge potential to save public funds, as thousands of road and rail bridges built during the 20th Century now need extensive maintenance and repair or replacement.
Paul Janiak, Research and Development Manager, says: “Some organizations have cut maintenance costs by building stainless steel bridges for critical sites. However, there is a misconception that these are expensive – because although stainless steel is more costly per tonne, it provides better value over the long term when compared on a Life Cycle Cost basis.
“The goal of our research was to give bridge builders the tools to make stainless steel more competitive from day one.”
Road and rail bridges
Choosing a high-strength, duplex stainless steel enables structural engineers to create slender and lightweight beams that can support the same loads as standard i-beams made from carbon steel that have a much larger cross section. And because stainless steel also has excellent corrosion resistance, the beams will last for decades longer.
According to findings in the white paper, it’s possible to design stainless steel i-beams for road bridges with 25 to 50 percent less material than with carbon steel. When deployed in a full-scale bridge project, it becomes cost-comparable to a traditional carbon steel bridge.
Railway bridges need an alternative approach to take account of fatigue caused by cyclic loading from heavy rail vehicles. The researchers found a potential weight saving of 33 to 39 percent by using post-weld treatment. This makes the capital cost of a railway bridge only a little higher than the traditional approach. However, the cost difference is marginal compared with the lifetime savings from eliminating maintenance and track closures.
Janiak adds: “We’ve written the white paper to help managers at transport agencies and engineering designers quickly understand what’s possible in terms of structural design and post-weld treatment, and how that translates into real-world savings.”
The white paper is based on the findings of the Sustainable Infrastructure through increased use of Stainless Steel (SIFRA) project led by the Swedish transport agency Trafikverket with partners from industry, academia and government.