Performance-based seismic design is on a roll, thanks to recent, first-of-their-kind shake-table tests that proved the viability of a “rocking” braced frame that moves seismic design beyond life safety toward build-for-repair. The steel frame not only survived shaking that was 1.75 times stronger than the Northridge earthquake, it returned to its original plumb position after shaking, thanks to post-tensioned strands. Damage was limited to a replaceable fuse, as planned.
The objective of the research is to develop tools for seismic engineers to design structures for repair, says Gregory G. Deierlein, lead investigator for the $1.4-million project, called “Controlled Rocking of Steel-Framed Buildings With Replaceable Energy-Dissipating Fuses,” funded primarily by the National Science Foundation. “The structure will be safe, intact and plumb” after a major quake, adds Deierlein, director of the John A. Blume Earthquake Engineering Center at Stanford University, Stanford, Calif.