144
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Category 2: Civil Structures
The Weesperbrug is located south-east of Amsterdam
and dates back to 1937. The bridge has the total
length of 144 m, with a main span of 96 m. The bridge
crosses the Amsterdam-Rhine Canal. The Amsterdam-
Rhine Canal is one of the main waterways in the
Netherlands. The canal is an important connection
between the port of Amsterdam and the Ruhr in
Germany, making it one of the busiest inland canals
in the world. Rijkswaterstaat, the administrator of the
canal, put out a request for a tender for the major
maintenance and strengthening of its steel arch bridges,
to guarantee a residual life of 30 years. The contractor
decided to replace the old bridge with a new one,
instead of pursuing lengthy and risky maintenance
and reinforcement activities. The new bridge will have
an orthotropic steel deck, whereas the old bridge has
a concrete deck. Therefore, the new bridge weighs
considerably less than the old bridge, so the concrete
foundation can be reused.
The Weesperbrug is one of eight bridges in the
maintenance project which will be replaced by the
contractor. The method of exchanging the old for the
new bridge will minimise the nuisance to shipping on the
Amsterdam-Rhine Canal and the environment. The new
Weesperbrug will be constructed at the works of the
contractor in Gorinchem, located at the river Merwede.
This location has an advantage for transportation
because the bridge can be transported across the river,
over the North Sea and through the North Sea Canal to
its final location on the Amsterdam-Rhine Canal.
The use of Scia Engineer
The calculations for the design of the new Weesperbrug
are made using Scia Engineer. Furthermore, the
temporary situations of removing the old bridge and
placing the new one have been analysed.
Different types of models have been made for different
types of verifications. At first a main model has been
made. This model consists of the steel deck in 2D
elements and all the other elements in 1D members.
This basic model is used for:
• Elaboration of forces in the main structure;
• Assessment of the main structure on the strength;
• Assessment of the main girders, arch and pendants
on fatigue;
• Assessment of the (arch) stability;
• Assessment of dynamic (wind) effects on the
pendants.
The arch stability is checked by finding the lowest
buckling mode with corresponding n-value. These are
used to calculate the critical buckling load and the
buckling length, which were used in a buckling check
in accordance with the Eurocode. For the dynamic
wind effects on the pendants, a geometric nonlinear
calculation was made for a realistic value of the stresses
in the pendant at a certain amplitude.
The Weesperbrug has an orthotropic deck structure
consisting of a steel deck plate with troughs as
stiffeners. A sub-model consisting completely of fine-
meshed 2D elements was integrated into the main
model to analyse the fatigue life. To carry out a good
fatigue assessment, influence lines are needed. These
are created with Scia Engineer by placing an axle load
every 40 cm. This is realised by using the function
Traffic Loads (Lane Loads Manager). Furthermore, the
result per load (axle load location) could be exported to
a spreadsheet by using the detailed results in the mesh
node. Finally, the fatigue assessment is realised in the
spreadsheet.
In another sub-model the most important connections
are modelled using 2D elements with a fine mesh.
In this model the strength of these connections is
assessed. Again, the sub-model is integrated into the
main model for realistic preconditions and forces. The
connections checked by using this model are:
• Arch - Pendant
• Pendant - Main girder
• Arch spring - Main girder
Since there is only a couple of hours’ time available to
place the new bridge, it is placed in one piece from a
pontoon on the canal. For some parts of the main girder
this situation gives the largest stresses. In the main
model the supports and loads are changed to verify all
temporary situations.
“Weesperbrug” Arch Bridge - Weesp, The Netherlands
Software: Scia Engineer
