Detail english 2015-11-12

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9 10 11
eral stability, the upper and lower edges are
bent at an angle. The rigid connections of
the individual lamellae are achieved with
one or two pairs of bolts at each point of intersection
(ill. 3).
Differences from Zollinger system
The Zollinger system and the lamella halls of
Junkers are related in their triangulated and
lattice-grid structural make-up. As barrelvaulted
forms of construction, they are also
subject to the structural need for a rigid
cross-section. The difference between the
two can be seen in the node points, the construction
of which varies considerably because
of the materials used – wood and
steel. In the case of the Zollinger system,
the ends of two diagonal bars meet offset to
each other on each side of a continuing
member and are fixed with a bolt. The bar
they abut extends on, terminating at the next
node (ill. 2).
The rigidity of this form of construction is
achieved solely by the bars continuing
through the nodes. In addition, the loadbearing
capacity of the Zollinger system depends
on the bracing effect of the roof
sheathing. In 1928, the legal battle over
Zollinger’s accusation of plagiarism was
ended with a declaration that the two forms
of construction differed from each other
considerably in their structural details. Subject
to political pressure, Zollinger backed
down and agreed to an economic collaboration
under the name of Junkers-Zollbau.
Ongoing technical development
While the Treaty of Versailles imposed tight
economic constraints on German industry,
around 1924, Junkers was able to set up a
company in Turkey. In order not to have to
hand over the erection of the production
plant to a third party, he instructed the company’s
building management – which was
absorbed in the steel construction department
in 1926 – to optimize the lamella-hall
type technically and economically in such a
way that it could be shipped as a modular
system within a few months and erected virtually
anywhere within the shortest of time.
The springboard for the further development
of these structures was the “Benzinschuppen”,
mentioned previously. In a working report,
Paulssen described its load-bearing
behaviour as follows: “The main load is
borne by the diagonal lamellae, while the
linking members would seem to be scarcely
subject to loading.” In terms of stress distribution,
the structure was further optimized
by adopting the form of a barrel vault. In the
longitudinal direction of a shell structure of
this kind, only very small forces occur, because
there is no curvature in that direction.
The logical outcome of this was the use of
much more slender purlins (ill. 16). Above
all, though, it resulted in an important structural
advantage, allowing a clear simplification
of the connection points and a reduction
of the geometry to no more than single
lamellae. It was no longer necessary, therefore
to connect six oblique members, but
only four.
Using this modified system, two further prototypes
were erected at the Dessau works,
where they were successfully tested and
approved for production. In order to manufacture
the large numbers required for the
Turkish site – at least ten halls – a pressing
apparatus was specially developed (ill. 10).
In 1926–27, at three locations in Turkey,
large-area production halls were erected in
the shortest of time.
12
5 Sectional drawing of aircraft hangar type 11,
ca 1929
6 Transporting steel lamellae with freight plane
Junkers W34f, Guinea Airways,
around 1931
7 The “Benzinschuppen” on the Dessau works site,
ca 1925
8 Node detail and top view of “Benzinschuppen”:
from the first patent application for the “bar grid”,
1924
9 Z-, S- and C-sections and lamella junction:
from patent application for lamella for “bar grid”,
1928
10 Axonometric drawing of pressing apparatus;
from the Junkers patent application for
“pressing apparatus for the manufacture of
sheet-metal grid bars”, 1928
11 Transporting steel lamellae with pack animals
around 1926
12 Prototype structure of aircraft hangar type 11 on
Dessau works site around 1929