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Mono strand system
Flat tendon system
Multi strand system
External Prestessing


Multistrand flat duct - bonded tendon systems

The multistrand flat duct systems is normally adopted for bonded tendon. The strands are individually gripped in one flat anchor head unit and tramsmits their prestressing forces by means of flat type anchor plate casting unit. The strands are stressed individually by means of a mono strand jack. The strands are contained in one flat duct which is made of corrugated galvanized or non-galvanized metal. To ensure corrosion protection and to give adequate bond strength, the tendons are filled with suitable cement grout mix after complete stressing of the strands.

Stressing anchorage data

Strand Dia 0.5 (12.7mm)   0.6 (15.2mm)  
Tendon Type 305 405 505 206 306 406
No. of strand 3 4 5 2 3 4
Anchor Head Type SF305 SF405 SF505 SF206 SF306 SF406
Anchor Plate Casting Type SF305/206 SF405/306 SF505/406 SF305/206 SF405/306 SF505/406
Ultimate tensile force per tendon, KN 558 744 930 558 837 1,116
Stressing force at 0.8 U.T.S.,KN 446 595 744 446 670 892
Flat duct inside
dimension /mm. x mm.
63.5 x 20
or 50 x 20
63.5 x 20 76.5 x 20 63.5 x 20
or 50 x 20
63.5 x 20 76.5 x 20
Jack Type V16 V16 V16 V24 V24 V24

The same anchorage for stressing anchorage can be used as dead end anchorage in which case the wedges are preseated in the anchor head unit by applying nominal force to the strand using the stressing jack.

Alternatively a bulb dead end anchorage can be used with simpler solution and more cost effective. In this case each strand is formed into a bulb shape by means of special bulb forming jack.

Burstling reinforcement should be provided at the anchorage zone for both stressing anchorage and dead end anchorage type.

Dead end anchorage

1. Bulb dead end
2. P.C. strand
3. Grout vent with mastic seal tape
4. Corrugated metal flat duct
5. Burstling reinforcement

Mono strand stressing jack

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PBL GROUP LTD. PBL Group Building 8/11 Soi Vipavadi 44 Vipavadi Rangsit Road, Jatujak, Bangkok 10900
Tel. 66(0)2562-0765-9, 66(0)2941-1692-3 Fax. 66(0)2562-0764 PBLGROUP@PBL-Thailand.com