Built in 1902, the Ingalls Building in Cincinnati was the first re i n-f o rced concrete skyscraper in America. Standing 210 feet high, the

1 6 - s t o ry building is still in use today. Not until after World War II,h owe ve r, did concrete buildings exceed 20 stori e s. Higher buildingswe re uneconomic because then-current codes re q u i red larg ecolumns that took up too much rentable floor space. Not until them i d - 1 9 5 0 s, when elastic design was replaced by ultimate strength de-sign, did concrete building heights begin to ri s e. In 1959, Chicago’sEx e c u t i ve House Hotel became the United St a t e s’ highest re i n f o rc e dc o n c rete building at 371 feet. The previous re c o rd holder had beenbuilt in the twenties.

Ultimate strength design permitted savings in the volume of con-c rete and the amount of re i n f o rcement needed and in form w o rk costs.

The world’s tallest concrete buildings—today and yesterday

PAST TITLEHOLDERSAMONG THE WORLD’S TALLEST

Each of the buildings listed here was, at thetime of its completion, the United St a t e s’tallest re i n f o rced concrete building. In somecases (designated by asterisk) the buildingheld both U.S. and world re c o rd s...for exam-p l e, Water Tower Place which still retains its“w o r l d’s tallest” title.

Readers with documentation on other tallbuildings are invited to share their know l e d g e.We have found no single authori t a t i ve listingof these re c o rd-making stru c t u re s...so we’rew o rking to create one.

Year He i g h tBu i l t ( Fe e t )

1902 Ingalls Bu i l d i n g 2 1 0Cincinnati, Oh i o

1 9 2 2 Medical Arts 2 3 0Bu i l d i n gDa l l a s, Te x a s

1 9 5 9 Ex e c u t i ve Ho u s e 3 7 1Ho t e lC h i c a g o, Il l i n o i s

1 9 6 0 Bank of Ge o rg i a 3 9 1Bu i l d i n gAtlanta, Ge o rg i a

1 9 6 2 Ma rina City 5 8 8 *C h i c a g o, Il l i n o i s

1 9 6 5 1000 Lake Sh o re 6 4 0 *Plaza Ap a rt m e n t sC h i c a g o, Il l i n o i s

1 9 6 7 Lake Point Towe r 6 4 5 *C h i c a g o, Il l i n o i s

1 9 6 9 One Shell Pl a z a 7 1 4 *Houston, Te x a s

1 9 7 5 Water Tower Pl a c e 8 5 9 *C h i c a g o, Il l i n o i s

HOW DO YOU TELL HOW TALL A BUILDING IS?

It would seem more than a little difficult with a tape measure. But even ifit we re not, where would you start measuri n g — f rom the basement slab,f rom street level, from the front entrance or the back? And how far wouldyou measure? What is the top of the building—the roof line, the top of the el-e vator shaft or the tip of the antenna? And once you have figured all that out,what keeps the building from shrinking under all its weight? Obv i o u s l y, itwould be much simpler, in the record-keeping business at least, if all con-tenders we re built on the same street. The tallest building, then, would bea p p a rent, without dispute.

Even without this luxury, though, the question is easily sidestepped. Theheight of a building is not measured; it is calculated. Building heights are de-sign heights. Water Tower Place may not be exactly 859 feet 2 inches, buta c c o rding to the bluepri n t s, it should be. By all re p o rt s, no one forgot tobuild a floor. And, at the most, it could have been shortened only a foot byc re e p.

If more than one height is re p o rted for a building, it is probably becauseone was taken from the antenna and one from the roofline or one from thef ront entrance and one from the back or possibly, of course, because one issimply wrong. A good figure to use is the design height from the sidewalk atthe main entrance to the ro o f l i n e.

But even design heights can change as construction pro g resses and de-signs are altered. In construction of the CN Tower in To ro n t o, for example(see story, page 125), a 335-foot-high steel plate antenna was substitutedfor a 325-foot-high steel tube antenna, because the steel for the shorter de-sign could not be delive red soon enough. The final design height of 1815 feetwas consequently 10 feet higher than the original design height.

With the material savings and the added floor space thatultimate strength design provided, concrete high-ri s ec o n s t ruction escalated—litera l l y. In 1960, the Bank ofGe o rgia Building surpassed the Ex e c u t i ve House Ho t e l .Two years later the Bank of Ge o rgia Building was sur-passed by Ma rina City Towe r s, and in 1964, Ma rina Tow-ers was out-topped by Mo n t re a l’s Place Vi c t o ri a .

Soon, the improvements in concrete stru c t u ral designwe re matched by improvements in the material itself.Hi g h - s t rength concrete with strengths up to 10,000 psiwas developed to keep columns small while buildingsg rew higher and higher. Lightweight concrete and eve n-tually high-strength lightweight concrete reduced build-ing dead loads. In rapid succession the world’s tallest re-i n f o rced buildings we re surpassed by even tallerc o n c rete buildings. Place Vi c t o ria was surpassed byC h i c a g o’s Lake Sh o re Plaza Ap a rtments; 1000 Lake Sh o rePlaza was surpassed by Lake Point Towe r.

To d a y, the world’s tallest re i n f o rced concrete buildingis Chicago’s Water Tower Pl a c e. The second tallest, builtafter Water Tower Pl a c e, is the MLC Ce n t re in Syd n e y,Au s t ralia. Others among the tallest are the Pe a c h t re eCenter Plaza Hotel in Atlanta, and in De t roit the Re n a i s-sance Center Westin Hotel. These buildings stand ascolossal monuments to the perf o rmance of concre t e — am a t e rial that continually (though not surprisingly) out-p e rf o rms itself, and now h e re more so than in high-ri s ec o n s t ru c t i o n .

Rising 859 feet 2 inches above street level, Water Tow-er Place is the world’s tallest re i n f o rced concrete build-ing. Oc c u pying an entire city block on Chicago’s No rt hMichigan Ave n u e, the mixed-use building consists of a7 4 - s t o ry tower and a 12-story base. The base houses atheater hall, a 7-story shopping center with atrium and 2s t o ries of office and commercial space. Ab ove the 12ths t o ry the tower contains a luxury hotel and condomini-um re s i d e n c e s.

Structural design

St ru c t u ra l l y, the tower is a multicell tube, 94x221 feet.Bisecting its long side, a shear wall extends from tra n s-fer girders at the 13th floor level upw a rd to the 74th floor.This shear wall, va rying from 18 inches thick at its baseto 8 inches at the top, takes 65 percent of the wind loads.The exterior columns take 30 percent, and the interi o rcolumns take 5. The 10-foot-deep transfer girders at the13th floor transfer loads from above to the columns andtwo cores that extend down to the foundation caissons.

Though steel was originally considered for the build-

i n g’s stru c t u ral design, concrete was selected becausethe hotel and condominiums did not re q u i re long spansand because high-strength concrete provided a re d u c-tion in both the size and number of concrete columnsn e c e s s a ry. Mo re ove r, since slabs could be finished on theu n d e r s i d e, drop ceilings we re not needed as they wouldh a ve been in a steel-framed stru c t u re. Omitting dro pceilings reduced the building height by 80 feet.

Concrete quality

Co n c rete of seven different strengths from 3000 to9000 psi was used in construction of Water Tower Pl a c e.Ge n e ra l l y, the columns in the 12-story portion of thebuilding we re formed with 6000-psi concre t e. In the tow-e r, from the foundation to the 25th floor, columns we remade of 9000-psi concre t e. Ab ove the 25th floor, columnc o n c rete strength was decreased pro g re s s i vely fro m7500 psi to 4000 psi.

Water Tower Place—859 feet Chicago’s Water Tower Place, the world’s tallest reinforced

concrete building, is literally a city within a city. The 859-foot-high building contains condominium residences,offices, a shopping center and a luxury hotel.

To produce the high-strength concre t e, water re d u c-ing and re t a rding admixtures (ASTM C 494, Types A andD) we re used. Also, all mixes except the slab concre t econtained 100 pounds of fly ash per cubic yard. The ad-dition of fly ash increased strength more than mix de-signers thought additional cement could. Air- e n t ra i n-ing admixtures we re not used in the high-stre n g t hc o n c re t e.

Floor slabs we re placed with 4000-psi stru c t u ral light-weight concrete weighing 105 pounds per cubic foot. Inthe 12-story low - ri s e, 10 _-inch-thick two-way slabs with4 _-inch drop panels we re used, while 7 _-inch flat plateslabs we re used in the high-ri s e. By using lightwe i g h tc o n c rete instead of a more conventional 145-poundc o n c rete mix, slab dead loads we re reduced by morethan a third .

Without this lightweight concre t e, Water Tower Pl a c ef o u n d a t i o n s, like those of the John Hancock Bu i l d i n g ,its next-door neighbor to the north, would have had togo 120 feet to reach bedrock—plus another 5 or 6 feet in-to the rock. Instead, the high-rise is founded on 153 cais-sons that go down only about 80 feet to hardpan. Thel a rgest, located under the tower core, are 27 feet in di-ameter with 10-foot shafts; each re q u i red 250 cubicy a rds of concrete to form and each has a design work i n gload of 14,600 kips.

Completed in 1976 at a cost near $195 million, Wa t e rTower Place contains about 160,000 cubic yards of con-c rete and nearly 12,000 tons of re i n f o rcing steel.

Credits (all Chicago firms)Architects-Engineers: Loebl, Schlossman, Bennett and Dartand C. F. Murphy AssociatesGeneral contractor: Inland Robbins Construction CompanyConcrete contractor: James McHughReady mixed concrete: Material ServiceOwner: Marban, a joint venture of Urban Investment andDevelopment Company, subsidiary of Aetna Life and Casu-alty Company, and Mafco Incorporated, subsidiary of Mar-shall Field & Company

An urban social center, the MLC Ce n t re in Syd n e y,Au s t ralia includes a 68-story towe r, a 1000-seat re s t a u-rant, an 1100-seat theater, retail space and underg ro u n dp a rking. Rising 808 feet high, the $110 million, 68-storyc o n c rete monument is Au s t ra l i a’s tallest re i n f o rced con-c rete building and also the world’s second tallest.

Octagonal in plan, the building has a tube-in-tubes t ru c t u ral design. Instead of closely spaced columns,though, it has only eight columns, one at each point of

the octagon. Ma s s i ve, 6-foot-deep spandrel beams spanb e t ween columns. Designed with an I-shape cro s s - s e c-tion to shade the windows from the sun, these spandre l sa l t e rnately span 35 and 60 feet around the peri m e t e r.Both columns and spandrels we re cast in place usingp recast concrete panels as form w o rk. The stay- i n - p l a c ef o rms provided a high quality exterior finish and allowe dthe unusual spandrel shapes to be easily constru c t e d .

Innovative construction methods

Re u s a b l e, pre f a b ricated steel trusses we re used to sup-p o rt the spandrels of the top three floors under con-s t ruction. These trusses carried the dead load of thes p a n d rels directly to the columns until the spandrel con-c rete developed the necessary strength. A series of ve rt i-cal trusses braced the top three floors against wind, anda hori zontal truss at the top was used as a working plat-f o rm. The entire shoring unit was raised from floor tofloor by cra n e.

MLC Centre—808 feet

At 808 feet, the 68-story MLC Centre in Sydney, Australia isthe world’s second tallest reinforced concrete building. Inconstruction of the octagonal tube-in-tube structure, anuncommon forming system reduced the amount of shoringand eliminated reshoring.

A two-part, climbing box form was used to cast thebuilding core. Once the core had been cast for one floorl e vel, the inside box form was re t racted, raised to thenext floor level and attached to supports provided in thel ower lift of concre t e. Then the outside form was re t ra c t-ed, raised and fastened to the inside form with wall ties.Co n c rete was placed, and the cycle was re p e a t e d .

Beam and slab floor construction

In constructing the floors, regular steel re i n f o rc e m e n tfor the beams was replaced with pre f a b ricated, open-web box tru s s e s, which permitted the amount of shori n gto be reduced. The trusses carried part of the dead loadof forms and uncured concrete to the columns. As thec o n c rete developed strength, the function of the tru s s e sp ro g re s s i vely changed from supporting the concrete tore i n f o rcing it. Steel trusses we re used in the pri m a ryfloor beams that spanned from the columns to thebuilding core, and smaller trusses we re used in the sec-o n d a ry beams that spanned between the pri m a ryb e a m s. The remaining dead load was carried by shori n gp o s t s. Fo rm w o rk was designed to strip around thes h o res without disturbing them. Re s h o ring was thuse l i m i n a t e d .

Compared to a 6- to 10-day cycle estimated forconventional methods, this forming system en-abled a floor to be completed every 4 days, de-spite wind, wet weather and labor troubles. Inthe typical cycle, service core construction rantwo levels ahead of perimeter constructionwhich in turn ran one and a half levels ahead offloor construction.

Co n c rete placementNo obstruction to city traffic was permitted, so all ma-

t e rials had to be unloaded within site boundari e s. Co n-c rete on the project was placed by hoist and conve yor orhoist and wheelbarrow. Two hoists we re positioned inthe elevator shaft to lift concrete from Level 3 to the lev-els under construction. St reet level was at Level 7. Co n-c rete trucks entered the basement parking garage en-t ra n c e, drove down ramps to Level 4 and discharg e dtheir loads into two 8-cubic-yard holding hoppers. Fro mthe holding hoppers, the concrete was tra n s f e r red byc o n ve yor to the concrete hoists and by the hoists to thec o n s t ruction level. At the top of the hoist, concrete wasd i s t ributed hori zontally by conve yor to the core walls,columns and spandre l s. Floor slabs we re placed usingw h e e l b a r row s.

CreditsArchitect: Harry Seidler and Associates, Sydney, N.S.W.Structural engineer and general contractor: Civil & Civic Pty.Ltd. Developer: Lend Lease Corporation, Sydney, N.S.W.Owner: Mutual Life and Citizens Assurance Co. Ltd., Syd-ney, N.S.W.

Peachtree CenterPlaza Hotel-723 feet

When completed in late 1975, only months after Wa t e rTower Place was topped out in Chicago, At l a n t a’sPe a c h t ree Center Plaza Hotel was the world’s secondtallest re i n f o rced concrete building and the world’stallest hotel.

Designed by arc h i t e c t - d e veloper John Po rtman, thec y l i n d rical, glass-walled building incorporates a much-copied and much-celebrated design feature that Po rt-man first used in 1967 when he designed the Hyatt Re-gency Hotel in Atlanta—the open atri u m - l o b by. InPe a c h t re e, howe ve r, the hotel is not built around the atri-um; it is built over the atrium, supported only by tencolumns and the building core.

A round this 7-story atri u m - l o b by, the floors of the 9-s t o ry, rectangular base are stepped back in tiers, eachfloor overlooking the one below. The cylindrical hotelt ower splits this rectangular base into two sections: aback section that contains meeting rooms and officesand a larg e r, front section that contains the ballroom, ex-hibit space, meeting ro o m s, shops and an indoor swim-ming pool. The two sections are connected by walkwaysthat span the atrium and wrap around the core.

Na t u ral light enters the atrium by skylights that encir-cle the cylindrical hotel towe r. At the top of the 116-foot-diameter cylinder is a thre e - l e vel re s t a u ra n t - c o c k t a i llounge serviced by two glass elevators that run up andd own the outside of the towe r. In Po rtman fashion, theupper cocktail floor and the lower dining level re vo l ve,p roviding the highest, most panoramic view of At l a n t a .Now the world’s second tallest hotel, Pe a c h t ree houses1100 hotel rooms and cost $55 million to build.

Structural system

The hotel’s ten support columns rise 88 feet out of ah a l f - a c re lake that covers most of the lobby floor exc e p tfor the check-in area and cocktail “islands.” These sup-p o rt columns are each 7.6 feet in diameter, all re i n f o rc e dc o n c rete with a textured paint finish. Each contains5000-psi concrete and eighty 1.4-inch-diameter re i n-f o rcing bars, and each supports 10 million pounds.

At the top of the atri u m - l o b by, these columns give wayto shear walls that extend to the top of the hotel towe r.This transition from columns to shear walls is made pos-sible by 11-foot-deep, box elements that are as wide attheir middle as the columns and as long as the shearw a l l s. This 11-foot-high transfer level is used for me-chanical equipment.

The shear walls radiate out from the 53-foot-wide

building core like spokes of a wheel. Two hotel rooms arelocated between each pair of walls. Up to the 24th floorl e vel, both shear and core walls we re built with 5000-psic o n c re t e. The core walls range from 14 to 8 inches thickand the shear walls from 21 to 10 inches thick. The build-ing core carries 64 million pounds. Be l ow the hotel-room cylinder, all lateral loads are tra n s f e r red to the coreand by the core to the foundation mat, the atri u mcolumns take none.

Floors are flat plate concrete slabs, all stru c t u rally tiedto the core walls for an extra-stiff stru c t u re. Pie-shapeflying forms we re used to cast the floor slabs, and metalgang forms we re used for the core walls and columns.

Using an all-concrete stru c t u ral design, as opposed toa tubular design with steel perimeter columns and ac o n c rete core, reduced the height Pe a c h t ree might haveneeded by 60 to 70 feet. And, by using concre t e, con-s t ruction was able to start sooner—and thus finish soon-e r.

CreditsArchitect-engineer: John Portman & Associates, AtlantaGeneral contractor: J. A. Jones Construction Company,Charlotte, North CarolinaDeveloper: Portman Properties, Atlanta

RenaissanceCenter WestinHotel—720 or740 feet?

Depending on what side of the building you are stand-ing on, De t ro i t’s Westin Hotel is today the tallest hotel inthe world—or the second tallest. Built on a slopingg ra d e, the 70-story towe r, to the best of our inform a t i o n ,stands 720 feet above the main entrance and 740 feeta b ove the back entra n c e. Both entrances are street leve l .If you live in De t roit, you are likely to measure the build-i n g’s height from the back entra n c e, making Westin thew o r l d’s tallest hotel and the world’s third tallest re i n-f o rced concrete building. Howe ve r, if you live in At l a n t a ,w h e re the Pe a c h t ree Center Plaza Hotel rises 723 feet onall sides, you are more likely to measure the height ofWestin Hotel from its main entra n c e, making Pe a c h t re e,not Westin, the world’s tallest hotel and third tallest re i n-f o rced concrete building. If you live neither in De t roit orAtlanta, you will probably concede that standing on thesidewalk in front of the Westin Hotel, you cannot re a l l ytell whether it is 720 feet tall or 740 feet tall. The fact is,

Pe a c h t ree and Westin are the world’s tallest hotels—butonly for now.

Design similar to Peachtree

The centerpiece of De t ro i t’s $750-million Re n a i s s a n c eCe n t e r, Westin Hotel is surrounded by four octagonal of-fice buildings each 39 stories high. All five buildings ri s ef rom a 750x800-foot cast-in-place concrete podium thatcontains store s, ballro o m s, meeting ro o m s, re s t a u ra n t s

Strong similarities existbetween Peachtree PlazaHotel in Atlanta and theWestin Hotel in Detroit. Bothare John Portman designs.The Atlanta hotel (shownduring construction at left) is723 feet high. The Detroitstructure, largely hidden bythe office towers of theRenaissance Center above, is720 feet or 740 feet,depending on the referencepoint selected formeasurement. Both rankamong the world’s tallesthotel buildings.

and parking space. Fu t u re plans include ten additionaloffice buildings and a row of apartment buildingsf ronting directly on the De t roit Rive r.

Designed by architect John Po rtman and built in 1977,the cylindrical hotel is a close replica of his Pe a c h t re ePlaza Hotel built only two years earlier. Like thePe a c h t re e, Westin Hotel is a re i n f o rced concrete cylinderbuilt over a 7-story atri u m - l o b by and enclosed byb ro n ze-tinted re f l e c t i ve glass. A thre e - l e vel re s t a u ra n tatop the hotel is serviced by two glass elevators that ru nup and down a 22-foot-diameter tower on the outside ofthe hotel. El e vator service to other floors is provided byan 18-car elevator shaft at the hotel core.

We s t i n’s stru c t u ral design is also similar to thePe a c h t re e’s. Twe l ve cast-in-place concrete columns,each 71⁄2 feet in diameter, are arranged in a 109-foot-di-ameter circle concentric with the 128-foot-diameter ho-tel towe r. Each column extends 102 feet from its sup-p o rting caisson through the service level and thel o b by- a t rium to transition members between the sev-enth and eighth floor leve l s. In the hotel-room floorsa b ove radial bearing walls taper from 2 feet thick at theiroutside to 1 foot thick at their inside. Rooms are locatedb e t ween these radial walls, and the seventh floor tra n s i-tion level is used for mechanical equipment.

Meeting room areas

A 2-story meeting room ring encircles the hotel at thebottom. While the hotel tower has a 64-foot ra d i u s, thering has an outside radius of 122 feet and an inside ra-dius of 871⁄2 feet. The 23-foot space between the exteri o r

of the hotel and the inside wall of the meeting room wingis cove red by skylight. The ring is built of cast-in-placere i n f o rced concre t e. It is founded on 24 py l o n s, each2x10 feet in cross section, with the 10-foot sides posi-tioned ra d i a l l y.

Pumped concrete

Co n c rete on the project was pumped, but since thepump was located no more than 16 floors below the top-most level being cast, the pump was in turn supplied bya hoist and bucket. Floors we re cast using pie-shapef o rms that we re flown from floor to floor by two towe rc ra n e s, each with a 110-foot boom and a maximum lift-ing capacity of 15,500 pounds. Sl i p f o rming the outsidee l e vator tower freed these two rooftop cranes for workon the building towe r.

CreditsArchitect-Engineer: John Portman & Associates, Atlanta,GeorgiaConstruction Manager: Tishman Construction Company,New York, New YorkConcrete Contractor: Mayfair Construction Company,Chicago, IllinoisOwner: Renaissance Center Partnership

PUBLICATION #C830091Co py right © 1983, The Ab e rdeen Gro u pAll rights re s e rve d