7.1.3.2 Manufacturing of anchor plates with headed studs

Headed studs are welded onto steel plates by stud welding with arc stud welding to DIN EN ISO 14555 [84] using barrier gas or ceramic ferrules.

The welding contractors concerned must hold appropriate welding certificates to DIN 18800-7 [85] extended for bolt welding to DIN EN 14555.

Ensuring that welded joints meet quality requirements is carried out in accordance with the provisions of DIN EN ISO 14555 in conjunction with DIN EN 3834 [86].

For anchor plates which are stressed in the direction of thickness, the requirements of KTA 3205-2 [82], Table 7-1 on pre-heating welding areas must be observed.

7.1.3.3 Installing anchor plates on site

Anchor plates must be installed by skilled personnel in accordance with formwork or specific installation drawings. Suitable steps must be taken to prevent them shifting during concreting, such as being bolted or nailed to the formwork.

The tack welds are often observed being used between headed studs and reinforcement but this is not permitted. Spot welding may cause local brittleness and softening of the material the studs are made of, and this may also lead to unwanted notch effects.

When placing anchor plates within the formwork and the reinforcement cage, care must be taken to ensure that the headed studs and the reinforcement are in the right position. In particular, back-tying reinforcement must be installed as specified in drawings, observing carefully the anchoring lengths shown. Adequate spacing is required to avoid cavities or shrink holes in the load induction area.

With horizontally fixed embedded parts, there is a risk of air penetrating during pouring, so the General Technical Approvals require ventilation bores to be made from an edge length of 400 x 400 mm. As feeding in fresh concrete under a horizontal anchor plate from one side is not a reliable method of avoiding air inclusions, it is advisable to provide ventilation bores from edge lengths as little as 200 x 200 mm.

Checks must be made to ensure that anchor plates are correctly installed and that reinforcement is in the right position, with installation records as evidence.