12 August 2024
IALCCE – Melbourne 2025
Abstract
Building Systems Using Seismic Fuses with Advanced Material and Friction
Mark Sarkisian, PE, SE, NAE, LEED
Partner – Skidmore, Owings & Merrill (SOM)
The introduction of friction devices in superstructures has proven to be an effective method of dissipating energy during seismic events while protecting the base building from damage with little or no repair required following strong ground motions allowing structures to remain essentially elastic in major seismic events. With new developments, it has been proven that advanced materials such as Shape Memory Alloy (SMA) can also be designed to “fuse” during these extreme events. Life safety objectives are met, and high performance is achieved while minimizing business interruption and embodied carbon that would be required for repair or replacement of structural elements / systems.
Shape Memory Alloy with its super elastic characteristics and traditionally used for medical devices such as artery stints has been conceived as a seismic fuse dissipating energy during an earthquake and returning to its at-rest position. Nitinol, a combination of nickel and titanium, is an alloy that has super elastic characteristics without the need for heat to allow the material to experience a phase change.
Friction devices can be installed into steel, concrete, composite, and even timber structures to create ductility and can be done at all scales of structures including buildings and bridges. For shorter structures, building periods are lengthened with mechanical sliding behavior of joints through temporary softening of the structure. With this softening, less inertial forces are attracted to the structures during an earthquake. High strength bolts are typically used to create the fuse joints while using well-defined friction materials. With the coefficient of friction known and clamping loads understood, the threshold of slip is well-understood and predictable.
Research has been extensive including component SMA and friction tests, dynamic loading of components, and full-scale testing of joints and frames. A summary of this testing will be given along with an actual application of the technology into a high-rise structure. Friction systems for steel, concrete, and timber will be described.