INNOVATIVE CONNECTING SYSTEM FOR PRECAST CONCRETE · PDF file ·...

INNOVATIVE CONNECTING SYSTEM FOR PRECASTCONCRETE PLANKS ON A MAJOR SPORTS STADIUM

Mary Hardie1, Graham Miller2 and Karen Manley3

ABSTRACT

Close integration of supply and design enabled the delivery of major material and labour cost savingsat Suncorp Stadium in Brisbane. An integrated documentation and construction contract format per-mitted the use of polystyrene voided concrete planks with reliable composite connections to support-ing steel beams. This system was substituted for in situ concrete beams and slabs previously assessedas the lowest cost option by the project quantity surveyor. A development of technology previouslyused in bridge building, the “Clever Plank” system allowed the elimination of in situ formwork withits attendant time, cost and safety disadvantages. Robust linkages were achieved between the supplierand the central project participants. Confidence in the detailed design enabled the production of theplanks to commence before full testing of the prototype for code compliance was complete. This pro-ject represents an example of efficiencies achieved by minimising “flow activities” and concentratingon value-added “conversions” in accordance with lean production principles.

KEY WORDS

Precast concrete, Composite connections, Innovation.

INTRODUCTION

The BRITE Project (Building Research Innova-tion Technology and Environment) was estab-lished by the Australian Cooperative ResearchCentre for Construction Innovation to foster theincidence and quality of innovation in the Austra-lian Property and Construction Industry. The pro-ject seeks to redress industry scepticism about thebenefits of innovation through demonstration andbenchmarking activities. Case studies of success-ful innovations are recounted and this informationis widely disseminated in the industry and thebroader community. The case studies are intendedto demonstrate best practice and contribute to theenhancement of industry capabilities. Among thesix case studies produced in 2004 was one on theprecast plank system used for the redevelopmentof Lang Park, now known as Suncorp Stadium inBrisbane. This case study demonstrates anapproach compatible with lean construction prin-

ciples. Through the close integration of supplyand design activity, savings were made in cost andtime parameters while at the same time reducingthe occupational health and safety risks associatedwith the construction. The form of contract andthe strong linkages between the precast supplierand the other project participants enabled theadaptation of a technology previously used inbridge building for use in a sports stadium. Theengineer’s calculations and the supplier’s experi-ence enabled them to have confidence in the solu-tion produced to the extent that they were able tocommence production of the precast planks forthe stadium before full testing of the prototypewas complete. Construction time was shortenedwith no loss of quality or safety. Responsibilityfor monitoring the process was shared by the con-tractor, the supplier and the consultants. Thisenabled the lean construction principle of mini-mising flow activities while maximising value-

Prefabrication, Assembly and Open Building

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1 Research Associate, School of Construction, Property and Planning, University of Western Sydney, Locked Bag1797, Penrith South, NSW, 1797. Phone +61 0 9852 4323, FAX +61 0 9852 4300, [email protected]

2 Associate Professor, School of Construction, Property and Planning, University of Western Sydney, Locked Bag1797, Penrith South, NSW, 1797. Phone +61 0 9852 4315, FAX +61 0 9852 4300, [email protected]

3 Research Fellow, School of Construction Management and Property, Queensland University of technology,GPO Box 2434 Brisbane Qld 4001. Phone +61 7 3864 1762, [email protected]

added transformations to be put into practice(Alarcon 1997).

CASE STUDY

Suncorp Stadium is a 52,500 seat modern footballstadium constructed as a redevelopment on thesite of the rundown and inadequately servicedLang Park football ground formerly known as“the Cauldron” in Brisbane, Queensland (seeFigure 1 overleaf). The project was constructed bya private sector joint venture under a managingcontractor. The procurement system was a twostage, document and construct contract with aguaranteed maximum price. As the name implies,a document and construct contract does notinclude initial design concept but does involve thefull documentation of the project under the man-agement of a head contractor. Such a contractallows the flexibility for new construction solu-tions to be introduced by the builder, who is notlimited by the technical systems envisioned by theconcept designer.

The stadium opened in July 2003 and wasdelivered on time and within budget. Both theorganisational and the technological systems thatwere followed enhanced the need for innovativesolutions. Risks and benefits were managed for amore equitable sharing than would have occurred

through a traditional procurement process. Thisenabled the main contractor to develop innovativetechnical solutions not envisaged in the conceptdesign which produced both cost and time econo-mies.

INFLUENCE OF PROCUREMENT FORM

The traditional system of building procurementand the attitudes associated with it can form animpediment to the introduction of innovativeideas and products inhibiting the spread of leanconstruction principles. Both top down andbottom up innovations are hindered by the pre-vailing theory of construction (Koskela andVrijhoef 2000). Top down innovation can be pre-vented by the split authority paths and lack ofsupply chain integration often seen in construc-tion projects. Bottom up innovation can bestopped by lack of incentive for project basedworkers to produce gains from which they do notthemselves derive benefit and by the failure tocollect information learned on one project for usein future projects.

Contractual systems are being developed whichaddress some of these difficulties an attempt tomake the building delivery process more efficient.Currently a transition phase exists between thetraditional contractual system with its competitive

Proceedings IGLC-13, July 2005, Sydney, Australia

464 Innovative connecting system for precast concrete planks on a major sports stadium

Figure 1: Suncorp Stadium Photo Montage (Image copyright Ken Keefer provided by Arup)

and adversarial base and new hybrid procurementsystems which attempt to share both benefits andrisks more equitably (Pryke 2004).

The development of the precast plank compos-ite construction solution for Suncorp Stadiumarose in part from the opportunities for designerand contractor interaction inherent in the procure-ment system adopted for the project. Under the“Document and Construct” contract used, thejoint venture contractors were encouraged to lookfor alternative forms of construction rather thanbeing restricted by those envisaged by the conceptdesigner. This is in contrast to the traditional lumpsum fully documented type contract where gener-ally all design decisions are made before the con-tractor becomes involved. In this case, thepreliminary stadium design envisaged conven-tionally formed in-situ reinforced concrete beamsand slabs. This had been assessed by the project’squantity surveyor as the lowest cost option. Whenthe joint venture contractors were appointed theychose to pursue the idea of a composite steel beamand plank design based on the likely advantagesrelated to construction time and risk managementof the subcontractors. Consulting engineers inves-tigated the feasibility of the composite approachand found that while the components were moreexpensive for the beam and plank composite con-struction, the savings resulting from the lack offormwork and scaffolding were considerable. Itwas this factor that eventually influenced the deci-sion to adopt the composite system. The contrac-tor’s interest in achieving savings was driven bythe form of contract which allowed for the sharingof the benefits if the project was delivered belowits guaranteed maximum price. This contractualarrangement created an atmosphere where inno-vative solutions were explored and embraced.

CLOSE INTEGRATION OF DESIGN ANDSUPPLY

The value adding and time savings that resultfrom following lean construction principles canbe illustrated through the Suncorp Stadium casestudy. The consulting engineers and the supplierworked closely together to produce a solution thatmet the performance criteria for the stadium by ameans not previously used in such structures inAustralia. The two main elements of thissystem—the polystyrene voided planks and theformed rebate detail—have only been combinedto our knowledge on a few occasions globally inthe building industry. The particular planks sup-plied for the project and the particular rebatedetail designed by the engineer are unique to theStadium project and have resulted in substantialbenefits (Manley 2004). Discussions between the

consulting engineers and the supplier resulted in asolution achieving considerable benefits over theuse of in-situ reinforced concrete slabs and beams.The composite system chosen generated savingsof A$260,000 in steelwork costs (equating toapproximately 8% of the steelwork cost) andA$70,000 in labour costs when compared to pre-cast concrete voided planks with conventionalconnections to steel beams. The use of thesevoided precast “clever planks” reduced the weightof the Stadium grandstand steel floor beams byapproximately 25% due to the efficiencies gener-ated by the composite connection between beamsand planks. The connection detail enabled theconcrete topping to be placed free of cracks andconsequently removed the need for rework torepair cracks. The time savings made contributedto the successful delivery of the project on timeand within budget after a two year documentationand construction program.

ROBUST LINKAGES

The integration of the supply chain achieved inthis project provided significant dividends for allparticipants. The nature of the contract and therobust connections between consultants and sup-pliers enabled the production of a mutually bene-ficial solution and allowed a local Australian firmto become a global technology leader. Tradition-ally Australian construction industry supplychains have been fragmented and lacking in clearcommitment to the success of the overall project.Often individual firms in the supply chain practisedefensive blame shifting to minimise their ownlevel of risk (Miller et al. 2002). This situation iswidely perceived as unsatisfactory and supplychain integration is seen by several authors as auseful strategy for the construction industry(Arbulu et al. 2003; Briscoe et al. 2004; Dainty etal. 2001a; Dainty et al. 2001b; Hollingworth2002; London and Kenley 2001; Nicolini et al.2001; Palaneeswaran et al. 2003). In the case ofSuncorp Stadium, the relationships between theprecast plank supplier, the consulting engineersand the main contractor were sufficiently inte-grated to permit the exploration and selection ofan innovative construction solution to the benefitof all concerned.

ADAPTIVE DEVELOPMENT OF BRIDGETECHNOLOGY

A study of the steel and precast plank optionsidentified significant potential savings if a reliablemethod of achieving a composite connectionbetween the planks and beams could be found.There would be a considerable saving in the


Mary Hardie, Graham Miller and Karen Manley 465

weight of the steel beams required and thereforetheir cost and associated supporting structure.Such systems were known to be used in bridgeconstruction and after extensive research, theengineers devised an innovative rebate design forthe planks which would enable a composite con-nection in the proposed structure. Formed rebatesin the precast plank edge allowed for a solid andreliable connection to the supporting steelwork(see figs. 2 & 3). By extrapolating from availabletheory and existing codes the engineers calculatedthe theoretical capacity of the composite joints.They arranged for the testing of a full scale proto-type of the system to verify the accuracy of theircalculations. This testing was done by the Schoolof Civil Engineering at Queensland University ofTechnology (Davies 2002). The exigencies of theconstruction program, however, necessitated thatthe manufacture of the planks should commencebefore the prototype testing was complete. As thedesigners were confident that the results would bepositive, manufacture was commenced prior tothe completion of the testing. Subsequent testingverified their confidence as has the performanceof the planks and composite connections in opera-tion in the stadium. There has been no evidence of

movement, nor any need for rework to repaircracking in the concrete topping.

The testing of the prototype planks can be seenas a "flow" activity. Such "flow activities" do notnecessarily add value to the project. As Ballardand Howell (2004) explain, flow activities canlead to "work waiting on workers" or "workerswaiting on work". Progress can be impeded evenif construction methods are adequate. Carefulwork scheduling is essential if potential savingsare not to be lost. The confidence that the designengineers had in their own analysis of the struc-tural performance of the composite system was



Figure 2: Detail of Composite Connection(Source S. Davies, Arup)

Figure 3: Precast planks being placed ready for composite connection (Source S. Davies, Arup)

such that they were able to take the risk of pro-ceeding before full confirmation of the measur-able performance of the prototype system wasavailable. The decision to manage early produc-tion and prototype testing as parallel processeswas a conscious effort to maximise the efficientdelivery of the en product to the client. AsBertelsen (2004) points out "construction is a spe-cial kind of production" and that a change is afootwhere construction is moving from an activityprocess to a system for delivering a product. Thisshift in focus is driven by more robust linkagesbetween the various players in the constructionprocess and by a need for the efficiencies thatsupply chain integration is able to produce (Loveet al. 2004).

REMOVAL OF THE FORMWORK TRADE

Formwork for reinforced concrete is both materialand labour intensive. The advantages of removingthe need for formwork included a less congestedconstruction site without the large number ofworkers required to produce in-situ formwork andthe resulting reduced car parking and concretetruck access problems in an inner city location. In

addition, the risk of concreter delays or disputeswhich could hold up the work of the followingtrades were minimised or eliminated. Past historyof industrial action in the highly unionised con-creting trades was influential in the decision-making process. The areas under the grandstandswere able to be kept free of temporary proppingnecessary for formwork so later trades did nothave to deal with restricted access caused by prop-ping obstructions. Finally, in-situ concrete poursinvolve a relatively high level of occupationalhealth and safety risk. The potential for formworkcollapse during pouring is something that requiresconsiderable input in terms of quality control andchecking to ensure that reinforcement is correctlyplaced and plywood forms and supporting struc-tures are adequately propped during the pour.Transferring large parts of the quality controlissue offsite to a factory location where the pre-cast planks were manufactured enabled easier andmore satisfactory levels of control which enabledperformance standards to be guaranteed by thesupplier.

Of course such advantages could have beengained through use of precasting in a more con-ventional and non-composite construction



Figure 4: Stadium under construction (Source S. Davies, Arup)

system, but the consulting engineers lookedbeyond the possible savings in the formworktrades in response to the contractor’s quest toachieve greater savings.

LEAN CONSTRUCTION

As defined by Alarcon (1997) "Lean Construc-tion" involves project management to minimise"flow" activities or those which do not add valueto the project while maximising those "transfor-mations" which do add value. Lean constructionprinciples grew out of the lean production theoryinitially developed by Ohno at the Toyota MotorCar Company (Ohno 1988). The Toyota Produc-tion System involved achieving continuous pro-duction flow through monitoring measures whichreduced inventory and were capable of rapidresponse (Conte and Gransberg 2001). Theseideas were applied to construction through thework of Koskela (Koskela 1992). Koskelaemphasised the importance of production processflow and the need to characterise the process by itspropensity to add value. Ballard and Howell havedefined the four roots of a lean constructionapproach to be: the Toyota Production System;dissatisfaction with project performance; estab-lishing a theoretical foundation for project man-agement; and the discovery of facts that currentpractice finds impossible to explain (Ballard andHowell 2004). While the theory of lean construc-tion has developed a significant following amongconstruction academics and some practitioners ithas yet to be thoroughly embraced throughout theindustry as a whole. Where lean construction isoccurring the principles of lean construction areoften adopted implicitly rather than explicitly.The case study described in this paper is an exam-ple of lean principles being practiced without anyexplicit adopting of the theory by those involvedin the construction process.

The experience on Suncorp Stadium serves asan illustration of the achievements that are possi-ble in a lean construction atmosphere. While theparticipants did not set out to apply lean produc-tion theory to construction practice they have,nevertheless implicitly understood the need tominimise non value adding activities and maxi-mise the kinds of transformations that deliver asatisfactory end product to the client. This con-firms that lean production principles can be putinto place without explicit adoption of lean con-struction theory. As Howell explains lean con-struction aims to meet customer needs while usingless resources (Howell 1999). As such, it isentirely compatible with systems that aim toimprove the quality of the delivered product to theconsumer and the public generally.

The issue of the relationship between lean con-struction and human resource management hasbeen raised by (Green 2002). He suggests thatlean construction will repeat the mistakes of "pre-vious instrumentalist improvement recipes" if itfails to give considered attention to this area. Theconstruction industry has not tended to be anindustry that encouraged suggestions and contri-butions from all levels of its participants. Itsnature has been very largely hierarchical. Innova-tion theory, however, is making impacts in thisstructure and more construction companies areseeing the benefit of encouraging an atmospherewhere new ideas are welcomed rather than sup-pressed (Bossink 2004; Gann 2000; Slaughter2000). Such organisations are seeking a balancebetween production efficiency and humanresource management. It would appear that thereis no reason why lean construction principlescannot incorporate such a balance.

CONCLUSION

The Suncorp Stadium project is evidence of thesignificant savings in both labour and materialsthat can be achieved through the integration ofsupply and design. The procurement systemadopted by the client enabled the considerationand incorporation of innovative construction solu-tions that were not part of the initial conceptdesign. The joint venture contractor was notlocked in to an inflexible design solution selectedbefore they were able to have any input. The con-sulting engineers for the project were specificallyasked to research alternative means of fabricatingthe grandstands in order to produce cost andscheduling efficiencies. The process led to aninnovative composite construction system beingdeveloped to connect voided precast planks andsteel beams. The system enabled a 25% reductionin the weight of the steelwork used to support theprecast concrete planks with resulting cost sav-ings over standard precast plank systems. It alsomeant the elimination of some of the complica-tions of in-situ concrete work which was origi-nally considered the most cost effective option.The composite precast system had quality controlbenefits and site organisation benefits whichmade it the preferred option and produced signifi-cant savings. Integration of the various membersof the project team meant that they were confidentenough to produce a new solution and to back thatsolution with there own expertise and reputation.To do so they needed to be assured of adequatequality control throughout the supply chain for theplanks. The project required and demonstrated thevalue of a contractual system that distributes thebenefits of cost savings to those who produce the



savings, thereby providing the necessary incen-tive to find new solutions. As such the case studyis an example of successful practice of lean con-struction principles if not an overt espousal of leanconstruction theory. Future projects are likely tobenefit from the experience gained and fromapplying the principles and techniques of leanconstruction in a more systematic way.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the contri-bution of the Lang Park Redevelopment JointVenture, HOK Sport and PDT Architects, Arupand Quickcell Technologies for information andassistance in compiling this paper.

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