Patent Description:
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

The wind turbine tower is generally constructed of steel tubes, pre-fabricated concrete sections, or combinations thereof. Further, the tubes and/or concrete sections are typically formed off-site, shipped on-site, and then arranged together to erect the tower. For example, one manufacturing method includes forming pre-cast concrete rings, shipping the rings to the site, arranging the rings atop one another, and then securing the rings together. As wind turbines continue to grow in size, however, conventional manufacturing methods are limited by transportation regulations that prohibit shipping of tower sections having a diameter greater than about four to five meters. Thus, certain tower manufacturing methods include forming a plurality of arc segments and securing the segments together on site to form the diameter of the tower, e.g., via bolting and/or welding. Such methods, however, require extensive labor and can be time-consuming.

In view of the foregoing, the art is continually seeking improved methods for manufacturing wind turbine towers. For example, more recently, progress has been made in the construction of wind turbine towers, at least in part, using additive printing techniques. Such methods allow for the tower structures to be erected on site and also allow the structures to be built to taller heights. Examples of such 3d printing possibilities according to the state of the art are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

However, during construction of existing towers, it may be desirable to include a tower portion having an access opening, such as a pre-fabricated door or a section of a foundation, in the structure. However, additional reinforcement must also be included around such access opening as the structure is being built. In addition, reinforcement placement can be difficult to automate since the reinforcements (e.g., rebar, tension cables, etc.) must be placed in various orientations around the access opening to properly reinforce the access opening.

Accordingly, the present disclosure is directed to an additively-manufactured structure having a reinforced access opening that addresses the aforementioned issues.

Aspects and advantages of the invention are set forth in the appended claims.

In one aspect, the present disclosure is directed to a method of additively-manufacturing a structure having a reinforced access opening. The method includes printing, via an additive printing device having at least one printer head, a portion of the structure adjacent to a support surface. The portion of the structure is printed of a cementitious material, and the printed portion of the structure defines an access opening. Moreover, the method includes providing a void of the cementitious material at a top boundary of the access opening, placing one or more reinforcement members in the void such that the one or more reinforcement members extend across the void, and continuing to print the printed portion of the structure around the void to build up the structure. Thus, the method also includes backfilling the void with a backfill material to incorporate the one or more reinforcement members within the void into the printed portion of the structure.

In another aspect, the present disclosure is directed to structure including a support surface and a printed portion formed from a cementitious material. The printed portion of the structure is adjacent to the support surface and comprises a reinforced access opening, which is achieved via a backfilled void. In particular, the printed portion comprises a pre-fabricated door assembly to define, at least in part, the access opening. The reinforced access opening is achieved via a backfilled void at a top boundary of the access opening. The backfilled void includes backfilled cementitious material and one or more reinforcement members embedded within the backfilled cementitious material and extending across the backfilled void such that the one or more reinforcement members are incorporated into the printed portion of the structure. As such, the structure includes a reinforced access opening and a backfilled void.

In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention as set forth in the appended claims.

Generally, the present disclosure is directed to an additively-manufactured structure, such as a tower structure or a tower segment (with emphasis on the section of a tower segment adjacent to an interface between two or more tower segments, for example), having a reinforced access opening(s) and methods for manufacturing same using automated deposition of cementitious materials and/or other construction materials via technologies such as additive manufacturing, <NUM>-D printing, spray deposition, extrusion additive manufacturing, concrete printing, automated fiber deposition, as well as other techniques that utilize computer numerical control and multiple degrees of freedom to deposit material. More specifically, methods of the present disclosure include using an automated additive printing device to print a tower structure, while also incorporating a pre-fabricated component (such as a door frame), or while using formwork or a cast component, to yield the reinforced access opening for the printed tower structure.

For example, in an embodiment, the tower structures of the present disclosure may include a pre-fabricated door assembly or a pre-fabricated foundation assembly and a backfilled void. The pre-fabricated component is constructed of a composite material reinforced with a plurality of reinforcement members, with portions of the reinforcement members protruding from the composite material. In particular, the reinforcement members around the pre-fabricated component are purposely left extending beyond the component and into the surrounding printed or print-poured section of the broader tower structure being built. Similarly, the backfilled void is situated adjacent to the pre-fabricated component and includes backfill material reinforced with one or more reinforcement members embedded within the backfill material and extending across the backfilled void and protruding therefrom. The backfill material may include any suitable workable paste that is configured to bind together after curing to form a structure. Suitable cementitious materials include, for example, concrete, pitch resin, asphalt, geopolymers, polymers, cement, mortar, cementitious compositions, or similar materials or compositions.

Accordingly, in an embodiment, the additive printing device is configured to: (<NUM>) print cementitious material to build up the tower structure layer by layer around the pre-fabricated component or the formwork; (<NUM>) in doing so, leaving a void to be backfilled; and (<NUM>) then subsequently backfilling the void after the reinforcement member(s) are placed into/through the void. As such, the portions of the reinforcement members protruding from the composite material, and the portions of the reinforcement members extending across the backfilled void reinforce the cementitious material around the access opening. Alternatively, the pre-fabricated component, for example, a pre-fabricated door assembly, or formwork may be positioned and installed about the access opening after at least a portion of the void is backfilled.

In another embodiment, manufacturing the tower structure may include positioning formwork to define the access opening and/or the backfilled void before, during, or after printing the portion of the tower structure around the access opening and/or the void is constructed, built up, or printed. As described herein, the formwork may include temporary or permanent molds into which the cementitious material and/or the backfill material is deposited. Further, the formwork may be supported by falsework. The falsework may include temporary structures commonly used in construction to support permanent structure(s) until construction has sufficiently progressed for the permanent structure(s) to be supported/self-supporting. In particular, in certain embodiments, pillars act as falsework to support stackable formwork to facilitate near continuous production of the backfilled void. In other embodiments, the formwork may be printed and take the form of a cast or shell for receiving cementitious material and/or backfill material.

For example, in an embodiment, manufacturing the tower structure may include positioning a cast-like printed formwork (herein referred to as a "cast component") to define the access opening and/or the backfilled void before, during, or after printing the portion of the tower structure around the access opening and/or the void. The cast component may be left permanently embedded in the printed portion of the tower structure as the tower structure is built up, or the cast component may be printed in place, used, and removed from the printed portion of the tower structure as the tower structure is built up. In particular, in certain embodiments, the cast component includes a different cementitious material composition than the composition of the cementitious material to be introduced into the cast component or to be used for printing the remainder of the tower structure.

As used herein, the term "cast component" generally refers to a type of pre-fabricated component, and the term "pre-fabricated component" generally refers, but is not limited to: (<NUM>) cast components that are printed in situ during printing of the tower structure; (<NUM>) cast components that are pre-printed separately from the tower structure; (<NUM>) pre-fabricated door assemblies and pre-fabricated foundation assemblies; and (<NUM>) equivalent structures described in further detail herein.

Thus, the methods described herein provide many advantages not present in the prior art. For example, the additively-manufactured structures described herein may include the necessary reinforcement to strengthen the overall structure in the region of the access opening, thereby simplifying the process of reinforcement placement (which is relatively complex around the access opening). Thus, the overall load bearing capabilities of the additively-manufactured structure at and about the access opening can be improved. Moreover, the present disclosure may permit on-site printing of structures having any desirable size, thereby enabling the construction of large tower structures and wind turbines. Accordingly, the structures manufactured using methods of the present disclosure may be formed without requiring a tall crane. The methods of the present disclosure may also increase design flexibility, eliminate overall size restrictions, and permit the formation of structures having any desirable profile and cross-sectional shape. The additive printing device may also utilize any suitable number of variable width printer heads to decrease manufacturing time and/or to create gaps or voids during continuous printing, for example. Moreover, the present disclosure is configured to minimize cold joint formation and provide solutions to minimize the effects and influences of cold joints where such joints unavoidably might develop.

Referring now to the drawings, <FIG> illustrates a perspective view of one embodiment of an additively-manufactured structure of the present disclosure, specifically, a wind turbine <NUM>. As shown, the wind turbine <NUM> includes a tower <NUM> extending from a foundation <NUM> or support surface with an access opening <NUM> and a nacelle <NUM> mounted atop the tower <NUM>. A plurality of rotor blades <NUM> are mounted to a rotor hub <NUM>, which is in turn connected to a main flange that turns a main rotor shaft. The wind turbine power generation and control components (not shown) are typically housed within the nacelle <NUM>. Moreover, as shown, the tower <NUM> may also include a base portion <NUM> below the access opening <NUM>. In an embodiment, the base portion <NUM> of the tower <NUM> below the access opening <NUM> may be manufactured differently than the portion <NUM> of the tower structure <NUM> surrounding and/or including the access opening <NUM>. Similarly, the portion <NUM> of the tower structure <NUM> above the access opening may be manufactured differently than the base portion <NUM> and/or the portion <NUM>.

The view of <FIG> is provided for illustrative purposes only to place the present invention in an exemplary field of use. It should be appreciated that the invention is not limited to any particular type of wind turbine configuration. In addition, the present invention is not limited to use with wind turbine towers but may be utilized in any application having concrete constructions and/or tall tower structures in addition to wind towers, including for example homes, bridges, tall towers, building construction, and other aspects of the concrete industry. Further, the methods described herein may also apply to manufacturing any similar structure that benefits from the advantages described herein.

Referring now to <FIG>, the tower structure <NUM> of the wind turbine <NUM> of <FIG> is described in more detail according to an embodiment of the present disclosure. Specifically, <FIG> illustrates a partial, cross-sectional view of one embodiment of the tower structure <NUM> of the wind turbine <NUM> according to the present disclosure. As shown, the tower structure <NUM> defines a generally circumferential tower wall <NUM> having an outer surface <NUM> and an inner surface <NUM>. Further, as shown, the circumferential tower wall <NUM> generally defines a hollow interior <NUM> that is commonly used to house various turbine components (e.g., a power converter, transformer, etc.). In addition, as will be described in more detail below, the tower structure <NUM> is formed using additive manufacturing.

Moreover, as shown, the tower structure <NUM> is formed of one or more cementitious materials <NUM> that is reinforced with one or more reinforcement members <NUM> (<FIG>), such as elongated cables or wires, helical cables or wires, reinforcing bars (also referred to as rebar), mesh reinforcing fibers (metallic or polymeric), reinforcing metallic rings (circular, oval, spiral and others as may be relevant), and/or couplings. According to an embodiment, the cementitious material <NUM> may be provided through any suitable supply system <NUM> (see, e.g., <FIG>). Further, as shown in the generalized simplified illustration of <FIG>, the reinforcement members <NUM> may be embedded in the cementitious material <NUM> during the printing process, as described in more detail below. As used herein, the cementitious materials <NUM> may include any suitable workable paste that is configured to bind together after curing to form a structure. Suitable cementitious materials include, for example, concrete, pitch resin, asphalt, geopolymers, polymers, cement, mortar, cementitious compositions, or similar materials or compositions.

According to an embodiment of the present disclosure, an adhesive material (not shown), a cold joint primer (not shown), and/or steel/metal/alloy/composite frame(s) or end cap(s) in the form of C-shaped frames, for example, (not shown) may also be provided between one or more of the cementitious materials <NUM> and the foundation <NUM>, the cementitious material <NUM> and reinforcement members <NUM>, or multiple layers of the cementitious material <NUM> and reinforcement members <NUM>. Thus, these materials may further supplement interlayer bonding between materials, facilitate integration or use of pre-fabricated components or formwork, or simply provide aesthetic benefits by capping off the rough edges of an additively-manufactured wall of cementitious material <NUM> in a tower structure <NUM>, for example.

The adhesive material described herein may include, for example, cementitious material such as mortar, polymeric materials, and/or admixtures of cementitious material and polymeric material. Adhesive formulations that include cementitious material are referred to herein as "cementitious mortar. " Cementitious mortar may include any cementitious material, which may be combined with fine aggregate. Cementitious mortar made using Portland cement and fine aggregate is sometimes referred to as "Portland cement mortar," or "OPC. " Adhesive formulations that include an admixture of cementitious material and polymeric material are referred to herein as "polymeric mortar. " Any cementitious material may be included in an admixture with a polymeric material, and optionally, fine aggregate. Adhesive formulations that include a polymeric material are referred to herein as "polymeric adhesive.

Exemplary polymeric materials that may be utilized in an adhesive formulation include may include any thermoplastic or thermosetting polymeric material, such as acrylic resins, polyepoxides, vinyl polymers (e.g., polyvinyl acetate (PVA), ethylene-vinyl acetate (EVA)), styrenes (e.g., styrene butadine), as well as copolymers or terpolymers thereof. Characteristics of exemplary polymeric materials are described in ASTM C1059 / C1059M-<NUM>, Standard Specification for Latex Agents for Bonding Fresh to Hardened Concrete.

Referring now generally to <FIG>, an additive printing device <NUM> is described according to an embodiment of the present disclosure. Notably, all or part of tower structure <NUM> may be printed, layer-by-layer, using the additive printing device <NUM>, which may use any suitable mechanisms for depositing layers of additive material, such as concrete, to form tower structure <NUM>. Additive manufacturing, as used herein, is generally understood to encompass processes used to synthesize three-dimensional objects in which successive layers of material are formed under computer control to create the objects. As such, objects of almost any size and/or shape can be produced from digital model data. It should further be understood that the additive manufacturing methods of the present disclosure may encompass three degrees of freedom, as well as more than three degrees of freedom such that the printing techniques are not limited to printing stacked two-dimensional layers but are also capable of printing curved and/or irregular shapes.

It should be further understood that the additive printing device <NUM> described herein generally refers to any suitable additive printing device <NUM> having one or more nozzles for depositing material (such as the cementitious material <NUM> or the backfill material which is not shown) onto a surface that is automatically controlled by a controller to form an object programmed within the computer (such as a CAD file). More specifically, as shown in <FIG> and described below, the additive printing device <NUM> includes one or more printer heads <NUM> having any suitable number of nozzles <NUM> and being independently movable to simultaneously print layers of the tower structure <NUM>.

Referring still to <FIG>, the additive printing device <NUM> is described in more detail according to an embodiment of the present disclosure. As illustrated, the additive printing device <NUM> may include a vertical support structure <NUM> which is generally configured for suspending one or more of the printer heads <NUM> above tower structure <NUM> during the printing process. In this regard, the vertical support structure <NUM> may extend from the ground or from foundation <NUM> upwards substantially along a vertical direction V to a position at least partially above a top <NUM> of the tower structure <NUM> (e.g., and also above foundation <NUM> before the first layer is printed).

As illustrated, the vertical support structure <NUM> may include a plurality of support towers <NUM> and one or more gantry beams <NUM> that extend between at least two of the support towers <NUM>. Although two support towers <NUM> and a single gantry beam <NUM> are illustrated in the <FIG>, it should be appreciated that any suitable number and position of support towers <NUM> may be used according to alternative embodiments. In addition, the support towers <NUM> and the gantry beams <NUM> are illustrated as being truss-like structures (e.g., similar to a tower crane), but could be formed in any other suitable manner or have any other configuration according to alternative embodiments.

In addition, although the vertical support structure <NUM> is illustrated as being positioned on the outside of the tower structure <NUM>, it should be appreciated that according to alternative embodiments, the vertical support structure <NUM> may be positioned inside the tower structure <NUM>. According to still other embodiments, the vertical support structure <NUM> may include the support towers <NUM> positioned both inside and outside of the tower structure <NUM>. In addition, the additive printing device <NUM> may be suspended from the vertical support structure <NUM> using any other suitable system or mechanism.

Notably, during the additive printing process, the top <NUM> of tower structure <NUM> is built layer-by-layer, rising along the vertical direction V. Therefore, the vertical support structure <NUM> may be an expandable support structure which may be raised along with the height of tower structure <NUM>. In this regard, the vertical support structure <NUM> may be formed from a plurality of stacked segments <NUM> which are positioned adjacent each other along the vertical direction V and joined to form the rigid vertical support structure <NUM>. Thus, when the tower structure <NUM> approaches the top <NUM> of the vertical support structure <NUM>, additional segments <NUM> may be added to stacked segments <NUM> to raise the overall height of vertical support structure <NUM>.

Referring specifically to <FIG>, additional segments <NUM> may be combined with stacked segments <NUM> to raise the vertical support structure <NUM> using a jacking system <NUM>. In general, as shown, the jacking system <NUM> may be positioned proximate foundation <NUM> and is configured for raising the vertical support structure <NUM> (e.g., including the stacked segments <NUM> and the gantry beams <NUM>) and inserting additional segments <NUM>. Specifically, a separate jacking system <NUM> may be positioned at a bottom of each support tower <NUM>.

According to an embodiment, the jacking system <NUM> may include a jacking frame <NUM> and a jacking mechanism <NUM> which are positioned at the bottom of stacked segments <NUM>. The jacking mechanism <NUM> described herein may generally be any suitable hydraulically, pneumatically, or other mechanically actuated system for raising the vertical support structure <NUM>. Accordingly, when additional segments <NUM> need to be added, a dedicated jacking mechanism <NUM> simultaneously raises each of the support towers <NUM> such that additional segments <NUM> may be inserted. Specifically, the jacking frame <NUM> may support the weight of the vertical support structure <NUM> as additional segments <NUM> are positioned below the lowermost stacked segments <NUM>. Additional segments <NUM> are joined to stacked segments <NUM> using any suitable mechanical fasteners, welding, etc. This process may be repeated as needed to raise the total height of the vertical support structure <NUM>.

In certain situations, it may be desirable to protect the tower structure <NUM> and components of the additive printing device <NUM> from the external environment in which they are being used. In such embodiments, the tower cover <NUM> may generally be any suitable material positioned around the vertical support structure <NUM>. For example, the tower cover <NUM> may be a fabric-like material draped over or attached to the vertical support structure <NUM> (e.g., over the support towers <NUM> and/or the gantry beams <NUM>).

As mentioned briefly above, the vertical support structure <NUM> is generally configured for supporting one or more of the printer heads <NUM> and or other modules which facilitate the formation of the tower structure <NUM>. Referring specifically to <FIG>, the additive printing device <NUM> may further include one or more support members, such as support rings <NUM>, that are suspended from the vertical support structure <NUM>, or more specifically from gantry beams <NUM>, above the tower structure <NUM>. For example, as illustrated, the support ring <NUM> is mounted to the gantry beam <NUM> using a vertical positioning mechanism <NUM>. In general, the vertical positioning mechanism <NUM> is configured for adjusting a height or vertical distance <NUM> measured between the gantry beam <NUM> and a top of support ring <NUM> along the vertical direction V. For example, the vertical positioning mechanism <NUM> may include one or more hydraulic actuators <NUM> extending between gantry beam <NUM> and support ring <NUM> for moving support ring <NUM> and printer heads <NUM> along the vertical direction V as tower structure <NUM> is built up layer-by-layer.

As illustrated, the hydraulic actuators <NUM> are configured for adjusting the vertical distance <NUM> to precisely position nozzles <NUM> of the printer heads <NUM> immediately above top <NUM> of the tower structure <NUM>. In this manner, the additive printing process may be precisely controlled. However, it should be appreciated that according to alternative embodiments, the vertical motion of the printer heads <NUM> may be adjusted in any other suitable manner. For example, according to an embodiment, the support ring <NUM> may be rigidly fixed to the gantry beam <NUM> while the support ring <NUM> and/or the printer heads <NUM> are used to facilitate vertical motion to precisely position nozzles <NUM>. For example, the printer heads <NUM> may be slidably mounted to the support ring <NUM> using a vertical rail and positioning mechanism to adjust the vertical position relative to the support ring <NUM> and the tower structure <NUM>.

According to the illustrated embodiment, the printer head(s) <NUM> is movably coupled to the support ring <NUM> such that the nozzles <NUM> may deposit cementitious material <NUM> around a perimeter of tower structure <NUM> while the support ring <NUM> remains rotationally fixed relative to gantry beam <NUM>. In this regard, for example, a drive mechanism <NUM> may operably couple the printer head(s) <NUM> to the support ring <NUM> such that printer head(s) <NUM> may be configured for moving around a perimeter <NUM> of the support ring <NUM> (e.g., about a circumferential direction C) while selectively depositing the cementitious material <NUM>. One exemplary drive mechanism <NUM> is described below and illustrated in the figures, but it should be appreciated that other drive mechanisms are contemplated and within the scope of the present disclosure.

As best shown in <FIG>, for example, the drive mechanism <NUM> may include a ring gear <NUM> that is positioned on the support ring <NUM> and a drive gear <NUM> that is rotatably mounted to printer head <NUM>. Specifically, as illustrated, the ring gear <NUM> is defined on a bottom <NUM> of the support ring <NUM>. Thus, when printer head(s) <NUM><NUM> is mounted on the bottom <NUM> of support ring <NUM>, drive gear <NUM> engages ring gear <NUM>. The drive mechanism <NUM> may further include a drive motor <NUM> that is mechanically coupled to the drive gear <NUM> for selectively rotating the drive gear <NUM> to move printer head(s) <NUM> around a perimeter <NUM> of the support ring <NUM>. In this manner, the support ring <NUM> may remain stationary while printer head(s) <NUM> moves around the support ring <NUM> while depositing the cementitious material <NUM> to form a cross-sectional layer of tower structure <NUM>.

Although the drive mechanism <NUM> is illustrated herein as a rack and pinion geared arrangement using drive gear <NUM> and ring gear <NUM>, it should be appreciated that any other suitable drive mechanism <NUM> may be used according to alternative embodiments. For example, the drive mechanism <NUM> may include a magnetic drive system, a belt drive system, a frictional roller drive system, or any other mechanical coupling between printer head(s) <NUM> and support ring <NUM> which permits and facilitates selective motion between the two.

In addition, in an embodiment, the support ring <NUM> may generally have a diameter that is substantially equivalent to a diameter of the tower structure <NUM>. However, it may be desirable to print the tower structure <NUM> having a non-fixed diameter or a tapered profile. In addition, as illustrated for example in <FIG>, the tower structure <NUM> may include an outer tower wall <NUM> spaced apart along a radial direction R from an inner tower wall <NUM>. For example, the outer tower wall <NUM> may be printed to define a mold for receiving poured concrete, e.g., to decrease printing time and total construction time.

Thus, as shown, the additive printing device <NUM> may include a plurality of concentric support rings <NUM> and printer heads <NUM> for simultaneously printing each of the outer tower wall <NUM> and the inner tower wall <NUM>. Specifically, as illustrated, an outer support ring <NUM> may be positioned above the outer tower wall <NUM> and have a substantially equivalent diameter to the outer tower wall <NUM>. Similarly, the inner support ring <NUM> may be positioned above the inner tower wall <NUM> and have a substantially equivalent diameter to the inner tower wall <NUM>. It should be appreciated that as used herein, terms of approximation, such as "approximately," "substantially," or "about," refer to being within a ten percent margin of error. According to this embodiment, each of outer support ring <NUM> and inner support ring <NUM> may include dedicated printer heads <NUM> and/or other modules for facilitating the printing process of outer tower wall <NUM> and inner tower wall <NUM>, respectively.

Referring again to <FIG>, the printer head(s) <NUM> may include mechanisms for adjusting the position of nozzles <NUM> on printer head(s) <NUM>. For example, printer head(s) <NUM> may include a radial adjustment mechanism <NUM> that is configured for moving print nozzle <NUM> along the radial direction R. Specifically, according to the illustrated embodiment, radial adjustment mechanism <NUM> includes a slide rail <NUM> mounted to a bottom <NUM> of printer head <NUM>. The slide rail <NUM> extends substantially along the radial direction and is configured for slidably receiving the nozzle <NUM>.

The radial adjustment mechanism <NUM> may further include an actuating mechanism <NUM> that moves print nozzle <NUM> along the radial direction R within the slide rail <NUM>. For example, the actuating mechanism <NUM> may include any suitable actuator or positioning mechanism for moving nozzle <NUM> within the slide rail <NUM>. In this regard, for example, the actuating mechanism <NUM> may include one or more of a plurality of linear actuators, servomotors, track conveyor systems, rack and pinion mechanisms, ball screw linear slides, etc..

Referring still to <FIG> and <FIG>, the additive printing device <NUM> may include any other suitable number of subsystems or modules to facilitate and improved printing process or improved finishing of tower structure <NUM>. For example, as best illustrated in <FIG>, the additive printing device <NUM> may include a reinforcement module <NUM> which is movably coupled to the support ring <NUM> and is configured for embedding one or more support members <NUM> at least partially within tower structure <NUM>. In this regard, for example, the reinforcement module <NUM> may be similar to the printer head(s) <NUM> in that engages the support ring <NUM> and may move around a perimeter <NUM> of the support ring <NUM> while depositing the support members <NUM>.

For example, according to an embodiment, the support members <NUM> may be reinforcement bars (i.e., rebar), tensioning cables, or any other suitable structural support members, as explained briefly below. For example, as shown in <FIG>, the reinforcement module <NUM> may embed one or more reinforcement members <NUM> at least partially within one or more of portions of the tower structure <NUM>. In this regard, the reinforcement module <NUM> positions reinforcement members <NUM> at least partially within the tower structure <NUM>. It should be understood that such reinforcement members <NUM> may extend along the entire height of the tower structure <NUM> (e.g., as shown in <FIG>) or along only a portion of the tower height.

Similarly, referring still to <FIG> and <FIG>, the additive printing device <NUM> also may be configured to supply backfill material, for example, via a mechanism movably coupled to the support ring <NUM> and configured for depositing backfill material and/or any other material as described herein. In this regard, for example, such a mechanism may be similar to the printer head(s) <NUM> and/or reinforcement module <NUM> in that it engages the support ring <NUM> and may move around a perimeter <NUM> of the support ring <NUM> while depositing a backfill material <NUM> (see e.g., <FIG>, <NUM>-<NUM>). For example, according to an embodiment, the backfill material <NUM> described herein may include any suitable workable paste that is configured to bind together after curing to form a structure. Suitable materials include, for example, concrete, pitch resin, asphalt, clay, cement, mortar, cementitious compositions, geopolymer materials, polymer materials, or similar materials or compositions.

According to an embodiment, as the tower structure <NUM> is being built up, the additive printing device <NUM> can alternate between depositing reinforcement members <NUM> using the reinforcement module <NUM>, printing the cementitious material <NUM> using printer heads <NUM> and nozzles <NUM>, and backfilling a void using the backfill module. Alternatively, as illustrated in <FIG> and <FIG>, the reinforcement module <NUM> may be positioned adjacent the printer heads <NUM> and configured for unwinding or unrolling the reinforcement members <NUM> or rebar into the print area prior to depositing cementitious material <NUM> such that the reinforcement members <NUM> becomes embedded within or printed over with cementitious material <NUM>. Alternatively, the additive printing device <NUM> may include any other suitable features for compressing or embedding tensioning cable into cementitious material <NUM> before it has solidified or cured. In alternative embodiments, the additive printing device <NUM> is configured to eject the cementitious material <NUM> with short polymer and/or metallic fibers or rings as reinforcements to improve the structural strength of the tower structure <NUM>.

Furthermore, the reinforcement members <NUM> may generally be configured for ensuring that the stresses in the cementitious material <NUM>, e.g., concrete, may remain largely compressive. Thus, the reinforcement members <NUM> may be pretensioned in the cementitious material <NUM> and may be printed around the reinforcement members <NUM> or the printing process may define holes or voids throughout the tower structure <NUM> through which the reinforcement members <NUM> may be placed after curing or for backfilling, and thereafter post-tensioned. In addition, the reinforcement members <NUM> may be cables, tendons (e.g., external vertical pretensioned tendons), and/or subsequently grouted into place. In alternative embodiments, the additive printing device <NUM> may be configured to provide tension to the reinforcement members <NUM> during printing of the tower structure <NUM>. In such embodiments, additive printing device <NUM> may vary a tension of the reinforcement members <NUM> as a function of a cross-section of the tower structure <NUM> during the printing process. Thus, such reinforcement members <NUM> are configured to manage tensile stresses of the tower structure <NUM>.

In another embodiment, the tower structure <NUM> may include, for example, a plurality of reinforcing bars that form a metal mesh (not shown) arranged in a cylindrical configuration to correspond to the shape of the tower structure <NUM>. Further, the cylindrical metal mesh can be embedded into the cementitious material <NUM> of the tower structure <NUM> before the material <NUM> cures and periodically along the height of the tower <NUM>. In addition, the additive printing device <NUM> is configured to print the cementitious material <NUM> in a manner that accounts for the cure rate thereof such that the tower wall <NUM>, as it is being formed, can bond to itself. In addition, the additive printing device <NUM> is configured to print the tower structure <NUM> in a manner such that it can withstand the weight of the wall <NUM> as the additively-formed cementitious material <NUM> can be weak during printing.

In addition, although the description herein refers to the tower structure <NUM> being printed from a single material, e.g., concrete, it should be appreciated that the tower structure <NUM> may be printed using any suitable material, even if different from other sections. In addition, the tower structure <NUM> may have any suitable cross sectional profile. In this regard, as illustrated, the tower structure <NUM> may be substantially cylindrical or have a circular cross section. However, according to still other embodiments, the tower structure <NUM> may be polygonal, elliptical, oval, square, teardrop, airfoil, or any other suitable shape. In addition, according to still another embodiment, the tower structure <NUM> may be tapered or vary in cross-sectional area depending on the vertical position along the tower structure <NUM>.

Referring now to <FIG>, a block diagram of an embodiment of a controller <NUM> of the additive printing device <NUM> is illustrated. As shown, the controller <NUM> may include one or more processor(s) <NUM> and associated memory device(s) <NUM> configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and the like and storing relevant data as disclosed herein). Additionally, the controller <NUM> may also include a communications module <NUM> to facilitate communications between the controller <NUM> and the various components of the additive printing device <NUM>. Further, the communications module <NUM> may include a sensor interface <NUM> (e.g., one or more analog-to-digital converters) to permit signals transmitted from one or more sensors or feedback devices to be converted into signals that can be understood and processed by the processor(s) <NUM>. It should be appreciated that these sensors and feedback devices may be communicatively coupled to the communications module <NUM> using any suitable means, e.g., via a wired or wireless connection using any suitable wireless communications protocol known in the art.

As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. The processor <NUM> is also configured to compute advanced control algorithms and communicate to a variety of Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) <NUM> may generally include memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magnetooptical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) <NUM> may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) <NUM>, configure the controller <NUM> to perform the various functions as described herein.

Referring now to <FIG>, a perspective view of an embodiment of an additively-manufactured structure <NUM> having an access opening <NUM> with a pre-fabricated component(s) <NUM> formed therein is illustrated. The pre-fabricated component(s) <NUM> described herein may include any suitable pre-fabricated component formed in a number of ways. For example, in particular embodiments, as described in detail herein, the pre-fabricated component <NUM> may be a pre-fabricated door assembly <NUM> of the tower structure <NUM>. In particular, as shown, the pre-fabricated door assembly <NUM> has a door frame <NUM> defining an access opening <NUM> and a door for moving between an open position that exposes the access opening <NUM> and a closed position that covers the access opening <NUM>. In such embodiments, as shown in the inset of <FIG>, the reinforcement members <NUM> are arranged within the composite material <NUM> around the access opening <NUM>. More particular, in certain embodiments, as shown, the reinforcement members <NUM> may be arranged within the composite material <NUM> at a plurality of different angles with respect to the access opening <NUM>.

In certain embodiments, the pre-fabricated door assembly <NUM> is derived/produced by position or printing a cast component (not shown) to define the access opening <NUM> and then depositing cementitious material within the cast component to complete production of the pre-fabricated door assembly <NUM>. In such embodiments, the cast component is an integral part of the pre-fabricated door assembly <NUM> and is left permanently embedded in the tower structure <NUM> as the tower structure <NUM> is built up. In particular, in certain embodiments, the cast component for the pre-fabricated door assembly <NUM> may be formed of a different material composition than the composition of the material introduced into the cast component for completing the pre-fabricated door assembly <NUM> or used for printing the remainder of the tower structure <NUM>.

Referring now to <FIG>, as mentioned, the pre-fabricated component <NUM> may also be a pre-fabricated foundation assembly <NUM>. Further, as shown, the pre-fabricated foundation assembly <NUM> may include a plurality of foundation segments <NUM>. Thus, in certain embodiments, the method of the present disclosure may include arranging the plurality of foundation segments <NUM> together to form a foundation of the tower structure <NUM>. In such embodiments, as shown, a gap <NUM> exists between each of the plurality of foundation segments <NUM> with the portions <NUM> of the reinforcement members <NUM> protruding from the foundation segments <NUM> within the gaps <NUM>. Moreover, in certain embodiments, the pre-fabricated component <NUM> also is derived/produced by position or printing a cast component (not shown). In particular, in certain embodiments, the cast component for the pre-fabricated foundation assembly <NUM> may include a different material composition than the composition of the material introduced into the cast component for completing the pre-fabricated foundation assembly <NUM> or used for printing the remainder of the tower structure <NUM>.

As such, such pre-fabricated components <NUM> can be constructed prior to printing the tower structure <NUM> such that the components <NUM> can be easily incorporated therein, or the pre-fabricated components <NUM> can be constructed in situ during printing of the tower structure <NUM>. For example, in an embodiment, the pre-fabricated components <NUM> may be formed via casting both on or off site. In alternative embodiments, the pre-fabricated components <NUM> may be formed via the additive printing device <NUM>, i.e., by printing and depositing the cementitious material <NUM> via the printer head(s) <NUM> to form the pre-fabricated component <NUM> prior to positioning the component <NUM> adjacent to the support surface <NUM> of the tower structure <NUM> for printing remaining portions of the structure <NUM>.

Referring now to <FIG>, illustrated is an embodiment of an additively-manufactured structure <NUM> having a reinforced access opening <NUM> with a backfilled void <NUM> and a pre-fabricated door assembly <NUM> according to the present disclosure. The backfilled void <NUM> described herein may include any suitable backfilled void <NUM> formed in a number of ways. For example, in a particular embodiment, as shown in <FIG> and <FIG>, the backfilled void <NUM> may be formed all at once by forming/building up the tower structure <NUM> to define a void <NUM> and leaving the void <NUM> to be backfilled with the help of one-piece formwork <NUM>, for example, and then backfilling the void <NUM> all at once after the one or more reinforcement members <NUM> are placed into/through the void <NUM>.

In another embodiment, as shown in <FIG> and <FIG>, the backfilled void <NUM> may be formed incrementally with continuous or near continuous forming of the tower structure <NUM>, continuous or near continuous expansion of the void <NUM> from the backfilled void <NUM> portion, and continuous or near continuous backfilling of the expanded void <NUM> via stackable formwork <NUM>, for example. As such, in certain embodiments, the backfilled void <NUM> is not formed all at once but instead is formed continuously or near continuously during continuous or near continuous printing of the tower structure <NUM>, which helps to prevent or significantly reduce cold joint formation between the older backfilled void <NUM>, the newer backfilled void <NUM>, and the surrounding tower structure <NUM>. In a different embodiment, and as mentioned herein in detail, the backfilled void <NUM> may be formed by position or printing a printed formwork (not shown) to define the void <NUM> and then depositing cementitious material to complete production of the printed formwork such that it can be used for completing production of the backfilled void <NUM>. As such, in certain embodiments, the formwork <NUM> remains an integral part of the tower structure <NUM> even after the void <NUM> is backfilled and, therefore, the formwork <NUM> is left permanently embedded in the tower structure <NUM> as the tower structure <NUM> is built up.

Moreover, and still referring to <FIG>, the portions of the reinforcement members <NUM> protruding from the pre-fabricated door assembly <NUM>, and the portions of the reinforcement members <NUM> extending across the backfilled void <NUM> are configured to reinforce the cementitious material around the access opening <NUM>. In certain embodiments, as shown in <FIG>, the reinforcement members <NUM> are incorporated into the backfilled void <NUM> and the backfilled void is incorporated into the surrounding tower structure <NUM> above the access opening <NUM> to reinforce the access opening <NUM>. In particular, as shown in <FIG>, the reinforcement members <NUM> may be arranged within the backfilled void <NUM> at a plurality of different angles with respect to the access opening <NUM>. For example, in one embodiment, the reinforcement members <NUM> are arranged within the backfilled void <NUM> in a grid. In another embodiment, the reinforcement members <NUM> are extended horizontally across the void <NUM>, and the reinforcement members <NUM> are extended vertically across the void <NUM>. In another embodiment, the reinforcement members <NUM> may be arranged to take a plurality of different angles with respect to the access opening <NUM> when placed into the backfilled void <NUM>. The reinforcement member <NUM> may take the form of a U-shaped reinforcement member (see e.g., <FIG>) but may also be L-shaped, T-shaped, E-shaped, etc..

Referring now to <FIG>, a flow diagram of one embodiment of a method <NUM> for additively-manufacturing a structure with a reinforced access opening is provided. In particular, the method <NUM> can be used to form the tower structure <NUM> of <FIG> using the additive printing device <NUM> of <FIG>, or to form any other suitable structure, tower, or tall structure using any other suitable additive printing device. In this regard, for example, the controller <NUM> of <FIG> may be configured for implementing the method <NUM>. However, it should be appreciated that the method <NUM> is discussed herein only to describe aspects of the present disclosure and is not intended to be limiting.

Further, though <FIG> depicts a control method having steps performed in a particular order for purposes of illustration and discussion, those of ordinary skill in the art, using the disclosures provided herein, will understand that the steps of any of the methods discussed herein can be adapted, rearranged, expanded, omitted, or modified in various ways without deviating from the scope of the present disclosure. Moreover, although aspects of the methods are explained with respect to the tower structure <NUM> and the additive printing device <NUM> as an example, it should be appreciated that these methods may be applied to the operation of additive printing device to form any suitable tower structure.

Furthermore, as described herein, it may be advantageous to incorporate one or more backfilled void(s) <NUM> into the tower structure <NUM> to yield a reinforced access opening <NUM> or any opening or aperture through or partially through the tower wall <NUM>. Accordingly, the method <NUM> described herein provides a method for manufacturing a tower structure <NUM> that incorporates such backfilled void(s) <NUM>. In particular, as shown at (<NUM>), the method <NUM> includes printing, via an additive printing device <NUM> having at least one printer head <NUM>, a portion of the tower structure <NUM> adjacent to a support surface <NUM> of a cementitious material. In such embodiments, the printed portion of the tower structure <NUM> defines an access opening <NUM>. For example, the additive printing device <NUM> of <FIG> and one-piece formwork (see e.g., <FIG>) or stackable formwork (see e.g., <FIG> and <FIG>), for example, can be used to complete the method <NUM> described herein. Thus, as previously explained, the method <NUM> may include positioning the vertical support structure <NUM> above the support surface <NUM> of the tower structure <NUM>, suspending a support member from the vertical support structure <NUM> (such as support ring <NUM>), and movably coupling the printer head(s) <NUM> to the support member.

Referring back to <FIG>, and as shown at (<NUM>), the method <NUM> also includes providing a void <NUM> of the cementitious material at a top boundary of the access opening <NUM>. The void <NUM> may be formed all at once by forming/building up the tower structure <NUM> to define the entire intended void <NUM> and leaving the void <NUM> to be backfilled with the help of one-piece formwork <NUM>, for example. The void <NUM> also may be formed incrementally by continuous or near continuous expansion of the void <NUM>, and continuous or near continuous printing of the tower structure <NUM> around the void <NUM> and defining the expanding void <NUM>, for example, such that the void <NUM> has older and newer defined space. The void <NUM> also may be formed by position or printing a printed formwork (not shown) to define the void <NUM>, such that the formwork <NUM> remains an integral part of the tower structure <NUM> and is left permanently embedded in the tower structure <NUM> as the tower structure <NUM> around the void <NUM> and defining the void <NUM> is built up. In certain embodiments, the void <NUM> may be provided before positioning any pre-fabricated component(s) <NUM>, significant formwork <NUM>, or cast component(s) (not shown) (see e.g., <FIG>). In other embodiments, the void <NUM> may be provided before positioning any significant formwork <NUM> or cast component(s) (not shown), but after positioning of any pre-fabricated component(s) <NUM> (see e.g., <FIG>). In some embodiments, the entire intended void <NUM> may be provided only after positioning of the pre-fabricated component(s) <NUM>, any significant formwork <NUM>, or cast component(s) (not shown) (see e.g., <FIG>).

Referring back to <FIG>, as shown at (<NUM>), the method <NUM> also includes placing one or more reinforcement members <NUM> in the void <NUM> such that the one or more reinforcement members <NUM> extend across the void <NUM>. In particular, the one or more reinforcement members <NUM> may be arranged within the void <NUM>, i.e., prior to the void <NUM> being backfilled or during continuous or near continuous backfilling of the void <NUM>-at a plurality of different angles. For example, in one embodiment, the reinforcement member(s) <NUM> are arranged within the void <NUM> in a grid. In another embodiment, the reinforcement member(s) <NUM> are extended horizontally across the void <NUM>, and the reinforcement members(s) <NUM> are extended vertically across the void <NUM>. In another embodiment, the reinforcement member(s) <NUM> may be arranged to take a plurality of different angles with respect to the access opening <NUM> when placed into the backfilled void <NUM>. Depending on the embodiment, the form, shape, and structure of the reinforcement member(s) <NUM> (e.g., U-shaped, L-shaped, T-shaped, E-shaped), and depending on the presence of pre-fabricated component(s) <NUM>, any significant formwork <NUM>, or cast component(s) prior to (<NUM>), the method <NUM> at (<NUM>) may include placing the reinforcement member(s) <NUM> in the void <NUM> and extending the one or more reinforcement members in the void in whatever direction is not obstructed by either the pre-fabricated component(s) <NUM>, the formwork <NUM>, or the cast component(s) (see e.g., <FIG>).

As shown at (<NUM>), the method <NUM> also includes continuing to print the printed portion of the tower structure <NUM> around the void <NUM> to build up the tower structure <NUM>. The additive printing device <NUM> of <FIG> and the one-piece formwork (see e.g., <FIG>) or the stackable formwork (see e.g., <FIG> and <FIG>), for example, may be used.

As shown at (<NUM>), the method <NUM> also includes backfilling the void <NUM> with the backfill material <NUM> to incorporate the reinforcement member(s) within the void <NUM> into the printed portion of the tower structure <NUM>. In particular, in an embodiment, (<NUM>) may include depositing or backfilling, via the additive printing device <NUM>, for example, a backfill material <NUM> into the currently available void <NUM> of the tower structure <NUM>. Again, and for example, the additive printing device <NUM> of <FIG> and one-piece formwork (see e.g., <FIG>) or stackable formwork (see e.g., <FIG> and <FIG>), for example, can be used. "Currently available void" as used herein refers to continuous or near continuous manufacturing situations to distinguish between the older backfilled void <NUM>, which is void <NUM> that has been backfilled earlier in time and prior to the continued expansion of the void <NUM>-and the newer backfilled void <NUM>-which is void <NUM> that has been backfilled later in time after the continued expansion of the void <NUM>. Therefore, and returning to (<NUM>) of method <NUM>, the backfilled void <NUM> may be formed by backfilling the currently available void <NUM> all at once after the reinforcement member(s) <NUM> are placed into/through the currently available void <NUM>.

In another embodiment, the backfilled void <NUM> may be formed incrementally with (<NUM>) continuous or near continuous forming of the tower structure <NUM>, (<NUM>) continuous or near continuous expansion of the void <NUM> (from what may have be currently available for backfilling earlier in time, or from what may have been backfilled earlier in time), and (<NUM>) continuous or near continuous backfilling of the expanded void <NUM> beyond what was the previous currently available void <NUM>, which helps to prevent or significantly reduce cold joint formation between the older backfilled void <NUM>, the newer backfilled void <NUM>, and the surrounding tower structure <NUM>.

Referring now to <FIG>, a schematic diagram of an embodiment of a sequence <NUM> by which the tower structure of <FIG> is manufactured is illustrated. As shown at (<NUM>) of the sequence <NUM>, a portion of the tower structure <NUM> is printed of a cementitious material <NUM> to define the access opening <NUM>. Next, as shown at (<NUM>) of sequence <NUM>, a formwork 204a is positioned and installed along the printed portion of the tower structure <NUM> defining the access opening <NUM>.

As shown at (<NUM>) of sequence <NUM>, a void <NUM> of the cementitious material <NUM> is provided at a top boundary of the access opening <NUM> by continuing to print the tower structure <NUM> up above the top boundary of the access opening <NUM> and the formwork 204a. Also, as shown at (<NUM>) of sequence <NUM>, one or more reinforcement members 30a-the same horizontal full ring rebar reinforcement members 30a incorporated and part of the printed portions of the tower structure <NUM>-are extended across the void <NUM> and, therefore, remain placed in the void <NUM> such that the one or more reinforcement members 30a extend horizontally across the void <NUM>. Also, as shown at (<NUM>) of sequence <NUM>, the formwork 204a facilitates the continued printing of the tower structure <NUM> above the top boundary of the access opening <NUM> (by helping to support the one or more horizontal reinforcement members 30a) and facilitates the continued printing of the tower structure <NUM> above the top boundary of the access opening <NUM>.

Optionally, between (<NUM>) and (<NUM>) of sequence <NUM>, the sequence <NUM> may include placing a liner along formwork 204a at the top boundary of the access opening <NUM> on the inside surface of the void <NUM> to facilitate removal of the formwork 204a after formation of the backfilled void <NUM> at (<NUM>) of sequence <NUM>.

Still referring to <FIG>, as shown at (<NUM>) of sequence <NUM>, one or more reinforcement members 30b are extended across the void <NUM> and, therefore, remain placed in the void <NUM> such that the one or more reinforcement members 30b extend vertically across the void <NUM>. Also, as shown at (<NUM>) of sequence <NUM>, the formwork 204a defines and obstructs the bottom of the void <NUM> and, therefore, the one or more vertical reinforcement members 30b are placed into the void <NUM> through the top or through the sides of the void <NUM>, in between the one or more horizontal reinforcement members 30a, to form a grid of reinforcement members <NUM>. Also, as shown at (<NUM>) of sequence <NUM>, the formwork 204a facilitates formation of the backfilled void <NUM> of the tower structure <NUM> by helping to support the one or more vertical reinforcement members 30b, the additional formwork 204b, and the backfill material <NUM> at (<NUM>) of sequence <NUM>.

As shown at (<NUM>) of sequence <NUM>, a cold joint primer may also be applied to the void <NUM>. In addition, as shown at (<NUM>) of sequence <NUM>, a formwork 204b is positioned and installed along the open sides of void <NUM> of the tower structure <NUM>, which leaves the top of the void <NUM> open for backfilling. Next, at (<NUM>) of sequence <NUM>, the void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b within the void <NUM> into the printed portion of the tower structure <NUM> and to form the backfilled void <NUM>.

Referring now to <FIG>,a schematic diagram of an embodiment of a sequence <NUM> by which the tower structure of <FIG> is manufactured is illustrated. In particular, the sequence <NUM> involves the use of stackable formwork <NUM> and continuous or near continuous printing techniques. As shown at (<NUM>) of sequence <NUM>, a portion of the tower structure <NUM> is printed of a cementitious material <NUM> to define the access opening <NUM>. As shown at (<NUM>) of sequence <NUM>, a formwork 204a is positioned and installed along the printed portion of the tower structure <NUM> defining the access opening <NUM>.

As shown at (<NUM>) of sequence <NUM>, a void <NUM> of the cementitious material <NUM> is provided at a top boundary of the access opening <NUM> by continuing to print the tower structure <NUM> above the top boundary of the access opening <NUM> and the formwork 204a, and one or more horizontal reinforcement members 30a are extended across the void <NUM>. As shown at t (<NUM>) of sequence <NUM>, one or more vertical reinforcement members 30b are placed and extended across the void <NUM> to form a grid of reinforcement members <NUM> with the one or more horizontal reinforcement members 30a, and a stackable formwork <NUM> is positioned and installed along the open sides of void <NUM> of the tower structure <NUM>, but also extending above the elevation of the void <NUM> or the printed tower structure <NUM>, which leaves the top of the void <NUM> open for backfilling, and which leaves more room for continued printing of the tower structure <NUM> along and above the elevation of the void <NUM>, and which allows for expansion of the void <NUM>.

As shown at (<NUM>) of sequence <NUM>, a first portion of the void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b within the first backfilled portion of the void <NUM> into the printed portion of the tower structure <NUM> and to form at least a portion of the backfilled void <NUM>. As shown at (<NUM>) of sequence <NUM>, the stackable formwork <NUM> facilitates the continuous or near continuous printing of the tower structure <NUM> above the top boundary of the access opening <NUM> and above the first backfilled portion of the backfilled void <NUM> to help expand the void <NUM>, and also helps mitigate against the effects of cold joint formation. Next, as shown at (<NUM>) of sequence <NUM>, the expanded void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b within the expanded void <NUM> into the printed portion of the tower structure <NUM> and to form a second, newer portion of the backfilled void <NUM>.

Referring now to <FIG>, a schematic diagram of an embodiment of a sequence <NUM> by which the tower structure of <FIG> is manufactured is illustrated. In particular, the sequence <NUM> involves the use of one piece formwork <NUM>. As shown at (<NUM>) of sequence <NUM>, a portion of the tower structure <NUM> is printed of a cementitious material <NUM> to define the access opening <NUM>. As shown at (<NUM>) of sequence <NUM>, a falsework <NUM> is positioned and installed within the access opening <NUM> to provide support for the continued printing of the printed portion of tower structure <NUM> above the top boundary of the access opening <NUM>. Also, at (<NUM>) of sequence <NUM>, the tower structure <NUM> above the top boundary of the access opening <NUM> is continued to be printed to define the void <NUM> such that the one or more horizontal reinforcement members 30a of the printed portion of the tower structure <NUM> above the top boundary of the access opening <NUM> extend across the void <NUM>.

As shown at (<NUM>) of sequence <NUM>, one or more vertical reinforcement members 30b are placed and extended across the void <NUM> to form a grid of reinforcement members <NUM> with the one or more horizontal reinforcement members 30a. As shown at (<NUM>) of sequence <NUM>, the falsework <NUM> is removed. Also, as shown at (<NUM>) of sequence <NUM>, as there is no formwork, falsework, or pre-fabricated components in the tower structure <NUM> to obstruct the bottom of the void <NUM>, the one or more vertical reinforcement members 30b may be placed in the void <NUM> through the bottom of the void <NUM>, in between the one or more horizontal reinforcement members 30a, to form a grid of reinforcement members <NUM>, and fixed in placed via fixtures (see e.g., <FIG>) such that the reinforcement member grid <NUM> is tied in place. Also, at (<NUM>) of sequence <NUM>, the continued printing of tower structure <NUM> above the top boundary of the access opening <NUM> and the continued formation of the void <NUM> are paused.

As shown at (<NUM>) of sequence <NUM>, a formwork 204a is positioned and installed along the printed portion of the tower structure <NUM> defining the access opening <NUM>, and a one piece formwork <NUM> is positioned and installed along the open sides of void <NUM> of the tower structure <NUM>, but also extending above the elevation of the void <NUM> or the printed tower structure <NUM>, which leaves the top of the void <NUM> open for backfilling, and which leaves more room for continued printing of the tower structure <NUM> along and above the elevation of the void <NUM>.

Still referring to <FIG>, as shown at (<NUM>) of sequence <NUM>, the currently available void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b within the backfilled portion of the currently available void <NUM> into the printed portion of the tower structure <NUM> and to form at least a portion of the backfilled void <NUM>.

As shown at (<NUM>) of sequence <NUM>, a cold joint primer is applied to the portion of the backfilled void <NUM> formed at (<NUM>). Also, as shown at (<NUM>) of sequence <NUM>, the one piece formwork <NUM> facilitates the continued printing of the tower structure <NUM> above the top boundary of the access opening <NUM> and above the portion of the backfilled void <NUM> formed at (<NUM>) that expanded the void <NUM>. As shown at (<NUM>) of sequence <NUM>, the expanded void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b into the printed portion of the tower structure <NUM>, and to finish forming the backfilled void <NUM>.

Referring now to <FIG>, a schematic diagram of an embodiment of a sequence <NUM> by which the tower structure of <FIG> is manufactured is illustrated. In particular, the sequence <NUM> involves the use of stackable formwork <NUM> and continuous or near continuous printing techniques. As shown at (<NUM>) of sequence <NUM>, a portion of the tower structure <NUM> is printed of a cementitious material <NUM> to define the access opening <NUM>. As shown at (<NUM>) of sequence <NUM>, a falsework <NUM> is positioned and installed within the access opening <NUM> to provide support for the continued printing of tower structure <NUM> above the top boundary of the access opening <NUM>. Also, as shown at (<NUM>) of sequence <NUM>, the tower structure <NUM> above the top boundary of the access opening <NUM> is continued to be printed to define the void <NUM> such that the one or more horizontal reinforcement members 30a of the printed portion of the tower structure <NUM> above the top boundary of the access opening <NUM> extend across the void <NUM>.

As shown at (<NUM>) of sequence <NUM>, one or more vertical reinforcement members 30b are placed and extended across the void <NUM> to form a grid of reinforcement members <NUM> with the one or more horizontal reinforcement members 30a. Also, at (<NUM>) of sequence <NUM>, the falsework <NUM> is removed. Also, as shown at (<NUM>) of sequence <NUM>, as there is no formwork, falsework, or pre-fabricated components in the tower structure <NUM> to obstruct the bottom of the void <NUM>, the one or more vertical reinforcement members 30b may be placed in the void <NUM> through the bottom of the void <NUM>, in between the one or more horizontal reinforcement members 30a to form the grid of reinforcement members <NUM>. Also, as shown at (<NUM>) of sequence <NUM>, the continued printing of tower structure <NUM> above the top boundary of the access opening <NUM> and the continued formation of the void <NUM> are paused.

As shown at (<NUM>) of sequence <NUM>, a formwork 204a is positioned and installed along the printed portion of the tower structure <NUM> defining the access opening <NUM>, and a first piece of stackable formwork 205a is positioned and installed along at least a portion of the open sides of void <NUM> of the tower structure <NUM>, which leaves the top of the void <NUM> open for backfilling, and which leaves more room for continued backfilling of the void <NUM> above the elevation of the first piece of stackable formwork 205a and for continued formation of the backfilled void <NUM>.

As shown at (<NUM>) of sequence <NUM>, a first portion of void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b within the first backfilled portion of the void <NUM> into the printed portion of the tower structure <NUM> and to form at least a portion of the backfilled void <NUM>. In addition, there may be a loop as needed between (<NUM>) and (<NUM>), wherein a second piece of stackable formwork 205b (and so on and so forth) is positioned and stacked above the first piece of stackable formwork 205b, along the void <NUM> of the tower structure <NUM>, which leaves the top of the void <NUM> open for backfilling, and which leaves more room for continued backfilling of the void <NUM> above the elevation of the first piece of stackable formwork 205a and for continued formation of the backfilled void <NUM>, and then a second portion of void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b into the printed portion of the tower structure <NUM>.

As shown at (<NUM>) of sequence <NUM>, a depending on the number of loops between (<NUM>) and (<NUM>) needed, the stackable formwork <NUM> facilitates the continuous or near continuous printing of the tower structure <NUM> above the top boundary of the access opening <NUM> and above the first and second backfilled portion of the backfilled void <NUM> to help expand the void <NUM>, and also to help mitigate against the effects of cold joint formation. Also, as shown at (<NUM>) of sequence <NUM>, a cold joint primer may be applied to the portion(s) of the backfilled void <NUM> formed during the loop between (<NUM>) and (<NUM>). As shown at (<NUM>) of sequence <NUM>, the expanded void <NUM> is backfilled with the backfill material <NUM> to incorporate the one or more reinforcement members 30a,b into the printed portion of the tower structure <NUM>, and to finish forming the backfilled void <NUM>.

Claim 1:
A method of additively-manufacturing a structure (<NUM>) having a reinforced access opening (<NUM>), the method comprising:
printing, via an additive printing device (<NUM>) having at least one printer head (<NUM>), a portion of the structure adjacent to a support surface (<NUM>) of a cementitious material (<NUM>), the printed portion of the structure (<NUM>) defining an access opening (<NUM>);
providing a void (<NUM>) of the cementitious material (<NUM>) at a top boundary of the access opening (<NUM>);
placing one or more reinforcement members (<NUM>) in the void (<NUM>) such that the one or more reinforcement members (<NUM>) extend across the void (<NUM>);
continue printing the printed portion of the structure (<NUM>) around the void (<NUM>) to build up the structure (<NUM>); and
backfilling the void (<NUM>) with a backfill material (<NUM>) to incorporate the one or more reinforcement members (<NUM>) within the void (<NUM>) into the printed portion of the structure (<NUM>).