CHARACTERIZATION AND OPTIMIZATION OF SHAPE MEMORY ALLOY BEHAVIOR FOR SEISMIC VIRBATION CONTROL APPLICATIONS IN BUILDINGS
One means of developing self-centering structural systems for seismic applications is through the use of materials with inherent recentering capability. Superelastic NiTi shape memory alloys are one such metallic alloy which can undergo large deformations while returning to its original shape upon unloading. To explore their feasibility for structural applications, tension-only, quasi-static cyclic tests to a constant strain level and dynamic cyclic tests with non-uniform strain cycles were preformed on large diameter NiTi bars. Unlike past studies, hot-rolled, rather than cold formed, large diameter bars were considered as a more cost effective alternative. The results showed that residual strain levels remained below 1% even after 20 cycles at 6% strain. However, equivalent viscous damping values also remained below 4%. Dynamic loading rates caused an approximate 5°C increase in the surface temperature of the bars resulting in a further decrease in the damping capacity, but no significant effect on the residual deformation values were observed. To further optimize the cyclic properties of NiTi shape memory alloys, a mechanical training study of NiTi wire specimens was also undertaken. Mechanically training the wire specimens for 40 cycles to 6-7% strain stabilized the properties in terms of the forward transformation stress, residual strain, and equivalent viscous damping. In general, the results of this study suggest that large diameter NiTi superelastic shape memory alloys are a viable material for the development of self-centering structural systems for earthquake mitigation applications.
shape memory alloys self-centering residual strain mechanical training damping
Jason McCormick Reginald DesRoches
Assistant Professor, Department of Civil & Environmental Engineering ,University of Michigan,Ann Arb Professor, Department of Civil & Environmental Engineering, Georgia Institute of Technology,Atlanta,
国际会议
14th World Conference on Earthquake Engineering(第十四届国际地震工程会议)
北京
英文
2008-10-12（万方平台首次上网日期，不代表论文的发表时间）