Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Tbe present iDvention re~ates to a concrete 6~ab aDd
relates particular~y but ~oot exclu~ivelY to a slab ~hicb is
use~ul as a ~oor or transportab~e buildings.
ID the past, traDsportable bui~di~gs have beeD traD6ported
OD steel, slumiDium, wood or composite bases usually with a
plywood or partic~e board floor on bearers. Structures of
this type a,re proDe to rot, corrode or be eaten by termites.
Further, tbey sound bollow uDderfoot.
It would be preferable iD some areas to provide trans-
10. portable buildiDgs ~ith concrete f]oors. A conveDtioDalcoDcrete ~lab on wbicb a traDsportable buildiDg caD be erected
and lifted is relatively simple. At its destiDatioD such a
slab provides aD extremely durab~e floor.
~ owever, a massive coDcrete base would be subjected to
large acceleratioD forces duriDg transportatioD OD CODVeDtiODa1
trucks whicb would result in cracking o~ tbe slab unless the
slab was adequately EtreDgtbeDed.
A concrete slab for a traDsportable building module,
~bicb could be successfully traDsported, would have to bave
20. sufficieDt strength to support the weigbt o~ tbe buildiDg,
and a sufficiently low weigbt to avoid excessive iDertia
Sorces during acceleration. It is reasonable to expect that
a transportable buildiDg includin~ floor would be cubjected to
up to 2.5 g in t~e vertical directioD, up to lg in the lateral
directioD, aDd up to 3g iD tbe ~oDgitudiDal directioD.
UsiDg coDventional reio~orcing tec~iques a ~hrge
CDDcrete slab may be reinforced throughout its area ~itb
j teosioned 6traDds to g~ve a 6ufficieDtly 6trong 6tructure ~or
i transport~tion. ~nfortunately, a~ the teDsi~Ded straDds must
! 3~ be embedded in ~ufficlent CODCrete to achieve tbe ~ecessary
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1176865
stren~thening effect, the total ~Ei~ht of the slab beco~es so
high that it can not be readily tr~nsported on rough roads using
conventi~nal road transport. As it is necessary for the flcor
slab to be.lignt enough to enable tne finished building mLdule
incorporating the floor, to be loaded:and transported econcmically
using jacks and trailers, whilst.having sufficient reinforcement
to avoid the concrete going into tension without causing static
deflection of the slab, conventionally constructed sl~h~ are not
generally suit~ble in such applications.
~here is therefore a need for an alternative to the
i conventional concrete slab construction which satis~ies at least
$ some and preferably all th~ afore said requirements.
In accord~nce with the present invention there is pro-
. vided a concrete slab which.is pref~rahly square or reckangullr
coM~rising a reinforoed substantially flat area having an under-
~ side and rein~orced edge beams extending around the periphery
¦ of the underside of the substantially flat area.
A transportable building or a transportable building
n~dule comprising a building structure mounted on a unitary,
structural, prefahricated concrete floor slab, in which the
concrete floor slab has a rectangular, reinforced, floor æ ea,
the floor area has a relatively l æ ge longitudinal dimension and a
¦ relatively small lateral dim~nsion, the floor area has a substan-
tially flat upper side and an underside, the floor slab has an
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1~76865
area of at least 34m2~ two integral~ concrete beams e~tend long-
itudinall~ of the concrete floor slab adjacent respect~ve long-
itud~nal sides thereof and depend downwardly from the unders~de
of the floor area, tw~ integral, concrete beams extend laterally
of t~e concrete floor slab adjacen$ respective lateral sides
thereof, and depend downwardly from the underside of the floor
area, said lateral an~ said longitudinal beams including
tension mans extending substantially along the length of the
said be~ms, said tension mans acting on sai~ lateral beams
exerting a conpressive force on each of said lateral bea~s of at
leas$ 120 kilonewtons and said tension m~ans acting on said
longitudinally extending beams exerting a compressive force
on each of said longitudinal keams of at least 400 kilonewtons,
said lateral beams are joined to the longitudinal beams, and
one or more integral, reinforced, concrete stiffenIng ribs extend
across the ooncrete slab between beams, and are joined to CAid
beams, said stiffening ribs depending downwardly frum the
underside of the floor area and being of less depth than any
of t~e keams, the regions between the beams and stiffening
3: 20 ribs being in the form of open, dcwnwardly facing recesses,
the main slab area of the concrete floor slab apart from any
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rein~orcing n~ns or stiffening r~bs, having a thickness between
25mm and 75mm~ the average area per unit weight of the concrete
floor slab being at least 4.2m2/ton, and the arrangement being
such that the transportable bu~lding or transportable buiJd~ng
module can be loaded onto a trailer using jacks, transported
on the trailer, unloaded using jacks and then be free standing
on site.
Preferably, the peripheral edge beams are held under
compression by tensioning means such as pre or post-tensioned
10 reinforcing strands extending longitudinally thereof.
IL Most suitably the tensioned reinforcement for said
edge beams constitutes the major part or substantially all the
tensioned reinforcement in said slab.
- In the case of post-tensioned strands, the strands
are pref~r~hly found only in the edge beams and not elsewhere
in the slab so as to keep weight to a ninimum. However, in
the case of pre-tensi~oned strands, the strands may be loc~ts~
throughout the slab area without und~ly increasing the overall
weight of ~he slab.
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76865
Al60, ~t 1~ preferred ~o inset tbe corDers o~ tbe s~ab
. ~nd to aDchor tSe ten6ioDed 6tra~d~ to plate~ ~ich *raD~fer
tbe load from the 6trands iDto tbe concrete.~ st preferably,
the p~ ates are angle sectioD plates .
TraDsportable buildiDgs are usually constructed iD two
or m~re modules and iD tbis case oDe part o~ tbe fitructure
~ay be coDstructed OD a 61ab iD accordaDce wit~ the present
inveDti~D aDd the other part or parts o~ ~be fitructure con-
6tructed OD a furtber said 6~ab or slabs. T~e slabs are
10. transported separately and placed adjacent to oDe aDother on
site so that the buildiDg sectioDs caD be appropriately
joiDed together. Although the preseDt inveDtioD will be
described with particular refereDce to tra~sportable buildings
it is to be understood that the concreSe ~labs o~ tbe preSeDt
inveDtioD can be used for other purposes. ~or example, they
can be used for f~oors of Dormal site-built buildings such as
houses'or motels.
They are especially useful iD eartbquake prone regioDs
or for soil'stabilisatioD in bad ~oil coDditions. The floor
20. slabs of the preSeDt inveDtioD are particularly useful iD
remote areas ~here DO coDcrete is available.
Also, tbe concrete ~ab of tbe present iDvention could
be used as a f~oor iD a multi-storey buildiDg. ~n this case
a Dumber of the floor 61abs ~ould be ~oined togetber bori-
zoDtally to produce a ~loor of the multi-~torey buildiDg.
The preseDt ~nventioD will DO~ be de~cribed, by way of
example, with re~erence to tbe accompaDyiDg drawings, ~D
~bich:
~ ig. 1 ls ~ plaD view of ~ coDcrete floor sl~b ~D
. accordaDce witb the preseDt i~ventioD;
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1~76865
. Fig. 2 i~ ~ ~ectional vlew along the liDe A-A of
~igure l;
Fig. 3 i~ a ~ecti~nal view along the line ~-B o~
Figure l;
Fig. 4 i6 a side elevation viewed from tbe line C-C
of Figure l;
Fig. 5 is `a partiall~ cuta~ay plan view along the liDe
D-D of Figure 4 ~owiDg iD detail t~e rein~orcement employed
in a corDer of the ~lab of Figure l;
10. Fig. 6 is a partial, cutaway side elevation aloDg tbe
line E-E of Figure 1 ~howiDg in detail tbe reinforcemeDt
employed iD a corner of the ~lab of Figure l;
Fig. 7 is a vertical sectioD through a longitudiDal edge
beam of the ~lab of Figure l;
Fig. 8 is a vertical ~ection through an eDd edge beam of
tbe slab of Figure l;
Fig. 9 is a vertical sectioD through a lateral 6tiffeDer
o~ tbe ~lab of Figure l;
Pig. 10 is a vertical CectiOD through a loDgit~diDal
20. edge beam of a concrete ~lab similar to ~igure 7 witb aD
exterDal recess for receiviDg a ~all of a bouse;
Fig. 11 is a vertical section through a loDgitudiDal
edge beam o~ a coDcrete slab 6imilar to Figure 7;
~ ig. 12 i6 a vertical ~ectioD througb a loDgitudiDal
edge beam of ~ coDcrete 6~ab aDd the adjacent ~loor area
~imilar to Figure 7 whicn floor ~rea coDtaiDs light weight
insert~;
Fig. 1~ i6 a vertical tran~verse ~ectio~ 6imilar to
~igure 3 ~howing aD additional central loDgitudiDal beam;
~' ~o. ~Dd
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1~7~i865
1 ~ig. 14 is a vertical transver~e ~ectfoD ~f ~ coDcrete
¦ floor 61ab slmilar to Figure 9 ~b~wiDg ~ ~odified form of
lateral ~iffener of tbe co~crete 61ab.
ID Figures 1 to 4 of the accompan~ing drawings, there i~
~howD a coDcrete floor ~lab ~or a traD~portable buildiDg,
whicb compriEes a rectan~ular 1~or area 10 having OD its
underside iDtegrally formed longitudiDal edge beams 12 aDd
lateral edge beams 14. Typically, the edge beams ~ould have
a deptb bet~eeD 250 aDd 550 mm, altbough a depth of about
10. 400 mm is preferred. Furtber, tbe ~loor bas o~ its underside
a plurality of ~Dtegral lateral ~tiifeDers 16 exteDdi~g
between and parallel to tbe loD~itudiDal edge beams 12. The
edge beams 12 and 14 are deeper in sectioD thaD the ~tiffeners
16.
~s caD be ~een iD Figure 4 the loDgitudiDal edge beams
. 12 contain a plurallty of loDgitudinal straDds 18 extendiDg
the entire length of tbe edge beams 12. These straDds 18
will be described iD detail hereinafter but it should be
Doted thht tbe ceDtral straDd 18 ~een in ~igure 4 is curved
20. upwardly. If tbe straDds 18 were distributed evenly i~ the
loDgitudinal edge beams 12 tbeir ceDtre of effort wou~d be
below tbe effective centroid of tbe coDcrete. Tbis would
result in tbe centre of tbe ~lab tendiDg to beDd up~ards. By
curviDg a ~trand 18 up~ardly the up~ard boWiDg teDdeDCy 9i
tbe remaiD~ Dg ~traDdS i6 reduced or preferably neutrali~ed.
~lternatively, ~ore of the ~trands 18 could be located
~d~acent the upper ~urface of tbe 61~b ~o tbat tbe total
CeDtre o~ ef~ort ~o~Dcide~ ~lth tbe e~fective centroid of
I the edge o~ tbe 61-b. B~ 60 arr~Dglng tbe 6traDds 18 iD the
. beams 12, tbe load from tbe strh~ds 18 ~ distributed to avoid
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or mi~imi6e ~tatlc de~ection o~ tbe ~lab. -
In Figure6 ~ ~Dd ~ lt caD be 6eeD $hat e~cb corDer of
the 61ab contaiDs a rectangular iDset baviDg a rigbt ~Dg~ed
rol~ed ~teel ~ectioD 24 ~ounted therein. The 6ectioD~ 24
provide aDcborage for ~teel straDds ~D the edge beams 12 aDd
14. Tbe ~ections 24 transfer load from the ~trands iDto tbe
coDcrete of the slab. As CaD be 6een in Figure ~, the corDers
o~ the 61 ab are thic~eDed to accept the local ~tre~ses aDd to
spread tbe load. Tbe corDer between tbe two sides of eacb
10. 6ection 24 is radiused to reduce the tendency o~ the sectioDs
24 to crack t~e concrete by a wedgin~ action. ~o~ever, other
profiles could be adopted for tbe COrDerS o~ tbe section 24 to
reduce the tendency to crack tbe coDcrete. ~or ex~mple, the
corners could be cbam~ered.
The sectioD 24 could be replaced by a plurality o~ sep-
arate plates. ~or example, there could be a separate plate
for eacb strand end or a respective plate for each ed~e beam 12
and 14.
As caD be eeD iD ~igures 5 and 6 aDd Figure 7, eacb
20. 1on~itudiDal edge bea~ 12 contains six post-teDsioned strands
~8 aDchored to a ~ection 24, aDd located 1D upper and ~ower
groups of three. Further, as can be seen in Figures 5 aDd 6
aDd Figure 8 each lateral edge be~m 14 coDtains two post-
tensioned ~traDd6 28 mounted vertically one above tbe other.
It 6bould be under~tood that tbe Dumber of straDd~ used ~rom
~lab to ~lab caD be ~aried ~idely to ~uit tbe reQuiremeDt6 o~
each particular 61ab.
3 Tbe ~tr~nd6 28 are al60 anchored ~D tbe ~ection6 24.
Furtber, the corner sectloDc ~Dd eacb edge beam 12 and 14
~- CODtaiD deformed bar6 3~. ~be de~ormed bar6 ~ 1D the edge
7.
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beams 12 aDd 19 sssist ln correctly locatiD`g ~ransver~e
ligameDt~ 32 wbicb wrap around tbe ~traDd6 18 and 28. al60,
these de~ormed bar~ 30 extend along tbe edge beams 12 and
14 for their eDtire lengtb and spread tbe teDdeDcy o~ tbe
~ab to crack aloDg tbe entire beam length ratber tban at a
siDgle point. The traDsverse ligaments 32 pre~eDt ~bear ~r
transver~e cr'ackiDg, ~upport pre-teDsioDed ~trands duriDg
coDcrete pouriDg wben pre-tensioned ~traDds are u6ed, and
accept burstiDg stress adjacent tbe eDds of t~e straDds.
~0. ~urther, each corner contaiDs bars 30 witb boGked eDds
to reinforce thi 6 area.
Still further, as can be seen iD ~igures 7 aDd 8 the
~ floor area 10 of tbe slab coD*aiDs a mesh rein~orcement 32
which may be turned downwardly at its edges to exteDd iDto
tbe beams 12 aDd 14. Preferably, the floor area 10 is only
sufficiently tbick to provide sufficieDt streDgth aDd to
cover tbe mesh reinforcement to prevent corrosioD tbereof.
~his, of cour~e, reduces the overall mass of the slab to a
minimum. Typically, tbe geDeral ~loor area 10 betweeD the
20. edge beams and 6tiffeDers is betweeD 25 mm aDd 75 ~ tbick,
more preferably 40 ~m to 60 mm, and most preferably about
50 mm thick. The lateral ~tiffeners 16 are reiDforced by
- deformed or plain bars 36 as sbown iD Figure 9. As sbo~D
in Figure 7, the bar~ 36 may be boo~ed at tbeir eDds. Tbe
bars 36 1D *he illustrated embodiment are located ~D upper
d lower groups oi two. ~s can be ~eeD iD rigure 9, tbe
upper group is ~ithin tbe ~oor ~rea 1~ while the lower group
I is adjaceDt tbe lo~er end6 ~f tbe lateral 6tii'fener6 16.
~urtber, tbe ~ar~ 36 ~ay ~ave tra~sver~e l~ga~ents 38
~0. to ~ccept sbear ~tresse6.
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ID Fi~ure 10, the outer ~ide of a loDgitu~i~al edge
beam 12 1~, as 6bown, Sormed aloDg lts leDgtb ~ith ~ recess
37 which is rectangular ln 6ectioD. The recess 37 is ~rran~ed
to receive tbe louer eDd of aD outside ~all 42 which rests CD
the base of the recess 41. Tbe proviEioD of the recess 37
assi6ts in weather proofing tbe 6tructure.
ID Figure 11 tbere is showD a'longitudiDal edge beam 12
similar to that sh~wn iD Figure 7 but iD this case tbe edge
beam 12 contains & lig~t weigbt insert 41 to reduce weigbt.
10. The iDsert 41 may be formed of i'oamed plastics material such
as foamed polystyreDe. Furtber, it may exteDd coDtiDuously
arou~d the edge beams 12 aDd 14 oi tbe coDcrete slab described
above.
~ n Figure 12 t~ere is ~howD a concrete slab baving a
floor area 10 coDtaiDing a plurality of spaced light ~eight
iDSerts 39. Tbe ligbt weigbt inserts 39 may be fGrDed of a
foamed plastics msteria~ suc~ as foamed polystyreDe. Furtber,
t~e concrete floor area 10 may be-~ormed of fibre ~eiDforced
concrete ~0.
20. Tbus, the preseDt iDveDtioD comprebeDds the use of a
fibre reiDforced floor area 10 as aD alterDative to t~e mesh
reinforced ~l~or area described above.
Figure 13 is a view ~imilar to Figure 3 aDd ~bo~s aD
~dditioDal inter~ediate longitudiDal beam 44 ~hich caD be
uEed to coDfer ~dditional 6trength OD tbe fl~or area.
~igure 14 i6 a view ~imil~r to Figure 9 aDd ~hows a
lateral sti~feDer 16 coDtalDing ~ pre- or post-te~sioDed
6traDd 43.- ~me or all ~f the later~l ~tiffeDer~ 16 may
cont~lD the 6traDd ~3. Furtber, ~ bar ~6 may be used to
3~. accept tocal bur~ting stresse~.
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1~7~:i86S
j ~wrver, the ~e of intermediate tension~d b~ams ~eDds to
¦ $ncroa~e tbe oYerall ~eight Df the ~l~b.
i Tbe po~t-ten~ioned ~tranas 18 and 2B ~re, a6 sh3wn, ~ounted
in conduit~ formed of, for example, po~yvinyl chloride.
~o reduce corrosion and improve performance ~ub6eguent to
~nufacture, grout may be pumped into the conduit. m e
amount of ten~ion applied to the str2nds depends on the
number of ~tr~ su~ed and the ~ize of the ~lab.
~urther, thicker 6trands are able to accept Sreater ~mounts
of tension per ~trand. Basically, the important factor to
~e considered in the agregate amount of tension in all of
the 6trand~ in a beam. Then, it i8 possible to b2ve a large
number of thin 6trands with a lesser amount of tension or a
small number of thick ~trands with a greater amount of
tension. Thu8, in the preferred embodiment, the total tension
applied along the edge beam in the breadthwise direction
~ontaining two.6trands would typically be in excess of
150 kilonewtons, more preferably 300 kilonewtons, and 400
kilonewtons, ~ore preferably 900 kilonewtons, in the
lengthwi~e direction where there are 6 strands.
In the illustrated embodiment, the configuration shown wou~d
be particularly suitable for a slab having dimension6 of the
order of 13.2 metres by 4.2. metres. S~ch a Elab would
typically weigh about 10 tons, which means that the floor
area of the sl b would have an average area of approximat~ y
5.5 eguare metres per ton of slab wei~ht. Generally, it i~
anticipated that m2ssive ~labs ma~ufactured in accordance
with the invention will have average area to weight ratios
falling within the range 4.2 m /ton to lOm /ton, more
preferably 4.8m2/ton to Bm /ton. Slabs baving thi~ area to
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~e ~eight r~t~o w~ul~ 9enerally h~ve tot~l ~urfacc ~ro~s r~Dg~ng
fro~ 34m2 to 7Dm2,
Al~o, it ls preferred ~n the prcscnt invention to n~e a high
~trength concrete h~ving, for example, ~ ~trength of 30-45
.p.a., and h~ving a high cement content. It is found that
a ~lab made from ~uch concrete i6 w~terproof without the need
to u~e additives or the l$ke.
Ihe con~rete ~lab of the present ~nvention i6, upon arrival
at it6 destination, mounted on low blocks or compacted 80il
~nd concrete may be poured around ana under the perimeter.
It then becomes the permanent floor 61ab of the building
unted on it.
Modifications and variations ~uch as would be apparent to a
skilled addressee are deemed within the sçope of the present
inventi~n. For example, it is envisa~ed that the invention
i6 applicable to slab 6hapes other than s~uare or rectangular,
especially if the reinforcing means in the edge beams are
interconnected to provide a "wrap r~und~ tensioning effect
on compressed thick concrete which strengthens the slab.
Further, the tensioned strands would nor~ally be~formed of
steel but it is envisaged that they could alternatively
~e for~ed of pultruded rods of glass reinforced polyester.
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