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2019-09-23

Steel Spiral Staircase in Amsterdam, the Netherlands

In 2017, VIC OBDAM was commissioned by BAM to fully design the Kasbank project (total weight about 368.17 t) in Amsterdam. This project included a free-standing steel spiral staircase.

VIC OBDAM is an independent steel construction company that completes complex steel projects from design to installation.

Construction and Design

Design was one of the main challenges in the spiral staircase project. To reach the final design, several intermediate steps were necessary. Multiple models were calculated, taking into account the deformation total in addition to meeting the client’s esthetic wishes. Each model was calculated in structural analysis software RFEM, which made it possible to view critical areas clearly. After each intermediate design step, an optimization step was made which ultimately resulted in the final design.

The staircase structure behaves like a large spiral spring. The handrail is made of glass, which required the deformations to be minimal.

The staircase is suspended from tension members attached to the top floor, which spans between a concrete structure. The fixed supports are located at the bottom of the stairs. The deformation of the top floor was considered, to determine the floor’s bending stiffness influence. This stiffness impacts the tensile force in the tension members.

A dynamic analysis was also performed to determine the structure’s natural frequency. The vibration effects could then be estimated for the spiral staircase.

The element connections were also an important focus to ensure the deformations were minimal. The steel connections’ stiffnesses were analyzed and the rotational stiffness was included in the RFEM model.



Project Specifications

Model data

Number of Nodes 4583
Number of Lines 1274
Number of Members 37
Number of Surfaces 307
Number of Load Cases 8
Number of Load Combinations 23
Number of Result Combinations 2
Total Weight 22.990 tons
Dimensions 34.28 x 30.31 x 44.27 feet
Program Version 5.21.00

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