Less is More: Geometric Cutouts May Enhance Steel Performance

Matthew Eatherton at Virginia Tech's Thomas M. Murray Structural Engineering Laboratory. (Photo: Logan Wallace / Virginia Tech)

While working as a structural engineer in California, Matthew Eatherton saw myriad ways the structural steel industry could delve into the then-burgeoning fields of subtractive and additive manufacturing – the latter commonly referred to as 3D printing – and improve building performance.

Now an assistant professor with Virginia Tech’s Charles E. Via Jr. Department of Civil and Environmental Engineering, Eatherton will be using a five-year, $500,000 National Science Foundation CAREER Award to research how steel plates with carefully designed geometric patterns - or voids - cut into them can better withstand everyday loads and extreme events (high winds, blast or shock from an earthquake) than the standard solid steel plates currently used. The research work builds on an earlier American Institute of Steel Construction (AISC) award, the Milek Faculty Fellowship grant. Eatherton received the fellowship for the years 2012 – 2015, supporting his research on buckling-resistant steel plate shear walls.

“We have a unique opportunity to advance the industry and improve performance,” Eatherton said of steel-framed buildings subjected to earthquakes and other hazards.

A Virginia Tech College of Engineering faculty member since 2010, Eatherton said advancements in water-jet and laser cutting technology in subtractive manufacturing, where material is removed from a structural component, and the growing use of 3D printing in additive manufacturing, were “not being used to their potential in the steel industry.”

Steel buildings are designed to flex without fracturing as they absorb extreme lateral loads from earthquakes or high winds, a property known as ductility. Eatherton’s solution is to “improve ductility and energy dissipation ability by strategically removing material from the plates rather than adding more material.” By introducing small cutouts – ring-shaped, butterfly-shaped, etc. – global shear deformations in steel plates can be converted into smaller ductile mechanisms that resist buckling and increase stiffness within steel structures.

Investigation by Eatherton and his research team will include computational modeling and physical experiments, both in reduced-scale and then full-sized steel components, at Virginia Tech’s Thomas M. Murray Structural Engineering Laboratory. As part of the CAREER Award, Eatherton will be able to fund two civil engineering doctoral students to work on the project in addition to another doctoral student already working on the research.

Development of the design approaches will take years, possibly beyond the five years outlined in the NSF Award, to be incorporated in U.S. building codes. “You can never test enough configurations,” said Eatherton.

Eatherton, who worked as a structural engineer from 2001 until 2006 in earthquake-prone California, has also teamed with faculty within the Virginia Tech College of Architecture and Urban Studies to explore the use of exposed geometrically cut steel plates in building interior designs to serve both structural purposes and architectural form in terms of screening and aesthetics. The research also draws from Eatherton’s doctoral research at the University of Illinois at Urbana-Champaign.