Ahoy, multi purpose hall

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The new entrance to the old sports palace

For Kraaijvanger + Urbis z I worked on the specifications for the renovation and expansion of the Ahoy complex in Rotterdam. The project was in the hands of architect Dirk Jan Postel.

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The project was divided into building parts. I have worked on the new entrance to the sports palace and on the new (tennis) hall at the rear. I was involved until the moment that the contractors started calculating and that contracts could be signed.
The great thing about Kraaijvanger architects was that they had their own financial calculation department which I regularly consulted. We discussed the changes between the final design and the specifications.  It is essential, I think, to keep a finger on the pulse. If things turn out to be more expensive than in a previous phase, you have to cut back on something else. That went very well, and I remember that this part of the project was calculated within budget by the contractor.

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During the work on the large tennis hall one day I realised the influence of a structural design on the pricing of a project. At that time the stabilisation structure on the side wall were still conceived in round columns. The large lenticular beams that span the hall will naturally deform vertically under the influence of the wind. With such constructions, you will soon talk about 10 - 20 cm in the middle of the beam. The constructor informed me that we could win 10 cm deformation if we increased the wall thickness of the columns. A calculation, with the table book in hand, taught me that this decision would mean many, many kilos of extra steel. Since steel is paid by the kilo, we talked about 70K of euros.  For that money, you can make a good detail that can absorb the larger movements.