Stressing of Post-tensioning Systems

A safe, efficient, and reliable way to stress and destress tendons, with on-site training options.

DYWIDAG has developed a series of jacks and hydraulic pumps in order to efficiently and economically stress its tendons. Versatility is provided by changing devices that make one unit suitable for many different tendon sizes. DYWIDAG jacks have capacities ranging from 56kips/250kN up to 2,191 kips/9,750kN.

DYWIDAG jacks are highly sophisticated, but still easy to operate. They use inner tube bundles with automatic gripping devices that guide the strand safely through the inside of the jack. This feature makes it possible to control the stressing operation with the highest degree of reliability. Minimal wedge seating losses can be achieved with the power seating option. Power seating hydraulically seats the wedges with a predetermined load, individually and simultaneously, rather than relying simply on friction seating. DYWIDAG jacks also make it possible to overstress and release a tendon to compensate for friction losses and maximize the stress level over the tendon length.

Every jack has a pressure relief valve that safely limits hydraulic pressure to prevent overload. To verify the stressing operation, a gauge port is provided directly on the jack.

Stressed tendons can be safely destressed by employing special wedges and a special jack configuration. Hydraulic pumps are generally equipped with a convenient remote control device.

Alternatively, on-site training for the stressing of DYWIDAG and SUSPA post-tensioning systems is also available.

  • Efficient, economical, and versatile tendon stressing for many different tendon sizes

  • Highly sophisticated, easy to operate jacks for improved safety

  • Options for overstressing and release to achieve maximum stresses without overloading

  • Safe destressing provided by a unique jack configuration

  • Remote control for ease of use

  • On-site training available for DYWIDAG and SUSPA post-tensioning systems for long-term cost savings

Stressing jacks

Due to their robust design, DYWIDAG stressing jacks have proven their reliability in rough construction site conditions for decades. In our in-house workshop, the devices are assembled, regularly serviced, repaired as required and calibrated.

DYWIDAG Strand Tendons: stressing jacks are outstanding for their robust design made of hard-chromium plated alloy steel and/or aluminum alloys and cover a wide range of applications. Due to rapidly exchangeable adaptions the stressing jacks can be applied to a wide range of tendon types. A standard automatic gripping device allows easy handling on the construction site. Likewise, it is optionally possible to attach a power seating device for minimizing wedge slip. With special adaptations, the stressing jacks can also be used for destressing tendons.

DYWIDAG Bar Tendons: bar tensioning jacks are designed for easy handling to facilitate and subsequently speed up the tensioning operation. The jacks are coupled via tensioning spindles to the projecting end of the bar tendons behind the nut and are fixed by a tensioning nut. By means of an integrated wrench sleeve with hand ratchet, the nut is force-tightened after the tensioning operation. Thus, slippage is reduced to a minimum. For overhead application or in particularly confined spaces, tensioning jacks with wormgear cylinders are available achieving a high tensioning force despite very low weight.

DYWIDAG Wire Tendons: Carbon fiber reinforced hollow rams provide a good alternative to conventional steel or aluminum tensioning jacks. Direct comparison reveals a weight saving of at least 60%, allowing easier handling during tensioning operations. The lightweight and slim design allows work to be carried out in confined spaces. Despite the lightweight design, CFRP hollow rams are still robust and durable.

North America: Level 1 and Level 2 certification from Post Tensioning Institute

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