EYED Vault during a troubled construction phase,
when columns of concrete bents were reinforced.
(Photo courtesy of Eiffel/Laubeuf)
with supports of the vaulted concrete concourse that partially
collapsed early on May 23 at the year-old Terminal 2E at Paris
Charles de Gaulle Airport will likely be a focus of investigations
into the cause of the failure, which killed at least four
Roughly 30 meters of the unusual
freestanding vault enclosing the 650-m- long elevated concourse
dropped several meters off its bearings with little warning.
On evidence available at press
time, an independent structural specialist suggested faulty
"It looks like the roof is
an innocent victim, along with the people inside," he
says, requesting anonymity. Noises emanating from nearby structures
warned of continuing instability a day after the fall.
State-owned Aéroports de
Paris (AdP), which was responsible for the architecture and
engineering of the $900-million complex, has not ruled out
demolishing the entire concourse if fundamental faults are
Serving 22 aircraft bridges, the
concourse provides waiting areas in a tubelike space on an
elevated concrete slab parallel to the main terminal building.
It is enclosed in a flat elliptical reinforced-concrete vault,
30 centimeters thick. The vault is heavily perforated with
window openings. A nonstructural aluminum framework supports
glazing above the concrete.
The vault is divided along its
length into 10 sections with gaps in between to let in daylight.
Halfway along the concourse, the vault is interrupted by an
"isthmus" building linked to the main terminal.
The failure occurred immediately next to the isthmus.
Each of the roofs 10 sections
is made of 17 precast concrete vaults, spanning more than
30 m over the concourse. Though not connected structurally
to each other, the 4-m-wide vaults are fixed to previously
cast edge beams running between concrete portal frames rising
from the ground, much like bents.
The beams neoprene bearings,
supplied by Paris-based Freyssinet S.A., are seated on notches
at the outer corners of over 80 concrete bents, spaced along
the concourse. People and vehicles circulate under the bents.
Collapsed section of elliptical vault is near the link
to the main terminal (above, right, area circled) at Paris
Charles de Gaulle Airport. (Photo top left by AP/Wideworld;
above right courtesy of AXYZ/ADP)
Under a $32-million contract, Paris-based
GTM Construction S.A. built the roof on top of supporting
frames. The frames and other substructure formed part of a
separate contract by Hervé S.A., Paris. Both contracts
ran between April 2000 and January 2003. A separate joint
venture of two French contractors installed the external glazing.
GTM erected the 4-m-wide rings
of the vaults symmetrically, with two side elements and one
at the crown, explains an engineer with Vinci Group, the contractors
owner. GTM supported the elements on a rail-mounted frame
until they were stitched together with reinforcing steel and
concrete into spanning shell sections. No structural connections
were made between abutting shell sections.
With AdP ruling out terrorism and
sabotage, construction defects are seen as a possible cause.
AdP concedes that columns had to be additionally reinforced,