Starter bars in shear walls

The need to construct co-linear or vertical shear walls in different phases arises quite often. Most of the times the starter bars are placed in the traditional way i.e. by extending the horizon-tal rebars of the first shear wall towards the direction of the shear wall that will be constructed in a following phase.

In the cases where the new shear wall will be perpendicular or co-linear with the old one and the starter bars will cause problems in further excavations or they will 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 en-cased in a standardized steel or in an impromptu (e.g. made out of polystyrene) thin box,

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

(c) after the formworks removal, the starter bars are once again centerlined. If the encase box is an impromptu construction, it is removed.

(d) the second shear wall is constructed

This technique is used either for vertical or collinear shear walls. It is ideal when constructing a partial foundation by an excavating and concrete pouring sequence. This is used when there is danger for the adjacent building. We excavate a part of the common edge and we concrete the shear wall and its foundation. Then we excavate the next part and so on.