Your Project
Technical data of the project
Project title:
A periscope in Fochteloërveen.
Physical Location:
Fochteloërveen on the border of Province of Friesland &
Drenthe.
Site owner:
Stichting Natuurmonumenten
Architect:
ir.
D. de Haan
Engineering office:
ABT Adviesbureau voor Bouwtechniek te Velp.
General contractor:
Bouwbedrijf Doornenbal
& Louwes te Appelscha.
Location:
Fochteloërveen on the border of Province of Friesland
and Drenthe.
Total
weight of the steel structure:
+/- 23000 kg.
Building costs:
+/- 230000 Euro.
Highest point:
+/- 17,5 meter.
Building period:
April 2000 - June 2000.
Short description of the project
Architectural design
In 1997 the foundation Natuurmonumenten decided to
bring back the
marshland of Fochterloo to its original
state. The result is that the marsh is no longer accessible to
visitors, so you can only look at it from the edge. For this
reason one decided to build a tower.
In 1998 architect Dick de Haan ( 1998) designed a tower
with the shape of a big "7".
A big periscope looking over
the marsh. The lower part of the tower leans backwards to
accentuate the shape of the trees. The upper part is like a
telescope coming out of the woods. The bend in the leg
turns over 90 degrees halfway, so it
was necessary to
place two large columns
under the structure.
To
accentuate the periscope effect, the tower has been
closed from the outside by
wooden panels (Western
Europe Softwood).
And when you reach the top, the front
of the periscope has a wall of glass to give the highest
transparency. The highest point of the tower is about 17,5
meter.
Not higher because the tower may not dominate
the trees.
When you are at the highest level, it gives you
the feeling of looking over the marshland of Fochterloo
like a hawk.
Structural aspects.
The idea was to build a structure with large prefabricated
parts to avoid too much damage to the woods. For that
reason the material that has been chosen is steel. So after
making a concrete foundation, the tower can be build by
placing big steel three-dimensional elements on top of
each other. The wall has been built up with large wooden
prefabricated panels,
which can be attached to the steel
structure after the erection. As mentioned the structure
has been placed on a large concrete foundation block,
which is supported by four prefabricated concrete piles.
The problem of this structure is the deformation. It is not
only the horizontal and vertical deformation, but also the
rotation,
which is important, because of the slope of the
median. That mainly was the reason to use ESA-Prima Win
for three-dimensional structures. After the
module "3D
frame" the module "Steel Code Check (NEN 6770/6771)"
was used, so it was easy to find out if the unity checks
were OK.
After calculating the steel structure, the foundation block
was calculated by using the module "2D plates" and the
module "Analyse betonnen 2D elementen (NEN 6720)" to
calculate the reinforcement. So it was easy to find out if
and where a basic reinforcement was not enough.
To get a feeling on the deformation and rotations,
different loading combinations
were calculated. To
calculate the rotations it
was important to put the
different levels of
wind loads on different parts of the
structure. Because the structure is like a hollow section,
and torsion is a very big issue for the deformations, it was
very important to design stiff frames on the most sensitive
places of the structure.
Using ESA-Prima Win gives us the
opportunity to analyze the structure to find these sensitive
places and after that to optimize the frames
which are
places in these locations.
Use of ESA-Prima Win
Description of the technical questions to be solved with
ESA-Prima Win:
The structure is like a hollow section, and torsion is a very
big issue for the deformations. So it was very important to
design stiff frames on the
most sensitive places of the
structure.
A description of our experience with ESA-Prima
Win when realising the project:
Using ESA-Prima Win gives us the opportunity to analyze
the structure to find these sensitive places and after that to
optimize the frames which are places in these locations.
Modules used:
3D frame
Steel
Code Check (NEN 6770/6771)
2D plates
Reinforcement Design 2D elementen (NEN 6720)
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