DYWIDAG Post-Tensioning System using Bars
The components of the DYWIDAG Bar System are manufactured in the United States exclusively by DYWIDAG-Systems International. Used worldwide since 1965, the system provides a simple, rugged method of efficiently applying prestress force to a wide variety of structural applications including post-tensioned concrete as well as rock and soil anchor systems.
Available in 1 (26.5 mm), 1 1/4 (32 mm) and 1 3/8 (36 mm), THREADBAR® are hot rolled and proof stressed alloy steel conforming to ASTM A722 CAN/CSA (G279-M1982). The 1 3/4 (46 mm), 2 1/2 (66 mm) and 3 (75mm) nominal diameter bar is cold drawn quenched and tempered alloy steel which after threading also conforms to the strength properties specified in A722.
The DYWIDAG THREADBAR® prestressing steel has a continuous rolled-in pattern of thread-like deformations along its entire length. More durable than machined threads, the deformations allow anchorages and couplers to thread onto the THREADBAR® at any point. The 1 3/4 (46mm), 2 1/2 (66mm) and 3 (75mm) bar can be cold threaded for its entire length or, if enhanced bond is not required, the bars can be supplied with threaded ends only.
The strength of the DYWIDAG anchorages and couplers exceeds the requirements of ACI 318 and the PTI Acceptance Standards for Post- Tensioning Systems.
Bars may also be galvanized. Epoxy coating is the preferred method. Test reports are available for the principal components of the system. Conforming to the requirements of ASTM A722, the deformations develop an effective bond with cement or resin grout. The continuous thread simplifies stressing. Lift-off readings may be taken at any time prior to grouting and the prestress force increased or decreased as required without causing any damage.
The DYWIDAG Bar System is primarily used for grouted construction. In addition, they are sometimes used as external tendons with various types of corrosion protection.
All system components are designed to be fully integrated for quick and simple field assembly. Duct, duct transitions, grout sleeves and grout tubes all feature thread type connections. Tendon duct can be metal or plastic. Galvanized or epoxy coated accessories that thread over the coated bar are available.
Placing DYWIDAG THREADBAR® anchorages is simplified by the use of reusable plastic pocket formers. Used at each stressing end, the truncated, cone-shaped pocket former can extend through, or butt up against the form bulkhead.
THREADBAR® is available in mill lengths to 60' (18.3 m), and may be cut to specified lengths before shipment to the job site. Where circumstances warrant, the THREADBARS® may be shipped to the job site in mill lengths for field cutting with a portable friction saw or coupled to extend a previously stressed bar.
Cold threaded 1 3/4 (46 mm), 2 1/2 (66 mm) and 3 (75mm) diameter are available in lengths up to 45 feet.