The National Science Foundation (NSF) has awarded $1.3 million to researchers developing a new structural system that will protect a building and its occupants during an earthquake, and allow for an immediate return to operability after the event. Researchers from the University of Illinois at Urbana-Champaign (Illinois), Lehigh University (Lehigh) and Oregon State University (OSU) will share the three-year, three-part award.
The grant to support this project, “Frame-Spine System with Force-Limiting Connections for Low-Damage Seismic Resilient Buildings,” is administered under the NSF program Engineering for Civil Infrastructure, part of the Division of Civil, Mechanical and Manufacturing Innovation. The project will include testing at an NSF-funded Natural Hazards Engineering Research Infrastructure (NHERI) facility.
The effort, led by Illinois Civil and Environmental Engineering professor Larry Fahnestock (pictured above), focuses on a system that combines the structural frame of a building with a rigid “spine” spanning multiple stories, joined by connectors that limit the transfer of force between the two elements. During an earthquake, the spine will distribute movement across the building to prevent concentrated damage, and the force-limiting connectors (FLC) will dissipate energy and reduce the impact of acceleration on interior contents. If successful, the new frame-spine-FLC system will result in safer and more resilient buildings that can return to use immediately after the earthquake is over.
“The fundamental idea behind a resilient structure is quick recovery after a major event, so in the big perspective, that’s what this project is about: developing a new approach for economical design of buildings that limits movement of the building and also prevents damage to occupants and contents,” Fahnestock said. “In particular, we are looking at critical facilities like hospitals where functionality after a major earthquake is essential for people’s lives and well-being.”
The project will integrate numerical simulations with experiments to comprehensively characterize the new system concept. Experimental work will include FLC tests in the United States at Lehigh’s NHERI Experimental Facility, and building tests in Japan. The team will develop and fabricate most of their system in the U.S., then ship components to Japan for the testing phase. There, they will collaborate with researchers at the 3D Full-Scale Earthquake Testing Facility (E-Defense) in Miki, Japan, operated by the National Research Institute for Earth Science and Disaster Resilience.
The E-Defense lab has the largest shake table in the world, which allows for testing of multi-story full-scale buildings. The researchers will take advantage of a previously constructed three-story building already on the shake table, adding a fourth story and connecting the spine and FLC components to the full structure. The building – complete with typical hospital equipment and fixtures on the interior – will then be subjected to ground acceleration recordings from historical earthquakes.
“We have a great opportunity to collaborate with a major research initiative in Japan – the Tokyo Metropolitan Research Project – and we are excited about testing at the E-Defense lab," Fahnestock said. "When we combine the experimental results from this international partnership, we will have an extensive dataset for dynamic structural and non-structural response of multiple high-performance building seismic systems.”
By the end of the project, Fahnestock said the team hopes to have developed their new system in a way that is not only technically feasible but also economical and easy to implement. Industry partnerships will facilitate technology transfer and application to seismic building design, and the project experimental data will contribute to advancements in computational modeling for seismic performance assessment.
In addition to Fahnestock, the team includes Richard Sause and James Ricles of Lehigh and Barbara Simpson of OSU. They are partnering with the American Institute of Steel Construction for materials, fabrication and additional funding. Other collaborators include practicing engineers in the U.S. who will serve as design consultants and advisers, researchers at Kyoto University and Hokkaido University in Japan, and Nippon Steel.
Update | December 21, 2020
Researchers conducted full-scale building earthquake simulations on the shake table at the Hyogo Earthquake Engineering Research Center (E-Defense).