Internal Unbonded Post-tensioning System Using Threadbars

A high-performance and reliable solution for infrastructure strengthening and repair.

DYWIDAG’s internal unbonded post-tensioning system using threadbars is the ideal solution for projects where infrastructure needs strengthening and repair. This versatile system can be used in a variety of applications, including the connection between precast members, the fixation or tieback anchorages of steel structures, and transversal post-tensioning.

Our system features two types of threadbars: WR bars with continuous hot-rolled thread, and WS bars with cold-rolled thread at anchorages and couplers. This allows for greater flexibility in design and installation, and ensures a high level of performance and durability. In addition, the bars can be re-stressed to maintain their original design capacity and extend the structure’s service life.

To protect against corrosion, we offer several options for our unbonded bar tendons, including injection with corrosion protection wax or cementitious grout, or heat shrink sleeves or DYNA PROTECT bar (a double-layer, machine-wrapped corrosion protection tape), both supplied with PE ducts. This ensures that our system provides long-lasting performance and requires minimal maintenance over time. The maximum corrosion protection quality is achieved through prefabrication, which is an option for all corrosion protection options. However, on-site options are also available.

  • Threadbars available from 1'' (18mm) to 3'' (47mm)

  • Mainly suited to applications where the tendon profile is mostly straight

  • Low slip anchorages for low losses of pre-stressing force

  • No grouting operations required on site, for faster installation times

  • Bars are inspectable, providing good structural monitoring options

  • Several corrosion protection options available depending on the application: heat shrink sleeve or DYNA Protect® Bar and PE duct

  • Fill with flexible filler or gel

  • Replacement, re-stressing and coupling possible

Main standard for steel nuances

Europe/ Asia/ Latin America: Y1050

North America: Grade 150 ksi


WR Bars

  • Diameter 18-47 mm (Europe)

  • Continuous hot-rolled Thread

  • Specifications in the brochure, page 20

WS Bars

  • Diameter 26-40 mm

  • Cold-rolled Thread on either Side with low slip special Thread

  • Specifications in the brochure, page 21

Europe/ Asia/ Latin America: ETA-05/0123, Z-13.72-50123 (Germany)

North America: Florida DOT approval

Industrial Buildings
Commercial & Residential Buildings