In the past, the damping of soils at small strains in the range
'Yc ... 0.0001-0.01% has been studied mainly with high frequency
resonant column tests (Woods 1991, 1994), while the
low frequency cyclic shear tests, such as cyclic triaxial, cyclic
torsional shear, and cyclic simple shear, have been used primarily
to measure A at larger 'Ye. More recently, however, technical
improvements in small-strain cyclic testing with triaxial,
torsional, and simple shear devices have resulted in reliable
measurements of A at very small 'Ye. Some examples of such
complex and often innovative small-strain laboratory experiments
are presented in Goto et al. (1991), Kim and Stokoe
(1994), Hayashi et al. (1994), Soga (1994), Tatsuoka et al.
(1994), and Shibuya et al. (1995).