Structural System for Tall Buildings

Other Books in the Tall Buildings and Urban Environment Series Casf-in-Place Concrete in Tall Building Design and Constructio~t Cladding Building Design for Handicapped and Aged Person

Council on Tall Buildings and Urban Habitat

S p o n s o r i n g Soclellcr

Internntlonul Asrocintion for Bridge a n d S w c t u r a l Engineering (IABSE)

American Society of Civil E n g i n e e n (ASCE)

American Inrtitute o f Architects (AIA)

American Planning Asrocintion (APA)

I n e r n a l i o n a l Union of Architects (UIA)

American Society o f Inleriar Designers (ASID) z~ I:.,, ; .,, ~;

Jnpon S t r u c t u n l Consultono Arrociotlon (ISCA) :; :.~

Urban Lnnd Institute (ULI)

International Fedemlion of lnlerior D c s i g n e n ( I R )

The following identifier those firms m d o r g m i w t i o n r w h o provide fartheCouncil's financivl s u p p o h

P a t r o n s

A1 Rnyes Group Kuwait

Consolidnted C o n t m a o r r Internulional Co Athens

Dnr Al-Hnndnsah '.Shnir & Panncrr." A m m a n

D L F Univcrsnl Limited N c w Dclhi

Zuhair Fnyez & Arrociales Jeddvh

Juros B n i m & Bolles N e w York

Kuwait Foundmion for t h e Advonccmcnt of Sciences Kuwait

Shimizu C o r p o n d o n T o k y o

T h e T u r n e r Corpomtion N e w Y a r k

Sponsors

Europrofilc Tecom Luxembourg

Gcorge A Fuller Co N e w York

T.R H n m r a h & Yeung Sdn Bhd Sclangor

HL-Technik A.G Munich

Hong Kong Lnnd Group Lld H o n g Kong

Kone Elevators Helsinki

John A M n n i n & Aaroc Inc L o r Angelcr

Snmrung Engineering Br Conrtruction Co Lrd Seoul

Snud Consult, Riyadh

Schindlcr Elevntor Corp Morrislown

Siecor Corporntion Hickory

Tukenako Corporation, T o k y o

Tishmon Conslruction Corporarion of N c w York, N e w York

T i i h m a n Speyer Properties N c w York

W c i r k o p i & Pickwonh N e w York

W i n g T a i Conrtmction &Engineering H o n g Kong

W o n g & Ouynng (HK) Lld Hong Kong

D o n o r 5

American Bridge Co Pittsburgh O'Brien-Kreilrbcrg & A S T O C ~ ~ ~ ~ C I In=

American Iron and Slcel Institute Pennrlukcn

\Vushington, D.C R T K L Associates Inc Bnltimore

W.R Grncc & Comp;my Cambridge Skidmore Ou,ingr & hlerrill Chicogo

Hnscko Corporaion T o k y o Steen C o n ~ u l t u n t r Pty Ltd., Singspore

T h c Herrick Corp Pleasnnton S y i k o & Hcnnery lnc N e w Y o r k

Hollundsche Belon Mnnlschappij BV, nornton-TomorcuilEngineer5 N c w York

Rijswijk Werner Vosr & Ponncrr Braunrchwcig

Hong Kong Housing Autl~orily Hong K o n g W o n g Hobach Luu Consulting Engineers L a 5

lffland Kivvnvgh Waterbury P.C New Y o r k Angcles

C a n l r i b u l o n

Office o f Irwin G C w l o r P.C., N e w York L i m ConsulU~tts Inc Cambridge H.K C h e n g & P n r t n e n Ltd Hung Kong Meinhnrdt Auslrnlin Pty Ltd Melbourne Douglas Specinlist C o n u n c t o n Ltd Aldridgc Mclnhnrdl (HK) Ltd H o n g K o n g

H n n Conrulwnt Grnup Snntn M o n i c a M u c r e r Rutledge Consulting Engincen The G c o r g ~ Hymnn C o n s W c l i o n Co N e w Y o r k

Balhrsdn Oboynshi Corpomtion T o k y o Ingenicurburo Mullcr Mnrl GmbH Mnrl O T E P In~crnntional SA Mndrid Institute S u l w n lrknndnr J o h o r Charles Ponkow Builders Inc Alwdenn INTEMAC Madrid Projcst S A Emprecndimentos e Servicos

J H S C o n s w e n o e Plnncjnmento Ltd S n o Tecnlcos Rin d c J n n c i m Pnulo P S M Inlernnllonnl C h i c a g o Johnson Fain a n d P e r r i m Asroc L o s Angeler Skilling W a r d Megnurson B n r b h i r c Inc

T h e Kling-Lindquist P m c n h i p Inc Senltlc Philadclphio Tooley & Company L a s Angcles LeMessurier Conrultnntr Inc Cnmbridge Nobih Y o u r r e f a n d Arrocinlcr L o s Angelcs

C o n t r i b u t i n g P n r t l c l p o n l r

Advnnccd Slructuml Concrplr Danvcr Advicrburnu Voor Bouwwchnick BV Amhcm Amcrirnn lwti~ute of Slecl Con.uu~Lion Chicago Anglo Amcricnn Pmpcny Scrviccr (Ply1 Lld lohnn-

"&burg Archituaml Scrviccr Dcpl Hong Kong Alelici D'Architcctum, dc Genvnl, Genvnl

~uslnlinn lnstitulc olSlccl Conrwcdon, hlllronr Poinl B.C.V Pmnctti S.r.1 Miiono . ~ ~ ~ -

w.S Bcllowr conrtriction Corp Hourton Aificd Bcncrch & Co Chicngo Balro dc lrnovclr Err Sno Poulo S.A Sno Poulo Bomhont & W a d Pty Lld Spring Hill

~ ~ ~ n y c r Wind Tunnci Labornlory (U Wcrr- u ~ d ~

cm Ontnriol London Bovir ~ i m i l i London Bnndow & Johulon ArrociaLcr Lor Angclcr Bmokc Hillier Porker Hong Kong Buildings & Dan S.A Bwsrclr CBM Engincm Inc Houston Ccrmo* Pcerkn Pacnen Inc Fon Coilinr

CblA A r h i t u ~ & Enginecn Sari luon

Conrfnction Conwlung L b o n l o r ) Dallor Cmnr Fuhicu Door Cu Lnkc Bluff Cmnc & Arloriolcr Ply Lld Sydnr) Da(11 Lugdon & Evcnll London DeSimonc Ch~plin & Dohr)n Inc Kc York

D O ~ A rlrlnc ~ ~ g l n r r n ~ ~ ~ n r scatllc Fujilnva l o h n s ~ n o n 1 A s ~ o c i l r r Cnlcagn Cunrndgc l i n l t n s k D n r ) Ply Ltd Sldnc)

Holn.5 Lundhcrg U'nrhlcr Inlcmolion~l Nc* YvrA

1io)ok;i~x Ar$ocialcr Lo, Anerlcr

I l r ~ l l l ~ ) Buildtng$ lnlrrn:l8vnll In: F ~ i d r i

l l ~ l t m ~ ~ h O h m & Klsrlboum lnc S 81, F i a n r 8 ~ ~ o lnlrrnaliond lmn k Slrrl Imlilutc Brulrcl$

Irwin Iohnrlon nnd Ponncn Sydncy

Infoc~er S.A Rio delnoeim

I.A loner Conruuction Co., Charlotic Kcsting Mnnn Iemigan RoacL Lor Angclcr

KPFF Conrulting Engineen Scuulc Lcnd Lwre Dcrign Gmup Lld Sydncy

~ n n i n & Bmvo, inc Honolulu Monin.Middirhrook & Louic Snn Fmncirco Enriquc Mmincr-Romcm S.A Mexico Mitchell McForlane Brrnlnoli & Paonen Inll LId Honk Kong

Miuubirhi Erwlc Co Ltd Tokyo Moh nnd Arrociau inc Tnipci Morrc Diesel Inlcmorionrl Ncw York Mvlriplci ConrWclions (NSWI Pfy Lid Sydncy Nihoasckkci U.S.A., Ltd., Lor Angclcr NiWIcn Sckkci Ltd Tokyo

Norman Dirncy & Young Brirhonc Pacific Adnr Dcvclopmenl Corp Lor Angclcr PcddlcThorp Aururlin Ply Lld Brirhnnc PorkTowrr Gmup New Yo*

Ccror Pclii & Asrociolu Ncw York Pcrkinr & Will Chicngo Rnhulnn Zain Arrociacr Kuolo LumDur

RFB Consulting Arrhilcnr, lohunnuhurp

Rnrrnunrrrr G m r ~ m m Cons Engrr PC llru York

E m r n Rod, & - ~, Sons lnd lnc New Yoik Rovon Woll8~mr D l r t r l & lruin 1°C Gurlph

S c p l l o t S a i o rcmnding (Sdnl Bhd, K ~ o l o Lumpur scrrrn S m : m r Gimi5 dc E n c r n h o n ~ S A Rlo dc lnncim

Scvcmd Asrociacr Conr Engn New York SOBRENCO S.A Rio d r Inncim south Africnn lnrtiatc of Srccl Conslrucdon Johm- ncrbvrg

stccl Rcinlorrcmcnt lnrlilulc of Aurlrnlio Sydncy STS Conrultnnu Lrd Nonhbmok

Studio Find Nova E Coslcilnni Milnno Tnyior Thornson Whining Ply Lld St Lconordr

B.A Vrvnroulu & Asrociacr Athenr VlPAC Encinrcn & Sricndru Lid hlclhovmc Worgon Cbpmon Pmnrrr S)uncy

Wndl~nl.cr A?ro:irlrl Nrw Yorl wond~.,d.cl,dc Con~.lurn, ~ r r Yolk

Other Books in the Tall Buildings and Urban Environment Series

Casf-in-Place Concrete in Tall Building Design and Constructio~t

Cladding

Building Design for Handicapped and Aged Persons

Semi-Rigid Connecrions in Steel Frames

Fire Sofery in TON Buildings

Cold-Formed Steel in Toll Buildings

Systems and Concepts

Structural Systems for

him B, Ki1,rzister Rpscard M I;o~~,aicz)k

Owerr bJanin Il'iliion! Afuibortnie Sciichi Ml,ra?lrofsll

AR,r~ad Rolrirnian Tltonras Scararrgeiio Roben Si,m Richard Ton!asefri

A )'atnohi

Editorial Group Ryszard M Kowalczyk, Chairman

R o b e r t Sinn, Vice-chairman

M a x B Kilmister, Editor

McGtaw-Hill, Inc New York San Francisco Washington D.C Auckland Bogoti Caracas Lisbon London Madrid MexicoClty Milan

Montreal New Delhi San Juan Singapore

ACKNOWLEDGMENT OF CONTRIBUTIONS

This Monognph uar prepxed h j Commillcc 3 (Slmctuml Syrtcm5)of ihc Council onToll Buitdlngr

and Urban Hnbitnt nr p ~ n o f the Tali Building, and Urban Environment Series Thc edtlonll gmup

$ b a s R)szxd hf Kowatcz)k, chairman; Rohen Sinn, ricc-chnirmln; and hlox B Kiimister, editor

Special ncknowledgmentir due more individuals whore n k u w ~ i p l s formedthe mjorconvibution UI the

chapters in his volume These individuals and the chnpters or sections lo which they conhibuled ore:

Chapter 1: Editorial Group

Chapter 2: Editorinl Group

Section 3.1: Editorial Group

Scction 3.2: Brian Cnvill

Section 4.1: Eiji Fukuzawn

Section 4.1: Seiichi Murnmulsu

Section 4.1: Ahmod Rohiminn

Section 4.2: Owen Mnnin

Sccdon 4.3: T Okorhi

Project Dercriptionr were conuibuted by:

T h e Office of Irwin Cantor

CBM Engineers, Inc

Ellisor and Tanner Inc

Kajima Design, Inc

KingiGuinn Associates

LcMessuricr Consulrunls lnc

Leriie E Roberlson Arnocintes

Nihon Sekkei Inc

Ovc Amp & Pamcn

Section 4.3: Thomu Scmngello Section 4.3: Richard Tomasetti Section 4.3: A Yamoki Section 4.4: Editorial Group Section 4.5: Editorial Group Section 5.1: William Melbourne Secdon 5.2: 1 D Bennettr Secdon 5.2: P H Doynwnnrn Chapter 6: Joseph Bums

Paulus Sokolowski, and Snnor Inc

Pcrkins and Will Roben Rorenwarser Asrocioter Sevemd Associnter

Shimizu Corporation Skidmore Owings and Merrill Skiliing Ward Magnurron Barkshire Inc Thomton-Tomaretti Engineers Walter P Moore and Asrocioter

COMMllTEE MEMBERS

Hcrben F Adigun Mir M Ali Luis Guillermo Aycardi Prnbodh V Bnnavnlkur Bob A Bcckner

Charles L Bcckncr George E Brandow John F Bmtchie, Robcn J Bmngmber Yu D By-

chenkov Peter W Chen Ching-Chum Chcm Pave1 Cirek Andrew Dnvidr John DeBremoekcr,

Dirk Dickc Robcn 0 Disque Richard Dziewolnki Ehun Fang Alexander W Founleh James G

Forbes Roben I Hanren Roben D Hnnsen Toshihnm Hisatoku Arne Johnson Michael Kavyr-

chine Mnn B Kiimirler (editor) GcnF Konig Ryszwd M KowaIczyk (chairman) Juraj Korak

Monsieur G Lacombe Siegfried Liphardl Miguel A Mneiar-Rendon Owen Mnrrin Jaime Mn-

son N G Mutkov Gerardo G Mayor Leonard R Middleton Jaime Munoz-Duquc Jacques

Nasser Anthony F Nnrretta Fujio Nirhikown Alexis Ortapenko Z Powlowski M V Parokhin

Peter Y S Pun Wcmer Quoscbnnh Govidan Rahulan Anthony Fracis Roper Sntwant S Rihai

Leslie E Robenson Wolfgang Schurilcr Duiliu Sfintesco Robert Sinn (vice-chairman) Ramiro

A Sofronie A G Sokolov Euuro Suzuki Bungaie S Tnranalh A R Tonkley Kenneth W Wan

Morden S Yollcr Nobih F G Yourrcf Stefan Zucrek

GROUP LEADERS

The committee on Structural Systems is part of GroupSC of the Council, "Systems and Concepts."

The leaders are:

lamer G Forbes Chairman Joseph P Coluco, Vice-Chairman Henry J Cownn Editor

Foreword

This volume is o n e of a series o f Monographs prepared under the aegis o f the Council

on Tall Buildings and Urban Habitat, a series that is aimed a t documenting the state of the art o f the planning, design, conslruction, and operation of tall buildings as well as their interaction with the urban environmenL

T h e present series is built upon an original set of five Monographs published by the American Society of Civil Engineers, as follows:

Volume PC: Plnrming nrzd En~rironn~enral Crirerio for Toll Beildings Volume SC: Tall Building Sysrems ond Cortceprs

Volunze CL: Tall Building Criteria nnd Loading Volume SB: Srrucrurol Design of Toll Sreel Btrildings Voltrme CB: Srmcrural Design of Tall Concrele and Mosorrry Buildings

Following the publication of a number of updates to these volumes, it was decided

by the Steering Group o f the Council lo develop a new series It would b e based on the original effort but would focus more strongly o n the individual topical committees rather than the groups This would d o two things It would free the Council committees from restraints as t o length Also it would permit material on a given topic to reach the public more quickly

T h e result was the Toll Buildings and Urban Enr,iron~nenf series, being published by McGraw-Hill Inc New York T h e present Monograph joins s i x o t h e r s , the first of which was reieased in 1992:

Cost-in-Place Concrere in Toll Building Design ond Consrrucrion Clodding

Building Design for Handicapped ond Aged Persons Fire Safely in Tall Buildings

Senxi-Rigid Connecrions in Steel Frornes Cold-Formed Sfeel in Tall Buildings

This parlicular Monograph was prepnrcd by the Council's Committee 3 Strucmral Systems Its earlier treatment was n part of Volume SC I t dealt with the many issues relating t o tall building structural systems when it was published in 1980 T h e com- mittee decided that a volume featuring cane studies of many of the most important buildings o f the lust two decades would provide professionals with some interesting comparisons of how and why structural systems were chosen T h e result of the com- mittee's cfforls is this Monograph It provides case studies of tall buildings from Japan the United States Malaysia Australia New Zealand Hong Kong Spain, and Singa- pore This unique international survey examines the myriad o f archirecturni engineer- ing, and construcdon issues that must b e taken into account in designing tall buildtag structural systems

Preface

Although tall buildings are generally considered to be a product of the modem indusui- alized world inherent human desire to build skyward is nearly as old as human civi- lizntion The ancient ovramids of Giza in Eevot, the Mavan temdes in Tikal Guata-

this instincL Skyscrapers in thc modcrn sense began to appear over a century ago; how- ever, it was nnly after World War I1 that rapid urbani'ration and population growth cre- ated the need for the conswction of tall buildings

T h e dominant impact of Llll buildings on urban landscapes has tended to invite con-

acteristic and symbolic lrstaments to thc cities' wealth and their inhabitants' collecti!,e The ordinary observer recognizes the tall building primarily with respect to its exte- rior architectural enclosure This is nnly natural, as when we consider the great pyra-

~~~ -~ -, - -

that we have begun to realize the creativity and colossal effnn expended by these an- cient people to erect these swcmres in the desert at that time So it is with the modem skvscrao;r The overall soatial form as well as the intricate deWiline of the claddine svs-

the overall urban environment The aim of this Monograph, however, is to have a look under the outer covering of the building to reveal the stiuctural skeleton as well as to provide historical knowledge documenting the design and construction techniques used

to realize these monuments in today's world

This Monoeraoh is therefore dedicated to the structural systems for tall buildings:

to allow the tower to be realized safely andcfliciently As in the pas!, new nchievoments

paths toward more sophisticated and elcgant swcturnl syslems for wll buildings The rwctuml system organization chosen for a p d c u l a r project determines the fundamen- [at oropcnies of the aver;lll buiidinc the behavior under imposed loads, its safety, and

is lo demonstrate the chmcteristic features of many outstanding syslem form5 while documenting the faclors leading lo their selection for projects aclually realized

can be described as a completed whole Every month new buildings are being designed and created, new projects conceived, and new schemes applied Nevcnheless, we hope

Council to expand the chapters of the original Monograph into separate volumes The

building swctural systems conuibuted by leading engineers and design firms of the

xiv Preface

profession was conceived during the committee workship in Hong Kong in 1990 It was

only after estnblishina the editorial lendershir, for the work that the volume began to

takc form, will1 tlte scope and content of the book finallred At this time a buildinf data

form wns prepared for collecting thc most essential inform3tion concerning the struc-

s ~ o n s e s c o m ~ i l e d bv Max filmister This material reoresen& the core of the comoleled

of the compilation in the summer of 1993 in order to finish the completed volume in

time for publication

the information included may b e presented lo a broad professional audience This ex-

change of information is one of the tenets of the Council and is in fact a condition for

progress in the design of tall buildings

J C K Cheung is gratefully acknowledged, as is the Australian Research Grants Com-

mission for its suppon of the fundamental research

As mentioned, we are aware that everyday Progress is made in the field of structurnl

writing the Council or ioining the commitke

book to him

Robert Sirm Vice-Cltoimmn

3.1 Composite Sleel Floor Systems

3.2 Presmssed and Porttcnrioned Concrete Floor Systems Project Dereriptionr

Melbourne Ccnuvl

Lulh Hcndqumers Building Riverside Centcr

Bourke Plncc Cenuvl P l m One

Casielden Ploce

Majestic Building Telecorn Corporate Building

Trade Centcr

181 West Madiron Sueet

AT&T Corpamte Cenler

Two Union Squorc

F i s t Intersmte World Center

Hong Kong Bank Headqumers

4.6 Condensed ReierencesiBibliogmphy

5 Special Topics

5.1 Designing lo Reduce Perceptible Wind-Induced Motions

5 2 Fire Prolection of S w c t u n l Elements

5.3 Condensed RcfemnccdBibliognphy

6 Systems for the Future

6.1 A~hiEhilecedTendencies 6.2 Slructural Tendencies 6.3 Other Tendencies

Project Descriptions

Miglin-Beiller Tower Deurbom Ccnter Bnnkof thc SouthwertTowcr

Shimiru Super High Rise

6.4 Condensed RclerenceslBibliogmphy

Current Ouestions, Problems, and Research Needs

Nomenclature

Glorrury Symbols Abbreviudonr Units

Contributors

Building lndex

Name lndex

Subject lndex

Structural Systems

Introduction

Smctural s y s t e m for tall buildings have undergone a dramatic evolution throughout the orevious decade and into the 1990s Developments in structural system form and orgnnirntion h m e historically been realized as a rcsponse to as well as an impclus

toward emerging architectural uends in high-rise building design At thc time of pub-

international style and modernist high-rise designs, chanclerized by prismalic, repcti- live verticnl geometries and flat-topped roofs, were predominant (Council on Tnll Buildings Group SC 1980) The devclopmcnt of Lhc prototype tubular systems for lnll buildings was indeed predicated upon an ovcrall building form of constnnt or smoothly varying profile A representative office building project from the period is shown in R g 1.1 The rigid discipline of the cxterior rower form has since becn rcplaccd in many cases by the highly articulated vcnical modulations of rhc building envclopc characleristic of eclrclic postmodern deconslructivist, and nrohistorical high-risrexpressions (Rg 1.2) This general disconlinuily and erosion of thc cxterior facade has led to a new generation of tall building struclural systems that respond lo the more flexible and idiosyncratic requirements of an increasingly varied architec- tural aesthetic Innovntive s w c t u r a l systems involving megaframes, interior super- diagonally braced h m e s , hybrid steel and high-strength concrete core and outrigger systems, artificially damped structures, and spine structures nre among the composi- tions which represent a step in the development of structural systems for high-rise buildings This Monograph seeks to further the plncement of some of the most excit-

One of the fundamental goals of the Council has been to continualiy develop a tall buildings dambase The members of Committee SC-3, Structural Systems, decided

tural systems, the Monogmph would be organized with respect to such a database-type

tee thererore requested detailed informarion from engineers in Lhe profession, regard- ing the structural design of some: of the most innovative high-rise projecrq throughout

vided very spucific engineering informntion such as wind nnd seismic Iondingz dynamic propenics materials, and systems for a wide range of intcrnalional high-rise oroiecls, both comoleted and in o&oosal staee which i r e comoiled in this single

2 Introduction [Chap 1 I Chap 11 3 I

b e of interest and value to practicing engineers and architects as well as other tall

building enthusiasts

This Monograph is organized into six chapters A general introduction to the clas-

sification of tall building structural systems is found in Chapter 2 The section begins

to define the parameters and characteristics for which tall building systems are evalu-

ated Tall building floor systems arc discussed in Chapter 3, which includes recent

Fic 1.1 Ouolicr Onb Tuwcr Chicuco Illinois Comnleted 1984 I C c ~ ~ , n r s ~ ~ : .- Skirln,oru O w i n ~ r " &

4 Introduction [Chap 1 ,

: , , , 1 ' ;.!

developments in posttensioned concrete floor systems for high-rise construction in

Australia Structunl systems for tall buildings have historically been grouped with

Load Resisting Systems." forms the core of the work, with system descriptions for

nver 50 - - oroiects The oroiects are arraneed within five basic subclassifications for lat- r~ - -

ceded by a general introduction outlining the system forms limimtions, advantages,

and applications Chapter 5 discusses special topics in high-rise building structural

systems It presents infor!nation concerning the developing topics of wind-induced

motions and fire protection of structural members in tall buildings The concluding

Chapter 6, in dealing with systems for the future, presents examples of projccts on the

drawing board and proposals which represent innovative state-of-the-art structural

designs for tall buildings

Classification of

Structural Systems

Council on Tall Buildings Group SC 1980 Toll Btrilding Syrlerm ond Conceplr

The Council definition of a tall building defines the unique nature of the high-rise proj- ect: "A building whose height creates different conditions in the desieo, construction

the practicing structural engineer, the cataloging of suuctuial systems for tall buildings has historically recognized the primary importance of the system to resist lateral loads

any suuctunl systems methodology

In 1965 Fazlur Khan (1966) recognized that this hierarchy of system forms could

be roughly categorized with respect lo relative effectiveness in resisting lateral loads

cient for buildings in the range of 20 to 30 stories; at the other end is the generation 01 tubular systems with high cantilever efficiency With the endpoints defined, other sys- tems were placed with the idea that the application of any panicular form is economi- cal only over a limited range of building heights The system charts were updated periodically as new systems were developed and improvemcnts in materials and analysis techniques evolved

Alternatively, the classification process could be based on cenain engineering and systems criteria which define both the physical as well as the design aspects of the building:

Material Steel Concrcte Composite Gravity load resisting systems Floor framing (beams, slabs) Columns

loging of tall buildings with respect to their structural systems (Falconer nnd Beedle

1984) The classification scheme involves four distinct levels of framing-oriented

division: primary Framing system, bracing subsystem floor framing, and configuration

TYPE I I TYPE 11 I I TYPE Ill 1 ) TYPE IV I

and load transfer These levels are further broken down into subgroups and discrete systems (Fig 2.2) This format allows for the consistent and specific identification and documentation of tall buildings and their systems the overriding goal being to

hieh-rise environment

~~~ =~~ ~ ~ - - ~ While any cataloging scheme must address the preeminent focus on lateral load resislance, the load-carrying function of the tall building subsystems is rarely indepen- dent The most efficient high-rise systems fully engage vertical gravity load resisting elements in the lateral load subsystem in order lo reduce the overall structural pre- mium for resisting lateral loads Some degree of independence is generally recognized

Framing systems

framing subsystems

Building configuration and load transfer

(XX YY 2)

Elevation

Fig 2.2 Clvrrilicoliun of rlrurlurul syrlernr (Folnl,ler rrnd Beedlr 1984.1

8 Classification of Structural Systems [Chap 2

3 Falconer and Beedlc 1984 Clarrlficnr!on of Toll Bulldlng S),srem

Tall Building

Composite floor systems typically involve simply supported structural steel beams joists, girders, or trusses linked via shear connectors with a concrete floor slab to form

&I effective T-beam flexural member resisting primarily gravity loads The versatility

of the system results from the inherent strength of the concrete floor component in compression and the tensile seeneth and spannabiliw of the steel member ~ o m o o s i t e flw; system are advantageous because ofreduced material costs, reduced labor i u e to prefabrication, faster couslruction times, simple and repetitive connection details

reduced building mass in zones of henvy scismic activity The composite floor system slab element can be formed by a flat-soffit reinforced concrete slab, precast concrete planks or floor panels with or without a cast-in-place t o ~ ~ i n e - slab o r a metal steel

membcr is combined with a composite metal deck and a concrete floor slab, an

men1 is due to shear studs welded directly through the metal deck, whereas the compos- ite action of the metal deck results fmm side embossments incorporated into the steel sheet profile The slab and beam arrangement typical in composite floor systems pr* duces a rigid horizontal diaphragm, providing stability to the overall building system while distributing wind and seismic s h e m to the lateral load resisting system elements

1 Composite Beams and Girders

Steel and concrete c o m ~ o s i t e beams mav be formed either bv com~letelv encasine a ~~ steel member in concrete, with the composite action depending on the natural bond caused by the chemical adhesion and mechanical friction between steel and concrete

or by connecting the concrete floor to the top flanee of the steel frnmine member throueh shear c&nectors (Fie 3.1) The concrete-encased comoosite steelienm was - - ~~ - ~~~ ~

9

10 Tall Building Floor Systems [Chap 3

floor systems is a rolled or built-up steel beam connected to a formed steel deck and

concrete slab The metal deck tvnicallv roans unshored between steel members while - - ~~ ~ -

also providing a uorking platlonn for steel erection The met31 deck slab may be ori-

enled parallel or perpendicular lo the compo>ite beam span and may ilself be either

floor that is framed in composite steel beams

In composite beam design h e stress distribution at working loads across the com-

normally quite near h e neutral axis and consequently lightly stressed, a number of built-

up or hybrid composite beam schemes have been formulated in an attempt to use the structural steel material more efficiently (Fig 3.4) Hybrid beams fabricated from ASTM A36 grade top flange steel and 345-MPn (50-hi)-yield bonom flange steel have

In all of these cases however the increased fabrication costs must be evaluated which

gauge top flange must be provided for proprr and rffr.cli$,e shex slud isslallalion

types of composite floor framing types ( I ) The mcmbcr !nus1 bc designed for the maximum bending momenl near midspan and thus is oRcn undcrs!rrs,ud near h e sup-

Fig 3 2 Three First Nntionol Plnm, Chicago, Illiooir, lyplcnl noor

Fig 3.3 Composite beam stress dirlribution

I :>,i;~

ancles leadinc to hirher fabricatton costs) to allow access for this c s u i ~ m e n t For this - u -

reason, a number of composite girder forms allowing the free passage af mechanical,

ducts and related services through the depth of the girder have been developed They'

include tapered and dapped girders, castellated beams, and stub girder systems (Fig

3.5) As the tapered girders are completely fabricated from plate elemenls or cut from

rolled shapes, these composite members are frequently hybrid, with the top flange

designed in lower-strength steel Applications of tapered composite girders to office

building construction are limited since the main mechanical duct loop normally runs

through the center of the lease span rather than at each end The castellated composite

beam is formed from a single rolled wide-flange steel beam cut and then reassembled

by welding with the resulting increased depth and hexagonal openings These mem-

bers are available in standard shapes by serial size and are quite common in the United

Kingdom and the rest of Europe Use in the United Stales is limited due to the

increased fabrication cost and the fact that the standard castellated openings are not

large enough to accommodate the large mechanical ductwork common in modern

high-rise, large floor plate building construction common in the United States The

stub girder system involves the use of short sections of beam welded to the top flange

of a continuous, heavier bottom girder member Continuous transverse secondary

beams and ducts pass through the openings formed by the beam stubs This system has

been used in many building projects, but generally requires a shored design with con-

sequent construction cost premiums

HYBRID

ROLLED

Succc$si~ll cnmpnwte hc:m ile.;ign T'LII.IIL.\ the c ~ n s i d e r i ~ t i o ~ t n i \.ilriol~< <cr\ic~.- ability ~*.os; >o;b ;IS I~rnn-tsr~tt (clsupl denc:ti~rns ;lnJ nuor vihr;dinns 0 1 p3rticul;tr cunccrn is lltc iw.c oi pcrc~ptihility of n:cupaot-indursd tl~tnr r ~ h r ~ l ~ o n s The rsln- lively l!i;lt II~.rur;ll ~ l i l l n c r ~ oi a1o.l nltnporilc noor fr;lming a)slr.m> rerulls ill rela-

t i t c h lot !ihralion :~!#,t>litndrc irnm 1r.losilory hcel-dlop d ~ ~ i l : l t ~ o n s and thcr:lore is effective in reducing perccptihility Recent studies have shown that short 17.6 m (25 fi) and lcss] and rery lollg clcar-sp;ln 113.7 nl (45 St) and longer] cunlposile floor framine svstcnls ncriornl suite well and - :!re rarely found to transmit annoying vibra-

tions to the occup8tnts Particular care is requircd for span conditions in thc (9.1- to 10.7-m) 130- to 35-ftl rangc Anticip.atcd danlping provided by partitions which extend

to the sl:lb cthovc serviucs ceiling constructiot~,and the structure itself are used in conjunctiott with htate-of-thc-;lrt prediction tllodels to evalue~e thc potential for pcr- ceptible noor i~ibrations

2 C o m p o s i t e J o i s t s and T r u s s e s Preeneinccred nronrictnrv oncn-web lloor ioists ioisl rirders and fabricated noor = -

trusses are viable composite memhcrs when combined with a concrete noor slab The

stiffnus;due to 1he.decocr s~ructural ~ ~ den& =ncl case in nccomrnodatine electrical con- -

duit plumbing pipes and heating and air-condilioninp ductwork Open web systems

14 Tall Building Floor Systems [Chap 3

the member Open-web steel joists have been used in composite action with flat-soffit

concrete slabs and metal deck slabs supporting concrete fill with and without sheer

conhectors The desien for these svstems i s orimarilv based on manufacturers' test

d313 , I s ~ ~ p ' n - ~ v e b steel jotbtb and joist girders nornlally are \paced relatively clusaly

rile full polenrial lor composite elilc~cncy is not rcalircd as conlpared to o1hr.r cunlpor-

ite floo; systems Composite design does provide quantifiableadvantages over "on-

lively long-span 3pplicntions svtlh rn;lxinlom f l e a ~ h ~ l i t y fnr iscorporaung huildinz-ser-

\,ic<r dusluork and oioina into tilu cellinr! caritv The urufill: of the truss lorm alluhi, - -

for large mechanical air ducts as well as other piping and electrical lines to pass

through the openings formcd by the lriangularization of the web mcmbcrs T h e

increased depth of the comuosite truss svslcm over a standard rolled-shaoe comnosite

results in maximum material eificicncy and high flexural stilfness Generally, com-

posite floor trusses are considcrcd economically viable lor floor spans in excess of

about 9 m (30 it) A iurtltcr requirement Tor noor truss systems is that the Framing Iny-

out be uniform resuldng in relatively few truss types, which can be readily built in the

floor truss assemblage Lends to ofissct the relative material eliicicncy For this reason,

composite floor truss systems are particularly nttractive in high-rise uiiice building

applications where large open lcnsc spans are required and noor configurations arc

generally repetitive over the ltcight of the building Figure 3.6 shows an example of a

project utilizing composite noor trusses as part of an o\,erall mixed steel and concrete

building irante

cated noor truss: however the Warren w s s , with or without web verticals, is the one

open-web area to acco&modate ducta,ork and piping Vertical wdb membcrs added to

the Warren truss or a Pratt truss geometry may be utilized when the unbraccd length

the main air-handling mechanical buct loop in office building applications The spac-

-

unbraced lensth On the other hand the nnlle =~~ of ~~ the web diaeonalr should L~~~ ~ be made

~

lengths and higher member axial forces, often requiring connection gusset plates

thereby increasing iabrication costs and decreasing the clear area for ductwork and

piping A panel spacing of roughly two to three limes the truss depth is a good rule of

thumb for orienting web diagonals The floor truss configuration should be detailed

member may be introduced into the truss girder geometry Lo transfer these imposed

shear loads into the truss svstcm

gle-angle sections to allow easy, direct connection of web mcmbers without gusset

althouih tube sections lhive been used The composiie floor truss system is &mpleted

through the direct connection of the top chord flange to the concrete floor sl-b by

shear connectors The most common floor system in building construction is a com- oosite metal deck and concrete slab chosen based on fire seoaration and acoustical requiremenu spanning between composite floor trusses The floor trusses are normally spaced such that the metal deck slab sonns as the concrete form between the trusses without requiring any additional shoring

CONCRETE FLOOR SYSTEMS

low-rise SlNCtUreS such as parking garages and shopping centers Precast pretensioned floor units have remained popular since the 1960s and cast-in-place posttensioned

Poslrensioncd floors have been widely uscd for high-rise office buildings in Aus- tralia since the cnrly 1980s and there are examples in the United States, the most

ing in the world when completed

EXTEA1OR STEEL C O U P O S ~

GR4VITI COLUMNS AIIb SPANDRELS

16 Tall Building Floor Systems [Chap 3

7 General Considerations

High-rise oftice buildings usually have long-span floors to achieve the desirable col-

umn-free space, and the spans are usually noncontinuous between the core and the

facade To achieve long spans and still maintain acceptable deflections requires a deep

floor system in steel or reinforced concrete However, by adopting prestressed post-

m u m m

WARREN TRUSS

CHOilOB h u b l ~ l n g l e m R e e ? T U k R L U b

WEB MEMBERS IL.% IL %

Fig.3.8 Composite trurr romponcnleections

I '

free s b c e is not a selling point;the tenant or buyer ices the spice already subdivided

b y walls, which effectively hide the columns Hence continuous spans can b e achieved Unlike office buildings, residential buildings do not as a rule have sus-

fit or a plasterboard ceilina on battens fixed to tbe slab soffit Flat-plate floors are

mizing the slab thickness while at the same time controlling deflections

buildings, precast pretensioned concrete can be used and has been employed in some buildines described in this M o n o m p h (Luth Building: Mnrriott Hotel, New York; Tai

slabs is the cranage required to lift the heavy uniu along with the field-welded connec-

are usually tied together by and made composite with a thin cast-in-place topping slab Floor posttensioned systems use either 12.7- or 15.2-mm (0.5- or 0.6-in.) high-

where individual strands are greased and sheathed in plastic, or "bonded," where groups of four or five strands are placed inside flat metal ducts that are filled with Eement eroul after strcssina On a worldwide basis, bonded systems are preferred in high-rise buildings becausithey have demonstrated better long-term du&bility than unbonded systems Although unbonded systems used today have improved corrosion resistance compared to earlier systems, there is still a large number of older buildings that exhibit corrosion problems in their unbonded tendons Another reason that bonded posttensioned systems nre preferred is that cutting tendons for renovations or demolition is both simpler and safer when the tendons are bonded to the concrete Nevenheless, care musibe exercised as it is by no means unknown for tendons speci- fied to be grouted to have had this vital operation omitted In this aspect good quality control is essential Figure 3.9 illustrates a typical posttensioned floor using unbonded tendons, whereas Figs 3.10 and 3.11 illustrate the construction of a typical postten- sioned floor using bonded tendons

Posttensioned flat slabs and flat plates (Fig 3.12) Posttensioned beams supporting posttensioned slabs (Fig 3.13) Posttensioncd benms supporting reinforced concrete slabs (Fig 3.14) Currently with computer programs readily available to carry out cracked section analysis of prestressed concrete, it is normal to design for partial prestress where the

comprises a significant portion of the total reinforcement The partial prestress ratio (PPR) gives the degree of prestress

+ A,&,

ride culficicnt prestress lo lh313ncc oboul 1 5 % of the self-weight of the nnor blrUclllrLI

in a PPR of about 0.6.) Deflections and shear capacity must also be checked:

I /

internal span and 40 for an end span

!

In high-rise buildings it is preferable to avoid running floor beams into heavily reinforced perimeter columns for two reasons:

space with the column reinforcement

2 Frame action developed between the beams and columns causes the design bending

the number of identical floors that can be designed, delailed and conswcted

Instead of being directly supponed by columns, the floor beams should be supported

by the spandrel beams

Prestressing anchorages can be on the outside of the building (requiring external access) at a step in the soffit of the beams [see Riverside Centre and Bourke Place

ets have the disadvantage that they usually cause local vnrialions in the flatness o i the floor and rough patches, which may need to be ground flush

Bccause posttensioning causes axial shortening of the prestressed member, it is necessary to consider the effects of axial reslraint, that is, the effects of stiff columns

20 Tall Building Floor Systems [Chap 3

and walls Such restraint has two potential effects: it can overstress the co!umns or

walls in bending and shear, and it can reduce the amount of prestress in the floor

axial shortening of the floor can be generally in a direction toward the core This

means that the perimeter columns move inward, but because they move by the same

the first story abuus a nonprestressed,floor, which is often the ground floor As this*:'

,lev is usually higher than a typical ,tory the flexibility of rhc columns is greater and

1111: induced bdndinp mo~nents [nay be easily accommodated Horvevsr the loss of prc-

2 Economics of Posttensioning

Posttensioned concrete floors will usually result in economics in the total construction

cost because of the following:

The last item can be very significant as any height reduction translates directly into savings in all vertical structural, architectural, and building-services elements The construction will proceed wilh the same speed as a normal reinforced concrete floor, with four-day floor-to-floor construction cycles being achieved regularly on high-rise office buildings with posttensioned floors (Fig 3.18) Three-day cycles can easily, be achieved using an additional set of forms and higher strength concretes to shorteb posttensioning time

A major cost variable in posuensioned floors is the leneth of the tendons ~ Short

trend for tendons ranging front 10 to 60 m (33 to 200 it) Tlte relntively high cost of short tendons rssults from fixcd-cost components such as setup costs, asohorapcj, and

"retli~tg losses" is also greater with ruv shun strands, thus incrc3sing the area of ten- don required Nevertheless, even though most tendons in a high-rise building floor will be only around 10 to 15 m (33 to 5 0 it), the system is economical because of sav- ings in floor depth, and it is desirable because of control of deflections and the lack of need for precambering For grouted tendons the optimum economical size has been

,, ~ round to b e the four- or five-strand tendon in a flat duct because the anchorages are compact and readily accommodated within normal building members and because

2 2 Tall Building Floor Systems [Chap 3

Comparing the cost of bonded and unbonded tendons will generally show the

unbonded system as being slightly cheaper This is because unbonded posttensioning

usually requires less strand due to lower friction and greater available drape Unbonded

strand also does not need grouting with its costs of time and labor As a floor using

ultimate flexural strength and code requiremcnls, the combined cost of the strand and

untensioned reinforcement will be almost the same as that for bonded systems

try and irregularities For example:

The higher the perimeter-to-area ratio, the higher the normal reinforcement content

since reinforcement in the perimeter can be a significant percentage of the lolal

more difficult lo form

Inlernal stressing from the floor surface increases costs due to the provision of the

wedge-shaped stressing pockes and increased amounts of reinforcement

Slab steps and penetrations will increase posttensioning costs if they decrease the

length of tendons

1 , Ssct 3.21 Prestressed and Posttensioned Concrete Floor Systems 23

Tall Building Floor Systems [Chap 3 S e c t 3.21

stressed strands and tendons during structure modifications or demolition Although

.,.:

Finding the tendons in a floor to permil the localbn of penetrations without damaging

any tendons is a very simple procedure that is carried out with the aid of an electronic

tendon locater Tendons are accurately located using this system withon1 any need to

remove floor coverings or ceilings

Concrete Reinf + P.T

Bl3.C R P.T

Floor being poured7

Full access for Finishing Trades

Average tendon length, rn

Fig 3.19 Portlenrianing corb

26 Tall Building Floor Systems [Chap 3

In a typical posttensioned floor it is possible.to locate penetrations of up to 1000 by

tion to the floor Penetrations that require cutting of the posttensioned tendons will

need lo be checked and designed as would any large penetration in any floor system

1 Design the modified floor s m c t u r e in the vicinity of the penetration, assuming

that any cut posttensioned tendons are dead-ended at the penetration

2 Install any strengthening required

4 If there is no doubt as to the quality of the grouting, proceed lo step 5 Other-

wise strip off ducting, clean out grout, nnd epoxy grout the strands over a length

of 500 mm (20 in.) immediately adjacent to the penetration

5 Install props

6 Core drill the corners of the penetration to eliminate the nced for overcutling

and then cut the perimeter using a diamond saw

sion

If a large penetration through a floor cannot be located within the slab area but

must intersect a primary support beam, then substantial strengthening of adjacent

beams will usually be necessary

Whcn culling openings into floors built using unbondcd postlensioned tendons the

procedures used for bonded posttensioned tendons cannot bc applied The preferred

procedure that has been developed to permit controlled cuttinf of unbondcd strands is

i to use a special detensioning jack The jack grips the strand and the strand is then cut with the force in the strands being released slowly New anchorages are then installed

at each side of the new opening and the strands restressed

Extensive experience has been gained in demolition procedures for posllensioncd

for demolition are the same as for reinforced concrete The individual strands will not

lition The individual cut strands will dislodge at stressing anchorages, but will move

generally less than 450 mm (18 in.) However, precautions should al!i~ays be taken in

case the strands move more than this

Number of stories Number of levels below ground Bullding use

Frame m a a n a l Typical floor live load Basic wind velocity Maximum lateral deflcction Design fundamental p e r ~ o d Design accelcrat~on

Earthquake loading Type of structure Foundation conditions Footing type Typical floor Story height Beam span Beam depth Beam spacing Slab Columns Size at ground floor Spacing

Concrete strength Core

Shear walls Thickness at ground flool

McCutcheon Connell Wagner

1991

21 1 m (692 ft)

5 4

3 Office

3-kPa ( 6 0 - p s 0 beams, 4-kPa (80-psf) slabs

5 0 m/s (112 mph) ullimate 100-yr return

100 mm (4 in.), 50-yr rctum 4.2 scc

2.9 mg rms 5-yr return 1% serviceability, 5% ultimate Not applicable

Concrete core, concrete perimeter tube

in lube Mudstone, 2000-kPa (20-tonlfl') capacity Pads to columns, raft to core

3.85 m (12 ft 7 in.) 11.5 m (37 ft 9 in.)

530 mm (21 in.)

3 m ( l 0 it)

120 mm (4.75 in.) on metal deck

65 MPa (10,000 psi) maximum

600 and 200 mm (24 and 8 in.)

rentable) and a large retail development of a funher 60.000 m' (Fig 3.20) The overall dimensions of !he tower are 43.72 by 43.72 m (143 by 143 ft) The tower is 21 1 m (692 ft) above street level and 225 m (738 ft) above the core raR The facade is a glass and aluminum curtain wall

28 Tall Building Floor Systems [Chap 3 ,, Project Descriptions 29

The lower floors consist of steel b u m s spanning from the core to the facade wi

composite concrete slab supported on stoctural steel decking, spanning brtwecn

thick, unpropped

The column spacing at the facade is 6 m (20 ft) A perimeter beam is required to carry the intermediate floor beams This is a 900-mrn-deep by 300-mm-wide (36- by 12-in.), prccasl concrete beam Although this is precast concrete, it is erected in the same way as a sleel beam and as part of the steel frame The use of precast concrete simplifies the fire rating of the slructure at the perimeter where access is difficult It

building regulations The fixings for the curtain wall are cast into lhis beam, resulting

in reliable and accurate positioning

The floor-to-floor height is 3875 mm (12 ft 8.5 in.) for the typical floors The

of 200 mm (8 in.) in height, to be installed by a tenant, providing a minimum 7700-

mm 18-it 10-in.) occuoied soace

~ i v wind resistance stricture for this buildine consists of the core cantileverine ~- "

mately 10% of the wind load on the building, and, more importantly, it convibutes

-

gig 3.11 LOW-rirc floor LE-L14 hl~lbourne Ccnlml

30 Tall Building Floor Systems [Chap 3

significantly to the sway serviceability perromance The remainder of the wind load

is carried by the core element

The central-services core to the building is reinforced concrete from the footings to

unchanged over the full height of the building The 200-mm (8-in.) internal wall thick-

ness is h e optimum to achieve load-carrying capacity, minimal slenderness effects, and

the bottom of the buildine to 250 mm ( 1 0 in.) thick at the buildine too Concrete

encased within the reinforccd concrete column and oermit erection - ~ n i ~ -~ the sirel ~ - - ~ - - frame ~ ~

~ h c rtci'l noor b u ~ n ~ s and rlructural aleel d:cking pcrmils bun-fit in^ from 111c ~ d v a ~ l -

lively cxpun<ive material t l ~ a t is sleel This is iund3menlal lo 3 coniporile steel i n d

The footings to the tower are foundcd in moderately weathered mudstone having a

bearing capacity of 2000 Wa (20 tonlit') The depth of the excavation and the base-

this material The footing lo the core is a 3.2-m (10-it 6-in.)-thick reinforced concrete

raft This extends approximately 2 m (6 ft 6 in.) past the outside face of the core wall

Project Descriptions

MELEOURNE CENTRAL TLOm TO FLOOR OlllENYOl6

r ~ ~ ~ n i nrrm firm

f R ) l , i l O l l P ~ E F ~ O ~ I C A T E O CSE LIR am

O U ~ L D E ~ MI." ELECT m wut~eci

T l t i ~ CAGE m nllil STEEL CDLUNII

ARD LIFI ltim PJIIIIDII-!YITH

32 Tall Building Floor Systems [Chap 3

Luth Headquarters Building

Kuala Lurnpur, Malaysia

Typical floor live load

Basic wind velocity

Maximum lateral deflection

Design fundamental period

2.5 kPa (50 psfl

30 m/s (67 mph) Not available Not eswblished Not established Not established Not applicable Tube in tube Stiff silly clay 1500-mm (5-ft)-diameter bored piles

20 m (60 ft) deep

3.66 m (12 ft)

Typically 640 mm (25 in.) 9degrees radially Precast prelensioned concrete

100 mm (4-in.) precast planks, 50-mm (2-in.) topping

5 by i.2 m (16.4 by 4 ft)

38 m (125 ft) around circumference

32 MPa (5000 psi)

-

The Luth Headquarters Building is a 38-level office building in Kuala Lumpur (Fig

3.23) Of the 38 levels 37 are at or above ground and comprise 7 levels of parking

garage, 2 mechanical-plant levels, and 28 levels of office space

All floors are circular and contain a circular central core However, in elevation the

building is most unusual in that the facade is not vertical but formed from several

solids of revolution The facade of the lowest 22 levels is described by one circular

Project Descriptions

Fig 3.23 Lulh Hcodqunrl~rr Building, Kunin Lurnpur, Mnioysin

36 Tall Building Floor Systems [Chap 3

Tall Building Floor Systems

Fig 3 1 8 Scclion of Lutb Hcndquorters Building

:.,,

7:

, Riverside Center

.,,

3'1 , Brisbane, Australia

Architect Struclunl engineer

Year of completion Height from street to roof Number of stories Number of fevels below ground Building use

Frame mnterial Typical floor live load Basic wind velocity Maximum lateral deflection Design fundamental period Design damping

Earthquake loading Type ofslructure Foundation conditions Footing type

Typical floor Story height Beam span Beam depth Beam spncing Material Slab Columns Size at ground floor Spacing

Tube in tube Rock, 5-MPa (56-todft') capacity Pads to columns, mat to core 3.475 m (1 l f t 5 in.)

12 m (39 ft 4 in.)

600 mm (24 in.) 3.35 m (1 l ft) Posttensioned concrete

125 mm (5 in.) reinforced concrete

1100 by 700 mm (43 by 27 in.) 6.7 m (22 A)

5 0 to 32 MPa (7200 to 4500 psi)

This 39-story 42-level building is a totally reinforced concrete slructure designed as a

"tube in tube" (Fig 3.29) However, because the triangular shape leads to unusually long exterior core wnlls the core has a greater than normal stiffness, and the exterior spandrel beams and columns play only n minor role in the resistance to wind load

Apart from the office building the development includes a two-level basement garage, which covers the site and extends into the Brisbane River The lowest floor is below normal high-tide levels, and the whole basement is designed to continue to function normally during a flood of a height resulting in a head of 6 m (20 11) of water

at the lowest floor The garage is topped by a ground-level plaza, low-rise commercial and retail buildings, and a restaurant which cantilevers 14 m (46 ft) o\,er the river

Tall Building Floor Systems [Chap 3 Project Descriptions

125 SLAB

8601 4W SPANDREL BEAM

POCKETS IN CORE WALL

PRESTRESSING T E N D O N S ~

DUCTS

Fig 3 3 0 Floor plnn; Riverride Cenler

42 Tall Building Floor Systems [Chap 3

The ground conditions comprise hard phyllite a metamorphosed mudstone, which

allowed the use of design bearing pressures of 5000 kPa (50 tunlft') Footings for the

tower are reinforced concrete pads to columns and a raft slab to the core The sur-

rounding basement columns are supported on either pads or piers, depending on the

rock level, which sloped away into the river

p s 0 zone around the perimeter of thc core The use of 4 kPa (80 psi) rather than the

statutory 3 %Pa (60 psf) provides for the more ready accommodation of safes, isolated

slabs span 3.3 m (10.8 ft) and are reinforced with fabric

Floor beams are 600 mm (24 in.) deep nnd 350 mm (14 in.) wide at the soffit

nnchongus The s l h nochornpc> are the m o t econo,nicel and lend tbsmsulrss tu ibt

uss of rm:lll linht incks Tlte circular ducts rdrult in o a r r a ~ e r b d i ~ n s cu~nparcd nlth

the width required ior two flat slab ducts side by side

The partially prcstresscd design provides for a load-balanced condition for about

80% of the weight of the bare concrete This resulted in a flat floor Ultimate load

canacitv was orovided bv additional unlensioned steel Untensioned steel stresses ~ ~ ~,

ucrc limilcd to 130 hlP:, (?1.100 psi) Bcams were designed for lhe same li\c lu:lds 3s

,\I tach end ofth.: btnm t ~ h ~ r l : i t b ~ c o m c s a \\id< 300-mm (I?-i,l ).deep slnb, cnnsid-

suooonine s ~ a n d r e l - beam: the other tendon terminates in a stressing anchorage at the end

uf the 6UO-mm (2-i-in.).dcep rection of the bdnnl This a r n ~ l g e m t ~ ~ o i tendons pr0vtdi.J

Strcssinn was carried out in two stares: 50-c 3 d a \ s niter puurinc ths slnb and

100% after? days These requirements dictated the concrete strength &her than the

minimum design strength specified [The concrete yielded a strength of about 35 MPa

(5000 psi) at 28 days with 25 MPa (3500 psi) having been specified.] A prop load

analysis was curried out, tnking into account the load-relieving effect of the prestress

Plant-room beams support a much heavier load than office floor beams, but the

beam depth and by sloping the floor surface upward from the midspan of the beams

(The slab had to be thicker for ocoustic reasons anyway, and a fall for drainage was

always required, so the structural requirements matched the other requirements.)

The service - ~-~ ~ - ~-~~ care has concrete walls eenerallv 200 mm (8 in.) thick exceot far the

tension in the lowcr rtonc5 occurs under dcsien wind Inads, but in ccncrnl loids ars

comprcssion Concrete was pumped for the full 150-m (492-11) height, with strengths

varying from 40 to 25 MPa (5700 to 3500 psi)

MPa (7100-psi) concrete and 4% reinforccmcnt at the lower levels Some carly prob-

lems were encountered with misplaced bars, which made the placing of spandrel beam

locate the bars the problems disappeared Where bundled bars were used, all column

bars were specified io have splicing sleeves

Melbourne, Australia

Architect Structural engineer Year of completion Height from street to roof Number of stories Number of levels below ground Building use

Frame material

Basic wind velocity Maximum lateral deflcction Design fundamental period Design acceleration Design damping Earthquake loading Type of structure Foundation condttions

F o ~ t i n g type Typical floor Story height Beam span Beam depth Beam spacing Material Slabs Columns Size at ground floor Spacing

Concrete strength Core

Thlchness at ground floor Concrete svength

Reinforced concrete core and perimeter frame tube-in-tube

Highly weathcrcd siltstone Pads to columns, raft to core

3.7 m (12 it 2 in.) 10.8 m (35 f t 5 in.)

400 mm (16 in.) 4.6 m (15 ft) Posuensioned concrete 125-mm (5-in.) reinforced concrete

1 I00 mm (43 in.) square 8.1 m (26 ft 6 in.)

60 MPn (8500 psi) maximum Slip-formed shear walls

400 and 200 mm (16 and a n )

60 MPa (8500 psi) maximum The Bourke Place project includes a lower structure with 5 4 floors above Bourke Street in the city of Melbourne (Fig 3.31) On top of the concrete tower is a steel-

tower rising to approximately 255 m (837 ft) above the street Alongside the tower there are an 8-storv narkine raraee (four of which are below eround) and olazas with , - - b ,

rood and retail areas The total leasable floor space in the office tower i s approxi- mately 60,500 m' (651.200 ft')

The tower structure consists of a slip-formed reinforced concrete core, postten-

44 Tall Building Floor Systems [Chap 3 Project Descriptions 45

and 3.33) The core structure is approximately 20 m (66 ft) square at the base Most

internal walls are 200 mm (8 in.) thick with some 150 mm (6 in.) and remain con-

stant for the full height of the structure The external wails vary from primarily 400

mm (16 in.) thick at the base using 60-MPa (8500-psi) concrete to 200 mm (8 in.) lor

the top 15 slories, requiring only 25-MPa (3500-psi) concrete [40 MPa (5500 psi) was

used for pumpability.]

(Plioro by Srjl~irc Plio!ogropi!ic.r.)

Fig 3.32 Typical tower floor plon; Bourke Place

? O R ivn,oxn ,m

"liiiill ilC DiiYI*i

Fig 3 3 3 Typicill n o o r profile, ~ o u r k e ~ i u c c

46 Tall Building Floor Systems [Chap 3

MPa (5500-psi) concrete was used, represented an effective extra ovcmll capitalized

cost to the client of approximately $;100,000 (Australian) per floor

Two substantial core shape changes occur up in the tower as elevator shafts that

the changes in wall thickness were positioned sufficiently high up in the tower to

ensure that the cote aould be off the construction crilical path in order to avoid any

time delays The design of the slip form incorporated the facility to reduce the wall

thickness and to "drop off' these portions Cost comparisons during the design dcvel-

opment phase indicated that slip forming was the most cost-efiicient method of con-

A t the tilne of dcs~gn, building rcgulations lor fire prolcc~inn required 1h3t spandrel

t2nce lo brnd In3d5 on lhc slnlcturc Tnr h e ~ m s ucr? designed for l l ~ c dead and livc

load requircmcnts: then their capacity to resist additional wind load was assessed This

amounkd to approximately 7.5% ofthe total wind load on the structure, meaning that

the core need only be designed for 92.5% rather than the full wind load The "core and

partial-frame" approach represented significanl cost savings to the client

A 125-mm (5-in.) normally reinforced concrete slab spans between 10.8-m (35.4-

it)-long band beams at typically 4.6-rn (15-it) centers The band beams radiate out

from the core and are typically 400 mm (16 in.) deep, but are notchcd at each end to

ducts, and they enable the total floor-lo-floor height to be minimized This represents

savings to the client as the overall height of the building can be reduced without

aflectine, the number of Floors

The band beams are posttensioned from underneath, utilizing the vertical face of

the notches This separates the posttensioning contractors from the "work hce."

poured floor nnd it r l i m i ~ ~ a ~ e s ihc n<<d Tor reccsssd pockets in the flour surlace

T11c b ~ i l d c r used three seu oll;!ble fonns which "lclpfrog~ud" up tllc structure and

riun or pouring one q u l i d r ~ n ~ wcry dzy To sssist in mli~ntninlng his &day cycle, col-

c;11cd

Tllc floor! ~ V C T ~ c11~~kcd 10 CnsUrL: 111.11 ~lnder llle l l l ~ s l f a v ~ r ~ b l ~ c~r~umsliinces 110

working dnys were acllieved

Project Descriptions

Central Plaza One Brisbane, Australia

Architect Suuctural engineer Year of completion Height from sveet to roof Number of stories Number of levels below ground Building use

Frame material Typical floor live load Basic wind velocity Maximum lateral deflection Design fundamental period Design acceleration Earthquake loading Type of structure Foundation conditions Footing type

Typical floor Story height Slab Columns Size at ground floor Spacing

Spread footings, anchored perimeter wall

3.66 m (12 ft) 10-m (33-ft)-span posttensioned 275 mm (10.8 in.) thick

1200 by 1000 mm (47 by 39 in.)

7 m (23 fl)

5 0 MPa (7100 psi)

-

Central Plaza One is currently Brisbane's tallest building with a total o f 4 8 levels and has a total height of approximately 174 m (571 ft) above sveet level (Flg 3.34) The building features a four-story avium with an internal running stream and land- scaping at the ground-floor level and a four-level basement garage A distinctive roof

(8 ft) of the roof structure makes the building unique among modem high-rise build- ings in Australia The tower houses three plant rooms at levels 4.26 and 41

A six-story office block adjacent to the main tower has banking facilities at the ground-floor level and shares the common basement structure with the tower ThlS

"hank annex" incorporntes an additional plant room nt level 5

Tall Building Floor Systems The tower structure comprises a reinforced concrete core and frame with postten-

Design requirements were as follows:

beams to central core

Floors to be designed to allow for maximum flexibility in locating penetrations for

services

within acceptable human response lirnitotions

Project Descriptions

allow for joint design at critical locations in the curtain-wall system

that the tower would be wind-sensitive and accelerations could b e excessive The sim- plified model comprised the central core as a cantilever linked to the outer frames, with axially stiff linkages representing the floors the entire assemblage being consid- ered as a plane frame Having gained considerable insight into the behavior of the structure from the preliminary analysis, the tube-in-tube structural system was chosen for resistance to lateral wind loads

During the preliminary design stage a l:400 aeroelastic model was being devel- oped and tested in a wind tunnel to d e t e d n e and minimize wind pressures by varying the dvnamic earnmeters Considerable analytical work was carried out to tune the

I ,- .- -~

ations under \vind 1o;ading were brlou acceptable Ie\,cls In lhc analysis for core-frame

diaphragm action of the floor slabs Propping of the structure'at the ground floor a i d basements avoided the problem of having Lo deal with large momens at the core fool-

i

The cenval core occupies a space approximately 16 m (52.5 ft) square in the center

of the building and is, in reality, two cores with an elevator foyer space between The two cores are linked together via floor slabs and beams, and in addition, by large diaphragms in the atrium and plant rooms The atrium diaphragms were found to be particularly effective in reducing deflections by giving the building an exceptionally

The central core is a multiccll reinforced concrete structure with wall thicknesses

in the lower parts of the building to 0.5% at the top The core was designed globally for biaxial bending and axial load using the program FAILSAFE In this program a particular section of the core is defined as an assembly of square elements within a system of coordinates, and the quantity and location of steel is also defined within the coordinate system The program outputs a failure surface for axial load versus moment

concrete theory, as appropriate for the element under consideration

except that two special effects required particular attention in the design and detailing

joints, both on lhc dm\r!ng board :!nd on rltc during cnnstruction

50 Tall Building Floor Systems [Chap 3

The ground-floor slab was designed in reinforced concrete, incorpomting an exten-

sive beam system At this level the wind-propping loads were considerably higher

than in the basement slabs, and in addition the slab was designed to support a 10-Wa

room slab over the ~ ~ atn'ltrn

The ground-floor slab is a multilevel slab with sloping and stepped purtions, and in

the nonheast comer it contained large openings Special bands of heavy reinforcing

diagonal band of heavy steel from the core to the northwest corner of the site was

required lo ensure a load path to compensate for the large penetrations o f t h e nonheast

corner

Tower floors were designed as posuensioned flat plates spanning approximately 10

m (33 ft) from the spandrel beams to the cenval core Typical floor slabs are 275 mm

five 12.7-mm (0.5-in.)-diameter supergrade strands in 90-mm (3.5-in.)-wide ducts

The banded tendon arrangement provides maximum flexibility of floor layout for the

positioning of penebations for services and internal stairs in the tenancy design stage

The flat-plate soffit was important in allowing the builder to speed up the form-

work placing and in achieving the specified cycle times Posttensioning also meant

minlmum passive reinforcement, another feature to assist thc builder

Finite-elemcnt analysis of the floor slab indicated the existence of high shear

slresses near the comers of the core This was dealt with by installing some shcar stccl

which were posttensioned to minimize deflections

Kilmirrer 1983 Design and ConnnlcIia,r offl~e Lull? Heodqaunrrs Buiidirtg, K ~ o i o Lu,npur

Monin 1989, lVirzd Design ofFourBuiidirtgr up to 306 ,n TO!!

Lateral Load Resisting Systems

Two fundamental loteral force resisting systcms are the braced frame (also kno\\'n as

frame) Thesc systems evolved during the beginning of high-rise construction in the

twentieth century Braced framcs and momcnl resisting frames are normally orga-

frame system Thc two systems may be used together as an overall interactive SySlem

commonly used today as effective means of resisting lateral forces in high-rise con- struction ior buildings of up to 40 or 5 0 stories

,

1 !.,

Braced framcs arc cantilevered vertical trusses resisting lateral loads primarily through

I ' ? the mial stiffness of the frame members Axial shortening and elongallon of the column

tion lor slender truss systcms The effecriveness of the system, as characterized by a

low- to midhcight range

axcs of all mcmbcrs intersect at a point such that the member forces are axial CBFs

shcar into the frame, which lowers the stiffness-to-weight ratio but increases ducttl~ty

52 Lateral Load Resisting Systems [Chap 4

lransfer path as they absorb a ponion of the column load in proportion to their stiffness

This creates additional forccs in both diagonal and horizontal members of X-bracing

T o accommodate door and other openings, EBFs are commonly used, a s shown in

ductility Higher ductility through inelastic shear or bending action of the link beam

make it a desirable lateral system in areas of high seismic activity Ductility is measured

by a well-behaved hysteresis loop and achieved through proper connection and member

design such that all modes of instabilities and brittle failures are eliminated

Braced frames are most often made from structural steel because of ease of con-

struction Depending on the diagonal force, length, required stiffness, and clearances

the diagonal member in structural steel can be made of double angles, channels, tees

tubes, o r wide-flange shapes Besides performance the shape of the diagonal is often

based on connection considerations Examples of typical braced frame connections are

buildings, where frame diagonals may be enclosed within permanent walls Braced

frames can be joined to form closed section cells, which logetherare effective in resist-

ing torsional forces These cells may be bundled to take advantage of additional stiff-

Fig 4.1 Concentric br;lrcd

thus sensitive lo the lootprtnt of ihe core area and the arrangement 01 the clcvators When ihe slenderness ratio of a core truss (the ratio of truss height lo le2rt u,idth) In-

and uolifr forces of chord columns While truss chord members may rr3dily be drsigned

forces, net foundation uplift forces are generally &desirable A design

be lo spread Lhe chords as far apart as possible while diverting gravity load to these chords to Drevent or reduce the net tensile force

As slenderness increases the a i a l drformalions of lllc chord columns o f a truss sys- tem become more critical in controlling the sway of the slructurc Increasing the r l ~ l f - nrss and strsnath of lhe chord members in proponion lo the work done by those mem- bers will prov%e an effective way to minimiz; sway The bracing system between the

eliminated or minimized in size and the efficiency of the boundary chords maximized

T o further reduce the steel tonnage and cost of the structure, composite steel and con- crete chord columns may be utilized Using concrete in chord columns will most likely provide a lower unit price for strength and axial stiffness

.,

nected together in a planar grid form which resists lateral loads primarily through the flexural stiffness of the members Typical deformations of tha moment resisting frame system under lateral load are indicated in Fig 4.4 A point of contraflcxure is normally located near the midheight of the columns and midspan of the besms The lateral defor- mation of the frame is due partly to the frame racking, which might be called shear sway, and partly to column shortening The shear-sway camponen1 constitutes approx-

tion of deformation is due to column shortening (cantilever component or so-called chord drift)

5traint ~~~ ~~ on the olannine module ~ h ; u frame mav be architecturallv exposed to express the

c ~ n match !hat required fur grnvity lraming In lac1 ths stecl u e ~ g h t - ~ prenlium for iatual frame resistance decreases with increasing gravity londs on the frame

5 4 Lateral Load Resisting Systems [Chap

(a)

Fig 4.3 Typicul corlncrlion debiir lo) CUF (b) EUF

sect 4.11 Braced Frame and Moment Resisting Frame Systems

58 Lateral Load Resisting Systems [Chap 4

volves a transfer of shear forces from the top to the bottom of the building Figure 4.7

shows the truss and frame deflections if each resisted the full wind shear The distrihu-

tion of wind shear between lruss and frame can also be noted Frame-truss interacting

appropriately manipulated Optimum efficiency is obtained when gravity-designed

then combined with gravity-designed exterior columns and spandrel beams with rigid

SEMIRIGID

WELDED CONNECTION

RIGID CONNECTION

SHOP WELDEDIFIELD BOLTED

WITH COVER PLATES

RIGID CONNECTION SHOP WELDEDIFIELD BOLTED

WITH END PLATES

I J sect 4.7, Braced Frame an Moment Resisting Frame *terns 59

3~

connections If the lateral stiffness of the system is adequate, this then would ~ r o d u c e

nents The frame beam spans, story heighls, and core uuss depth are key parametcrs Tension or uplift conditions may limit the possibility of increasing chord columns