U.S. patent application number 10/320462 was filed with the patent office on 2003-07-17 for precast concrete beam element and methods of making and installing same.
Invention is credited to Miller, Philip Glen.
Application Number | 20030131544 10/320462 |
Document ID | / |
Family ID | 24544450 |
Filed Date | 2003-07-17 |
United States Patent
Application |
20030131544 |
Kind Code |
A1 |
Miller, Philip Glen |
July 17, 2003 |
Precast concrete beam element and methods of making and installing
same
Abstract
An improved precast concrete beam element, useful as a
continuous bearing structural foundation member supporting wall and
floor slab loads in soil, has a unique shape and includes a bearing
surface for spreading vertical loads into the soil and a wall
section having a height sufficient to place the bearing surface at
a specified bearing depth in the soil. Optionally, the precast beam
element also includes a formed-in notch to serve as a block ledge
to facilitate weathertight wall installation. By integrating both
the slab form edge and the wall ledge, the beam element eliminates
the need for field forming. The beam element is manufactured
offsite in a mold capable of changing dimension to cast elements
with differing bearing heights and differing wall thicknesses as
soil and loading conditions require. Installation of the beam
element involves simple suspension of the beam element above an
excavated trench such that a gap is formed between the bottom and
sides of the trench and the surfaces of the beam element. As the
beam element is suspended above the trench, a flowable fill
material is poured into the trench to fill the gap. When the
flowable fill material hardens, the beam element is locked into
place, achieving full bearing and lateral stability.
Inventors: |
Miller, Philip Glen; (Lake
Charles, LA) |
Correspondence
Address: |
PATTON BOGGS LLP
2550 M Street, NW
Washington
DC
20037-1350
US
|
Family ID: |
24544450 |
Appl. No.: |
10/320462 |
Filed: |
December 17, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10320462 |
Dec 17, 2002 |
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09634596 |
Aug 8, 2000 |
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6503025 |
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Current U.S.
Class: |
52/169.1 ;
52/294; 52/741.11 |
Current CPC
Class: |
B28B 7/02 20130101; E02D
27/02 20130101 |
Class at
Publication: |
52/169.1 ;
52/294; 52/741.11 |
International
Class: |
E02D 027/00; E02D
001/00; E04B 001/00; E04G 021/00; E04G 023/00 |
Claims
What is claimed is:
1. A precast structural beam element, comprising: (i) a straight
back face; (ii) a top surface; (iii) a bottom surface; (iv) a front
face; the front face having: a first upper surface extending
perpendicularly and downwardly from the top surface and being
parallel to the back face; a second upper surface which slopes
downwardly and inwardly from the first upper surface; a middle
surface which is parallel to the back face and which extends
downwardly from the second upper surface; a first lower surface
which slopes downwardly and outwardly from the middle surface; and
a second lower surface which is parallel to the back face and which
extends downwardly from the first lower surface and perpendicularly
to the bottom surface; and (v) first and second opposite side faces
disposed between the back and front faces and between the top and
bottom surfaces.
2. A beam element according to claim 1, wherein the top surface of
the beam element has a notch formed therein which extends
lengthwise along the top surface and/or the middle surface of the
front face has a dapped surface formed therein.
3. A method of making the beam element of claim 1, comprising the
steps of: (1) providing a mold comprising: (a) a longitudinally
movable lateral side rail having an inner wall for forming the top
surface of the beam element; (b) an opposite fixed lateral side
rail having an inner wall for forming the bottom surface of the
beam element; (c) a first longitudinal side rail disposed between
the movable and fixed lateral side rails and having an inner wall
for forming the first side face of the beam element; (d) an
opposite second longitudinal side rail disposed between the movable
and fixed lateral side rails and having an inner wall for forming
the second side face of the beam element; (e) an infill plate
disposed between the inner walls of the lateral and longitudinal
side rails such that an upper face of the infill plate and the
inner walls of the lateral and longitudinal side rails define a
mold cavity, the upper face of the infill plate being disposed to
form the front face of the beam element; and (f) one or more dowel
rods projecting upwardly from the mold cavity; (2) filling the mold
cavity with a flowable fill material; (3) allowing the flowable
fill material to harden to form the beam element; and (4) removing
the beam element from the mold cavity.
4. A method according to claim 3, wherein the inner surface of the
longitudinally movable lateral side rail has a configuration so as
to form a notch which extends lengthwise along the top surface,
and/or the upper face of the infill plate has a configuration so as
to form a dapped surface in the middle surface of the front
face.
5. A method according to claim 3, wherein the flowable fill
material is concrete.
6. A method for installing the beam element of claim I into the
ground, comprising the steps of: (1) providing an excavated trench
having a bottom surface, inner wall surfaces and an open top
surface; (2) suspending the beam element above the trench so that a
bottom gap is formed between the bottom face of the beam element
and the bottom surface of the trench and a side gap is formed
between the inner walls of the trench and the front, back and side
faces of the beam element; (3) pouring a flowable fill material
into the trench so as to fill the bottom gap and at least a portion
of the side gap; and (4) causing the poured material to harden.
7. A method according to claim 6, wherein the flowable fill
material is concrete or grout.
8. A method according to claim 6, wherein the top surface of the
beam element has a notch formed therein which extends lengthwise
along the top surface and/or the middle surface of the front face
has a dapped surface formed therein.
9. A method according to claim 6, further comprising after step
(4), the step (5) of installing a second beam element of claim 1 in
accordance with the method of claim 6, the second beam element
being installed adjacent to the beam element installed according to
the method of claim 6.
10. A method for forming a floor slab, comprising the steps of: (1)
installing the beam element of claim 1 in accordance with the
method of claim 6; (2) providing a floor slab-forming location for
forming the floor slab, the location being adjacent to the beam
element such that the back face of the beam element will serve as
an edge form during casting of the floor slab; and (3) casting the
floor slab in said location.
11. A method according to claim 10, wherein, in the beam element
used in step (1), the top surface of the beam element has a notch
formed therein which extends lengthwise along the top surface
and/or the middle surface of the front face has a dapped surface
formed therein.
12. A method of forming a wall slab, comprising the steps: (1)
installing the beam element of claim 1 in accordance with the
method of claim 6; (2) providing a wall slab-forming location for
forming the wall slab, the location being adjacent to the beam
element such that the top face of the beam element will serve as an
edge form during casting of the wall slab; and (3) casting the wall
slab in said location.
13. A method according to claim 12, wherein, in the beam element
used in step (1), the top surface of the beam element has a notch
formed therein which extends lengthwise along the top surface
and/or the middle surface of the front face has a dapped surface
formed therein.
Description
[0001] This is a regular application based on U.S. Provisional
Application No. 60/175,428, which was filed on Jan. 11, 2000.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a precast concrete structural
element and to methods of making and installing same. More
particularly, this invention relates to a precast concrete beam
element for providing continuous footing support in building and
structure foundations and to methods of making the precast element
and installing it in building and structure foundations.
[0003] Several methods for providing continuous beam footing for
wall and floor slab support in building and structural foundations
are known in the art. Three of the most popular methods are
described below.
[0004] One popular method involves excavating a trench, placing
edge forms and reinforcement in the trench, and either partially
casting the beam and then casting the floor slab or simultaneously
casting the beam and floor slab. This method has several
disadvantages. For example, the method requires an excavation that
is open to weather conditions while reinforcement is being placed
in the trench. This often necessitates removal of the reinforcement
after inclement weather has passed in order to remove mud and water
from the excavation and restore bearing capacity prior to casting.
In addition, this method requires field forming of the floor slab
edge and the wall ledge. Thus, the accuracy of the slab edge
forming, the wall ledge forming and the beam shape are each
dependent on the skill of the craftsmen executing the work in the
field. Furthermore, the method uses more concrete that would be
required simply for structural purposes in order to save the cost
of forming a thinner wall thickness that is required structurally.
This increase in sectional area of the concrete necessitates an
increase in the amount of steel reinforcement required under some
building codes. Also, the increase in the bearing width requires
additional unnecessary concrete in the upper section of the
beam.
[0005] A second popular method for providing continuous beam
footing to support wall and floor slab edges involves excavating a
trench, casting the continuous bearing beam in the trench, forming
an upper stem wall section including a support notch for a floor
slab, casting the stem wall section, removing the forms,
backfilling void areas adjacent to the stem wall, and then casting
the floor slab.
[0006] This second method offers some advantages over the first
method discussed above in that, in the second method, the upper
stem wall can be formed to the minimum thickness required for
structural needs, thereby saving substantial concrete material if
the bearing depth is significant. The second method also allows for
a greater difference between finish floor height and the ultimate
exterior grade. However, the second method also has several
disadvantages. For example, it requires an excavation open to
weather conditions as in the first method but in the second method
the excavation is open for an even longer period while the stem
wall section is formed. The second method requires labor-intensive
forming of the stem wall section, often in below grade conditions
which may require continuous dewatering to achieve a structurally
sound installation. The second method further requires subsequent
backfilling and compaction of the void areas adjacent to the stem
wall. Moreover, the second method requires either a notch to
support the floor slab or steel rods through the inner face form to
provide shear dowels into the floor slab. In addition, the accuracy
of the slab edge forming, the slab bearing notch, and the stem wall
section are each dependent on the skill of the craftsmen executing
the work in the field.
[0007] A third popular method for providing continuous beam footing
to support wall and floor slab edges is similar to the second
method discussed above, except that in the third method, the
exterior walls (usually masonry) are extended to the top of the
bearing beam, followed by floor casting. In an advantage over the
second method, the third method eliminates the stem wall forming
step. However, the third method requires an extended period of open
excavation and, typically, the time required for the installation
of the below-grade portion of the exterior wall is even longer than
that required to form the stem wall in the second method.
Furthermore, installation of the below-grade portion of the
exterior wall is labor intensive. In a further disadvantage, the
third method requires backfilling and compaction of the void areas
adjacent to the below-grade portion of the exterior wall. In
addition, accuracy is still dependent upon the skill of the
craftsmen executing the work in the field.
[0008] A primary object of this invention is to provide an improved
concrete beam element which integrates the edge of slab form and
the wall ledge to completely eliminate the need for field
forming.
[0009] Another object of this invention is to provide an improved
concrete beam element which is capable of being cast with dowel
rods projecting above the wet concrete instead of through the
mold.
[0010] A further object of this invention is to provide an improved
method of making a concrete beam element which does not require
field forming.
[0011] A still further object of this invention is to provide an
improved method of making a concrete beam element wherein the
method uses a mold that allows for varying beam heights to
accommodate varying beam depths.
[0012] Another object of this invention is to provide an improved
method of making a concrete beam element wherein the method uses a
mold the depth of which can be easily increased to offer additional
bearing capacity or stem wall thickness as soil and loading
conditions require.
[0013] Yet another object of this invention is to provide an
improved method of installing a concrete beam element wherein the
exposure period of the excavation site to the weather is
significantly less than that required in the prior art methods
discussed hereinabove.
[0014] These objects and others are achieved in the present
invention.
SUMMARY OF THE INVENTION
[0015] The present invention provides an improved precast concrete
beam element for use as a continuous bearing structural foundation
member supporting wall and floor slab loads in soil. The present
invention further provides an improved method of making the
aforementioned precast structural beam element. In addition, the
present invention provides an improved method for installing the
precast concrete beam element of this invention into a building or
structural foundation.
[0016] Specifically, the precast structural beam element of this
invention has:
[0017] (i) a straight back face;
[0018] (ii) a top surface;
[0019] (iii) a bottom surface;
[0020] (iv) a front face; the front face having:
[0021] a first upper surface extending perpendicularly and
downwardly from the top surface and being parallel to the back
face;
[0022] a second upper surface which slopes downwardly and inwardly
from the first upper surface;
[0023] a middle surface which is parallel to the back face and
which extends downwardly from the second upper surface;
[0024] a first lower surface which slopes downwardly and outwardly
from the middle surface; and
[0025] a second lower surface which is parallel to the back face
and which extends downwardly from the first lower surface and
perpendicularly to the bottom surface; and
[0026] (v) first and second opposite side faces disposed between
the back and front faces and between the top and bottom
surfaces.
[0027] Preferably, the beam element of this invention will have a
notch formed therein which extends lengthwise along the top surface
and/or the middle surface of the front face has a dapped surface
formed therein.
[0028] The method of making the beam element involves the steps
of:
[0029] (1) providing a mold containing:
[0030] (a) a longitudinally movable lateral side rail having an
inner wall for forming the top surface of the beam element;
[0031] (b) an opposite fixed lateral side rail having an inner wall
for forming the bottom surface of the beam element;
[0032] (c) a first longitudinal side rail disposed between the
movable and fixed lateral side rails and having an inner wall for
forming the first side face of the beam element;
[0033] (d) an opposite second longitudinal side rail disposed
between the movable and fixed lateral side rails and having an
inner wall for forming the second side face of the beam
element;
[0034] (e) an infill plate disposed between the inner walls of the
lateral and longitudinal side rails such that an upper face of the
infill plate and the inner walls of the lateral and longitudinal
side rails define a mold cavity, the upper face of the infill plate
being disposed to form the front face of the beam element; and
[0035] (f) one or more dowel rods projecting upwardly from the mold
cavity;
[0036] (2) filling the mold cavity with a flowable fill
material;
[0037] (3) allowing the flowable fill material to harden to form
the beam element; and
[0038] (4) removing the beam element from the mold cavity.
[0039] The method of installing the beam element of this invention
involves the steps of:
[0040] (1) providing an excavated trench having a bottom surface,
inner wall surfaces and an open top surface;
[0041] (2) suspending the beam element above the trench so that a
bottom gap is formed between the bottom face of the beam element
and the bottom surface of the trench and a side gap is formed
between the inner walls of the trench and the front, back and side
faces of the beam element;
[0042] (3) pouring a flowable fill material into the trench so as
to fill the bottom gap and at least a portion of the side gap;
and
[0043] (4) causing the poured material to harden.
[0044] The present invention further provides a method for forming
a floor slab, involving the steps of:
[0045] (1) installing the beam element of this invention in
accordance with the method of this invention;
[0046] (2) providing a floor slab-forming location for forming the
floor slab, the location being adjacent to the beam element such
that the back face of the beam element will serve as an edge form
during casting of the floor slab; and
[0047] (3) casting the floor slab in the location.
[0048] In addition, the present invention provides a method of
forming a wall slab, involving the steps of:
[0049] (1) installing the beam element of this invention in
accordance with the method of this invention;
[0050] (2) providing a wall slab-forming location for forming the
wall slab, the location being adjacent to the beam element such
that the top face of the beam element will serve as an edge form
during casting of the wall slab; and
[0051] (3) casting the wall slab in the location.
[0052] The precast concrete beam element of this invention has a
unique shape and includes a bearing surface (defined by the bottom
surface of the beam element) for spreading vertical loads into soil
and a wall section (defined by the back face of the beam element)
having a height sufficient to place the bearing surface at a
specified bearing depth in the soil. Optionally, the precast beam
element also includes a formed-in notch to serve as a block ledge
to facilitate weathertight wall installation. The beam element of
this invention integrates both the slab form edge and the wall
ledge, thereby eliminating the need for field forming.
[0053] The precast concrete beam element of this invention is
manufactured offsite in a mold capable of changing dimension to
cast elements with differing bearing heights. The unique shape of
the beam element allows it to be cast with dowel rods projecting
above the wet concrete instead of through the mold. In addition to
offering adjustable beam height for varying beam depths, the mold
depth can be easily increased to offer additional bearing capacity
or stem wall thickness as soil and loading conditions require.
[0054] The method of installing the precast concrete beam element
of this invention involves the simple suspension of the beam
element above an excavated trench with a gap being formed between
the bottom and sides of the trench and the surfaces of the beam
element. As the beam element is suspended above the trench, a
flowable fill material is poured into the trench to fill the void
areas. When the flowable fill material hardens, the beam element is
locked into place, achieving full bearing and lateral
stability.
[0055] The present invention offers many advantages over the prior
art, as discussed below.
[0056] For example, the beam element of the present invention is
made using an adjustable mold which provides the ability to
manufacture beam elements with varying structural capacities.
[0057] In addition, the particular cross-section of the beam
element of this invention provides structural capacity with minimal
material and weight. Furthermore, such cross-section also allows
for efficient stacking of the beam elements in the storage yard and
facilitates easy handling for loading and trucking.
[0058] Another advantage is that the beam element of this invention
is capable of serving as a stay-in-place form for the slab edge and
the wall ledge.
[0059] Another advantage of the present invention is that the
construction site can be prepared while the beam elements are being
produced offsite. This facilitates rapid installation of the
elements as soon as the site preparation is complete.
[0060] Furthermore, in the present invention, the flowable fill
material is cast as the beam elements are being installed, thereby
greatly reducing the exposure time of the excavation site to
inclement weather.
[0061] No edge forming of the slab, wall ledge or field forming of
the stem wall is required in the method of making the beam element
of the present invention.
[0062] Installation accuracy is assured in the present invention
since the installation workmen can adjust the beam location using
an adjustable hanger. The beam element is grouted and secured into
place before the slab is cast, thereby assuring that the edge will
not vary as field forms tend to do under the pressure of concrete
casting.
[0063] Another advantage offered by the present invention is that
the use of special forms to make the beam elements eliminates
dependency on skilled labor to assure accurate beam and slab edge
dimensions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] FIG. 1 is a schematic illustration of a longitudinal side
view of a mold which can be used to form the beam element of this
invention.
[0065] FIG. 2 is a schematic illustration of a perspective view of
the mold shown in FIG. 1.
[0066] FIG. 3 is a schematic illustration of the mold shown in FIG.
1, wherein the mold is filled with concrete.
[0067] FIG. 4 is a schematic illustration of a beam element of this
invention formed from the mold shown in FIGS. 1-3, wherein the beam
element is being removed from the mold.
[0068] FIG. 5 is a schematic illustration of a stack of the
invention beam elements for storage and shipping.
[0069] FIG. 6 is a schematic illustration of a beam element of the
present invention being suspended over a trench in accordance with
the installation method of this invention.
[0070] FIG. 7 is a schematic illustration of the grouting step of
the installation method of this invention using the beam element
and trench shown in FIG. 6.
[0071] FIG. 8 is a schematic illustration of the slab-pouring step
of the installation method of this invention, using the beam
element, trench and grouting material shown in FIG. 7.
[0072] FIG. 9 is a schematic illustration of the installed beam
element of this invention prior to removal of the suspension
equipment.
DETAILED DESCRIPTION OF THE INVENTION
[0073] The precast concrete beam element of this invention, its
method of manufacture and its method of installation will be
described with reference to FIGS. 1-9 herein.
[0074] The precast concrete beam element of this invention is
manufactured in a mold capable of changing dimension to cast
elements with differing bearing depths and structural capacities.
Such a mold is represented by reference numeral 2 in FIGS. 1-4.
[0075] Mold 2 includes a movable lateral side rail 4, a fixed
lateral side rail 6, and first and second longitudinal side rails
(not shown). Movable lateral side rail 4 has an inner wall 4a, an
upper portion of which preferably contains a notch 4b. Notch 4b is
used to form a notch 36 in the concrete beam element (see FIGS.
4-9). Fixed lateral side rail 6 has an inner wall 6a. A channel 8
is defined between the inner walls 4a, 6a of the lateral side
rails, the inner walls (not shown) of the longitudinal side rails
and the upper face of a support member 10.
[0076] Movable lateral side rail 4 rests on a movable side rail
base member 12 which in turn rests on support member 10. Fixed
lateral side rail 6 also rests on support member 10.
[0077] Side rail base member 12 is longitudinally movable in the
direction shown. In the embodiment shown in FIG. 2, side rail base
member 12 and support member 10 each contain through-holes (not
shown) and are attached to one another at a contact point 14 by
aligning the respective through-holes in the base member and the
support member and then placing screws 16 placed in the
through-holes. In such embodiment, the base member 12 can be moved
by removing the screws and moving the base member to a second
contact point (not shown) located either on support member 10 or on
a subsequent support member (not shown). At the second contact
point, the support member will contain through-holes (not shown),
which are aligned with the through-holes disposed in the side rail
base member. Screws 16 are then placed through the aligned
through-holes, thereby securing the side rail base member 12 to the
support member at a second contact point.
[0078] Mold 2 preferably further includes a number of support
blocks 18 preferably one support block every four feet), preferably
made of wood, which is placed in channel 8. Blocks 18 inturn each
preferably rest on a second support block 20. An infill plate 22
(preferably made of steel), the upper face of which defines the
front face of the beam element to be formed, is placed in channel 8
over support blocks 18. The upper face 22a of plate 22, inner walls
4a, 6a of the lateral rails 4, 6, and the inner walls (not shown)
of the longitudinal side rails define a mold cavity 24. Upper face
22a of plate 22 forms the front face of the beam element to be
formed, the inner wall 4a of side rail 4 forms the top face of the
beam element, the inner wall 6a of side rail 6 forms the bottom
surface of the beam element, and the tipper edge of mold cavity 24
forms the straight back face of the beam element. The inner walls
of the longitudinal side rails (not shown) form the side faces of
the beam element.
[0079] The height of the beam element to be formed can be increased
by moving side rail 4, via side rail base member 12, longitudinally
in the direction shown, as discussed hereinabove.
[0080] Projecting within and vertically upwardly from mold cavity
24 are one or more dowel rods 26. Dowel rod(s) has an upstanding
portion 26a and an embedded portion 26b which is embedded in the
concrete beam element to be formed.
[0081] FIG. 3 shows mold cavity 24 filled with concrete C to effect
casting of the beam element of this invention. An advantage of the
present invention is that the dowel rod(s) 26 is positioned in the
mold cavity when the wet concrete is poured therein. Thus, the
dowel rod portion 26a projects above the wet concrete instead of
through the mold. This allows steel rods to project above the
surface of the formed concrete beam element to dowel into the floor
slab without requiring a penetration of the mold.
[0082] After the concrete C has hardened in mold cavity 24, the
resulting beam element 28 is removed from mold 2. As shown in FIG.
4, the beam element 28 can be removed from the mold by pivoting
lateral side rails 4 and 6 outwardly (in the direction of the
arrows shown in FIG. 2) until the rails rest on rail-stopping
members 30 and 32, respectively, and by pivoting longitudinal side
rails (not shown) in the same manner.
[0083] As can be seen in FIG. 4, dowel rod portion 26a protrudes
upwardly from the formed beam element 28.
[0084] During storage and shipping, a plurality of beam elements 28
can be stacked as shown in FIG. 5, with spacers 34 disposed between
adjacent beam elements.
[0085] The beam element of this invention preferably has the shape
shown in FIGS. 4-9 herein.
[0086] As shown in FIGS. 4-9, beam element 28 includes a straight
back face 28a, a top surface 28b, a bottom surface 28c, a shaped
front face defined by surfaces 28d, 28e, 28f, 28g and 28h, and side
faces 28i. Back face 28a and side faces 28i are designed to extend
vertically relative to the ground G when the beam element is
installed. Top surface 28b is straight except for a notch 36
preferably formed therein which extends lengthwise along top
surface 28b (see FIG. 9). Notch 36 serves as a block ledge during
the casting of the floor slab and can facilitate weathertight wall
installation. Top surface 28b is intended to extend horizontally
relative to the ground G when the beam element is installed. Bottom
surface 28c is also straight and is designed to extend horizontally
relative to the ground G when the beam element is installed.
[0087] Beam element 28 is composed of (i) a first or upper flange
defined by an upper portion of back face 28a, top surface 28b,
front-face surfaces 28d and 28e; and upper portions of side faces
28i; (ii) a middle section defined by a middle portion of back face
28a, front-face surface 28f and dapped surface 38 (see FIG. 9) and
middle portions of the side faces 28i; and (iii) a second or lower
flange defined by a lower portion of back face 28a, front-face
surfaces 28g and 28h, bottom face 28c, and lower portions of side
faces 28i. Surface 28d of the upper flange is straight and parallel
to the back face 28a of the beam element. Surface 28e of the upper
flange slopes inwardly and downwardly from surface 28d toward the
middle of the beam element. Surface 28f is straight and parallel to
back face 28a of the beam element. Surface 28g of the lower flange
extends outwardly and downwardly from surface 28f. Surface 28h of
the lower flange is straight and parallel to back face 28a of the
beam element. Dapped surface 38, which has a Z shape, is used to
align the plurality of beam elements during installation.
[0088] Installation of the beam elements of this invention can be
understood by reference to FIGS. 6-9.
[0089] As shown in FIG. 6, precast beam element 28 is suspended
above an excavated trench 40 having a bottom surface 40a and side
walls 40b. The beam element is suspended above trench 40 in such a
way as to leave a gap or void area 42a between the bottom face of
the beam element and the bottom surface of the trench; and a gap or
void area 42b between the front, back and side faces of the beam
element and the inner walls of trench 40. The particular depth and
width of the trench will vary according to the structural
requirements for individual buildings and foundation
conditions.
[0090] Beam element 28 is suspended by bearing the first or upper
flange (defined by surfaces 28b, 28d and 28e and a portion of back
face 28a) of the beam element on the dapped end (not shown) of a
previously installed beam element (not shown), thereby aligning
beam element 28 with the previous beam element. The second or lower
flange (defined by surfaces 28g, 28h, 28c and a portion of back
face 28a) of beam element 28 is supported by a special adjustable
suspension hanger 44 that is fully adjustable in the directions
shown (i.e., vertically and horizontally) and torsionally. First
and second end members 44a and 44b of the hanger rest on the ground
G as shown in FIG. 6.
[0091] As can be seen in FIG. 7, as beam element 28 is suspended
above trench 40, a flowable fill material 46 (e.g., grout or wet
concrete) is poured into the trench to fill gap 42a and at least a
portion of gap 42b. As used herein, the term "pouring" is intended
to include a pumping operation.
[0092] When material 46 hardens, the beam element 28 is locked into
place, achieving full bearing and lateral stability. To reduce the
required flowable fill volume to the minimum required for
structural support, the remainder of gap 42b can be filled with
inexpensive granular fill 48 (e.g., sand) and backfilled soil 50,
as shown in FIG. 8.
[0093] Since the flowable fill material 46 is capable of
transferring load in a diagonal shear cone, the effective bearing
area can be the fill width of trench 40 if the portion of gap 42a
below the bottom face 28c of beam element 28 is equal to the
portion of gap 42b between the trench inner walls 40b and the
front, back and side surfaces of beam element 28. By increasing the
depth and width of the trench, the bearing area can effectively be
increased without enlarging the beam element. As discussed
hereinabove, the beam element of this invention can also be
expanded in width, stem wall thickness and depth so that a wide
variety of loading and soil conditions can be accommodated.
[0094] After beam element 28 has been secured into place, a floor
slab 52 can be cast, as shown in FIG. 8. During casting of the
slab, the beam element will not vary as field forms tend to do
under the pressure of concrete casting. Thus, beam element 28 can
serve as a stay-in-place edge form during formation of the
cast-in-place floor slab 52.
[0095] As stated previously herein, in preferred embodiments, beam
element 28 further has disposed therein a notch 38 (FIG. 9)
extending along the length of the beam element. Notch 38 can serve
as a block edge to facilitate weathertight installation of a wall
slab 54.
[0096] The precast concrete beam element of this invention can be
made directly at the construction site by using a portable,
ready-mix bulk plant. However, it is preferred to precast the beam
elements at a remote fabrication location dedicated to that purpose
and then transported to the construction site.
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