Note: Descriptions are shown in the official language in which they were submitted.
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Method and apparatus for precast and framed block element construction
David W. Powell
RELATED APPLICATIONS
This application is related to U.S. Provisional Patent Application No.
601417,065
filed October 8, 2002, and claims the benefit of that filing date.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to a building system that consists of pre-cast
structural
building blocks and precast or framed floor, wall and roof blocks, the
combination of
those blocks to create structural elements, and methods of manufacturing,
assembly,
disassembly and reconfiguration of those blocks.
2. Description of Related Art
Various types of construction are known in the prior art including wood framed
buildings, steel framed buildings, and concrete structures.
The majority of structural design decisions that are made in conventional
practice
are driven by cost; there are enormous pressures on structural engineers of
most building
projects to minimize costs while upholding their first duty to ensure the
safety of
structures. These pressures tend to minimize the structure in many buildings.
This
tendency can be unfortunate When a structure is subjected to rare but extreme
loads that
cannot reasonably be incorporated into statistical load guidance provided by
building
codes.
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Accordingly, engineered structures are typically designed to safely resist
code-
specified loads without necessarily providing large reserve capacity beyond
that achieved
by virtue of required safety factors. By building to provide~structural
capacities that are
significantly in excess of those required to resist the minimum loads required
by building
codes, new opportunities are created in the functionality and versatility of
the built
structure.
The design of a structure of conventional construction typically seeks to
concentrate forces to conserve usable floor space, and relies on secondary
lateral systems,
such as diagonal braces or shear walls, to stabilize the structure. Benefits
can be gained
by intentionally distributing structural forces across a wide base that
minimizes stresses
on the supporting surface.
Conventional construction generally consists either cast-in-place construction
with
obstructive and costly formwork, or of interconnected stick or panel framing
that relies on
diagonal bracing or shear walls for lateral stability. Because much of
conventional
construction is inherently unstable until the construction of structural
diaphragms and
lateral systems are complete, structural failures during the relatively brief
construction
period are more common than in completed buildings that stand for years of
service.
The lateral bracing and shoring that is typically required for conventional
construction creates building site obstructions that contribute to many
construction
accidents. Because conventional construction commonly involves the field
assembly of
parts that can be lifted and handled by one or two workers, the construction
of exterior
walls and roofs generally involves a significant amount of labor far above
ground level;
this creates the potential for falling hazards that generate the most lethal
jobsite injuries.
Where conventional construction utilizes large parts, such as with tilt-wall
construction,
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expensive crane time is typically consumed holding those parts in position
while lateral
shoring and bracing members and connections are installed; this is required to
stabilize
the part prior to releasing the hoisting lines. It is desirable to build using
a system of
independently stable modules that eliminate the need for temporary shoring and
bracing,
and that allow crane time to be utilized efficiently.
In the field of concrete buildings or concrete framed structures, the
structural
elements are typically either cast in place on site such as with flat-plate or
beam and slab
type of applications, prefabricated on-site such as with tilt wall
construction, or
prefabricated off-site such as with precast concrete planks, tees, and wall
blocks. Most
significant building structures are built based on a unique design that is the
result of the
work a team of design professionals; the design of a given building is
generally unique to
that project. The design of unique projects under ever-increasing time,
budget, and
liability pressures presents real challenges to design professionals; it also
places an
enormous burden on the builder that must interpret and build a unique and
complex
project from what will inevitably prove to be an imperfect set of drawings and
specifications. It is highly desirable to introduce a building system that
allows design
flexibility while offering vast simplifications in both design and
construction; this can be
accomplished by means of an expanding kit of compatible parts.
The use of on-site casting for concrete cast-in-place structures requires the
expense and delay of field-fabricating the forms for pouring concrete. It is
desirable to
provide concrete structural elements which can be built in stacks or mass-
produced by
other means either on-site or under factory controlled conditions.
Tilt wall construction provides some advantage in pre-casting wall elements,
but
has the disadvantage of requiring the advance construction of large areas of
grade-
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supported slab to serve as a casting surface for the wall blocks. Tilt wall
construction also
requires the use of temporary shoring during the assembly process to hold
walls in place
until additional structural elements are attached to the walls. It is
desirable to provide pre-
cast concrete structural elements that can be assembled into a variety of
structural
elements and finished buildings without the use of temporary shoring.
Concrete building blocks such as cinder blocks are typically provided in
relatively
small units that require labor-intensive mortared assembly to form walls and
structures. It
is desirable to provide larger structural units that can be site cast in
stacks or trucked to a
job site and assembled together into a wide variety of structural forms
without extensive
use of mortar or adhesive.
Once conventional construction is complete, the modification or removal of a
finished building generally involves destructive demolition. It is common
practice in
conventional construction to design for a relatively short building life span,
and to simply
demolish buildings that because of age, location, or poor initial construction
have met the
end of their useful service lives. This practice results in millions of tons
of construction
debris being hauled to landfills every year. It is desirable to build using a
system that is
built of durable but cost-effective construction and which offers ease of
modification or
removal and reuse without the waste of materials and manpower associated with
conventional demolition practices. It is desirable to introduce a building
system that
enables the wholesale recycling and reuse of entire buildings by use of
durably
constructed large-scale building blocks.
This invention provides the unexpected benefit of deliberately using a large
footprint for structural modules. In typical construction, support elements
such as
concrete columns or steel beams have relatively small footprints to maximize
usable floor
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space of a structure. In this invention, blocks and structural modules with
large footprints
are used. The advantages of this approach include the ability to construct a
structural
frame from relatively simple planar elements that can be cast on site or
efficiently
manufactured under controlled conditions and shipped to the site. Much of the
assembly
can be done at ground level. Structural modules assembled in this manner may
be erected
quickly and are stable without temporary shoring. The completed frame may be
disassembled quickly, and components can be reused. There is less load per
area on base
elements, so slab or foundation requirements are relaxed. Some applications
can be
assembled on grade. In many cases, the space inside the structural modules can
be
accessed and used effectively.
BRIEF SUMMARY OF THE INVENTION
The method and apparatus for construction described herein provides a system
of
precast reinforced structural building blocks that may be replicated and
combined with
identical blocks to form a variety of structural elements, and with modified
but similar
and complimentary blocks to form a complete primary structure. The primary
structure
can then be enclosed using manufactured blocks or either precast or framed
construction
to establish perimeter walls and roofs.
In various embodiments of the current invention, precast elements maybe
fabricated in an efficient controlled environment such as through stack
casting to provide
plurality of building elements which maybe configured into a wide variety of
desirable
structures. The elements that can be created by combining modular blocks
include walls,
portions of walls, support columns, roof trusses and completed structural
frames. These
building blocks may be quickly assembled at a construction site and may be
supported on
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a concrete slab, on discreet foundations, and in some cases directly on grade.
By
combining individual blocks or combinations of blocks with other combinations
of
blocks, diverse structural frames and buildings can be quickly designed and
assembled.
By building using large manufactured blocks with simple bolted or interlocking
connections, frames and entire buildings of this construction can also be
modified or
dismantled without demolition.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
These and other objects and advantages of the present invention are set forth
below and further made clear by reference to the drawings, wherein:
FIG. 1A is an elevation view of a single block.
FIG. 1B is an isometric view of the block of FIG. lA.
FIG. 2A is a perspective view of blocks being lifted by a top edge.
FIG. 2B is a perspective view of blocks being lifted by a first edge chord and
assembled
on the ground.
FIG. 3A is a front view of various block configurations
FIG. 3B is a cross section view of a rectangular beam
FIG. 3C is a cross section view of a six sided polygonal beam
FIG. 4 is a front view of a variety of block shapes.
FIG. 5A is a front view of biaxial block connection sleeves
FIG. 5B is a perspective view of biaxial block connection sleeves
FIG. 6 is a perspective view of a portion of the block reinforcement
FIG. 7 is a perspective view showing the alignment and connection of blocks
with biaxial
sleeves.
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FIG. 8A is a detailed perspective view of a portion of a form with a sleeve
receiver
FIG. 8B is a detailed perspective view of a portion of a form with a sleeve
and a sleeve
receiver
FIG. 9 is a front view of typical reinforcement for a block.
FIG. l0A is a perspective view of a reinforcement cage step in a stack casting
sequence
FIG. 10B is a perspective view of a first level form tying step in a stack
casting sequence
FIG. lOC is a perspective view of a first level concrete cast step in a stack
casting
sequence
FIG. lOD is a perspective view of an inverting forms step in a stack casting
sequence
FIG. l0E is a perspective view of a subsequent level preparation step in a
stack casting
sequence
FIG. 11 is a perspective view of several block columns attached to a surface
with
connectors through base sleeves.
FIG. 12 is a perspective view of pairs of blocks fornning "L" shaped elements.
FIG. 13A is a perspective view of several blocks forming a flat wall.
FIG. 13B is a perspective view of several blocks forming a perimeter wall
system of
arbitrary layout
FIG. 14 is a perspective view of several blocks forming a pilastered wall.
FIG. 15 is a perspective view of several blocks forming a ribbed wall.
FIG. 16 is a perspective view of several blocks forming square and rectangular
box
columns.
FIG. 17 is a perspective view of box columns supporting steel floor framing
blocks.
FIG. 18 is a perspective view of a completed primary structural frame with box
columns
supporting roof trusses on discrete cap elements
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FIG. 19 is the frame of FIG. 18 carrying light-gage steel secondary framing
FIG. 20A is a one-story block with cantilever chord extensions at the second
level
FIG. 20B is a two-story block with cantilever chord extensions at the second
level
FIG. 20C is a three-story block with cantilever chord extensions at the second
level
FIG. 20D shows a three-story block with a lateral bay to carry a shed roof and
an omitted
bottom chord for pedestrian passage
FIG. 20E is a two-story block with an omitted bottom chord for pedestrian
passage
FIG. 20F is a three-story block with cantilever chord extensions and a sloping
top chord
for roof block support
FIG. 20G is a one-story block with a sloping top chord
FIG. 20H is a one-story block with a stepped, double-sloping top chord
FIG. 20J is a two-story block with a stepped bottom chord to receive a dropped
floor and
a sloping top chord for roof block support
FIG. 21A is a triangular block
FIG. 21B is a wishbone spacer block for connection of two adjacent blocks into
a module
FIG. 21C is a roof truss block with a segmented arc top chord
FIG. 21D is a bowstring truss block with a steel tie rod
FIG. 21E is a perspective view of a corner cap block
FIG. 21F is a view of the underside of the block shown in 21E
FIG. 22A is an exploded perspective view of a paired roof truss module
FIG. 22B is an asymmetric box column
FIG. 23A is a framed wall block with light gauge metal wall framing
FIG. 23B is an inside view of the wall block shown in FIG. 23A
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FIG. 23C is an exterior view of three varieties of precast wall blocks that
depicts a cast
pattern that emulates stacked stone
FIG. 23D is an inside view three varieties of precast wall blocks
FIG. 23E is hinged wall blocks
FIG. 24A is a view of the interior framework of a framed wall block
FIG. 24B is a view of the framed wall block of FIG. 24A with inner and outer
metal skins
installed
FIG. 25A is a perspective view of an assembled wall block on open box columns
FIG. 25B is a detailed view of a hanger connection.
FIG. 26A is a top view of precast roof blocks
FIG. 26B is an underside view of precast roof blocks
FIG. 27A is a perspective view of steel framing for a framed roof block
FIG. 27B is a perspective view of a framed roof block with metal panels
installed
FIG. 27C is a detail view of a bolted connection clip
FIG. 27D is an underside view of the completed roof block
FIG. 2~ is an assembly of a roof block on an asymmetric column
FIG. 29A is an assembly of two box columns fitted with bolted haunches
carrying floor
support blocks
FIG. 29B is three winged box columns supporting precast floor blocks
FIG. 29C is a top view of two precast floor blocks
FIG. 29D is an underside view of two precast floor blocks
FIG. 30A is an exploded view of a three part precast floor block assembly
FIG. 30B is an underside view of a precast floor block assembly
FIG. 31A is three modules that are used to begin assembly of a structural
shell
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FIG. 31B is three modules with installed floor blocks
FIG. 31C is three modules with installed wall blocks added to the structural
shell
FIG. 31D is a completed structural shell with roof blocks
FIG. 32A is six modules on a slab with an overhang that is used to build a
structural shell
5 FIG. 32B is the addition of suspended access floor blocks and paired roof
truss modules
FIG. 32C is adding the installed wall blocks, clerestory blocks, wall header
blocks, and
sliding door blocks
FIG. 32D is the enclosed structural shell completed by the installation of
roof blocks
FIG. 33A is twelve box columns sitting on a slab to begin assembly of a
structural shell
10 FIG. 33B is a detailed view of bolted haunches
FIG. 33C is a perspective view of box column modules carrying framed floor
blocks
FIG. 33D is a primary frame with solid cap blocks carrying tied bowstring
trusses
FIG. 33E is a near completed structure after installation of precast wall
blocks, metal wall
studs, and metal roof deck
FIG. 34A is an example of a multi level structural shell with slab, box
columns, various
winged box columns of various heights
FIG. 34B is an example of a mufti level structural shell with the addition of
cap blocks,
floor modules and a hinged wall block.
FIG. 35A is an example of walk through box columns on a slab with simple box
columns
at each end
FIG. 35B is the addition of the corner cap elements and cap elements added to
the walk
through box columns and box columns
FIG. 35C is the addition of wall and low roof blocks to the assembled
structure
FIG. 35D is the upper roof consisting of framed roof blocks and clerestory
roof blocks
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DETAILED DESCRIPTION OF EMBODIMENT - Precast and framed construction
blocks
A basic block of one embodiment of the invention is shown in FIG. lA and FIG.
1B which are an elevation and isometric view of a single block. It is from the
geometry
of this most basic block of the building system that LadderBlockTM derives its
name. The
block 10 shown is 5 feet wide, 30 feet tall, and 6 inches thick, with two edge
chords 21
and 22, and three vertical openings 41-43 defined by beam sections 31-34. This
block is
referred to as a three-story block in this discussion. In one example,
reinforced concrete
chord sections of this embodiment are 6" wide by 6" thick, and beam sections
are 12"
deep by 6" thick. The block overall geometry, dimensions, number of openings,
cross-
sectional dimensions and reinforcement may each be adjusted within practical
limits for a
specific application.
The design of this system is intended to allow the rapid replication of
identical
high-quality building blocks to serve as large-scale building elements that
enable rapid
but sturdy construction. The control and assurance of quality construction can
readily be
achieved by the repetitive manufacture of identical parts. Blocks are
generally intended
to be cast flat and then lifted into position. FIG. 2A is a perspective view
of blocks 10
being lifted by a top edge 34, such as by a crane (not shown). Fig 2B is a
perspective
view of blocks 10 being lifted by a first edge chord 21, and then assembled on
the ground
as illustrated by block l0a being attached by a edge chord 22 to the first
edge chord.
Replication of blocks may be accomplished by stack-casting a series of blocks
one
on top of another, or by means of a forming system that allows rapid stripping
and re-
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utilization of forms. Blocks may be site-cast on a previously built concrete
floor slab, or
they may be precast and shipped to the jobsite on flatbed trailers.
Block geometry
The configuration of a block may be modified in several ways, such that a
given block geometry may be manipulated by the design professional as required
for a
specific use. Blocks are planar elements that generally consist of two or more
chords
with monolithically cast rigid joints at chord intersections. Chords may or
may not be
orthogonal to one another, and they may cantilever beyond the shape enclosed
by other
beams and chords as required to provide extensions for the support of
foundation, floor,
or roof elements. Cross-sections of block chords may also be thickened and
more heavily
reinforced where required by structural analysis. In addition, cross-sections
of beams and
chords may be modified in cross-section to be other than rectangular as shown
in FIG.
3B; what is essential to permit stack-casting and stacked shipping is that
elements remain
planar. If cast in separable forms, for example, it is convenient for beam and
chord cross-
sections to incorporate a taper from each side toward the centerline of the
cross-section to
facilitate form stripping, as indicated in the beam cross-section FIG. 3C. The
resulting
six-sided polygon presents new opportunities for the interlock of supported
parts, as
depicted in FIG. 3C. Referring again to FIG. lA and 1B, the geometry in the
example
embodiment provides three openings through the erected block with a horizontal
clearance of 4 feet between parallel chords and a vertical clearance of 8 feet
8 inches
between parallel beam elements. These clear openings are constricted by 4 inch
chamfers
38 at each corner, and are intended to provide the required headroom and
lateral clearance
required for a person to pass through the opening with floor framing supported
by the
beam element below the opening.
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In addition to dimensional variability described above, the base block may be
modified by the introduction of additional and variously spaced beam elements
as
illustrated in FIG. 3A which is a front view of various block configurations
10c-10g. The
beams may be used to stiffen the block or to provide additional lines of
support for
secondary framing where passage through the block is not required. FIG. 3A
illustrates
variability of block height, block width, the number and location of beams in
a block, and
in the beam or chord cross sectional shape.
The beams and chords need not be orthogonal. FIG. 4 is a front view of a
variety
of block shapes. For instance, block 12 includes the addition of sloped
diagonal struts 61.
Struts may be steel assemblies that are designed to bolt to cast-in sleeves,
or they may be
reinforced concrete cast monolithically with the module.
Block 11 illustrates the use of a sloped chords 23 such as may be utilized to
build
a battered wall, to stiffen a block in response to high lateral forces, or to
utilize a block as
a long-span horizontal framing member.
A sloped chord roof truss 13, may be formed by assembling two sloped chord
blocks 11 with optional.diagonal struts 61, or may be cast as a single unit.
Biaxial block connection sleeves
In one embodiment, the block is designed to incorporate a series of cast-in
sleeves
that serve a number of functions. In this embodiment, sleeves are shown as 1
1/z"
diameter steel pipe. Sleeves are intentionally oversized to provide fit-up
tolerance.
Threaded rod connectors that pass through the 1 1/z" diameter sleeves will
typically be in
the 3/a" to 1" diameter range. In this embodiment, pipe sleeve lengths are 6"
through
chord sections and 12" through beam sections, and pairs of sleeves 101 and 102
are
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centered and tack-welded at 90 degrees to one another, as illustrated in FIG.
SA and SB,
to form biaxial modular connection sleeves 100.
These pairs of connection sleeves are positioned at modular locations within
each
chord element, typically centered within the reinforcement 120 as shown in
FIG. 6.
Other sleeves such as vertical sleeves 103 for attachment to a foundation,
attachment of
roofing elements, or attachment of shelving or flooring members are typically
also
included in the block reinforcement.
In this embodiment, the sleeve pairs are asymmetric and may be rotated 90
degrees from the left edge chord 22 to the right edge chord 21 of the block as
shown by
pairs of connection sleeves 105 and 106 in FIG. 7. The result of this rotation
is that a
chord sleeve at any given level will align with its counterpart in a second
identical block,
but it will also align with a sleeve in the 90 degree opposing face of the
other chord of the
second identical block. For instance, block 10i is located between block 10h,
which is
rotated 180 degrees with respect to block 10i, and block 10j which is rotated
270 degrees
with respect to block 10i. By rotating a block in plan, one can therefore
interconnect
identical blocks to form a variety of configurations, as described below. In
other
embodiments, the sleeve pairs are symmetric so that they can be used to form
modules
such as paired trusses or asymmetric columns as discussed below.
In addition to the interconnection of blocks, sleeves may serve a number of
functions both during construction of the block and in the assembled
structure. During
construction of the block, sleeves serve as internal chairs to hold
reinforcing steel in
position. Referring now to FIG. 8A and 8B, which are detailed perspective view
of a
portion of a forming system for this embodiment, form 201 incorporates a
sleeve receiver
120 on its inside face that positions sleeve 100 and provides a simple method
for tying the
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form together during casting. As described below, forms may also incorporate a
spaced
sleeve receiver that serves to position the form for a subsequent, stack-cast
replication of
the block.
Sleeves also provide connection points for stripping and lifting the cast
block, and
5 for connections to and support of secondary framing in the assembled
structure. Sleeves
through beam elements provide opportunities for anchor bolt connections to the
supporting structure, for the connection of intermediate levels of supported
framing, and
for the connection of cap elements or roof framing.
10 Where the structural spacing and interconnection of two identical,
asymmetrical
blocks is desired, as depicted in FIG. 22A and 22B, biaxial connection sleeves
are
oriented to provide consistent sleeve heights at each side of the spacer
block. In cases
such as this the orientation of biaxial sleeves is not rotated 90 degrees
between sides, but
is placed consistently at both edge chords of the spacer block such as 290 in
FIG. 22B.
15 Biaxial modular connection sleeves allow the designer near limitless
variety in the
structural assemblies including wall blocks, box columns, paired blocks, and
trusses that
may be built into structural modules using repetitive identical elements.
Potential
configurations may include, but are not limited to, the following structural
elements. A
single block may used as a lightly loaded column and/or a pilaster for the
lateral support
of secondary exterior wall framing as illustrated in FIG. 11. A pair of blocks
10a and
lOb may connected at 90 degrees to form an "L" shaped element as illustrated
in FIG.
12. A series of blocks 10m-10p may be interconnected, by rotating alternating
blocks by
180 degrees in plan to align modular sleeves, to form a flat wall as
illustrated in FIG. 13.
A combination of blocks may also be used to construction a perimeter load-
bearing wall
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system of arbitrary shape as illustrated in FIG. 13B. A similar assembly that
also utilizes
additional blocks 10q-10r to form a pilastered wall system as illustrated in
FIG. 14. A
series of blocks 10s-10v may be interconnected at 90 degree angles to one
another to
form a ribbed wall system as illustrated in FIG. 15.
A rectangular or square box column 70 may be constructed from blocks 10w-10z
as illustrated in FIG. 16. Square box columns are formed by radial lapping of
block
edges, and rectangular box columns are formed by paired spacer blocks between
outer
blocks. Asymmetric blocks may also be used to construct asymmetric column
elements
290 as illustrated by FIG. 22B.
Biaxial sleeve connectors may be omitted in other embodiments where alternate
connection means, such as mechanical interlock, are provided for the
combination of
blocks into structural modules and completed structures.
Cross-section and Reinforcement Design
Concrete cross-sections, reinforcing steel bar sizes, and tie spacing may be
selected by the structural engineer on the basis of anticipated design forces
for a given
application. A block must be designed to safely resist stripping and handling
forces,
gravity loads, shears, lateral loads, and forces induced by the interaction of
the block with
other elements. This system is intended to give the design engineer
flexibility in the
selection of geometry, cross-sections and reinforcement as required for a
specific
application.
Construction of Block
In this embodiment, the construction sequence for stack-cast blocks is
designed to
yield easily and quickly erected structures. As noted above, sleeve assemblies
may be
pre-cut and tack-welded. Referring now to FIG. 9 which is a front view of
typical
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reinforcement for a block, reinforcing steel cages 220 are tied into units
using deformed
bar or wire ties. The ties may be standard cross-ties or they may spiral ties
225 as shown.
FIGs l0A-10E illustrate a stack casting procedure. FIG. l0A is a perspective
view
of a reinforcement cage step in a stack casting sequence. Reinforcing steel is
spaced and
held in position by the sleeve assemblies 100, which are in turn held in
position by sleeve
receivers 120 mounted on the forms 201. FIG. lOB is a perspective view of a
first level
form tying step in a stack casting sequence. After the tied cage 220 is
positioned in the
form 201 and 202 sleeve receivers 120, threaded rods 210 are temporarily
placed through
sleeves and forms, and nuts are tightened on rods to tie the side forms
together. FIG.
lOC is a perspective view of a first level concrete casting step in a stack
casting sequence.
For the first block 240 in a stack, the form set may be temporarily anchored
to a casting
slab or surface. Bond between the casting slab concrete and the element is
prevented by
use of a sheet membrane or common bond-breaker applied to the casting surface.
FIG.
lOD is a perspective view of an inverting forms step in a stack casting
sequence. After
casting and initial curing of the first block 240, forms are stripped, and a
bond-breaker is
applied to the top surface of the cast block. FIG. l0E is a perspective view
of a
subsequent level preparation step in a stack casting sequence. The forming
systems of this
embodiment is designed to facilitate stack-casting, and can incorporate
extension tabs 208
and spaced sleeve receivers 120 that allow a form section 201, 202 to be
inverted after the
first cast and the spaced receiver to be "snapped" onto the cast sleeve in the
first block
240. This positions the sleeve receiver at the correct location to receive the
sleeve and
reinforcing steel cage for the second block. This system allows multiple
blocks to be
stack-cast and consistently reproduced, one on top of another, quickly and
easily.
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Frame Components
The LadderBlockTM Building System derives its name from the most basic block
in the building set as shown in FIG. 1. The framing system consists of planar
elements
that form story-high rigid frames, and may be multi-story with multiple
lateral cells as
shown in FIGs 20A through 20I.
FIGs 20A through 20I are representative shapes of planar structural blocks.
FIG.
20A shows a simple rectangular block such as a one story block 230 which
includes a top
beam 34 having a cantilevered extension 50 on both sides.
FIG. 20B shows a rectangular block with cantilevered extensions 50 from each
side of an intermediate beam 32.
FIG. 20C shows a taller rectangular three story block 234 with cantilevered
extension 50, these cantilevered extensions typically serve as bearing
supports and are
designed to occupy recesses in the underside beams of interlocking floor
blocks (not
shown).
FIG. 20D shows a stepped block 236 which includes a first edge chord 21, a
second edge chord 22, an intermediate chord 23, a first top beam 36 between
the first
edge chord and the intermediate chord, and a second top beam 35 between the
second
edge chord and the intermediate chord. Typically the second top beam 35 is
used to
support high roof structural elements. The first top beam 36 is used to
support a low
sloped roof.
FIG. 20E shows an open rectangular block 238 without a base beam which is
omitted to allow pedestrian access without a tripping hazard.
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FIG. 20F shows rectangular element 240 which includes a sloped cantilevered
extension 52 from top beam 34. This combination of top beam 34 and extension
52 is
used to support a high roof with overhang.
FIG. 20G shows a simple block which includes a sloped top beam 34. FIG. 20H
shows a stepped block 244 with two sloped top beams 35 and 36 and an
intermediate
beam 23. This top beam configuration accommodates planar roof blocks of
opposing
slopes and clerestory windows for natural lighting.
FIG. 20I shows a planar block 246 with a first side edge chord 21, an offset
extension 51, a top beam extension 52 and an intermediate beam extension 50.
The ends
of these extensions are connected by a vertical chord 24. In some cases the
offset
extension 51 is above the surface and in some cases it is below the surface.
While base
beam 31 distributes loads to the supporting foundation, offset extension 51 is
intended to
cantilever beyond the supporting foundation edge with the top of the lower
extension at
the same elevation as the top of slab. The first edge chord 21 and the second
edge chord
22 may rest on a slab such that the first edge chord overhangs the slab. In
other
embodiments, the two edge chords may rest on discrete footings.
FIG. 21A shows a basic triangular block 260 having a first edge chord 21, a
top
beam 34 and a base beam 31.
FIG. 21B shows a wishbone spacer 280 having a first flange 281 and a second
flange 282.
FIG. 21C shows a segmented arc roof truss 300 having a first edge chord 301
and
a second edge chord 302, a base beam 311, and segmented top chords 304, 305,
306, and
307. In this example the roof truss includes the notches or daps 303 which are
typically
used to provide a horizontal bearing surface at truss supports. Referring
again to FIG.
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ZOF, the first edge chord 21 has an extension 28 which provides the horizontal
bearing
surface.
FIG. 21D shows a tied bowstring truss 319 with a segmented arch top chord 320,
a steel tie 321, a bearing seat 324 and a tapered key 322.
5 FIG. 21E shows a perspective view of a cap element 400, with side beams 401
and 402, box column split pockets 403 and 404, with a cross beam 405, and a
tapered key
receiver 406. FIG. Z1F shows a view of the underside of cap element 400.
FIG. 21G shows a corner cap element 410 incorporating a side beam 401. The
end 413 of a cap element is typically centered over a box column, such that
the ends 412
10 and 413 meet over a corner box column. FIG. 21H shows an underside view of
the
corner cap element 410.
FIG. Z1I and 21J show top side and underside views of another embodiment cap
element 409 that features simple cross beams 405, split box column pockets 404
and box
column pockets 420 that center over a box column, and cantilevered extension
422.
DETAILED DESCRIPTION OF EMBODIIVVIENT -Structural Modules
In one embodiment, these structural blocks are typically combined into
structural
modules such as box column 70 as shown in FIG. 16 and other examples discussed
below.
FIG. 22A is an exploded perspective view of a paired roof truss module 440
which comprises a pair of segmented arc roof trusses 300 joined by wishbone
spacers
280. In this example the segmented arc roof trusses are held in rigid parallel
alignment
by the wishbone spacers such that they form a laterally stable structural
module that may
be preassembled at ground level and hoisted into position as a unit. In this
example the
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module is assembled by a threaded connectors inserted through beam or chord
elements
308 and wishbone spacer flange such as 281. Other connection schemes may be
used.
FIG. 22B shows an asymmetric box column 450 formed by a pair of stepped
blocks 246, a rectangular block 248, and a rectangular block 290 with bolted
edge chord
extensions 291 and 292. The bolted edge chord extensions work in conjunction
with edge
chord extension 28 of stepped block 246 to form a keyed and bolted bearing
seat for
paired roof truss module 440. This mating is shown in perspective in FIG. 2~.
One embodiment will employ at least two basic methodologies of combining
structural modules to form complete building structures. One method, as
depicted in
FIGs. l~ and 32B, can be characterized as base modules such as 70 and 450
supporting
discrete roof blocks or modules such as 15 or 440. A second method
incorporates cap
blocks such as 400 and 409 of FIGs. Z1E and 21I spanning between and bearing
on base
modules to support a series of more closely spaced roof framing blocks, as
shown in
FIGs. 33D and 35B.
DETAILED DESCRIPTION OF EMBODIIVVIENT - Wall Blocks
FIG. 23A shows a framed wall block 460 with light gauge metal wall framing, an
inside surface 462 and outside surface 461. Metal wall blocks on both faces of
the block
provide finished surfaces and stressed skin panel rigidity for handling of the
block. In a
design environment that generally emphasizes the most efficient use of
materials possible,
the use of metal panels on both faces of a wall element in an industrial
building is non-
obvious. The incorporation of the inner skin brings significant benefit by
creating a
stressed-skin panel that is structurally redundant and is of sufficient
durability to resist
lifting and handling forces on the block and to carry reactions back to
discreet and simple
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connections, thus allowing ease and speed of assembly and disassembly. This
feature
enables the wholesale recycling of buildings without visits to the landfill,
as well as
enabling the rapid erection of quality buildings where needed, as in the case
of an
emergency relief shelter. FIG. 23B shows an inside view of the wall block
shown in FIG.
23A.
FIG. 23C shows an exterior view of three varieties of precast wall blocks 470,
471, and 472, and depicts a cast pattern that emulates stacked stone. FIG. 23D
shows an
inside view of the same three blocks. These blocks feature flanges such as 473
to
interlock with beam elements of the LadderBlock frame. In another embodiment,
keyed
interlock connections are omitted in lieu of bolted flange connections through
LadderBlock sleeves.
FIG. 23E shows hinged wall blocks 475. FIG. 24A is a view of the interior
framework 465 of another embodiment of a framed wall block 464. The framework
includes bent plate clips 466 which typically engage box column beams. FIG.
24B shows
the framed wall block of FIG. 24A with inner and outer metal skins installed.
FIG. 25A is a perspective view of an assembled wall block on open box columns.
The wall block 464 may be hung on cross beams 32 of LadderBlock 248 which is
part of
open box column 451. FIG. 25B is a detailed view of this hanger connection.
Heavy
precast wall blocks and framed wall blocks that are restrained against upward
movement
by roof elements may rely solely on interlock for connectivity to the base
structure, but
wall blocks that do not meet these criteria must be bolted to the supporting
structure to
ensure competence under high wind loads.
DETAILED DESCRIPTION OF EMBODIMENT - Roof Blocks
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FIG. 26A is a top view of precast roof blocks 480 and 482. FIG. 26B is an
underside view of those same blocks, and shows tapered beam 481 which is
upslope of
beam 484. These beams serve to carry joists 483 and bear on LadderBlock module
beams
at bearing seats 485. In most applications, the mass and interlock of precast
roof blocks
offer sufficient connection to the supporting structure such that mechanical
connectors
may not be required.
FIG. 27A is a perspective view of steel framing 492 for framed roof block 490.
These lighter blocks require bolted connection clips 493 to resist wind uplift
pressures;
these clips are shown projecting from the underside of the framing in FIG.
27A. FIG.
27B shows a perspective view of framed roof block 490 with metal panels
installed. As
with framed wall blocks such as 460, framed roof blocks 490 typically
incorporate an
inner and outer structural skin to enable lifting and handling of the block.
FIG. 27C is a
detail view of a bolted connection clip b, and FIG. 27D shows an underside
view of the
completed roof block 490.
FIG. 28 shows an assembly of a roof block 490 on an asymmetric column 450 as
shown in FIG. 22B. The roof block is mounted on top beams 34 of stepped block
246
with bolted connection clips 493.
DETAILED DESCRIPTION OF EMBODIMENT - Floor Blocks
FIG. 29A shows an assembly of two box columns 70 fitted with bolted haunches
76 carrying floor support blocks 496 which in turn support framed floor blocks
494.
Bolted haunches 76 are shown in detail in FIG. 33B.
FIG. 29B shows three winged box columns 74 each comprised of pair of blocks
232 and a pair of rectangular blocks 10. The winged box columns are shown
supporting
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two interlocking interior spans of precast floor block 486 and one precast
floor end block
488. FIG. 29C shows a top view of these two floor blocks and FIG. 29D shows an
underside view of the same blocks. The beam configuration on the underside of
these
precast floor blocks forms receiving pockets 489 for bearing on cantilevered
beam
extension of blocks 232.
FIG. 30A is an exploded view of a three part precast floor block assembly
consisting of interior block 500, infill frame 506, and infill plank 504. FIG.
30B shows
an underside view of this precast assembly installed on stepped blocks 510.
DETAILED DESCRIPTION OF EMBODIIVV1ENT - Erection of Modules
Upon completion of casting, blocks are allowed cure until concrete has gained
the
necessary strength to resist lifting and handling forces. The initial lifting
operation must
break the suction andlor bond forces on the down-cast face of the element.
Stripping
forces can represent the most severe loading to which a block will ever be
subjected. On
blocks that are too slender to strip from upper lifting sleeves (as shown in
FIG. 2A)
without damage to the element, stripping may be accomplished by using a strong-
back (as
illustrated in FIG. 2B) that simultaneously lifts from several of the chord
sleeves. Once
the block is broken loose from its casting surface, typically a casting slab
or an underlying
stack-cast element, it is lifted into vertical position by crane rigging that
utilizes cast-in
sleeves as lifting points. Slender blocks may require the use of a strongback
during
lifting, or they may be interconnected to one or more perpendicular blocks
while still laid
flat.
A stiffened structure that is formed of interconnected blocks will be more
easily
erected. The risk of damage due to lifting stresses is reduced and the
structural assembly
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is more likely to be independently stable without the need of temporary
bracing. The
weight of the example embodiment is on the order of 3,500 lb, and a four-block
box
column weighs 7 tons, so that only a light crane is required to lift these
elements.
After lifting, the block or assembly is set in its designated position.
Referring now
5 to FIG. 11, base connections on a slab 50 may consist of pre-set anchor
bolts or drilled
and epoxy or grout-set threaded rods that pass through base sleeves 103 and
are tensioned
using nuts in combination with oversized washers or spreader plates. An
erected block
that has not been assembled into a structural module can be temporarily braced
using
diagonal struts that are perpendicular to the face of the block, by immediate
connection to
10 other stable blocks; but the preferred construction method using this
system will consist
of the assembly of multiple blocks into independently stable modules prior to
lifting.
When they are required, temporary struts may connect using modular sleeves and
temporary anchors to the slab. Final construction will typically employ
interconnected
assemblies of perpendicular blocks or lateral bracing via secondary members
52.
15 Interconnection of blocks is accomplished using washers and nuts in
conjunction with
standard length threaded rods that pass through modular connection sleeves.
Secondary
elements such as wall gins, roof purlins, or miscellaneous framing may be
similarly
connected at modular connection sleeves. In a building that incorporates wall,
floor and
roof blocks of this system, girls and purlins are replaced with blocks of
construction that
20 are built at ground level, lifted into position with a light crane, and
connected to the
structural frame be means of interlocking or simple bolted or interlocking
connections.
This system is designed to allow forces to be distributed over a relatively
large
area at the base of a structural assembly and to receive forces from multiple
sources at the
top of an assembly, such as roof framing and rail beam for bridge crane
carried on a
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single box-column assembly, while concurrently providing an element with
inherent
lateral stability and the potential for a flexible range of secondary
functionality. For
example, blocks may carry intermediate floors or industrial shelves, and
closed box-
column sections may house storage space, mechanical rooms, restrooms,
elevators or
other building functions.
Load Bearing Capacity
The LadderBlock building system is designed to allow the economical
construction of structures that can safely carry loads that are much greater
than most
conventional building systems are designed to carry. By building to provide
structural
capacities that are significantly in excess of those required to resist the
minimum loads
required by building codes, new opportunities are created in the functionality
and
versatility of the built structure. Buildings of this construction can
generally carry high-
load floors, support heavy hinged-panel operable walls, provide support for
hoisting
systems, and carry future levels of floor structure without modification to
the original
structure. This reserve structural capacity is achieved economically through
the straight-
forward, repetitive construction at ground level of identical pre-engineered
blocks.
Construction Stability and Speed
Although blocks may be combined in a variety of configurations, the basic
methodology at play in this building system is the interconnection of
manufactured blocks
to form independently stable structural modules; these modules generally form
three-
dimensional mufti-sided frames. Precast blocks are generally open frameworks
with rigid
joints at member intersections. They are made of structural-grade castable
material such
as concrete and are reinforced, such as by rebar, as indicated by an
engineering analysis
for a given application. Precast and framed blocks are designed to be easily
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interconnected to form independently stable structural modules. This enables
the
construction of structural modules that can be set in position with a light
crane and
immediately let go, without the need for installation of temporary lateral
bracing prior to
releasing the hoist lines, as is necessary with tilt-wall construction. This
feature allows
expensive crane time to be utilized very efficiently; the crane can continue
setting
structure if it is not needed to stabilize inherently unstable parts while
they are being
braced. Once set in position and anchored as required to the supporting
structure,
independent structural base modules serve to resist both gravity and lateral
loads with an
open but stable and structurally redundant framework.
Construction Safety
Independent base modules are typically interconnected with roof and/or floor
construction that generally consists of other pre-assembled modules that are
themselves
independently stable. The independent modules effectively create large-scale
building
blocks that may be erected and will stand stable without the need for
temporary shoring
or bracing, in contrast to conventional construction that relies on diagonal
bracing or
shear walls for lateral stability. By building with large, independently
stable blocks made
of interconnected precast parts, construction may progress much more rapidly
and safely.
By eliminating the need for lateral bracing and shoring, the construction site
can be kept
clear of obstructions that contribute to many construction accidents. Because
LadderBlock parts are built at ground level, and can generally be
interconnected into
modules at ground level, elevated work and the associated falling hazards are
minimized.
The structural redundancy provided by building with independently stable
blocks should
also significantly enhance the performance of the overall building if
subjected to a
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collapse-initiating overload; redundancy is the best insurance against
progressive and
total collapse of a building structure.
Distribution of Base Forces
In contrast with conventional construction techniques that concentrate forces
to
conserve usable floor space, this system intentionally distributes these
forces across a
wide base that minimizes stresses on the supporting surface. By building this
base so
wide that the volume enclosed by the structural element is itself usable
space, this
structural advantage can concurrently offer functional advantages.
The wide distribution of base forces, and the attendant lowering of base
pressures,
generally allows a LadderBlock structural module to be directly supported on
~a stiffened
slab-on-grade where similar load carrying capacity would normally require
special and
costly foundations. As a building gets taller, it must resist larger wind
pressures and
forces that generate shears and overturning moments at the base of the
structure. Because
these overturning moments are also distributed across a wide base, the tie-
down
connections required to resist overturning at the base of a LadderBlock
structural module
may be of lighter and less costly construction than might otherwise be
necessary. If the
supported structure is of sufficient weight and is not subjected to seismic
loads, it may not
require tie-downs at all. The selection of LadderBlock components from which
to build a
structure, the analysis of load paths through that structure, and decisions
regarding tie-
down requirements are all subject to the required structural engineering
analysis of the
overall structure for a given application.
The supporting surface to which a structural module is tied down may consist
of
an underlying layer of structure or a stiffened concrete slab. In light-use,
low-rise
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construction, the supporting surface may consist of nothing more than a level
pad of
compacted fill or natural soils that exhibit adequate bearing capacity and
stability.
Assemblies of blocks may be utilized for functions beyond that of the primary
structural system for a building. Beam elements 75 and 76 between block
columns, pairs,
or individual blocks may be utilized to support intermediate levels of
occupied floor
space or large-scale industrial shelf space as illustrated in FIG. 17. The
vertical shaft
within an appropriately sized box column 70 may be utilized as the framework
for an
elevator, as multi-level storage closets that can be loaded with a forklift,
or as a plenum
for mechanical, electrical, or plumbing systems. Additionally, assemblies of
blocks can
provide the required structural capacity to support bridge cranes, jib hoists,
and other
lifting devices without the need for additional structure.
DETAILED DESCRIPTION OF EMBODIIVVIENT - Structural frames and shells
FIG. 18 shows a sample of a completed primary structural frame that is built
using this system. In that example, a plurality of box columns 70 support roof
trusses 15.
Additional elements such as wall blocks and roof blocks may be attached to the
structural
frame.
FIG. 19 shows the frame of FIG. 18 carrying secondary framing in the form of
roof purlins 18 and wall girls 19, prior to installing remaining minor framing
and the
exterior skin that completes the building envelope.
FIGs 31A to 31D show a sequence of assembly of an enclosed structural shell.
In
this example, three modules 520 as shown in FIG. 31A are set on a support
surface, such
as a compacted fill pad. Each of these modules 520 is comprised of stepped
blocks 244
and two rectangular blocks 243 and 245. The blocks are stable and self
supporting when
set into position, and are ready to receive floor blocks 494 and 496 as
illustrated in FIG.
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31B, wall blocks 522, 524, and 526 as illustrated in FIG. 31C, and roof blocks
528 and
529 as show in FIG. 31D.
Another example is illustrated in FIGs 32A through 32D. In this example, six
modules 450 are set so that they partially overhang a slab 540. FIG. 32B shows
5 suspended access floor blocks 541 and paired roof truss modules 440 prior to
installation
of wall and roof blocks. FIG. 32C shows installed wall blocks 542 and 543,
clerestory
blocks 544, wall header blocks 545, and sliding door blocks 546. FIG. 32D
shows the
enclosed structural shell completed by the installation of roof blocks 550.
FIGs 33A through 33E represent a structural shell of an open industrial
building
10 of box columns 70 supporting two upper levels of framed floor blocks 494,
and shows
passage floor blocks 495 to receive stair units 497. FIG. 33A shows the box
columns
erected, FIG. 33B provides a detail view of bolted haunches, and FIG. 33C
shows the box
columns 70 carrying framed floor blocks 494. FIG. 33D shows the primary frame
with
solid cap blocks 408 carrying tied bowstring trusses 319. FIG. 33E shows the
near
15 completed structure after installation of precast wall blocks 552, metal
wall studs 554,
and metal roof deck 558.
FIG. 34A and 34B show another example of a mufti level structural shell
including a slab 540, box columns 70, and an assortment of winged box columns
of
various heights 560, 562, and 564. These box columns support floor modules 486
and
20 488, and cap blocks 409. The box columns also support hinged wall blocks
475.
FIGs 35A though 35D show another example of a structural shell. In this
example
box columns 70 and asymmetric walk through box columns 580 are provided. The
walk
through box columns 580 provide walk up access to the interior of the box
column to
allow utilization of this space. The cap elements 400 and corner cap elements
410 are
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used to support roof trusses such as 319. The asymmetric box columns 580
support
concrete roof blocks 480 and 482 which provide fire resistant structure at low
roofs. The
upper roof shown in FIG. 35D consists of framed roof blocks 490 and clerestory
roof
blocks 499.
