Netherlands: high-tech fastening for high-speed track ... - Hilti

Construction
Page 6
Suddenly, everything stopped.
No one milled around the
construction site and the workers
put down their tools. A VIP, complete
with security detail, strode
through the semi-finished arena.
German President Horst Koehler
was looking over the site that has
generated architectural interest
and that only took two-and-onehalf
years to complete.
During the day, the Allianz Arena
looks from afar like a bulbous ceramic
serving dish, and a giant one
at that. The stadium is 259 meters
long, 227 meters wide and 50 meters
high (850 x 745 x 164 ft). To
the visitor, the weaved, gleaming
white façade appears upon closer
inspection as a type of skin. At 0.2
millimeters thickness (.008 in), the
plastic material allows 90 percent
of the light to penetrate while
keeping out rain, hail, wind and
snow without suffering damage.
The skin wraps around a loadbearing
structure totaling 7100
tons of high-strength S355 steel.
48 radially-aligned steel beams
carry the ceiling load to the reinforced
concrete at the outside of
the stadium. Above this a secondary
roof of steel strutting stretches
out. Workers secured with rope and
carabiners crawled along the steel
strands like spiders after President
Koehler had left the building.
Hilti consulting engineer Volker
Römer, who looked after the stadium
site for Hilti together with
Hilti salesman Manfred Dachauer,
redirected attention to something
else. The seemingly light-as-air cocoon
surrounding the stadium consists
of individual, rhomboid-form
foil cushions. There are 2784 of
these cushions that range between
16 and 32 square meters (172 and
344 sq ft) in size and cover a total
area of 64,000 square meters
(688,889 sq ft). The cushions are
fastened to steel netting above the
steel beams. Viewed up-close, the
light appearance of the edge-free
structure gives the ceramic bowl
the look of a round air mattress or
inflatable boat.
The cushions are each outfitted
with as many as eight fluorescent
tubes and color filters, allowing
the frame of the Alliance Arena to
light up in white as well as blue or
red. Hilti was brought in to fasten
the fluorescent tubes. Throughpenetration
of the base steel was
not allowed and the protective
coating could not be damaged.
This was a case for the Hilti X-BT
threaded fastener, a blunt-ended
fastener for setting at short depths
that shows its strength in thin,
coated, high-strength steel. Even a
tensile load of 2 kN, caused by the
leverage exerted by the angle of
fastening in the Allianz Arena, is
no problem for the Hilti X-BT. The
Hilti X-BT was also the right
choice for fastening the brackets
for rainwater pipes to the steel
beams.
Volker Römer had good reason to
climb the stands of the stadium that
hold as many as 66,000 people. To
ensure that the spectators are as
close to the action as possible, the
lower tier of stands rises at 24 degrees,
the middle tier at 30 degrees
and the top tier at 34 degrees. The
seats, as Volker Römer showed, are
anchored in the concrete by Hilti
One coat
is enough
Protection against fire is particularly
important wherever people
congregate. Fireproofs, a German
company specializing in fire
protection, carried out most of
the corresponding work in the Allianz
Arena, mainly using Hilti
products in the process: firestop
jackets for sealing pipe penetration,
firestop foam for sealing cable
penetration and firestop
bricks for light drywall partitions.
Where cables and pipes both cut
through a single opening, Fireproofs’
workers used a mineral
fiber slab that was coated with
Hilti CP 673 firestop paint. This
provided the required firestop
duration in a single coat, and a
dry-film thickness of 0.7 millimeters
(.03 in). This type of strong
performance and efficiency are a
tremendous advantage when
construction schedules are short
and deadlines are tight.