Knowledge-sharing session on tension reinforcement

The second knowledge-sharing session took place on Wednesday 16 May. At the "Hof van Praet Car Park" site in Aalter, a presentation was given on the topic of "tension reinforcement".


Our task is to build a covered public car park with a square overlaying the roof plate. The entire area needs to be accessible to the fire brigade.

Due to the underground car park’s tight execution deadline and the high loads on the roof of the car park, a decision was made to reinforce the roof plate.

Following tension reinforcement, steel cables are also laid across the floor. These cables run along the bending moments in the plate.

Each cable consists of seven strands and has a passive anchor that is embedded in the plate and an active anchor that is inserted through the formwork. All total, 220 cables were embedded in the concrete of the car park’s roof plate.

Once the plate is sufficiently strong following the placement of concrete, the cables are stressed with a jack on the active anchor. On average, hardening may already be complete after one week’s time. Each strand is stressed by a force of 22 tonnes.

The plate can immediately be removed from the formwork following post-tensioning of the strands, which is incredibly beneficial when it comes to scheduling.

Due to the optimum reinforcement-to-concrete ratio, the support structure can be kept lean, even under high loads.

This made it possible to limit the roof plate’s thickness to 30cm, making additional girders unnecessary.