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  • View Publication

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  • THE HIGH-SPEEDBUILDING OPTION

  • (!zKaxlGREUETHE HIGH-SPEEDBUILDING OPTION

    CONTENTSTime is money

    Meeting end-user needs

    Choice of framing systems

    Concrete-the bestinvestment

    The future

    Front cover, from top

    Snow Hill Redevelopment,

    Birmingham

    Client: Sun Alliance GroupPrecast frame, 12 storey,I-day floor cycle

    South Quay Plaza, Isle of Dogs,LondonClient: Marples International

    In situ frame, Phase 3,5-day floor cycle

    Cascades, Isle of Dogs, LondonClient: Kentish Homes

    In situ frame, 20 storey,5day floor cycle

    This publication has been commissioned by theReinforced Concrete Council.

  • TIME IS MONEY

    Chelsea Harbour Development, LondonClient: P & O DevelopmentsIn situ frame, tower block,3-day floor cycle

    Time is Money-the faster a buildinggoes up and is occupied, the sooner thereturn on investment, and the lower thefinancing costs.

    From contract award to completion, nobuilding system moves faster than areinforced concrete frame-whether itis precast, in situ or a combination ofboth.

    City Harbour Development, Isle ofDogs, LondonClient: British Land, Summit Group,MBO Joint VenturePrecast frame, 8 storey,7-day floor cycle

    Broadgate Phases 9 & 10, LondonClient: Rosehaugh Stanhope Developmentsand British Rail Joint VentureComposite frame, 8 storey,4000 m2 per week

  • MEETING END-USER NEEDSMost companies and organisationsnow recognise the need to use space tomaximum advantage and to ensure thatboth current and projected officerequirements are fully satisfied.

    For new off ice construction, thedeveloper and the professionaladvisors need to take account of suchrequirements and assess the quality,cost and time considerations fordifferent types of construction.

    The demand for versatility in officespace has never been greater.

    The need for longer spans to providefloor space uninterrupted by coresand columns.

    Provision of maximum floor-to-floorheight to allow zones for servicesand ducts, balanced against greaterplanning pressure to limit overallbuilding height.

    A more adaptable structure, so thatfuture tenant alterations can beactioned with maximum speed andminimum disruption.

    Ribbed construction for flexibility to accommodatetenant alterations

    The wide range of adaptable floor con-struction in reinforced concrete andthe scope for spatial planning, makesconcrete the right choice -offeringa positive solution to meet end-userneeds, both now and in the future.

    Digital controls for environmental systems

    Shearheadsfor service openings close to columns

    Raised floors for cable ducting

    Flat soffits for freedom to route services

  • CHOICE OF FRAMING SYSTEMSFor most building types there is aconcrete framing system that fits.Concrete construction can be in situ,precast or composite (a combination ofprecast and in situ) with a further choiceof prestressed or reinforced, normalweight or lightweight concrete. In otherwords, concrete offers the widest rangeof framing options to choose from.

    Each option provides benefits in timeand cost to suit particular siterequirements, building size, storeyheight, and end-user needs. From atotally in situ process (with its shortlead times, and competitive prices) to awholly precast building (made to closetolerance under factory conditions),there is a concrete framing system thatis tailored to the projectrequirements.

    TYPICAL APPLICATIONSSOLID FLAT SLABThe benefit of a solid flat slab is its flushsoffit. which makes construction easy.Minimum depth of construction allowsgreater flexibility for routing horizontalservices.

    RIBBED SLABIncreases the economical span rangeof flat slabs, by reducing self-weight.A very adaptable structure foraccommodating openings in floors.Spans: 8 to 14m.

    BAND BEAM AND SLABThe band beam has a relatively wide,shallow, cross-section, which reducesthe overall depth of floor whilstpermitting longer spans.Spans: 8 to 15 m.

    W A F F L E S L A BCommonly used in buildings subject toheavy loadings. A very material-efficient design, but the extra formworkcan slow construction speed.Spans: 8 to 18 m.

    DOUBLE T PRECAST BEAMSPrecast beams of standard profile arerelatively light units of high loadcapacity capable of long spans.Spans: 8 to 20 m.

    Typ. 8.0 mv

    PRECAST AND COMPOSITEFLOORSPrecast and composite floors offerthe advantages of manufactureunder factory conditions, eliminatingsite formwork and reducing sitelabour. The option of prestressingprovides additional benefits of longspan and high load capacity.Spans: 6 to 11 m.

    h Typ.2.4m

    Composite floor

    w

    Span L(m)

    For typical office loading

    /Typ. 8.0 m/ Typical economical spans

  • CONCRETE - THE BEST INVESTMENTLead-in time, construction time,financial outlay and cash flow are realcost variables-just as real as the costof cement, stone and steel. A reinforcedconcrete structure offers the buyer themost attractive long-term investmentopportunity for major city projectsbecause it:

    n lowers the initial costn minimises life cycle ownership costn reduces construction time and

    material cost

    LEAD-IN TIMEConcrete, reinforcement and skilledlabour are all locally available-soconstruction begins with a minimumwaiting period for fabrication ofmaterials. A cast-in-place structure canoften be well under way before thebuilding plans have been finalized.

    024 8 16 22 26

    Weeks from notice to proceed

    Lead-in time

    CONSTRUCTlON INVESTMENTCOSTSConcrete building materials aredelivered to meet constructionschedules. This spreads the cashoutlay for materials into smallerincrements over a known time frame.The shorter overall schedule and on-time record of concrete offer majorinterest and income advantages to thedeveloper.

    EXTERIOR CLADDING,MECHANICAL AND ELECTRICALCOSTSThe storey height of a concrete buildingcan be less per floor than a steel-framedbuilding-by as much as 300 mm. Thisminimizes the exterior surface area tobe enclosed, as well as the vertical runsof mechanical and electrical systems.

    HVAC COSTHigh mass makes concrete a significantthermal reservoir, which helps toreduce peak demand on HVACequipment. This, combined with thereduced volume of concrete buildings,could lead to cheaper serviceinstallations, and lower running costs.

    Up to 3.0 m higher

    ;/,

    , /1~

    , /7 -/, //I-

    1_

    ConcreteIj Sde/ II

    10-storey building

    Building volume

    FIRE PROOFINGConcrete needs no additional appliedfire proofing to comply with buildingcodes and regulations. This lowers riskfor both building and occupant and mayqualify concrete structures for reducedinsurance premiums.

    PREFABRICATIONOff-site prefabrication, i.e. columns,floors, and reinforcement, reduces sitestorage facilities, requires lower levelsof site labour and is less sensitive toweather conditions.

    Precast frame elements

    I Heat gainBtuh/ft2

    0 2 4 6 8 10 12 14 16 18 20 22 24

    Hours

    - 6 Concrete U 0 12Metal deck U 0 12

    (Portland Cement Association USA)

    Thermal reservoir comparison

    MARKETABLE SPACEHigher strength concrete and improveddesign technologies allow longer spanswith fewer, smaller, columns. Offeringmore usable space, concrete buildingsare highly marketable to commercialtenants.

    fcu=70N/mm2

    I fcu=40N/mm2

    Comparison of column sizes

    Cash-flow comparison

  • CASE STUDIES No.1I

    British Cement Association has BCA proposals for speedTheundertaken a number of case studieson specific major city projects, todevelop alternative proposals forrapid construction in reinforcedconcrete. All these proposals havebeen appraised and assessed byconstruction specialists and thefindings accepted by the clientsconcerned.

    Here are just two examples:

    FRAME TIME

    Flat slab construction 15 weeks

    Post-tensioned flat slab 15 weeks

    Precast construction 13 weeks

    Lift slab construction 18 weeksDOCKLANDS-TYPE

    c 36.6 m 4TYPICAL FLOOR PLAN

    OFFICE BLOCKA six-storey office/residentialdevelopment with a total floor area of11,000 m2. Architectural featuresinclude an internal coveredcourtyard and external facade clad ingranite panels, four main lift andstairway cores, with three additionalsecondary escape stairways.

    ConclusionKeeping to the original brief, butredesigning the frame to encouragefast construction, several weekscould have been saved on theoriginal programme.

    EAST ELEVATION

    Original scheme Programme Cost (/m2)Steel frame with18 m lattice beamcompositemetal/in situconcrete deck,and fire spray 18 weeks 130

    BCA proposalsPost-tensionedbeam and slab,using light-weightconcrete 18 weeks 110

    Precast concrete18 m taperedbeam, with hollowcore precastplanks and in situtopping. 18 weeks 120

    Conclusions1. Reinforced concrete construction

    alternative saves up to 20/m22. Floor construction depth equal or

    less than steel compositescheme.

    LONG-SPAN OFFICEDEVELOPMENTSeven-storey, shell and corebuilding, providing office anddealing room space, with basementcar park, health club and publichouse. Total floor area ofsuperstructure 22,500 m2.

    External cladding in granite panelson precast concrete backing units.The building layout based on an18 x 6 m column grid.

    1 18m 1 18m 1 18m 1

    TYPICAL FLOOR PLAN

    SECTION A-A

  • BROADGATE PHASES 9 & 10 R

    Summary of an appraisal carried outon a major officedevelopment byBovis-Schal for RosehaughStanhope Developments.

    Eight-storey shell and core buildingwith office, trading room, retail areas,plus two level basement car park.Total floor area of superstructure38,000 m2.

    External cladding is pigmentedprecast concrete with pre-assembledglazing panels.

    Steel scheme Frame costSteel frame with (f/m*)composite metal/in situ concretedeck, plusfirespray 25 weeks 111.5

    Concrete schemePrecast soffit slaband ribbed beamswith in situconcrete spinebeams. 25 weeks 90.0

    f

    9m

    . .

    . .

    . .

    2

    1

    B1

    B2

    SECTION

    .

    ConclusionPLAN (typical level)

    obvious choice.

    Published byBritish Cement AssociationWexham Springs, Slough SL3 6PLTelephone: Fulmer (028 16) 2727Fax: (028 16) 2251 Telex: 848352

    Broadgate Phases 9 & 10, LondonClient: Rosehaugh Stanhope Developments and British Rail Joint VentureComposite frame, 8 storey, 4000 m2 per week

  • THE FUTUREWith the demands and continueddevelopment of computer, communica-tion and information technology, thereis an increasing need for buildings to bespecified more precisely by the client.

    It is safe to assume that internalrefurbishment may be needed onceif not twice within the life of the newbuilding. Recladding may also beneeded to keep pace with futurebusiness requirements.

    Design solutions therefore need toreconcile more then just the aestheticsof the building. Improved methods ofdesign and construction of concrete-framed buildings, the scope offered byhigher strength materials and theavailability of prefabricatedcomponents combine to provideflexibility for the user without losingsight of current building requirements.

    But in construction, there is also onemaxim that can never be disregarded -Time is Money. Early completion of aproject means early rental income,minimum on-site costs and reducedrisk of change in the market before thebuilding has been completed.

    Speed of execution in the design, aswell as the procurement and theconstruction of a project, will certainlycontinue to dictate the choice offraming systems in the years to come.The reinforced concrete framingsolution offers the widest range ofbuilding options. Specifying a precast,in situ or composite concrete systemwill ensure that the project meets thecriteria on speed of construction.

    The small selection of projectsillustrated in this brochure, and thecase studies enclosed, demonstratejust what can be achieved -in termsof speed, cost and flexibility inspatial planning.

    Harbour Exchange, Isle of Dogs, LondonClient: Charter GroupIn situ post tensioned frame, 17 storey,3000 m2 per week

  • REINFORCEDCONCRETE

    con@rete