Patent application title: Method and apparatus for precast wall and floor block system
David W. Powell (Austin, TX, US)
IPC8 Class: AE04B1343FI
Class name: Static structures (e.g., buildings) barrier or major section mounted for in situ repositioning; e.g., rearrangeable or rotatable barrier of hingedly connected sections
Publication date: 2008-11-20
Patent application number: 20080282623
Patent application title: Method and apparatus for precast wall and floor block system
David W. Powell
RICK B. YEAGER, ATTORNEY
Origin: AUSTIN, TX US
IPC8 Class: AE04B1343FI
Precast planar construction wall blocks are provided with various
configurations of fingers. Structures are rapidly assembled by aligning
the fingers and inserting a pin through vertical sleeves provided in the
fingers. Finger joints are typically shimmed and grouted for additional
strength. Openings for doors and windows are provided in some wall
blocks. Floor blocks are supported on ledges at the top of wall blocks or
by portions of the top edges of wall blocks. A concrete or other topping
may be added to floor blocks, and conduit may be run in the topping.
1. A structure assembled from a plurality of precast blocks, the structure
comprisinga first floor comprisinga first corner connection betweena
first block having a complementary finger arrangement of fingers with
vertical sleeves, anda second block having a different complementary
finger arrangement of fingers with vertical sleeves, the corner
connection comprisinga pin inserted through the vertical sleeves of the
first block fingers and the vertical sleeves of the second block fingers.
2. The structure of claim 1 wherein the corner connection further comprisesa plurality of shims placed between adjacent fingers.
3. The structure of claim 2 wherein the corner connection further comprisesgrout placed around the shims and between adjacent fingers.
4. The structure of claim 1 further comprisinga tee connection betweena third block and a fourth block having a complementary finger arrangement of fingers with vertical sleeves, anda fifth block having a different complementary finger arrangement of fingers with vertical sleeves, the tee connection comprisinga pin inserted through the vertical sleeves of the finger elements of the third block, the fourth block, and the fifth block,a plurality of shims placed between adjacent finger elements, and grout placed around the shims and between adjacent finger elements.
5. The structure of claim 1 further comprisingat least one floor block supported by the first block and another block; anda second floor comprising a plurality of wall blocks with fingers, such that the wall blocks are connected by finger joints.
6. The structure of claim 5 whereinthe first block comprises a ledge; andthe floor block is partially supported by the ledge.
7. The structure of claim 5 whereinthe first block comprises a plinth that extends above the floor block; andanother block, comprising a bottom edge with a grove, is positioned such that the plinth is aligned with the groove.
8. The structure of claim 5 whereinthe floor block is partially supported by approximately one half the width of a top edge of the first block.
9. A method of assembling a structure from a plurality of precast wall modules, the method comprisingproviding a plurality of groups of intersecting wall blocks, each group comprisinga first set of at least one wall block, such that the first set has a complementary finger arrangement, anda second set of at least one wall block, such that the first set has a complementary finger arrangement, such that the first set and the second set form a complementary mating arrangement;assembling a first floor of the structure by, for each group of intersecting wall blocks of the first floorpositioning a first block from the first set,positioning a second block from the second set,determining whether the first block and the second block represent all of the intersecting wall blocks for the group and if the first block and the second block represent all of the intersecting wall blocks for the group, then inserting a pin through the vertical sleeves of all of the intersecting blocks for the group,otherwise inserting pipes between adjacent fingers of the positioned blocks for the group, thereby providing temporary support, andcontinuing to sequentially position and temporarily support remaining blocks from the first set and second set until all blocks for the group are positioned, and then inserting a pin through the vertical sleeves of all of the intersecting blocks for the group.
10. The method of claim 9 further comprisingshimming and grouting each finger connection of the groups of intersecting wall blocks of the first floor.
11. The method of claim 9 further comprisingsetting a plurality of floor blocks, such that the floor blocks are supported by at least a portion of the groups of intersecting wall blocks of the first floor.
12. The method of claim 10 further comprisingassembling a second floor of the structure by, for each group of intersecting wall blocks of the second floorpositioning a first block from the first set,positioning a second block from the second set,determining whether the first block and the second block represent all of the intersecting wall blocks for the group andif the first block and the second block represent all of the intersecting wall blocks for the group, then inserting a pin through the vertical sleeves of all of the intersecting blocks for the group,otherwise inserting pipes between adjacent fingers of the positioned blocks for the group, thereby providing temporary support, andcontinuing to sequentially position and temporarily support remaining blocks from the first set and second set until all blocks for the group are positioned, and then inserting a pin through the vertical sleeves of all of the intersecting blocks for the group.
13. A precast wall block comprisinga block portion having a top edge, a bottom edge, a first side edge, and a second side edge;a plurality of spaced-apart fingers projecting from the first side edge in a first finger orientation, each finger comprisinga top face,a bottom face, anda vertical sleeve having a top portion recessed from the top face of the finger and a bottom portion recessed from the bottom face of the finger; andreinforcement elements affixed to each sleeve and extending into the block portion, such that the reinforcement elements reinforce the finger and the sleeve.
14. The precast wall block of claim 13 wherein the reinforcement elements further comprisea pair of hairpin reinforcement bars.
15. The precast wall block of claim 13 wherein the first finger orientation is complementary.
16. The precast wall block of claim 13 further comprisinga plurality of spaced-apart fingers projecting from the second side edge in a second finger orientation, each finger comprisinga top face,a bottom face, anda vertical sleeve having a top portion recessed from the top face of the finger and a bottom portion recessed from the bottom face of the finger; andreinforcement elements affixed to each sleeve and extending into the block portion, such that the reinforcement elements reinforce the finger and the sleeve.
17. The precast wall block of claim 16 whereinthe second finger orientation is complementary and is different from the first finger orientation.
18. The precast wall block of claim 16 whereinthe second finger orientation is complementary and is same as the first finger orientation.
19. The precast wall block of claim 9 whereinthe block portion has a front face; andeach finger has a front face inset from the front face of the block portion.
20. The precast wall block of claim 9 further comprisinga groove in the bottom edge extending from the first side edge to the second side edge; anda tongue in the top edge extending from the first side edge to the second side edge.
This non-Provisional patent application is related to U.S.
Provisional Application 60/930,229 which incorporated by reference
Provisional Application 60/923,265. Application No. 60/930,229 was filed
by applicant on May 15, 2007. This application claims the priority of the
May 15, 2007 filing date.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to a building system comprising precast structural building wall and floor 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
LadderBlock® Precision Precast Framing and Wall Systems
LadderBlock® precision precast framing and wall systems have been described in previous applications including copending U.S. patent applications Ser. Nos. 10/680939, 11/332696, and 11/745,998; and related PCT applications PCT/US03/31929, PCT/US/06/01429, and PCT/US07/68498. The current application describes a precast wall system that can be used to build perimeter or interior wall components that are supported by and complement the LadderBlock framing system, or that can stand alone as a load-bearing wall system.
State of the Art in Precast Wall Systems
There are a number of conventional and precast wall systems on the market, but these systems generally rely on either cast-in-place joints or embedded steel assemblies and welded connections to provide structural connectivity between precast elements. In the cast-in-place joint systems, precast elements are assembled and braced as required to allow site-cast concrete to form the connection between elements. These systems have the disadvantage of shoring requirements and limited stability until the cast-in-place joints have been placed and the concrete allowed time to gain strength. In the more common welded joint systems, the erecting crane must support the newly installed component until its welded connections are made to provide stability. These prior art systems are inefficient in the utilization of costly crane time, and rigidly welded joints tend to perform poorly in the presence of the thermal movements that affect all structures. The need exists for a precast wall system that allows immediate stability without cast-in-place or welded joints, the speed of erection that accompanies the elimination of these processes, and sufficient flexibility to allow a structure to undergo limited thermal movements without joint distress.
SUMMARY OF INVENTION
The current invention provides precast wall blocks that can quickly be assembled into single or multiple story structures. The planar construction wall blocks are provided with various configurations of fingers so that a variety of structures may be assembled by aligning blocks and pinning the finger joints. Structures are rapidly assembled by aligning the fingers and inserting a pin through vertical sleeves provided in the fingers. Temporary bracing is typically required only for a first block.
Finger joints are typically shimmed and grouted for additional strength. Openings for doors and windows are provided in some wall blocks. Floor blocks are supported on ledges at the top of wall blocks or by portions of the top edges of wall blocks. A concrete or other topping may be added to floor blocks, and conduit may be run in the topping.
The wall blocks may be designed for a particular application, or inventories may be maintained of standard wall lengths and features such as door and window locations. In one embodiment, a tongue and groove base key detail supports the stacking of wall blocks for multi-level construction. Only the first block installed at each level in an assembly should require any temporary bracing, and each subsequent block enjoys immediate stability when the pin is installed.
DESCRIPTION OF FIGURES
FIG. 1 is a front perspective view of a wall block with fingers.
FIG. 2 is a detailed front perspective view of a finger of FIG. 1.
FIG. 3 is a front perspective view of a plurality of wall blocks assembled to form a wall of varying height.
FIG. 4 is a front perspective detailed view of a second wall block being placed over a first wall block.
FIG. 5 is a front perspective detailed view of a fourth wall block being placed relative to a first, second, and third wall block. The fourth block is shown in a raised orientation.
FIG. 6 is a front perspective detailed view of the fourth wall block of FIG. 5 lowered into position relative to the first, second, and third wall blocks.
FIG. 7 is a top perspective view showing a pin inserted into finger recesses of two wall blocks forming a corner.
FIG. 8 is a front perspective detailed view of a sleeve in the fingers of a first wall block, and of a cross-shaped sleeve in the fingers of a second wall block.
FIG. 9 is a front perspective detailed view of typical reinforcement for fingers in a wall block.
FIG. 10 is a top perspective view showing a pin being inserted into finger recesses of two wall blocks forming a corner.
FIG. 11A is a perspective view of two wall blocks forming a corner, and a floor block.
FIG. 11B is a perspective exploded view of the wall blocks and floor block of FIG. 11A.
FIG. 12 is a perspective view of a first finger position configuration.
FIG. 13 is a perspective view of a second finger position configuration.
FIG. 14A is a perspective view of wall blocks forming a straight wall.
FIG. 14B is a perspective view of wall blocks forming a corner.
FIG. 14C is a perspective view of wall blocks forming a tee shaped wall.
FIG. 15 is a perspective view of a third finger position configuration.
FIG. 16 is a perspective view of a fourth finger position configuration.
FIG. 17 is a top perspective view of a cross-shaped wall section formed by four wall blocks, and a Y-shaped wall section formed by three wall blocks.
FIG. 18 is a perspective view of a plurality of wall blocks and LadderBlock® elements.
FIG. 19 is a perspective view of three wall blocks supporting two floor blocks.
FIG. 20 is a perspective view of a concrete topping over a portion of a floor block.
FIG. 21 is a front perspective view of finger joints with shims.
FIG. 22 is a front perspective view of finger joints of FIG. 21 showing the insertion of a shim.
FIG. 23 is a perspective view of a plurality of wall blocks with a pilaster positioned for insertion.
FIG. 24 is a perspective view of a plurality of wall blocks assembled to form a structure.
FIG. 25 is a perspective view showing tee and cross connections.
FIG. 26 is a perspective view showing blocks with complementary finger patterns.
FIG. 27 is a perspective view showing a seven block connection.
FIG. 28 is a front perspective view of a finger joint.
FIG. 29 is a front perspective view of a finger joint failure showing shearing of a pin connector at two planes.
FIG. 30 is a detailed perspective view of a finger joint failure showing breakage of reinforcing steel hairpins.
FIG. 31 is a partially exploded view of a structure with various finger blocks.
FIG. 32 is an assembled structure of FIG. 31.
FIG. 33A is an exploded perspective view of an example structure with relief features.
FIG. 33B is an assembled structure of FIG. 33A.
FIG. 34 is an exploded view of a structure with a rigid frame block.
FIG. 35 is an assembled structure of FIG. 34.
FIG. 36 is an exploded view of a structure with beam blocks.
FIG. 37 is an assembled structure of FIG. 36.
FIG. 38 is an exploded view of a structure with exterior and interior offsets.
FIG. 39 is an assembled structure of FIG. 38.
FIG. 40 is a front perspective view of conduit placed over a floor block and covered with a floor topping.
FIG. 41 is a front perspective exploded view of a two story structure showing the stacking of wall corner blocks.
FIG. 42 is a front perspective assembled view of the structure of FIG. 41.
FIG. 43 is a perspective view of a wall block 100.
FIG. 44 is a perspective view of several potential wall block structure profiles from a single block type.
FIG. 45 is a perspective view of a pedestal support.
DETAILED DESCRIPTION OF INVENTION--FINGER WALL SYSTEM
The Finger Wall system described herein combines the speed of sleeve and bolted joint construction inherent in the LadderBlock framing system with the redundancy and strength of a finger joint detail that is common to fine woodworking, such as furniture and cabinet construction. It eliminates cast-in-place and welded joints, and replaces them with aligned sleeves that receive a common pin for immediate stability. Two wall blocks so joined at right angles to one another form a structure that is similar to a door hinge stood on its edge. By building these finger joints at each end of a series of wall blocks, and adding the ability to easily build standard receiving stations along the length of a wall, a building of any footprint can be constructed. By standardizing wall lengths and door and window locations and offering the ability to incorporate those standard elements into an unlimited variety of plan layouts, this system can enable high quality construction to be manufactured and built out of inventory with exceptional speed. The system enables the support of floor blocks on one or both sides, and it incorporates a base key detail that makes the wall blocks stackable for multi-level construction. Because the basic stability of the structure is gained as soon as the pin is installed, the assembly of finger wall blocks can progress with remarkable speed and safety. Only the first block installed at each level in an assembly should require any temporary bracing, and each subsequent block enjoys immediate stability when the pin is installed. The temporary bracing is typically removed after a second block is connected to the first block. The joints can then be grouted for fixity at the installer's leisure, and this work can be done without incurring the expense of crane time and within the safety of a stable structure. Where tall construction is desired, vertical and or horizontal ducts can be cast into the finger wall blocks to accommodate post-tensioning systems.
By utilizing a standardized joint detail and geometry, the forming system for the production of these wall components can be made very efficient and flexible. Although a standardized finger wall block set offers the greatest advantages in manufacturing economy, the system lends itself to customized block sets that are built with standard forming elements placed in a continuous form bed, so that any desired floor plan can be built with relative economy. If the option for future reconfiguration or disassembly is desired, joints can be filled with removable material that could consist of softer mortars, dry wedge systems, or any other filler that is capable of transferring the necessary structural forces through the joint. This allows for the potential recycling and reuse of an entire structure, so that finger wall blocks should never see a landfill.
The finger wall system offers the potential to produce sets of precast building blocks that use standardized finger and horizontal joint details to enable the rapid and safe construction of structures that offer inherent stability and structural redundancy. Joint features can be economically cast with a high level of precision because of their standardization, so that the fit-up and interchangeability of parts is ensured.
A "finger" is defined as a reinforced extension from the side edge of a pre-cast wall block. The finger typically has a top surface, a bottom surface, a vertical sleeve between the top surface and the bottom surface. The sleeve has reinforcement extending at least partially into the main body of the wall block.
In the examples discussed below, the fingers are sized so that they are slightly less than one tenth the height of a standard wall block. A "finger position" is defined for purposes of illustration in this example as a number between one and ten where one represents the uppermost possible finger and ten represents the lowest possible finger.
Finger Pattern A" is defined as all of the odd numbered finger positions. This finger pattern may be presented by a single block, or by two or more blocks.
Finger Pattern B" is defined as all of the even numbered finger positions. This finger pattern may be presented by a single block, or by two or more blocks.
A "general mating finger arrangement" is any combination of blocks, each block having one or more fingers, such that the fingers of the blocks do not interfere.
A "preferred mating finger arrangement" is achieved when all intersecting blocks provide at least one finger element and all finger positions are occupied. In order to reduce the number of different block designs, it is generally desirable to further constrain the finger orientation of each side edge of a block to all or a portion of either finger pattern A or B.
A "complementary finger arrangement" is defined as a set of one or more blocks having a total number of finger positions on mating edges that is either a "finger pattern A" or "finger pattern B" configuration. As described below, a tee connection may be made between a single interior wall block having a finger pattern A complementary finger arrangement, and two exterior wall blocks having a finger pattern B complementary finger arrangement. In the case of a corner connection between two blocks, each block would typically have a different "complementary finger arrangement"--one block would have a finger pattern A and the other block would have a finger pattern B.
A "complementary mating finger arrangement" is defined as a first set of one or more blocks having a finger pattern A, and a second set of one or more other blocks having a finger pattern B. For instance two corner blocks can have a complementary mating finger arrangement when a first block has a finger pattern A, and a second block has a finger pattern B. Although this example has used ten fingers, other numbers of fingers can be used, and it is not necessary for the number of total finger positions to be an even number--for instance Pattern "A" could have an even number of fingers; and Pattern "B" could have one less or one more finger position than pattern "A". A tee connection such as the intersection of a pair of exterior wall blocks with an interior wall, can have a desired complementary mating finger arrangement when the pair of exterior wall blocks form either a finger pattern A or a finger pattern B, and the interior wall block provides the mating B or A finger pattern. A cross connection can have a desired complementary mating finger arrangement when a first set of two wall blocks form either a finger pattern A or a finger pattern B, and a second set of wall blocks provides the mating B or A finger pattern. One aspect of the current invention is the opportunity to design of a minimum number of different wall blocks by considering how the blocks will be assembled, and appropriately assigning all or a portion of an A or B pattern to the various block edges.
A "group" is defined as all blocks which share a common intersection. A group comprises two sets of at least one block in each set. Preferably, each set has a complementary finger arrangement-one set with finger pattern A and one set with finger pattern B.
A "finger joint" is defined as a pinned connection between the fingers of different wall blocks. The joint is typically shimmed and grouted.
A "shear key" is defined as the volume between two adjacent finger joints and includes recesses in the top of one finger and the bottom of the other finger. This volume is typically filled with mortar or grout.
A "base key" is a feature such as a tongue and groove connection that interlocks levels of stacking of wall blocks.
Finger Joint Details
Finger joints consist of sets of dimensionally standard and internally reinforced fingers at each end of a block 100 as shown in FIG. 1. Each finger offers a reinforced sleeve 111, 121, 131 that aligns with identical sleeves in the lapping fingers of a connected wall block, and recesses 112, 113 cast in the horizontal surfaces of each finger as shown in FIG. 2 produce shear-resisting interlock when the joint is filled with grout or mortar. In the example embodiment, fingers are nominally 30 cm long and 30 cm tall within a 30 cm thick wall block. Nominal dimensions are reduced by joint widths that provide the installation and finish tolerances discussed below. Fingers in the example embodiment are centered at 60cm vertically at a given end of a wall block, and interlaced fingers of connected wall blocks at a joint are spaced at 30cm vertically. Which fingers from a wall block extend into a given joint is coordinated by joint type, as described below. Other finger dimensions and spacings are possible, but in the example embodiment compatible finger wall blocks can be produced in any height that is an increment of the 60 cm finger spacing; for example, finger wall blocks 100, 101, 102, 103, 104, and 105 of 2.4 m, 3.0 m, and 3.6 m can all interconnect within the same structure using the described finger geometry as shown in FIG. 3.
Horizontal Joint Details
Referring to FIG. 4, the top of each finger wall block 100 can be cast with a chamfered tongue 200 that interlocks with the base of the wall block 106 above; the bases of both blocks can be cast with a standard groove 202 that fits the tongue. The overlap of the tongue and groove detail offers horizontal shear resistance and interlock to accompany that provided by the pinned and grouted connections to joined wall blocks, which may be connected at each end of a block or anywhere along its length. Ultimately, lateral forces are resisted by the interconnection of intersecting wall blocks at finger joints, and the horizontal keyed joints prevent relative sliding of wall blocks between ends. In other examples discussed below, a floor block support ledge is provided on one or both sides of the tongue, and the portion of the tongue that extend above the floor blocks is termed a "plinth" or "continuous plinth".
Installation and Finish Tolerances
Finger joints are typically undersized by a dimension that is coordinated with the height of the horizontal keyed joints. This allows each wall block to be hoisted into position with its fingers high within each intersecting joint as shown in FIG. 5, and then set down onto the keyed base joint as shown in FIG. 6. This technique permits a block to be inserted over a tongue or plinth and then lowered into position. In FIG. 5, block 101 with fingers 160 and 170 has been set, and block 100 with fingers 110 and 120 is raised. When block 100 is lowered as shown in FIG. 6, the block 100 fingers 110 and 120 are centered within the voids 131, 132, and 133 that are left between the mating fingers of the intersecting wall block. Faces of each finger 141, 142, 143, 151, 152 can be held back from the faces 140, 150 of the wall blocks as shown in FIG. 7 and left rough to receive a grout or stucco finish, so that the joints can be obscured from view.
A critical feature of the finger joint is the aligned sleeves that are presented within each finger. Sleeves may be vertical only such as shown by sleeve 110 in FIG. 8 and held in position by the finger forms, or they may consist of crosses as shown by sleeve assembly 303 in FIG. 8 which is similar to the biaxial sleeves disclosed in association with patent descriptions of the LadderBlock framing system. In this example, the cross sleeve assembly comprises a vertical sleeve 301 and a horizontal sleeve 302. Vertical sleeves are confined within the internal reinforcing steel of the finger, as described below.
Finger wall blocks can be reinforced as required by structural analysis, but blocks will generally feature a layer of reinforcing bars or mesh near each face, with additional reinforcement as required around each door and window opening. Finger reinforcement is continuous around each sleeve, and can include rebar hairpins 321, 322 as shown in FIG. 9, that enclose the sleeve and extend into the wall a distance that is sufficient to develop the strength of the reinforcement. This reinforcement can be balanced against the known shearing strength of the pin to provide the ductility necessary to safely withstand seismic actions.
Once a wall block is set in position and before the hoisting lines are relaxed, steel pins 350 are dropped through the aligned sleeve in each intersecting wall block as shown in FIG. 10. In the example embodiment, the steel pin is a 25 mm reinforcing steel bar and the sleeves offer a 35 mm inside diameter. Both sleeve and pin diameter can be adjusted to control tolerances or to increase the strength of the joint as desired. The resulting joint offers exceptional strength and durability. The force required to fail a joint is equal to that required to shear the pin at every finger interface, unless internal finger reinforcement is limited in order to direct the ultimate failure mode to the tensile failure of the reinforcing steel hairpins. In either case, the lateral strength of a typical joint is likely to be many times the weight of the connected wall block, and therefore much greater than the force that would be applied by even a strong earthquake.
Connection and Lifting Points
Lifting points for each wall block can be provided by using industry standard lift inserts (not shown) and precast lifting systems that match inserts cast into the block with the lifting devices. As with any precast block, lift points should be centered about the center of gravity of the block, and that position is affected by the geometry of and openings in the block. Finger wall blocks can also be provided with internal sleeves or crosses as lifting points; this detail is particularly desirable when the wall blocks are combined in a structure with the LadderBlock framing system, because it can allow all elements to be lifted with a consistent set of rigging.
The finger block wall blocks of the current invention may be constructed of cast aerated concrete, light weight concrete, normal weight concrete, or any other structural grade castable material in combination with whatever internal reinforcement is needed to provide the necessary structural characteristics for a given application.
A pair of walls is immediately stable once a joining pin has been installed, but when three or more walls connect at a joint, all of the joining members must be installed before the pin can be installed. One technique for temporarily interconnecting blocks, as already demonstrated by the LadderBlock framing system, uses steel pipes to nest within the pipe sleeves in a pair of blocks to cross a joint. Such a pipe shear connector still allows the threaded rod, or pin in this case, to be installed once the connection is complete. In lieu of this method, simple wall-to-wall braces can be installed until all walls have been placed and the pin set.
One basic structural objective in determining finger patterns is to provide at least two interior fingers at each end of each wall, and to vertically separate those fingers as much as possible within a coordinated joint. Each interior finger offers the strength of placing the steel pin in double shear, meaning that it would have to be sheared across two planes to break the joint at the finger; this doubles the shear strength by comparison to a single shear joint. Block 100c of FIG. 25 is structurally disadvantaged because it fails the objective of providing at least two interior fingers. The exterior finger 110 at the top of this wall block can be pulled away from the joint by shearing the pin across a single plane. Although that may be structurally acceptable for a given application, the general objective of providing at least two separated interior fingers can provide an exceptionally strong joint. The strength of a joint may be increased by increasing the distance between two fingers on a panel, and it is generally desirable to provide as much vertical separation as practical between at least two fingers on each panel.
Consider the work required to pull a single interior finger out of a joint 530 such as shown in FIG. 28. Two grouted keys, which provide additional shear strength over the strength of the bond between the grout and the fingers, 161 and 162 would have to fail, and then one 25 mm or larger diameter reinforcing steel bar would have to shear on two planes 510 and 520 as shown in FIG. 29. Or the concrete finger itself would have to fail, including the failure of reinforcing steel hairpins 321, 322 that wrap around the sleeve in every finger and extend back into the wall block as shown in FIG. 30. The resulting high joint strength is provided very cost effectively, and can be won without sacrificing the speed of construction that distinguishes the LadderBlock system.
DETAILED DESCRIPTION OF INVENTION--ASSEMBLY OF FINGER BLOCK WALL BLOCKS
The assembly of a finger wall system is straight-forward. Once foundations are built, the first wall block is set and temporarily braced. As each subsequent finger wall block is set in place, its pins are installed, and then subsequent interconnecting wall blocks, floor blocks, and stacked wall blocks can be assembled. Joints can then be filled to complete the construction process.
Foundations must be designed to transfer all expected loads to the soil, and the design of these systems should be based on soil capacities that are determined through a geotechnical engineering analysis. The foundation system might consist of a properly engineered grade supported slab, or it might use short finger wall blocks to serve as a foundation beam that carries a suspended first floor and the wall above as shown in FIGS. 11A and 11B. The foundation beam might be supported on footings, piers, or piles, or for low-rise structures it might bear directly on the leveled, stable soil. FIG. 11B shows a support ledge 410 on block 400 which supports floor block 420. In this example, the floor block 420 and the support ledge are dimensioned so that the groove 200 of wall block 100 rests on the continuous plinth 202 of block 400, and on a portion of the floor block 420.
The diameter and material strength of the steel pins can be adjusted to control the design strength of the joint or to control fit-up tolerances. Where the desire is for temporary construction that can be quickly dismantled, finger wall blocks can be connected with pins only and the joint positions fixed with dry wedges instead of grout. This is possible because the pinned finger connections to perpendicular or angled blocks can by themselves provide the stability required.
Joint Fixity Prior to Grouting
If necessary, temporary wedges can be driven into joints to adjust and fix the position of two wall blocks relative to one another, but the blocks can only move within the limits of the pin installation tolerance; that tolerance being provided by the diameter of the pin being slightly smaller than that of the aligned sleeves.
A few basic joint types can be combined to build virtually any configuration. These include corner joints, butt joints, tee joints, and cross joints. Each joint type utilizes fingers at the ends of wall blocks, and tee and cross joints interlace these fingers with cast receivers in the continuous wall block at the joint. In this example, a total of ten fingers from two or more wall blocks enter a given joint. For illustration, these fingers may be considered to have relative positions numbered 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 starting from the top finger position.
In a butt joint or corner joint, one block such as block 100a of FIG. 13 has five fingers oriented in positions 1, 3, 5, 7, and 9 (Pattern A) while a second block shown as block 100b in FIG. 12 has five fingers oriented in positions 2, 4, 6, 8, 10 (Pattern B). This ten finger pattern is an example of one way to construct the blocks and fingers, and other sizes and numbers of fingers could be used.
One example of a tee joint combines a Pattern B block 100b shown in FIG. 14C with a Pattern "C" block 100c having two fingers in positions 1 and 9 as shown in FIG. 15; and a Pattern "D" block 100d having three fingers in positions 3, 5, and 7 as shown in FIG. 16
One example of a cross joint as shown in FIG. 17 uses a Pattern "C" block 100c, a Pattern "D" block 100d, a block 100e with two fingers at positions 2 and 10, and a block 100f with three fingers at positions 4, 6, and 8.
A three axis joint such as shown in FIG. 17 can be made with blocks such as 100b, 100c, and 100d as shown in the tee block of FIG. 14C; or the three axis joint may be made with other finger configurations.
It should be noted that a butt joint between parallel wall blocks does not provide the stability inherent in a perpendicular or angled joint. Butt joints are suitable at ends of curtain wall blocks that are hung on a LadderBlock platform (FIG. 18), or where lateral stability is provided by pilasters 450a, 450b, 450c, and 450d or vertical tie-downs within the wall system.
FIG. 25 shows a tee joint where two blocks have been aligned with fingers at positions 2, 4, 6, 8, and 10, and block 100a with fingers at positions 1, 3, 5, 7, and 9 is aligned for insertion. FIG. 25 also shows a a tee joint where two blocks have been aligned with fingers at positions 1, 3, 5, 7, and 9, and block 100b with fingers at positions 2, 4, 6, 8, and 10 is aligned for insertion. FIG. 25 also shows a cross joint where two blocks have been aligned with fingers at positions 2, 4, 6, 8, and 10, and blocks 100d with fingers at positions 3, 5, 7, and block 100c with fingers at positions 1 and 9 are aligned for insertion.
When the fingers at the ends of two members combine to complete a five finger Pattern A or Pattern B, those patterns are described as complementary. A key concept that is demonstrated by FIG. 26 is that of complementary finger patterns such as those of blocks 100h and 100g, 100i and 100j, 100k and 100l, and 100m and 100n.
FIG. 26 shows a number of examples of complementary finger patterns, and demonstrates some of the ways in which they can be combined to connect two, three, or four members at a perpendicular joint. By simply extending the length of the fingers, the same system can also be used to combine more than four members radially about a common pin centerline such as shown in FIG. 27. It should be noted that, when more than three wall blocks create a closed joint, the spaces between fingers of one or more blocks should be cast with whatever access blockouts are needed for the intended grouting method. If a flowable grout is to be cast, theses grout access blackouts can be minimized or eliminated.
Floor Block Support
Ledges can be cast into the top of finger wall blocks to carry floor blocks 421, 422 on one or both sides of the wall as shown in FIG. 19. Where short lateral spans within a wall system mean that diaphragm forces are low, the floor blocks might be able to be dry set and left ungrouted. Where required by structural actions, the joints between floor blocks can be keyed and grouted. Top surfaces of floor blocks might be produced with a final finish, or they can be left rough to receive a concrete topping 430 that provides an additional layer of interlock between the floor and wall block systems as shown in FIG. 20.
As with the first level of construction, only the first finger wall block at each level of construction is likely to require temporary bracing. Subsequent blocks can generally gain immediate stability upon the installation of the first pinned finger joint connection. Structural actions for each assembly must be evaluated, but stacks of multiple stories are possible, with tall and narrow structures potentially requiring continuity elements such as vertical post-tensioning.
Joints can be completed in a variety of ways, but in the example embodiment the joint is backed with one or more shims 480 at each level (FIG. 21). The shims may be flat or have complementary wedges. A measured amount of grout is then placed at each level of the joint, at which time additional shims can be to drive grout to the surfaces of the joint (FIG. 22). The purpose of the joint shims is to reduce both the amount of grout and the skill required to successfully complete the joint, but joints could also be completed using dry pack or other common methods.
One example of the use of complementary finger patterns is seen at the three member 600a, 600a, 600b exploded joint shown near the center of FIG. 31 In this figure, a standard six-block set builds a two dormitory room module that includes two external fins or pilasters on the perimeter wall; without these a two room module would be just a four block set. In this example, blocks 600b and 600c have different finger configurations depending on whether pilasters are added. A six block set comprises blocks 600a, 600b, 600c, 600d, 600e, and 600h.
As shown in FIG. 32, each room in this example has a door opening 610, a window 611, and an opening 612 for a wall mounted air-conditioning unit. External fins 600h provide wall shading and obscure air conditioning units from view. It is worth noting the finger patterns for the center dividing wall 600c and external fins in each module. Fingers at these joints are high and low, and mid-level fingers have been omitted. This leaves undisturbed the reinforced concrete wall section adjacent to the window openings in the host perimeter wall. The dividing walls present a stronger five finger pattern at the corridor 600b. Such unnecessarily strong joints can provide additional layers of structural safety in an extreme event. It should also be noted that the left and right end of each corridor wall and perimeter wall offer complementary finger patterns. This allows wall blocks and two room modules to nest end-to-end and build a continuous line of spaces as shown in FIG. 32 with a very small number of unique blocks. These spaces could have exterior doors, or they could share a corridor with another mirror-image line of assembled wall blocks. Dividing walls could easily be positioned to create spaces of different sizes, and could incorporate door openings to interconnect rooms.
FIG. 33A shows an exploded view of one example of how the system can be used to build architectural features and relief on the face of an otherwise flat facade. In this example block 615a provides an extension feature, while blocks 615b and 615c permit an inset window wall block. External fins might also be tapered, or their exterior edges could be cut into geometric patterns that might transform a building into a sculpture.
Wall Block Details
Door and window openings can be precast into each block, and reinforcing steel to resist the stresses that develop around each opening is engineered in response to the calculated loads in a proposed assembly. In cases, an opening might be so large that the wall block is reduced to rigid frame consisting of a beam and two supporting columns. Such a member 620a is shown in the exploded view of FIG. 34 and in the assembled view of FIG. 35.
Where no column can be accommodated within the architectural floor plan, beams can be built of this same system as shown in FIG. 36. Unlike wall blocks that bear on their bases and not at fingers, beam blocks bear only at fingers. Beam blocks such as 622a and 622b therefore generally require some sort of temporary shoring at their free end. The shoring must be installed when the first end fingers are set on shims and pinned, and it must be left in place until the supporting wall and shims at the shored end have been installed. But in this example, the beams are also supported by the divider walls 623 and 624 near the beam midspan, so no temporary shores are required. An example of a beam extension 625 from a wall block 623 that offers a connection to a perpendicular wall is shown in FIG. 37.
Note that at the near end of both beams shown in FIG. 36, and at the far end of the right beam, supporting walls are built with receivers for only the two beam fingers 626. By contrast, the supporting wall at the far end of the left beam offers a full pattern of receivers 627. This is to also receive the three lower fingers from the wall 629 that will connect at the far side of this four-way joint in the completed assembly.
Also note that at the same four-way joint shown in FIG. 37, the top of the far side wall of block 628 is higher than the other walls at the joint. This reflects a change in floor level in the architectural plan, and is accomplished by casting transition wall blocks with finger patterns that are shifted by the appropriate dimension.
Where the offset of an architectural facade such as between blocks 630 and 631 of FIG. 38; or an interior wall such as blocks 632 and 633 is on the order of a single wall thickness, a variation of the finger joint can offer a solution. The pair of walls in FIG. 38 that point to the left each offer a finger pattern B for the forward wall, and also offer double pins and two double-width receivers to accommodate two fingers from a center wall that is inset by one wall thickness as shown in FIG. 39.
Finger Floor Block System
The ledge examples described in FIG. 11B above showed a 30 cm (12 in.) thick wall that could offer a 10 cm wide ledge 410 either side of a 10 cm keyed continuous plinth 200. This application also envisions a 20 cm (8 in.) or thinner wall that can carry floor on one or both sides and stack to build multi-story construction. The thinner walls feature full-width bearing ledges at interior bearings and half-width ledges at perimeter bearings, and they show a pattern of top of wall plinths at each pinned joint that key to the base of the wall above. Because the plinths are keyed with multiple surfaces, the plotted line density causes these elements to conveniently print as solid shaded areas in FIGS. 34-39.
It should be noted that the edges of each floor block extend horizontally to the wall centerline in concert with the locations of bearing ledges cast into each supporting wall or beam. If a floor block is thought of as wall-to-wall, then these extensions can be thought of as fingers that project from the edges of a floor block to capture bearing area on a beam or wall. Floor block edges should be cast short by an erection tolerance, and larger gaps can be cast into the slab edges between fingers. Such gaps can combine with conduit that is precast into wall blocks and placed in the floor topping thickness to build the necessary network for electrical, data, and water lines 700, 701, and 702 to be routed through a building as shown in FIG. 40. Once the voids are fully grouted and the floor blocks have received a thin composite topping 430, the wall system and the floor blocks offer geometric interlock to build a structure that is exceptionally stiff, strong, and durable, and build it with exceptional speed.
Stacking and Grouting
In this embodiment, the plinths that are presented at each level of floor blocks interlock into the base of the next layer of wall blocks above, so that multi-story stacked structures can be built. FIGS. 41 and 42 demonstrate how the wall corner configuration of FIG. 34 can stack to build two or more stories. Blocks can be erected with the thin bearing pad material at block interfaces that is common to the LadderBlock framing system; this allows fast, dry erection with a very small crew. Blocks can also be set on a cushioning layer of mortar or grout, if so desired for architectural or other purposes.
Methods for dry-packing a finger joint and keys with grout after construction have been described previously. Joints could also be locked by attaching simple forms at the joints and casting them solid with a flowable grout. If flowable grout is used, shear keys at the bottom surface of each finger should be formed with a detail that evacuates air bubbles and ensures that the key fills with grout. The engineer can manipulate the joint filler material strength and elasticity to safely provide the overall strength, stiffness, and ductility that is required to safely resist a strong earthquake or other severe loading. The hardness of the joint filler material might also be engineered as required to enable disassembly without damage to the wall blocks.
Tie Down Options
In assemblies that are low-rise and not subjected to large earthquake forces, simple stacks of wall blocks with keyed interlock across a 25 mm simple rebar pin at each joint may be structurally adequate. In taller structures that are subjected to large lateral or overturning forces, the rebar pin at any joint can easily be replaced with a high-strength threaded post-tensioning bar such as that produced by Dywidag Systems International. Such a pin enables each level of grouted joint to be post-tensioned down to the supporting foundation or to the level of structure below, so that very tall structures can be built with economy and speed.
DETAILED DESCRIPTION OF INVENTION--FINGER WALL SYSTEM
The LadderBlock finger wall system offers a number of options in joint treatment, in structural design, in architectural finish and layout, and in the end use of the product.
Grout and Mortar Options
Grout strength can match that of the wall, or joints can be filled with a lower strength mortar or flexible filler that facilitates disassembly. Joints might also be filled with ductile cement concrete mixes that have been recently developed by others; such a joint treatment can provide an energy absorbing mechanism that can improve performance in structures that are subjected to large earthquake forces.
A variety of structural options can be employed in designing with the finger wall system. The system can be used to add pilasters 450 to otherwise flat walls as shown in FIG. 23, and structures of any plan may be formed of a series of perpendicular or angled walls such as shown by structure 500 in FIG. 24. Wall blocks can be built with openings as required to satisfy architectural demands, and a finger wall block with a large opening essentially becomes an open rigid frame that still utilizes the advantages of finger joint construction. Multi-story structures are possible, and finger wall systems can be load-bearing elements or curtain walls that are hung on a supporting structure. Casting material and internal reinforcement can be manipulated to suit the structural requirements of a given application, and the engineer can incorporate post-tensioning systems or conventional structural elements within a finger wall structure.
Although the example embodiment shows flat wall blocks to avoid distracting attention from key features of the system, it should be clear that textured architectural wall blocks can be produced with relative ease. Within the weight and dimensional limits necessary for transportation and handling, finger wall blocks can be produced in any desired length, thickness, and height, and with the necessary door and window openings to build any desired plan geometry. Wall blocks can be produced using form liners, integral pigments, reveals, surface treatments, and veneers to produce any desired architectural effect.
It should be noted that joints do not necessarily have to be perpendicular, angled joints of this construction can be made by adjusting end form geometry to the angle desired.
Finger wall blocks can be used to quickly, safely, and cost-effectively build temporary or permanent construction for any use. They can build free-standing perimeter wall systems or be incorporated into structures and buildings intended for any use, either as a strand-alone load bearing wall system or as a curtain wall in combination with a LadderBlock platform or a conventional structure.
The LadderBlock finger wall system offers distinct advantages to the designers, builders, and end users of a structure. These advantages can be characterized by the potential cost savings, speed of construction, flexibility, and environmental responsibility embodied in the system.
Cost of Construction
This system can dramatically reduce the cost of construction by allowing all but a small fraction of the construction to be accomplished in the safety and convenience of working at ground level, and by standardizing joint construction so that wall blocks of any length can be built with precision and ease. By developing standardized lengths and block configurations to maximize repetition in the manufacturing and building processes, construction economy can be increased further still.
Speed of Construction
As with the LadderBlock framing system, the finger wall system offers unprecedented speed of construction with a small crew by minimizing the need for temporary shoring and by eliminating the need for welding to occur before hoisting lines can be relaxed. The immediate stability offered by the system means that projects can be built faster and with greater safety.
Although the greatest advantages of this system can be gained through the standardization of wall blocks, the ease with which a finger wall block can be formed to any desired length within a continuous form bed means that even custom architectural projects can enjoy the benefits of this system.
Structural Redundancy and Durability
Even to the untrained eye, it is somewhat obvious that a series of reinforced precast walls that interlock across finger jointed corners and intersections, and that are pinned with large diameter high strength steel rods that pass through those joints, will build a structure that is exceptionally strong and stable. The sheer number of structural material failures that must occur for one of these joints to be pulled apart means that the chance of a structure experiencing a load that is large enough to fail a joint is exceptionally small. In a 3 m tall wall of this construction, the steel pin would have to be sheared across 9 separate planes, or the 5 reinforced concrete fingers at the end of one block would have to fail. At a joint in a given building, the force required to initiate either of these failures is likely to be many times larger than the worst-case force predicted by standard building Codes.
Because this system can utilize all of the advantages of available technologies in form lining, coloring, and texturing of concrete faces, virtually any grade of architectural end product can be produced to form any layout and vertical configuration. The system offers an opportunity for maximum cost effectiveness through a standard kit of parts, but it eliminates architectural constraint by offering more costly but still efficient block sets that can be made to any specification.
Building construction and demolition debris account for a surprisingly large percentage of the materials that are sent to landfills. The disposal of all that debris presents obvious environmental hazards, and represents a pitiful waste of resources. The LadderBlock finger wall system addresses these problems directly by offering a way for durable construction to be disassembled and reused, and more importantly by offering an economical way to build structures of such high quality that their demolition would never be considered, much less required.
Basic Building Block--Alternative Uses
The LadderBlock framing, wall, and floor systems can be used independently or in conjunction with one another to build virtually any structure for any purpose. The LadderBlock technology for joining blocks of precision construction can be applied to the construction of building and bridge structures, but it can also build other types of structures while offering all of the same advantages.
Consider a single example Wall Block as shown in FIG. 43, 5 meters wide, and then consider the infinite number of ways in which it might be combined; a few simple example profiles 591, 592, 593, 594 are shown in FIG. 44. Turning an angle sharper than 90 degrees requires that the fingers simply be extended or that the conflicting surfaces be sculpted to avoid conflict. This can be accomplished with a simple form insert that offers the desired geometry. These building blocks can be used to build a pool, an elevator shaft, a silo, or a free-form structure. These are examples that are limited to a single width of building block. Clearly, the system is not thus limited. The system easily expands with the imagination of the design professional. Blocks of this system can also build a pedestal support 640 for an elevated structure as shown in FIG. 45, or larger-than-life sculpture.
Patent applications by David W. Powell, Austin, TX US
Patent applications in class Barrier of hingedly connected sections
Patent applications in all subclasses Barrier of hingedly connected sections