Each wire passes through four steel hooks which
are welded at each corner of steel plates. In such a configuration,
the induced strain along the SMA wire due to the cyclic lateral displacement
of rubber bearing noticeably decreases since one continuous
wire is used instead of four wires fixed at each corner of
the supporting plate.
The total length of the SMA wires (LSMA) required for the
straight configuration in each aspect ratio is presented in Table 2.
The strain in the SMA wires (eSMA) is a function of the shear
strain amplitude, c, and the aspect ratio, R. When the shear strain
increases from 50% to 200%, the strain generated in SMA wires increases.
The SMA strain also goes up by enhancing the aspect ratio
of the base isolator. Fig. 2a shows the variation of SMA wire strain
by increasing the shear strain amplitude and the aspect ratio of the
rubber bearing. At 200% shear strain amplitude, the SMA wires in
all of the base isolators experience a strain greater than 10%. It
can be also observed that the strain induced in SMA wires will
not exceed 10% when the base isolator is subjected to shear strains
lower than 100%. However, at larger shear strains, the SMA wire in
the base isolator with high aspect ratio can experience as high as
27% strain.