Testing of Cu-Based SMA Seismic Energy Dissipation Devices

Abstract eng:
This paper presents the results of a study on Cu-based shape memory alloys (SMA) elements for energy dissipation in connections under earthquake excitation. The elements include round bars for use as mechanical connectors and plates for ADAS-type energy dissipation devices. The goal of the study is to determine the behaviour of elements with full-scale dimensions, and evaluate possible scale effects on their shape memory or superelastic properties. Two nominal compositions of CuZnAl were used. The study of both compositions in parallel is of interest because of the large energy dissipation capacity of one and the self-centering capability of the other. Both materials may be combined to optimize the behaviour of connections that include elements made of these alloys. Bars of different diameters were fabricated using extrusion and hot-rolling. The mechanical properties (stiffness, martensitic transformation stress, tensile strength, ultimate strain) and equivalent damping of these bars were experimentally determined and their dependency on type, amplitude and frequency of excitation, and working temperature was studied. In addition, four annealed martensite plates (15x12x1 cm) were tested under cyclic out-of-plane flexure. Stable cycles and limited residual deformations were observed up to 20% drift. Equivalent damping ratio increased with larger drift, reaching a maximum of 8% for a 20% drift.

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