Dynamic properties of soils including small-strain and strain-dependent shear modulus and damping are influenced by the degree of saturation and inter-particle suction forces. This change can affect the overall dynamic response of geotechnical systems under earthquake motion. Thus, strain-dependent dynamic material properties including shear modulus and damping play major roles in the seismic response. To this end, accurate estimation of these parameters in various saturation conditions is valuable. This paper focuses on adapting a cyclic triaxial system for dynamic tests with controlled degree of saturation (suction) using axis translation technique. The system development and testing procedure, the preliminary results of suction-controlled, drained cyclic triaxial tests on a fine, uniformly graded sand, and how the changes of suction affect the dynamic properties are presented in this paper. The challenges include controlling and measuring the suction in fast loading during a drained cyclic test and calculating the shear strain and modulus from axial stress-strain hysteresis loops during cyclic triaxial tests. The preliminary data presented in this paper clearly indicates the effect of suction on the shear modulus at a medium strain level.
