Patent Application
20160362867
The present invention relates generally to the building arts, and more particularly to the means and methods of constructing large dimensioned monolithic composite concrete and steel buildings and structures underwater and on dry land.
The present invention creates a new advance beyond the state of the art shown in U.S. Pat. No. 5,860,262 to Frank K. Johnson (“the '262 patent”), the disclosure which is incorporated herein by reference.
Corrosion plagues all reinforced concrete structures exposed to the elements after only a few years of service reducing the load bearing capacity of a structure and imposing heavy economic burdens on the community in order to maintain them in a safe and functionally operational condition.
Another, even more costly drawback stems from the manner in which reinforced concrete facilities are constructed. A temporary wood-sheathed structure, called formwork must be fabricated on site, erected, braced, shored and tied together in order to support, contain and shape wet concrete fill for a relatively small section of the structure being built. After casting, this formwork structure must remain in place for a period of time while the wet concrete cures before being removed, cleaned, repaired and then re-erected to cast another section. These labor intensive, time consuming tasks are repeated over and over again for each incremental unit of the structure until the last cubic yard of concrete has been cast.
Vertical formwork for constructing walls must be braced and tie rods fastened to the forms to prevent them from separating when the wet concrete fill is cast into the void space. Formwork supporting horizontal slabs must be shored from underneath and the shores and formwork left in place until the concrete has gained sufficient strength to support itself before they can be removed and reused to cast another incremental section of deck or floor slab.
Concurrently with erection of the formwork, another labor-intensive, time consuming and even more costly task is taking place: rebar installation. Typically, for walls, vertical rods are installed first, one at a time. One by one, horizontal rods are then attached to the installed verticals with wires hand twisted by workers supported on the steel cage they are erecting.
The industry has made strides in reducing costs of formwork and rebar installation when constructing high rise commercial and residential buildings. Common practice in the industry is to design a building's structural steel framework and shallow reinforced concrete floor slabs as a composite structure. In such a building stay-in-place corrugated steel sheets are used to support wet concrete fill between structural members. Horizontal rebar is placed as shop-welded mats, not one at a time.
The finished concrete slab is supported on the top flanges of the wide flange structural steel members. Studs welded to the top flange protrude into the concrete slab to make the two different building materials act as a single composite structure. Composite design results in savings by requiring fewer columns, beams and connections, producing longer spans and larger rooms in buildings, and providing more flexible, and saleable floor plans. The downside of this type of construction is that the steel beams supporting composite floor slabs are exposed and must be fireproofed, another labor intensive, time consuming and costly activity.
The '262 patent discloses a panelized mold apparatus for containing, shaping and permanently encasing monolithically cast reinforced concrete walls, footings, beams and floor slabs using interlocking panel assemblies to form foundation, cavity wall and roof deck void spaces.
The perforated steel sheets used to attach parallel wall assemblies together and prevent the two sides of the cavity walls from separating during the casting process are not considered as reinforcing steel when calculating the tensile requirements for the structure. Nor are the perforated steel sheets in the footings and truss assemblies considered as reinforcement.
The '262 patent does not disclose how horizontal and vertical reinforcing steel rods are to be installed within the void spaces when the perforated sheet steel attachments are spaced at such close intervals. Nor does the patent disclose how vertical wall assemblies are to be supported against hydrostatic loads when distance between the inside and outside wall assemblies forming the void space is excessive as in the case of large dimensioned pile caps, deep deck, floor and roof slabs, foundations and piers supported on piles; nor does the '262 patent disclose how the horizontal platform assemblies are to be supported to carry gravity loads associated with casting reinforced concrete slabs over very long spans without intermediary supports or shoring.
The '262 patent does not disclose how the panelized assemblies are to be erected and rebars installed when the work site is under water. Typically, the work site must be made dry in order for the workers to erect formwork and install rebar. Making a work site dry in the middle of a body of water requires construction of a water tight enclosure, dewatering and other tasks prior to commencing concrete work, tasks that add considerable time and cost to a construction project.
It is the object of the present invention to provide a means for structurally supporting vertical and horizontal stay-in-place panelized encasement assemblies of a modular steel-framed construction mold apparatus by integrally attaching the panelized encasement assemblies to a structural steel grillage, said grillage being capable of supporting said assemblies vertically to great depths and heights, and horizontally over very long spans without recourse to external supports.
It is also an object of the present invention for the steel grillage to provide tensile strength to the permanently encased monolithic composite concrete and steel structure, thereby eliminating the necessity, and costs of installing rebar at the work site.
It is another object of the present invention to integrally attach the panelized encasement assemblies of the mold apparatus directly to structural members of the steel grillage so the two systems act as a composite unit.
It is yet another objective of the present invention to increase productivity at the construction site by pre-assembling the structural steel grillage into modular units off-site under controlled conditions.
Another object of the present invention is to pre-assemble encasement panels and connectors off-site and attach them to the grillage to form a modular unit of a steel-framed construction mold apparatus, which can be transported to the site ready for immediate installation, greatly reducing construction activity at the work site and making underwater construction of composite concrete and steel structures both practical and economical.
Another object of the present invention is to reduce the costs and facilitate construction of permanently encased monolithic composite concrete and steel structures underwater by eliminating the need for constructing temporary watertight structures typically used to create a dry work area in a submerged work site.
The above objects are met in the present invention by panelized encasement assemblies integrally attached to vertical and horizontal members of a structural steel grillage that can be used to advantage for underwater construction of large monolithically cast concrete and steel civil engineering works that include bridge abutments, piers, decks and superstructures, piles and pile caps, foundation, floor and roof slabs, shear walls, core walls, retaining walls and footings, deep foundation walls, seawalls, box culverts, flood protection cofferdams, off-shore barrier reefs and coastal islands. While steel is referred to herein it will be understood that for particular applications steel sheets, I-beams, angles, and channels and other shapes used as purlins, girts, columns, connectors, girders and bollards can be made of other metals and/or be substituted with fiber reinforced composites where fibrous reinforcements are metal, carbon or glass and the matrix is plastic, metal or carbon.
Additionally the present invention can be used to advantage in providing strength to hold panelized encasement assemblies in place before and during the casting process, and after casting providing tensile strength and rigidity to composite structures without recourse to conventional steel reinforcement rods typically employed for this purpose,
Additionally, the present invention in any of the cited or other such dry and applications can be used with reinforcing rods or the like in the construction of permanently encased monolithic composite concrete and steel structures to provide additional tensile or bending strength, as specified by the design engineer.
The construction mold for forming, casting, and encasing the above composite concrete and steel structures is comprised of foundation/footing, cavity wall and roof deck encasement sub-assemblies joined together to act as a single structural unit that forms structured void spaces for receiving wet concrete in situ underwater and on dry land.
The panelized encasement assembly component of the modular steel-frame construction mold apparatus is comprised of interlocking encasement panels and connectors that are integrally attached to a corresponding structural steel grillage component. T-shaped tension keys protruding from the end was of encasement panels matingly interlock with keyways formed in the body of connector brackets. The reverse is also feasible, i.e. keys on the brackets and keyways formed on the end walls. In addition, connector brackets are the means of removeably and integrally attaching the encasement assemblies to the structural steel grillage.
Concrete is cast into the foundation, cavity wall and roof deck void spaces formed by the modular steel-framed construction mold apparatus in a substantially continuous fashion to produce a monolithic permanently encased composite concrete and steel structure.
The encasement assemblies remain in place after the wet concrete has been cast into them, protecting the inner and outer surfaces of the composite concrete and steel foundations, walls and columns, and the under surface of composite concrete and steel floor and roof slabs. The structural steel grillage becomes permanently embedded in the wet concrete during the casting process and provides tensile strength complementing the compressive strength of concrete in the resulting structure.
The advantage of the present invention is that the structural steel I-beams, angles, channels and other standard sections making up the grillage component provide a strong and rigid means of supporting the encasement assemblies during fabrication, shipping, handling, installation and casting. Another advantage is the structural steel grillage component facilitates construction of composite concrete and steel structures underwater. Yet another advantage the structural steel grillage provides is to enable forming and casting of very wide horizontal structures such as piers and pile caps, and very long unsupported horizontal spans such as bridges, box culverts, and box girders. The structural steel grillage provides a stronger and more practical means of supporting encasement assemblies than the perforated steel tie sheets called for in the '262 patent, eliminates the need for installing reinforcing steel at the work site, and makes construction of composite concrete and steel structures simpler, safer, and more economical, both on dry land and underwater.
Other objects, features and advantages will be apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the accompanying drawings in which:
Referring now to the drawings, in which like numerals indicate like elements throughout several views and pointing out that all protruding interlocking elements integrally attached to various encasement components are configured to slidably interlock.
Corresponding housings formed within the bodies of various encasement elements are likewise identical in configuration and size and capable of slidably interlocking and engaging all protruding elements.
Each column 41 is supported by and integrally attached to a steel pedestal 47 comprised of two bollards 471 and integrally joined at the top by cross beam 472. Roof girder, joist or truss member 42 integrally joins the top portion of two opposing columns 41 to form a rigid bent. Base beam 43 integrally joins the pedestals 47 of two opposing columns 41. A plurality of evenly spaced horizontal beams or girts 441 are integrally attached to the outside flange of columns 41 in each row. A plurality of girts 442 are likewise attached to the inside flange of columns 41 in each row spaced opposite to the outside girts 441. A plurality of roof beams or purlins 452 are integrally attached to the lower flange of the roof girders 42. Steel brackets 46, integrally attached to grillage girts 44 and purlins 45, project away from the grillage into the void space 20, integrally attach to corresponding encasement brackets projecting inward to void space 20 from the encasement component of the modular mold unit shown in
The length of a steel-framed construction mold apparatus modular unit is defined by the horizontal girts 44 attached to the grillage columns 41 and purlins 45 attached to the roof girders 42. Grillage columns 41 define the height of the modular unit, and roof girders 42 and base beams 43 define its width. The structural steel elements comprising the grillage component 40 of the steel-framed construction mold apparatus modular unit, including columns 41, base beams 43, girts 44, purlins 45, bollards 471 and cross beams 472 may be sized and dimensioned to the design engineers specifications to meet the loading and functional requirements of the resulting composite concrete and steel structure, existing site considerations, availability of equipment and resources at the work site, and other variable parameters associated with usage and construction activities.
The foundation encasement sub-assembly 31 which defines and forms the foundation slab void space 21 is comprised of a plurality of encasement panels 1 integrally connected together to form a sold wall by panel connector brackets 2. The pan& connector brackets 2 integrally attach to corresponding steel brackets 46 attached to the structural members 44, 45 of the grillage component by bolts and nuts or other such mechanical means [not shown).
The edge of one encasement panel 1 is integrally connected to the edge of a second encasement panel 1 as described later along their longitudinal axes by slidably interlocking t-shaped tongues or keys 121 extending outward from end wall 12 of the panel into mating keyways 203 formed in the body 202 of panel connector brackets 2.
The height of the vertically aligned panels 1 and connectors 2 comprising the foundation encasement sub-assembly is specified by the design engineer.
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The outer side wall 441 is vertically aligned in the preferred embodiment to facilitate joining the modular construction unit to a second previously installed modular construction unit at the work site and forming the outer wall 331 of the roof deck encasement sub-assembly 33.
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T-shaped tensile keys or tongues 11 protruding from the end walls 12 of the panel are situated in the wall section above the panel cross-section centerline 121 to fully resist the tensile forces imposed upon the panel during the casting process. The section of the end wall of the panel below the centerline of the panel section 122 is thickened to fully resist compression forces imposed during casting. Interior 131 and exterior 141 panel walls for the first two cell widths in from the ends of the panel are thicker than the interior 132 and exterior 142 panel walls in the center portion of the panel in order to resist bending without breaking during casting.
T-shaped tensile keys 11 protruding from the end walls 12 of the polymer end connector are situated in the wall section above the panel centerline 121 to fully resist the tensile forces imposed upon the panel during the casting process. The section of said end wall below the centerline 122 is thickened to fully resist compression forces imposed during casting.
The section of the connector body below the centerline 305 is reduced in outside dimension but the walls of the hollow body 304 (hollow body are increased in thickness to resist compression forces.
Outside corner connector bracket 5 is a hollow-core reinforced polymer pultruded or extruded structural element consisting of two t-shaped grooves or keyways 505 formed at 90° to one another into the square-shaped hollow body 503 of the connector. Keyways 505 are configured to receive t-shaped tension keys 11 protruding form the edges of the two encasement panels 1 interlocked and integrally connected by the connector. The section of the walls of the hollow body opposite the keyways 506 is thickened to resist compression forces.
A fabricating under controlled conditions structural steel grillage components for a modular custom-engineered steel-framed construction mold apparatus;
B integrally connecting encasement panels and connectors under controlled conditions into custom-engineered panelized encasement components corresponding to the steel grillage components fabricated in step A;
C integrally attaching said panelized encasement assembly components produced in step B to said steel grillage component fabricated in step A under controlled conditions to create modular steel-framed modular construction mold units:
D batching and mixing concrete fill under controlled conditions;
and construction site steps of:
1 site preparation work consisting of surveying, dredging out unsuitable material and backfilling stones or other suitable base materials;
2 transporting modular construction unit produced in step C site and installing said modular units by integrally joining grillage and encasement components of said unit to corresponding components of previously installed units to form a larger segment of the underwater steel-framed construction mold apparatus.
3 Placing stones or other suitable materials to support the concrete foundation slab;
4 Pumping and casting concrete fill into the structured void spaces of said modular mold apparatus to produce a permanently encased monolithic composite concrete and steel structure.
5 Finishing work which consists primarily of screeding concrete surfaces.
Steps A, B, C, and D, take place off site under controlled conditions. Steps 1, 2, 3, 4 and 5 take place on site underwater. The structural steel grillage component of the mold apparatus becomes fully embedded in the cast concrete. The panelized encasement component used to form and contain the wet concrete fill stays in place after the casting process is completed permanently protecting and insulating the submerged monolithic composite concrete and steel structure.
A similar reinforced concrete structure constructed underwater using conventional designs, materials, means and methods would involve ten or more on construction site work steps to complete, would take many months longer to construct, and cost many times more than the preferred methodology.
The present invention obviates the need to:
As a consequence, said mold apparatus facilitates and accelerates concrete work under water, making underwater concrete construction a practical and economically viable alternative for creating durable and reliable structures that prevent flooding and coastal erosion, and other applications heretofore not considered viable due to cost considerations.
For review drawing reference numerals and items referenced are repeated here:
Structured Void Spaces 20
Panelized Encasement Component 30
Structural Steel Grillage Component 40
Site Preparation 61
Module Fabrication & Mold Installation 62
Concrete Work 63
It will now be apparent to those skilled in the art that other embodiments, improvements, details and uses can be made consistent with the letter and spirit of the foregoing disclosure and within the scope of this patent, which is limited only by the following claims, construed in accordance with the patent law, including the doctrine of equivalents.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12503414 | Jul 2009 | US |
| Child | 15207162 | US |
