Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
The present invention relates to a method of erecting
arched structures, particularly of relatively large spans
as used, ego for the storing of agricultural products,
for airplane hangars, and the like The invention is
particularly useful where the structure is to be used only
for a limited time and then dismounted and rebuilt at
- another site, as in the case of international fairs.
Conventional methods of building arched structures
indispensably require the use of scaffolding or other
auxiliary means, to support the yet-to-be assembled members
composing the arched structure Such procedure is of
course costly in terms of material ? workmanship and time
BRIEF SUMMERY OF THE INVENTION
It is therefore the major object of the present
invention to provide a method for the above specified
purpose that will overcome the disadvantages of the known
constructing methods.
It is a further object of the invention to provide a
method by which the arched structure will be substantially
self erecting
According to a general aspect of the invention, there
is provided a method of erecting arched structures
consisting of a plurality of rigid structural members,
comprising the steps of lining-up on a flat surface a
series ox said structural members, each member having two
free ends and an apex at a point located above a line drawn
there between, pivotal connecting to each other adjacent
ends of the members loosely tying to each other adjacent
pairs of said apexes by a number of strings of
progressively increasing lengths made of an elastically
deformable material, and erecting the structure into an
arched fox by forcibly closing the distance between the
first- and the last-in-line members.
In practice a plurality of such members are employed
and the said erection operation is maintained until the
longest of each of the said strings associated loath each
pair of the members become elastically taut.
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The strings are preferably made of steel, said
lengths being selected in correlation with the Yield Point
of the steel, and the said longest string will be of a
higher strength than the other strings, and, in fact,
designed in the same manner as applied to tension elements
employed for holding together arched structures of the
conventional type, namely satisfying the static and dynamic
stresses applicable to the construction as a whole.
BRIEF DESCRIPTION OF THE DRAWINGS
These and further constructional details and
advantages of the present invention will become more
clearly understood in the light of the ensuing description
of a preferred embodiment of the invention, given by way of
example only, with reference to the accompanying drawings
wherein:
Fig 1 is a schematic representation of a pair of
stxustural members arranged according to the principles of
the present invention, namely before applying the erecting
force;
Fig 2 is a typical Stress vs. Strain diagram of
different kinds of steel; and
Fig 3 illustrates a complete arched structure
erected according to the method of the present inventor
DESCRIPTION OF A PREFERRED EMBODIMENT
with reverence to Fig 1, there are shown, for sake
of clarity only two structural members in the form of
trusses generally denoted To and T20 The truss To is
hingedly supported by a fixed support So, whereas the truss
To is hingedly supported by a sliding support So. The
trusses are pivot ably connected to each other at joint Jo.
The joint Jo is maintained at a certain higher level ho
than the supports So and So, for a reason to be explained
below.
. Apexes Al and A of the trusses To and To are
connected to each other by three (in this example) strings
or wires I We, and We. As noted from the drawing, the
string I is substantially taut, whereas strings We and We
are of greater lengths and therefore hang noose by a
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progressively increasing amount
Now for better understanding the operational
characteristics of the invention, it will be advisable to
consult the diagram of Fig I This is a typical
Stress-Strain or load versus elongation) representation of
various kinds of steel As is ~ell-known in the art of the
mechanical properties of metal, in accordance with Hooves'
Law, at first the curves hollow a linear portion in which
the deformation is directly proportional to the applied
loan, where the ratio between them is defined as Young
Modulus or the Modulus of Elasticity This linear portion
represent the region of elastic deformation of the steel,
which is then transformed (at the point called the Yield
Point) into a slanting or curved potion representing the
plastic deformation region where the metal looses its
mechanical strength. In practice, using a sufficient safety
coefficient, steels must be used well below their
respective Yield Points.
Now the concept of the present lnvenion is based on
ZOO the intentional overload q of all except one of the
strings I, isle still at every given stage of erection, at
least one of the wires will serve as a load-bearing element
of the structure factually only for supporting the
self-weight of top stxucture)O namely in a progressive,
gradual manner depending on the number of strings employed.
Hence, referring back to Fig I it will be seen that
if a force P is applied to the sliding support So, thus
raising the Joint J1l the wire We is under tension or
tensile force, while the other wires are in a slackened
state. Further approach of the support So in the direction
of the support So will cause additional elongation ox the
wire Wow which will eventually bring it above the elastic
deformation region and beyond the Yield Point, into its
plastic Reformation state The length of the stripy We is
so calculated that it will become tensioned just before the
point where the string We ceases to serve as a loan bearing
element of structure, namely beyond its yield region.
Further erection of the structure will eventually cause the
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complete tearing of the wire We, while string We is about
to undergo the same routine of deformation
It will be thus readily comprehended that by proper
design calculations, taking into account the
characteristics of the steel of which the strings are made,
the number thereof, and the amount by which one string
exceeds the length of the other, this erection routine can
be continued until the final span ox the structure t as
denoted by L in Fig. 1, is reached whereby the string We
lo ultimately assumes its structural function namely to hold
the structure in its arcuate configuration as shown by
broken lines in Fig. 1.
. It will be advisable therefore to make this string We
of an appropriate quality (say, grade III of Fig Al and to
lo satisfy other specifications normally followed for thy
purpose, including the proper safety coefficient ox the.
material and other static and dynamic structural
considerations.
Fig 3 illustrates the operation of the method
according to the invention with a larger number of trusses
To, To, To, ..., To and wires Wow We and We, in an
analogous manner, which need not be further explained.
It has been thus established that the present
invention provides a most efficient way for building arched
I structures with practically no additional equipment or
auxiliary structures as }Nina in connection with
conventional methods.
Furthermore the dismounting of the structure is also
extremely efficient; all that is needed is to release one
30 of the supports, say the sliding support So, from its
final, fixed position (shown in broken lines in Figs. 1 and
I and allow it to slide back towards its initial
position, resulting in the gradual flattening of the arch.
. Those skilled in the art will readily appreciate that
many variations and modifications may be applied to the
conceptual approach of the invention and to the manner it
is to be put into practice. Thus, for example, other forms
of structural elements - besides the truss form - or
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materials other than steel, may be Swede such alterations
should be deemed to fall within the scope of the invention
as defined in and by the appended claims
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