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Category 1: Buildings
The new City Hall in Utrecht, the Netherlands, is
currently under construction immediately next to and
partly above the new Central Station terminal in Utrecht.
Since Utrecht Central Station is the busiest train station
in the Netherlands, it is a unique and complex location.
The south tower of the building is situated directly above
the new public transportation terminal, which is also
currently under construction. It is supported by 5 main
columns, which run through the bus terminal area on
ground level and run through the Central Station on
raised ground level.
The northern part of the building starts on ground level
but the main entrance is situated on raised ground level.
The north tower has a large void over 6 storeys, which
borders a large curved glass facade on the south side.
This curved facade is connected to the floors with a
lattice girder, spanning approx. 26 m. Vertically, the
entrance façade is fully suspended from the walkway
construction on level 6/7.
The offices start from the 1st floor upwards. Throughout
the building there are a large number of voids and inner
areas. A parking basement of 3 levels will be situated
underneath the north tower.
The main bearing structure consists of 3 concrete cores,
a steel structure and structural exterior walls (steel
structure). Above ground level, there are no dilatations
and the superstructure is a single whole ‘unit’.
Therefore, the entire construction provides the stability
for the building.
The core walls and basement walls will be poured in
situ. From the ground floor upwards, the exterior walls
will be built as a steel construction. These exterior walls
consist of columns, girders and diagonals. Together,
these elements provide stability in the exterior walls.
The floors consist of hollow core plates, of which most
have a reinforced compression slab. This slab works
as a diaphragm, which divides the horizontal forces
within the floor between the different stability elements
(concrete cores and steel structure). The reinforcement
in the compression slab is therefore oriented in 2
directions. Through the use of starters connected to
the steel (girders) and the openings in the hollow core
plates and the reinforcement, a structural connection is
created between the steel structure and the floors.
In the places where the compression slab does not
have sufficient capacity, openings for dowels will be
made in the hollow core slab.
In the places where it is not possible to make a
compression slab (locally), steel tie elements will be
used to obtain sufficient structural cohesion.
The diagonals and lattice girders which transfer the
loads are characteristic of the building’s architecture.
The detailing of the nodes (column-girder-diagonal)
must be done within the framework as drawn by the
architect.
The foundation floor is 300 mm thick and has been
poured in situ. Underneath the columns of the north
tower, the footings are 1,500 mm. There are also
footings at the location of the 5 main columns of the
south tower, with an average thickness of 2,500 mm.
The piles for the foundation are round Fundex grout
injection piles with the dimensions of 520/670 mm and
round Tubex grout injection piles with the dimensions
of 762/950 mm. The level of the base of the piles varies
between 26 m –NAP and 31 m –NAP.
Use of Scia Engineer
The entire main bearing structure has been designed
with the finite element program Scia Engineer.
The concrete walls and floors have been entered as 2D
elements. The concrete beams and the steel structure
have been designed with 1D bar elements. The
foundation piles have been entered as springs.
With the calculation model, the entire force distribution
of the main bearing structure has been analysed and
the forces have been determined for the following
engineering process.
The 3D model was also the basis of the calculations for
the construction phase of the project.
The entrance facade was designed with a 3D
Scia Engineer calculation model. This model helped
analyse how this facade would behave with different
load cases compared to the main bearing structure and
how detailing should be adapted accordingly.
Software: Scia Engineer
City Hall - Utrecht, The Netherlands
