7RigidFrameStructures
Arigidframehighrisestructuretypicallycomprisesparallelororthogo
allyarra
gedbe
tsco
sisti
gofcolum
sa
dgirderswithmome
tresista
tjoi
tsResista
cetohorizo
talloadi
gisprovidedbythebe
di
gresista
ceofthecolum
sgirdersa
djoi
tsTheco
ti
uityoftheframealsoco
tributestoresisti
ggravityloadi
gbyreduci
gthemome
tsi
thegirders
Theadva
tagesofarigidframearethesimplicitya
dco
ve
ie
ceofitsrecta
gularformItsu
obstructedarra
geme
tclearofbraci
gmembersa
dstructuralwallsallowsfreedomi
ter
allyforthelayouta
dexter
allyforthefe
estratio
Rigidframesareco
sideredeco
omicalforbuildi
gsofuptoabout25storiesabovewhichtheirdriftresista
ceiscostlytoco
trolIfhoweverarigidframeiscombi
edwithshearwallsorcorestheresulti
gstructureisverymuchstiffersothatitsheightpote
tialmayexte
dupto50storiesormoreAflatplatestructureisverysimilartoarigidframebutwithslabsreplaci
gthegirdersAswitharigidframehorizo
tala
dverticalloadi
gsareresistedi
aflatplatestructurebytheflexuralco
ti
uitybetwee
theverticala
dhorizo
talcompo
e
ts
Ashighlyredu
da
tstructuresrigidframesaredesig
edi
itiallyo
thebasisofapproximatea
alysesafterwhichmorerigorousa
alysesa
dchecksca
bemadeTheproceduremaytypicallyi
cludethefollowi
gstages
1Estimatio
ofgravityloadforcesi
girdersa
dcolum
sbyapproximatemethod2Prelimi
aryestimateofmembersizesbasedo
gravityloadforceswitharbitraryi
creasei
sizestoallowforhorizo
talloadi
g3Approximateallocatio
ofhorizo
talloadi
gtobe
tsa
dprelimi
arya
alysisofmember
forcesi
be
ts4Checko
drifta
dadjustme
tofmembersizesif
ecessary5Checko
stre
gthofmembersforworstcombi
atio
ofgravitya
dhorizo
talloadi
ga
d
adjustme
tofmembersizesif
ecessary6Computera
alysisoftotalstructureformoreaccuratechecko
memberstre
gthsa
ddrift
withfurtheradjustme
tofsizeswhererequiredThisstagemayi
cludetheseco
dorderPDeltaeffectsofgravityloadi
go
thememberforcesa
ddrift7Detaileddesig
ofmembersa
dco
ectio
s
fThischapterco
sidersmethodsofa
alysisforthedeflectio
sa
dforcesforbothgravitya
dhorizo
talloadi
gThemethodsarei
cludedi
roughlytheorderofthedesig
procedurewithapproximatemethodsi
itiallya
dcomputertech
iqueslaterStabilitya
alysesofrigidframesarediscussedi
Chapter16
71RIGIDFRAMEBEHAVIOR
Thehorizo
talstiff
essofarigidframeisgover
edmai
lybythebe
di
gresista
ceofthegirdersthecolum
sa
dtheirco
ectio
sa
di
atallframebytheaxialrigidityofthecolum
sTheaccumulatedhorizo
talshearabovea
ystoryofarigidframeisresistedbysheari
thecolum
softhatstoryFig71Theshearcausesthestoryheightcolum
stobe
di
r