Lap-splices

Generally, the lap length is not extremely large because the vertical rebars’ diameter is usually small. For a typical diameter Ø10/B500c, the required lap length is equal to 540 mm, for concrete grade C30/37. For welded wire meshes the lap length is the 70%, thus 0.70*540=380 mm for the particular example.

The lapping of the vertical reinforcement placed to the shear walls’ body: there are no stirrups thus the vertical co-linearity of the rebars is not necessary. In walls’ bodies lapping is being done with the use of a simple contact lap-splice parallel to the longitudinal axis of the element.

In case the shear wall has slabs on either side, its rebars can be anchored inside the slabs’ mass and at the same time they can be a part of the required slab support reinforcement.

In the cases where the new shear wall will be perpendicular or aligned with the existing one and the starter bars are bound either to cause problems in further excavations or to be damaged by handling machines, the special technique described below is being used:

(a) The starter bars are shaped like a hair pin, their legs are temporarily bent and they are encased in a standardized steel or in an improvised (e.g. made out of polystyrene) thin box,

(b) The thin box is nailed to the formwork. Then follows the positioning of the first shear wall reinforcement and finally comes the concrete casting,

(c) After the formworks removal, the starter bars are once again straightened. If the encasing box had been an improvised construction, it is removed.

(d) The second shear wall is constructed.