Structural System for Tall Buildings

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Structural syst.erns for ~ a l l ~ u i l d i n g s

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Council on Tall Buildings and Urban Habitat Canlribulon S p o n s o r i n g Soclellcr Internntlonul Asrocintion for Bridge and 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) Inernalional 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 Dcsignen ( I R ) The following identifier those firms m d orgmiwtionr who provide fartheCouncil's financivl s u p p o h Patrons A1 Rnyes Group. Kuwait Consolidnted C o n t m a o r r Internulional Co.. Athens Dnr Al-Hnndnsah '.Shnir & Panncrr." Amman D L F Univcrsnl Limited. Ncw Dclhi Zuhair Fnyez & Arrociales. Jeddvh Juros. B n i m & Bolles. N e w York Kuwait Foundmion for the Advonccmcnt of Sciences. Kuwait Shimizu Corpondon. Tokyo T h e T u r n e r Corpomtion. New Yark

Sponsors Europrofilc Tecom. Luxembourg Gcorge A. Fuller Co.. New York T.R. Hnmrah & Yeung Sdn. Bhd.. Sclangor HL-Technik A.G.. Munich Hong Kong Lnnd Group Lld.. Hong Kong Kone Elevators. Helsinki John A. Mnnin & Aaroc.. Inc.. L o r Angelcr Ahmad Mohnrrom. Cairo Walter P. Moore & Associates. Inc.. Hourton Nippon Slcel. Tokyo Otis E l e w l o r Co.. Forminglan O v e A m p Pmnerrhip. London P D M Strocnl Inc.. Slockton Leslie E. R o b c m o n Associatea. New York Snmrung Engineering Br Conrtruction Co. Lrd..Seoul Snud Consult, Riyadh Schindlcr Elevntor Corp.. Morrislown Siecor Corporntion. Hickory Tukenako Corporation, Tokyo Tishmon Conslruction Corporarion of N c w York, New York Tiihman Speyer Properties. Ncw York W c i r k o p i & Pickwonh. N e w York Wing T a i Conrtmction &Engineering. Hong Kong Wong & Ouynng (HK) Lld.. Hong Kong Donor5 American Bridge Co.. Pittsburgh American Iron and Slcel Institute. \Vushington, D.C. W.R. Grncc & Comp;my. Cambridge Hnscko Corporaion. Tokyo T h c Herrick Corp.. Pleasnnton Hollundsche Belon Mnnlschappij BV, Rijswijk Hong Kong Housing Autl~orily.Hong Kong lffland Kivvnvgh Waterbury. P.C.. New York

O'Brien-Kreilrbcrg & A S T O C ~ ~ ~In=.. ~CI. Pennrlukcn R T K L Associates. Inc.. Bnltimore Skidmore. Ou,ingr & hlerrill. Chicogo Steen Con~ultuntrPty. Ltd., Singspore Syiko & Hcnnery. lnc.. New York nornton-TomorcuilEngineer5. Ncw York Werner Vosr & Ponncrr. Braunrchwcig Wong Hobach Luu Consulting Engineers. La5 Angcles

Office o f Irwin G. Cwlor. P.C., N e w York H.K. Cheng & Pnrtnen Ltd. Hung Kong Douglas Specinlist C o n u n c t o n Ltd.. Aldridgc H n n Conrulwnt Grnup. Snntn Monica The G c o r g ~Hymnn ConsWclion Co.. Balhrsdn Ingenicurburo Mullcr Mnrl GmbH. Mnrl Institute Sulwn lrknndnr. Johor INTEMAC. Madrid J H S C o n s w e n o e Plnncjnmento Ltd.. Sno Pnulo Johnson Fain a n d Perrim Asroc.. Los Angeler T h e Kling-Lindquist P m c n h i p . Inc. Philadclphio LeMessurier Conrultnntr Inc.. Cnmbridge

L i m ConsulU~tts.Inc.. Cambridge Meinhnrdt Auslrnlin Pty. Ltd.. Melbourne Mclnhnrdl (HK) Ltd.. Hong Kong Mucrer Rutledge Consulting Engincen. N e w York Oboynshi Corpomtion. T o k y o O T E P In~crnntional.SA. Mndrid Charles Ponkow Builders. Inc.. Alwdenn Projcst S A Emprecndimentos e Servicos Tecnlcos. Rin d c Jnncim P S M Inlernnllonnl. Chicago Skilling Ward Megnurson B n r b h i r c Inc.. Senltlc Tooley & Company. L a s Angcles Nobih Yourref and Arrocinlcr. Los Angelcs

C o n t r i b u t i n g Pnrtlclponlr Advnnccd Slructuml Concrplr. Danvcr Advicrburnu Voor Bouwwchnick BV. Amhcm Amcrirnn lwti~uteof Slecl Con.uu~Lion. Chicago Anglo Amcricnn Pmpcny Scrviccr (Ply1 Lld.. lohnn"&burg Archituaml Scrviccr Dcpl.. Hong Kong Alelici D'Architcctum, dc Genvnl, Genvnl ~uslnlinnlnstitulc olSlccl Conrwcdon, hlllronr Poinl B.C.V. . Pmnctti Miiono ~ S.r.1.. ~ ~ 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 cWind ur Tunnci ~ Labornlory d ~(U. Wcrrcm 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 Lbonlor). 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 ~ Arlrlnc ~ ~ g l n r r~nn~r scatllc ~. . Fujilnva lohns~non1 A s ~ o c i l r rCnlcagn . 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~xAr$ocialcr. Lo, Anerlcr I l r ~ l l l ~Buildtng$ ) lnlrrn:l8vnll In:. F ~ i d r i l l ~ l t m ~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

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~ 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 mCons Engrr.. PC. llru York E- m~, r n Rod, & Sons lnd. lnc.. New Yoik Rovon Woll8~mrD l r t r l & lruin 1°C. Gurlph ScpllotSaio rcmnding (Sdnl Bhd, K ~ o l oLumpur scrrrn S m : m r Gimi5 dc Encrnhon~S A . Rlo dc lnncim Scvcmd Asrociacr Conr. Engn.. New York SOBRENCO. S.A.. Rio dr Inncim south Africnn lnrtiatc of Srccl Conslrucdon. Johmncrbvrg 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.crA?ro:irlrl. Nrw Yorl wond~.,d.cl,dc Con~.lurn,. ~ r rYolk .

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 Tall Buildings Council on Tall Buildings and Urban Habitat Committee 3

CONTRIBUTORS I.D. Berzrretf~ Joseph Bicnls Brian Coviil P.H. D a y o ~ ~ ~ n r ~ s a Eiji Frrk!ria~ro him B, Ki1,rzister Rpscard M. I;o~~,aicz)k Owerr bJanin Il'iliion! Afuibortnie Sciichi Ml,ra?lrofsll % Okoshi AR,r~adRolrirnian 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. D.C. Auckland Bogoti Lisbon London Madrid MexicoClty Milan Montreal New Delhi San Juan Singapore sydney Tokyo Toronto

New York San Francisco Washington. Caracas

ACKNOWLEDGMENT OF CONTRIBUTIONS This Monognph uar prepxed h j Commillcc 3 (Slmctuml Syrtcm5)of ihc Council onToll Buitdlngr and Urban Hnbitnt nr p ~ onf the Tali Building, and Urban Environment Series. Thc edtlonll gmup $bas R)szxd hf. Kowatcz)k, chairman; Rohen Sinn, ricc-chnirmln; and hlox B. Kiimister, editor.

Foreword

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

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

Project Dercriptionr were conuibuted by:

The 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

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. Bychenkov. 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 Kavyrchine. Mnn B. Kiimirler (editor). GcnF. Konig. Ryszwd M. KowaIczyk (chairman). Juraj Korak. Monsieur G. Lacombe. Siegfried Liphardl. Miguel A. Mneiar-Rendon. Owen Mnrrin. Jaime Mnson. 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

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 Crireriofor 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~nenfseries, 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 committee 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 committee'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 Singapore. This unique international survey examines the myriad o f archirecturni. engineering, 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 indusuialized world. inherent human desire to build skyward is nearly as old as human civilizntion. The ancient ovramids of Giza in Eevot, the Mavan temdes in Tikal. Guatain lndia arcjust a-fiw erampl& eternaily benring witness to mala, and the Kuwb this instincL Skyscrapers in thc modcrn sense began to appear over a century ago; however, it was nnly after World War I1 that rapid urbani'ration and population growth created the need for the conswction of tall buildings. T h e dominant impact of Llll buildings on urban landscapes has tended to invite contrnvenv. o~ticularl; in cities with older historic structuris. The skvscraoer silhouette has transformed andshaped the skylines of many cities, thercby creGing ;he most cbrracteristic and symbolic lrstaments to thc cities' wealth and their inhabitants' collecti!,e

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The ordinary observer recognizes the tall building primarily with respect to its exterior architectural enclosure. This is nnly natural, as when we consider the great pyramids of -~ Eevot -, our overridine imaee is bf their characteristic sharre. It is o d v re&ntlv that we have begun to realize the creativity and colossal effnn expended by these ancient 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 svstems are crucial in defining the architectural expression and in placing the tower within 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: their evo~utinn~anh historical development as well as the variety of solutions engendered to allow the tower to be realized safely andcfliciently. As in the pas!, new nchievoments .in material science.. comouter-aided desien. and construction technology -. have opened 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 oftin mav,have a drnmatic imoact on the architectural design. - The intent of this volume is lo demonstrate the chmcteristic features of many outstanding syslem form5 while documenting the faclors leading lo their selection for projects aclually realized. The swctural systems for high-rise buildings are constantly evolving and at no time 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 it is worthwhile to present the current state of the M while being aware that progress in svstems develooment is oneoine. The planning for thts Monograph began soon after the decision u,nc made by the Council to expand the chapters of the original Monograph into separate volumes. The concept of a volume based-on a survey of some of the most innovative examples of tall building swctural systems conuibuted by leading engineers and design firms of the

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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 structural design of the buildings included herdin. The surveys were initiated and the re. s ~ o n s e cs o m ~ i l e dbv Max filmister. This material reoresen& the core of the comoleled dook and the.vast mijority of the work. Bob Sinn then'assembled all of the "looseknds" of the compilation in the summer of 1993 in order to finish the completed volume in time for publication. The ~ o n o g r a as ~ ha uhole is a product of extensive lenmtr,ork. Sincere thanks go to all ofthc conuibutors who offered their valuablc time to share thew cxperirncc with the readers. It Is around this information that the cnurc uork is construc[ed. W e hope that the information included may be presented lo a broad professional audience. This exchange of information is one of the tenets of the Council and is in fact a condition for progress in the design of tall buildings. Supporting information for Chapter 5 from Drs. B. 1. Vickery. 1. D. Holmes. and J. C. K. Cheung is gratefully acknowledged, as is the Australian Research Grants Commission for its suppon of the fundamental research. As mentioned, we are aware that everyday Progress is made in the field of structurnl engineering for high-rise buildings. Thc comn~itlceis already thinking about expmdlng and updating this \,olume. \\'c urge all readers lo enrich and complement thia rrrrrk by writing the Council or ioining the commitke. ~ i n ~ ~wcl lwould ~ . like lochpress our appruui;!lion to Dr. Lynn Beedle, ulto encouraged us to prepare this work and \rho ad\,ised and aupponed tltc efiori. \\'e dudicall: this book to him.

Robert Sirm Vice-Cltoimmn

Mar B. Kilmisrer Editor

Contents

1. Introduction 1.1. Condensed Rererenccs/Bibliography

2. Classification of Tall Building S t r u c t u r a l S y s t e m s 2.1. Condenrcd RererenceJBibliogmphy

3. Tall Building Floor S y s t e m s 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 3.3. Condensed RefercncerlBibliogmphy

4.. Lateral Load Resisting S y s t e m s 4.1. Bnced Frnme and MomentRc;isting Frnme Sysrems Project Derertptions S~nwnBank ACTTower Kobc Portopin Hole1 Nanhi South Tower Hotel World Tmde Center KobeCommercc. Indusuy and Trade Centcr Mvrriott M q u i r Hotel Taj Mnhnl Hotel Tokyo Marine Building Knmognwn Grand Tower Shear Wall Syrlemr Project Dc.cipUonr Mcmpolitnn Tower Embassy Suites Hotel Singapore Treasury Building 77 Wcrt Wuckcr Drive Casielden Ploce Twin 21 Majestic Building Telecorn Corporate Building

Contents Core nnd Outrigger Systems Project Daeriptions Cityspire Chifley Tower One Liberly Place 17 Smle Sueel Figuema at Wilrhlm Four Allen Center Tmmp Tower Woterfmnt Place Two Pmdentinl Plnw 1999 Bmadwvy CilibnnkPloro 4.4. Tubulorsyslemr P r o j s l Descriptions: Frnmed Tuber Amoco Building 181 West Madiron Sueet AT&T Corpamte Cenler Georgia Pacific 450 Lexington Avenue Mcllon Bank Sumitorno Life Insumnce Building Dewcy SquoreTou'er Monon international Nations Bank Coipante Center Bvnk One Center Cenml Ploro Hopewcll Ccnuc Project Descriptions: T-cd Tuber F m l Inlemationol Building Onteric Center John Hancock Ccnter 780 Third Avenue Holel de las h e r PI'ojffL Dereriptions: Bundled Tuber Sears Tower Rinlto Building N6E Building Cnmegie Hall Tower Allied BonkPloro 45. Hybrid Systems PmjeclDiscriptions Ovcrreos Union Bonk Cenler Citicorp Ccnrer CcnTmrusl Center Columbia Seafirst Center First Bnnk Place Two Union Squorc Fist Intersmte World Center Hong Kong Bank Headqumers 4.6. Condensed ReierencesiBibliogmphy 4.3.

5. Special Topics 5.1.

Designing lo Reduce Perceptible Wind-Induced Motions

5 2 Fire Prolection of Swctunl Elements 5.3.

Condensed RcfemnccdBibliognphy

Contents

6. Systems for the Future 6.1. 6.2. 6.3.

6.4.

A~hiEhilecedTendencies Slructural Tendencies Other Tendencies Project Descriptions Miglin-Beiller Tower Deurbom Ccnter Bnnkof thc SouthwertTowcr Shimiru Super High Rise Condensed RclerenceslBibliogmphy

Current Ouestions, Problems, and Research Needs Nomenclature Glorrury Symbols Abbreviudonr Units

Contributors Building lndex Name lndex

Subject lndex

Structural Systems for Tall Buildings

Introduction

Smctural system 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 publication of the initial Council Monograph Tnll Building Systems and Concepts in 1980. international style and modernist high-rise designs, chanclerized by prismalic, repctilive 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 architectural aesthetic. Innovntive swctural systems involving megaframes, interior superdiagonally braced h m e s , hybrid steel and high-strength concrete core and outrigger systems, artificially damped structures, and spine structures nre among the compositions 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 exciting and unique forms for today's tall building structures into the overall tall building system hierarchy. 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 that rather than being a collection of papers or a general survey of tall building structural systems, the Monogmph would be organized with respect to such a database-type format of structural and . oroiect . information on actual buildine-.oroiecu. The committee thererore requested detailed informarion from engineers in Lhe profession, regarding the structural design of some: of the most innovative high-rise projecrq throughout the world. An enthusiastic resoonse from the s l ~ ~ c t u r eneineerine nl communirvoro.. 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 &k. These compr;hensive data &e [he p r i m 5 focus of this ~ o n n ~ r n pand h should

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[Chap. 1

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Chap. 11

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 classification 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 evaluated. Tall building floor systems arc discussed in Chapter 3, which includes recent

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Rg. 1.3 NBC TOCC~, Chicago. Illinois, Cumplclcd 1991. (Cauncry: Skidruorr O t ~ i n ~S sblerriil.1

3

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Introduction

4

[Chap. 1 : , , .,

developments in posttensioned concrete floor systems for high-rise construction in Australia. Structunl systems for tall buildings have historically been grouped with respect to their ability to resist lateral loads effectively. Therefore Chapter 4. "Lateral Load Resisting Systems." forms the core of the work, with system descriptions for nver 50 The oroiects are arraneed within five basic subclassifications for lat- - oroiects. r~ era1 load resistance with generally increasing efficiency and application for taller buildines: braced frame and moment resisting frame systems, shear wall systems, core and ouGigger systems, tubular systems, anhhybrid systems. Each subsection is preceded 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.

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Classification of Tall Building Structural Systems

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1.1 CONDENSED REFERENCES/BIBLIOGRAPHY 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 project: "A building whose height creates different conditions in the desieo, construction. of a cenain reeionand oeriod." For and use than those that exisi in common buildines u 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. The ~roeressionofiateral load resisiineichemes from eiemental beam and column assemblages toward the notion of an equivalent vertical cantilever is fundamental to 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 (Fig. 2.1). At one end of the spectrum are the moment resisting frames, which are efficient 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 systems were placed with the idea that the application of any panicular form is economical 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: b

.

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

. .

[Chap. 2

Classification of Structural Systems

6

Chap. 21

7

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 achieve a comprehensive worldwide survey of the performonce of buildings in the 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 independent. 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 premium for resisting lateral loads. Some degree of independence is generally recognized between thefloor fmnzing sjsrr,t!s and the loferal load rerisring qsrenzs, although the integration of these subassemblies into the overall structural organization is crucial.

Trusses Foundations Lateral load resisting systems Walls Frames Trusses Diaphragms Type and magnitude of lateral loads

~~~

Wind Seismic Strcngth and serviceability rcquirements Drift Acceleration Ductility

~

I

LEVEL A Framing systems

LEVEL B

I

In 1984 the Council attempted to develop a rigorous methodology for the cataloging 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

I

framing subsystems (XX)

/

Building configuration and load transfer (XX YY 2)

Elevation TYPE I

I

TYPE 11

I I

TYPE Ill

1)

TYPE IV

Fig. 2.1 Cornpurironof rlruelurol syetcmr. (CTDUH, CrortpSC. 1980.1

I

Fig. 2.2

Clvrrilicoliun of rlrurlurul syrlernr. (Folnl,ler rrnd Beedlr. 1984.1

I

8

Classification of Structural Systems

[Chap. 2

This Monograph therefore divides the discuss~onof tall bu~ldtngsmctural Systems into the subsystems mentioned.

3

1 I

Tall Building Floor Systems

2.1 CONDENSED REFERENCES/BBLIOGRAPHY Falconer and Beedlc 1984. Clarrlficnr!on of Toll Bulldlng S),srem. Khnn 1966, oprlmtzo~lonO ~ B U LS:rucrurer I ~ ~ ~

3.1 COMPOSITE STEEL FLOOR SYSTEMS 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 stiuctural depths and consequent efficient use of interstitial ceiline soace. and 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 slab. n e . o r a metal steel deck, either composite or noncomposite (Fig. 3.i). When a composite floor framing membcr is combined with a composite metal deck and a concrete floor slab, an e x ~ c m e l yeff~cientsystem is formed. The composite action of the beam or truss elcmen1 is due to shear studs welded directly through the metal deck, whereas the composite 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 com~ositebeams mav be formed either bv com~letelvencasine 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 was - shear c&nectors (Fie. . - 3.1). The concrete-encased comoosite steelienm common prior lo the dcvclopment of sprayed-on ccmentitious and board or ball type fireproofing materials, which economically replaced the henvy formed concrete insun found in composite lation on the steel beam. Todny the m o s ~ c o ~ m onrrangemmt

.

~~

9

~~~

~~

~

Tall Building Floor Systems

10

[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 orienled parallel or perpendicular lo the compo>ite beam span and may ilself be either comoosite or noncomnosilr (form deck). . F i-~ u r c3 ? shows a typical .. office building floor that is framed in composite steel beams. ~~

Sect. 3.11

Cornposits Steel Floor Systems

11

In composite beam design. h e stress distribution at working loads across the comnosite section is shown schematicallv in Fie. 3.3. As the tor, . flanee of h e steel section is normally quite near h e neutral axis and consequently lightly stressed, a number of builtup 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 been used. Also, built-up composire beam schemes or tnpered flange beams are possible. In all of these cases. however. the increased fabrication costs must be evaluated which lend lo offset the rclalivt: malerial efficiency. In addition. a rcl3tively wide and thickgauge top flange must be provided for proprr and rffr.cli$,e shex slud isslallalion. A n"smat& comnosik steel beam h& two fundamental disadvantapes - over other 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-

-

COMPOSITE BEAM FlAT

wm

MFFlrRElNFORCW CONCRETESLAB

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

COMPOSEBEAM W m MEFALOECK A N 0 CONCRETESLAB

C O M P O S E BEAM wrm METAL DECK A N 0 CONCRETE SLAB (RIBS PEAPENDICUldR~

(RIBS PABALLEL)

Fig. 3.1 Comporite benm sjstems.

WORKING LOADS

ULTIMATE LOAD

Fig. 3.3 Composite beam stress dirlribution.

I Tall Building Floor Systems

12

[Chap. 3

pons, and (2) building-serviccs ductwork and piptng must pass beneath the beam, or the beam must be provided with web penc~rattons(normally reinforced with plates or ancles leadinc to hirher fabricatton costs) to allow access for this csui~ment For this . 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 members 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 consequent construction cost premiums.

-

u

-

.

:>,i;~

j ,. ,:,: . ~

Sect. 3.11

Composite Steel Floor Systems

13

Succc$si~llcnmpnwte hc:m ile.;ign T'LII.IIL.\ the c~nsideri~tio~t ni \.ilriol~ rerulls ill relat i t c h lot. !ihralion :~!#,t>litndrc irnm 1r.losilory hcel-dlop d ~ ~ i l : l t ~ oand n s 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 . .vibrations 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~,andthe structure itself are used in conjunctiott with htate-of-thc-;lrt prediction tllodels to evalue~ethc potential for pcrceptible noor i~ibrations.

-.

2

Composite J o i s t s and Trusses

.

.

.

.

Preeneinccred nronrictnrv oncn-web lloor ioists. ioisl -rirders. and fabricated noor = trusses are viable composite memhcrs when combined with a concrete noor slab. The advanta~esof an opetl-wcb nour framing 5ystcm include increnscd spannabilily and stiffnus;due to 1he.decocr s~ructuralden& =ncl case in nccomrnodatine- electrical conduit. plumbing pipes. and heating and air-condilioninp ductwork. Open web systems do, however. carry :I picmiuln for itreprunling thc many. rcla~ivelyihin, components of ~

~

............................................................ 1 bc:;'TAPERED ;~ .-, . ; .-., C5ZJ -J?C: .... .. - L..

....... ....?..........-....................... .*.,

HYBRID C0MPOSITEBEb.M

..

BUILT-UP COMPOSm BEAM

..

-..,. ......................... .......................... ?

.... . . ' ,'I. "

,. C ,.i

,

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:'

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6

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0

0

,.$"

0

A

SECTION

(4 Fig. 4.12

Dctililr o f prcrort rnncrclc pnnel: Scnwn Bunk. (Conrir#ucdl

67

68

Lateral Load Resisting Systems

[Chap. 4

ACT Tower

Structural engineer Year of completion Height from street 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 Dcsign damping Earthquake loading Type of structure Foundation conditions Footing type Typical floor Story height Beam span Beam depth Beam spacing Slab Columns Sire at ground floor Spacing Corc

Braced Frame and Moment Resisting Frame Systems

I

3. A dynamic test to check the dynamic analysis results

Hamarnatsu City, Japan

Architect

Sect. 4.11

Nihon Sekkci Inc. and Mitsubishi Estate Co. Ltd. Nihon Sekkei Inc. 1994 21 1.9 m (695 ft) 47

Hotel, offices, retail space Steel 5 kPa (100 psfJ 30 mlsec (67 mph) Hl2OO. 100-yr return period wind 4.52.4.73 sec 52 mg peak. 100-yr return period 1% serviceability. 2% ultimate C = 0.06 Braced frames Clay, sand, and gravel Piles 1.5 to 2.4 m (5 lo 8 ft) in diameter. 25 to 30 m (82 to 98 it) long

The dynamic annllsis war performed using the mean and the standard dc\'iarion as well as the power spectruln of the ovrnurning moment and the torsional moment cocicienls obiined inthe wind force test i The building response specva are obtained by combining the wind spectra (for the x, y, and 8 directions) and the magnification factors versus frequency curve. As the building cross section is ellipsoidal, special consideration was given to getting the maximum response values used in the design in the x, g, and E directions. The dynamic stability and the possibility of galloping were also checked. Strong winds can occur several times a year, causing uncomfortable building mqtion. In order to avoid this problem, a damping systcm has been installed to reduce the acceleration in they direction. The building site is located in a very active seismic area. The largest eanhquakes in this zone to dare were of magnitude 8. A special seismic analysis was performed using the data of the three largest earthquakes that have originated in this area in order to model the earlhquake waves and the maximum possible accelerations for the ACT Towcr site. These 3 earthquake waves were 416 gallsec (550 mmlsec) (Ansei Tohka earthquake); 150 gallsec (320 mmlsec) (Nohbi earthquake): and 332 gallsec (850 mmlscc) (Tohnankai earthquake).

1

.

1

i

4 m (13 ft) office: 3.15 m (10 f t 4 in.) hotel 17.5 m (57 f t 5 in.) max. office: 10 m (33 ft 10 in.) hotel 850 mm (33.5 in.) office: 700 mm (27.5 in.) hotel 3.2. 6.4 m (10 f t 6 in.. ?I ft) office: 3.2, 4.27 m (10 h 6 in.. 14 ft) hotel 135- to 180-mm (5.25- to 7-in.) concrcte 750 by 600 mm (30 by 24 in.) 3.2 and 6.4 m (10 ft 6 in. and ?I ft) X- and K-braced framer

Braced frames were used lo increase the stiffness of the ACT Tower (Fig. 4.13) and to achieve an optimum structural system (Figs. 4.14 to 4.16). Three u.ind-tunnel tesls were performed:

I. A wind pressure test to evaluate facade pressures 2. A wind force test to measure the horizontal force, overturning moment, and tor. sional moment

I

Fig. 4.13

ACT Towcr. Humnmolsu City, Jnpnn.

70

Lateral Load Resisting Systems

M i c a 1 Structural Plan (Hotel)

>pica1 Structuroi Plnn (OCrice) Fig. 4.14 'Typical slruelurul plunr; A C T Toner.

[Chap. 4

72

Lateral Load Resisting Systems

Sect. 4.11

[Chap. 4

Braced Frame and Moment Resisting Frame Systems

73

Ti%-

I!

Year of completion Height from street to roof Number of stories Number of levels below ground F n m e material Typical floor live load Basic wind velocity Maximum lateral deflection Design fundamental period Design acceieration

Ii

Earthquake loading Type of structure Foundation conditions

.

Nikkeu Sekkei Ltd. with Portopia ~ o t ~ l Design O f i c e Nikken Sekkei Ltd. with Portopia Design Office 1981 112 m (367 ft) 31 2 Hotel Structural steel 1.8 kPa (36 psf) Not available 350 mm (13.75 in.) 3.5 sec transverse; 3.6 sec longitudinal 20 mg; 35 mg for seismic loading 2% C = 0.08 Moment frame and braced frame Fill over alluvial and diluvial strata Raft on prestressed concrete driven piles 3.02 m (9 ft l l in.) 7.5 and 6.75 m (24 ft 7 in. and 22 ft 2 in.) 800 m m (31.5 in.) 7.5 m (24 ft 7 in.) Steel, grade 400 and 490 MPn (58 and 70 ksi) 5th floor and above; concrete-encased steel below 5th floor 130-mm (5-in.) reinforced concrete

Columns Size at ground floor Spacing Material Core

I100 by 1100 mm (43 by 43 in.) 7.5 m (24 fi 7 in.) Steel encased in 24-MPa (3400-psi) concrete 600-mm (24-in.) concrete shear walls below 5th floor, smctural steel rigid frames 5th floor and above

Tllr typical floor pi2n of the Kobe Ponopix Holcl (Fig. 4.17) is .an oval, rncnsuring 7j.5 m (24.4 Ir) in the earl-weal dirccrion and 13.5 rn (4.4 fr) in the north-soutl~dirucrion IFlp.

Fig.1.16

Y5A frame elemlion; ACT Tower.

4.18). Above the fifrh floor of the high-rise p m . strength and ductility are provided hy

74

Lateral Load Resisting Systems

[Chap. 4

using a reinforced concrete rigid frame. The fifth and lower floors, which have a larger story height. have a composite structure of shear walls and rigid frames made of steel encased in reinforced concrete (Fig. 4.19). The site is part of about 500 ha (1200 acres) of artificially reclaimed ground. which has been filled over a oeriod of 10 years, starting in 1965. Before building construction commenced, the site Was preloaded. theoretically completing settlemen~ofthe former 12-m (40-it)-thick sea-bottom clay layer. Because the building weigh1 is about 100.000

Ik

Sect. 4.11

Braced Frame and Moment Resisting Frame Systems

tonnes (1 10.000 tons), a basement withgood foundation load balance was possible, with the weight of h e excavated soil being designed to exceed the weight of the building. Piles of about40-m (130-11) length were used. The building is supponed by using the diluvial layer as the bearing stratum. In pile design, pile groups were used wherever possible to cope with unmeasured ncgative friction. Structural safety was confirmed by performing a seismic response analysis of the building-pilc-bearing stratum composite form against horizontnl seismic loads. The floor plan has an unusual form, so various wind tunnel tests were performed to investigate such factors as the wind force coelficicnt. the wind pressure coefficient, nmbienl wind velocity, and the dynamic stability against wind. In everything from the structure itself to cladding matcrinls, external doors and windoms, and ground-lcvel wind velocity, wind tunnel test rcsulls were used to ensure adequate safety and serviceability.

Fig. 4.18 Typicul slructurul noor plnn; Kobe Purlopin Hotel

Fig. 4.17 Kobc Porlnpiu Holcl. Robe, Japan.

75

Lateral Load Resisting Systems

Braced Frame and Moment Resisting Frame Systems

8:;:

77

-?,..

.*+.

ah

Nankai South Tower Hotel Osaka, Japan

@

* ,. j..,,

18, &(

Architect

Swctural engineer 41 :Year of completion I $& Height from street to roof @ .,g~, Number of stories ~.~. *.~. :*.: Number of levels below ground , ,:

I,S

'A, : :I:

&~ .?,. 73,'

Building use Frame material

.:.

.,:

Typical floor live load Basic wind velocity Mnximum lateral deflection Design fundamental period Design acceleration .. .,.,,. ,:, . ..

Design damping Eanhquake loading Type of structure

Foundation conditions Footing type Typical floor Story height Beam span

... 2:.

/

\

I

9

VrnrnesorR; Kobe Portoplu Hofcl,

cuur1;lin \$:dl 133~11311) ur 1.)1311g. A iIrUClUr.lli51 ?Xpr~:isinnfur tile e \ l ~ ridr envelope msy hc lull? rc;~liz~.J b! hexil1,>r.~!-r31Jen~.str:,li~~~>. TI,< ~ L i l l d n !!L~i l l l i).st?rn 15 1hc.n infilled i,etre~.n the coi&~ and spandrel beams. with II resultino reduction i n claddine cost. An eariv * exampie o f such a iubuiar b u i l d i n in rcinforccd~oncreteis shown i n Fig. 4.91. The behavior ofrrarnrd tubes under Interel load is indicated in Fig. 4.92, which shows the distribution o f axial forces i n the exterior columns. The more the distribution is similar to that o f a fully rigid box cantilevered at the base, the more efficient the system will be. For the case o f a solid-\$,all tube. [he distribution of axial forces would be expected to bc uniform over the windn.nrd and Iccivard \tSsllsand linear over the sidcrvnlls. As the tubular walls are punched, creating the beam-column frame, shear frame deformations

Fig. 4.91

Brunrwiek Building, Cl~icugo.lllinoir.

193

~ d ~ r ~r o a a~ o n e s ~ s r ~ nhysrems g

[Chap. 4

Sect 4.41

Tubular Systems

ore introduced duc lo sltear;lnd flcxurc i n the tubular mumbcrs as u u l l as routtons 01thc ntcmber loin&. This rcdtlccs the eilecti\e stlffnrss Of lbe systeln as a cantilever. The extent to which h e actual axial load distribution i n the tube columns dcoartr;- from the ~. idesl is rcnndd the ",hear lag effect." I n behavioral terms. the forces i n the colurnns toaard lltu lniddls u i t h e flange frnmus lq behind those nearer the conter and are tltua less than fully ulllized. Limiting the shear lag ellect is essential fnr oplimal de\.elopmen~o f the :ubulnr system. A rc3son;1blr. objcctit,e is l o strivc toward a1 least 7% effiricncy sucll [hat the cantilever component in llte oterall rystcln deflection ondsr u i n d load dnminatus. Thc 1r;tmed tubu i n structural slsel rsquirus wcldinp oftlte heam-column join1 tu du!clop rigidity and continuily. Tllc ~ o n n 3 t i o n ofahric~tcd f 1rr.u elemenlr, rrltcre all welding is p:rformcd i n llte shop i n a horizonwl position, has made the alrsl-frame tuhe s ~ $ . tem more practical and efficienl, as shown i n Fie. 4.93. The trees are then erected-bv ~, bolting the ipandrcl bcotn* togelher ak Inidspan near thc pnint o f innrxion. The column spacing i n steel-fmntrd tubular buildings lnust be ~.ralualcdto b~l;tnce llte nerds for higher cantilever dfiicicauy throuph clorcr anactnkr rvitll increased F ~ h r i cation costs. The use ordeeper, built-up sectioni versus roiled G m b c r s is also a matter o f cost-effectiveness. A survey o f steel quantities for completed tubular buildings is s l ~ o w nin Fig. 4.94. The buildings range from 40 to 110 stories. and column spacings generally range from 3 to 4.5 m (10 to 15 ft) on center, with spacings as close as I m (3.28 ft) i n the case of the 110-slory World Tradc Center twin towers. New York (fig. 4.95). These towers are examples whereby the structuralist notion o f a punched wall tube with extremely close exterior columns is architeclurally exploited to express visually the inherent venicality o f the high-rise building.

~.

~

Fig. 4.93

Typical tree crcction uniL

Cantilever componenl Shear frame component

I

I

Elevation

Sway

Dlslribullon w l h w shear lag Actual axial stress

shear lag Wind lorce

Fg.4.92

t

Frulncd tulle i~clv~rior.

HEIGHT (in) Vlg. 4.94

Conlilcv~rsystems, stccl qunntity versus hciglxt

195

Lateral Load Resisting Systems

196 3

The Trussed Tube

,\, ihc tubular concept; were being dcreloprd in ihr 19605, il became Jppdrent that

thcrr was a cenain building height n n g e for which the framed tube could be elficlenll) adaoled. For rrry 1311 buildings. lhe dense grid of beam and column members has a d t =id;d impact onihe facade aGhitecture. The need lo control shear lag and improve the

I

9

\Ysrld Trndc Center, New Y n k .

Tubular Systems

[Chap. 4

lCo,mrry rfLrrlii. Robcrrrnr, n ~ i ~ l . i r m r 1

systemefficiency can only be realized by relatively small perforations in the tubular walls. The problem becomes particularly acute at the base of the building, where archi1 @$ teclural plannine lypically. demands open access to the bulldine interio; from ihe surrounding infrastruaurd will1 as lilrlc encumhr;mre 2s possible {om the sxlerior fr;~mek.; n,orI;. A number ofulcgant solutians inrolving Ole transfer and rcmovnl oftlle e~turi,,r columns at the base of the building have been iomulated (Figs. 4.91.4.95, and 4.96). '".~~t~pcharnc~eristically include an associated material premium. The trussed tube system represents a classic solution for a tube uniquely suited to thc qualities and c h m c l e r of structural steel. The ideal tubularsyslem is one which intercon-

I.,

~. Lateral Load Resisting Systems

,

.

Sect. 4.41

[Chap. 4

Tubular Systems

The bundled tubc concept allows for wider column spacings in the lubulu walls lhan w o ~ ~ ibr d oossible with unlv lhc eatrrior framed lube form. 11 is his sp3cine uhicll rnnkes it possible to place inierior frame lines withoul setiousiy c ~ m ~ r o ~ i s i n g ~ i n l e r i o r space planning. In principle, any closed-form shapemay be used to create the bundled form (see Fig. 4.102). The ability to modulate the cells vertically can create a powerful vocabulary for a variety of dynnmic shapes. The bundled lube principle therefore offers great latitude in the architecturnl plnnning of a very la11 building.

*.?;s.::!:s .,2

,

ENDCHANNEL TRUSSEDTUQE

MOMENT RESISTING FRAME OR

FRAMED TUBE

Fig. 4.99 Pnrtiul Lubulnr ryslcrn.

-COLUMN

AXIAL LOADS DUE TO WIND CASE (A1

::: s.. 0

0

114 PLANS

ttttttt Fig. 4.98 Trurrcd tubc, grurity loud rrdlrlribstion.

TUBE

TYPE

EXT. TUBE

EXT.

SIZE

69m x 69m

46m r 4 8 m

HIW

6.65

9.60

0c0101

0.61

0.75

EXT. TUBE

BUNOLEO TUBE

23m x 23m 19.00 0.66

6.65 0.78

Fig. 4.100 Sludy of tul~ulorcllicicnry.

69m x 6 9 m

Lateral Load Resisting Systems

202

Sect. 4.41

[Chap. 4

Tubular Systems ,03

PROJECT DESCR~PT~ONS,FRAMED TUBES

r

COMPRESSIVE STRESS

Amoco Building Chicago, Nlinois, USA Architect

STRESS

(a1

FRAIAING PLAN

1:ig. 4.101

Ibl

Uundlrd

SHEAR LAG BEHAVIOR

tube bchuriur: Sears Tower, Clnicugn, lilineir.

Footing type

Typical floor Story height Truss span Truss depth Truss spacing Material Slab

Columns Spacing Material Core

i

I

3.86 m (12 ft 8 in.) 13.7 m (45 fr) 965 mm (38 in.) 3.05 m (10 ft) Swctural steel 140-mm (5.5-in.) lightweight concrete slab; 35 MPa (5000 psi) on 38-mm (1.5in.) steel deck Folded plate, size not available 3.05 m (10 ft) center lo center Stcel, grade 250 MPa (36 ksi) Structural steel frames carrying gravity loads only

Fig. 4.102 hlndular tuher.

/, ,!j

l

Edward Durrell Stone with The Perkins and Will Partnership The Perkins and Will Partnership 1973 342 m (1123 A) 82. 5 Office Structural steel 4 Wa (80 psO 1.4 X Chicago code HI400 Not applicable Perimeter fnmcd tube Silty clay, sand, and gravel over massive dolomitic limestone Concrete caissons. 1.5 to 3.8 m (5 fl to 10 ft 3 in.) in diameter. approximarely 24 m (79 ft) long

Swctural engineer Yenr of completion Height from street to roof Number of stories Number of levels below ground Building use Frnme material Typical floor live load Basic wind velocity Design wind load deflection Earthquake loading Type of svucture Foundation conditions

MASTER GRID OF COLUMNS AT BASE

1

The innovative structural concept applied to this 342-m (1 123-ft)-high building resulted from the desire to achieve an efficient, simple to erect structure utilizing a perimeter tube whose behavior would closelv anoroximate that o i a oure cantilever (Fie. 4.103). . The lubc compriaca uolulnns uf V-rhaped kcel plaw 3nd du:p ubxnnul.shapud bcnlplat: spandrel bcams shop-fabncalcd Inlo 3-stor) Irccs. Tb:r< arc 64 sucll columns ;,t 3-

.

..

-

I

I

f&'

Lateral Load Resisting Systems

204

Sect. 4.41

[Chap. 4

Tubular Systems

205

i: : i.

m (10-11) centers around the perimeter, plus solid steel plate walls to the reentrant corners. The free inner edges of the columns are stiffened by heavy angle sections. Connections between spandrel beams comprise simple high-strength bolted joinL5, whereas column splices are welded at lower stories and bolted or welded at upper stories. The floors are generally supported by 13.7-111 (45-11)-span trusses at 3-m ( 10-ft) centers. Trusses at successive floors attach to alternate sides of a column to effectively cre-

Fig. 4.103

Amoco Uutldtng, Chtcugo, lllinuis. (Pl>ninh? Jrrr BairB.)

::

ate a concentric load in the vlane of the wall. At the buildine corners the shorter-soan diagonal girder and attached'beams are wide-flange sections. ?he 4000 essentially identical lrusses and the comer beams were mass-produced in an assembly line. r irom thin steel olate .;oread Economv was achieved bv creatine a ~ e r i m e l c frame !,.,.i,over as much of the facade as was architecturally acceptable and by maximizing the ;?:?'number of geometrically identical elements. The arraneement also negated the need for sublramine - for the exterior curtain wall. The space within the V-shaped columns was used Tor air s h a h and hot and chilled water pipes for the perimeter zone. The interior zones were s u e ~ l i e dfrom vertical shafts in the bore The building contains45.900 lonnes (50.506 tons) ofsteel,ofwhich 37% is in beams and trusses and 63% in columns and reentrant corner wnlls.The r\reieht ofsteel amounts

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.

. -.

Sect. 4 41 181 West Madison Street Chicago, Illinois, USA

Archilcct Structural engineer Year of completion Height from streel to roof Number of stories Number of levels below ground Building use Frame malcrial Typical floor live load Bnsic wind selocily Maximum lateral deflection Design fundemenla1 pcriod Design acceleration Design damping Earthquake loading Type of slructure Foundation condiiions Footing type

Typical floor Story height Benm span Benm spacing Benm depth Slab Columns Spacing blalcrial Core Thickness a1 ground floor

Cesar Pelli and Associates with Shaw and Associates Cohen-Barreto-Mareherlas Inc. 1990 207 m (680 ft) 50 1 omce Concrete corc, steel perimeter frame 2.5 kPa (50 psf) -13 mlsec (97 mph). IOO-yr rclum period 400 mm (16 in.). IOO-yr return period 8.3. 6.7 see horizontal: 6.3 sec lorsion 18.4 mg peak I .5% senaiceability Not applicable Concrete core lube with stccl perimeter tuhc Hardpan. 1.7-MPa ( 2 0 . ~ ~capacity 0 Caissons. 24 m (80 ft) long. 1370 mm (4 fl 6 in.) in diameter, belled to 3-m (IO-ft) diameter 3.96 m (13 ft) 10.36 m (34 ft) 3.05 m (10 fr) 530 mm (21 in.) 140-mm (5.5-in.) composite metal deck W350 by 745 kglm (14 in. by 500 Iblft) 6.1 m (20 ft) Steel, grade A572. 350 MPa (50 ksi) Central concrete corc. 62 lo 28 MPa (9000 to 4000 psi) 400. 500, 660 mm (16, 20.26 in.)

The I 81 West Madison Sbcet lowe r is a 50-story office building located at Madison and Wells Streets in [he Chicago Loog1 (Fig. 4.104). It is a point lower, with multiple setbacks and a distinctive cro\r8nthat recalls the sculpturally expressive skyscrapers of the 1920s. This is also n tower for the 1990s. It is clearly organized as a square floor plen with n center square concrelc core and column-free office space (Fig. 4.105).

Fig. 4.104

181 \Veal hlidiron Slrccl, Chicngn, illlnoi~

Lateral Load Resisting Systems

208

[Chap. 4

181 West Madison is the tallest combination core building in Chicago. The central concrete core is surrounded bv a sWctuml steel frame and a com~ositefloor svstem. The squa~ccore is 50 stories tA11. for a totnl height of 207 m (680 fi). rile core and columns a the base of ihc building are rupponed by cnissons and gradc heams. Of the cnissons in the uroiecC 25% existed. Transfer-crade beams between new and existing cnissons were uskd io take the tower's wind an; gravity loads. The foundation wall on the east side of 181 West Madison required underpinning as it is a common wall with its neighbor, 10 South LaSalle StreeL Interior spans of 13.1 m (13 ft) ailowa column-free interior space for maximum user flexibility. The many setbacks at the top of the building require all the perimeter columns to be fransferred several times. In addition, the columns on either side of the

I

I

I

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I

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sect. 4.41

Tubular Systems

loading dock at ground level are also transferred to increase clearance for trucks. E stcel is less than 59 kg/m2 (12 psO. lobby. Clad in warm white, grey, and green marble, the lobby's

;.?&$

I

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I -+ I I I I I I I Fig. 4.105 8th to 14118 noor rramine pian;

181 \Vest hlndirun S t r c c ~

210

Lateral Load Resisting Systems

[Chap. 4

Sect. 4.41

Tubular Systems

AT&T Corporate Center Chicago, Illinois, USA Architect

Skidmore Owings and Mcrrill

Structural engineer

Skidmore Owings and Merrill 1989

Year of completion Height from street to roof

270 m (886 R)

Number o f stories

61

Number o f levels belo\%,ground

2

Building use

Oflicc

Frame material

Conlpositr slccl-concrete perimeter liarlie. steel interior columns. stccl floor beams

Typical floor live load

4 kPa (80 psr) lct,cls 3 to 30: 2.5 kPa (.iO psi) Ic\,c~s 31 to 59

Basic wind \,elocity Maximunt lateral deflection

35 mlsec (78 rnplt). IOU-yr return HI700

Design fundantcntal period

6.5 sec

Design acceleration

20 rng. IO-yr return

Dcsign damping

I to l.5 aurrice;lhility Not applicable

Earthquake looding Type o f structure

Exterior concrcte-fromcd tubc with iliterior frfieity-luad culunins. t m r r s . :lnd bei~o~s

Foundation conditions

18 m (60 i t ) o f clay over liardpan

Footing type

Belled caissons on 1iardp;ln

Typical floor Story lheigltt

4.0111 (13 ft 2 in.)

Truss span

14.6 m (48 i t )

Truss depth

914 rnm (36 in.) 4 . 6 m ( l 5 It)

Truss spacing Illaterial

Steel. grade 230 and 350 h,IP;1(36 and 50 ksi)

Slah

63-nun (1.5-in.) light\\,cight cuncrctc on 76-mm (3-in.) o~etaldeck

Columns Size at ground lloor

I422 by 813 oim (56 by 32 in.)

Spacing

4.6 ~n( 1 I 5 111

ivlnterial

Nornt;il-\\,cigltt concrstc, 56 tu 35 MP;t (5000 to SUOU psi)

Cure

Steel he;~msand columns for gravity load only

Tlte ATSlT Cnrporatc Center (Fig. 4.106) consists o f a 61-story uflicu to\i,cr \\,it11 rentable areas o f fluor plates ranging front 3250 m2 (35.000 1'1') on the lowest floors to

. .

Fig. 4.1116

ATST Corpunltc Ccntcr, C ~ I E I ~Illtnots. ~ C ~ . (PimrA. - , ,., . .. .

.,i?.. .,.

227

Fig.4.116 Framing plan for noors 14 l o 23; hlcilon Dank.

Tubular Systems

Sect. 4.41

- ..

229

Comolicatine the nroiect was that none of the 52 columns in the tower continued directly to the ground. Instead, all of the perimeter columns are either sloped o r picked up bv msses. The sloped column system enabled the transfer of columns into new positions, allowing for the enlargement of the lower floor plates while still maintaining col,:.u.mn-free 2. . lease space. .*.. - I , Depending on the architectural constraints, groups of columns slope at different floors. The sloped columns always form a symmevical system, whereby sloped columns on opposite sides of the floor balance out the overturning forces resulting from the slope. In numerous cases, columns are terminated upon pick-up tmsses, which are also sloped to link up with their repositioned supporting columns. A unique sloped column system occurs between the tenth and thirteenth floors, where the four inside comer columns are supported by an A-frame. Each A-frame generates significant lateral forces, which are all balanced out by again balancing one corner against the opposite corner. The floor diaphragm, being the link between all columns, plays a kcy role in transferring these balancing forces across the floor. The mosi critical diaphragms arc the fifth- and sixth-floor diaphragms where, in addition to supporting most of the sloped columns, the lateral wind forces are transferred from the nerimctcr to the core vertical w s s . r With some slopcd columns generating 7000 liN (450.000 lb) in lateral force, the designer chosc lo place a 13.4-111 (a-ft)-deep steel horizontal truss within the floor dian-hraam. ~hese'trusses helo transfer the bind forces to the core while passing the ~~r~~~~ sloped column forccs around the core to the opposite sloped column. At the core a vertical supertruss extends from the foundation up to the sixth floor. The supertruss is constructch of steel wide-flange shapes, with the four comer columns encased in 3000- by 3000- by 600-mm (10- by IO- by 7-ft)-thick L-shaped concrete shear walls, thereby forming a composite steel nnd concrete supenruss. The supenruss is divided into two parts, a large 13.7-111 (45-ft)-high truss between.levcls 6 and 3, and a single X truss on each face of the core, extending from the third level down to the foundation. The transfer of latcral loads out of the oerimeter and into the core at the sixth floor forntr an optimum conibin3tinn 01 the core and perimdtcr 1stur:il system,. Triinjfcmng the wind lateral force\ to the core ;it ilie r i ~ i hflour results in zero uplilt forccs upon the foundations.

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I-+&&+.. Fig. 4.117

Eurl and

west lncrr of pcrirnelcr tui,c: i\lcllnn Dunk.

! 230

Lateral Load Resisting Systems

{Chap. 4

Tubular Systems

. S a d . 4.41

Sumitorno Life Insurance Building Okayama. Japan

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

Typical floor live load Maximum lateral dcnection Design fundamental period Design acceleration Design damping Earthquake loading Type of structure

Foundation conditions Footing type Typical floor Story height Beam span Beam depth Beam spacing Material Slab Columns Size at 2d floor Spacing Moterial Core

Nikken Sekkei Ltd. Nikken Sekkci Ltd. 1977 75.3 m (247 ft) 21 2 Office Structural steel from 4th noor up: concrete-encased structural steel and shear walls below i t h noor 3 kPa (60 psO Not available 2.08 sec transverse: 2.01 sec longitudinal Level 1 EQ, 20 mg; level 2 EQ, 25 mg 2% C = 0.14 Structural steel perimeter tube from 4th floor up: arched conciete-enca5ed steel fnrncs and shear u-alls from ground to first noor Gravel Raft

3.5 m (1 I ft 6 in.) 9.9 m (32 ft 6 in.) 700 mm (27.5 in.) 2.5 m (8 f t 2 in.) Steel, grade 400 MPa (58 ksi) 150-mm (6-in.) concrete on metal deck 400 by 300 mm (16 by 12 in.) 2.5 m (8 ft 2 in.) Steel, grade 190 MPa (70 ksi) Steel frame

The main structural system of this building is a nearly square tube structure, which employs a peripheral frame in an integrated fashion (Fig. 4.1 IS). In appearance, tile tube structure has no directionality. The peripheral hearing walls of the l'irst and second floors support the upper structure a ~ i dhave a large arcli-shaped opening. The axial forces of the external columns of the upper tube structure are transferred by the nrcli-

Fig. 4.118

Sumito~noLife Imurnncr Building, Okoynmo, Japan,

232

Lateral Load Resisting Systems

Tubular Systems

[Chap. 4

shaped bearing walls of the first and second floors to the L-shaped wall columns at the four comers and thence to the foundations via bearing walls below grade. The arch-shaped bearing walls of the first and second floors are of reinforced concrete construction with internal steel msses (Fig. 4.119). The embedded steel structure is designed to remain elastic for long-term vertical loads and for short-term horizontal loads. The bearing walls were modeled as flat plates and analyzed by finite-element analysis. (The steel msses were taken into consideration.) Analysis of the earthquake response was performed using a rnultimass model, which combined the upper tube struchlre with the arch-shaped bearing walls of the fust and second floors. For accelerations of 3500 mmlsec2 (1 1.5 ftlsec2) during a large ennhquake. the arch-shaped bearing walls remain within the allowable elastic stress range. The primary natural period in the vertical direction (considering vertical rigidity of the arch-shaped bearing walls) is 0.179 sec, so there was almost no response from the arch-shaped bearing walls due to venical earthquake motions. The typical floors (Fig. 4.120) are supported by 700-mm (27.5-in.)-deep trusses at 2.5-m (8-ft 2-in.) centers spanning 9.9 m (32 R 6 in.). The spnces between the truss web members allow for the passage of ducts and pipes. The truss top chord is connected via stud shear connectors to the concrete slab. The increase in stiffness results in a frequency of vibration of h e floor in excess of 9 Hz.

Fig. 4.119

Fmmcnork; Sumitomo Life Inruruncc Building.

Lateral Load Resisting Systems

Sect. 4.41

Tubular Systems

Dewey Square Tower Boston, Massachusetts, USA

Architect Structural engineer Year of completion Height from street to roof Number of stories Number of levels below ground Building use Frame material Typical noor live load Basic wind velocity Maximum lateral deflection Design fundamental period Design acceleration Design damping Earthquake loading Type of structure Foundation conditions Footing type Typicnl floor Story height Beam span Beam depth Beam spacing Material Slab Columns Size at ground floor Spacing Material Core . .. ......

Fig. 4.1ZU Txpicul structurui flour pins; Sunnitunls Lilc lniurdnru Uuilding.

Pietro Belluschi Inc. and lung Branncn Associates Inc. Weidlinger Associates 1983 182 m (597 ft) 46 2 Office Steel 2.5 Wn (50 psf) 42 mlsec (95 mph) 450 mm (I8 in.). 100-yr return 5.5.4.3 sec 23 mg peak. 10-yr return I % serviceability: 2% ultimate Not applicable Perimeter tube Stiff silty clay over compact glacial till Mat. 1800 lo 2600 mm (6 to 8 ft 6 in.) thick 3.81 m (12 ft 6 in.) 9.1 m (30 ft) 400 mm (16 in.) 2.3 m (7 ft 6 in.) Steel 133-mm (5.25-in.) lightweight concrete an metal deck W350 by 1088 kglm (W14 by 730 Iblft) 4.57 rn (15 ft) Steel, grade 350 MPa (50 ksi) Braced steel frame, grade 350 MPa (50 ksi)

After having examined many alternative systems, project designers at Weidlinger Associates concluded that a steel structure with a rigid frame around the perimeter was most economical for this 46-story building and would resolve the requirements for integrating the structure with the curtain wall (Fig. 4.121). Ressstance to wind and seismic forces is provided by the framed tubc forming the tower's penmeter. To economize

Lateral Load Resisting Systems

Tubular Systsms

[Chap. 4

on field work, particularly field welding, spandrel units consist of trees with columns and welded eirder stubs. Field connections of the girders at the centerlinc between cnlumnr are golted shear connections. Spandrel girders on lyptcal floors arc gcncrally 1143 mm (-15 in.) deep. \.:lr).ing irom a minimum or900 mm (39 in.) at the lop oiihe building lo 1245 mnl (49 in.) a! lllc boltom. Columns are built-up members 760 mm (30 in.) deep along the building face. except where rollcd sections are used above the thirty-third floor. Perimeter columns arc ~

arranged to provide open comers, that is, the ladder section always ends with a beam stub at the comer. This scheme avoided the complication of three-dimensional corner columns with welded stubs eoina in two directions as well as the hiaxial bending problem of a comer column. since ail of the structure's lateral stiifness is proridednr~ound the penmcter. nil interior bean-lo-beam connccliuns arc o i l h e simple sllcar type. A varietv of steels is used throuehout - the struclure. Exterior columns and inlerior ~:&floor framing are of A-36 steel, girders and interior columns are A-572 grade 50, and built-up interior columns are g n d e 42. High-strength steels were chosen where the desien w& eovemed bv streneth considerations. Where the desien aovemcd - is .primarily. . b) dcfor~nalioncriteria. as for drturiur columns, lower-strength l e e i s ware oscd. The lower has o slructural dcpth u i 36.57 m (120 it) ulth a height-lo-depth ratio of almost5:I. This.. couoled with its unusual shaoe.. sueeested the useof a windtunnel test !o verify both the magnitude and the local variations of wind forces. The wind tunnel test results very closely matched the overall forces required under the Massachusetts code. Local hoi soots here found to exist oarticularlv a t the intersection between the tower and the atrium. The analysis of the suucture for lateral forces yielded information useful for future oroiects. It is well known that the effect oishear deformation becomes mnenified with an a increase in the depth-to-span ratio of the beam. Since in a frame such as this, the depthto-span ratio is on the order of 15. shear delormations contribute a large part of the total lateral deformation of the swcture. Soecificallv. in this case it was found that the lateral deflection due to drift of the buildingLan be aGibuted in roughly equal parts to:

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-

Overall deformations of the frame (shear deflections) Column shortening (bending defleclion) Shear deformation of beams and columns Since the girder webs are relatively thin compared to the column webs, the major portion of the shear deformation is attributable to the beam web. Wherever possible in the eslablishcd program, the steel fabricator elected to substitute fillct weldine- for this connection between the spandrel -eirder flanees and the penmuter columns. This was cltoscn w c r the specified full-pcnclmlion weld. \VBcnevcr the ercction equipment uouid nllo!, the iabricnlor uscd 1-0-stor). tiers for !hi. e~teriorcolumns. There cunsisted of the lull 7.62-m (25.11) columo. ~ i l htuo sp;indrel girder stubs oo each side. The spandrel girders were then bolted togcthcr nl mldsp~n This method kept field \$,elding to 2 m~nimumas well ns expediting the erc:tlon In erectine- the steel tower, three self-climbine - tower cranes were used in lieu O F the more conventional two. This ensured maximum erection speed and facilitated the ercction of the precnst concrete panels, also p a n of the steel contractor's work. Dewey Square Tower is granite-clad on the lower two floors, with precast rain-screen panels reachine from the third floor to the s l o ~ e d-class crown of the fanv-sixth starv. Continuous bands of tinted reflective glass alternate with bands of exposed granite aggregate l for the panels were dcvclopcd wilh input set in white cement. S l ~ c t u r a connections from both the panel fabricator and the steel contractor. The typical panel is attached by two load-bearkg connections and two lateral connections shop-welded to the perimeter columns. Floor construction consists of a 50-mm (2-in.) composite deck with an 83-mm (3.25-in.) lightweight concrete topping. erade and rises 180 m (590 it). The torvcr starts on a concrete mat two stories below . f l ~ sI t - ru 2-m (6- to 8-frl-(hickconcrete m:ti reris on hardpan, nhi:h protrdcr ; ~ neconnnli;;ii i b ~ n r l ~ t i uTilt n are;, uf lhr. building surro~ndingthc i.>\\cr 113s cnlumns rdsting on spread footings and incorporates an undcrdrain system below the subbasement slab.

.

-

Fig. 4.121 D e w y Squure Tower, Boston, hlnrsnchusctb. (Phoin lir S a w Rorrrirbn1.l

.

Lateral Load Resisting Systems

[Chap. 4

Morton International Chicago. Illinois, USA

Architect Structural engineer Year of completion Height from street to roof Number of stories Number of levels below ground Building use Frame material Typical floor live load Basic wind velocity Design wind load deflection Design fundamental period Design acccleration Design damping Eanhquake loading Type of structure Foundation conditions Footing type Typical floor Story height Beam span Beam depth Beam spacing Material Slab Columns Size at ground floor Spacing Material Core

Perkins and Will Perkins and Will 1990 170 m (560 ft) lo top of clocktower 36 plus clocktower 1 Office, parking, and retail S l ~ ~ t ~steel ral 2.5 W a (50 psfl 34 mlsec (75 mph) 330 mm (13 in.). 50-yr return 4 sec Estimated 15 mg peak, 10-yr return I lo serviceability Not applicable Perimeter framed tube with transfer truss at low level Stiff clay Belled caissons bearing on hardpan

Sect 4.41

Tubular Systems

239

The 36-story structure has typical floor spans of 12.6 m (41 ft 6 in.). but spans varying from 19.8 lo 21.3 m (65 to 70 it) were required to span the railroad tracks. This was achieved with n series of 6-story-deep Vierendeel frames consisting of two 3.05-m (10ft)-deep plate girders, one at level 2 and one at level 8, connected by fully welded vertical and horizontal members. For a building of this height, a braced core would have been the obvious means of resisting wind loads. However, in lhis case the railroad tracks

3.81 m (12 ft 6 in.) 12.6 m (41 f t 6 in.) 533 mm (21 in.) 3.05 m (10 ft) Steel, grade 350 MPa (50 ksi) 140-mm (5.5-in.) lightweight concrete on steel deck Built-up 1640 kglm (1100 Iblft) max 4.57 m (15 ft) exterior; 9.1 by 12.6 m (30 ft by 41 f t 6 in.) interior Steel, grade 350 MPa (50 ksi) Steel frames supporting gravity loads only

The Morton International building comprises a 13-story base containing commercial floors and parking for 450 cars, topped by a 23-story ofice tower (Fig. 4.122). The site fronts the Chicago River and contains existing railroad tracks, which had to remain fully operational during consmction. Almost a quarter of the site was unable to accommodate any footings and the remainder rcquircd large spans across the tmcks. Several interesting transfer systems were designed lo overcome the site restraints. Pig. 4.122 Morton lntcrnnlionol. Chicago, lliinoir. (Plzoro I,? Hrdrich-Blerring)

240

Lateral Load Resisting Systems

Tubular Systems

[Chap. 4

made this impossible and instead, a perimeter framed tube with columns at 4.57 m (15 ft) was adopted. The columns and spnndrel beams were shop-fabricated into 2-storyhigh "ladders" with site-bolted web plate connections at midspan of the beams. This design saved 1360 tonnes (1500 tons) of steel compared to an original design with perimeter columns at 9-m (30-fl) centen. The 13-storv structure presented major challenges, which were overcome by three separate transfer structures and unusual construction rrquirrmcnts. Street-level concrete transfer beams 2.3 m (7 ft 6 in.) deep nt 9-m (30-it) centers span the mcks lo allow a regular and efficient column setout above. T h e recond transfer svstem occurs above the roof to the southern end of the build~~~~~~-~ ing, where no footings were able to be provided in the tnck zone. Trusses with major members built uo from six 100- by 600-mm (4- by 24-in.) plates suspend one side of the

--..-...-.

n l e third transfer system occurs between levels 2 and 4 and serves to redirect two rows of upper columns into one row located to avoid the tracks. The entire vrnical structure above these transfer frames u a s erected to the roof lcvel, and the roof top trusses were erected cantilevering bcyond the floors belon. This section of thc bullding was erected 90 rnm (3.5 in.) out of plumb to dlow for the sway induced when the cantilewred section was erected and partially loaded. With the roof top trusscs erected, perimeter columns wrre suspended ham the free ends of the trusses.and the floors were erected in a conventional manner from the boltom up. To equalize dcfl:ctions and minimize difrcrentinl movement, a load-distributing longiludinal truss mas installed at level 8 between the suspcndcd columns.'lhis truss served 3 dual purpose in that it was also designed lo redistribute the column load to adjacrnt columns should aroof-top truss fail. The roof-top trusrrs were providcd u,ith sufficicnt capacity to allow them to cnrry t h ~ additional s load. This challeneine proicct - -. - received an nwnrd for Most Innovative Design of 1990 from the Structural Engineers Association of Illinois

.

'

Height from street 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 fundnmental period Design acceleration Design damping Eanhqualie loading Type of structure Foundation conditions Footing type

Typical floor Story height Beam span Beam depth Beam spacing Slab Columns Spacing Material

Cesnr Pelli Associates Walter P. Moore and Associates, Inc 1992 256 m (840 ft) 62 2 Oftice, corporate headquarters, retail Concrete 2.5 kPa (50 psf) 1.0-kPa (20-pst) partitions 35 mlsec (80 mph) at 10-m (3341) heighl HnOO, 50-yr wind 5.3 sec 12 mg peak, 10-yr wind 1.5% serviceability; 2.5% ultimate C = 0.53, Z = 0.15. Ru, = 7.0 intermediate moment resisling frame (IMRF) Perimeter tube Clay of variable thickness, 4.6 to 7.6 m (15 lo 25 it) over weathered bedrock 2.4-m (8-ft)-thick core mat on weathered rock: 9- to 30-m (30- to 100-it)-deep caissons (150 ksO. 1.5 to 1.8 m (5 to 6 it) in diameter

+

3.86 m (I2 ft 8 in.) 14.63 m (48 ft) 457 mm (18 in.) posttensioned 3.05 m ( I 0 it) 117-mm (4.625411.) lightweight concrete one-way. 35 MPa (5000 psi) 1370 mm (54 in.) in diameter 6.1 m (20 ft) 55 MPa (8000-psi) concrete

The Nations Bank Corporate Center is a 60-story. 256-m (840-fl) tall building in the central business district of Charlotte. North Carolina (Fig. 4.123). The building is the tallest in the southeastern United States and will dominate Charlotte's skyline into the 2151 century. From a heavy stone base, the building rises with curved sides and progressive setbacks culminating in a crown of silver rods symbolizing Charlotte's nickname, "The Queen City." The exterior surface materials arc rcddish and beige granite

242

Lateral Load Resisting Systems

[Chap. 4

and mirrored reflective glass; the granite piers narrowing at each setback. The building will serve as the corporate headquarters for Nations Bank. A number of different feasible structural schemes were analyzed before Nations Bank and the developer selected an economical concrete frame. A reinforced . together concrd~cframe U 3 S ssl~ctcdbec3use it met both thc intricate geumetric rcquiremsnt, 01 thr. arcl~~tucr ;~ndthe d-munds of the detcloper for economy Sh3llow posttensioricd concrete floors were used to span the 14.6-m (48-ft) lease depths and to achieve the desired 3.9-m (12.5-ft) floor-lo-floor heights.

Sect. 4.41

Tubular Systems

243

The smctural system selection followed an intensive four-phase scheme development process. This process has been used successfully in swctural system selection for many other high-rise projects. The purpose of the structural scheme selection process is not only limited to finding the most economical structural system. but to finding the system that best resoonds to the overall buildine eoals. Nonswctural oorameters such as impact on lc~sing,column sizes and locations, shcar wall drop-offs, construction duration, floor-to-floor heights, fire nling and intcgrntion wilh mechanical systems arc also considered. The entire-team oaiicio&d in theselection orocess Thr. srleclcd all.concrcte scheme consists of a reit~forcudconcrele perimclrr lube struculre witl~calum~is spaced on6.1 rn (20 ft)centers.Thc perimeter lrwnr utilizes normal weleht concrele with slrenclhs rancinc from 41.300 lo 55,000 Wa (6000 lo 8000 psi). ~h;external tube was selected because it was the most efficient late& load resisting system. The tube also proved to be an economical method of dealing with the many setbacks and column transfers imposed by the building architecture. The floor system consists of a 117-mm 14.5-in.)-thicklichtweieht concrete slab soannine to 457-mm (18in.)-deep post-lension;d beams. The pasttenzoned beams are spaced 3 m (10 ft) =enters and span as much as 14.6 m (48 it). The 14.6-111 span provides column-free lease soacc from the core to lheperimeter.The shallow structural devth allowed the low floorto-floor height resulting in additional savings in skin cost. ~ i ~ h t w e i gfloor h t concrete was selected to minimize the building weight and to achieve Charlotte's unusual reouirements for 3-hr fire separation. A normal weirht - concrete slab would have needed lo be I50 mm (6 in.) tltick in order lo proiidc tlie Err. separation, substantially incrcasing not only the b~ildlngwcighl but also ths floor-lo-floor hcight. All lateral loads are resisted hv the external frame. The floor framinn- and core columns 3re sized for gravity loads. Lateral load niumcnls imposed by compatibility uf deformation uilh the cxtcrior frame were found lo bc ~nsignificanl.The corc columns were shaped to be wall-like Column sires ranecd from 0.6 by 5.5 m (2 by 18 it) at the lower le&l to 600 by 900 mm (24 R by 35 in.i at the top of the building;~hewalllike colunm shapes integrated very well with the building core. u

-

on

Fig. 4.123 Nutions Bunk Corporule Ccntcr, Ci~orlstle.North Cilrollnu.

Lateral Load Resisting Systems

[Chap. 4

Sect. 4.41

Bank One Center Dallas, Texas, USA

Architect Stmctural engineer Year of completion Height from skeet to roof Number of stories Number of levels below ground Building use Frame material Typical noor live load Basic wind velocity Maximum lateral deflection Design fundamental period Design damping Eanhquake loading Type of structure Foundation conditions

.'

John Burgee Architects with Philip Johnson The DatumIMoore Pafinership 1987 240 m (787 ft) 60 4 Office, parking Concrete-composite perimeter frame, steel core 2.5 kPa (50 psO + 1.0-kPa (20-psO pnrtitions 31 mlsec (70 mph) at 10-m (33-11) height Hl500, second order. 50-yr wind 6.8, 6.5. 3.5 sec 2.0% serviceability; 1.5% ultimate None Perimeter tube 6.1-m (20-ft) shnie and weathered limcstone over unweathered limestone

Tubular Systems

The engineering for the 148,000 m' (1.6 million ft') project is as complex as the architecture. Extensive value engineering studies were done during design development to analyze six floor framing systems and four wind framing systems. Design information for each was provided to the general conuactor, who in turn smdied scheduling and prices. All four wind schemes were variations of the perimeter tube. For the early compar:alive design studies, Dallas building code wind forces were used. The selected scheme

Footing type design allowable Typical noor Story height Beam span Beam depth Beam spacing Material

Columns Spocing Material

3.84 m (12 ft 7 in.) 14.69 m (48 R 2 in.) 457-mm (18-in.) 2.74 m (9 ft) Steel. A572 grade 50.50-mm (?-in.) composite metal deck + 89-mm (3.5-in.) 1i:httveight concrete 610-mm (2-it)-square 100-mm (4-in.). thick box column 7.6 m I25 ft) Steel. A572 grade 50

Bank Onc Ccnlcr is a postmodern to!\'er compictc rvith a monumental arched entry and curved roo[ line (Fig. 4.12-1). The 60-story oflice tower also Ins an atrium banking hail in its 6-story podium, semicircular arched roofs at the t\\,ent)'-sixth floor and quartercircle i,aulted skylights at the fiftieth, where the shope changes from rectangular to cruciform. On top is a cross vaulted arch clad in copper and pmnite.

1 :!.

Fig.J.124

Dunk Onc Ccnlcr, Dallus, Tcsar

246

Lateral Load Resisting Systems

[Chap. 4

has punched concrete walls at the building corners with infills of composite columns and steel spandrels; floors have a composite steel heam framing system. The building's nrchitecture requires a number of geometric changes as the stmctural frame rises above the below-grade levels. The cruciform shape above level 50 created two major structural problems. First, the perimeter tube had to be broken, leaving only two-dimensional rigid frames on each building facade. To control frame distortions under wind loading, two-story X-braced frames were added in the core. This required strenathened diaphragm . - floors to allow the transfer of wind shear forces from the irames to the pcrimetsr lube system btlou. Second, comer columns at the rccnuant corncrs of the cruciform hod lo be transferred lo provide culumn-free lease space bclow Icvel 50. Story-deep Vicrendccl trusses spanning 13.7 m (45 it) move these gravity column loads 10tltc perinieter wind frame and to the cure. Because of the relationship bet!\e:n corc and perimeter columns. lhr trusses ltad lo be supponed nt the corc by twoslury Vicrcndecl lrusscs spanning 8.5 m (28 it) to the building corc columns.

Sect. 4.41

Tubular Systems

Central Plaza Hong Kong

Architect Smctural engineer Year of completion Height from sweet to8 roof Number of stories Number of levels below ground Building use Frame material Typical floor live load Basic wind velocity Maximum lateral deflection Design acceleration Earthquake loading Type of structure Foundation conditions

Footing type Typical floor Story height Benm span Beam depth Slab Columns Size at ground floor Spacing Material Core Material

Nu Chun Man and Associales Ove Amp and Partners 1992 314 m (1030 ft) 78 3 Oifice Reinforced concrete 3 P a (63 psfJ 64 mlsec (144 mph). 50-yr rcturn, 3-sec gust 400 mm (15.8 in.), 50-yr return period wind Less than 10 mg. 10-yr rcturn period (typhoon wind) Not applicable Perimeter tube and corc Fill over clay over granite bedrock; granite bedrock. 25 to 40 m (80 to 130 it) below ground Machine- and hand-dug caissons to rock 3.6 m (11.8 ft) 12 m (39 ft) 700-mm (27.5-in.) reinforced concrete 1 6 a m (6.3-in.) reinforced concrete 2-m (6.5-A) diameter 8.6 m (28 ft) Concrete, cube strength 60 Nlmm' (8500 P") Shear walls 1.3 m (4 f t 3 in.) thick at base Concrete, cube strength 60 to 40 Nlmm' (8500 to 5800 psi)

When completed in 1992, Central Plaza was the tallest reinforced concrete building in the \vorld (Fig. 4.125). The site is typical of a recently reclaimed area with sound bedrock lying between 25 and 40 m (80 and 130 ft) below ground level. This is overlain by decomposed rock and marine deposits, with the lop 10 to 15 m (33 to 1 9 ft) being of fill material. A permitted bearing pressure of 5.0 MPa (56 ton/ft2) is allowed on sound rock. The maximum water table rises to about 2 m (6.5 fl) below ground level.

248

Lateral Load Resisting Systems

[Chap. 4

Tubular Systems

Sect. 4.41

Wind loading is the major design criterion in Hong Kong, which is situated in an -& fluenccd by typhoons. TheHong Kong code of practice for wind effects is bared on amend:, hourly wind speed nf 44.3 d s e c (99 mph). 3-sec gusls of 70.5 m/Sec (158 mph), and give$r, ,. rise to a l a t e d design pressure of 4.1 kPa (82 psO at 200 m (656 h),above pound level. 11 was clear from the outset that a multilevel basement of mnxlmum noor area be required. The design of a diaphragm wall. extending around the whole slte perimeter, i:fmrrer~s.~.roc)

273

Fig. 4.138 Typicul l r n m i n ~pin": 780 Third Arcnur.

Lateral Load Resisting Systems

274

[Chap. 4

were not exceeded. The cladding design requirements were, however, upgraded on the basis of the wind tunnel test results. The projected 10-yew return maximum acccleralions of 12 mg registered well within the occepled industry limits for office structurcs. Results from B e analyses performed for 780 Third Avenue that are of particular interest are those that indicate increased cracking and reduction in the effects of shear lag by the bracing on the column forces of an unbrnced tube structure. Results of sensitivity studies and the influence of the panels on lateral sdffness are illusmated by the deflection curves in Fig. 4.139. Evidently cmcking in floor members is very detrimental to the stiffness of unbraced tube structures (curvcs I and 11). but of only secondary importance in braced tubes (curves 111 and IV). The stiffening effect of the brncing is demonsvnted both in the reduced sway and in the modified-mode shape of the deflection curve (curve I versus curve Ill). The unbmced lube deflccts in a wallframe configuration, with concnvity downwind in the lower pan, concavity upwind in the upper part, and a point of contraflexure at about two-thirds of the height. The braced tube deflects in a more strongly flexural shape with a much higher point of contraflexure. The component of Lhe mbe's deflection due to racking shear of the columns and

Tubular Systems

S e c t 4.41

275

spandrels was, lherefore, reduced significantly by the bracing. This is further supported bv the small increasein the overall deflection when the spandrel stiffncsses are asigned . t i e large (50%) reduction to account for cracking. The deflection curve for the braced suucture with cracked bcams shows an increase in drift of 4% at the top, and a minimum increase of approximately 7% at about midheight. The maximum drift per story, however, which occurs in the middle region of the building, was hardly affected. The small influence on the overall lateral stiffness of the braced structure of a 50% va~iationin the moment of inenia of ihc spandrel beams indicates that their flexural stiffness, and therefore their depth, in the braced tube strucmre are of secondary importance. Their primary rolc is to nct as ties or struts in developing the axial forces in the intermediate columns. Figure 4.140 indicates ihc placement of the panel reinforcing. The column and spandrel bcam reinforcing was extended through the panel, which was also reinforced with lieht orthoronal reinforcements to minimize ihc size of accidental cracks. Collector reinforcing. suppicmunliog litc rpandrcl rcinforccmcnts, war added to i i ~ clop and buttom of the panel tu ;lugmcnt the lcnrile ruquiir.munts at the intcr,uctions Splicer an the m ~ i n rw~odrelrcinforu:mcsts aerc slaggurtd tu providc for lcnsilc forccr in the .p:!n~lrcl -beams. The construction of the concrete structure, from first footing to roof level, took 13 months to complctc. Thc building required 16.000 m' (21.000 yd') of concrete and 21 SO tonncs (2400 tons) of reinforcing bars. A 3-day construction cycle was easily maintaincd for the typical floors (a Z d a y cycle would have been possiblc with ovcrtimc). L

Direction ol force in diagonals

Spandrel reinfc. Collector reinfc. Column reinfc. Diagonal reinfc. Collector reinfc.

IV

111 II

--

HORIZONTAL DEFLECTION (fl) BRACED TUBE-UNCRACKED RFAMS - -- -- - BRACED TUBE--CRACKED BEAMS TUBE ONLY-UNCRACKED BEAMS (1.1

Spandrel reinfc.

-

Fig. 4.139

Dclleclionr olrlructurc.

Fig. 4.140

Urucing punel rcinfureirlg luseul.

276

Lateral Load Resisting Systems

[Chap. 4

Hotel de las Artes Barcelona. Spain

Architect Structural engineer Year of complclion Height from street lo roof Number of stories Number of levels below ground Building use Frame material Typical noor live load Basic wind vclocily Maximum lateral dcflcction Design fundemcntal period Design acceleration Design dantping Earthquake l o ~ d i n g Type of structure Foundation condilions Footing type Typical noor Story height Bcam span Bcom depth Beam spocing hlateri;~l Slab

Colun~ns Sizc st ground floor Spacing hlolcriol Corc

Skidmore Owingr and Merrill Skidmore Owings and Merrill 1992 137 m (450 fi) 43 1 Hotel Structural steel 2.87 kPa (60 psD 40 m/sec (90 mph) at 30 m (98 St) H/50O, 50-yr return period 5.2 scc Not applicnblc I % sensiccobility No1 applicable Diagonally braced lube in tllc form of mefa portal frames Dense sand Aufcred straighl sltnft piles construc~ed undcr bcntonitc slurry 3.00 m (9 it I 0 in.) Office 9.2 m (30 St) Orlice 157 mm ( I 8 in.) Office 4.6 m (15 ft) Sleel. A572, grade 50 75-mm composite metal deck 60-mm 12.4-in.) concrete + 55-mm (2.1 in.) sccand-pour concrctc

+

W350 by500 1bIf1inlerior: \\TA4 21 e h l e k r 9.2. 13.8 m (30. 45 St) A572 grddc 50 Braced lo p a n belr.cen mega brncing pencl points; rlcel-braced rrilrnes in orthogonal directions

The Motel dc las ilrtcs tower is the ,must prominent par1 of n multiusc cornplcx in

Barcelona. Spain. consislinf o i 5-slur luxury huteliapartment units. commercial oiiics space. retail. porkin.. and beallll club f:~cililics(Figs. 4.141 and 4.142). Thc project is

S e c t 4.41

Tubular Systems

277

278

Lateral Load Resisting Systems

[Chap. 4

luc3tcd along Barcelona harbor, overlooking the hlcditcrranetln Sea, and u a s colnpielcd in time for the 1992 So~ltmerOlgmpic G m e r The Hole1 d r 13s Ancr- i.;- o:tn -..of:$" -. - n,.p,. all plan to provide new infrastructure and private development of individual building parcels in the Olympic Village area. The lower is envisioned as one of the focal points in the reawakening of Barcelona as a major European capital.

..- .-.

Sect. 4.41

Tubular Systems

279

Continuing a long tradition at Skidmore Owings and Memll. thc uchiteclural form. crnression. and aniculalion of the tower a 2 all bascd on thc beauty and esrccnce of the expused, pninled stmclurol stecl fume. The archi~ecturnllyexposed X-braced framer located on the building periphery nrr organized on a Cslory [I?-m (39-R)] module. These frames form a fully three-dimenrianol iystern resisling nll wind and seismic 1atcr.xl forces as abortion o f t h e tower siavitv.load. o st he Full building inertia is uti. ~ .nr--well ~ ~ lized, n very eifici'ent lalcnl load resisting system is obmincd, with very lillle stecl abort that requircd lo resist the toucr gravity load. ueight From thr: archileclural point of view. a clear articulationof the cxtcrior slmclurc was desired. which is charactcnzed by the crisr, aro~ortionsof steel I b e a m , columns, and hilf-an .,. members. ~-~ . as well as the honest exbressfon of thc connectins ioints. both bolted 2nd ucldr.d.The cxtenor cunnin wail is set back 1.5 m (5 It) from the pcrimrler. thereby nrovidins n c l e u architsctural expression of the exposed X-braced slcrl frame. An open. ; e b l i k e ; ~ c ~ r e allowing the play of daylight through the frame, much desired by the architcctural design team; was-bainncedbythe need for robusmess and slructurnl integrity, particularly at the memberjoinls. Exterior frame members were chosen on the basis of erectabilily, connection detailing, nccessibility for slcel painting and future maintenance, and visual considerations related to the architectural aesthetic. The issues of corrosion and fire protection were addressed in engineering the exterior exposed steel fmme. Corrosion protection for the exposed steel members is providcd by a durable fluorocarbon paint system designed for long life under the coastal marine environment, consisting of a shop-applied primer, undercoat, and finish coat. with a sccond finish cont applied in the field after erection of the stecl frame. The nonfireproofed exterior structure was anolyzed using the latest slate-of-the-art fire engineering mcthods developed in Europe and the United States. Analytical methods to determine the steel lempcrnturcs as well as the charncler and nature of n number of hypothetical design fire events were stndied. High-tempernNre structural analysis of the entire huildine frame comaleted the fire eneineerins - desipn. A simple, straightforu,nrd architcctural cornpoiition expressing thc inhercnt function of the Slruclural frame, thl: Hole1 de Ins Ancs loner represents n prominent !\or),comhinine architccmre and ,uuctur~lrngincuring, marking a major intcm3Uonnl cclubration in Barcelona during the summerbf 1992.

-.

~

Fig. 4.142 Frurnvsurli: Holcl dc lur Art-.

280

Lateral Load Resisting Systems

[Chap. 4

PROJECT DESCRIPTIONS, BUNDLED TUBES Sears Tower Chicago, Illinois, USA

Architect Structural engineer Year of complelion Height from street lo roof Number of stories Number of levels below ground Building use Frame material Typical floor live load Basic wind velocity Maximum lateral deflection Design fundamcnlal period Design accclcration Design damping Earthquokc loading Type of structure Foundation conditions Footing type Typical floor Story height Truss span Truss dcplh Truss spacing Material Slab Columns Size at ground floor Spacing Material Core

Skidmorc Owings and Merrill Skidmorc Owings and Mcrrill 1974 443 m (1451 it) l I0 3 Omce Structural steel 2.5 Wa (50 p s 0 34 mlscc (75 mph) H1550. 100-yr relurn period 7.8 scc 20 mg peak. 10-yr relurn pcriod 1.25% scrviceabilily Not applicsble Bundled framed lubes 18-m (20-it)-deep steel-lined concrcie caissons Roft 3.92 m (12 fl 10.5 in.) 22.9 m (75 fi) 1016 m n ~(10 in.) 4.6 m (15 ft) Steel, grade 250 MPa (36 ksi) 63-mm (2.5-in.) lightweight concrete on 76-mm (3-in.) metal deck 990 by 610 mm (39 by 24 in.) built up 4.6 m (15 it) Steel, grade 350 MPa (50 ksi) Not applicable

The Sears Torvcr is the world's lellcsl office building with a height o f 4 4 3 m (1454 it) above ground (Fig. 4.143). It conloins 362,000 m' (3.9 million it') of oflice space in 109 slorics. The setbacks in tile facade result from reducing floor areas required by tenancy considerations. Sears. Roebuck and Company required large floors for their opcrotions, whereas smaller floors were best for rcnlal purposes. The adopted bundled tube concepl

282

'

Latsral Load Resisting Systems

[Chap. 4

provided nn organization of modular areas which could hc terminated at various levels to create floors of different shapes and sizes (Fig. 4.144). Each tube is 22.9 m (75 ft) square, and nine such tuhes make up n typical lower floor for an overall floor dimension of 68.6 m (225 ft). This square plan shape extends to the fiftieth floor, where the first tube terminnlions occur. Other terminations occur a1 floors 66 and 90, creating floor areas of 3800 to 1100 m'(41.000 to 12.000 ft21. The structurr: acts as; venicni canlilc\,er Lxcd at the hase lo resist wind loads. Nind square rubes of varying heights ;Ire bundled together lo crcale ihr larger ovcnll tube. Ench tubr comprises columns at 4.58-m (15-11) centers connected by stiif bcnms. Two adjacent tuhes share one sel of columns and henms. All column-to-he& connections are fullv welded. At three levels. the lubes incornorate trusses.. orovided to axial ~- m&e the ~~~column loads more uniform where tuhe.drop-offs occur. Thesc trusser occur hclow floors 66 and 90 and between floors 29 and 31. The two inarior frames connect opposing facade frames at two intermediate points, therehv reducing the shear Ian effect in the flanee frames. This reduces the oremium for hcigbt~onsidcr;~bly as shoun by the relnli\ely-lou unit stmctur;il rtccl qu;oli~g of 161 Lglrn' (33 pro. The uind-induced sway is nbout 7.6 mm (0.3 in.) per atory, and tltc fundamental period is 7.8 sec. The 22.9-m (75-ftl-square floor arcos of each tube are framed hv one-wav trusses spanning 22.9 (75 ft) i t 4.58-m (15-ft) ccntcrs. Each truss conneci dircctly'to a column with a high-strength friction-grip bolted shear connection. The span direction o r these 1NSScs was alternated every six stories to equalize gravity loading on the columns. The tmsscs are I020 mm (40 in.) deep and utilize all of the available depth in the space between the ceiling and the floor slab above. The spaces between the diagonal truss wch members allow the passage of up to 530-mm (21-in.)-diameter air-conditioning ducts. Benms and columns are built-up I sections of 1070- and 990-mm ( 4 2 and 39-in.) depth, respectively. Column flanges vnry from 609 by 102 mm (24 by 4 in.) at the hottom to 305 hv 19 mm (12 hv 2.75 in.) at the too. and henm flanres from 406 bv 70 mm (16 by 2.75 k.)to 254 by mm (10 by 1 in.j. A total of 69.000 tdnnes (76.ion tons) of structural steel was used in the project, consisting of grades A588, A572, and A36. The steel-tube structure was shop-fabricated into units of two-story-high columns and half-span heams each side. tvoicallv weiehine 14 lonnes 115 tons). The shoo fahrication climinatrd95560f field uelding. ~ u t o m a t r d r l r c l r o s l aweldini ~ was usedior thc hull aulds of hcnms to columns. The continuity plates ocrors columns at the joints ~ c r c fillet-welded by the innershield process. Because site storaee sonce wns unavailable. the frame units were delivered exnctlv when needed and lift&! oif the truck into place. Except for column splices, all field con'neclions were grnde A490 high-slrength friction-grip bolts in shear connections. Exterior columns were insulated to limit the average temperature differential between these columns nnd interior columns.

.

~~~~~~~~

.

Sect 4.41

r

..

b "7

N

3' cellular deck

N

I1

21/2"

D

'ul r-

z

m

Typical lraming plan (levels 1 lo 50) (a)

Li5

..

.

283

Tubular Systems

-

Modular lloor conliguralion (bl Etg. 4.144

ScorJ Tower.

It. wt. cond

284

Lateral Load Resisting Systems

[Chap. 4

Sect. 4.41

Tubular Systems

Rialto Building Mdbourne, Australia >,.'.,

Architect ..... .. . ,

. .

Structural engineer Ycar of compiction Hcight from sUcel to roof Number of storles Number of levels below €101 Building use Frame nlatcrial ~ y ~ i cfloor a l live load Basic wind velocity Maximum lateral deflection Design fundamental pcriod Design damping Earthquake loading Type of strucmrc

Shear lag behavior

F ~ R4.144 . Srnrs l'cmrr. ~ C ~ ~ n r i r , , , ~ d ]

Foundalion conditions Fooling type

:-,, .

g; ?t:

,?I; ,.*a

2. ..?. rt :,z

s!.

.< ,.,: L.

.-

"~:

Typical floor Story height Beam span Beam depth Bcam spdcjng Slab Columns Size at ground floor Spacing htaterial Core hlatcrial

I

~ e m r dde PrcuPenott Lyon Mathieson Pty. Ltd. Meinhardt Australia Ply. Ltd. 1985 243 m (797 fi) 63 2 Office Concrete 4 W a (80 psfl 39 mlsec (87 mph). 50-yr return 230 mm (9 in.). 50-yr return 6.1 scc 3% serviceability: 510 ultimate Not applicable concrete core with concrete perimeter frames ~ a s a l tover sands and clays over mudstone Caissons 1500 or 1800 mm (5 or 6 ft) in diameter. 18 m (59 ft) long, socketed inlo rock 3.9 m (12 f 9 . 5 in.) 10.5 m (34 ft 6 in.) 500 mm (20 in.) 5 m (16 ft 5 in.) 120.mm (4.75-in.) lightweight concrete 1.2 m (4 ft) octagonal 5 m (16 f t 5 in.) Concrete. 60 MPa (8500 psi) Shcar walls. 750 mm (30 in.) maximum thick at ground floor Concrete. 60 MPa (8500 psi)

A number of structural systems for the Rialto Building (Fig. 4.145) were initially investigatcd and a reinforced concrete swctural system was finally adopted, with speed of construction being a prime consideration in the dcvclopment of formu,ark and reinforcement dctails

:>,

.2,: ;.

Lateral Load Resisting Systems

Sect. 4.41

Tubular Systems

The external frame or coluntns and beams, urhile being designed for the direct dead and live loads aoolicable. acts as an external tube i n resirtine lateral load. Althoueh the plan shap: i r uns)t~t~aetricaI 3ad tltc colutons arc 5 m (16.4 i t ) apart. ;lnaly$is 01 lhu i n ~ d tmnsfer ardund the uurners indicated re>runxblc thrce-din1:nsiunal action. l h l : corner beams connecting the end columns are most oecessary for Lhis action. The tube effect also provides forsome latcrnl distribution of load from thc more heavily loadcd columns (Fig. 4.146). Thc service cores, being the major elements i n the structure, were the subject o f a number o f detailed considerationr. No sizable penerrations or rebates were permitted i n the main walls. Sizine ofthe walls was not oolv for Iondine considerations. but !v\'as the suhjcct ofrhrinkngc 2nd 2rr.r.p usti~natiun~ 2nd r~.fiocmcntfor buildlng pcrfornlsncr.. F i n d checking afthc intcrnctillc corcl rind r.\tr.rn;jl frames u.2~cxried out using n tl>r~.i.. dimcnrionxl l i n i t u - ~ I ~ . , l ~on:~l)sis. snt Design u i n J 102ds i n th? b.ulding wcrc calculated ~ ~ i mctcorological n g d313 3s13ilz~hlc.Thc huil~lingi r of S L C ~3 beigttt, rile. 2nd s l e e d ~ r ~ ~ that ~ aths s diifr.rcnt : ~ p p r u ~ c h tclocitiu* 2nd wind dcrcctiurl, nurr qignilicant ~n the dciig~t.\ \ ' i d tunncl tsats dutr.rmlncd design prcssurds 10, hoth the iruilding ;and the facade. Frntn thc north, elst. and rvrrt. terrain category 4 (1.36 applicable. ~ l t i l c[ram th~.south, with Port Phillip R3g bein^ 3 k m (?, . mi) distnnt. tcrrain~cnteeorv - . I was considered above level 30 Tlic i;,icr>l projcctirm of thc h ~ ~ l d i n being g, s.ynmctric31. inducer 3 $rind fnrcc un n.ll >luj!s cnnfc,rrn a1111lhs c ~ n l e ruf J t i f i n ~ s rTi16 . pr,r1111dlr.r thc s t r ~ c l t ! rt~h ~ t bcnms and cores have bccn modilied to align thc ta,o centroids as closely as possible at all lcvels: homevcr, a section of tllc building between levels 24 and 40 is subject to a twisting force. Thc calculnted drift at the top of the tower undcr maximum design wind forces and incorporatina this twisting i s 230 m m (9 in.). A major consideration addressed and rcrolved early i n the design phase was the aspect o f shrinksge and creep o f lhc concrete structure. Most buildings of [his size r\,orldu,ide are steel framed and not subicct to these tvocs of mo\~emeots. ,, .An nsaussmeol i,i111~1C I :xnd ~ shritlkagl: U VL.~ICII I ulemcnls in llic prujecl $$asc:lrr i ~ out d i ~ r ~ h i use n g uf rurcar:lt dht3 i l v ~ i l btcurnlhe l~ United Srille~.USL~~LLI?~~:C \;$Iucs derived for material properties and predictions wilh regard to weather and building orouram. a comouter .oroeram was deselooed taking = = into account member size. concrete str~.ttgth,r:inforcr.m~.nt ratio, age ;I 1o:iding. I~umidtty,loldittg condit~uns.and cre:p and sIirink3g~.d~velopm~.nt. I t N ~ anticip:~tr.d S th;it thc total nonelartic .~hon~.nisg oithe 65storv to& would be on order of 1% to 200 mm (6 to 8 in.). Provided allowances are ~itsdei n tlte atlachntest of non-ln~d-bu3rinb ciements such its l ~ frt~ i l atid s the faode, the magnitude u f l h i r nnnvlastic dsform;~tiottis ttot i i g n ~ i l c i n t .HU\I~\L.I, cliff~r~.nccs i n tltc msnilude uf ihnnkage ;md crsup inirltirt :1 1x11 concrete structure 15 3 ntajur .ulljcct n f concern, and this is p&ticularly rclc~,anti n the case o f the Rialto towers. Lone-term differential shortenine bcr~veenthe central core and nerimelcr columns at the top of a typical tower building can be readily catered for as the distances between thcsc elements are usually large. Thc combined shrinkage and creep lo be expected after construclion of the upper levels o f the Rialto lO\\.er5 indicntcd differential rnlucs of 10mm (% . .. in.). i n thecase o f towerB and 1 1 m m (% . . in.). i n thecascofto\verA.Thc mini m ~ nsp:~ns l i n ~ n l l ~r c~9.7~ 01 d ( 3 2 11) 2nd 7.0 i n (23 it), r-sp:cli\ely. I-lot\c\r.r. o * tun d r i \ 2nd B furm a n intugr~tr.ditruclurc. 3 differr.nti:~l\i~lul:un the urdcr of 38 inn1 (1.5 in.) could he -.\PL.CIC~ bct~ee11 >di;lc~.nlc ~ l u t ~ l ill n r I~.!el -41 (IoNL.~ B rnnfj ~ U L . 10 effects o f the addiiional I 7 levels o f k w e r A. The distance between these columns is only .I111 (13 ft). ;~ndclcnrlg ru;h inotcntcnt, u:tn~tut hu tolr.r3tsd in a ~ o n s t c ~ ~ cu ti ti t~l inr !lalore. Jointing oflltc t u ~ c r se l r not 3ccepli~hlc.2nd tlte ~rovisiortnfi!.'h:lt"xt this l e \ ~ 1 was unsuitnblc to Lhe architecture, as !,,ell as inducing a long-term out-of-plumb ofthe top o f tower A.

..

-

~

.

-

Fig. 1.115 Riulto Building, hlrlbuurnc, Austmliu,

287

.

-

288

Lateral Load Resisting Systems

[Chap. 4

S e c t 4.41

Tubular Systems

289

The solulion arriied at uas to "play a cunfidcnce lnck" on lo!rer 5,nlabng lhe structure '.bcliwc" it is 17 slorics Inllur. Prcrtrcrsing cohles are provided from lcvel I to level 38 and stage stressed as tower A conslrucdonproceeds. Thereby nll columns below level 38 are subject to the same loadings at the same time, and therefore elastic and nonelnstic shortening values are relatively consistent for the lifetime of Ule building (Fig. 4.147).

Fig. 4.147

Fig. 4.146 Fluor pions; Riallo Uuilding

SLnged slresring; Rlnlla Building.

290

Lateral Load Resisting Systems

Tubular Systems

N6E Building Shinjuku-Ku, Tokyo, Japan Architect Strucmnl engineer Year of completion Height from street to roof Number o r stories Number of levels below ground Building use Frame material Typical floor live load Basic wind velocily hlavimum lateral deflection Design fundamental period Design acceleration Design damping Eanhrluakc lr~ading Type or structure Foundation conditions Typical floor Story height Beam span Beam depth Beam spacing Slab Columns Size at ground level Spacing Core

Nihnn Sekkei Inc. Nihon Sekkci Inc. 1996 189.6 m (622 it) 46 4

Offices and retail Stccl 5 kPa (100 p s n 35 mlsec (78 mph) HtZOO. IOO-yr rctum 4.56.4.75 scc 35 mg pcak. 100-yr rcturn 1% rcrviceability; ?% uldrnate c = 0.0533 Dundlcd tube Clay and rand o\,eigravrl 3.95 n~ 113 ft) 19.6. 16.4 m (6-1 f t 1 in.. 53 it 10 in.) 800. 600 mm 131.5.23.5 in.) 3.2. 3.6 m (10 fi 6 in.. I I it I0 in.) 135-mm (5.15-in.) reinforced concrcte 600 by 600 mm (24 by 24 in.) 3.z.3.6 m ( I 0 Cl 6 in.. I I It 10 in.) Fremcd tube

The plan dimensions of the N6E Building ore 92 by 39.2 m (302 by 128 it), which is quite large (Fig. 4.148). The core location caused eccentricities that could not be rcduced using shcar \raallsor bracing systems, so the bundled tube r).stcm was adopted to ochicve a symmetric structure and lo avoid torsional problems (Fig. 4.1491. This mas done at the expense of reduced span lengths and incicased numbers ofcolumns. The building response was estimated using ail available data as well as the alongwind and cross-wind power spectra end cospectra, which vary with the building heighL Ail cslculetions were donc forl: J. and lorsional directions.

Fig. 4.148 NGE Building, Tekyo, Jupnn.

Lateral Load Resisting Systems

[Chap. 4

Sect. 4.41

Tubular Systems

293

Carnegie Hall Tower New York, N.Y., USA . :.. . 2,: L

Fig. 4.149 Typical structural plnn; N6E Building.

Structural engineer Year of completion Height of street 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 Design damping Earthquake loading Type of structure Foundalion conditions Footing type Typical floor Story height Beam span and spacing Beam depth Slab Columns Material Core

I

C e s u Pelli and Associates (desim) Brennan. Beer, G o m a n Associates Robert Rosenwnsser Associntes 1989 230.7 m (757 ft) 62 I Office Concrete 2.5 kPa (50 psf) 47 mlsec (105 mph). 100-yr rcmm period Approx Hl500. 100-yr return 4.8 sec E-W; 3 scc N-S: 2 sec torsion 20 mg peak. IO-yr remm period 1% serviceability: 2x7'0 ultimate Not applicable Side-by-side concrete tubes Rock. 4-MPa (40-tonlft') capacity Spread roolings 3.66111 (12 ft) Vnrying 457 mm (18 in.) interior; 762-mm (30-in.) spandrels One- and two-way, 230 mm (9 in.) thick Size and spacing vary Concrete. 58 MPn (8400 psi) S h e u walls ( p u t of tubes); thickness varies; concrete as for columns

At 230.7 m (757 11) in h?iphr. Camepie IJall Tosser ia the iccond 1:~llestconcrcle rlruclure in N r u York Cily and thssighth tollssl in the wnrld ludly (Fig. 1.150). With a 15.2nl (50-TI)-ulde~nnnllTdce and 1 2?.9-m (75-r1)-wide south race. which olfsc.1~lu a 15.2m (50-it) face above the forty-second floor, this 62-story SlNClUrc is the most slender habitable building of this height ever constructed (Fig. 4.151). The structure occupies the narrow site bctween the five-story Russian Ten Room and the 100-yeor-old Cornegie Music Hull. The structure's nrchitect. Cesar Pelli Associates, dictated the structural scheme by "sculpting" the structure to complement the existing music hall. The double (side-by-side) tube structural system that resulted rvss actually defined by filling in all the available spaces bctmeen the desired windows with concrete. This resulted in nonuniformity in column size and spacing.

I i!

Lateral Load Resisting Systems

Fig. 4.i5U

Curneglc Holi Tower, KEIVYolk.

[Chap. 4

Lateral Load Resisting Systems

296

The nonuniformity in the size o f the columns at a level was also extended venicolly as -~offseu -~~~~- and larecr or -~ smaller window sizes dictated relocation or alteredcolumn sizes. Often Viercndcel nction u,as nerdcd to terrninntc venical eletncnls at vlrious locations without the benefit of trnnlfer girders. This occurred on the nonh and south walls and above the fortv-second floorrif the south half of the west wall, which spans over the enlareed haze: Vicrendcel action was also reauired direcllv above lhe ihroueh-block plrjags at the ground floor and at sevcral othcr localions. A center u r b (perforated by lobby egress requirements), common to ihc1u.o side-byside tubes. w m needed to heln Ule north- and soulh-wall columns to efficienllv connect l the C ~ S I nDngc. wall to l c w&t flange wall with minimum shmr lag. A ~ l e r c n d e ecolumn (skipping alternate floors to minimize the lobby obstructions) u,as introduced to rcducc the clear span u f ihc center wcb. This Vicrcnducl column i s the only intcrior culumn i n the stru;ture. which othewisc s u. .o o o ~dl rrnvitv loads b v thhexterior tube uolutttns and t h ~~. . I e v a l n r c o rwi!lls. ~ The large c l x r spms o f 9.1 m (31 it) and more bc1,vccn the elevator core and tlic u c r t wall wcrc spanned wllh 230-mm (9-in.) slabs nnd shnlluu beams ,157 mm (18 in.) deep. This f r a n l i n ~for gravity loads proved to be [nore economical than one-way ioisu; o r w a f f l e slab coislruction bccausi i t orovided more mdss to rcsist uplift forct~s?rolnwtnd loads and to reduce bullding acccl~rations.I t also pro\idcd c x t n height to accommodate mcchanic:,l systems so that with 3 lutal slog. height 013.66 m ( I ? it). 3 ceiltng height o f 2.7 m (9 i t ) uas maintained. TIISdouhlc tuhc design relics hcavily on 760-mm (30-in)-deep spandrel beams to tnpage 211 tltc vcntcnl suppuns to rcsist thc rxind actio~iand to equalize the SI~L.SSCS due to gravity l o ~ d si n all suppons rugardlcss ofthcir smr. The tube's venical rttcmhers vari t d bstr\,cen l R O and 2590 mm (19 and 102 in.) i n length (parallel lo tltc cxtcrior) and included a solid concrete wall behind the service core &a to the cast. The structural design cnnsidcrcd hoth the relasation duc to long-tcrm crccp and 5hrinkagc ofthe concrew mumbur, dnd the instnntaneous demands ofthe wind iurcer. Ennugh gmvity loads % v ~ . r:lassmbled r. to clitninatc the possibility of tension duc to wind in the vertical supporn and to ict the gravitational loads anchor the structure. A few rock anchors at the west end o f t h c center web were added to enhance the vbilitv of < -~ the web l o cngspc llie flanges cv6.n under larger lateral loods than dicvatcd by the Nerr York City cndc or the wind tunnul ru,ults. 'lllc prelintinary design considered both steel and concrete. Conuol ofthe ourceotion of motion w i t h o u i a u x i l ~ mmeans such as damoers was found to be nttainableonlv -- - ,with --.. tit: concrete allerrtalivc because of ihs larger damping 2nd weight of a concrete stmclure. H u ~ c v L . ~1S. a prt~iluliun.because o f its extreme slendcmcss. the stlucturc was dssigned to accommodate a pendulum-type damper. Field meaurements, after the structure was topped out, indicated that dcsign predictions were accurate and n damper was not needed. The anticipated accelerations, projected from these load mcnsurcments. should not exceed 20 m g for the 10-year return pcriod. Concrete was pumped i n to the full height o f the structure. Concrete strength i n the columns did not exceed 58 MPa (8400 psi) because the use of silica fume i n New York City was still questionable at the time the structure was designed. For this and other slender structures, stiffness, weight. and damping are the important parameters diclating the slructurc's behavior. The design for acceptable perception o f motion oRen ovcrrides othcr more mundane design requirements such 3s strength and stability.This aruclure together with its earlier slender siblings (Metropolitan Tower. Cityspire, and the Concordia Hotel) ore prototypes of the future mcgastructures of the neat generation o f I d 1 SLIUCLUres.

-~-

~~

Sect. 4.41

[Chap. 4

-

~

Architect .Y.*::.:,h Stru=tuml engineer

Skidmore Owings and M c r r i l l

Year o f completion Height from sueet to roof

1983 296 m (972 it)

Number of stories

71

Number o f levels below ground

4

Building use Frame material Typical floor live load

OlEce

Maximum lateral deflection Design fundamental period

Not available

Design acceleration

Not available

Design damping

I% serviccnbility

Earthquake loading

Not applicable

Type o i structure

Pcrimeter framed tube; diagonally braced core with outrigger trusses Stiff clay

Foundation conditions Footing type Typical noor

~~

4.0 m (13 i t 1 in.)

Bcam depth

530 mm (21 in.)

Beam spacing

4.6 m (15 it) Steel, grade 250 MPn (36 ksi)

Slab Columns

Spacing Material ' i .

Mat 2.9 m (9 f t 6 in.) thick

Story height Beam span

Material

1:~. ~-:

Skidmore Owings and M e m l l

Stmctural steel 2.5 W a (50 psO Unavailable [force = 196 k N l m (13,400 Iblft) for 100-yr rclurnl H/500. 100-yr return

Basic wind velocity

. .

~

297

Allied Bank Plaza Houston, Texas, USA

~

-

Tubular Systems

core

15.2 m (50 ft)

83-mm (3.25-in.) concrete on 76-mm (3in.) metal deck Built-up. 1016- b y 610-mm (40- by 2 6 in.) pcrimctcr: 610- by 610-mm (24- by 24-in.) interior 4.6-m (15-ft) perimeter: 9.15- b y 6.1-m (30- by 20-it) intcrior Steel, grade 250 and 350 MPa (36 nnd 50 ksi) Braced steel frame, gradc350 MPa (50 h i )

%..

3.22

h

:I<

?!:

,:2.

:$ .*., 4: ;?2 ~:&:

&?. *P~

Allied Bank Plazn was designed to relate strongly to the buildinps around it. Situated on a site which is essentially the center oldowntown Houston, the building has a major tmpact on the western iacadc ofthe city; which is the most dominant view of its skylinc. In form and mnterials, a design was sought which would be distinctive but would Scr\pC

Lateral Load Resisting Systems

298

[Chap. 4

to complement and tie together its surroundings. A form that tnovcd and flowed was felt to be nppropriatc, one that wns sort and sheer rather tltan 1t;lrd and opaque like the granite and steel rectnnnulnr buildines around it (Fie. 4.1521. The resulting semicurved lower was uchievcd by juxtaposing two quarter-cylindcr shafis (Fig. 4.153). The 71-story tower is sheathed in dttrk green rcflccdve glass, chosen for its sheer quality and rcsponsivencss to light. Tite combination o r p l a n s and curves in the building's design will allow a cconrtant intcrplay of sunlight un its surface.

-

-

-

Sect. 4.41

Tubular Systems

299

Givine" the buildine a human scale was another imoonant asoect or the desianer's intcnlions. Unlike many recent buildings, which are sheathed in reflective glass and appear only as a huge mass. the swcture of the Allied Bank Plaza is subtly cxprcssed with venical&d horizonml mullions. A formal o o m l on theeastsideoflhe b$ldi"eorovides asense of cnlr).. Slncc h5rc or the public u n e r r the tun~~el-cotittccted dounloun buildings st the underground lcrel. Allied Bank PICA o l r ~ r st l i ~olily entnnce directly from the SU~L.Iand combines the tunnel with M open-air plaza, including landscaping and a fountain. A bundled tube frame is the ~ r i m a r vlnrcral svstem for the 71-storv 296-111 1972-ftl1211 186.OUU.m' I? mtliton 11') .iilisd 63nk lorie;. The shape is forme> by luo'quanr;circlcs placcd ~nus)mmctricall! bout thc m ~ d d l ctuhulir line. Tiis colun~nsp~cing5brc 1.57 m ( l j it) \kith the usuil tres-l)pe construction. Thc systcm ilso uses irvo v~micll trusses in the core, which are connccied to the exterior tube by outrigger and belt wsses. Sienificant imorovemenl in tubular behavior is obtained bccause o r the oarticioation of the INSSeS. This sysrcm, thcrcrorc, embodies elements from the framed tube, bundlcd tube, and truss rystcme with bcit and ouvigger trusses. The truss system provides another transverse frame linkage in the curvilinear part to improw its shear lngchnrnctciisticn. The structurai system for the Allied Bank Plaza towcr was sclcctcd after study of both steel and composite systems. Tite system permitted a substontially reduced cons w c t i o n time. The tower's form and slcndcrness arc a radical departure from past rcctnngularbuildings of this height. yet the inherent rigidity or the bundled tube system dcveiooed for the tower limited stccl w c i ~ h to t 128 ke/m2 126.2 nsn. b

-.

-

cant reductions in design wind pressure belorr' that experienced by square or rectangular rorms. The tower is founded on a 2.9-m 19-ft 6-in.)-thick mat roundation aooroximalely 20 m (65 ft) below grade, which pc;mits utilization of four lowcr lcdels for necessary retail, mechanical, and parking lunctions.

Fig. 4.151 hliird Unnli I'inzn. Hoartun, Tcsits. tPbrlio I?HedN'rS-Blcrriag.1

Lateral Load Resisting Systems

300

[Chap. 4

4 ~ 5 HYBRID SYSTEMS

Tall buildings hdve been lraditionllly designed lo n l o k use of 3 rlnglc type uf Inlcr~l In3d resisting system-inttially s ~ m p l cmoment resisting frames 2nd then shcar wall s\,rtcms and frimed rubes. Until ~ h radvent . of economical, c3sy-lo-use. high-capacit) cbmouter hardware and software. structural svstems had to be amenable to hand calcuI;ttioc or cumpuler a n ; ~ l y s ~usit~g s limitcd-c:tpacity nlach~nts.Notvnda).~computcr capacil) l s nu1 ;an issue, and decisions on slructural syilcms art made on 1h~'basisof1h:ir r.ficcts on the xppcdrance and funclioning of the building and on its cnnaln~ctahil~ty. This is not to sieeest that on,*l/~i,in~ musl still be aware of . " is nc&otable-lhe e&ineer 111,: pi1p~II5 ofcrc3ting ;~bruptdiscnntimriticr in building sliffncrs. the Ions-tcrm cffecls nf dilf:rcntial ixi31 siloncninp. and other side effccl, of using mired systems and multiple materials. as Bank Center in SinAn excellent examnle of a hvbrid svslcm is the O ~ ~ e r s eUnion gdporc. Here :.b r x t d stcvl fr:,n:c rvas used b:causc ofils lightnos. lnng sp:inniog ihd. )I!, small metnbcr aizss, absence of crccp shancning. and. combined with ioncrcle a h e ~ tralla. r for iL\ r c r \ cost.r.fficicnt contribution to l>ltral stiffn~ss. Another tvoe of hibrid svslem " eaininr! oooulsritv is the concrete-filled steel lube , column, u.berc lhe r.rcct3bility of n str.ci framr: is 111iinlaincd.but the c o s l . ~ f f c c l i ~3 ,~- c i;! In-d uapacily ufhiglt-rlrcnpth concrete is u ~ e dThe stecl tube pruvidcs cunfincmcnt lo the concrelc much more eificiently than normal reinforcement does, and it is on the extreme outside. where il is most effective. Of course fire orolcction must bc considered. If the slecl tube is considered ns sacrificinl in a fire, then inlernal reinforcement sufficient for the reduced loading normnlly prescribed for the fire limit state must be provided. If external fire protection is provided, lhcn internal reinforcemcnt may not be needed. If concrete can be oumocd into the column from ihc base of each Dour. then a number ofstorics can be concreted at one time and vibration of the concrele is not necessary. Examples of such a system are Cnsscidcn Place. Melbourne, and Two Union Square. Seattle. The rrends of modem architecture sometimes force the structural engineer away from convention in a search for a struclure that will nccommodale ocsthctic and functional demands while meeting struclurnl requiremen*. The result may be a structure which on one face of the building is of a different type than the other faces, as in Georeia Pacific. Atlanta. or a S I N C ~ U ~ ;with a number of quite different clemenls formine i s Lateral load resisling frame, an exccllenl example being First Bank Place. ~ i n n e a ~ o l i s . Here the engineer has provided a braced steci core connected via outilggcr beams to large high-strength concrete perimeter columns, incorporating cast-in fieelwork lo aid erection and connection. Although this systcm provides in-plane stiffness. its lack of torsional stiffness required that additional measures be lakcn. which rcsultcd in one buv oi tr.ruu.ll cxterior hr:lcinp 2nd ;i iturnher ui l:vcl. of pcriln~.lr.r\'lerc,dr.cl 'b..oJ.iges."-pr.rl~aps unc of lhr h~.rtcaamplcs of the an uf$~ructuralcngin~'rring. Wilh t l r adtctll of high-r~renglhcottcrcle [uuncrclc ;1buv~'50>!PAor (70UU psi,] 113, come ihe era of the "sipcrcolumn." where the stiflncss and damping cnpabjlities of larre concrete elements are combined with the liehiness and conslructabilitv of stecl li:unus. I-l~gI~-r~rungtlt uortcmte. \$hen 11 irlclrrdu, silicz fumc ;mi 3 high-rarrge ivu:,nlr,oriorl Engineering Ncwr Rccord 1988. S.vdncy Slycrnpcr Serr Soil Engineering News Record 1989. 19.000pri Enginecring Ncwa Record 1990, btnoi,ori!,cTecbm'qlte> Engineering Ncwr Rccord 1991. Sydnry Toa,er Tertr A~lrfrolior~r Gcorgc 1990. Ii'ullirrgron'r IYiiid~Slirrpedthe C~~pirol', Tollert Bm,ilding Gillcrpie 1990. Derign and Co,zsrncrion oJSrn.1 Fronted High-Rire Blriidirrgs Grorrmnn 1985, 780 Third Atrenae, Tile Fin, High-Rirc Diagortolly Broccd Corrcrelc Sln,cf!8rc Grorsmnn 1986. Beliovior. Analysir orrd Corzrrr#ccriar~ ",fa Braced-Tube Conrrele Slrrrclt,ru Giosrmon 1989. Slender Smacnwes-Tlze Nc!v Edgc (10 Grorrman 1990. Sloider Carrcrere Sm,cfr,rrr-T18r New Edge Howillcur 1992, Dedgn oJrbeNorionr Bonk Corporufe Crnfcr Horc 1990. Srnrcrrrrol Design for rlre Riolro Towerr lloh 1991. 1Vind Rerisranr Derign oJo Toll Bl,ildi#tg ivi~irm N l i p ~ ~ i d Crorr o l Seclion Journol o f Wind Engineering and lndurtriol Aerodynamics 1990. Oprinii.~afionoJToll Bltilding* Jor lVittd Loading Kunemc 1985. Deep Coirron Fo~~ndofianrJor OUB Cerrlre. Singnpore Kuneme 1990. The OUB Centre Tower Folfndoria,rr. Sirtgopore Meinhvrdt 1981. S~8perrrrucrureDc~ignJarllzc O\,rrreor U#iiorzBonk B,,iiditcg. Si,,gll~lore Mcinhurdt 1990. Tire 008 Cmrre-Qnolig Deil>,eqs Melbourne 1985. Aerorlostic hlodel Tenr ovld Tl~eirAppiicorion jor rile OUB Ccrifre.Si8tgnporc Plnllcn 1986. Porrrtiodurn Engineering Plotten 1988. h f o ~ r ~ r ~Plocr: ~ r ! ~ ~Sleel t l Solvcr Co#!!plr.cGeon!vfricr Tnrnnth 1988. Sfrircf8~rnl Anolyrir orld Dcrigr! qfToll Baildir~gs

5

-7...*

-

Special Topics

5.1 DESIGNING TO REDUCE PERCEPTIBLE WIND-INDUCED MOTIONS 'She 3 ~ r ~ ~ c ~>!stem\ u r ! l Sor la11 h.~il,Ii~~;,3rd murc d l c n cun~r~>llcd I>> 11,c need 10 r:.lriein sr ind nction ;)I ~ c r ~ i r u ~ h iIc>cI\ l ~ t y 111:,n the nsu.1 tn pr,nidr. riruand 3 r c r ~ gd-n\it).-ill ~. olller srurdr, ms*-

.

-

Fire Protection of Structural Elements

Sect 5.21

353

b. Accrlcration is proporlional to lltc square root 01the lorcc spectrum coellicicnt C,, and this is where paramclcr dependence bccomcs cnmplicaled. With relercnce to Fig. 5.1 it can bc noted lllat CFS,l o r a_fii.cn building gcamclry, is cx, ;pressed as a lunction nrreduccd velncily 1'" = V,lr,,b and that C ,, increases wilh

y>

V, up to a peak tltis range covers most applications. This implies an additional direct -~~ dcoendcnce on wind soeed. which makes thc accclcralion dcpendcnl on somethink approaclling 10 over this region. Also thc increased size dcscribcd by building width 6 reduces V.. nnd llence C,:,, which also works to reduce acceleration nddilinn to the n;bssivcncss clfict. Howcvcr, this size increase also moves to reduce frequency and hence increases V", and also C, and accelcration. c. hlodest rounding or chnmlcring orcurners (10% 01widdt) docs no1significantly rcducc serviceability accclcralion lcvels, although a significant reduction in ultimate lirnil-state momcnls cun be achicvcd. More significant comer roundinc or chamlcr-

.

in

relative to that Tor a square, sharp-corncred building is rcasonsbly ochicvnble. O v c n l l the eliccts o r irequcncy, building density. l t c i g l ~and l \vidth, and planlorm shape are so inrerrclalcd that it is nnly by the typc arcvaluation shown i n Fig. 5.5 that an appreciation or lhese aspects can bc uhtaincd.

a

t

1-

I

square building, sharp corners

-----

--

square building, chamfered corners (-0.1 b) rough circular, oclagonal or tapered building

5 Conclusions The excitation mechanisms \\,lliclt csusc the most pcrccplible motions i n tall buildings havc bccn dcscribcd. nnd il has bcen shown tIt;i~ thc cross-wind rcsponsc i s (he domin:mt cnusc o f motion ocrccotion nroblclns

a pirameler scnsiliaity discussion, wilh worked examples, has been presented to give a desiener some indication 01how lo avoid lhinh " acccleration levels i n loll buildings, and so avoid the need for auxiliary dnmping systems. In particular il was shown that very tall buildings arc not necessarily the most sensiliue i n terms of occupancy comfort, but that souareTsham-cornered. hieh-aspccl-ratio tall buildincs are likely to have accclera- . tion p;oblems an.d that thcsc can be avoidcd by using p l a k r m shapes with cul corners approaching n circular shape. tapering with height. increased mass, and structural systems which straighten up the first-mode shapc. b

+=recommended

I

criterion

-

5.2 FIRE PROTECTION OF STRUCTURAL ELEMENTS The slruclunl system adopted for a building. including lhc choice of construction materials, is ohcn strongly influenced by ihc fire resislencc requircmenls o f building rc€ulations and codes. Although building code requirements with respect to lire vary between countries, it is gcncrally accepted that buildings should bc designed for the limit svatc 01fire to achieve tllc follor\,ing objectives: building height, m Fig.55 hlasimum shndord dcriulion urcclcmllll_nfar I0 lnin In 5-scar rtlurn period for nrrluu rsnogumtiunr; 5 = 11.111; ps = I60 kg/m'; V,,= 12 (hNOOl"J'; n = 4611,.

1. Providc an nccepl.able level o f safety l o r ihc building occupants and limfighters. 2. The adjvccnt propcrty is not dnmugcd.

354

Special Topics

[Chap. 5

The level of safety offered to the occupants of a building in the cvent of a fire is a complex function of numerous factors, including: I. The likely chnmctcristics of the fire 2. Thc likely behavior o f t h e occupants (whcthcr they are alert or asleep, their reactions) 3. T h e likely pcrformnnce ofcompartmcntation with respect to rcsvicting the movcmcnt of smoke and flames 4. The likely pcrformonce of early \\wning systems (if any) in notifying the occupants 5. The performance o f t h e sprinkler system ond smokc control systems (if any) 6. The response of thc firc brigade All o i thcsc factors arc probabilistic by naturc and functions of time. Time is of the utmost imporlancc in designing buildings for firc safcty-it being important thnt succcssful egress be achic\,cd bciorc conditions become untcneble in the fire compartment. A systematic approach to dcsigning buildings for fire mfety needs lo take into account all ofthcse factors from a probabilistic approach and lo recognize the importance oftime. In contmst to such an approach, tllc regulatory rcquircmcnts with respect to fire safcty that have evol\~edin many countries gcncrnlly represent an ad hoc and unsyslcmatic approach to designing buildings for fire safcty. Buildings arc rcquircd to be dcsigned such that the structural mcmbrrs possess a ccrlain fire rcsistancc as dctcrmincd in accordance with the standard fire test-a test that generally bcnrs littlc relationship to real fires and takes no account o f t h e time for fire dc\,elopmcnt :!nd sprcnd. But it is a useful tcst in that it allows the fire rcsistancc of clcmcnts of construction to be n t c d on n relative basis. Littlc account is taken of the types ofacti\,itics taking place within the building, and generally little provision is made for the reduction of fire resistance requircmcnts due to the presence of other components of the fire safety system such as sprinklers, smokc detectors, and more cflicicnt egress provisions. However, it is likely that in msny silustions the application of a systematic approach to assessing the fire saiety of buildings will allow a substantial reduction in the level of the fire resistance required for membcrs-without resulting in any decrease in fire saiety. T h e purpose of this section is lo consider how the structural form of buildings may be influenced by the need to design for fire safety. For a thorough consideration of 19921. fire snictv in tall buildinrs. scc Fire Sofen, , . irr Trill Btrildin~s ,. (CTBUH. . r11 the outist i t nr.r.d. to hc $l:,ted t l ~ ct o ~ i c r ? I ~ - i r ; t ~buildings ll~d src. rc13tiv~Iy111121f ? c t ~ . by d r:qt#irr.m~.nlsfor n;o?r.d or lrt.:~.tled loBundled lube. Slruclural s)slem in nhicn rira;hlr.l ~ e ~ l l rn u r t h sorilmnn ~ ~ u.all$ U -IIIIII~LIO.IT I ! ~ h ?:re i C U I I I O : ~ C ~ $!!to 18ngle \\:II1. IIICTC~! f~ri8ng cnmnr~zbll#!r . I n :t h,nJI;.I I.,h:. ~ndi\~J~:rl - - r~~ . ~ ~ tnf rtrc\\es 31 ihc inleridsc uf \a:h c o n l i n ~ ~ utuhc,. tube elemenlr may be ierminutcd a1 any nppropriste lcvcl ~~

-

2

Castellated beam. Bcvm fubricoted by culling Lhrough the web a f the hcsm with a profile burning machine, reporating (he two halves, moving one half along the other until the "tceth" o f the cu.tellationr and lack weldinr'the two hal$,cstoecthcr. Deeo "enelration Wcldinr is then ~ ~coincide. ~ urcd to wcld both sidcs o f the \s,eb.

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Center length. lar members.

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Distance along one member bctx,ecn intersections of ccnlcrlinrs o f perpendicu-

Central business district.

Key commcrciol iarso inridc most modem U.S. cilics.

Central-services core. Zone o f a high-rise building. often located cenlriilly in plan. where elcmtars. svairs, toilets, and ien.iccs shofts arc loc~lcd.Core may be cnclascd by co,lcrcle m r l l i or eiecl framer with lightwcighl cladding.

396

Glossary

Nomenclature In!,cned V i n appearance.

Chevron.

Code. Building code, o legal document providing design crilerin far buildings in a paniculvr jurisdiction. coefficient of variation. Rolio o f the rtvndard drvindon to the meno of n n n d o m variable. Concentrically braced frame. Frome i n which rcsislvnce l o lilteral load or frame instability ia provided by diagonal K o r other auxiliary system ofbncing. Core. Ponion o i n building lhvl includes elevaton, sloin, mrchvnical rhafl, and toilets, oflcn centmlly located.

Creep. Slow limc-depcndcnl change in dimcnrionr of concrete undcr il sustained loiid, primarily i n thc dirccdon i n whicl> !he load iicL5: u dimcnsionlesr qurntity having u n i u o f strain. Dirsiporion o f energy for dynamic lauding.

Damping.

Dapped girders. Girders (or bcbms) h w i n g u notch ul one or both ends in the underside to accommodate u corbel support within the girder depth or to crcrle additional rpnce for air ducts m d h e like.

Doubler.

Difiercnce or change between two vulucs.

Plate welded to or p i l r ~ l l eto l a web or nilngc to add strength.

Ductility.

Ahility o f il mnterb~lto ahsorb energy through defornlidtion without hilurc.

Eccentrically braced frame. Fiiamc i n which the ccntcriinc\ o f bracer air offset lrom !he paints ofintrrscctinn o f l h r crnturlinrs of bcami and columns. Environmental loads. Facade.

Lozids on a i t r u c u r r due to wind, mow, canhquakr, or tcnlpcraturc.

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Load combinations.

Loads likely to nct rimuiwneourly.

Load effects.

Momcntr, shcuis, and vxiul forcer i n u membcr dce l o loads or other actions.

Load factors.

Fuctors applied to o load to cxpresr probability of no1being excccded; safety factors.

Longitudinal.

Direction of the longer plan dimension.

M a x i m u m l o a d lultimate load). Plvsric limit load 'or rlability limit load. ur defincd: also manimum load-currying capocity of u rmcture under test.

Medium-rise building. mngc of 10 to ZO stories.

Shear wall following m i r r r g u l x line i n plan. (No1 u rectilinear asMultistory building ncithcr punicularly high nor low: usuillly i n the

Modulartubas. Condguoua framed tubular struaurnl aysremr which % togcthcr to form u complete bundlcd tube structure. M o m e n t resisting frame. lnlcgivted syslcm o f r m c t u m l elemcnu porrrrring cantinuily and hence capable o f resisting bending forcer. (Thcse fnmcr uruuily develop minor u i o l forcer.)

Puce, espcciillly thc piincipul elrvdtion. o f u building.

Factor o f safety.

Limit-state derign. Design process thal involver identification of all potential modes olfailure (limit rtnter) and mainlnining an nccepxable level of safety ogvinst their occurrence. Thc safely level is usually erlubiished on n probabilistic bnsir. .* , i o a d end resistance factor design. Design method i n which, a1 n chosen l i m i t swte, loo* effeels and resistances are sepnntcly multipiicd by factors ihal uccount for h c inherent uncenainlies i n the determinudon o f these quuntilier.

Meandering shear wall. semblage o f wnlli.)

L i l t r n l displaccmcnt due to laterill force.

Drift.

ir urunlly rcluted to there typcs of limit slntc), and (2) rrn~iceobilir). l i m i t slotcr, related to the criteria governing normal use of h e structure.

M e a n recurrence interval IMRII. A v c n g r time betu,rcn occurrences o f n random rvriablc thnt exceed its M R I value. The probability ihat h e MRI value w i l l be exceeded i n any occurrence is l/MRI.

A c ~ u i i weight l o f rlrucluml clumcna. (This is a gmrity lodd.1

Dead load. Differential.

397

Rulio o f ,Ire u l ~ i m a l rrrrrngxh (or yield point) a i 3 malcriol to ihc working

alrers i l i u m e d i n derign (stress foctor orrarcty): or ratio ofthc ultimntc loud, momcnl. or slrcvr o f a structur;,l mrmbcr to thc ss'orking loild. moment, or shcar, respectively, assumed in design (load fuccor o f rarely).

Mullion. Horizontill or vcnicul membcr of n window-wall orcunnin-wall system hrl is normally attached l o h e floor slab or benmr nnd ruppons thc glusr and/or elements o f a window widll. ..

Failure. Condition where o limit itute is reached. This mzy or may not i n ~ o i r ecollupsc ar other cvtvrtraphic occurrences.

Neoprene. Synthetic rubber boring physical prapenier closely resembling those o f n a r u n l rubbcr bur not requiring sulfur for vulcmizution. I t is made by polymerizing chloroprcncs. and the Intter is produced f i o m vcctylene and hydrogen chloride.

Fin.

Node.

Plate projecting from u member.

Flange m o m e n t connection. o f the column.

hlonlent connection in which the bcdm is connected to thc flange

Floor area ratio IFARI. Spccilicd ratio o f permissible floor space l o lot arc*. in which the inducemenl l o reduce lot coverage is sn impoiiant componml. Thc bidsic ratio is frequently inodilicd by providing "bonus" or "prcn~ium" floor npiacc for rucl, aspects as ilrcadcs. \rlb;icks. und plrziiq. Also called ldor mr;,~. Framed tube.

Pciimetcr ccluiwlent tube consisling o f closcly rpacrd columns ilnd rpiindrclr.

Fundamental period. i ' r r m . l i > i i l ~ ufir\t 111c,.lu8ll%#hr:ll#.ln .i.l tl~l8l.ln;. .Tlw 1111,: n ~ . ~ l d ~l.) s