C. J. Black, I. D. Aiken, Seismic Isolation Engineering, Inc., Oakland, CA; R. Krumme, E*Sorb Systems, Berkeley, CA; J. Hayes, S. Sweeney, U.S. Army CERL, Champaign, IL
Since the early 1990s, a growing body of work has been devoted to investigating the use of shape memory alloys (SMAs) for enhancing the seismic resistance and performance of structures. SMAs possess a number of characteristics, unique among metals, that make them particularly attractive for seismic resistance: they are capable of large nonlinear deformations (which in the case of superelastic alloys are nonlinear elastic), have good energy absorption capabilities, and are able to sustain large cyclic deformations with essentially no loss in performance. This paper presents a material characterization program that includes the experimental testing of NiTi specimens with force capacities consistent with the requirements for applications to building structures. The large diameter specimens (up to 2.5 inches) tested as part of this study include annealed martensite and superelastic SMAs, as well as, large-diameter cold-worked martensite and cold-worked (linear) superelastic bars. The results demonstrate that large-diameter shape memory alloy bars will exhibit the superior force-deformation characteristics typical of smaller sized SMA components, which have lead to their relatively wide-spread use in other industries.
Since the early 1990s, a growing body of work has been devoted to investigating the use of shape memory alloys (SMAs) for enhancing the seismic resistance and performance of structures. SMAs possess a number of characteristics, unique among metals, that make them particularly attractive for seismic resistance: they are capable of large nonlinear deformations (which in the case of superelastic alloys are nonlinear elastic), have good energy absorption capabilities, and are able to sustain large cyclic deformations with essentially no loss in performance.
This paper presents a material characterization program that includes the experimental testing of NiTi specimens with force capacities consistent with the requirements for applications to building structures. The large diameter specimens (up to 2.5 inches) tested as part of this study include annealed martensite and superelastic SMAs, as well as, large-diameter cold-worked martensite and cold-worked (linear) superelastic bars. The results demonstrate that large-diameter shape memory alloy bars will exhibit the superior force-deformation characteristics typical of smaller sized SMA components, which have lead to their relatively wide-spread use in other industries.
