WASHINGTON, D.C. – The American Iron and Steel Institute (AISI) has completed the first phase of a three-phase research program that will help fill a knowledge gap in understanding how cold-formed steel (CFS) members, connections and systems in a building perform during an earthquake. The research is being conducted by a team from the Structural Engineering and Materials Program at Virginia Tech, and the results of the first phase are published in a report titled: “RP13-2: Energy Dissipation of Thin-Walled Cold-Formed Steel Members.” A free download is available here (86 pages).
Traditional analysis and design procedures for cold-formed steel light frame buildings subject to earthquakes tend to focus on utilizing the strength of individual shear walls or diagonal flat strapped braced walls, which is adequate for providing protection against collapse during design-level seismic events. However, in order to make buildings more resilient and cost-effective, researchers need to better understand how the individual components making up these walls contribute to the performance of the whole structure.
Measuring how these individual components perform during seismic testing allows researchers to develop more accurate and computationally efficient design models. This first phase of the research examined the cyclic behavior and energy dissipation of cold-formed steel C-section structural axial and flexural framing members. Twenty-four axial tests and 24 flexural tests were performed to evaluate the energy dissipation characteristics of axial and flexural members experiencing global, distortional and local buckling deformations.
“The resulting data from this research was used to calibrate a hysteretic model that represents the full response of cold-formed steel C-section structural framing members,” said Bonnie Manley, P.E., Regional Director, Construction Codes and Standards and leader of AISI’s Seismic Code Team. “From the model, we are developing a toolbox of nonlinear elements that are capable of accurately simulating the seismic behavior of CFS members and their infinite number of possible configurations in cold-formed steel structures. The remaining two phases of the program will focus on connections and systems. When those are completed, the toolbox will be fully stocked with a suite of models that will greatly improve the accuracy of seismic analysis and performance-based earthquake engineering of CFS structures. The end result will be safer buildings and more design flexibility for design professionals.”
“RP13-2: Energy Dissipation of Thin-Walled Cold-Formed Steel Members” includes:
- A review of available literature that explores the cyclic behavior of axial and flexural members experiencing buckling,
- A description of the testing program,
- A summary of the experimental results of cyclic and monotonic tests of CFS axial and flexural members exhibiting local, distortional and global buckling, and
- The calibration of a hysteretic model that represents the cyclic response of CFS members.
AISI’s codes and standards work is conducted under the Construction Market Council of the Steel Market Development Institute (SMDI), a business unit of AISI, which oversees the industry’s investment in advancing the competitive use of steel by meeting the demands of the marketplace. For more information on SMDI’s Construction Market program, visit www.smdisteel.org.