A heat insulation method for wood structure overhead platform in severe cold region

Abstract

The present application belongs to the field of building technology in severe cold area, and relates to a heat insulation method for wood structure overhead platform in severe cold area, which comprises the following steps: connecting the top end of a foundation (2) located outdoors and embedded in the ground (1) with the bottom end of a wood structure column (3) of a wood structure overhead platform; connecting the upper end of the wood structure column (3) with a wood structure platform beam (4) of the wood structure overhead platform and arranging a wood structure support (5) between adjacent wood structure columns (3) and the wood structure platform beam (4) connected with the adjacent wood structure columns (3); connecting the bottom end of a steel column (6) of a building with the top end of the wood structure column (3); and arranging a heat preservation material (7) on the outer side of the connection between the steel column (6) and the wood structure column (3). The method can achieve good heat insulation effect, and is simple in construction, convenient in transportation and replacement of components.

Description

Technical Field

[0001] This invention belongs to the field of building technology in frigid regions, and relates to a method for heat insulation of elevated buildings in frigid regions, and more particularly to a method for heat insulation of a wooden elevated platform in frigid regions. Background Technology

[0002] For buildings, the column base connects the main load-bearing column to the foundation, transferring the bending moment, axial force, and shear force of the load-bearing column to the foundation. It is a critical node related to structural safety and requires a reliable connection.

[0003] For elevated buildings in permafrost regions, the Arctic and Antarctic, and other frigid areas, heat transfer occurs between the interior and exterior, between the interior and the foundation, and at grounded column bases, because outdoor air and base temperatures are often much lower than indoor operating temperatures. Due to grounding requirements, the column bases penetrate the building's overall insulation. Without effective insulation measures, the insulation effect is reduced when using traditional steel-structured elevated platforms, leading to increased energy consumption, large temperature fluctuations in localized areas, and even condensation and icing.

[0004] Given the technical deficiencies of existing technologies, there is an urgent need for a thermal insulation method suitable for elevated buildings in frigid regions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for heat insulation of wooden elevated platforms in extremely cold regions, which can achieve better heat insulation effects and is simple to construct, easy to transport, and convenient for component replacement.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for heat insulation of a wooden elevated platform in extremely cold regions, characterized by comprising the following steps:

[0008] Connect the top of the outdoor foundation, which is buried in the ground, to the bottom of the wooden columns of the wooden elevated platform.

[0009] The upper end of the wooden structure column is connected to the wooden structure platform beam of the wooden structure elevated platform, and wooden structure supports are set between the adjacent wooden structure columns and the wooden structure platform beams connected to the adjacent wooden structure columns.

[0010] Connect the bottom of the steel column of the building to the top of the wooden column;

[0011] Thermal insulation material is installed on the outside of the connection between the steel column and the wooden structure column.

[0012] Preferably, connecting the bottom end of the steel column of the building to the top end of the wooden column specifically involves: the wooden column having a reserved anchor bolt, the lower end of the steel column having a column base plate inside, the top end of the wooden column being inserted into the bottom end of the steel column and abutting against the column base plate, and the bottom end of the steel column being connected to the top end of the wooden column by the reserved anchor bolt and nut passing through the column base plate.

[0013] Preferably, connecting the bottom end of the steel column of the building to the top end of the wooden column specifically involves: the wooden column being provided with a reserved anchor bolt; the top end of the wooden column being inserted into the lower end of a connecting sleeve with a transverse partition in the middle; the bottom end of the steel column being inserted into the upper end of the connecting sleeve; and the bottom end of the steel column being connected to the top end of the wooden column by the reserved anchor bolt and nut passing through the bottom plate of the steel column and the transverse partition.

[0014] Preferably, connecting the bottom end of the steel column of the building to the top end of the wooden column specifically involves: a cross-shaped steel plate being provided at the bottom end of the steel column and the cross-shaped steel plate being inserted into the top end of the wooden column; and the bottom end of the steel column being connected to the top end of the wooden column by a first connecting bolt that passes laterally through the top end of the wooden column and the cross-shaped steel plate.

[0015] Preferably, the connection between the top of the foundation and the bottom of the wooden column is a rigid connection, a semi-rigid connection, or a hinged connection, and the connection between the wooden platform beam and the wooden column is a hinged connection.

[0016] Preferably, connecting the top of the foundation to the bottom of the wooden column specifically involves: pre-embedding an upward-opening connecting steel sleeve at the top of the foundation; inserting the bottom of the wooden column into the connecting steel sleeve; and connecting the top of the foundation to the bottom of the wooden column by a second connecting bolt passing through the connecting steel sleeve and the bottom of the wooden column.

[0017] Preferably, connecting the top of the foundation to the bottom of the wooden column specifically involves: pre-embedding an upwardly extending cross-shaped connecting plate at the top of the foundation; inserting the cross-shaped connecting plate into the bottom of the wooden column; and connecting the top of the foundation to the bottom of the wooden column via a second connecting bolt passing through the bottom of the wooden column and the cross-shaped connecting plate.

[0018] Preferably, connecting the upper end of the wooden structure column to the wooden structure platform beam of the wooden structure elevated platform specifically involves: a steel connecting plate being provided on the outer side of the upper end of the wooden structure column; the steel connecting plate being connected to the upper end of the wooden structure column by a third connecting bolt passing through the steel connecting plate and the upper end of the wooden structure column; a steel connector being provided on the outer side of the steel connecting plate and the steel connector being inserted into one end of the wooden structure platform beam; and one end of the wooden structure platform beam being connected to the steel connector by a fourth connecting bolt passing through one end of the wooden structure platform beam and the steel connector.

[0019] Preferably, the steel connector is also inserted into one end of the wooden structure support, and the one end of the wooden structure support and the steel connector are connected by a fifth connecting bolt passing through one end of the wooden structure support and the steel connector.

[0020] Preferably, the steel connector and the steel connecting plate are integral.

[0021] Compared with the prior art, the thermal insulation method for wooden elevated platforms in frigid regions of the present invention has one or more of the following beneficial technical effects:

[0022] 1. This invention uses a wooden elevated platform to replace the conventional steel elevated platform. The steel columns of the upper building are connected to the foundation buried in the permafrost through the wooden elevated platform. Since the thermal conductivity of wood is much lower than that of steel, no additional heat insulation material is needed between the steel columns of the upper building and the wooden elevated platform. A good heat insulation effect can be achieved through simple node connection.

[0023] 2. The timber used in the wooden structure elevated platform of this invention is an environmentally friendly material, and the wooden structure elevated platform is a fully assembled structure connected by steel connectors and bolts. All components are prefabricated, and there is no wet work or welding work on site, making construction simple.

[0024] 3. The wooden structure elevated platform used in this invention is more convenient to transport, especially in polar regions, because the density of wood is much lower than that of steel structures.

[0025] 4. The wooden structure elevated platform used in this invention allows for component replacement when necessary due to the assembly nature of the wooden structure connections. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of an elevated building in a frigid region that employs the thermal insulation method for a wooden elevated platform in frigid regions as described in this invention.

[0027] Figure 2 A schematic diagram of the wooden elevated platform used in this invention is shown.

[0028] Figure 3A longitudinal sectional view is shown at the connection between the bottom of a steel column and the top of a wooden column in one connection method.

[0029] Figure 4 A longitudinal sectional view is shown at the connection between the bottom of a steel column and the top of a timber column, using an alternative connection method.

[0030] Figure 5 A longitudinal sectional view is shown at the connection between the bottom of the steel column and the top of the wooden column in another connection method.

[0031] Figure 6 yes Figure 5 AA sectional view.

[0032] Figure 7 A longitudinal sectional view is shown at the connection between the bottom of a timber column and the top of a foundation in one type of connection.

[0033] Figure 8 yes Figure 7 BB cross-sectional view.

[0034] Figure 9 A longitudinal sectional view is shown at the connection between the bottom of a timber column and the top of the foundation, using an alternative connection method.

[0035] Figure 10 yes Figure 9 CC section view.

[0036] Figure 11 A longitudinal sectional view is shown at the connection between the upper end of the timber column and one end of the timber platform beam.

[0037] Figure 12 This illustrates one scenario. Figure 11 DD sectional view.

[0038] Figure 13 This illustrates another scenario. Figure 11 DD sectional view.

[0039] Figure 14 A longitudinal sectional view is shown at the connection point of the upper end of the timber column, one end of the timber platform beam, and one end of the timber support. Detailed Implementation

[0040] Before detailing any embodiment of the invention, it should be understood that the invention, in its application, is not limited to the details of the construction and arrangement of the components set forth in the following description or illustrated in the following figures. The invention can have other embodiments and can be practiced or carried out in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The use of “comprising” or “having” and variations thereof is intended to cover the items set forth below and their equivalents, as well as any additional items. Unless otherwise specified or limited, the terms “installation,” “connection,” “support,” and “linkage,” and variations thereof are used broadly and cover both direct and indirect installation, connection, support, and linking. Moreover, “connection” and “linkage” are not limited to physical or mechanical connections or links.

[0041] Furthermore, firstly, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention. Secondly, the term "a" should be understood as "at least one" or "one or more," that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple. The term "a" should not be construed as a limitation on the quantity.

[0042] In this invention, a wooden elevated platform replaces the conventional steel elevated platform, and the steel columns 6 of the upper building are connected to the foundation 2 buried in permafrost via the wooden elevated platform. For example, Figure 1 and 2 As shown, the timber-framed elevated platform includes timber columns 3, timber platform beams 4, and timber supports 5. The timber-framed elevated platform can be made of oak, mahogany, birch, red oak, hard maple, alder, beech, boxwood, etc., which are dense, hard, and have strong load-bearing capacity.

[0043] The upper structure, via a simple node connection to the wooden elevated platform, provides thermal insulation at the base of the steel columns, while the upper load is reliably transferred to the foundation 2 through the wooden elevated platform. The connection between the wooden columns 3 and the foundation 2 can be rigid, semi-rigid, or hinged. The connection between the wooden platform beam 4 and the wooden columns 3 can be hinged, forming a lateral force resisting system through the addition of bidirectional wooden supports 5. The number of wooden supports 5 can be adjusted according to the actual layout. The vertical load from the upper structure is borne by the wooden columns 3, and the horizontal load is borne by the wooden supports 5.

[0044] The following is for reference. Figure 1-2 This invention provides a detailed description of the method for heat insulation of a wooden elevated platform in frigid regions. The method includes the following steps:

[0045] S1: Connect the top of the foundation 2, which is located outdoors and buried in the ground 1, to the bottom of the wooden column 3 of the wooden structure platform.

[0046] In this invention, the foundation 2 can be pre-embedded in the ground (e.g., permafrost) 1. Preferably, the foundation 2 is a concrete foundation, which serves a supporting function. Meanwhile, the connection between the top of the foundation 2 and the bottom of the wooden column 3 can be a rigid connection, a semi-rigid connection, or a hinged connection.

[0047] like Figure 7 and 8 As shown, when using a rigid or semi-rigid connection, a connecting steel sleeve 15 with an upward opening is pre-embedded at the top of the foundation 2. The connecting steel sleeve 15 is U-shaped, and the bottom end of the wooden structure column 3 is inserted into the connecting steel sleeve 15. The top end of the foundation 2 is connected to the bottom end of the wooden structure column 3 by a second connecting bolt 16 passing through the connecting steel sleeve 15 and the bottom end of the wooden structure column 3.

[0048] like Figure 9 and 10 As shown, when using a hinged connection, a cross-shaped connecting plate 17 extending upwards is pre-embedded at the top of the foundation 2. The cross-shaped connecting plate 17 is inserted into the bottom of the wooden column 3. The top of the foundation 2 is connected to the bottom of the wooden column 3 by a second connecting bolt 16 passing through the bottom of the wooden column 3 and the cross-shaped connecting plate 17.

[0049] S2: Connect the upper end of the wooden structure column 3 to the wooden structure platform beam 4 of the wooden structure elevated platform, and set up a wooden structure support 5 between the adjacent wooden structure columns 3 and the wooden structure platform beam 4 connected to the adjacent wooden structure columns 3.

[0050] In this invention, the connection between the wooden platform beam 4 and the wooden column 3 can be a hinged connection. Specifically, as shown in the figure... Figure 11-13As shown, a steel connecting plate 18 is provided on the outer side of the upper end of the wooden structure column 3. Alternatively, a U-shaped steel connecting sleeve can be directly fitted onto the outer side of the upper end of the wooden structure column 3. The steel connecting plate 18 is connected to the upper end of the wooden structure column 3 by a third connecting bolt 19 passing through the steel connecting plate 18 and the upper end of the wooden structure column 3. Simultaneously, a steel connector 21 is provided on the outer side of the steel connecting plate 18. The steel connector 21 is inserted into one end of the wooden structure platform beam 4. One end of the wooden structure platform beam 4 is connected to the steel connector 21 by a fourth connecting bolt 20 passing through one end of the wooden structure platform beam 4 and the steel connector 21. Thus, the connection between the upper end of the wooden structure column 3 and one end of the wooden structure platform beam 4 is achieved.

[0051] Among them, such as Figure 12 As shown, when all four sides of the wooden structure column 3 need to be connected to the wooden structure platform beam 4, a steel connector 21 is provided on each of the four sides of the steel connecting plate 18. One steel connector 21 is inserted into one end of each of the four wooden structure platform beams 4. This achieves the connection between the four wooden structure platform beams 4 and the wooden structure column 3.

[0052] like Figure 13 As shown, when the wooden column 3 only needs to be connected to the wooden platform beam 4 on both sides, only one steel connector 21 needs to be provided on each side of the steel connecting plate 18. One steel connector 21 is inserted into one end of each of the two wooden platform beams 4. This achieves the connection between the two wooden platform beams 4 and the wooden column 3.

[0053] At the location where the wooden structure support 5 is installed, in order to achieve the connection between the wooden structure support 5 and the wooden structure column 3 and the wooden structure platform beam 4, as follows: Figure 14 As shown, the steel connector 21 can be enlarged and extended beyond the wooden platform beam 4. The enlarged portion of the steel connector 21 extending beyond the wooden platform beam 4 is inserted into one end of the wooden support 5. One end of the wooden support 5 is connected to the steel connector 21 by a fifth connecting bolt 22 passing through one end of the wooden support 5 and the steel connector 21. This achieves the connection between the wooden support 5 and the wooden column 3 and the wooden platform beam 4.

[0054] In this invention, preferably, the steel connector 21 and the steel connecting plate 18 are integrally formed. This enhances the connection strength and reduces some connection operations.

[0055] S3: Connect the bottom end of the steel column 6 of the building to the top end of the wooden structure column 3.

[0056] In this invention, the connection between the bottom end of the steel column 6 and the top end of the wooden column 3 of the building can be achieved in a variety of different ways.

[0057] in, Figure 3 A longitudinal sectional view is shown at the connection point between the bottom of a steel column and the top of a timber column, illustrating one possible connection method. (See attached image.) Figure 3 As shown, the wooden column 3 is equipped with pre-installed anchor bolts 9. The steel column 6 is connected to the lower steel beam 8 of the building, and its lower end extends out of the building from the lower steel beam 8. The lower end of the steel column 6 is provided with a column base plate 11, and the column base plate 11 is a certain distance away from the very end of the steel column 6. Thus, the top end of the wooden column 3 can be inserted into the bottom end of the steel column 6 and abut against the column base plate 11. Then, the bottom end of the steel column 6 is connected to the top end of the wooden column 3 by the pre-installed anchor bolts 9 and nuts passing through the column base plate 11.

[0058] Figure 4 A longitudinal sectional view is shown at the connection point between the bottom of a steel column and the top of a timber column, illustrating an alternative connection method. (See attached image.) Figure 4 As shown, the bottom end of the steel column 6 is connected to the top end of the wooden structure column 3 via a connecting steel sleeve 12 with a transverse partition in the middle. The wooden structure column 3 is equipped with pre-installed anchor bolts 9. The steel column 6 is connected to the lower steel beam 8 of the building, and its lower end extends out of the building from the lower steel beam 8. The steel column 6 has a base plate at its very end. The top end of the wooden structure column 3 is inserted into the lower end of the connecting steel sleeve 12 with the transverse partition in the middle and abuts against the lower surface of the transverse partition. The bottom end of the steel column 6 is inserted into the upper end of the connecting steel sleeve 12 and abuts against the upper surface of the transverse partition. The bottom end of the steel column 6 is connected to the top end of the wooden structure column 3 by the pre-installed anchor bolts 9 and nuts 10 passing through the base plate of the steel column 6 and the transverse partition.

[0059] Figure 5 This shows a longitudinal sectional view of the connection between the bottom of a steel column and the top of a timber column, representing another type of connection. (See attached image.) Figure 5 and 6 As shown, the steel column 6 is connected to the lower steel beam 8 of the building, and its bottom end is flush with the lower steel beam 8. A cross-shaped steel plate 13 is provided at the bottom end of the steel column 6, and the cross-shaped steel plate 13 extends outside the building. The cross-shaped steel plate 13 is inserted into the top of the wooden structure column 3. The bottom end of the steel column 6 is connected to the top end of the wooden structure column 3 by a first connecting bolt 14 that passes laterally through the top end of the wooden structure column 3 and the cross-shaped steel plate 13.

[0060] Since the thermal conductivity of wood is much lower than that of steel, wood can be used as a heat insulation material. In this invention, no additional heat insulation material is needed between the steel column 6 and the wooden column 3, that is, at the traditional column base, making the connection of the heat insulation node simpler.

[0061] S4: Thermal insulation material 7 is installed on the outside of the connection between the steel column 6 and the wooden structure column 3.

[0062] By incorporating the insulation material 7, heat transfer between the steel column 6 and the outdoor atmosphere can be reduced, further ensuring the insulation effect.

[0063] As described above, in this invention, the entire construction process uses steel connectors and bolts for connection, resulting in a fully prefabricated structure. All components are prefabricated, eliminating any wet work or welding on-site, simplifying construction. Furthermore, since wood has a much lower density than steel structures, it is particularly convenient for transport, especially in polar regions. Moreover, due to the "assembly" nature of the wood structure connections, components can be replaced when necessary.

[0064] To demonstrate the effectiveness of the thermal insulation method for wooden elevated platforms in frigid regions, as described in this invention, the inventors... Figure 3 Taking the connection method shown as an example, the insulation effect of the wooden structure elevated platform insulation method for cold regions according to the present invention and the method without the present invention (i.e., using a traditional steel structure elevated platform) were calculated. The calculation mainly compared the heat transfer differences between the wooden structure elevated platform of the present invention and the traditional steel structure elevated platform (neither with other insulation measures) under the same indoor and outdoor environment and the same cross-sectional dimensions. The various dimensions of the steel column 6, the height of the connection section, and the comprehensive calculation results are shown in the table below.

[0065]

[0066] As shown in the table above, under the same conditions, the heat transfer of a steel structure platform is 152.05W, while that of a wooden structure platform is 5.65W, making the steel structure platform approximately 26.9 times more efficient than the wooden structure platform. Therefore, the thermal insulation method for wooden elevated platforms in frigid regions using this invention eliminates the need for additional insulation materials between the steel columns of the upper building and the wooden elevated platform; a good thermal insulation effect can be achieved through simple node connections.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention based on the concept of the present invention, without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for heat insulation of a wooden elevated platform in extremely cold regions, characterized in that, Includes the following steps: The top of the foundation (2) located outdoors and buried in the ground (1) is connected to the bottom of the wooden column (3) of the wooden structure platform; the connection between the top of the foundation (2) and the bottom of the wooden column (3) is in the form of rigid connection, semi-rigid connection or hinged connection. The upper end of the wooden structure column (3) is connected to the wooden structure platform beam (4) of the wooden structure elevated platform, and a wooden structure support (5) is set between the adjacent wooden structure column (3) and the wooden structure platform beam (4) connected to the adjacent wooden structure column (3). The connection between the wooden structure platform beam (4) and the wooden structure column (3) is a hinged connection. Connect the bottom end of the steel column (6) of the building to the top end of the wooden column (3); Thermal insulation material (7) is provided on the outside of the connection between the steel column (6) and the wooden column (3); Specifically, connecting the bottom end of the steel column (6) of the building to the top end of the wooden column (3) involves: the wooden column (3) being provided with a reserved anchor bolt (9), the lower end of the steel column (6) being provided with a column base plate (11), the top end of the wooden column (3) being inserted into the bottom end of the steel column (6) and abutting against the column base plate (11), and the bottom end of the steel column (6) being connected to the top end of the wooden column (3) by the reserved anchor bolt (9) and nut (10) passing through the column base plate (11); Alternatively, the bottom end of the steel column (6) of the building is connected to the top end of the wooden column (3) in the following ways: the wooden column (3) is provided with a reserved anchor bolt (9), the top end of the wooden column (3) is inserted into the lower end of the connecting sleeve (12) with a transverse partition in the middle, the bottom end of the steel column (6) is inserted into the upper end of the connecting sleeve (12), and the bottom end of the steel column (6) is connected to the top end of the wooden column (3) by the reserved anchor bolt (9) and nut (10) passing through the bottom plate of the steel column (6) and the transverse partition; Alternatively, the bottom end of the steel column (6) of the building is connected to the top end of the wooden column (3) by: a cross steel plate (13) is provided at the bottom end of the steel column (6) and the cross steel plate (13) is inserted into the top end of the wooden column (3), and the bottom end of the steel column (6) is connected to the top end of the wooden column (3) by a first connecting bolt (14) that passes laterally through the top end of the wooden column (3) and the cross steel plate (13).

2. The heat insulation method for a wooden elevated platform in frigid regions according to claim 1, characterized in that, Specifically, connecting the top of the foundation (2) to the bottom of the wooden column (3) involves: in rigid connection or semi-rigid connection, the top of the foundation (2) is pre-embedded with an upward-opening connecting steel sleeve (15), the bottom of the wooden column (3) is inserted into the connecting steel sleeve (15), and the top of the foundation (2) is connected to the bottom of the wooden column (3) by a second connecting bolt (16) passing through the connecting steel sleeve (15) and the bottom of the wooden column (3).

3. The heat insulation method for a wooden elevated platform in frigid regions according to claim 1, characterized in that, Specifically, connecting the top of the foundation (2) to the bottom of the wooden column (3) involves: when hinged, the top of the foundation (2) is pre-embedded with an upwardly extending cross connecting plate (17), the cross connecting plate (17) is inserted into the bottom of the wooden column (3), and the top of the foundation (2) is connected to the bottom of the wooden column (3) by a second connecting bolt (16) passing through the bottom of the wooden column (3) and the cross connecting plate (17).

4. The heat insulation method for a wooden elevated platform in frigid regions according to claim 1, characterized in that, The connection between the upper end of the wooden structure column (3) and the wooden structure platform beam (4) of the wooden structure elevated platform is specifically as follows: a steel connecting plate (18) is provided on the outer side of the upper end of the wooden structure column (3). The steel connecting plate (18) is connected to the upper end of the wooden structure column (3) by a third connecting bolt (19) passing through the steel connecting plate (18) and the upper end of the wooden structure column (3). A steel connector (21) is provided on the outer side of the steel connecting plate (18) and the steel connector (21) is inserted into one end of the wooden structure platform beam (4). One end of the wooden structure platform beam (4) is connected to the steel connector (21) by a fourth connecting bolt (20) passing through one end of the wooden structure platform beam (4) and the steel connector (21).

5. The heat insulation method for a wooden elevated platform in frigid regions according to claim 4, characterized in that, The steel connector (21) is also inserted into one end of the wooden structure support (5), and the one end of the wooden structure support (5) and the steel connector (21) are connected by the fifth connecting bolt (22) passing through one end of the wooden structure support (5) and the steel connector (21).

6. The heat insulation method for a wooden elevated platform in frigid regions according to claim 5, characterized in that, The steel connector (21) and the steel connector plate (18) are integral.

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