Study on practical application of a new seismic damper using a Zn–Al alloy with a nanocrystalline microstructure

Superplastic Zn–Al alloy has some excellent properties needed for a seismic damper, such as high ductility, low work hardening and no harmful metal to human health. In addition, superplastic materials with ultra-fined grains exhibit the high-strain-rate superplasticity and/or low-temperature superplasticity. Some investigations were carried out for nano-sized Zn–Al alloy in order to develop a high-performance seismic damper capable of replacing conventional dampers, such as low-yield-point steel. First, the design for appropriate structure as a damping device using superplastic Zn–Al alloy was discussed by FEM analysis. Secondly, a bulk Zn–Al alloy with nanocrystalline microstructure was manufactured by thermo-mechanical controlling process (TMCP) technology, and the tensile properties of this alloy were compared with that of low-yield-point steel. Then, the full-size cyclic testing of the damping device was carried out in order to evaluate the response for earthquake. As a result, an ecological and high performance seismic damper, the so-called “maintenance-free seismic damper”, has been successfully developed and put into actual use in a high-rise building.