4 - Memorial University of Newfoundland DAI

the prolotype. Damping is dcfincd by the damping ratio:
where
(=E
C. '
C = the structural damping mnslant, and
C. =the structural critical damping constant.
'I'IIc condition (, = (, ahould be at leaat appmximslely aatiafied.
4.6 Model Design and Fabrication
Tl~c redotcod rn~del, fabricated to observe the dynamic behavior in air and
in walcr, war designed to bo hydm-elastically similar to the main atruc-
turnl systcm of n 1ypiea.l full-scale four-logged tower prototype. Por practical
rcnsons, an cxact reduced scale rcplica of the prototype was "not pouible.
Novcrtholess, tho modelled towor war designed to have the followin8 salient
fenltlrr*.
4.6.1 Description of the Prototype
The prototype strucluw is n 73 m tall eon~entionolsteel jacket platform (i.e.,
n combir~nlion of k-bracing and diagonal bracing) operating in 50 m of wa-
ter, and llns overall structural external dimensions depicted in Figure4.1-4.2.
A 3-0 viow simulationis shown in Figure 4.3. Tables 4.2 and 4.3 depict the
mc~nbersections and material properties. (Thegeometricalconfiguration and
rnen~ber amtion properties ol the structure wen obtained from Ref. [61,62].)
Is table 4.3, m&id refers to the material and smt~en properties of a mod-
ified version of tlre prototype. This modification in certain member section
properties rns carried out to simplify the design of the reduced model, and