The Reinforcement Of The Vorbunker

The reinforcement of the bunker ceiling was probably carried out as follows:
First of all, the columns which were impeding the construction work were taken apart and removed from the building site. The dance floor was then removed in addition to the fifty centimetre high column bases which extended through the air cushion to the ceiling of the bunker. This was necessary as remains of the column bases would have created structural weaknesses in the new roof. In the next step, two layers of double T girders were layed directly on top of the bunker ceiling.The spaces between the girders were filled with fine concrete until a smooth surface had been created. After the concrete hardened, the remaining 20 cm were filled with unreinforced concrete. After the concrete had hardened, the columns were returned to their original locations.