DC PT Contractors Role Responsibilities PTIA IEAust Newcastle

7/25/2019 DC PT Contractors Role Responsibilities PTIA IEAust Newcastle

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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.

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DC PT Contractors Role Responsibilities PTIA IEAust Newcastle