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Acknowledgements
• Based Heail! on"
• #$e %ost Common Errors in Seismic
&esign'And How to Properl! Aoid
#$em• (CSEA )*+ Annual Con-erence
Proceedings
•B! #$omas . Heausler, PE, SE•Structural Engineer
•/ansas Cit!, %0
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Pre-ace
• 1isting o- common errors was
deeloped b! #om Heausler and Bob
Paullus during reiew o- ot$er
engineers2 work• Based 0n E3perience
• S$ould not be misconstrued as a
consensus document o- t$e ASCE 4Seismic Subcommittee
• %a! be used as a c$ecklist -or &esign
or Reiew
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Standards Coered
• ASCE 7-10
• IBC 2012
• AISC 360-10
• ASIC 341-10
• ACI 318-11 (including Chapter 21 and
Appendix !• "ther Standard#
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aorite #op #en Errors
• (o. +*" (eglecting Additional Re5uirements
-or C$ords, Collectors, 6 &iap$ragms
• (o. 7" 8mproper &istribution Base S$ear oer
Heig$t
• (o. 9" ailure to multipl! E b! *.4 -or AS&
design
• (o. 4" (eglect o- combining ort$ogonal
E--ects
• (o. :" R;
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aorite #op #en Errors
• (o. =" %odal Response Spectrum Anal!sis will
Capture All 8rregularities and be Conseratie
• (o. " (eglecting " (o or 8nade5uate Redundanc! in
S!stem
• (o. )" (o Continuous 1oad Pat$
• (o. +" ?8 &idn2t know 2all Had Eart$5uakes
Around Here
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Seismic &esign Categor! S&CD A
• ASCE 4;+* Section ++..+ ; %apped
Acceleration Parameters
• ASCE 4;+* Section ++.: ; SE8S%8C &ES8(
CA#E0R• ASCE 4;+* Section ++.4 ; &ES8(
REFG8RE%E(#S 0R SE8S%8C &ES8(
CA#E0R A
− Send to Section +. ; eneral Structural 8ntegrit!− reeboard Re5uirements -or RC 8< #anks"
Section +=.4.:.+.)
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Seismic &esign Categor! S&CD A
• ASCE 4;+* Section +. ; eneral Structural
8ntegrit!
− S$ould (ot Gse An! 0- #$e Proisions 0- C$apter +)
− 8nstead, Gse #$e eneral Structural 8ntegrit!
Proisions 0- Section +.
− eneral Structural 8ntegrit! Proisions Hae Some 1oads $ic$
%a! 0-ten Be Erroneousl! Gnaccounted or"
• #$e -orces re5uired include +I dead load, =I o- dead plus
lie load -or beam connections, and )*I o- wall weig$t -or
wall connections
• (on;Structural Components in Seismic &esign Categor! A
are e3empt -rom Seismic &esign re5uirements, as stated in
Section ++.4
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8mportance actor
• ASCE 7-10 Secti$n 11%&%1'a)le 1%&-2'
a)le 1%&-1
• IBC 2012 a)le 1604%&
− I*p$rtance +act$r I# Ba#ed ,p$n i#.
Categ$r/ And he A##$ciated ie Saet/'
aard And E##ential ature " he
Structure
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8mportance actor
• Chec. )$th ASCE 7 and IBC a)le#− A t/pical )uilding can #$*eti*e# e5$l5e int$
an Ie eual t$ 1%2& $r 1%& hen $ccupanc/ $r
u#e expand#%− Exa*ple#
• e5en relati5el/ #*all churche# ($ccupanc/
greater than 300!
• a )uilding here haard$u# *aterial# are #t$red
− +$r Building e#ign Ie 9 1%0' 1%2&' 1%&0
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8mportance actor
• $n-Structural C$*p$nent#− Ip 9 1%0' $r 1%& $nl/ ASCE 7-10 Secti$n 13%1%3
− Ip *a/ n$t eual Ie' and in #$*e in#tance# Ip
*a/ )e le## than Ie%
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Continuous 1oad Pat$
• ASCE 4;+* Section +).+.>
−
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Continuous 1oad Pat$
• ASCE 4;+* Section +).+.>
− 8n Addition #o #$e Speci-ics, #$e
Engineer 8s Re5uired #o Proide A
Continuous 1oad Pat$ or All 8nertialorces
− rom #$eir 0rigin #o #$e oundation
− Suc$ 1oad Pat$ S$all Con-orm #o #$e
Relatie Sti--ness And Strengt$ 0- #$eElements $ic$ E3ist 8n #$e Structure
• &e-ormational Compatibilit!
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Response %odi-ication actor" R
• ASCE 4;+* #able +).);+ and +=.;+, )
− #$e Response %odi-ication Coe--icient, R, 8s
Part 0- A Concept $ere An Elastic &esign
%a! Be Per-ormed− But it$ &ue Consideration 0- #$e
0erstrengt$ And &uctilit! 8n$erent 8n #$e
1ateral orce Resisting S!stem.
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Response %odi-ication actor" R
• #o Assure Reliabilit! 8n #$e 0erstrengt$
And &uctilit!, %an! Re5uirements Are
#riggered it$ Eac$ R actor •
?R #ables 1ist #$e &etailing Re5uirements#riggered
• #$e ?Strings Attac$ed #o A8SC R> Structures
And AC8 C$apter )+ Structures Can Be E3tremel!
Signi-icant
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0erstrengt$ actor" K*
• ASCE 4;+* #able +).);+
− Also in ASCE 4;+* #ables +=.;+, and +=.;)
• $en &iap$ragms Are le3ible
− Allowed #o Reduce K* actor B! *.=
− #$is Proision 8s 1isted 8n Small Print As
ootnote g And 8s 0-ten 0erlooked
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%odal Response Spectrum
Anal!sis #riggers
• ASCE 4;+* Section +).>
− #able +).>;+ ; HoriLontal 8rregularities
− #able +).>;) ;
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%odal Response Spectrum
Anal!sis #riggers
• ASCE 4;+* Section +).> #able +).>;+
and #able +).>;)• #ables Re5uire Close Reiew #o 8nterpret #$e
#riggers.• #$e ASCE &esign uide Seismic 1oads" uide
#o #$e Seismic Proisions 0- ASCE 4;+* B!
inle! C$arne! Has A 1isting 0- #$e #riggers
8n A %ore Gser riendl! ormat
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0erstrengt$ actor, K*, #riggers
− ASCE 4;+* Section +). ; 1oad
Combinations wit$ K*
− ASCE 4;+* Section +).).=.) ; Cantileer
Columns
− ASCE 4;+* Section +).+*.).+ ; Collectors M
1ig$t rame, ood E3cepted
− ASCE 4;+* Section +).>.>.> ; Columns,
Beams Supporting &iscontinuous alls− ASCE 4;+* Section +).+>.:.= Pile Anc$orage
− A8SC w$ere R>
− AC8 C$apter )+, Appendi3 &, etc.
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0erstrengt$ actor, K*, #riggers
• K* 8s An Ampli-ication #o #$e orces
− or E3ample"
• 8n a steel braced -rame s!stem, in order -or t$e
diagonal brace to !ield and dissipate energ! in acontrolled and reliable manner, all ot$er portions
o- t$e load pat$ E.. Connections, bolts, welds,
gusset plates, anc$or bolts, columns and
collectorsD need to be stronger t$an t$e ma3imum
anticipated strengt$, or -orce, in t$e brace.#$ere-ore, omega Lero ampli-ication and load
combinations are speci-icall! triggered in t$e
sections mentioned aboe and in material
standards suc$ as A8SC and AC8.
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Redundanc! M R$o ND
• R$o 8s A actor #$at PenaliLes
Structures #$at &o (ot Hae
Redundanc!
• ASCE 4;+* Section +).>.− R$o O +.* or +.>
− R$o O +.* -or" S&C B, C, -or &ri-t
Calculations, p (on;structuralComponentsD orces, Collectors, K* 1oad
Combinations, and &iap$ragms
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1oad Combinations and
Allowable Stress &esign M *.4 E
• or Allowable Stress &esign AS&D 1oad
Combinations
• ASCE 4;+* Section +)..).>
• Section +)..) s$all be used in lieu o-
Sections ).>.) and )..+
− Eart$5uake orces Are At Strengt$ 1eel
So or #$e AS& Combinations, Gse *.4 Eor 1R& Gse +.* ED
− #$e *.4 E Applies #o p (on;structural
Component orcesD Also
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0rt$ogonal E--ects
• Eart$5uake orces S$all Be Calculated
or Eac$ 0- #$e #wo Primar!
0rt$ogonal &irections
− #o Consider #$e E--ects 0- Eart$5uakeorces At Some Angle 0t$er #$an #$ose
#wo &irections, ?0rt$ogonal E--ects %ust
Be Considered
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0rt$ogonal E--ects
• ASCE 4;+* Section +).=
− Re5uires #$at 8rregular Buildings 8n S&C C,
And Corner Columns 8n S&C &,E, Be
Considered it$ +**I 0- orces 8n 0ne&irections And >*I 8n 0t$er
− 8t S$ould Be (oted #$at 8EEE :7>
Electrical E5uipmentD Applies 0rt$ogonal
E--ects #o All Conditions, 8ncluding CornerAnc$or Bolts
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E--ectie Seismic eig$t
• ASCE 4;+* Section +).4.) de-ines t$e
E--ectie Seismic eig$t, .
− E3cept as mentioned below, lie load is not
included in t$e inertial -orce, $oweer t$eseismic -orce is later combined wit$ dead
and lie loads in t$e load combinations
• ASCE 4;+* Section +).4.) stipulates t$at
s$all include t$e -ollowing masses")=I o- Storage lie load, Partitions +*
ps-
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E--ectie Seismic eig$t
• ASCE 4;+* Section .>.)
− 8ndustrial 0perating eig$t M and
unbalanced conditionsD, )*I o- snow
>*ps-, and Roo- ardens.
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Period #
• ASCE 4;+* Section +).9.).+ $as comple3
met$ods and limits on calculating t$e
Period #.
− 8t 8s Acceptable #o Gse # O #a, orSimplicit!
− Appro3imate ormulas S$all (ot Be Gsed
or (on;building 8ndustrialD Structures,
ASCE 4;+* Section +=..
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&istribute Base S$ear oer Heig$t
• ASCE 4;+* Section +).9.>
− 0nce #$e Base S$ear,
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&istribute Base S$ear oer Heig$t
• ASCE 4;+* Section +).9.>
− 0nce #$e Base S$ear, 0- #$e Heig$t Aboe #$e Base, (ot
+) Heig$t 0r Center 0- rait!
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&istribute Base S$ear 0er
Heig$t ormula
• ASCE 4;+* Section +).9.>
− E5. +).9;+)D 3 O C3 <
− C3 O w3 $3k Sum wi $ik
− Spreads$eets are o-ten used to calculatet$e -orces at eac$ -loor leel
− A common mistake is to $ae errors wit$in
t$e spreads$eet logic andor calculate C3and t$en multipl! it b! total eig$tD orw3 weig$t at eac$ -loor. C3 s$ould be
multiplied b! t$e Base S$ear
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%odal Response Spectrum
Anal!sis
• ASCE 4;+* Section +).7
− #$e purpose o- a %odal Response
Spectrum Anal!sis is (0# to re-ine t$e
magnitude o- t$e Base S$ear − Purpose 8S to more accuratel! per-orm t$e
-ollowing"
• &istributes Base S$ear 0er Heig$t
• HoriLontal #orsional E--ects• Hig$er %ode E--ects
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%odal Anal!sis
• ASCE 4;+* Section +).7..+
− Scaling 0- #$e Results 0- %odal Response
Spectrum Anal!sis 8s Re5uired And
Allowed.− Especiall! or Buildings, #$e Results 0-
#$e Response Spectrum S$ould Be
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%odal Anal!sis
• ASCE 4;+* Section +).7..+" Results
must be scaled to wit$in 9=I o- <
calculated b! E1 %et$od
− 8t is o-ten wise to c$eck !our so-twareresults wit$ a small regular structural
model w$ere results are predictable wit$
$and calculations
• Con-idence is gained to use t$e so-tware on alarge comple3 structural models.
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Accidental #orsion
• ASCE 4;+* Section +).9..)
− Accidental #orsion %ust Be Applied
− 8n Addition #o 8n$erent #orsion
− Re5uired #$is 8s #o Preent eak#orsional Resisting Arrangements As ell
As Account or Gne3pected &istribution 0-
1ie 1oad And Gne3pected Sti--ness 0-
Structural And (on;structural Elements− Proision Applies #o (on;building
Structures As ell As Buildings
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Accidental #orsion
• ASCE 4;+* Section +).9..)
− or #orsionall! 8rregular Buildings,
Ampli-ication 0- #$e Accidental #orsion
%a! Be Re5uired− ASCE 4;+* Section +).9..>
• See igure +).9;+ #orsional Ampli-ication
actor, A3
•
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Accidental #orsion
• ASCE 4;+* Section +).9..)
− ASCE 4;+* Section +).9..>
• $en C$ecking -or #!pe +a or +b #orsional
8rregularit!
− Gse #able +).+);+ to &etermine Ta
• #$e ollowing Recommendation 8s (ot
Currentl! in ASCE 4
− Recommendation rom Presenter, 0nl!
− 8 #$e Stor! &ri-ts At All 1ocations 0n A1eel Are 1ess #$an *.+=Ta to *.)*Ta, &o (ot
Consider A #orsional 8rregularit!
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Accidental #orsion
• E3ample" #orsion w
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&ri-t C$eck
• ASCE 4;+* Section +).+)
− Section +).9.: &ri-t &etermination
• ASCE 4;+* #able +).+);+ ; Allowable
&ri-t 1imits− Results -rom t$e elastic anal!sis must be
ampli-ied b! Cd to render actual e3pected
de-lections.
− Cd is a er! large alue, t!picall! a -actor o-
about > to =
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&ri-t C$eck
• ASCE 4;+* #able +).+);+ ; Allowable
&ri-t 1imits
− #$e dri-t is t$en diided b! 8e, because t$e
allowable dri-ts are organiLed into a tablew$ic$ considers Risk Categor!
− Be care-ul w$en using Allowable Stress
&esign load combinations
− &0 (0# appl! t$e *.4E to dri-t calculations
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&iap$ragm orces
• ASCE 4;+* Section +).+*.+.+
− orces At 1ower loor &iap$ragms %a! Be
Hig$er #$an #$ose Gsed or #$e 1ateral
orce Resisting S!stem− &ue to &iap$ragms #rans-erring 1oads
-rom 0ne
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&iap$ragm orces
• ASCE 4;+* Section E5 +).9;+)D 3OC3<
− #$is 8s &ue #o Hig$er %ode E--ects 8.E.
%odes Hig$er #$an #$e irst %odeD $ere
#$e 1ower loors %a! Be AcceleratingHig$er #$an Calculated 8n E5 +).9;+)D
− #$e &iap$ragm orce E5uation ASCE 4;+*
Section E5 +).+*;+D 8s Similar #o E5 +).9;
+)D, Howeer p3 %inimums 0- E5 +).+*;)D0-ten oern or #$e 1ower loors
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p (on;structural Components
C$apter +>
• ASCE 4;+* E5 +>.>.+D
− (on;structural components ma! also
e3perience $ig$er local accelerations due
to $ig$er mode e--ects as well asampli-ication o- t$e -orce wit$in t$e non;
structural element itsel-
− 8ndustrial structures o-ten -eature er!
large p -orces
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p (on;structural Components
C$apter +>
• ASCE 4;+* E5 +>.>.+D
− 8t 8s Gnlikel! #$at #$e p orces 0n #wo
&i--erent loors ould 0ccur At #$e Same
Point 8n #ime− 0ne %et$od 0- Accounting or #$e p
orces 8n A Computer %odel 8s #o Run #wo
Conditions
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p (on;structural Components
C$apter +>
− #o Run #wo Conditions"
• Run < 1oad Combinations it$ #$e eig$t 0-
#$e E5uipment 8ncluded 8n #$e Seismic eig$t
0- #$e loor And Base S$ear &istributed 0er
#$e Heig$t Per E5 +).9;+)D• Run p 0n Piece 0- E5uipment 0nl! #o
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p (on;structural Components
C$apter +>
• ASCE 4;+* Section +=.> ; (on;Building
Structures Supported B! 0t$er
Structures
− $en t$e eig$t o- t$e Supported (on;Building Structure is 1ess t$an )=I o- t$e
#otal Structure %ass
• Gse C$apter +>
− $en (on;structural Components et .)
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1arge p (on;structural
Components C$apter +=
− $en (on;structural Components E3ceed
)=I 0- #otal Structure %ass
• or #$ese Hea! Components, A Computer
%odel Capturing #$e Sti--ness And &esign
Coe--icients 0- Bot$ #$e Component And #$ePrimar! Structure %ust Be Considered #oget$er
− %ust Appl! E #o p Combinations
− R$o Redundanc!D O +.*
− K*
&oes (ot Appl! #o p
1oad Combinations
• E3cept, K* &oes Appl! 8n AC8 Appendi3 &
Calculations
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all &esign
• all Panels %ade 0- Concrete And
Concrete %asonr!, C%G Hae
Per-ormed Poorl! 8n Past Eart$5uakes
• ASCE 4;+* Section +).++.+ ; allPanels
• ASCE 4;+* Section +).++.).+ ; all
Connections S$ould Be 8mplemented,As ell As AC8 Appendi3 & or
Anc$orage
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oundation #ies
• AC8 >+9;++ C$apter )+"
− #o Assure #$at #$e oundation S!stem
Acts As An 8ntegral Gnit
− Preents 0ne Column 0r all rom %oingAppreciabl! wit$ Respect to Anot$er
− Applies #o Pile Caps 8n S&C C, As ell As
&,E,, and Spread ootings -or S&C E and
− Can Possibl! Be 8ntegral it$ Slab or1ig$tl! 1oad Buildings Engineered %etal
BuildingsD
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Reduction o- oundation
0erturning
• ASCE 4;+* Section +).+>.
− Allows -or a reduction o- t$e bearing
pressures at t$e Soil;oundation 8nter-ace
− orces ma! be reduced b! )=I inrecognition t$at t$e -irst mode triangular
-orce distribution will likel! not occur
wit$out $ig$er mode e--ects occurring and
negating t$e direction o- t$e -irst mode• Results in reduced oerall oerturning moments
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8BC )*+) 0errides
− ASCE 4 is on a si3 !ear update c!cle and
8BC is on a t$ree !ear
− Also tec$nical c$anges to 8BC o-ten $ae
to be approed well be-ore t$e issue date• 8neitabl!, Coordination Between #$e #wo
Su--ers
• %aterial Standards 8ssues %ust Be Coordinated,
0-ten #$roug$ Errata, Supplements 0r 8BC
Publis$ed Amendments. 8t 8s Essential #oPeriodicall! C$eck or #$ese C$anges
• See Standards Suc$ As" A8SC, AC8, A8S8, AC,
Etc.
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ASCE 4;+* #H8R& PR8(#8(
− 8t 8s Recommended #$at #$e Gser %ake
Gse 0- #$e ASCE 4 E3panded Seismic
Commentar!
−
+>= Pages 0-
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ASCE 4;+* #H8R& PR8(#8(
− or #$ose #$at 0wn A irst And Second
Printing, ou %a! &ownload A U .pd-D ile
0- #$e Commentar! or ree rom #$e
ASCE ebsite
− #$is Commentar! as &eeloped B! #$e
(EHRPBSSC Proisions Gpdate
Committee and &escribes #$e Reasons or
#$e 8ndiidual Proisions 0- #$e ASCE 4
Standard
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Re-erences
• ASCE 4;+*, %inimum &esign 1oads -or
Buildings and 0t$er Structures, #$ird
Printing, American Societ! o- Ciil
Engineers, Reston,
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Re-erences
• AC8 >+9;)*++, American Concrete
Association, armington Hills, %8 9>>+
• ASCE C$arne! P$.&., P.E., inle! A."Seismic 1oads" uide to t$e Seismic
Proisions o- ASCE 4;+*, American
Societ! o- Ciil Engineers, Reston,
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