Highlights of Recent Projects

8/2/2019 Highlights of Recent Projects

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H i g h l i g h t s o fR e c e n t P r o j e c t sF eatured in this section are brief design and constructiondescriptions of several recent projects using interestingapplications of precast and prestressed concrete. These projectsinclude a variety of buildings, bridges and special structures -ranging from a single-fam ily residence to long-span ove rpasses .The various exam ples show the versatil ity of precast/prestressedconcrete by which functional, esthetic and economical struc-tures can b e built.

*****Precast Prestressed Gymnasium Built to Resist Typhoons ......... 120Precast Panels Form 5 Million Gallon Water Tank .............. 122Architectural Precast Panels Clothe College Building ............ 125Precast Wall Panels Give Gymnasium "Classic" Look ............ 126Hollow-Core Slabs Form Attractive, Spacious Home ............ 127Prestressed Girders Blend Well With Bascule Bridge ............. 128Segmental AASHTO Standard Beams Increase Bridge Span ........ 130Precast Trapezoidal Girders Spl iced W ith Post-Tensioning

forHighway Underpass ............................. 132Prestressed I-Girders in Two Washington State Bridges ........... 134


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Precast Prestressed Gym nasiumPrecast concrete fin w al ls w ere used veryeffect ively to protect the m etal louv ers that funne lt rade w inds through a prestressed concretegymnasium in Guam from poss ib le dam age causedby typhoon s.


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Built to Resist TyphoonsThe combination of precast panels,precast prestressed slabs andpost-tensioned beams provided aneconomical solution for the NCS Gym-nasium in Gua m, the Mariana Is lands.

Because Guam is periodically subjectto typhoons (or hurricanes) with windvelocities up to or greater than 155 mph(250 km/hr), the 18,300 sq ft (1700 m2)gymnasium was designed with concretefin wall panels to protect the metal lou-vers which catch the trade winds to ven-tilate the building. During a typhoon, se-vere damage can result from flying ob-jects. The fins also create a pleasingpattern along the sides of the gym-nasium.

The upper, solid panels of the wallsare architectural precast concrete also,and the roof is constructed from precastpost-tensioned beams and precast pre-stressed roof slabs. A total of 163 pre-cast compo nents were used: 104 roof slabs, 4 in. x 8 ft (102mm x 2.4 m), lengths from 15 to 22

ft (4.5 to 6.7 m ). 5 post-tensioned beams, 12 in.(305 mm) thick x 86 ft (26.2 m), 5 ft(1.5 m) high at midspan, tapered to2 f t 8 in. (0.8 m) at the e nds for roofdrainage.

11 wall panels, 6 in. thick x 17 ftwide x 12 ft high (152 mm x 5.2mx3.7m).

43 window/fin wall panels, wedgeshape, 4 in. thick x 4 ft wide atwidest x 10 ft high (102 mm x 1.2mx3.0m).

A major factor which led to the choiceof precast concrete for the gymnasiumwas the 30-ft (9.1 m) height of the gym-nasium: precasting cut construction costand time. Other factors which made pre-cast concrete desirable were its resis-tance to corrosion and insect attack,both s ignificant problem s on the is land.

The exterior was finished with a ce-ment glaze coating for ease of mainte-nance. The gymnasium was completedin September, 1979.CreditsArchitect: Kenn eth Lee, Ken Lee AIA & A s-sociates, Tamuning, Guam.Structural Engineer: H. Hsia & Associates,Inc., Agana, Guam.General Contractor: Black Construction Cor-poration, Tumon, Guam.Ow ner: Department of the Navy. Adm inis-tered by Officer in Charge of C onstruction,Marianas, Pacific Division, Naval Fac ilitiesEngineering Comm and, FPO San F ran-

cisco, California.


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Precast Panels Form5 M illion Gallon W ater TankF orty precast prestressed concrete w al l pane ls,pos t-tensioned together, form a 5 m illion gal lon(19,000 m 3 ) water storage rese rvoir w ith aninterest ing architectural treatme nt of the exterior.

B ecause of the flat, open landscapearound Lubbock, Texas, this waterstorage reservoir was designed to be asattractive as possible from all directions.To do this, the vertically pretensionedwall panels were cast with vertical ribs;horizontal bands at about 5 ft (1.5 m)intervals interrupt the r ibs.

The 40 wall panels are 12 ft 4 in. wideby 35 ft 8 in. high (3.8 x 10.9 m). Theinside diameter is 158 ft (48.2 m), floorarea is 20,500 sq ft (1900 m2), and vol-

ume under the dome is 930,600 cu ft(26,355 m 3 ). The height to dome apex is53 ft 10 in. (16.4 m); wa ter level heigh t is24 ff6 in. (7.5 m).

The wall panels were pretensionedvertically by a combination of the "stackcast" method and the "boot strap" pre-tensioning bench. Using the stack castmethod, panel han dl ing equipmen t is notrequired at the site during the casting ofthe com plete project.

A pretensioning bench, 3 in. (76 mm)122


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thick and approximately 300 ft (91.4 m)long, was constructed at the site, withend abutments capable of resisting themoments produced by tensioning onelayer of strands only. After casting andovernight curing of the first layer, theend abutment stanchions were bracedagainst the first layer prior to tensioningthe strands of the secon d layer. A s imilarprocedure was followed for each suc-cessive layer of the stack cast; that is,bracing the end stanchions against the

last layer cast prior to stressing the nextlayer. This assured the overturning mo-ments and thrust of the strands of onelayer only were applied to the bench atany given t ime.The panels were removed from thepretensioning bench and e rected directlyin the tank by the use of a truck crane.After casting the vertical joints betweenpanels, the structure was horizontallyprestressed in bands by conventionalmethods. Finally, the horizontal pre-


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stressing bands were encased in con-crete producing the attractive horizontalcircular bands that contrast with the ver-t ical pretens ioned r ibs.

The vertical ribs provided the strengthto resist secondary moments created bythe concentration of the horizontal cir-cumferential prestressing and by differ-ential temperature and dryness effectsbetween the inside and outside faces ofthe wall. The rib effect was formed byboxes or cutouts placed in the castingbed. The thickness of the wall at the ribswas a constant 10 in. (0.83 m); wallpanel thickness ranged from 10 in. (0.83m) below grade to 4 in. (102 mm) at thetop of the wa ll.

The horizontal bands were a case of"form follows function." After erection ofthe wall panels by crane, the wall wasprestressed around the circumference.The high strength prestressing tendonswere applied at intervals around thewall. When they had been encased inhigh strength mortar, the result was the


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attractive architectural treatment of thetank exterior.In conclusion, the owner was able toachieve be auty for little, if any, additionalcost for the water tank and yet retainedthe engineering and performance ad-vantages of prestressed concrete con-struction. The structure has been in ser-vice, functioning very we ll, for over twoyears now and has become an attractive

landmark as one approaches the City ofLubbock.CreditsArchitect and General Contractor: Natgun

Corporation, Wakefield, Massachusetts(Francis X. C rowley, Project Architect).Engineer: Guy Wilson, City Engineer, Lub-

bock, Texas.Owner: City of Lubbock, Texas.

A r c h i t e c t u r a l P r e c a s t P a n e l sC l o t h e C o l l e g e B u i l d i n gAtotal of 121 architectural precast concrete pan els were used to clad the JackKassewitz classroom/office building for the M iami-Dade C omm unity C ollegeSouth Cam pus. The 28,000 sq ft (2600 m 2 ) building, which was c om pleted in 1979,uses 75 6-ft x 10-ft x 5-in. (1.83 x 3.05 x 0 .13 m) curtain wall panels and 46 9-ft x 8-ftx 5-in. (2.74 x 2.44 x 0.13 m) panels as solar shades. Exposed aggregate wasutilized effectively for both the cu rtain wall and solar shade panels.Architect/Engineer: Ferendino/Grafton/Spills/Candela, Coral Gables, Florida. (Hilario F.Can dela, Partner-in-Charge.)Co ntractor: Shafer & M iller, Inc., South Miam i, Florida.Architectural P recast C oncrete M anufacturer: L onestar Florida, Inc./Stresscon, Hialeah,

Florida.Owner: Miami-Dade Community College Board of Trustees, Miami, Florida.


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Precast Wall Panels GiveG ym nasium "C lassic" L ookLoadbearing architectural precast wall panels withstylized cornice openings give new recreationcenter an exterior which harmonizes with the classi-cal style of existing campus buildings.

The sports and activity center for theColorado Springs school used 8 x 22ft (2.4 x 6.7 m) precast architectural wall

panels effectively and economically toachieve an exterior treatment which is astylized version of existing campus ar-chitecture. The 12,200 sq ft (1135 m2)recreat ion ce nter also includes 24-in. (51mm ) double tees for the roof.

Cylindrical concrete columns andpilasters, precast wall panels withstylized cornice openings, fascia panels,and a c olor coat ing w ere used to visual lytie the new building to a neighboringbuilding, the "Petit Trianon," a cut stonebuilding with balustrades, pilasters, andcornices, modeled after the Trianon inFrance. Custom designed fiberglassforms were used to achieve the desiredrelief when casting the wall panels,

which are loadbearing except at theends of the gymnasium, where expan-sion may take place.

The prestressed double tees whichpermitted the necessary long free spansins ide the gym nasium w ere left exposed.The structure has been functioning withtotal satisfaction since 1978.CreditsOw ner: The Colorado Springs School, Co l-orado Springs, Colorado.Architects: Michael H. C ollins, Architect, Inc.,and John James Wal lace & Associates,Colorado Springs.Structural Engineer: Morgan & Associates,Colorado Springs.General C ontractor: Eller Con struction, Inc.,Colorado Springs.Precast C oncrete Ma nufacturer: Stresscon

Corporation, Colorado Springs.


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Hollow -C ore Slabs F ormAttractive, Spacious H om eA total of 90 precast concrete elements were usedby the architect who designed and built this housefor his ow n do m icile in En terprise, F lorida.

The structural strength of precast pre-stressed hollow-core slabs allowedthe architect/owner of this house to havea spacious interior, exterior decks andwalkways, and a roof strong enough foruse as a water collection basin for cis-tern recharge, with the capability of sup-porting solar collectors if desired.

The house, garage and storage areascomprise 4094 sq ft (380 m 2 ). A total of82 6-in. x 3-ft 4-in. (0.15 x 1.02 m)hollow-core slabs were used, withlengths of 13 ft 4 in., 18 ft or 22 ft (4.06,5.49, or 6.71 m). The remaining precastconcrete elements were 8 lintels, oflengths between 6 ft and 17 ft 4 in. (1.83and 5.28 m).

Perhaps the most striking aspect ofthis attractive house is the use of rec-tilinear components to achieve a non-rectilinear structure. The angles wereformed by cutting the prestressed slabsat 45-deg angles. Both pieces of the cut

slabs were u sed, providing op t imu m eff i-ciency of materials.The structure is fire resistant and im-pervious to insect attack. Urethanespray insulat ion is ap pl ied direct ly to roo f

slabs. The house was completed inSeptemb er, 1979.The architect/owner, familiar with the

inherent advantages of precast, pre-stressed concrete, has used it to createa top quality, maintenance free struc-ture.CreditsOw ner, Architect, and Gen eral Contractor:Gerald R. Gross, Gerald R . Gross & As-sociates, Enterprise, Flordia.Precast Concrete Manufacturer: HDWHoudaille, Orlando, Florida.Note: Another interesting building (a small office/shop) designed by the same architect and alsousing hollow-core construction was described in theMay-June 1979 PCI JOU RN AL, pp. 130-133.

PCI JOU R NAL/March-April 1980 127


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Prestressed G irders B lend WellWith B ascule B ridge

Th e use o f 70-in. (1.8 m) dee p preca st prestresse dconc rete girders provided an eco nom ical solut ionfor a bridge ove r a ship cana l in Wiscon sin with anove ral l length o f 1732 f t (528 m ).

The Sturgeon Bay Bridge, crossing aship canal, is a combination of pre-stressed girder spans with a concreteslab and a steel bascule unit with opengrid flooring. The overpass carries StateTrunk Highways 42 and 57 over thecanal at Sturgeon B ay, Wisconsin.

The greatest single advantage tousing prestressed concrete at this sitewas economic. It is estimated that asavings of at least 10 percent wasrealized by using concrete girders.

Since any material would requireerection from barges, concrete girdersoffered the s implest solut ion. They cou ldbe set directly on the piers and did notrequire the additional supporting equip-ment that would have been necessary ifspl ices were neede d.

Fabr ication of the beam s w as fas t andefficient, requiring a minimum amount ofconstruction time for the superstructure.The end result was a bridge that waseconomical to build and one that shouldprovide many years of minimum mainte-nance se rvice.

There are a total of 13 spans in thebridge. Of the ten prestressed girderspans, three are 114 ft (34.7 m) longand seven are 120 ft (36.6 m) long. Thebascule unit is 550 ft (168 m) long,which gives an overall bridge length of1732 ft (528 m). The bridge has a 34-ft(10.4 m) roadway and a 7-ft (2.1 m)pedestrian-bicycle area separated fromthe roadw ay by a concrete traffic barr ier .The overa ll width o f the bridge is 45 ft 11in. (14 m).


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Segmental AASHTOStandard Beams

Increase Bridge SpanPrecast segmental AASHTO Type IV Beams wereused very effectively with post-tensioning toincrease the span of an overpass in Florida.

P ecast segmental AASHTO Type IVBeams, post-tensioned together,formed a two-span continuous overpassat 127 ft (39 m) per span, comprising atotal length of 254 ft (77.5 m). Thebridge was located on Chipola NurseryRoad over 1-10 in Marianna, Florida.

Four segments per beam were used:two at 52 ft (16 m) and two at 72 ft (22m). Five lines of beams at 8 ft 3 in. (2.6m) centers were required. The beamheight is 4 ft 6 in. (1.4 m).

The following major features were in-corporated in the overpass.

AASHTO Type IV Beams wereused efficiently to increase the de-sign span by 30 percent for thissize girder.Unequal segments were utilized tomove temporary supports clear offast interstate traffic during con-struction.Shoulder piers were eliminated forsafer more graceful appearance.

The relatively lightweight segmentswere easily transported to the site bytruck set up in place on temporary sup-ports. The beams were then post-ten-


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Sixty prestressed girders, 70 in. (1.8m) deep, constitute the framing for theconcrete spa ns. The 70-in. I-girder ha s a2-ft 6-in. (0.76 m) top flange, 6-in. (152mm) web, and 2-ft 2-in. (0.66 m) bottomf lange.

The use of this special 70-in. (1.8 m)prestressed girder section provided theopportunity for prestressed concrete tobe an economical solution to the cross-ing of this ship canal. This girder sec-tion was developed several years ago toextend the use of prestressed concretebeyond the 100-ft (30.5 m) span rangein Wisconsin. The 70-in. (1.8 m) girderweighs the same amount per foot as theAASHTO 54-in. (1.4 m) girder and theallowable span length is increased from100 ft (30.5 m) with the 54-in. (1.4 m)girder to 130 ft (39.6 m) with the 70-in.girder.

This extra span length allowed the de-signer an econ om ical concrete structure.The girders were designed as continu-ous be am s for l ive load. This al low ed theelimination of one line of girdersthroughout the seven 120-ft (36.6 m)spans. An added savings was realizedthrough the use of low-relaxationstrands, which reduced by 15 percent

the total number of strands required ascompared to normal stress-relievedstrands.This bridge illustrates the way that twodifferent materials can be blended toprovide the most economical structure.The steel bascule span satisfies thenavigation requirements while the pre-stressed girder spans provide overalleconomy and a minimum maintenancebridge. The girder spans are com-plemented by the massive concretebascule p iers.The bridge was completed andopened to traffic in the spring of 1978and for the last coup le of years has be enope rat ing with total sat isfact ion.CreditsDesign Engineer: Bridge Section, Wisconsin

Division of Highways, Department ofTransportation, State of Wisconsin, Madi-son. (Chief Bridge Eng ineer: Will iam A.Kline).

General Contractor: Lunda ConstructionCompany, Black River Falls, Wisconsin.Precast Concrete Ma nufacturer: F. HurlbutCompany, Green Bay, Wisconsin. (Gen-eral Manager: Vishnu Joshi).Own er: State of Wisconsin.

PCI JOU RN AL/March-April 1980 129


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s ioned i n to a two-span con t i nuous strands, was stressed with a 500-tonstructure after concrete in the slab and ram. Two tendons were required foropenings between segments had been each beam. The jacking force on eachplaced and properly cured. The seg- tendon was 960 kips. The overpass wasments were prestressed only for the completed in July 1979.dead load of beam and slab in the pre-stressing yard.oncompletion of the segment place- Engineer-Owner: Florida Department ofTransportation, Design -Structures, Tal-ment and the slab having been cast, lahassee, Florida ,the w e r e and Contractor: Morris-Shea Construction Com-threaded through the entire length of pany, Birmingham, A,abama.bridge. Anchor plates were set and the Precast Concrete Manufacturer: Southerntendons stressed. Each tendon, com- Prestressed Concrete, Inc., Tallahassee,prised of thirty %-in. (13 mm) diameter Florida.

PC1 JOURNAU March-April 1980 131


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RD.t--

PRECAST. TRAPEZOIGIRDERS; POST-TENSIONED/ 4 7.. $I 4WITH CAST- IN -PLACEDECK Ia Qtendons were cast in to the g irders with T h e u s e o f p re c a s t se gm e nt sthe proper profile. minimized the nee d for falsework and

At the bridge site, the segments were enabled cons truction to proceed with aerected on temporary bents (see dia- minim um disruption of traffic, without re-gram) and the post-tensioning tendons quiring additional clearance height forwere pulled through the ducts. Post-ten- falsework. Construction time was alsosioning anchorages and end block rein- reduced. The bridge has been in serviceforcement were located in the cast-in- for just over a year.place end diaphragms. Because of thesingle column pier at the bridge mid- creditspoint, the so lid portion over the pier wasalso post-tensioned transversely (see Owner and Engineer: Structural Office, On-diagram). tario Ministry of Transportation and Com-m u n i c a t i o n s , D o w n s v i e w , O n t a r i o ,After placing concrete in the deckslabs, and the solid portion General Contractor: Armbro Materials & Con-over the pier, the post-tensioning ten- struction ~ t d . , rampton, Ontario.dons were stressed and grouted and the Prestressed Concrete Manufacturer: Preconbridge completed. Ltd., Brampton, Ontario.


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Closeup of West Prosser Interchange. Washington State 100 series prestressedI-girders were used.

Prestressed I-Girders inTwo Washington State Bridges

Two-span highway br idge (West Prosser Interchange). Note that exposedaggregate wing walls were designed to blend with environment.


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Closeup of C helan River Bridge show ing ex po sed aggregate abutment.

These two Washington State bridges (one locatedin the countryside and the other in an urban setting)illustrate the versatility of standard precastprestressed I-girders.

Smmet ry o f des ign a l l owed twoWashington State bridges to bebuilt using standard precas t, prestressedconcrete I-girders, helping to hold downdesign time and construction costs. Theminimal use of falsework was also anadvantage in both cases. Each bridgecontains seven I-girders per span.a The two-span bridge at a highwayinterchange near Prosser, Washington,

used the Washington State 100 seriesgirders, cast at 101 ft 1 1 in. (31.3m).Continuity at the intermediate pier in-creased the ultimate load capacity of thegirders. Wing walls at each end shortenthe span lengths. The total bridge lengthis 210 t (64m).

The "f rame" arou nd the expose daggregate finish in the w ing walls givesan appearance of supports with endcantilevers. Exposed aggrega te finish inthe wing wall panels was chosen to tiethe bridge to its surroundings. The dou-ble column support in the roadway me-dian recedes within the shadow of thesuperstructure, so the clean horizontallines of the girders stand out.

a The four -span br idge over theChelan River, 540 t (165m) long, used135 ft (41 I m) Washington State 120Series I-girders. Because of the depth ofthe water at the bridge site, buildingwithout falsework meant considerableeconomy. This bridge also uses an ex-


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Highlights of Recent Projects

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