TY JOUR TI ANALYSIS OF THE INFLUENCE OF SUBGRADE STIFFNESS ON THE FREQUENCIES AND MODE SHAPES OF STRUCTURES KW soil bases stiffness KW deformation modulus of the soil bases stiffness KW dynamic characteristics KW frequencies KW mode shapes KW modal masses KW symmetry KW optimal stiffness of the structure. JO Construction and Architecture AU Strok, S.I. AU Strok, S.A. AU Drozdov, V.V. PY 2018 IS 6 PB Publishing Center RIOR