Construction method requires bespoke building guidelines
The foundations are the size of two football pitches and four storeys deep. To counter the upwards force of the groundwater, engineers had to re-think the role of the foundations. The solution involved drilling 2,500 foundation piles 30m into the ground to prevent the structure from rising. Then, a rigid waterproof box was created around the entire area. While this was being constructed, groundwater filled the base, so steel reinforcements and the concrete base had to be installed underwater. It was only after this had been done that the structure was drained.
The method was highly innovative and therefore not covered by rules specifying standards for design and construction known as building codes. To develop the necessary design and quality standards and provide guidance for the contractor, our Advanced Technology & Research group established project specific guidelines which could be used in place of a code. Guidance was included on how the foundations could be checked during the underwater construction process. The guidelines were then independently reviewed and verified by Delft University of Technology before construction proceeded. They served as a reference for the building authorities to check all detailing and construction works.
Massive glass façade requires strength and flexibility
Another awe-inspiring feature of the Markthal is the glazed façade. Consisting of steel cables which create a tensioned net onto which glass panels are hung, it is the largest of its kind in Europe. As well as carrying the weight of the glass, the cables have to deflect in the wind. Our Advanced Technology & Research group calculated that a deflection of up to 70cm in high winds needed to be anticipated. This is at least five time larger than allowed for in building codes and even more than that in situations where glass is involved due to the risk of breakage.
Again, no building code could be applied to this feature, so the team adopted a similar process as for the foundations. Having made wide-ranging calculations exploring strength, stiffness and deformation, they created a design document detailing all the aspects of the façade. This was checked and independently verified by TNO, the organisation for applied scientific research in the Netherlands.
The design document had two functions. It was used by the façade contractor as the basis for their detailed engineering and construction work. It was also used by the municipality as a guide to check all design and engineering documents and the construction stages.
Detailed process helps avoid delays during construction
There was an additional benefit for our client from this approach. By producing the independently reviewed project specific guidelines in consultation with the authorities, the process of realisation and permitting proved highly efficient. This prevented delays during the detailed engineering and construction phase.
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