Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Background of The Invention
This invention relates to improvements in domed
building structures.
The prior art has provided numerous forms of roof
structures. Passive self-supporting structures include
the cast-in-place shell structures of Luigi Nervi, which
structures require extensive and complex forms and staging
thus giving rise to substantial construction costs. Other
passive structures include the elegant but complex
lattice-work geodesic domes and cupolas as designed by
Buckminister Fuller, the well known American designer.
Other domed structures have been formed of wood, sheet
metal, fibre glass and the like. Most of these structures
require additional frame supports or panel stiffeners
and/or special means for attaching the panels together
thus giving rise to high installation costs.
Active roof supports include flexible air
pressure supported domes made from air impervious fabrics
or from thin sheets of stainless steel. Such structures
have and are being used in large buildings such as sports
stadiums, hockey rinks and the like. The disadvantages
include high installation/operating costs due to the need
for energy consuming blower systems to maintain air
pressure, air lock doors etcO as well as the ever present
2~ danger of structural collapse in the event the thin roof
material is pierced or torn by a moving object and/or the
blower systems or air locXs ~ail. A collapse of this
nature, especially when the roof is carrying a substantial
snow load, can produce disasterous results.
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Summary of the Invention
It is an object of the invention to provide a
domed, passive, self-supportiny building struc~ure ~hich
can be erected with a minimum of stagings and supports,
and which building structure employs prefabricated
structural units which are identical to one another.
Because of the repetition of components, the costs of
forms etc. are relatively low. Also because of the
repeti~ion of identical components, erection on site is
facilitated, again leading to reduced overall costs. The
teachings of the invention can be used in a wide range of
sizes of building structures, from relatively small domes
of eg. 100 ft. diameter up to 600 ft. diameter or even
more.
Accordingly, the present invention in one aspect
provides a domed self-supporting frameless building
structure comprising a plurality of monolithic, precast,
elongated, concrete panels arranged in abutting edge to
edge relationship with one another such that the panels
are under compressive loadings in both the longitudinal
and lateral directions, the longitudinal edges of each of
such panels coinciding with imaginary lines of longitude
of a spherical or sphere-like shape; there being a
plurality of circumferential courses of such panels with
the panels of an~ one such course being in abutting
end-to-end relation with the panels of the next adjacent
course, and a tension ring surrounding the lower extremity
of such dome and the lowermo~t ends of the panels of a
lowermost said course being in abutting relation with said
ring thereby to assist in securing said panels together in
said abutting edge to edge relationship.
Further aspects of the invention will become
apparent from the following description of a preferred
embodiment of æame taken in conjunction with the appended
claims.
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Brief Descrip~ion of The Drawings
In drawings which illustrate an embodiment of the
invention:
Fig. 1 is a perspective view of a domed skructure
according to the present invention;
Fig. 2 is a plan view of a group of dome segments
as they would appeax if laid out f lat,
Fig. 3 is a sec~ion view taken along line 3-3 of
Fig. 2 showing the panel structure;
Fig. 4 is a section view taken along line 4-4 of
Fig. 1 and showing the tension ring;
Fig. 5 is a section view taken along line 5-5 of
Fig. l;
Fig. 6 is a section view taken along line 6-6 of
Fig. 1 and showing the joint between panels;
Fig. 7 is a section view taken along line 6 6 of
Fig. 1 and showing an alternative form of joint;
Fig. 8 is a somewhat simplified view illustrating
the erection procedure;
Fiy. 9 is a section view taken along line 9-9 of
Fig. 1 showing the joint between adjacent panel ends;
Fig. 10 is a fragmentary view of the dome surface
showing an alternative a rangement wherein the joints
between adjacent panel ends are staggered;
Fig. 11 is a longitudinal section view of one of
the panels showing insulation and roofing in combination
therewith;
Fig. 12 is a vertical section through a hockey
arena incorporating the invention;
Fig. 13 is a plan view of the arena of Fig. 12
but with the roof removed.
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Detailed Description of Preferred Embodiment
Referring now to the drawings there is shown at
Fig. 1 a semi-spherical dome 10 incorporating the
principles of the invention. The dome i5 self-supporting
i.e. frameless. The dome 10 is essentially made up of a
series of monolithic concrete panels 12 arranged in
abutting edge-to-edge relation to one another with the
panels 12 being under compressive loadings in both the
longitudinal and transverse directions. The longitudinal
edges 14 of the panels coincide with imaginary lines of
longitude of the semi-spherical shape. In this example,
there are shown three circumferential courses of panels
i.e. a bottom course 16, an intermediate course 18 and a
top course 20. The panels of each course 16, 18, 20 are
in abutting end-to-end relation with the panels of the
next adjacent course, such panel courses meeting along
circumferential lines of latitude of the semi-spherical
shape. A tension ring 22 circumscribes the lower
extremity of the dome and the lower ends of the panels of
the bottom course are in abutting relation therewith.
Ring 22 thus reacts against the downward and outward
thrusts imposed by the panels 12 and hence serves to
maintain the panels 1~ in their respective positions.
As seen from Fi~s. 1 and 2 only three di~ferent
panel sizes are required in this example, the panel size
decreasing as one goes from the bottom course 16, to the
intermediate course 18 and thence to the top course 20.
In the embodiment shown the panels 12 are sinyle curved,
i.e. curved along their lengths, to match the dome's
spherical surface but flat in the lateral direction.
However it will be understood that the panels 12 can be
double curved, i.e. curved in the lateral direction as
well, to better conform to the spherical surface defined
by the dome as a whole, if required.
Each panel is provided with a waffle-like pattern
on its lower surface which defines a ~eries of
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longitudinal ribs 24 and a series of trangverse ribs 26.
The ribs provide extra strength and rigidity, thes~ being
supplemented by means of reinforcing rods or prestressed
strand 28 embedded in the longitudinal ribs 24, such
reinforcing 28 preferably being tensioned to provide a
pre-stressed final product. The panels may also
incorporate a wire mesh reinforcing grid (not shown) which
extends throughout the entire extent of the upper layer of
the panel. The total panel depth, measured at the
marginal ribs 24, depends on the total panel span.
Panel thickness, including stiffening ribs, may be from
about 1.0 to 2 feet for total panel length of 16 to about
70 feet respectively. Panel thickness between the ribs is
preferably from 1.5 to 2 inches. The concrete used may be
the standard 150 lb./cu. ft. variety or the light weight
120 lb/cu. ft. variety. The panel width is determined by
weight considerations i.e. truck and/or crane capacity.
Suggested maximum width is presently 10 to 12 feet.
By using prestressed reinforcing the panels 14
can be made relatively long thus reducing the number of
panel courses and reducing scaffolding and erection time.
It should be noted that in the completed structure the
dome essentially acts as a "thin shell" with the panels 12
in compression so that the panel reinforcing is not used
to any extent i.e. it is essentially redundant except for
buckling and eccentric loading conditions. However it
increases the safety factor of the dome and enables point
loads and snow loads to be withstood without panel failure.
With reference to Figs. 3 and 6 it will be seen
that the longitudinal edges of panels 12 are provided with
a step-like recess 32 therein and running the full length
of same. When the outer extremities 34 of ribs 24 contact
each other in abutting relation, the recesses 32 together
define a U-shaped-in-section recess 36 which receives a
grouting compound 40 which completely fills the recess.
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Hairpin or U-shaped reinforcing bar portions ~2 extending
outwardly of the panel edges at spaced intervals are
secured in the grouting compound 40 and serve ~o secure
the panels 12 together.
An alternative form of joint between the
longitudinal edges of panels 12 is shown in Fig. 7. Each
panel again includes a step-like recesss extending
therealong except that here such stepped portions fit
together in a ship-lap configuration so that one panel, at
least temporarily during construction, supports the
other. (This would permit erection of panels without
scaffolding after initial ring beam panel erection is
complete.) Again, a U-shaped recess 36 is provided which
is filled with grouting compound 40, the latter engaging
the reinforcing bar portions 42 as before.
The joint configuration at the abutting ends of
adjacent panels (Fig. 9) is similar to that of Fig. 7. A
U-shaped recess 46 is defined between them which is filled
with grouting 48, with reinforcing bar loop portions 50
engaging in the grouting 48 and helping to secure the
panels together. The step-like portions 52, 54 fit
together in ship-lap fashion with the end of lower panel
12 supporting the end of the next upper panel 12. This
feature is of importance during erection procedures as it
reduces the amount of scaffolding needed.
Referring to the tension ring 22 (Figs. 4 ~ 8)
there is shown a pre-cast segmental trough 60. The trough
sections are set in place, such as on the upper ends of
concrete columns or piles 62 which may extend above ground
level G a desired distance. The reinforcing bars are then
put in place within the trough and suitably lapped. (Such
reinforcing may be in the form of po6t-tensioning if
desired whereby to keep the ring 22 in compression). The
segmental trough 60 is filled with concrete 61, which
surrounds the rein~orcing~
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After the tension ring 22 has been completed,
erection of panels 12 can ~ake place. A suitable crane or
hoist (not shown), lifts the individual panels up and
lowers them down so that the lower ends of same abu~
against the sloping annular seat por~ion 62 defined on
ring 22 while the upper ends of the panels rest on ring
scaffold 64 or tilt post supports. After all panels of
the bottom course have been put into place, the
longitudinal joints (Fig. 6 or 7) are grouted and allowed
to cure. Following this ~he next course of panels is laid
in place using essentially the same procedure, and so on,
until the uppermost course of panels has been properly
positioned and the joint grouting cured following which
the interior scaffolding may be removed, at which point
the entire dome structure behaves as a "thin shell" i.e.
with all the panels 12 in compression.
With reference to Fig. 5 there is shown a typical
example of a structure. The length of the first panel
couxse is 17.5 meters while that of the next two courses
is 12.0 meters each. The diameter of the central top
opening is 6.0 meters and the overall height of the dome
structure is 15.3 meters. The radial distance from the
central axis of the structure to the perimeter is 40.80
meters. These dimensions are illustrative only and not
limiting as the invention permits a wide variety of
building sizes to be constructed.
With further references to Fig. 5, the spring
angle A should be kept between about 40 and 52. When
the angle is less than 40 the buckling forces on the
panels increase substantially as does the ten~ion in
ring 22. At angles greater than 52 the headroom becomes
excessive thus leading to a less economical design.
In order to further reinforce the dome structure,
reinforcing bars or strand could be placed in the
longitudinal joints between the panels 12 before grouting
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to increase the safety actor. Also, circumferential
strands or reinforcing bars could be placed in the joints
between the adjacent ends of the panels before groutiny
for the same reason.
A modification of the structure is shown in
Fig. 10. Here the joints 66 between adjacent panel ends
are staggered. This has the advantage that the panels 12
of the first course serve as a guide in the placement of
the panels 12 of the next course (and can support them
when proper ship-lap edges are provided. This would
eliminate some interior scaffolding).
Fig. 11 illustrates the roofing technique. After
the panels 12 have been all laid in place, a layer 70 of
mastic material is supplied to the dome surface to provide
a vapor barrier and air seal. Following this, sheets of
rigid foam insulation 72 are laid on the surface and held
in place with clips 74. A top weather resistant membrane
76 such as SARNAFIL is then applied in known fashion to
complete the roofing procedureO
Completed building structures are shown in Figs.
12 and 13. As seen in Fig. 12 the dome 10 is provided
with a top vent housing 80 which could contain mechanical
equipment eg. a venting fan (not shown)~ The building
structure is shown as housing side-by-side ice hockey
rinks together with bleachers and the other amenities
usually associated with hocXey rinks. Many other uses for
the building are contemplated such as field houses, soccer
facilities, football, curling rinks, tennis, basketball or
volleyball courts, arenas for cattle shows and auctions,
circus performances, stage shows and the like.
The building structure described has many
advantages over other types of domed structures. The
structure described provides a passive, long span roof
(without need of interior columns) using concrete in its
most efficient mode of use - under compression, with all
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its inherent properties including durability, ~ire
resistance and low maintenance. Because of the repetition
of the components, (each course of panels having all
identical units), forming costs are relatively low thus
lowering the overall building cost. The interior waffling
on the panel allows substantial strength with low weight
and such waffled structura additionally provides acoustic
(sound absorbing) benefits as well. The exterior
insulation provides for a "warm" support structure which
does not require thermal expansion joints and the like and
a valuable heat or cold "sink". The same basic design can
be used to provide a wide range of sizes of buildings.
The precast concrete components can be plant produced
locally using local materials and services. Erection
techniques are very simple and rapid erection is made
possible. Minimum on-site construction time should permit
dome erection to be completed in only three or four weeks
of time.
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