The shoring bar (19) has a connection bar (21) fastened to ends of the shoring bar and extending transverse to the shoring bar. The connection bar is arranged at a lower end of a fastening element i.e. flange plate. Two ends of a fastening element are arranged for fastening to a complementary retaining element of carriages (13-16). The shoring bar and the connection bar are formed by metal profiles. The fastening element is provided with throughholes for connection screws.
