The paper defines a full model of the fluid dynamics that characterize
hydraulic semiactive vibration absorbers (SAVAs) developed for struct
ure application. A flow model is established that indicates that SAVAs
are able to both store and dissipate energy. The work demonstrates th
at the effect of compressibility (at the piston and at the valve) and
the variation of bulk modulus with pressure can be important to the de
sign and implementation of an SAVA system for civil structures. The pa
per also describes laboratory procedures used to identify model parame
ters. The paper then describes the performance of the SAVA when used t
o provide vibration mitigation for a laboratory test structure. The ex
pected results based on the model and experimental results are compare
d. The work indicates that SAVA technology provides a robust, reliable
, and inexpensive means of achieving structural control.