dynamics 2006 structural seismic design manual 1

Volumes II and III will provide a series of structural/seismic design examples for buildingsillustrat ingthe seismic design of key parts of common building types such as alarge three-sto

COD APPLICATUO EXAMP LES

'] ']

1 1 '] '1 :I , ) : )

rI ,I ,1

I 1 I I I I I

Table of Con tents

Example I Earthquake Load Combinations:

Example 4 Vertical Irregularity Type laand Type Ib § 12.3.2.2 42

Example 10 Horizontal IrregularityType Ia and Type Ib . §12.3.2.1 59

2006 IBC Stru ctural/S eismic Design Manual, Vol I iii

EXAMPLE DESCRIPTION ASCE/SEI7-05 PAGE

i v 2006IBC Structural/Seismic Design Manual, Vol I

Simplified Alternative Structural Design Procedure §I2.14 8

Combination of Framin gSystems:

Combinationof StructuralSystems :

Elements Supporting DiscontinuousWalls orFrames §12.3.3.3 I 10

Out-of-Plane Seismic Forcesfor Two-StoryWall Panel §12.11.I

Deformation Compatibility for SeismicDesign

ExteriorNonstructural Wall Elements: Precast Panel §13.5.3 153

Out-of-Plane WallAnchorage of Concreteor Masonry §12.11.2

Determination of Diaphragm ForceFpx :

2 006 I B C S tructural/Seismic D esign Man ual, V ol V

vi 2006IBC Structural/Seismic Design Manual, Vol

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The examples in the 2006lBC Structural /Seismic Design Manual do not necessarily illustratethe only appropriate methods of design and analysis Proper engineeringjudgment shouldalways be exercised when applying these examples to real projects The 20061BC Structural /Seismic Design Manual is not meant to establish a minimum standard of care but;

instead, presents reasonable approaches to solving problems typically encountered instructural/seismicdesign

The example problem numbers used in the prior Seismic DesignManual - 2000 IECVolume I code application problems have been retained herein to provide easy reference tocompare revised code requirements

SEAOC, NCSEA and ICC intend to update the 2006 lBC Structural /Seismic Design Manual

with each edition of the building code

Jon P Kiland and Rafael SabelliProject Managers

2006 IBC Structural/Seismic Design Manual, Vol I vii

viii 2006 IBC Structural/Seismic Design Manual, Vol I

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The 2006 IBC Stru ctural /S eismic D esign M anual V olume Jwaswritten by a group of highlyqualified structural engineers They were selected by a steering committee set up by theSEAOC Board of Directors and were chosen for their knowledge and experience with

structural engineering practice and seismic design The consultants for Volumes I, II,and IIIare:

Jon P.Kiland, Co-Project M anage r

Rafael Sabelli,Co-Project Manager

Douglas S.Thompson

Dan Werdowatz

Matt Eatherton

John W LawsonJoe MaffeiKevin MooreStephen Kerr

Anumber of SEAOC members and other structuralengineers helped checktheexamples inthis volume Duringits development, drafts of the examples were sent to these individuals.Their help was sought in review of code interpretations as well as'detailed checking of thenumerical computations

I _.

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Close collaboration with the SEAOC Seismology Committee was maintained during

the developmentof the document The 2004-2005and 2005-2006 committees reviewedthe document and provided many helpful comments and suggestions Their assistance isgratefully acknowledged

ICC

2006 IBC Structural/Seismic Design Manual, Vol I ix

Sugg es tion s for Impro vem ent

Inkeeping withSEAOC's andNCSEA's MissionStatemen ts: "to advancethe structural

engineeringprofession" and "to provide structura lengineers withthe mostcurrent

informa tion and tools to improvetheir practice," SEAOC andNCSEA plan toupdatethis

docum ent as structural/seismicrequirements change and new research and better

understanding of buildingperforma nce in earthqu akesbecomes available

Comm ents andsuggestionsfor improvementsarewelcome and shou ldbe sentto

thefollowing:

Structural Engineers Association ofCalifornia (SEAOC)

Attention : Executive Director

1 14K Street,Suite 260Sacramento, California 95814

Telephone: (916)447-1198;Fax: (916) 932-2209

E-ma il: eeiWseaoc.org;Web address: www.seaoc org

I I I I I

x

SEAOCand NCSEA have madea substantialeffort to"e sure that theinformationinthis

document is accurate.Inthe event that corrections orclarifications areneeded,these will b

posted on the SEAOC we site at h/lP: //11 111 ' seaoc o rgor on the ICCwebsiteat

http: / w ll 1l .iccsaf e org SEAOC ati tssole discretion,mayormay not issue written

errata

2006 IBC S tructural/Seismic DesIgn M anual, Vol I

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Volume I of the 2006lBC Structural /Seismic D esign Manual : C ode A pp lication Exampl es

deals withinterpretation and use of the structural/seismic provisions of the 2006

l ntem ational Building C ode'"(!BC) The 2006lBC Structural /Seismic D esign Manual isintended to help the reader understandand correctly usethemc structural/seismicprovisionsand to provide clear, concise, and graphic guidance on the application of specific provisions

of the code It primarily addressesthe major structural/seismic provisions of the !BC, with

interpretation of specific provisions and examples highlighting their proper application

The 2006 !BC has had structural provisions removed from its text and has referenced several

national standards documents for structural design provisions The primary referenceddocument is ASCE/SEI 7-05, which contains the "Minimum Design Loads for Buildings andOther Structures." ASCE/SEI 7-05 is referenced for load and deformation design demands onstructural elements, National Material design standards (such as ACI,AISC, MSJC andNOS) are then referenced to take the structural load demands from ASCE/SEI 7-05 andperform specific materialdesigns

Volume I presents 58 examples that illustrate the application of specific structural/seismicprovisions of the !Be Each example is a separate problem, or group of problems,and dealsprimarily with a single code provision Each example begins with a description of theproblem to be solved and a statement of given information The problem is solved throughthe normal sequence of steps,each of which is illustrated in full.Appropriate code references

for each step are identified in the right-hand margin of the page

Thecomplete 2006lBC Structural /Selsmic De sign M a nualwill have three volumes

Volumes II and III will provide a series of structural/seismic design examples for buildingsillustrat ingthe seismic design of key parts of common building types such as alarge three-story wood frame building,a tilt-upwarehouse, a braced steel frame building,and a concreteshear wall building

While the 2006lBC Stru ctural/Seismic D esign Manual is based on the 2006 !BC, there aresome provision ofSEAOC's 2005Recommend ed Lat eral Forc e Provisions and C ommentary

(Blue Book) that are applicable When differences between the !BC and Blue Book aresignificant they are brought to the attention of the reader

The 2006lBC Structural /Seism ic Design Manual is intended for use by practicing structuralengineers and structuraldesigners, building departments, otherplan reviewagencies,andstructural engineering students

2006 IB C Structural /Seismic Design Manual , Vol I 1

Ho w to U se Thi s Do cum ent

• :JC '>;

The various co eapplicat ionexamplesofVolumeIareorganized by topic consistent with

previous editions.To find an example fora particular provision ofthe code,look at the

upper,outercome r ofeach page,or in the tableof contents

Generally,theASCE/SEI 7-05 notation is used throughout Som eothernotation is defined in

thefollowingpages, orin the examples

Reference to ASCE/SEI7-05 sections and formulas is abbreviated For example,"ASCE/SEI

7-05 §6.4.2" isgiven as§6.4.2 withASCE/SEI 7-05 beingunderstood "Equation (12.8-3)"

is designated (Eq 12.8-3)in the right-hand margins.Similarly,thephrase "T 12.3-1" is

understood to beASCE/SEI 7-05 Table 12.3-1, and"F 22-15" is understood to beFigure

22-15.Throughout thedocument,reference tospecific codeprovisions andequations isgiven in

theright-handmarginunder the category Code Reference

Generally,the examples arepresented in the followingformat.First,there isa statement

of the example to be solved,includinggiven information, diagram s,and sketches This is

followedby the"Calculations and Discussion" section,which provides the solution to the

example and appropriatediscussion to assistthe reader.Finally, many ofthe examples have

a third section designated"Commentary." In thissection,comments and discussion

on the exampleand relatedmaterial are made Commentary is intended to provide abetter

understandingof theexampleand/or to offer guidancetothereader onuse of the information

generated in the example

In general,theVolume Iexamples focusentirely on use of specificprovisions of the code

Nobuilding design is illustrated Building design examples are given in VolumesII and III.

The2006lE e S tructural /S eis mi c Des ign Ma nual isbasedon the 2006 IBC, and the

referenced StandardASCE/SEI 7-05 unless otherwiseindicated.Occasionally, reference is

made to othercodesandstandards (e.g.,2005 AISC Steel ConstructionManual 13thEdition,

ACI 318-05, or 2005 NOS).When this is done,these documentsare clearly identified

2 2006lac Structura l/Seismic Design Manua l, Vol I

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The following notations are used in this document These are generallyconsistent with thoseused in ASCE/SEI 7-05 and other Standards such as ACI and AISC Some new notationshave alsobeen added.The reader is cautionedthat the same notation may be used more thanonce and may carry entirelydifferent meaningsin differentsituations,For example,E can

mean the tabulated elastic modulus under the AISC definition (steel) or it can mean the

earthquake load under§12.4.2 of ASCE/SEI 7-05.When the same notation is used intwo ormore definitions,each definition is prefaced with a brief description in parentheses(e.g.,

steel or loads)before the definition is given

A

area of floor or roofsupported bya membercross-sectionalarea of the base materialarea of anchor, in square inches

the combined effective area, in square feet,ofthe shear walls

in the first story ofthe structure

the story under considerationarea of the load-carrying foundation

the effective area of the projection of an assumed concrete failuresurface upon the surface from whichthe anchor protrudes, in squareinches

area of non-prestressed tension rein forcement

2 006 lac Stru ctural/S eism ic D esign Ma nual , V ol I 3

N ota tion

A s h = total cross-sectional area oftransverse reinforcement (including ]

supplementary crossties)havinga spacings"and crossingasectionwith a coredimensionofh e

As k = area of skinreinforceme nt perunitheightinone sideface

A Slmin = area having minimumamount offlexural reinforcement I

A s , = area of link stiffener

I

AT = tributary area

A v = area of shear reinforcement within a distances,orareaofshear

reinforcementperpendicular to flexuraltensionreinforcement within a

distancesfor deep flexuralmembers

A , ' J = requiredarea oflegreinforcementineachgroupof diagonal bars ina

diagonallyreinforced coupling beam

A vr = area of shear-friction reinforcement

I

A l l' = (web) link web area

A., = the torsionalamplification factor atLevelx - §12.8.4.3

I

a = (concrete) depth of equivalentrectangularstressblock

a = (coandncreteface of sspanupportsdrel)shear span,distance between concentrated load I

a e = cwaoefficientllstrengthdefin ingthe relativecontributionofconcrete strengthto I

a = i§12.8.7ncrementa lfactor relating to theP-delt a ' ef fectsas determined in I

a, = theacceleration at Leveliobtainedfromamodal analysis (§13.3.1) I

a p = amplification factor related.to the response of a system or component

as affected bythetype of seismicattachment determined in§13.3.1

b = (concrete) widthof compressionfaceofmember

b r = flange width

bu = webwidth

4 2006 IBC Structura l /S eism ic D esign Ma nual, Vol

I Notation

b it member width-thickness ratio

C d = deflection amplification factor as given in Tables 12.2-1 or 15.4-1 or

15.4-2

C e = snow exposure factor

em coefficient defined in §Hl ofAISC /ASD, 9thEdition

C, = the seismic responsecoefficient determined in § 12.8.1.1 and §19.3.1

C r = building period coefficient - § 12.8.2.1

C 1'X = vertical distribution factor- §12.8.3

c distance from extreme compression fiber to neutral axis of a flexural

member

D dead load, the effect of dead load

direction parallel to the applied forces

D p = relative seismic displacement that a component must be designed to

d effective depth of section (distance from extreme compression fiber to

db = (anchor bolt) anchor shank diameter

E = (steel) modulusof elasticity

I E combined effect of horizontal and vertical earthquake-induced forces

I Em = (§12.4)seismic load effect including overstrength factors (§§ 12.4.3.2 and

2006 IBC Structural/Seismic Design Manual, Vol I 5

N otation I

s , = modules ofelasticity of concrete ,in psi

I

E. = (concrete)modulusof elasticity of reinforcement

F = load due to fluids

F a = site coefficie nt defined in§11.4.3

F a = axial compressive stressthatwould be permitted if axialforce alone

existed

F b = bending stress that wouldbe permitted if bending momentalone

Iexisted

F aM = nominal strengthofthe base material tobe welded

Fp = seismicforce, induced by the parts beingconnected,centeredat the

component's centerof gravity anddistributed relative to the

Icomponent' smassdistribution, asdetermined in §12.8.3

Fp, = the diaphragmdesignforce

I

F " = specified minimum tensile strength,ksi

F " = through-thicknessweldstresses at the beam-co lumn interface I

Fill = minimum specifiedtensile strengthof the anchor

I

F, = long period site coefficient (at 1.0second period) see§11.4.3

r , = the lateralforce induced at any Leveli- §12.8.3

I

Fw = (steelLRFD)nominalstrength oftheweld electrodematerial

6 20 06 1BC S tructura l/Seis mic D esi gn M anual, Vo / /

notation I

h e = assumed web depth for stability

h ;, h n,h, = height in feetabove the base to Level i ,11orx ,respectively I

h , = heightin feet ofthe roofabove the base

I

hsx = the story height below Levelx

hll' = height ofentire wall or of the segment of wall considered ]

I = the importancefactor determined in accordancewith§11.5.1

I

I = moment of inertia of section resistingexternallyapplied factored loads

I a = moment of inertia of cracked section transformed to concrete

I g = (concrete,neglecting reinforcement) moment ofinertia of gross

concrete section about centroidalaxis

t ; = moment of inertiaof reinforcementabout centroidal axis of member

I

cross section

I = moment ofinertia of structural steel shape,pipe or tubing about

I

centroidal axis of compositemember cross section

I g = (concreteconcrete section about centroidal axis, neglecting reinforcement.,neglecting reinforcement) moment of inertia of gross I

t, = component importance factor that is either 1.00in§13.3.1 or 1.5,as determined I

k = a distribution exponent - §12.8.3

I

L = liveload,except rooflive load, including any permitted live load

reduction (i.e, reduced design live load).Liveload related internal

Imoments or forces Concentrated impact loads

Lo = unreduced design live load

I

L b = (steel) unbraced beam length for determining allowable bending stress

Lp = limiting laterally unbraced length for full plastic flexural strength, I

uniform moment case

L, = roof live load including any permitted live load reduction I

8 20061BC Structural/Seismic Design Manual, Vol I

Not ation

I e (steel RBS) length ofradius cut in beam flangeforreduced beam

1 section(RBS) design

t : length ofacompression member ina frame,measured fromcenter to

centerofthejointsinthe frame

/;, = distance from column centerl ineto centerlineofhinge for reduced

bending strength (RBS) connection design

I " = clear span measuredface-to-face of supports

I " unsupported length ofcompression member

I ll' = length of entire wall,orofsegment of wall considered, in direction of

shear forceLeveli

Leveln =

Level,r =

levelof thestructure referred to bythesubscript i

" i= I"designates the first level above thebasethat level that isuppermost in the mainportion of the structure

that level that isunder design consideration

"x = I" designates the firstlevel above thebase

M = (steel)maximum factored moment

factored momentto be used for design of compressionmembe rI

moment at centerline of column

moment at which flexural cracking occurs in responsetoexternally

applied loads

limiting laterally unbraced length forfull plastic flexuralstrength,

uniform moment casemoment atface ofcolumn(concrete)modified moment

(steel)maximum moment thatcan beresistedb themember intheabsence ofaxial load

(steel) nominal moment strength at section(concrete) required plasticmomentstrengthof shearheadcross section

2006 IBC Stru ctural /Se ismic Des ign M anual, Vol J 9

u , = (steel) nominal plastic flexural strength,FyZ

M p = nominal plastic flexural strength modified by axial load

1

u ; = nominal plastic flexural strength using expected yield strength of steel

M p r = (concrete) probable moment strength determined using a tensile I

strength in the longitudinal bars of at least 1.25;;.and a strengthreduction factorcjJ of 1.0

M, a = accidental torsional moment

M" = (concrete) factored moment at section

I

M" = (steel) required flexural strength on a member or joint

M, • = an elastic stress distributionmoment corresponding to onset of yielding at the extreme fiber from I

M I = smaller factored end moment on a compression member, positive ifmember is bent in single curvature, negative if bent in double I

P = (steel) factored axial load

PDL,i» , r ; = unfactored axial load in frame member

I

P b = nominal axial load strength at balanced strain conditions

r , = (concrete) critical load

10 2006 IB C S tructural/S eismic Design Manual, Vol

Pc = (concrete anchorage) design tensile strength

P" = nominal axial load strength at given eccentricity, or nominal

axial strength of a column

P o = nominal axial load strength at zero eccentricity

p" (concrete anchorage) required tensile strength from loads

r, nominal axial yield strength ofa member, which is equal toF ),A g

p , total unfactored vertical design load atand above Levelx

PE = axial load on member due to earthquake

QE = the effect of horizontal seismic forces

R The response modification factor from Table 12.2-1

as set forth in Table J3.5-J or Table J3.6-1

I R )' = ratio of expected yield strengthstrength F y F )'cto the minimum specified yield

r rate of reduction equal to 0.08 percent for floors

No tation

S = design spectral response acceleration

I

= 0 6 (S os ITo) T+0.4(Sos),for Tlessthan or equal to T o

= (SOl )1 T ,for Tgreater thanT ,

So s = 5% damped,design,spectral response accele ration parameter at short

period (i.e.,0.2seconds)=(2 /3) S ,« - §11.4.4

S, = Mapped,MCE,5% damped,spectral acceleration parameter at short

periods (i.e.,0.2 seconds) asdetermin ed b §11.4.1

SOl = 5% damped ,design, spectral response acceleration parameter at I

l-second period=( 2 / 3) S sn

SI = Mapped, MCE,5% damped,spectral accelerationparameterfor a

l-secondperiod asdetermined in§11.4.1

s'II S = MCE,5% damped,spectral response acce leration parameter forshort I

periods (i.e.,0.2 seconds)=F oS ,. adj usted for site classeffects

I

S,I/I = MCE,5% damped,spectral responseacceleration parameter for

l-second period=F• SJ, adjusted for site classeffects

I

S RB S = section modu lusatthe reduced beam section (RBS)

S = spacilongitudinalng of shrear or toreinforcemen t, or ssion reinforcementpacingoftirn dansverse reiirectionparallel tnforcemento I

measured along thelongitudinal axis

I

T = self-straining forcearising from contractionor expansion resulting

fromtemperature change, shrinkage, moisture change, creep in

I

component materials,movementdue to differential settlement or

combinations thereof

T = ethe dlasticirectionfundamental peunder consideration, sriodof vibrationee §,1i1.4.5nseconds, offor limitationsthestructure in I

T o = a§pproximate fundamental p12.8.2.1 eriodas determined inaccordance with I

T, = SOl 1 Sos

I

I = thickness of flange

t w = thicknessof web

12 2 006 IB C Structural/Seismic D esign Manual , Vo l I

V c = (concrete)nominalshear strength provided by concrete

VDL, V u , V,ei, = un factored shear in frame member

v,,, = shear correspondingto the developmentof the"nominalflexural

v, (concrete) nominalshear strength at section

I

V" (steel)nominalshearstrength of a member

V p = (steel) shear strength of an active link

V pa = nominal shearstrength of anactivelink modified bytheaxial load

magnitude

I V px threquieportion of the seismic shear force at thered to betransferred to the componentslevel of the diaphragm,oftheverticalse

ismic-lateral-force-resisting system because ofthe offsets or changesin

I V , = stiffue(concrete)ssof the cnominal sompon ents ahear strengbovethprovidor belowedbythe dishear reinforcementaphragm

V " = (concrete anchorage) required shearstrength fromfactored loads

I

V" = (concrete) factored shear force atsection

v. = the seismicdesignstory shear (force) instoryx,(i.e.•between Levelx

andx-I)

2 0 06 I B St ructural /S eismic D esign Manual, V ol I 1 3

N otation I

w = thetotal effective seismic dead load (weight)defined in§ 12.7.2

and §12.l4.8 l

WI' = component operating weight

l1 ' c = weightsof concrete,in pcf

1 1'; , 11-' -r = that portion ofW located at or assigned to Level i orx ,respectively

w p = the weightof the smaller portionofthe structure

I

w p = the weightof thediaphragm andotherelements of thestructure

tributary to the diaphragm

I

l V p:c = theweightof the diaphragmandelements tributary thereto at

Levelx ,includingapplicableportionsof other loads defined in 1

11,= = column panelzone width

Z = (steel)plastic section modulus

z = height in structure at point of attachment of component, §13.3.1 I

Z e Ds = plastic section modulusat thereduced beamsection(RBS)

I(concrete) capacity-reduction or strength-reductionfactor

<I> =

<l>c = (steel)resistancefactor for compression

I

<1>, = resistance factor for shear strengthof panel-zoneof beam

-to-column connections

I

a = (concrete)anglebetween the diagonal reinforcement and the

longitudinalaxis ofa diagonally reinforcedcoup ling beam

14 2006 IBC Stru ctural/Seismic De sign Manu al, Vol

P = a redundancy factor determined inaccordance with §12.3.4

P = (concrete) ratio of non prestressed tension reinforcement(A s/b d)

Ph reinforcement ratio producing balanced strain conditions

I p = ratio of area of distributed reinforcementparallel to the plane of

p s = ratio of volume of spiral reinforcement to total volumeof core

(out-to-out of spirals) ofa spirally reinforced compressionmember

I p" ratio of area of distributed reinforcement perpendicularto the

plane ofA« ,to gross concrete area A c"

I = lightweight aggregate concrete factor; 1.0 for normal-weight

concrete, 0,75 for "all lightweight" concrete,and 0,85 for"sand

Ap = limiting slenderness parameter for compact element

I fo = length of radius cut in beam flange for reduced beam section

I flo (RBS) connection designdistancefrom columncenterline to centerline of hinge for RBS

f n = clear span measured face-to-face of supports

f ll' length of entire wall or of segment of wall considered in direction

of shea rforce

2 006 I BC Str uctural/S eismic D esign Manua l, V ol 1 5

Notation I

I

1- 1 coefficient offriction

deflections at the center of mass at the top and bottom or the storyunder consideration Note: Where ASD is used,8 shall be

1

computed using earthquake forces without dividing by 1.4,see

§12.12

I

8 a allowable story drift, as obtained from Table 12.12-1 for any story I

8 aA = allowable story drift for structureA

I

8 aB = allowable story drift for structureB

Ox = inelastic deflections of Level x - §12.8.6

I

O,WE the average of the displacements at the extreme points of the structure

at Level x

I

s, = the deflections determined by an elastic analysis of the

Active Fault/ActiveFaultTrace A fault for which there is an average historic sliprate of

I mm peryear or more and geologic evidence ofseismic activity within Holocene (past I 1,000years) times Active fault traces are designated by the appropriate regulatory agency and/or

registered design professional subject to identification by a geologic report

Allowable Stress Design A method of proportioning structural members, such that elasticallycomputed stresses produced in the members by nominal loads do not exceed specified allowablestresses (alsocalled working stress design)

Attachments, Seismic Means by which components and their supports are secured or

connected to the seismic-foree-resisting system of the structure Such attachments include

anchor bolts, welded connections and mechanicalfasteners

Balcony,Exterior An exterior floor projecting from and supported bya structurewithout

additional independent supports

Base The level at which the horizontal seismic ground motions are considered to be imparted

to the structure

Base Shear Total design lateral force or shear at the base

Boundary Elements Chords and collectors at diaphragm and shearwall edges,interior

openings, discontinuities,and re-entrant corners

Boundary Members Portions along wall and diaphragm edges strengthened by longitudinal

and transverse reinforcement and/or structural steel members

Brittle Systems,members,materials and connections that do not exhibit significantenergy

dissipation capacity in the inelastic range

Cantilevered Column System A structural system relying on column elements that cantileverfrom a fixed base and have minimal rotational resistance capacity at the top with lateral forces

applied essentially at the top and are used for lateral resistance

Collector A diaphragm or shear wall element parallel to the applied load that collectsand

transfers shear forces to the vertical-foree-resisting elements or distributes forces within a

diaphragm or shear wall

Component A part or element of an architectural, electrical,mechanical, or structural system

Component, equipment A mechanical orelectrical component or element that is part

of a mechanical and/or electrical system within or without a buildingsystem

Component, flexible Component, including its attachments,having a fundamentalperiod greater than 0.06second

2006 IBC Structural /Seismic Design Manual, Vol I 17

Component, rigid Component,including its attachments, having a fundamental

period less than or equal to 0.06 second

Confined Region The portion of a reinforced concrete component in which the concrete is

confined by closely spaced special transverse reinforcement restraining the concrete in

directions perpendicular to the applied stress

Coupling Beam A beam that is used to connect adjacent concrete wall piers to make them act

Dead Loads The weight of materials of construction incorporated into the building,including

but not limited to walls, floors,roofs, ceilings, stairways, built-in partitions, finishes, cladding,

and other similarly incorporated architectural and structural items, and fixed service equipment,

including the weight of cranes

Deck An exterior floor supported on at least two opposing sides by an adjacent structure, and/or

posts, piers, or other independent supports

Deformability The ratio of the ultimate deformation to the limit deformation,

High deform ability element An element whose deformability is not less than 3.5when

subjected to four fully reversed cycles at the limit deformation,

Limited deformability element An element that is neither a low deformability nor a

high deformability element

Low deform ability element An element whose deformability is 1.5 or less

Deformation

Limit deformation.Two times the initial deformation that occurs at a load equal to 40

percent of the maximum strength

Ultimate deformation The deformation at which failure occurs and which shall be

deemed to occur if the sustainable load reduces to 80 percent or less of the maximum

strength

Design Earthquake The earthquake effects that are 2/3 of MCE earthquake effects

Design Strength The product of the nominal strength and a resistance factor (or strength

reduction factor)

Designated Seismic System Those architectural, electrical,and mechanical systems and their

components that require design in accordance with Chapter 13 that have a component

importance factor, lp , greater than 1.0

Diaphragm, Flexible A diaphragm is flexible for the purpose of distribution of story shear and

torsional moment when the lateral deformation of the diaphragm is more than two times the

average story drift of the associated story, determined by comparing the computed maximum

in-plane deflection of the diaphragm itself under lateral force with the story drift of adjoining

vertical lateral-force-resisting elements under equivalent tributary lateral force

Diaphragm, Rigid A diaphragm that does not conform to the definition of flexible diaphragm

18 2006IBC Structural/Seismic Design Manual, Vol 1

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Total Design Displacement The design earthquake lateral displacement, includingadditional displacement due to actual and accidental torsion required for design of theisolation system.

Total Maximum Displacement The maximum considered earthquake lateraldisplacement, including additional displacement due to actual and accidental torsion,required for verificationof the stability of the isolation system or elements thereof,design of building separations, and vertical load testing of isolator unit prototype

Displacement Restraint System.A collection of structuralelements thatlimits lateral

displacement of seismically isolated structures dueto the maximum considered earthquake

Duration of Load The period of continuous application of a given load,or the aggregate of

periods of intermittent applications of the same load

Effective Damping The value ofequivalent viscousdamping corresponding to energy

dissipated during cyclic response of the isolation system

Effective Stiffness.The value of the lateral force in the isolation system, or an element

thereof,divided by the corresponding lateral displacement

Nonductile element An element having a mode of failure that results in an abrupt loss

of resistance when the element is deformed beyond the deformation corresponding to thedevelopment of its nominal strength.Nonductile elements cannot reliably sustain

significant deformation beyond that attained at theirnominalstrength

Equipment Support Those structural members or assemblies of members or manufactured

elements, including braces,frames, lugs,snubbers, hangers, or saddles that transmit gravity loadand operating load between the equipment and the structure

Essential Facilities Buildings and other structures that are intended to remain operational in theevent of extreme environmental loading from flood, wind, snow, or earthquakes

Factored Load The product of a nominal load and a load factor

Flexible Equipment Connections Those connections between equipment components that

permit rotational and/or translational movement without degradation of performance

2006 lac Structural/Seismic Design Manual, Vol. 19

Frame

Braced frame An essentially vertical truss,or its equivalent ,of the concentric or

eccentric type that is provided in a building frame system or dual frame system to resist

shear

Concentrically braced frame (CBF) A braced frame in which the members are

subjected primarily to axial forces

Eccentrically braced frame (EBF) A diagonally braced frame in which at least one

end of each brace frames into a beam a short distance from a beam-column or from

another diagonal brace

Ordinary concentrically braced frame (OCBF) A steel concentrically braced frame

in which members and connections are designed for moderate ductility

Special concentrically braced frame (SCBF) A steel orcomposite steel and concrete

concentrically braced frame in which members and connections are designed for ductile

behavior

Frame, Moment

Intermediate moment frame (IMF) A moment frame in which members and joints are

capable of resisting forces by flexure as well as along the axis of the members

Ordinary moment frame (OMF) A moment frame in which members and joints are

capable of resisting forces by flexure as well as along the axis ofthe members

Special moment frame (SMF) A moment frame in which members and joints are

capable of resisting forces by flexure as well as along the axis of the members

Frame System

Building frame system A structural system with an essentially complete space frame

system providing support for vertical loads Seismic force resistance is provided by shear

walls or braced frames

Dual frame system A structural system with an essentially complete space frame

system providing support for vertical loads Seismic force resistance is provided by a

moment-resisting frame and shear walls or braced frames

Space frame system A structural system composed of interconnectedmembers,other

than bearing walls,that is capable of supporting vertical loads and that also may provide

resistance to seismic forces

Gravity Load (W). The total dead load and applicable portions of other loads as defined in

§§ 12.7.2 and 12.14.8.1

Hazardous Contents.A material that is highly toxic or potentially explosive and in sufficient

quantity to pose a significant life-safety threat to the general public if an uncontrolled release

were to occur

Impact Load The load resulting from moving machinery, elevators, craneways, vehicles, and

other similar forces and kinetic loads, pressure, and possible surcharge from fixed or moving

Inverted Pendulum-type Structures Structures that have a large portion of their mass

concentrated near thetop and,thus, have essentiallyone degree of freedom inhorizontal

translation The structures are usually T-shaped with a single column supporting the beams or

framing at the top

Isolation Interface The boundary between the upper portion of the structure,which is

isolated,and the lower portion of the structure, which movesrigidly with the ground

Isolation System The collection of structural elements that includes individual isolator units,

structural elements that transfer force between elements of the isolation system and

connections to other structural elements

Isolator Unit A horizontally flexible and vertically stiff structural element of the isolation

system that permits large lateral deformations under designseismic load.An isolatorunit may

be used either as part of or in addition to the weight-supporting system ofthe building

Joint A portion ofa column bounded by the highest and lowest surfaces of the other membersframing into it

Limit State A condition beyond which'a structure or member becomes unfit for service and isjudged to be no longer useful for its intended function (serviceability limit state) or to be unsafe(strength limit state)

Live Loads Those loads produced by the use and occupancy of the building or other structureand do not include construction or environmental loads such as wind load,snow load,rainload,earthquake load, flood load,ordead load

Live Loads (Roof), Those loads produced I) during maintenance by workers,equipment, and

materials; and 2) during the life of the structure by movableobjects suchas planters and by

that more than one extreme load will occur simultaneously,

Loads Forces or other actions that result from the weightof building materials, occupants andtheir possessions, environmental effect,differential movement, and restrained dimensional

changes.Permanent loads are those loads in which variations over time are rare or of small

magnitude Other loads are variable loads (see also "Nominal loads")

Loads Effects Forces and deformations produced in structural members by the applied loads

2006 IBC Structural/Seismic Design Manual, Vol 21

Definiti ons

Maximum Considered Earthquake.The mostsevere earthquake effects considered b this

code

Nominal Loads.The magnitudes ofthe loads specified inthis chapter (dead,live,soil, wind,

snow, rain,flood, and earthquake.)

Nonbuilding Structure A structure, other than a building,constructed ofatype included in

Chapter 15 and within the limits of§15.1.1

Other Structures Structures,otherthan buildings,for which loads are specified in this

chapter

P-delta Effect The second order effecton shears,axial forces and moments offrame

members inducedby axial loads onalaterallydisplaced building frame

Panel(Part of a Structure).Thesection of a floor, wall,or roof locatedbetween the

supporting frameoftwo adjacent rowsof columns and girdersor column bandsof floor or

roof construction

ResistanceFactor.A factor thataccounts for deviationsof the actual strength from the

nominalstrength and the manner and consequences of failure(also called strengthreduction

factor)

Seismic Design Category.A classification assigned to a structure basedon itsoccupancy

category andthe severity of the designearthquake ground motion at the site,see §11.4

Seismic-fo rce-resisting system.The part of the structuralsystemthathasbeen considered in

thedesignto providethe requiredresistance to theseismicforcesprescribed herein

SeismicForces The assumed forcesprescribed herein, related to theresponse of the structure

to earthquake motions,tobe used in the designof thestructure and itscomponents

Seism icResponseCoefficient Coefficient C " as determined from §12.8

ShallowAnchors Shallow anchors are those with embedmentlength-to-diameterratios of

less than8

Shear Panel.A floor,roof,or wall componentsheathed to act as a shearwall or diaphragm

Shear Wall.Awalldesigned to resist lateral forces parallel to theplaneofthe wall

Shear Wall-frame InteractiveSystem A structural system thatusescombinationsofshear

walls and framesdesigned to resist lateralforces in proportion to theirrigidities,considering

interactionbetween shear walls and frameson alllevels

Site Class.A classification assigned to asite based on the types of soilspresentand their

engineering properties as defined in§11.4.2

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Dennlti ons

Site Coefficients.Thevalues ofF aandF

"indicated in Tables 11.4-1and 11.4-2, respectively.

Special Transverse Reinforcement Reinforcementcomposed ofspirals,closed stirrups, or

hoops and supplementary cross-ties provided to restrainthe concrete and qualify theportion of

the component,where used, as a confined region

Sto ry Drift Ratio.The story drift divided by the story height

Strength,Nomina l.The capacity ofastructure ormember to resistthe effectsof loads,as

determined b computationsusing specified materialstrengths and dimensions and formulas

derived from accepted principlesof structuralmechanics or by field tests or laboratory tests ofscaled models,allowing for modelingeffects and differenc esbetween laboratory and field

conditions

Streng thDesign A method of proportioning structural members such thatthe computed

forcesproducedin themembers by factored loads do not exceed the memberdesignstrength

(alsocalledloadand resistance factor design.)The term "strengthdesign" isused in the design

of concrete and masonry structural elements

Strengt h Required.Strengthofamember,crosssection, or connectionrequired to resist

factored loadsorrelated internal moments and forces in such combinations as stipulated by

these provisions

Torsiona lForce Distributio n.Thedistribution ofhorizontal seismic forces through a rigid

diaphragm when thecenter of massof the structure at the level underconsiderationdoes not

coincide with the center ofrigidity (sometimes referred to as a diaphragm rotation)

Toughness.The abilityof a materialto absorb energy withoutlosing significantstrength

Wall,Load-bearing Any wallmeetingeither of the followingclassifications:

I Any metalor wood stud wall that supports more than 100 poundsperlinear foot(1459 N/m) of vertical load in addition to its own weight

2 Any masonry or concretewallthat supports more than 200 pounds perlinear foot(2919 N/m) ofvertical load in addition to its own weight

Wall, Non load-bearing Any wall that is not a load-bearing wall

Wind-res t raint Seismic System.The collectionof structuralelements that provides restraint

of the seismic-isolated-structureforwind loads.Thewind-restraint systemmay beeither an

integral partof isolator units or aseparate device

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De finitio ns

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Example i • Classlficationllmportance Fact ors/Seismic Design C a t eg o r y §11.5 -1

Determine thefollow ing

[!J B uilding category and importance factors for general occupancy and for

one build ing to be used f or emergency she lter

[!J Seismic Design Category (SOC)

I C ~ /c ~ d / ~J ionsand Discussion

[!J Building category and importance factors

Cd ~e Referenc ~

From Table 1\.5- 1,"Importance Factors," for the given occupancy category, the generalcategory is II The occupancy category is used to determine the"Seismic Design Category,"

§11.6- 1 The one building tob used for an emergency shelter is Category IV

The importance factorsfor seismic loads are from Table 11.5-1 Importance factors for snowloads are fromTable 7-4 Importance factors for wind loads are from Table 6-1

Category

IIIV

SeismicFactorf

\.01.5

Snow

Factor1

\.01.20

§ 11.S· 1 Example i • Cla ssification /Impo rtance Fa ctors Sei smic Des ign C at egory

§ 1 1 6

~ Seismic Design Category

Allstructuresare assigned toaSeism icDesign Category (SDC) based o theirOccup ancy

Category andthe spectral response accelerationcoefficientsS o<andSOl,irrespective of the

fundamentalperiodof vibration of thestructureT. Each building and structure shall be

assigned to the mostsevere SDCin accordance with Table 11.6- Ior I 1.6-2as follows

Shelter

Recall: SI = 0.75% forthistable

*Note thatfor Occupancy CategoriesI, II, and III havingS,equal to or greater than0.75 (recallSj=

0.75),thebuilding shall be assigned toSDC E Also for OccupancyCategory IV havingS,~0.75,

thebuilding shall be assigned to SDC F

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E x a m p le 1 • Ear th q u ak e Lo ad Co m b i n ations : St rength Des ign §12 4.2 3

This example demonstrates the application of the strength design load combinationsthat

involvethe seismic loadEgiven in§12.4;2.3.This will be done forthe moment-resisting

frame structureshownbelo w

Beam A-B and ColumnC-D areelements ofthe special moment-resisting frame

Structural analysishas provided the follow ing beam moments at A,and the

column axial loads and moments atCdue to dead load, office building live load,

and left- to-right( ~) andright-to-left (-) directio ns oflateralseismic loading

D ead L oad L i v e Load L eft-to -R ight Ri ght-to-Left

( +QI;;) ( QI;;)

B eam Mome n t at A - 100 kip -ft -50 kip-f t +120 kip- ft -120 k ip-ft

Column C -D Axial L oad +90kips +4 0 ki ps +110 ki ps - 110 k ips

Column Moment a t C +40 kip- +2 0 kip -ft +160 k ip-ft -) 6 0 kip-It

Sign Convention: Positivemomentinduces flexural tension on the bottom side of a beam and

at the right side ofacolumn Positiveaxial load induces compression.Note that for the

particu lar location of Column C-D, theseism icAxial Load and Momentat C are both

positive for the left-to-right ( ~) load ing and are both negative forthe right-to -Ieft (- )

load ing This is not necessarily true for the other elements of thestructure

Find the following

ILJ Strength design seismic load combinations (Comb )

[!J Strength design moments at beam end A for seismic load combinations

[!J Strength design interaction pairs ofaxial load and moment for the

design of column section at C for seismic load combinations

2006 IBC Struc tural/Seismic Design Manual, Vol 27

§12.4 2.3 Example 1 • Earthquake Load Combinations: Strength Design

I

1.2D+1.3QE - (0.2)(1.1)D +0.5L =0 98D+ 1.3Q E+ 0 5L (Comb 5)

0.9D +1.3QE+(0 2)(1.1)D=1.I2D+1.3Q E (Comb 7) I

I

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when the signs of Q£andD are oppos ite.

By inspection, thegoverningseismic load combinationsare

whenthe signs ofQ £andD are the same,

0 68D+1.3Q E

whenthe signs ofQE andDareopposite

Streng th design moments at beam end A for seismic load combinations

~ For the governin g loadcombination whenthesignsofQ£ andD are thesame

M A=-323 kip-ft and+88kip-ft

2006 IBC Structur al /Se ism ic Design Manual, Vol 29

§12.4 2.3 Example 1 • Earthquake Load Combinations: Strength Design

[!J Strength design interaction pairs of axial load and moment for the

design of column section at C for seismic load combinations

as the axialload and moment at the column section C.These pairs must occursimultaneously because of a common load combination For example,both the axial

load and the moment must be due to a common direction of the lateral seismicloading and a common sense of the vertical seismic acceleration effect represented by

and D, while the moment algebraic signs are different This condition would prohibitthe use of thesame load combination for both axial load and moment

To include the algebraic signs of the individual actions, the directional property of thelateral seismicload effect Q E, and the independent reversible property of the verticalseismic load effect0.2SDsD ,it is proposed to use

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