Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD FOR REMOVING SNOW FROM DOME SURFACE OF LARGE
SPATIAL BUILDING WITH FILM DOME
Thls inventlon relates to a snow-removing method
for the use of a large spatial building with a film
dome, which is built for the purpose of application to
facilities for sports in an area of high snowfall, and
aims to alleviate a snow load and save energy at the
time of melting of snow by speedily removing the snow
which lies on the surface of a film dome before the film
dome is covered with a large quantity of snow.
BACKGROUND OF THE INVENTION
Recen-tly, there are many cases where a large
spatial building with a film dome is built for the use
of facilities for sports and meeting places even in an
area of high snowfall.
When that kind of large spatial building with a
film dome is built in the area of high snowfall, a
measure to removal of the snow which lies on the film
dome is an important problem.
Conventionally, as for that kind of measures to
removal of the snow, use has been generally made of a
method comprislng the step of melting the snow which
lies on a film dome having a double structure consisting
of upper and lower films by making the film dome warm
with hot air passed through be-tween the upper and lower
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films of -the film dome to thereby remove th,e snow.
That kind of method is merely used for melting
the snow which lies on the film dome and any snow-
removing work is not performed with artlficial means.
Further, the fac-t that it ls not possible to
slide down the snow lying on the film dome well by
merely making the film dome warm with hot air is
established by various experiments conducted up to now
by the present applicant.
The above fact is recognized for the reason that,
even i.f the snow lying on the dome surface melts, water
resulting from melting of the snow is partly absorbed
in the snow without overflowing into a portion between
the snow and the film dome and simultaneously flows down
along the dome surface.
SUMMARY OF THE INVENTION
The present invention relates to a snow-removing
method for the use of a large spatial building with a
film dome constructed by providing a film stretched
between upper chord members of a roof of truss, which
comprises the steps of forming a water film on the
surface of a film by melting all of the snow lying on
the film surface by making the film warm with hot air
blown off through a plurality of hot air supply openings
provided in the upper chord members made of steel pipes
or melting only the snow lying on the bo-ttom into the
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form of sherbet simultaneously with a perlod of time
when snow begins to fall or after a fixed quantity of
snow has lain on the film surface, then temporarily
stopping the blowoff of hot air to completely freeze
over the water film or sherbet-like snow portion,
subsequently mel-ting the frozen portion by making the
film warm again with the hot air blown off through the
hot air supply openings after a Eixed quantity of snow
has lain on the frozen portion, and -thereby sliding down
the snow lying on the film surface therealong to remove
the snow from the film surface.
According to this snow-removing method, it is
possible to perEorm a snow-removing work before a large
quantity of snow lies on the dome surface, so that the
film dome may be maintained to be always in a state free
from snow.
- Accordingly, in its struc-tural design, a snow
load may be remarkably reduced and economical design may
be attained such as to lessen the section of a member as
small as possible, for example.
Further, it is not necessary to perform the
running of an air-conditioning over a long period of
time as much as from a half day to all day long.
Therefore, since the purpose for conditioning of air may
be sufficiently achieved with its running in an
extremely short period of time down to as low as four
hours, the running cost may be remarkably reduced and
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the quan-tity of heat may be lessened to thereby improve
the energy saving.
Furthermore, the snow lying on the film surface
in a short period of time may be removed and -the film
surface may be main-tained to be always in a state free
from snow to thereby enable the na-tural lightening at
all times and serve as a prevention against dew
condensation.
OBJECT OF T~IE INVENTION
It is an object of the present invention to
provide a snow-removing method for the use of a large
spatial building with a film dome which permits
alleviation of a snow load and saving of energy at the
time of melting of snow by positively and speedily
removing the snow which lies on the film dome before the
film dome is covered with a large quanti-ty of snow.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view showing the entire
constitution of a film dome of a large spatial building
with a film dome;
Fig. 2 is a fragmentary perspective view showing
the structure of a film dome serving as an experiment
apparatus; and
Fig. 3 is a fragmentary enlarged-scale
perspective vlew showing the dome.
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DETAILED DESCRI'PTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
Hereinafter will be explained a snow-removing
method for the use of a large spatial building with a
film dome according to the present invention with
reference to the illustrated embodiment.
According to the snow-removing method in the
present invention, a film dome is so structured as shown
in Figs. 1 through 3.
Fig. 1 is a view showing the entire constitution
of an actual film dome of the large spatial building
with a film domei Fig. 2 is a perspective view showing
the structure of a dome serving as an experiment
apparatus; and Fig. 3 is a sectional view showing the
same.
The structure of the film dome will now be
explained in detall. In Figures, reference numeral 1
designates an upper chord membér, 2 a compound member,
and both of these members constitute a part of a
structural body constituting the frame of a film dome.
Use is made of steel pipes as the upper chord
members 1, 1. A plurality of hot air supply openings
3, ... are formed in each side surface of the upper
chord members 1, 1 at regular intervals in the
longitudinal direction of the upper chord members 1, 1.
Further, it is so structured that hot air is
passed through the upper chord members 1, 1 to blow off
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inside a film 4 which will be later described, through
the supply openings 3, ... The supply openings 3, ...
are directed to be substantlally in parallel to the film
4 so as to prevent the ho-t air from directly blowing
against the film 4.
Reference numeral 4 designates a film, with which
the entire dome surface is covered.
The film 4 is fixed to the upper chord members 1,
1 and a center of the film is pressed downward by means
of a pressure cable 5.
Accordingly, the film 4 is stre-tched between left
and right upper chord members 1, 1 in the form of V in
section to provide a subs-tantially V-shaped groove 6 in
section adapted to slide the snow down and formed
between the left and right upper chord members 1, 1 as
extending over the entire length thereof.
As a result, the snow which lies on the surface
of the film dome comes to easily slide through the
groove 6 down to the ground.
Further, it is so structured that the dome
inclination of the entire film dome may be freely varied
at a desired angle (about O to 45).
In subsequence, the~snow-removing method of the
present invention will be explained.
(1) First, a water film is formed on the surface of
the film 4 by getting the film surface wet. There are
two ways of forming the water film on the surface of the
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film 4. As for a first way, there is provided a method,
in which the snow immediately after having lain on the
surface of the film 4 is melted by making the film 4
warm with hot air blown off through a plurality of hot
air supply openings 3, ... simultaneously wi-th a period
of time when the snow beings to fall to thereby
uniformly get the surface of the film 4 wet, and then
the blowoff of hot air is stopped when the surface of
the film 4 sufficiently comes to be we-t.
As a second way, there is provided a method, in
which the snow lying on the bo-ttom is melted into the
form of sherbet by making the film 4 warm with hot air
blown off through the hot air supply openings 3, ...
after a fixed quanti-ty of snow has lain on the surface
of the film 4, and then the blowoff of hot air is
stopped when the surface of the film 4 sufficiently
comes to be wet. Further, about 6.8m/s will suffice for
the average flow speed of hot air in this case.
Further, a tempera-ture difference be-tween the
temperature at the blowoff time of hot air and room
temperature is preferably set to be within the range of
12 to 17C. Further, the range of about 100 to 250
kal/m h will suffice for the quantity of heat -to be fed
in the neighborhood of the film 4.
(2) Subsequently, the surface of the film 4 is left
alone for a while under the condition that the blowoff
of hot air is stopped to then completely freeze over the
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water film of the film 4 and sherbet-like snow portion.
(3) Then, the frozen portion on the surface of the
film 4 is melted by making -the film 4 warm agai.n with
the hot air blown off through -the hot air supply
openings 3, ...
When the frozen portion on the surface of the
film 4 begins to melt down, the snow lying on the film 4
gradually melts and starts sliding at once to thereby
fall down -to the ground through the groove 6.
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