SBIR-STTR Award

Several properties displayed by members of the shape-memory family of alloys, including: (1) shape-memory based on a temperature induced phase transformation; (2) pseudoelasticity based on a stress induced phase transformation (3) excellent fatigue and corrosion resistance, can be exploited individually and in combination to provide both active and passive aseismic control for all sorts of structures. Active, passive, or combined active/passive devices can control both structural stiffness and damping in open loop or closed loop control schemes. Device types include linkage devices, modified joint devices, modified member devices. This study will develop this promising aseismic technology by providing: (1) materials characterization for all relevant alloys including shape-memory, pseudoelasticity, and fatigue behavior, thermomechanical processing, etc. (2) actuator characterization for all device types including actuator force, actuating mechanism, control characteristics including dynamic response, reliability, cost, and expected life. (3) a demonstration of the most promising device for a framed structure on a small scale shake-table facility.

In recent years there has been a growing shift in earthquake-resistant design philosophy, from the conventional "life-safety" approach to performance-oriented and damage-control approaches. Providing a structure with the capability to dissipate large amounts of energy in a controlled and stable manner is one very effective means to achieve a performance-base design. Key requirements of any such energy dissipation (or damping) system are that it be reliable, perform stably, have low temperature and frequency dependencies, fatigue-resistant, and above all be predictable for design purposes. Shape-memory alloy damping systems encompass all of these features. Phase I results indicate that SMA damping concepts are very promising for passive seismic energy dissipation. This Phase II program involves the development of prototype SMA dampers, systems-level earthquake simulator tests of non-ductile reinforced-concrete and ductile steel frame structures incorporating SMA devices, and complementary analytical and parametric studies. A design guideline, which will synthesize the overall understanding of passive energy dissipation for building seismic design, and SMA devices in particular, will be prepared.