National Military Museum (NMM)

The roof can be viewed as a spatial framework in the form of a beam grid. This gigantic structure will be 4 metres tall. The problem was that the roof will not be supported on fixed points. This means that the supported roof shape is sometimes a square and sometimes a rectangle. The action of a beam grid is most effective if it can transfer its forces into two directions. The larger the difference between its length and width the more forces are absorbed by the shorter spans only. ABT researched the most optimal ratio between the roof sections. 3D modelling programs such as Evolutionary Structural Optimization (ESO) and GSA were used for this purpose. This involved determining the optimal thickness of each beam. Ultimately 2,000 joints and 90 load-bearing combinations were analysed using optimization scripts. The objective was to avoid using even 1 kilogram of material too much. A drawback of such optimization is that it could adversely affect flexibility of use. In the case of this roof design it was not an issue. The roof offers more freedom, for example in terms of suspending aircraft in areas that deviate from the Statement of Requirements, the output specification of this PPP. The gains realised on the basis of the optimal structure were used to make the design feasible and the architecture exceptional. The special dimension of this project is not only the design, but especially the way in which the entire project came together. As is the case in all new projects contracted by the Netherlands Government Buildings Agency (RGD), a Design, Build, Finance, Maintain and Operate (DBFMO) tender was issued. The contractor in a DBFMO also acts as the developer. ABT was a member of the Heijmans team whose aim was to achieve a totally transparent process. Budget overruns were considered a joint problem, requiring joint solutions to be developed. The aim was not so much to produce the cheapest design, but rather the most interesting design for the client. The ambition was to ‘realise the most exciting museum in the Netherlands’.