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Unformatted text preview: elow. For the simplicity, we assume the foundation is vibrating
under the following assumptions:
(1) The foundation is rigid and vibrating in the lateral
direction without rotation.
(2) An earthquake disturbance is due to SH type incident
earthquake wave propagating upward. (3) Soil springs attaching the foundation to the free field
soil are KS and Kb at the representative points. An equation of the motion for the foundation model is
m : mass of foundation Ks, Kb : soil springs
Uf : lateral displacement of foundation us, ub : lateral displacement of free field soil
Eq.(1) can be rewritten into:
(2) Putting: K = K S + Kb Eq.(2) : (3)
(2) can be rearranged as:
Eq.(4) can be rewritten as:
(6) Expressing uf by:
u f = x + ue (7) and substituting Eq.(7) into Eq.(6):
then, Eq.(8) can be obtained. (8) (8)
Eq.(8) equals a...
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- Summer '14