18
X1
Nomination Category 1: Buildings
Introduction
The Congress Centre project for the city of Mons in
Belgium is a “design & build” contract won through an
international competition. The building will be operational
in 2015, when Mons will be the European Capital of
Culture. Situated between the historic centre and the
new suburban zone - which will include a train station
designed by Santiago Calatrava - the Congress Centre
constitutes a focal point for the economic and social
development of Mons. By creating a visual link with the
Beffroi tower, the intention of Studio Daniel Libeskind
architects was for the building to be fully integrated into
the public and cultural urban tissue. This concept, seen
as “urban blossoming”, is reflected in the open spiral form
of the building.
The programme comprises three auditoria seating up to
800 people, multi-purpose halls of up to 1,640 m
2
, offices,
a restaurant, a 158-space underground parking facility
and a viewing platform accessible to the public via a roof
promenade. The project is currently under construction
with a planned completion date in mid-2014.
Structure
The main load bearing structure is formed by curved and
inclined reinforced concrete walls termed “ribbons”, with
their complex geometry following an ascending spiral. As
well as creating a dynamic form, the ribbons are integral
parts of the structure that allow the ground floor volumes
to be uninterrupted by internal columns. They act as deep
beams spanning as much as 28 m between supports and
15 m in cantilever. These ribbons are constructed using a
novel technique of flexible prefabricated formwork panels.
This structural formwork uses expanded metal sheets
to contain the concrete, placed around a double layer
of reinforcement mesh that provides the stiffness to the
panel.
All structural elements are prefabricated to the maximum
extent: whenever possible precast planks or hollow-core
slabs and prefabricated walls are used. For the heavily
loaded roof beams spanning over 25 m, prestressed
beams are used. In order to avoid columns on the
ground floor, the meeting rooms are located on a light
composite slab which is suspended from the curved
ribbon walls. At the tip of the building, the ribbons form a
cantilevering wedge used as a viewing platform. In this
specific location, the ribbons are made of a steel frame.
The building is founded on a series of prefabricated piles
driven into the ground. In order to gain construction time,
pile caps were avoided by using a 40 cm basement slab.
Stability
Due to the inclinations and curvatures of the ribbon
walls, and the fact that the slabs are on different levels
in each zone, overall stability was an important issue.
The structural equilibrium had to be checked both for
the complete structure and the intermediate construction
stages.
Modelling
The complex geometry of the building was a challenge
for the development of both the calculation models and
the execution drawings. Using 3D drafting software, the
curved and inclined surfaces of the ribbon walls were
first modeled as a series of planar panels, reflecting the
way they are constructed. These surfaces could then
be imported into Scia Engineer as planar 2D members
and connected to the slabs, beams and columns of the
project. One important advantage of using 2D members
rather than shells was that all 2D components such as
openings and subregions were available in the Scia
software. Different FEM calculation models were created
in Scia Engineer that allowed for the testing of the
structure at different scales, from the global complete
building to local nodes connecting multiple elements.
Using different settings for the mesh calculation times
were optimised. The ribbon walls were tested both in
individual models with lateral supports at slab locations
and in a global model that takes into account the complex
interaction between the structural elements.
Several features of Scia Engineer were used according
to requirements: the deformations in the concrete were
calculated for the long term according to Eurocode 2, non-
linear calculations were carried out for the steel structure
of the viewing platform and automatic combinations
in accordance with the Eurocodes were used to verify
the concrete and steel elements. Specific models were
also built to test the stability of elements at different
construction stages using props at precise locations.
Software: Scia Engineer
Congress Centre - Mons, Belgium
Nomination Category 1: Buildings
