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From OWEN F Hughes Book, Chapter Two, Page 2-1.

FREQUENCY DOMAIN:

If the fore-!"sp#aeme$t re#at"o$ "s #"$ear or o$#% s#"ght#% $o$#"$ear, the$ theproem of a#u#at"$g #oa! e'ets a$ &e so#(e! )"$ the F*E+ENC O/0IN,

w"th freue$% as the pr"$"pa# "$!epe$!e$t (ar"ae "$stea! of t"me, wh"h

great#% s"mp#"3es the a#u#at"o$s.

The freue$% 4&ase! !"str"&ut"o$ of a #oa! or a #oa! e'et 5respo$se6 "s a##e! a

spectrum, a$! so we speak of a wave spectrum a$! a response spectrum.

TIME DOMAIN:

If the fore-!"sp#aeme$t re#at"o$ "s $o$#"$ear, the$ the proem must &e so#(e!

"$ the )TI/E O/0IN, w"th t"me as the "$!epe$!e$t (ar"ae.

QUASI-STATIC ANALYSIS

0 uas"-stat" a$a#%s"s "s s"mp#% a stat" a$a#%s"s "$ wh"h the mot"o$s are

est"mate! a$! the"r e'et o$ the struture "s aou$te! for appro7"mate#% &%

"$#u!"$g some INERTIA FORCES.

8#ow#% (ar%"$g #oa!s are those for wh"h e(e$ the shortest ompo$e$t per"o! "s

appre"a% #o$ger tha$ the fu$!ame$ta# 5#o$gest6 $atura# per"o! of ("&rat"o$ of

the struture. I$ most ases, s#ow#% (ar%"$g #oa!s a$ &e !ea#t w"th &% mea$s of

stat" a$a#%s"s w"th o$#% a sma## #oss of aura%, whereas rap"!#% (ar%"$g #oa!s

usua##% reu"re a !%$am" a$a#%s"s for su9"e$t aura%.

Whe$e(er poss"e, to m"$"m":e omputat"o$ t"me, stat" a$! !%$am" a$a#%ses

are performe! separate#%, w"th the #atter !ea#"$g o$#% w"th the ;utuat"o$ "$

#oa!, that "s, the !eparture from the stat" #oa!. Tota# respo$se of the struture "s

the$ o&ta"$e! &% super"mpos"$g the two resu#ts.