A913 steel offers critical advantages over A992, which can impact how architects design buildings
It’s easy to leave steel decisions to the engineer. But, as AIA partner Nucor explains, there are two primary benefits to A913 steel—efficiency and sustainability—that architects should know and understand.
There are two compelling benefits of ASTM A913 steel that every architect should know: It’s both efficient and sustainable. So why aren’t more specifiers using A913 in their projects? They don’t know about it.
For reference, the ASTM grade of steel typically used for column sections is A992, which has a yield strength of 50 KSI (kips per square inch). A913 is a higher-strength steel most commonly available with a yield strength of 65 KSI.
The efficiency of any structural element breaks down into two parts: Weight and space.
At a basic level, a column must be strong enough to support the load applied to it. A913’s refined metallurgical properties yield a higher capacity for the same amount of steel when compared to A992. This means that a smaller A913 Grade 65 column can support the same load with less material, thereby reducing the necessary weight of the column. Not only is the weight reduced in this scenario, but the total area of the column section is also smaller.
On average, column designs using A913 Grade 65 provide a 15% to 25% reduction in steel weight versus a comparable A992 section. Here’s a simple example for a column supporting an axial load of 6,000 kips (1 kip = 1,000 pounds) with a 13-foot floor height. Using A992 steel, a W14x500 column is required. With A913 Grade 65 steel, a W14x398 is required, resulting in a weight savings of 1,326 pounds for one 13-foot column. If there are 40 similar columns on the project, that equates to a material savings of more than 53,000 pounds just by using the higher-strength steel.
Now let’s look at space. A 10-ksi concrete column of similar capacity to the steel columns above would require a 36-inch square cross-section. In this example, the steel column footprint uses 65% less area than the concrete column. As designers, the efficient use of space and material is critical to designing a sustainable building.
The use of A913 steel complements the sustainability goals of our industry by reducing the weight of structural members, in turn reducing a building’s carbon footprint. Lighter members also lead to secondary reductions including smaller foundations and smaller crane capacity requirements. Even further, it means reducing the architectural finishes required to encapsulate the structural elements.
AEOS A913 steel
Nucor is North America’s sole producer of A913 steel, AEOS. AEOS is made using in-line Quenching and Self Tempering (QST) technology, which allows A913 to be manufactured within the same rolling schedule as A992 steel. And because the production process is very efficient, the weight savings in material almost always overtakes the minimal cost premium.
Nucor is currently exceeding the emissions targets set by the Paris Agreement, and currently operates well below the global industry average. If all the world’s steel was produced the way Nucor makes steel, it would eliminate more than 2 billion tons of greenhouse gasses (GHG) every year. This is the equivalent of grounding the entire airline industry twice. Nucor has committed to an additional 35% reduction in GHG by 2030.
Visit Nucor Construction Solutions to learn about AEOS as you consider high-strength steel on your next project.
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