ABSTRACT
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. 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. 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. 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.
