U.S. patent application number 12/359371 was filed with the patent office on 2009-06-18 for method of making monolithic concrete structures.
Invention is credited to OMAR ABDUL JAZZAR.
Application Number | 20090151298 12/359371 |
Document ID | / |
Family ID | 39081968 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090151298 |
Kind Code |
A1 |
JAZZAR; OMAR ABDUL |
June 18, 2009 |
Method of Making Monolithic Concrete Structures
Abstract
A method of making a monolithic portion of a concrete building
from a combination of pre-cast and cast-in-situ elements
distributes moments and shear loads by using flanged pre-cast
columns for support. In addition, a precast `waffle` element is
used to reduce the overall weight of the slab being formed. In
preferred versions of this method support arms are provided that
link formwork to an anchor cast into a pre-cast column and from the
anchor to a load bearing point on a lower, pre-cured slab.
Inventors: |
JAZZAR; OMAR ABDUL; (JEDDAH,
SA) |
Correspondence
Address: |
DAVID KIEWIT
5901 THIRD ST SOUTH
ST PETERSBURG
FL
33705
US
|
Family ID: |
39081968 |
Appl. No.: |
12/359371 |
Filed: |
January 26, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EG2006/000032 |
Aug 24, 2006 |
|
|
|
12359371 |
|
|
|
|
Current U.S.
Class: |
52/745.05 |
Current CPC
Class: |
E04B 1/34823 20130101;
E04B 1/164 20130101; E04C 3/34 20130101; E04B 5/43 20130101 |
Class at
Publication: |
52/745.05 |
International
Class: |
E04B 1/00 20060101
E04B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 16, 2006 |
EG |
PCT/EG2006/000032 |
Claims
1) A method of making a monolithic reinforced concrete portion of a
building comprising an upper slab portion having a selected
thickness extending between a top surface at a selected top height
to a bottom surface at a selected bottom height, the slab portion
connected to four columns defining a rectangular bay, the method
comprising the steps of: a) providing the four precast reinforced
columns respectively erected at respective corners of the
rectangular bay, each of the columns comprising a respective
vertically extensive portion and a respective horizontally
extensive rectangular reinforced rigid flange portion having rebar
protruding from each of its four edges, wherein each of the flange
members has a top surface at the selected top height, the columns
oriented so that each flange portion has two edges parallel to and
facing respective edges of two other of the flange portions so as
to define four border areas, each of which extends between a
respective pair of the flange portions; b) placing a first
temporary support within the rectangular bay so that a top of the
support is substantially at the selected bottom height; c) placing
a rectangular reinforced precast central slab member on the first
support, the central slab member extending across the bay so as to
abut all four of the flange members, the central slab member having
a thickness over most of its area that is less than the thickness
of the upper slab portion, the central slab member having rebar
protruding outward from each of its edges; d) supporting respective
forms beneath each of the border areas; e) pouring concrete over
the forms and the central slab member to form the upper slab
portion; f) waiting for the concrete to harden; and g) removing the
supports.
2) The method of claim 1 wherein each of the flange portions
comprises four rabbeted edge portions, each of which comprises a
respective lower portion extending further away from the associated
column portion than does a respective upper portion, wherein both
the upper and lower portions have rebar extending outwardly
therefrom.
3) The method of claim 1 wherein the central slab comprises four
rabbeted edge portions, each of which comprises a respective upper
portion extending to a respective edge of the central slab and a
respective lower portion that does not extend to the respective
edge, wherein both the upper and lower portions have rebar
extending outwardly therefrom.
4) The method of claim 1 wherein: each of the flange portions
comprises four rabbeted edge portions, each of which comprises a
respective lower portion extending further away from the associated
column portion than does a respective upper portion, and wherein
both the upper and lower portions have rebar extending outwardly
therefrom except in four flange corner regions; each of the central
slab portions comprises four rabbeted edge portions, each of which
comprises a respective upper portion extending to a respective edge
of the central slab and a respective lower portion that does not
extend to the respective edge, wherein both the upper and lower
portions have rebar extending outwardly therefrom except in four
central slab corner regions; and wherein the dimensions of the
flange portions and central slab are selected so that when the
central slab is placed on the first temporary support, each of the
four central slab corner regions rests on top of a respective
flange portion corner region.
5) The method of claim 1 comprising an additional step, carried out
before the concrete is poured, of placing additional rebar in each
of the border areas, the additional rebar running parallel to a
nearest central slab edge.
6) The method of claim 1 wherein each of the columns comprises a
respective anchor disposed in the vertically extensive portion
thereof, and wherein the step of supporting a respective form plate
beneath each of the border areas comprises connecting a respective
first support arm between the respective form plate and the anchor
disposed in a respective one of the pair of columns defining the
respective border area; and connecting a respective second support
arm between each of the respective anchors and a cured bottom
slab.
7) The method of claim 1 wherein the central slab comprises two
mutually perpendicular sets of rebar running between respective
parallel edges thereof, the slab further comprising a plurality of
low density elements.
8) A method of making a monolithic reinforced concrete portion of a
building comprising an upper slab supported by a plurality of
columns extending above a bottom slab, the method comprising the
steps of: a) providing the plurality of precast reinforced columns
comprising respective vertically extensive portions and respective
horizontally extensive rigid flange portions disposed at a selected
slab height, wherein each vertically extensive portion comprises a
respective anchor for connecting a support arm to the column; b)
erecting the columns to extend from a lower slab to at least the
height of the upper slab; c) placing formwork extending between at
least two of the columns and supporting the formwork by a
combination of at least two first and at least two second support
arms, wherein each of the first support arms connects a respective
portion of the formwork to a respective anchor and wherein each
second support arm connects the respective anchor to a respective
load bearing point on the bottom slab; d) pouring concrete onto the
formwork and allowing it to harden; and e) removing the support
arms and the formwork.
9) The method of claim 8 wherein each anchor comprises a respective
metal member cast into a respective column.
10) The method of claim 8 wherein each support arm is adjustable in
length.
11) A method of making a monolithic reinforced concrete portion of
a building comprising a slab supported by a plurality of columns
comprising at least four columns erected at the four corners of a
rectangular bay, the method comprising the steps of: a) providing a
rectangular pre-cast slab member comprising a plurality of
reinforced beam portions extending parallel to each of the edges of
the slab member and an array of low-density regions disposed
intermediate the beam portions, the slab member comprising rebar
extending outward from each of the beam portions along each of the
four edges of the slab member; b) supporting the slab member in
abutting contact with each of the columns; and c) pouring concrete
to join the slab member to the columns.
12) The method of claim 11 wherein the low density regions comprise
polymeric foam blocks having protrusions extending outward from
faces thereof.
13) The method of claim 11 wherein each of the columns comprises a
laterally extensive flange portion having a rabbeted edge in which
an upper portion of the flange portion is stepped back from the
edge; wherein the slab member comprises a rabbeted edge in which a
lower portion of the slab member is stepped back from the edge and
wherein the step of supporting the slab member in abutting contract
comprises placing each of four corner portions of the slab member
on respective corner portions of each of the flange portions.
14) The method of claim 11 wherein selected portions of the slab
member have a thickness equal to the thickness of the slab and
other selected portions of the slab member have a thickness
substantially equal to one half of the slab thickness.
Description
RELATION TO OTHER APPLICATIONS
[0001] This application is a continuation-in-part of the inventor's
PCT/EG2006/000032, filed on Aug. 24, 2006 and designating the
United States.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to concrete building units that may
comprise both pre-cast and cast-in-situ portions to provide a
continuous cementitious structure that distributes loads and
moments so that less concrete is needed.
[0004] 2. Background Information
[0005] In U.S. Pat. No. 7,121,061, the inventor teaches a method
for making a monolithic reinforced concrete portion of a building
by first erecting flanged wall members in a facing relationship,
where at least one flange on each wall member preferably extends
horizontally toward a facing wall member by about 10-25% of the
intramural spacing. A slab extending across the intramural spacing
is either cast in situ or formed by grouting a precast slab element
into place. An advantage of this method is that when a complete
room is defined by the wall elements, the method distributes
moments and shear in two dimensions and thereby allows for the use
of lighter, thinner structural elements. A disadvantage of this
method is that its reliance on laterally extensive prefabricated
wall members restricts its use to structures, such as apartment
dwellings, that have relatively small openings in those wall
modules, and precludes its use for structures, such as garages,
warehouses and industrial buildings, that commonly provide
relatively large open spaces by using spaced apart columns to
support a ceiling or roof.
[0006] In DE 2,251,613, Schmidt teaches a method of fabricating a
multi-storey cementitious structure in which spaced-apart columns
support the above-grade levels. Schmidt's columns are
pre-fabricated with flanges extending laterally by nearly one half
of the inter-column spacing. A row of such columns is erected and
the flanges on adjacent columns are grouted together to define a
horizontal beam. Pre-fabricated concrete planks are then laid
between two parallel beams and the planks are grouted together and
to the beams so as to form a monolithic structure. A disadvantage
of Schmidt's method is that the load imposed by the concrete planks
is distributed one dimensionally, rather than in both lateral
dimensions. This requires the beams and columns to be heavier and
stronger than would be the case if the loads and moments were
distributed in two dimensions.
[0007] In U.S. Pat. No. 1,516,074 Borg teaches a method of making a
monolithic concrete structure in which a plurality of slabs is
supported by another plurality of columns. Borg does not teach
providing two dimensional support of horizontally extensive
portions of his structure while the structure is being grouted
together.
BRIEF SUMMARY OF THE INVENTION
[0008] One aspect of the invention is that it provides a method of
making a monolithic reinforced concrete upper slab portion of a
building supported by four or more precast columns. The columns are
generally erected above a lower slab to define one or more
generally rectangular bays having a respective column at each of
its corners. Moreover, each of the precast columns has a reinforced
rigid flange portion extending out horizontally at the selected
height from the upper slab. Each flange portion, which is
preferably square in a plan view, has rebar cast into it and
extending outward from portions of all four of its edges. The
columns are oriented so that each flange portion has two edges
parallel to and facing respective edges of the flange portions of
two other columns so as to define four rectangular border areas,
each of which extends between a respective pair of the flange
portions. A temporary support is placed in the middle of the bay
defined by a set of four columns and a rectangular precast central
slab preferably having rebar extending outward from all four edges
is placed on it. The dimensions of the central slab are chosen so
that the slab covers most of the bay and abuts, or slightly
overlaps, all four border areas and the respective corner portions
of all four associated columns. Formwork supported from the lower
slab is placed beneath the border areas and concrete is poured to
form the desired monolithic slab portion comprising the central
slab and all four flange portions. This system distributes the
loads and moments to all four sides, rather than only two sides,
thus allowing for thinner slabs, which reduces weight, materials
costs and labor.
[0009] In a preferred embodiment of the method, each of the precast
columns comprises an anchor that is preferably a metal member cast
into the column at a height about half way between the lower and
upper slabs. When columns of this sort are provided, the formwork
deployed beneath the border areas may be supported during casting
by means of support arms connected to these anchors. In a preferred
embodiment, each anchor is directly connected to two support arms,
one of which extends from the anchor outward and upward to the
formwork and the other of which extends from the anchor outward and
downward to a load bearing point on the lower slab.
[0010] Another aspect of the invention is that it provides a method
of using a relatively low weight slab member for making a
monolithic reinforced concrete portion of a building comprising a
monolithic slab supported by a plurality of columns. These columns
are preferably erected at the four corners of one or more
rectangular bays. The low weight slab or slabs are then placed atop
the columns and are cemented thereto. The low weight slab members
comprise a plurality of reinforced beam portions extending parallel
to each of the edges of the slab member and an array of low-density
regions disposed intermediate the beam portions. Rebar preferably
extends along each reinforced beam portion and protrudes outwardly
from each end thereof.
[0011] In a preferred embodiment, the slab member is formed by
setting the rebar in position in a mold that defines the beam
portions, placing blocks of polymeric foam in the regions between
the rows of rebar and then casting the slab member. In particularly
preferred cases, the weight is further reduced by providing that
much of the precast slab member is thinner than the final slab.
This minimizes the weight of precast pieces that need to be lifted
and lowered into position and allows the builder to bring the
entire slab up to a final specified thickness by pouring additional
concrete on top of the pre-cast slab member.
[0012] In a particular preferred embodiment, the slab member
comprises stepped or rabbeted edges in which an upper portion of
the edge region extends all the way to the edge of the slab member
and the lower portion of the edge region is stepped back therefrom.
When used with a column having a complementary rabbeted flange in
which a lower portion protrudes farther than an upper one, each
corner of the slab can be placed in abutting contact with a
respective flange prior to cementing the slab member to the
column.
[0013] Although it is believed that the foregoing rather broad
summary description may be of use to one who is skilled in the art
and who wishes to learn how to practice the invention, it will be
recognized that the foregoing recital is not intended to list all
of the features and advantages. Those skilled in the art will
appreciate that they may readily use both the underlying ideas and
the specific embodiments disclosed in the following Detailed
Description as a basis for designing other arrangements for
carrying out the same purposes of the present invention and that
such equivalent constructions are within the spirit and scope of
the invention in its broadest form. Moreover, it may be noted that
different embodiments of the invention may provide various
combinations of the recited features and advantages of the
invention, and that less than all of the recited features and
advantages may be provided by some embodiments.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0014] FIG. 1 is a schematic perspective view of an intermediate
step in forming a slab.
[0015] FIG. 2 is a cross-sectional view of an upper portion of a
flanged column, the section taken as indicated by the arrow 2-2 in
FIG. 1.
[0016] FIG. 3 is a detail view, as indicated by the phantom circle
3 in FIG. 1, the view showing a corner of a column flange disposed
beneath a corner of a central slab member.
[0017] FIG. 4 is a plan view of a preferred central slab.
[0018] FIG. 5a is a cross section of a central slab having raised
beam sections, the section taken as indicated by the arrow
5a,b-5a,b in FIG. 4.
[0019] FIG. 5b is a cross section of a preferred central slab
having some rebar held in place with stirrups, the section taken as
indicated by the double-headed arrow 5a,b-5a,b in FIG. 4.
[0020] FIG. 6a is another cross section of the slab of FIG. 5a, the
section taken as indicated by the arrow 6a,b-6a,b in FIG. 4.
[0021] FIG. 6b is another cross section of the preferred central
slab, the section taken as indicated by the arrow 6a,b-6a,b in FIG.
4.
[0022] FIG. 7 is a sectional view showing temporary support arms
used to support formwork used in casting a border area, the section
taken as indicated by the arrow 7-7 in FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0023] In studying this Detailed Description, the reader may be
aided by noting the definitions of certain words and phrases used
throughout this patent document. Wherever those definitions are
provided, those of ordinary skill in the art should understand that
in many, if not most instances, such definitions apply to both
preceding and following uses of such defined words and phrases. At
the outset of this Description, one may note that the terms
"include" and "comprise," as well as derivatives thereof, mean
inclusion without limitation; the term "or," is inclusive, meaning
and/or. The term "bay", as used herein, stands for a rectangular
horizontal division of a structure, and in particular stands for a
region defined by a rectangular grid that may have a column at each
corner thereof or that may have columns at two corners and a wall
portion along one side. The term "rebar" is used herein to denote
elongated reinforcing members of any sort and includes, but is not
limited to, steel reinforcing bars.
[0024] Turning now to FIG. 1, one finds a schematic depiction of an
intermediate step in a process of forming a slab 10 by joining a
plurality of flange portions 12 of respective columns 14 with a
central precast slab portion 16 and by casting border areas 18,
which extend outward from the bay 20, in situ. Although the drawing
depicts only a single bay 20, the reader will understand that the
process herein described is applicable to a multi-bay arrangement.
Moreover, although the depicted single bay has a column at each
corner, the reader should recognize that flanged wall members, as
described by the inventor in his U.S. Pat. No. 7,121,061 can be
substituted for pairs of the depicted columns. The disclosure of
U.S. Pat. No. 7,121,061 is fully incorporated herein by
reference.
[0025] In a preferred configuration, such as that shown in FIG. 2,
each column 14 comprises both a vertically extensive portion 22 and
a flanged portion 12 that preferably comprises a stepped or
rabbeted edge region 24 in which a lower portion 26 of the edge
region extends further outward from the vertically extensive
portion 22 than does an upper portion 28. This rabbeted edge
arrangement is similar to that used on wall members described in
the inventor's U.S. Pat. No. 7,121,061, and has the same preferred
height ratios, set-back distances and protrusion lengths for rebar
29. The rabbeted arrangement aids in transferring shear loads from
a supported portion of the slab to the rigid flange, and thence to
the vertically extensive portion of all of the columns and to
neighboring bays. In a particular preferred embodiment the lower
portion of the rabbet extends ten to twenty centimeters outward
beyond the upper portion of the rabbet. In order to provide a
desirable overlap arrangement with a central slab member 16, rebar
does not protrude from the corners 30 of the flange portions.
[0026] Although the columns 14 are depicted in the drawing as
having a flat top surface, which accords with a process of making a
single storey above grade, the reader should realize that many
other arrangements are possible and that, more generally, the top
of each column may comprise attachment means for mounting the base
of another column used to support a yet higher storey in the
structure.
[0027] The preferred central slab 16 has a complementary rabbeted
edge region in which an upper portion of the edge region 32 extends
further outward than does a lower portion 34. This allows each
corner 35 of the slab member 16 to rest upon a respective corner of
a column flange 12, as depicted in FIG. 3. As described above with
respect to the flange portions, although the central slab member
preferably has rebar extending outward from all its edges, there is
no rebar extending outward from the corner portions that overlap
with the flange portions.
[0028] Turning now to FIG. 4, one finds a plan view of a preferred
central slab member, which is configured as a "waffle". The
preferred central slab member comprises a rim portion 36 having the
rabbet edge features described above. In addition, the slab 16
comprises a grid of reinforced beam portions 38 running parallel to
the edges of the slab 16. The upper portion of the beam portions 38
may have rebar cast into them, as depicted in FIGS. 5a and 6a.
Preferably, the reinforced beam portions comprise rebar cast into
lower portions of the beam and other rebar held on top of the beam
portions by means of stirrups 39. The rebar retained in stirrups is
preferably cast into the center section during a single concrete
pour that tops off the waffle section and forms the border area
portions of the slab. Rebar preferably protrudes through and
outward from the ends of these beam portions as depicted in FIGS.
5a,b and 6a,b. The areas between the beam portions are preferably
only about half the maximum thickness of the central slab member
16, and may be filled, at least partially, with foamed plastic
blocks 40 or other lightweight items.
[0029] In a preferred process, the central slab 16 is pre-cast
using foamed plastic blocks 40 having outwardly protruding ears or
lugs 42. During this casting operation, the blocks 40 are held in
position by the mold (not shown). Subsequently, when concrete is
cast on top of the foam, as will be hereinafter described, the lugs
42 prevent the heavy concrete above the blocks from pushing the
blocks out through the bottom of the precast slab 16. The reader
will recognize that other means of locking the low density blocks
into the concrete may also be employed and that these include,
without limitation, providing a recessed region in the foam and
inserting rebar through the foam and into adjacent areas prior to
casting.
[0030] In a preferred process the columns 14 and wall members (not
shown) are erected on a hardened bottom slab 44 or are supported
above a bottom slab by being attached to another column or wall at
a lower level in the structure--i.e., a column or wall associated
with a building storey below the bottom slab. Free-standing
temporary supports 46 are then placed in the central portion of
each bay and respective central slab members are placed onto each
one of them. As described above, in preferred arrangements, corners
of the slabs are supported not only by the temporary support 46,
but also by the corners of respective column flanges, as depicted
in FIG. 3.
[0031] After the central slab members are in place, the preferred
process calls for the erection of formwork 47 in the border areas.
At this point additional rebar 29 may be introduced into the border
areas and preferably fastened to rebar protruding from a slab or
flange by clamping, welding, or by any other known means. In a
preferred process the formwork in the border areas is supported by
a combination of temporary trusses 48 and support arms 50. In this
arrangement a first support arm 50 is fastened between a truss 48
and a respective anchor 52 in a column adjacent to the truss, as
depicted in FIG. 7. Each such column may then be connected to a
load bearing point 54 on the bottom slab 44. This arrangement has
several advantages, not the least of which is that it provides more
open space for movement of people and equipment on the bottom slab
during the process of setting up for the concrete pour.
[0032] The preferred process allows for a single concrete pour to
complete the slab by filling in the forms in the border areas and
by also filling in those portions of the central slabs that have a
reduced thickness.
[0033] Although the present invention has been described with
respect to several preferred embodiments, many modifications and
alterations can be made without departing from the invention.
Accordingly, it is intended that all such modifications and
alterations be considered as within the spirit and scope of the
invention as defined in the attached claims.
* * * * *