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7/27/2019 FVN Presentation2 Eng

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RECOMMENDATION FOR COST EFFECTIVE PT SOLUTION& ENSURE QUALITY OF PT WORK.

U-SILK CITY, HANOIKeangNam landmark, HANOICity Garden, HCM



CONTENTS :

Economic advantages

Ensure quality & durability of project

Recommendation & Action of Freyssinet

Discussion & Experience exchange for better control quality of PT slabin Vietnam

POSTENSIONED (PT) SLAB



PT SLAB SYSTEM

SCOPE OF APPLICATION

8m 9m 10m7m 11m6m

PT

RC

Cost

RC: Reinforced Concrete Slab

PT: Postensioned Slab

Span

ECONOMY

Cost Comparison Exponential saving for spans > 7.3m



Reduce height of storey

3.1m instead of 3.3 or 3.5m

Reduce concrete, rebar quantity

for column, RC wall, partition

wall, finishing.

Reduce foundation’s materialdue to less gravity loading, less

lateral load : wind, seism

Flat slab give aesthetics, moreflexibility of space dividing.

Reduce M&E fee

Save energy

PT SLAB SYSTEM

TECHNICAL & ECONOMIC ADVANTAGES :



Formwork, rebar : simple toinstall

Faster to build

Cheaper

PT SLAB SYSTEM

TECHNICAL & ECONOMIC ADVANTAGES :



In term of law, we haven’t considered it as conditioned business yet like for

example : construction of basement and underground work.

In term of contractor’s capacity : because PT slab is just recently popular in

Vietnam, so there are only few professional contractors who can guarantee quality

and sustainability of PT slab.

Regarding design & build’s capacity : there is no certificate of sufficient design &build’s capacity as in other developed countries

Regarding design code : there is no Vietnamese code for PT design, we normally

use foreign code : AS, ACI, BS, EC2

There is no certified anchorage system. Any anchorage proposed by contractor can

be used so price decide the choice of contractor.

Quality control depend totally to PT contractors

HOW WE ARE CONTROLING QUALITY OF PT SLAB ?

PT SLAB SYSTEM

Status of use in Vietnam :



-Thi Nai Bridge(Binh Dinh province)inaugurated in 2006.

On 19-Nov-2011, 04 tendons were broken, so

they must limit weight of truck less than 15

tons during reparation

REASON : Quality control is no good:

contractor buy material, install tendon

without strictly surveillance

PT SLAB SYSTEM

Situation in Vietnam :

EXPERIENCE OF BRIDGE IN VIETNAM (Applied post tensioned more than 20 years)

-Rao bridge in Haiphong collapsed in 1988 due to tendon break.

- Project of rebuild of 148 weak bridges along National Road 1A (with funding from

JICA) among which there are many bridges built less than 20 years. One important

reason is the corrosion of tendon.



Experiences in the past In 70 - 80s of last century, there are problems in many bridges due to corrosion of

tendons. Even Ministry of transportation in England prohibited the use of PT

structures in 1992. the ban only be removed in 1996 after serious investigation/

study in all aspect to have preventive measure such as revising of design code,execution criteria, certified PT systems and PT contractor...

Requirement to control quality

& durability of project

Reports of FIB (International

Federation for Structural Concrete)

over view of global situation, thecase of Germany, United State,

France, England, Japan, Canada

PT SLAB SYSTEM

Durability problem



What does leading Organizations of postensioned structure do for durable of PT

structural( EOTA,FIB,PTI).

Review all aspect from :

Design : multi protective layers (Design code)

Materials :

9 Tensile element (strand,wire...by material code)

9 Anchorage system & accessories ( The system must be pre- certified) Execution ( Specification/Method statement)

9 Packing, Transportation, Storage, handling

9 Equipment, Installation, Stressing

9 Grouting

Personnel, workers for PT work must have certificate

PT SLAB SYSTEM

Durability problem




PT SLAB SYSTEM



Point of view

Pt-tendons are structural elements decisive for the functioning of pt-structures

It need strict quality control of design, material & personnel.

It should be executed by specialist contractor

PT SLAB SYSTEM




Authority Management

Should consider PT structure is conditional business which require capacity,

experience :

9 Design capacity

9 Specialist equipments, machines, personnel

9 Professional liability insurance

9Anchorage system is recommended by international organizations of PT structure(such as PTI, FIP, EOTA) or approved by similar tests.

PT SLAB SYSTEM




Design code:

Should have Vietnamese design code for PT structure.

It should use foreign code and revise. We propose to use Eurocode (similar to using

AASHTO and transform to Vietnamese standard for infrastructure design)

PT SLAB SYSTEM




Material criteria:

Tendon is conformed to ASTM A416, BS5896

Anchorage system: It should be certified and

tested system not only separated items as we are

doing

We recommend to use ETAG 013 which guide

detail and require strictly quality.

PT SLAB SYSTEM




Source: Post-Tensioning Institute of Australia (PTIA) http://www.ptia.org.au



Annually organize seminar about design & build PT structure with design consultant,

contractor, client to improve PT technique knowledge

Continue convincing people to consider PT slab is special item which need specialist

contractor.

Convince client to choose Design & Build contractor for PT slab

Share experience about longterm durability of PT structure.

We can support technical specification which show detail of work and requirement to

control durability of project

PT SLAB SYSTEM

Action of Freyssinet



LET’S SHARE YOUR IDEA TO CONTROL BETTER QUALITY OF POSTENSIONEDSTRUCTURE

THANK YOU!

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