Tendonskabels

Tendonskabels, in civil engineering often referred to as prestressing tendons, are assemblies of high-tensile steel strands or wires used to impose compressive stress in concrete structures. They are typically placed in ducts within the concrete and, after the concrete has gained strength, are tensioned by hydraulic jacks and anchored to transfer the force into the surrounding concrete.

There are two main types of tendonskabels: bonded and unbonded. Bonded tendons are tensioned and then grouted to lock the strands to the concrete, creating a bonded system where the prestressing force is transferred along the length of the tendon. Unbonded tendons are protected by sheathing and lubrication and are not grouted to the concrete; they can still be tensioned after casting, but their interaction with the surrounding concrete is different and they behave more like a frictional link rather than a fully bonded element.

Materials used for tendonskabels are typically high-tensile steel strands or wires designed to withstand substantial prestress. The configuration may involve multiple strands grouped into a tendon, which can be straight or curved to suit the element’s geometry. The choice between bonded and unbonded systems depends on factors such as span length, load requirements, constructability, and long-term durability considerations.

Applications of tendonskabels are widespread in post-tensioned concrete elements, including slab systems, beams, bridges, parking structures, and other long-span or thin-walled components. The use of prestressing allows longer spans, reduced material use, improved crack control, and enhanced durability under service loads.

Design and installation follow national or international standards and involve careful attention to duct integrity, anchorage systems, grout quality (for bonded systems), corrosion protection, and regular inspection to ensure structural performance and safety.