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X2
Winner Category 2: Civil Structures
Programme
Architectural and stability study
Concept
The design for the Vluchthaven footbridge provides
for an object that stands out for its graciousness and
oneness. In a departure from classical engineering, our
concept was to limit the hierarchy of the elements by
merging several functions together into one whole. The
Vluchthaven bridge is an example of integral design:
the deck, cross members, main beam and the finishing
are one. The bridge is conceived as a single curved and
cutout plate.
Inspired by the elegant movement of a heron’s wing
during flight, the plate is slightly torsed around its axis,
representing the backbone of the bridge. As a result,
the form of the bridge evolves: the cross-section at mid-
span is concave while the opposite happens above the
supports, with the cross-section convex. This way the
necessary constructive height is achieved on supports.
It gives the Vluchthaven bridge its wave shape,
admittedly modest, but sufficient to provide a visual
experience and rhythm.
The bridge’s light wave shape, referring to the light
waves on the IJ lake, is structurally optimally used, and
is continued in the design of the railing. This consists
of a series of vertical elements following the wave. The
absence of horizontal lines in the railing, additionally
accentuates the shape of the bridge deck. This gives
the entire bridge a calm and moderate rhythm. LED
lights are embedded into the railing.
The mobile part of the bridge has been designed
integrally with the bridge. While closed it is hardly
visible.
Structural analysis
Scia Engineer has been used to create an analytical
model of the entire bridge out of 3D plates. There are
mainly seven different types of elements that can be
distinguished in the model:
1. The side, as 3D plates
2. The curved corner plates, as 3D plates
3. The light curved plates for the deck, as 3D plates
4. The U-shaped stiffeners above the abutments, as 2D
plates
5. The flat stiffeners under the deck, as 2D plates
6. The concrete support structures as beams
7. The supports with the stiffnesses of the present
foundation piles
Through the use of the ‘import dxf/dwg’ function, the
3D contour lines of the geometry have been uploaded.
While tracing the imported lines and nodes, the curved
plates were generated in the model.
Making use of a custom XML-tool we modeled the 98
load cases for the traffic loads.
The specific form of the stiffeners above the abutments
could be modeled with the use of the ‘cut-out’ function.
Also the flat stiffeners follow the geometry determined
by the wave of the deck plate above.
Because it is a mobile bridge, along with the closed
situation three open versions have also been modeled
to calculate the effects of the wind on the structure
during the opening and closing.
With the ‘Productivity toolbox’ the entire plate geometry
has been exported in table form into the calculation note
along with all the results of the linear calculations. The
‘stability analysis’ was used to estimate the buckling
behaviour near the support on the complete 3D model.
To investigate the vibratory behaviour of the bridge, the
permanent part of the bridge was analysed with the use
of the ‘Dynamics analysis’ function, using the full 3D
model.
Software: Scia Engineer
“Vluchthaven” Footbridge - Amsterdam, The Netherlands
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Winner Category 2: Civil Structures
Quote of the Jury:
“The jury nominated this project because of the combination of its original
design and its functionality. The moveable part of the bridge is totally integrated in the deck
and is barely visible in the closed state. The bridge fits well in its surroundings. The structural
system consists of a single curved plate merging several functions together, and of concrete
foundation piles without extra supports.”
