InfrastructureQuake experiments may lead to sturdier buildings
Johns Hopkins researchers will study how seismic forces affect mid-rise cold-formed steel buildings, up to nine stories high; the cold-formed steel pieces that are commonly used to frame low- and mid-rise buildings are made by bending about 1-millimeter-thick sheet metal, without heat, into structural shapes; these components are typically lighter and less expensive than traditional building systems and possess other advantages
Haybale house before successful shake table test // Source: thinkaboutit.eu
Cold-formed steel has become a popular construction material for commercial and industrial buildings, but a key question remains: How can these structures be designed so that they are most likely to remain intact in a major earthquake?
To help find an answer, Johns Hopkins researchers have been awarded a three-year $923,000 National Science Foundation grant to study how seismic forces affect mid-rise cold-formed steel buildings, up to nine stories high. The work will include development of computer models, as well as testing of two-story buildings placed atop full-size “shake tables” that replicate forces up to and greater than those of any modern-day earthquake.
Lead researcher Benjamin Schafer of the university’s Whiting School of Engineering said there is a critical need for the data these experiments should yield.
“We do have a conservative framework for how to build cold-formed steel structures to withstand earthquakes, but we don’t have all of the details,” said Schafer, the Swirnow Family Scholar Professor and chair of the Department of Civil Engineering. “Beyond avoiding complete collapse, we don’t know how a lot of building materials will be damaged when certain levels of earthquakes occur. Information gaps exist for a lot of building materials, but the gaps for cold-formed steel are really big. We’re trying to fill in some of those gaps in knowledge.”
The cold-formed steel pieces that are commonly used to frame low- and mid-rise buildings are made by bending about 1-millimeter-thick sheet metal, without heat, into structural shapes. These components are typically lighter and less expensive than traditional building systems and possess other advantages. For example, cold-formed steel pieces are more uniform than wooden components and do not share wood’s vulnerability to termites and rot. Cold-formed steel also is considered a “green” material because modern producers use 100 percent recycled metal.
Structural engineers who design cold-formed steel buildings need more information about how the material will perform during earthquakes, Schafer said, in part because of revised thinking in the construction industry.
“The old approach was to just make sure the building didn’t fall down in an earthquake, even if it was no longer safe or was too badly damaged to be used afterward,” he said. “Now, we’re focusing on what you can do to bring it up to a higher level of performance to make sure that the building can still be used after an earthquake, when desired.”
Some of the motivation for this is coming from the insurance companies and
