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Category 2: Civil Structures
Introduction to the Ketelbrug
The Ketelbrug is located at the A6 motorway
crossing Ketelmeer between Lelystad and Urk in the
Netherlands. The bridge has the total span of 800 m. A
bascule bridge is incorporated.
The bridge consists of 2 carriageways, both on separate
bridge decks, with 2 traffic lanes. On the east side there
is also a connection for slow traffic. The height of the
bridge is 13.1 m and it has a movable part on the south
side.
The Ketelbrug is the property of Rijkswaterstaat
(national road authority) and is one of the fourteen steel
bridges which must be strengthened before 2018.
Since being put into service in 1970, the traffic has
increased and the trucks become heavier. This increase
is more than could have been provided for at that
time. The heavier load has caused fatigue in the steel
structure of the bridge. The renovation is intended to
ensure the safety of the bridge deck.
The renovation of the Ketelbrug entails the replacement
of the two moveable bridge decks and both accessory
driving mechanisms, including the electrical systems.
The renovation is in order to continue to guarantee
smooth and safe flow on water and road. The goal
of Rijkswaterstaat is to cause the least possible
disruption for the traffic on the road and waterway. The
replacement of the bridge deck must take place within
a weekend.
The project
The steel structural part of the project consists of
creating a new design for the existing bridge deck. The
new design of the bridge deck must be equal to the
existing one, hence a minimum of modifications was
required to the existing sub-structure. This requirement
leads to a new design within the existing situation. The
new design must be in accordance with the current
regulations (EuroCode).
The deck of the Ketelbrug is an orthotropic steel deck
where the troughs are welded between the girders. The
cross girders span approximately 8 m between the two
main beams. The main girders span approximately 23 m
between the main bearing and the front supports.
The use of Scia Engineer
The design of a bridge with a steel bridge deck is
dominated by the fatigue assessment. For a good
fatigue assessment, a very detailed model is needed.
For this reason, the whole deck, including the counter
weight, is modelled in Scia Engineer. The model is
constructed entirely of plates. Locally, a very fine mesh
is used to get detailed information.
To carry out a good fatigue assessment influence
lines are needed. The influence lines are created with
Scia Engineer by placing an axle load every 40 cm. This
is done 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.
“Ketelbrug” Movable Bridge - Ketelmeer, The Netherlands
Software: Scia Engineer
