Earth matters, and carbon counts. Already in the design, specification and procurement stages, you can choose building materials with a lower carbon footprint than others. By taking action upfront and making the right material choices, you can make a dramatic impact on the climate change effects of a structure. Upgrading your steel choices to high-strength SSAB Weathering steel can help you take this giant step forward.
Upgrading your hollow structural steel sections with higher-strength sections in a new design can bring major weight savings.
Sustainable construction is emerging as a key consideration in structural design and lifelong maintenance. More, and more accurate, environmental product declarations are increasingly being requested. These will be a key competitive differentiator in the future. Also, the environmental challenge will drive updates of design codes and the implementation of optimized solutions.
Many industry stakeholders are realizing that controlling and regulating embodied carbon is vital for the industry’s ability to tackle climate change. But what exactly is embodied carbon? Let’s dig a bit deeper.
Embodied carbon can be defined as the amount of total greenhouse gas (GHG) emissions produced to get a construction asset into the operational stage. These emissions include extracting raw material, manufacturing, assembly and all transportation along the way. Added to these front-end emissions, maintenance, demolition, disposal and recycling also often fall within the scope of embodied carbon. Consequently, only operational carbon emissions are normally not part of the scope.
Embodied carbon is gaining increasing attention as industry and governments recognize that embodied carbon emissions are responsible for a large fraction of total emissions from the construction sector. Especially when looking at the infrastructure segment, where only little if any operational carbon is involved, embodied carbon represents the lion’s share of total emissions. Since the embodied carbon is so substantial, taking it into consideration early on in a project offers a valuable reduction opportunity.
High-strength steel enables you to use less steel in structural designs. This brings a corresponding saving potential in embodied carbon emissions – potentially up to 40-50% – so that investments in structural redesign needed for existing structures can really pay off.
SSAB has developed a wide range of weathering steel in yield strength levels up to 960 MPa, which enable lower steel weight of the structures even with typical corrosion allowances of weathering steel. This means that corrosion allowances needed for weathering steel don’t necessarily increase the weight, and when combined with high-strength grades the steel weight and related embodied carbon can be lowered, too. This opens new application possibilities especially in the thin range of 3-8 mm.
Recently, some high-strength weathering grades have been also standardized in Europe under harmonized products standards EN 10025-5:2019 and EN 10219-3:2020 for flat and tube products, and the steel structures made out of these grades can be also CE-marked by the customer.
Consequently, interest on the European market for this unique combination of weathering properties connected to high strength has been steadily rising.
Upgrading your hollow structural steel sections with higher-strength sections in a new design, like from S355J2H to SSAB Weathering Tube 500WH, can bring major weight savings, up to 23%. And along with this, savings in costs and a reduction in global warming potential of over 50%. The example scenario below shows you a basic comparison.
Grade: S355J2H. Dimension: 250 x 150 x 8. Surface treatment: hot dip galvanized (EN 1461).
Grade: SSAB Weathering Tube 355WH. Dimension: 250 x 150 x 8.5. Surface treatment: Patinated.
Grade: SSAB Weathering Tube 500WH. Dimension: 250 x 150 x 6.0. Surface treatment: Patinated.
Grade: SSAB Weathering Tube 500WH. Dimension: 300 x 100 x 6.0. Surface treatment: Patinated.
Disclaimer: ALWAYS VALIDATE THE UPGRADED DESIGN AND FOLLOW ALL APPLICABLE DESIGN RULES.
Calculations are made for same bending strength in main direction with corrosion allowance of 0.5 mm which is not considered in structural calculation.
Total cost savings may vary depending on the technical upgrade case and on steel and galvanizing prices.
GWP is based on Batch hot dip galvanized of steel products to EN ISO 1461 EUROPEAN AVERAGE, S-P-00915 vs. SSAB Structural hollow sections, S-P-02241
This example calculation for structural hollow sections was made for the same bending strength in the main bending direction of the beam. As a reference, a batch galvanized standard S355J2H hollow section was selected. The Upgraded A scenario presents the corresponding beam made out of SSAB Weathering Tube 355WH. Interestingly, both the costs and the GWP values are lower compared to the existing solution.
But even with the selected corrosion allowance of 0.5 mm for the weathering steel, the Upgraded B and C scenarios both made from SSAB Weathering 500WH would provide not only lower section weight but even bigger savings, both in costs and GWP value, compared with Upgraded A. When the stiffness in the main bending direction needs to stay on an equal level to the existing beam, the Upgraded C scenario can be the final selected solution.
The Technical Research Center of Finland, VTT, conducted a corrosion test for four different bridges made out of SSAB Weathering steel. This test provided performance data from real atmospheric conditions in Finland over a 32-year period. The results confirm that weathering steel´s general corrosion rates under C2 and C3 atmospheric conditions make them a good choice with minimal corrosion allowances. The tests also demonstrated that just within the first 5 years after commissioning, loss due to corrosion dropped drastically as the patina stabilized.
Think your next building project could benefit from SSAB Weathering steel? If you want a structure that delivers superior corrosion resistance and has a longer lifespan, lower life cycle cost and improved carbon footprint, SSAB Weathering steel might be the right choice for you. Feel free to explore our product information for structures and bridges, or contact our sales team.
