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DC PT Contractors Role Responsibilities PTIA IEAust Newcastle

Feb 28, 2018

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    D&C PT Contractors Role &Responsibilities

    Chris M. Harris

    Contracts Manager, Structural Systems& PTIA Technical Committee

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    Why do PT contractors get involvedin the design of the project to start

    with

    Commercial desire

    S!ecialist engineers, design dra ts!ersons, &design so t#are

    )is* & re#ard allocation

    Time Constructa%ility

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    What are the co!!on efficienciesintroduced to the structure by a PT

    contractor

    (lement thic*nesses

    Su!!ort o!timisation Sla% structure ty!e o!timisation & orm#or* )ein orcement rationalisation

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    What aspects of the e#isting designwill the PT contractor

    review$change

    +e!ends on the ty!e o !ro"ect

    Ie ' Igross or %uildings- Concrete grade ' volume ' thic*ness Structure ty!e lat !late ' lat sla% ' %anded- )estraint design )e%ar content

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    %ure a Tower

    Conforming design )ein orced sla%s

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    %ure a Tower

    Non conforming design PT %ands and sla%s +riving orce TIM(

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    Conclusions

    Pro"ect (ngineers to coordinate #ith

    contractors Involve a PT contractor early

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    PT in buildingsPT is li*ely to %e considered or most !ro"ects.

    I the consultant doesn t consider it, then thecontractors #ill

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    Why PT Savings in materials Savings in construction

    time

    Im!roved dura%ility and

    ro%ustness Cost savings

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    'o!e perceived down sideissues

    Time consuming to design %y theoccasional designer $

    PT a!!lies real orce into a structurehence analysis incl. secondary e ects-needs to %e realistic and s!eci ic.

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    'o!e perceived down sideissues

    System and !rocessneeds to %e understoodand details coordinatedsu iciently

    /inding most economical!ro!ortions o concrete,PT & rein orcement can%e a lengthy iterative!rocess, %ut usually

    yields su%stantial%ene its. So t#are &e !erience is *ey.

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    (ther effects to consider Secondary e ects in all

    indeterminate PTstructures, %ut can %e%ene icial

    Structural movements

    cree!, shrin*age, thermal- Structural restraints

    #alls, sta%ility elements- +ynamic %ehaviour may %e

    a lighter, livelier structure-If doubt exists, talk to a

    specialist PT designer (orthe PTIA)

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    PT design is not differenthowever"""

    ( ective & e icient design does re0uiree !erience With sound engineering *no#ledge and

    !ractice this can %e done success ully. Assistance and guidelines can normally

    %e o%tained rom the s!ecialist contractors

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    Design philosophy

    Consider the generalconce!t o !artially!restressed concrete

    A!!ro!riate!ro!ortions orein orcement and!restressing steelde!ends on thea!!lication restrainedv. unrestrainedconcrete-

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    The D&C route for PT delivery

    The usual variants hereare1

    +&C %y tenderinvitation

    +&C %y alternativedesign

    If D C is expected and

    planned for, timeefficiencies and

    inno!ations can occur

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    D&C Design )rief A Post Tensioning Design )rief is

    critical or a success ul +&Carrangement.

    It should ocus on the !er ormancere0uirements on the design

    The e tent o +&C area re0uired

    The loads and load !aths

    Mem%er si2es #ith acce!tance tolerances

    Servicea%ility and dura%ility re0uirements

    Movements and 3ointing strategy

    +e ine the +esign, certi ication & a!!roval!rocess

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    Perfor!ance re*uire!entsAs ar as !ossi%le indicate1 Architectural re0uirements tolerances, inishes etc-Site constraints and constructa%ility issuesPour se0uence & any limitations on edge stressing access4imitations o the su!!orting structure.

    Any rame actions that need to %e considered in loor design.( !ected areas o restraint and strategy or its management incl.

    location & ty!es o !our stri!s &'or tem!orary movement "oints &'or!ermanent %uilding "oints.

    )oles and res!onsi%ilities in the design !rocessIns!ections and installation signo s5uality and sa ety re0uirements.

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    Types of PT Contract

    Su!!ly and Install S&I- 6 Structural design, documentation, ins!ection &certi ication %y engineer

    6 Sho! dra#ings, install, 5A %y s!ecialist contractor +esign and Construct +&C-

    6 structural loor design, documentation %y s!ecialistcontractor

    6 Install, ins!ection & certi ication %y s!ecialist contractor 6 (ngineer remains res!onsi%le or vertical elements,stairs, #ind & earth0ua*e design, etc.

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    Design Considerations for PT Price

    Pour Si2eStrand +iameter 7um%er o Strands !er TendonCou!lers

    ( icient A!!roval Process

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    Concrete Properties and Profiles

    Concrete outlines and grade needs to %e!rovided #ith PT !rice or client todetermine total cost o solution.

    8e a#are o concrete testing & strengthre0uirements or initial & inal stressing,these are essential or !er ormance oconcrete & sa ety at PT anchorages.

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    'tructural Design Certificate

    4oads +ura%ility )e0uirements +e lection Criteria

    Analysis Assum!tions

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    Detailed 'cope of Wor

    +esign +elivera%les or +&C, usually1 6 Concrete outlines 6 PT dra#ing design & sho! in one- 6 %ottom rein orcement dra#ing 6 to! rein orcement dra#ing 6 sections & details

    Construction Services

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    Client $ )uilder Responsibilities

    Site Amenities Su!!ly o Po#er and Water 4i ting o our Materials on to the +ec*s Su!!ly and Install o Conventional )ein orcement

    including Studrails #here a!!lica%le Concrete In ill o To! Sur ace Stressing Pans

    Anything else "o% s!eci ic-

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    Contract Conditions

    )e erence to Standard Conditions o Contract )e erence to (8A 9ariation )ates

    Payment Terms )etentions 4i0uidated +amages Insurances

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    Project RelationshipsDeveloper

    +ead Contractor

    ,or!wor 'ub-Contractor

    .rchitect'tructural %ngineer

    Post TensioningD & C

    'ubcontractor

    Reinforce!ent 'upplier 'teel ,i#er Concreter

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    Ti!ely Co-ordinationCo:ordination %et#een1services consultants

    architectstructural engineer %uilder s services alima*s etc-all %y others.

    Co:ordination %et#een1structural engineer !t designshared %y engineer & s!ecialist !t designer.

    Timeliness & in ormation sharing is critical.

    4ate in ormation #ill lead to re:#or* & additional costs./ailure to co:ordinate #ill lead to re:#or* & additional costs.

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    .c nowledge!ents3ohn /air#eather /ran* /ili!!one

    3amie Mac*en2ie#ho are the authors o most o these slides.Ho#ever any errors are mine.