US20220412072A1

US20220412072A1 - Connection system for volumetric modular construction

Info

Publication number: US20220412072A1
Application number: US17/742,427
Authority: US
Inventors: Matthew Clark
Original assignee: Arup Ip Management Ltd
Current assignee: Arup Ip Management Ltd
Priority date: 2021-05-12
Filing date: 2022-05-12
Publication date: 2022-12-29

Abstract

A modular unit connection system for jointing together pre-fabricated rectangular modular building units to form a multistory building. The building units can be completely fitted out and this connection system allows for positive structural connection using liquid grout filled columns, without bolting or welding and without the requirement for access to the connections from inside the pre-finished building module interiors. The four corner columns of the box-shaped modules are steel square hollow sections. This connection system uses a unique connector tube passing from the bottom of the column above, through a horizontal connector plate containing a guidance system and into the top of the hollow column below, and then a system of grouting the inside of the column, from an access position on top the upper most module to form the final positive structural connection.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. Non-Provisional Patent Application that claims priority to U.S. Provisional Patent Application Ser. 63/187,487 filed on May 12, 2021, the entire contents of which are hereby incorporated by reference in their entirety.

FIELD OF THE EMBODIMENTS

The invention relates to modular buildings, in particular to a system for connecting modular units together vertically and horizontally to construct multi-unit modular building structures.

BACKGROUND OF THE EMBODIMENTS

It is increasingly clear that as constraints around cost, health and safety, sustainability and speed of construction continue to get more and more stringent, traditional methods of construction need to be reconsidered. The idea of shifting majority of the construction activities to an off-site location is very favorable to meet the above-mentioned criteria. Pre-fabricating parts of a building and then transporting them to the construction site has been done for a long time but in recent times, fully factory-built modules connected to each other on site is gaining popularity due to the advantages it provides. Innovatively connecting the modules together with limited access to the location of the connection is where the challenge lies. This application intends to obtain a provisional patent for one such connection system.
The problem we are attempting to solve with this embodiment is the means of making structural connection between each prefabricated volumetric module. In a conventionally built building, the structural elements (beams, columns, braces etc.) are all accessible from all directions and may be bolted or welded together by conventional means. Those connections are designed to meet the building code requirements for robustness and for the forces applied. In modular construction, structural elements for any one module are also fully accessible in the module factory. However, once on site, the structural elements of the building are almost completely hidden by the furnishings of the modules. The structural connection requirements as per the building code remain the same, i.e., all beams and columns must be positively and robustly connected between the different modules, but there is no easy access to be able to apply bolts or welds to the structural elements. Therefore, a non-conventional connection system must be employed if modular construction is to be efficient. The embodiment and means of this connection system directly affect the speed of construction, cost of construction and the strength limitations of the building as a whole. Specific challenges are listed as follows:

1) Means of access to the connections. Ideally modular construction employs factory finished modules that are as complete as possible with no access holes for structural connection. Access panels or ‘leave-out’ areas of finishes are not ideal as they require more construction activities on site. When all interiors are finished and the facades attached to the modules, the only access to the connections at the bottom of the module are from the top of the module, approximately 10 to 12′ above.
2) Tolerance management at connections. Tolerance management means the ability of the connection design to be able to accept small (but important) tolerance deviations of the connected parts and still be able to make a positive connection across the joint meeting all the force transfer and robustness requirements. In practice in modular construction, what this means is that the modules are not built to the perfect size and squareness and when they are stacked together, they do not meet perfectly aligned at the connections. The connection system must be able to accept this out-of-tolerance, connect the mods at the required strength and also provide the means of correcting the geometry back to a best-case position for the following floor. A typical tolerance requirement distance is ¾″ out-of-position in any direction.
3) Module placement guidance at connections. As a module is lowered into position it is hung from a crane and may have one or two guidance lines being held by construction crew. The module must be placed on top of the module below as close to its ideal position as possible to meet the requirements of point 2 above. This distance is typically within 1/16″ at once corner. This is generally not possible using the crane and leader lines alone. There must be a guidance system that brings the mod to its ideal location. This guidance system is best achieved at the connection itself
4) Strength and Robustness at connections. The building codes are no different between conventional construction and modular construction. The structural connections between modules are required to meet all force and robustness requirements. These requirements vary depending on the size, shape, and location of the building, but a useful connection system will be versatile and strong enough to be used in many instances of buildings. Forces can be created by gravity, wind, seismic action, temperature etc. In summary there are two main components.
- a) Vertical forces in columns between modules. The connection between columns must transfer vertical forces and tension forces. Building codes typically require a minimum tension strength, even if structural analysis shows no tension is present.
- b) Horizontal forces between modules. The horizontal joints between modules must not be allowed to open or close. These horizontal forces that exist in floors of conventional buildings are called diaphragm forces. Building codes typically have minimum requirements for diaphragm forces expressed as minimum tension forces in floor beams between columns that must be met. In practice for modular construction, to meet these requirements, the columns of each module must be connected to columns of neighboring modules with a minimum strength
- c) Fire Robustness at connections. Columns and beams in multistory buildings must be fire protected

Currently utilized solutions to these challenges do not address all the issues that this embodiment does. Many require access holes or panels through the fabric of the module finishes, which is not ideal. Many are quite limited in their strength capabilities, meaning the height of building they can be utilized in is limited. Some are complex in their execution, requiring increased time on site to make the connections. Some have limited tolerance adjustability, requiring increased fabrication costs to achieve tighter tolerances in the fabrication shop.
Our embodiments intend to improve holistically on all these solutions by using a different approach. Our solution is an improvement in the following ways:

- Requires less access. Only needs access at top of a module
- Simple tolerance management. No bolts or welds are used, so tolerances are managed by parts sliding across each other and shims.
- Provides integrated module placement guidance as part of the same system
- Is stronger than other connection systems for the same size column
- Has some inherent fire rating, that bare steel systems do not have

Various systems are known in the art. However, their function and means of operation are substantially different from the present embodiments.

SUMMARY OF THE EMBODIMENTS

Modular building units are constructed in a factory. This embodiment applies to the columns within the units, which are usually at the corners of the box shape module and also occasionally along the sides. The building plan is such that when modular units are placed together to form a building, columns are aligned between units stacked vertically, and columns are adjacent to each other where units are side by side. The embodiments allow for units to be fabricated and placed imperfectly, as is required in real-world construction and is one of the benefits of this embodiments.
Engineering principals and building codes require that that the modules are positively connected together with structural components meeting the strength requirements of the building code. This embodiment is the means of making those connections in the vertical direction between columns above and below and also in the horizontal direction between columns side to side. The embodiments enable these connections in one integrated system.
The columns are hollow steel sections. On the underside of the columns a special hollow prong which projects downward. This is an anchorage device that enters the top of the column in the module below. When the modules are stacked, the prong passes through a horizontal connecting plate. The horizontal connector plate extends horizontally to cover the tops of all adjacent columns from adjacent modules. The plate is the means of connecting the modules together in the horizontal direction. The plate become sandwiched between the columns of the modules below and the columns of the modules above. The plate has a hole for each column prong that projects through it from above into the columns below. The horizontal plate also has guidance attachments that can be adjusted with screws to resolve construction tolerances. The guidance system physically guides the prong and thus the whole module into the correct designed position as the next module is lowered on a crane from above.
Once the module above is placed, the whole column including the voids within the column and around and within the hollow guidance prong is filled with a high strength flowable structural grout. A grout tube delivers the grout from a pump placed on the roof of the module, down the column, through the hollow prong. From this position, the grout passes back up the inside of the column in the annulus between the prong or grout tube and outside wall of the column. The operator stops the filling process when they witness the grout appear at the desired level inside the column, viewed form their vantage point on top of the module. Once the grout has cured, the connection has achieved the required structural strength in the vertical and horizontal directions, locking the modules together.
A modular building column connection having a concrete or grout infill inside a composite hollow steel section column; where the composite hollow steel section column comprises an internal steel protrusion from an upper column to a lower column; and which creates a structural load path for tension and shear between building modules.
Another embodiment of the embodiments includes, a modular building column connection comprising: a concrete or grout infill inside a composite hollow steel section column; where the composite hollow steel section column comprises an internal steel protrusion from an upper column to a lower column; a prong; and which creates a structural load path for tension and shear between building modules.
The embodiments also include a method for a modular unit connection system, comprising jointing together pre-fabricated rectangular modular building units; wherein the pre-fabricated rectangular modular building units form a multistory building; and where the building units can be completely fitted out liquid grout filled columns. The method eliminates the need for bolting or welding and the requirement for access to connections from inside pre-finished building module interiors is also eliminated.
The modular building column connection comprises modules that are box shaped and contain 4 corner columns. The 4 corner columns are steel square hollow sections. There is structural framing of the modules side walls, floor, and ceiling. The system comprises a connector tube passing from the bottom of the columns above and through a horizontal connector plate containing a guidance system and into a top region of the hollow column. The method also comprises a system for grouting of the columns from the inside from an access position located on top of an upper most region of the module whereby forming a final positive structural connection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the basic structural frame of a single modular unit.

FIG. 2 is a view of 3 pairs of modules stacked 3 floors high (total 6 modules) showing the adjacency of the module columns.

FIG. 3 is a view of the connection showing the column in the module above, the column in the module below and the diaphragm connector plate. The connector plate is prepared for a 4-column position where 4 separate columns from 4 neighboring modules are located together. The other 3 columns are not shown for clarity.

FIG. 4 is similar view to FIG. 3 , but shown as a cut-away to review the internal components.

FIG. 5 is an exploded view of the connection shown in FIG. 3 and FIG. 4 .

FIG. 6 is a cut away view of the top of a column.

FIG. 7 is a view of the horizontal connector plate.

FIG. 8 is a cut away view of the bottom of a column.

FIG. 9 is a plan diagram of a module showing the different arrangement of guidance fins on the 4 different corners of a rectangular module.

FIG. 10 is a cut away view showing the top of a column including the grout filled up to a temporary position below the next connection to be made.

FIG. 11 is a view of the top of 4 columns with the horizontal connector plate installed on top.

FIG. 12 shows the components used to manage tolerance. The system of screws used to position the horizontal connector plate correctly is shown. The guidance nub on the connector plate is shown along with the guidance fin on the prong that is guided into position by the guidance nub as the column is lowered.

FIG. 13 shows 3 time-lapse views of a column being installed into the column below.

FIG. 14 shows the arrangement at the top of a column during the grouting procedure.

FIG. 15 shows the route that fluid grout takes during the grouting procedure.

FIG. 16 shows a diagram of the final condition with cured grout and the load path through the connection if external forces attempt to pull modules apart vertically.

FIG. 17 shows a diagram of the final condition with cured grout and the load path through the connection if external forces attempt to pull modules apart horizontally.

FIG. 18 is a cut-away view of an alternate embodiment where stiffener plates are added through the section of the column to enable welding on of beams allowing for the creation of a rotationally stiff moment connection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The connection system can be employed in a variety of module designs, so long as those modules have columns along their sides or corners adjacent to a neighboring module's column. The size and shape of the in-fill beams can vary depending on the use of the module and the building's stability system. The connection system can perform as part of gravity only resisting modules, where the building has a separate lateral system, or the connection can perform as part of modules that provide the building's lateral system. The connection of beams to the column and any other in-fill framing is not discussed here since it is not part of the embodiments. For the purposes of this provisional application all diagrams shall only show the module's columns and shall omit all other beams and framing for clarity.
Referring to FIG. 1 , a common feature of all modules is at least 4 columns (2). These columns are hollow structural steel sections. At the top and bottom of each column are the connection points (3). The embodiment of the embodiments lays within the column (1) and the connections (3). Referring to FIG. 2 , these connection points (3) are the only and complete means of connecting the modules together structurally to create a complete building structure. When the modules are arranged together in a building structure, adjacent columns become grouped into column groups (4) Referring to FIG. 3 , the connection system brings together the top of the column group of the module below (201) with the bottom of the column group from the module above (200), sandwiching the horizontal connection plate (300) between the two groups of columns. The horizontal plate therefore connects all columns in a group together horizontally. Note that 3 of the 4 columns in the groups have been omitted from the figure for clarity.
Referring to FIG. 4 , the top bearing plate (207) is welded to the top of the steel column (201), this plate overhangs inward into the column and acts as a bearing plate for the grout (504) to push against, providing a load path for column tension. It also provides a slightly enlarged area to enable a rabbit to be cut for the rubber seal (302) to be placed within and held securely. The seal (302) ensures wet grout does not leak from the column during the grouting operation. The seal sits inside a small rabbit in the bearing plate so when compressed by the weight of the module above, the rubber is displaced vertically and a steel to steel bearing connection can be made while the seal is in contact with both the top plate (207) and the horizontal connection plate. The connection plate also has a second rubber seal (302)
A plastic grout tube (202) is positioned inside of the column (2) creating a downward delivery path for grout inside the tube, and an upward exit path for the grout in the annulus between the tube and the column wall (203) The top of the grout tube is threaded so an operator can reach down and screw on a matching temporary extension pipe (501) from a grout pump. The tube stops at an elevation lower than the top of the column so that it does not clash with the anchor prong (205) from the column above.
The anchor prong (205) is a steel tube that is connected to the bottom of the grout pipe (202) to continue the delivery path for the grout. It is welded via the gusset plates (204) to the inside of the steel column (200). When the column is in tension, the steel prong transfers tension from the steel column (via the gusset plates) to the prong head (206). The tube also is the means of delivering the wet grout to the connection in a controlled way. (See grouting procedure, FIG. 15 ). The steel gusset plates (204) are welded between the steel column and the Anchor Prong Tube. When the column is in tension these plates act in shear and bending to transfer the tension force from the Anchor prong to the steel wall of the column. When the column is in tension, the steel Prong head (206) pushes upwards against the hard grout fill (504), which in turn pushes against the top plate (207) at the top of the lower column (201). (See load path, FIG. 16 ) Referring to FIG. 5 and FIG. 7 , The horizontal connector plate (300) is a single steel plate with holes and features that locks the columns of different modules in relative lateral position and transfers all lateral forces between the modules. Lateral forces are transferred from the facades (wind) or floor mass (seismic) through the floor and ceiling beams of the modules to the columns, through the grout (504) and then into the horizontal plate. (See FIG. 17 The setting bracket (304), the setting screw (303) and tolerance screw (305) are used by an operator to lock the horizontal plate (300) to the columns below via friction. They are in 4 symmetrical pairs and push against each other when tight. Due to fabrication tolerances and deformations due to transport or thermal etc., the 4 columns below will not be in perfect alignment after installation. The screw connections (305) allow the operator to adjust the horizontal plate (300) into the correct position by lengthening some screws and shortening others. Once in the correct position, all screws can be equally tightened to lock the plate into position. If there is vertical misalignment of the 4 columns below, steel shims of the same shape of the column top plate (207) can be placed between the top of the column below and the horizontal plate bring the horizontal plate back to level.
The guidance nubs (301) are an integral part of the horizontal connector plate (300) and are used to guide the next module above into position as it is lowered on the crane. The tapered guidance fins of the module above (208) will contact these guidance nubs as the module is lowered on the crane and will force the module into the connect position relative to the horizontal connection plate.
The guidance fin plates (208) contact against the guidance nubs (301) to bring the module above into the correct position relative to the horizontal connector plate. The presence and location of fins on each of the 4 corner columns of a module will vary as per the pattern shown in FIG. 9 , this is to ensure the module is guided but not over-constrained. Using this system, the horizontal connector plates can be slightly out of plan tolerance, and the length of the sides of the module can be out of tolerance and the guidance system will still function.
Referring to FIG. 9 , Presence or omittance of pairs of guidance fins creates the three connection sub-types as show in FIG. 9 . The 3 types are: 1) a 2-direction guidance connection that has 2 pairs of guidance fins. 2) a 1 direction guidance connection that has one pair of guidance fins (as shown in FIG. 13 ) 3) a non-guidance type connection that has no guidance fins.
Method of installation is discussed in the following paragraphs.
The foundation, or podium, of the building is typically of conventional construction. At the transition point to modular construction, short stub-columns which are a repeat of the top portion of a column assembly are fixed to the conventional structure in a way that is engineered for the specific forces transferred. Above the foundation the connection embodiment enables cyclical repetitive construction as follows. This description starts at a point where a level of modules has been placed and the connections at their base have been grouted (500), as per FIG. 10 .
Step 1—Survey and Shim. The tops of the columns are surveyed to understand their positional tolerance. Shims are placed on top of the columns as required.
Step 2. The horizontal connector plate (300) is placed on top of the columns and positioned (FIG. 12 ). The setting bracket (304), setting screws (303) and tolerance screws (305) are adjusted while the horizontal connector plate is surveyed into the correct position.
Step 3. The module above is lowered down by crane (FIG. 13 ). The operators need to ensure that the anchor prong (205) of the module hanging on the crane enters the opening at the top of the column, after that the guidance fins (208) will bring the module into the correct position as it is lowered. It should be noted that often this connection cannot be seen or accessed since it is up against the side of another module. The embodiments allow for this operation to occur sight unseen.
Step 4. Once the crane is released, operators can stand on the roof of the module. They can visually inspect down each column via the annulus space (502) (FIG. 14 ). They will then attach a grout pump to the grout tube within a column (501) and pump grout down the tube. They can watch down the column for the grout rising up the annulus space between the grout tube and the wall of the column (502) and stop grouting when it reaches a specified height, just below the point where they connected to the temporary grout tube to the permanent grout tube (500). If the column is accidently over-filled, it can be pumped out again from the same position until the connector for the temporary grout tube is seen above the grout line again. They can then remove the temporary tube (501) and proceed to another column.
Step 5—Repeat Step 1.
Note that since the grout is only required for tension loads in the permanent building that are not present during construction, the grout does not have to have cured before the next module is stacked. The temporary compression forces can be carried via the steel columns alone. The following paragraphs contain a description of the structural load path through the connection. The grout is a key part of the structural load paths. It is the grout that is performing the role that it typically that of bolts and welds in conventional construction. It is the grout (being applied as a liquid) that can manage the tolerance requirements too.
Referring to FIG. 16 , if external forces attempt to pull the modules apart vertically, for example due to loss of column below, or wind overturning forces, force passes from the steel wall of the column above (200), into the steel wall of the column below (201) via the following route through the grouted connection. From the steel wall of the column above (200), the tension force (505) is passed into the anchor prong (205) via the gusset plates (204). The prong head (206) bears against the grout fill (504). The grout fill is put in compression and is confined by all the surrounding steel parts so that it can not break out. The compression force is resisted at the overhang of the top plate (207) of the column below and passes back into the wall of the column below.
Referring to FIG. 17 , if external forces attempt to pull the modules apart horizontally, force passes from the floor diaphragm of one module to the floor diaphragm of the adjacent module via the following route through the grouted connection. The floor system of the modules is connected directly to the column base, most likely via the gusset plates (204), although there are many other means of making that connection to the column base. Horizontal force passes from the column (200) into the gusset plates (204) and into the anchor prong (205) The anchor prong pushes against the cured grout fill (504) which in turn pushes against the horizontal connection plate. The same load path happens in reverse in the adjacent column.
In another embodiment, stiffener plates (601) may be added into the column. These provide additional attachment points to the flanges of beams (602) that can allow for moment continuity between beams and the columns. Without the stiffener plates, the beam webs may still be connected in a shear and axial connection arrangement with less moment resistance. FIG. 18 is a cut-away view of an alternate embodiment where stiffener plates are added through the section of the column to enable welding on of beams allowing for the creation of a rotationally stiff moment connection.
The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others or ordinary skill in the art to understand the embodiments disclosed herein.
When introducing elements of the present disclosure or the embodiments thereof, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. Similarly, the adjective “another,” when used to introduce an element, is intended to mean one or more elements. The terms “including” and “having” are intended to be inclusive such that there may be additional elements other than the listed elements.
Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made only by way of illustration and that numerous changes in the details of construction and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Claims

What is claimed is:

1) A modular building column connection comprising:

a concrete or grout infill inside a composite hollow steel section column;

where the composite hollow steel section column comprises an internal steel protrusion from an upper column to a lower column; and which creates a structural load path for tension and shear between building modules.

2) A modular building column connection comprising:

a concrete or grout infill inside a composite hollow steel section column;

where the composite hollow steel section column comprises an internal steel protrusion from an upper column to a lower column;

a prong; and which creates a structural load path for tension and shear between building modules.

3) A method for a modular unit connection system; comprising

jointing together pre-fabricated rectangular modular building units;

wherein the pre-fabricated rectangular modular building units form a multistory building; and

where the building units can be completely fitted out liquid grout filled columns.

4) The method of claim 3 wherein the need for bolting or welding is eliminated.

5) The method of claim 3 wherein the requirement for access to connections from inside pre-finished building module interiors is eliminated.

6) The modular building column connection of claim 1, wherein the modules are box shaped and contain 4 corner columns.

7) The modular building column connection of claim 6 wherein the 4 corner columns are steel square hollow sections.

8) The modular building connection of claim 1, further comprising structural framing of the modules side walls, floor and ceiling.

9) The modular building connection system of claim 1, further comprising a connector tube passing from the bottom of the columns above and through a horizontal connector plate containing a guidance system and into a top region of the hollow column.

10) The modular building connection system, wherein a system of grouting of the columns from the inside from an access position located on top of an upper most region of the module whereby forming a final positive structural connection.