A portal steel frame structure deformed I-beam reinforcing structure

Abstract

This utility model provides a reinforcement structure for deformable I-beams in portal steel frame structures. By setting a first reinforcement structure in the deformed section of the deformable I-beam body and a second reinforcement structure in the non-deformed section, only the deformed and non-deformed sections need to be locally reinforced, eliminating the need for full-span reinforcement and overall support. The building can continue to operate normally. Physical reinforcement replaces thermal straightening. The first and second reinforcement structures are located below the upper flange of the I-beam, and the reinforcement work is carried out at the bottom of the beam, eliminating the need to replace the maintenance structure. This solves the technical problems of existing technologies, such as the difficulty or low effectiveness of in-situ thermal straightening, the need to remove associated maintenance structures for replacement work, the need to shut down the existing building during construction, the need for overall support scheme demonstration for partial demolition of the building, large associated surfaces, construction difficulties, and high costs associated with traditional methods of increasing the cross-section, which require full-span reinforcement.

Description

Technical Field

[0001] This utility model belongs to the field of deformable steel beam reinforcement technology, and specifically relates to a reinforcement structure for deformable I-beams in portal steel frame structures. Background Technology

[0002] Portal frame structures are a common type of steel structure, widely used in various industrial and civil buildings due to their rational stress distribution, convenient construction, and economical cost. These include single-story factories, industrial warehouses and logistics centers, exhibition halls, car dealerships, farmers' markets, shopping malls, supermarkets, stadiums, auditoriums, train station waiting halls, and farms. However, existing portal frame structures may experience defects such as excessive deformation, localized buckling, and fatigue damage in the steel components over long-term use due to factors such as impacts from machinery and poor construction quality.

[0003] I-beams are a commonly used type of steel beam in portal frames. For torsional I-beams, the standard requires that "hot working methods can be used for correction; when correction is difficult, replacement or reinforcement should be carried out." However, for severely tortuous steel components, in-situ hot working correction is difficult to implement or has low effectiveness. Replacement work requires the removal of related supporting structures (such as roof panels, purlins, tie rods, etc.), and the existing building must be shut down during construction. Furthermore, a comprehensive support scheme must be demonstrated for the partial demolition of the building. This involves a large associated area, making construction difficult and challenging. Traditional methods of increasing the cross-section require full-span reinforcement, which is costly. Utility Model Content

[0004] The purpose of this utility model is to provide a reinforcement structure for deformable I-beams in portal steel frame structures, thereby overcoming the technical problems existing in the prior art and completing the reinforcement and maintenance of the tortuous and deformed I-beams without removing them. The specific technical solution is as follows:

[0005] A portal steel frame structure deformation I-beam reinforcement structure includes a deformation I-beam body, the deformation I-beam body includes a reinforced beam segment and an unreinforced beam segment, the reinforced beam segment includes a deformation segment and an undeformed segment extending outward from opposite ends of the deformation segment;

[0006] A first reinforcing structure is provided on the deformable section. The first reinforcing structure includes a first newly added upper flange, a first newly added lower flange, a first newly added vertical web, a newly added inclined web, and a first lower flange connecting plate. The first newly added upper flange is located below the upper flange of the steel beam of the deformable section and is distributed on both sides of the web of the steel beam of the deformable section. The first newly added lower flange is located below the lower flange of the steel beam of the deformable section and is parallel to the upper flange of the steel beam of the deformable section. One end of the first newly added vertical web is welded to the bottom surface of the first newly added upper flange and the other end is welded to the top surface of the first newly added lower flange. One end of the newly added inclined web is welded to the bottom surface of the first newly added upper flange on the other side and the other end is welded to the top surface of the first newly added lower flange. One end of the first lower flange connecting plate is connected to the bottom surface of the lower flange of the steel beam of the deformable section and the other end is connected to the top surface of the first newly added lower flange.

[0007] The first reinforcing structure further includes a first stiffening plate and a second stiffening plate of the deformable section. The first stiffening plate of the deformable section is located on the side where the first newly added vertical web is provided. The adjacent sides of the first stiffening plate of the deformable section are respectively connected to the upper flange, web, lower flange and the first newly added lower flange of the steel beam of the deformable section. The second stiffening plate of the deformable section is located on the side where the newly added inclined web is provided. The adjacent sides of the second stiffening plate of the deformable section are respectively connected to the upper flange, web and lower flange of the steel beam of the deformable section.

[0008] Preferably, an installation plate extends from the side of the first stiffening plate of the deformed section, and an additional tie rod is installed on the installation plate by installation bolts. The other end of the additional tie rod is connected to a stiffening plate on an adjacent span steel beam by the installation bolts.

[0009] Preferably, a second reinforcing structure is provided on the undeformed section. The second reinforcing structure includes a second additional upper flange, a second additional lower flange, and a second additional vertical web. The second additional upper flange is located below the upper flange of the steel beam in the undeformed section and is distributed on both sides of the web of the steel beam in the undeformed section. The second additional lower flange is located below the lower flange of the steel beam in the undeformed section. One end of the second additional vertical web is welded to the second additional upper flange, and the other end is welded to the second additional lower flange.

[0010] Preferably, the second reinforcing structure further includes a first stiffening plate and a second stiffening plate of the undeformed section, wherein the three adjacent sides of the first stiffening plate and the second stiffening plate of the undeformed section are respectively connected to the upper flange, web and lower flange of the steel beam of the undeformed section.

[0011] Preferably, the beam span area extending 500mm outward from both ends of the deformed segment is the undeformed segment.

[0012] Preferably, the first stiffening plate and the second stiffening plate of the deformable segment are evenly distributed at intervals of 500 mm.

[0013] Preferably, the first stiffening plate of the undeformed segment is spaced 500mm apart from the first stiffening plate of the adjacent deformed segment, and the second stiffening plate of the undeformed segment is spaced 500mm apart from the second stiffening plate of the adjacent deformed segment.

[0014] Preferably, the contour formed by the side surface where the first stiffening plate of the deformable segment connects to the deformable segment is the same as the deformation contour of the deformable segment used to install the first stiffening plate of the deformable segment.

[0015] Preferably, the contour formed by the side surface where the second stiffening plate of the deformable segment connects to the deformable segment is the same as the deformation contour of the deformable segment used to install the second stiffening plate.

[0016] Preferably, the first and second reinforcing structures are made of carbon structural steel.

[0017] Compared with existing technologies, this utility model has the following beneficial effects:

[0018] 1. The present invention provides a portal steel frame structure deformation I-beam reinforcement structure, which achieves reinforcement without dismantling the deformation section by setting a first reinforcement structure adapted to the torsional shape in the deformation section of the deformation I-beam body.

[0019] 2. The reinforcement structure provided by this utility model can complete the local reinforcement of the deformed section and the undeformed section extending outward from the deformed section by setting a second reinforcement structure in the undeformed section. It does not require full span reinforcement, so no overall support is needed and the building can continue to operate normally.

[0020] 3. This utility model uses a physical reinforcement method to replace thermal straightening. The first and second reinforcement structures are both located below the upper flange of the I-beam, meaning that the reinforcement work is only carried out at the bottom of the beam and there is no need to dismantle or replace the maintenance structure.

[0021] 4. This utility model features multiple reinforcement lines, resulting in a high degree of structural safety redundancy. Specifically, this includes: increasing the cross-section of the deformed section of the steel beam to enhance its stiffness and load-bearing capacity; and adding tie rods to increase lateral support, thereby improving the steel beam's torsional bearing capacity and out-of-plane stability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale.

[0023] Figure 1 This is an elevation view of the deformed I-beam body of this utility model.

[0024] Figure 2 This is a cross-sectional view of the deformed section in this utility model.

[0025] Figure 3 This is a schematic diagram of the deformable section in this utility model.

[0026] Figure 4 This is a schematic diagram of the undeformed section of the present invention.

[0027] Figure 5 This is a cross-sectional view of the added tie rod in the deformed section of this utility model.

[0028] Explanation of key figure labels:

[0029] 10-Deformed I-beam body, 20-Deformed section, 21-First newly added upper flange, 22-First newly added lower flange, 23-First newly added vertical web, 24-Newly added inclined web, 25-First lower flange connecting plate, 26-First stiffening plate of deformed section, 27-Second stiffening plate of deformed section, 28-Newly added tie rod, 30-Undeformed section, 31-Second newly added upper flange, 32-Second newly added lower flange, 33-Second newly added vertical web, 34-First stiffening plate of undeformed section, 35-Second stiffening plate of undeformed section. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] In the description of this utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0032] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If the terms "first," "second," and "third" are used in the description, they are for descriptive purposes and to distinguish technical features, and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. The embodiments of this utility model will now be described based on its overall structure.

[0034] Example

[0035] like Figures 1 to 5 As shown, this utility model embodiment provides a portal steel frame structure deformable I-beam reinforcement structure, including a deformable I-beam body 10. The deformable I-beam body 10 includes a reinforced beam segment and an unreinforced beam segment. The reinforced beam segment includes a deformable segment 20 and an undeformed segment 30 located at opposite ends of the deformable segment 20 extending outward by 500mm (i.e., the beam span area of ​​the deformable segment 20 extending outward by 500mm from opposite ends is the undeformed segment 30).

[0036] Preferably, the deformable segment 20 is provided with a first reinforcing structure, which includes a first newly added upper flange 21, a first newly added lower flange 22, a first newly added vertical web 23, a newly added inclined web 24, and a first lower flange connecting plate 25. The first newly added upper flange 21 is located below the upper flange of the steel beam of the deformable segment 20 and is fixedly welded to the upper flange. The first newly added upper flange 21 is distributed on both sides of the web of the steel beam of the deformable segment 20. The first newly added lower flange 22 is located below the lower flange of the steel beam of the deformable segment 20 and is fixedly welded to the lower flange. The first newly added lower flange 22 is parallel to the upper flange of the steel beam of the deformable segment 20. One end of a newly added vertical web 23 is welded to the bottom surface of the first newly added upper flange 21, and the other end is welded to the top surface of the first newly added lower flange 22. One end of a newly added inclined web 24 is welded to the bottom surface of the first newly added upper flange 21 on the other side, and the other end is welded to the top surface of the first newly added lower flange 22. One end of the first lower flange connecting plate 25 is connected to the bottom surface of the lower flange of the steel beam of the deformed section 20, and the other end is connected to the top surface of the first newly added lower flange 22. The first lower flange connecting plate 25 is used to support the lower flange of the steel beam of the deformed section 20 after deformation. The first lower flange connecting plate 25 and the lower flange of the steel beam of the deformed section 20 are connected by a slit weld.

[0037] The first newly added upper flange 21, the first newly added lower flange 22, the first newly added vertical web 23, the newly added inclined web 24, and the first lower flange connecting plate 25 form a box-type first reinforcement structure, which increases the cross-sectional area of ​​the deformed section 20 of the deformable I-beam body 10 and improves the bearing capacity and stiffness of the deformed section 20 of the deformable I-beam body 10. At the same time, the first reinforcement structure is located at the bottom of the upper flange of the I-beam, so that the addition of the first reinforcement structure can be implemented at the bottom of the beam without the need to replace the maintenance structure.

[0038] In some preferred embodiments, the first reinforcing structure further includes a first stiffening plate 26 and a second stiffening plate 27 of the deformable segment. The first stiffening plate 26 is located on the side where the first newly added vertical web 23 is provided. Adjacent edges of the first stiffening plate 26 are connected to the upper flange, web, lower flange, and first newly added lower flange 22 of the steel beam of the deformable segment 20, respectively. Notably, the contour formed by the edges of the first stiffening plate 26 connecting to the deformable segment 20 is the same as the deformation contour of the deformable segment 20 used to install the first stiffening plate 26. In simpler terms, the contour formed by the edges of the first stiffening plate 26 used for connection matches the deformation contour of the desired installation location. The first stiffening plate 26 and the deformable segment 20 are connected by welding.

[0039] Furthermore, the second stiffening plate 27 of the deformable segment is located on the side where the newly added inclined web 24 is provided. The adjacent edges of the second stiffening plate 27 are connected to the upper flange, web, and lower flange of the steel beam of the deformable segment 20, respectively. The contour formed by the edges of the second stiffening plate 27 connected to the deformable segment 20 is the same as the deformation contour of the deformable segment 20 used to install the second stiffening plate 27. Similarly, the contour formed by the edges of the second stiffening plate 27 used for connection is adapted to the deformation contour of the desired installation location. The second stiffening plate 27 and the deformable segment 20 are connected by welding.

[0040] In summary, the connecting surfaces of the first stiffening plate 26 and the second stiffening plate 27 of the deformable segment are designed according to the actual deformation profile of the deformable segment 20.

[0041] In some preferred embodiments, a mounting plate extends from the side of the first stiffening plate 26 of the deformable segment. An additional tie rod 28 is mounted on the mounting plate via mounting bolts. The other end of the additional tie rod 28 is connected to a stiffening plate on an adjacent span steel beam via the mounting bolts. The additional tie rod 28 further reinforces the deformable segment 20.

[0042] Preferably, a second reinforcing structure is provided on the undeformed segment 30. The second reinforcing structure includes a second additional upper flange 31, a second additional lower flange 32, and a second additional vertical web 33. The second additional upper flange 31 is located below the upper flange of the steel beam of the undeformed segment 30 and is distributed on both sides of the web of the steel beam of the undeformed segment 30. The second additional lower flange 32 is located below the lower flange of the steel beam of the undeformed segment 30. One end of the second additional vertical web 33 is welded to the second additional upper flange 31, and the other end is welded to the second additional lower flange 32.

[0043] The second newly added upper flange 31, the second newly added lower flange 32, and the two second newly added vertical webs 33 form a box-type second reinforcement structure, which increases the cross-sectional area of ​​the undeformed section 30 of the deformed I-beam body 10, and improves the load-bearing capacity and stiffness of the undeformed section 30 of the deformed I-beam body 10. At the same time, the second reinforcement structure is set in the undeformed section 30 as a stiffness transition zone between the deformed section 20 and the unreinforced beam section, reducing the risk of stress concentration. Meanwhile, the first reinforcement structure is located at the bottom of the upper flange of the I-beam, so that the addition of the first reinforcement structure can be implemented at the bottom of the beam without the need to replace the maintenance structure.

[0044] In some preferred embodiments, the second reinforcing structure further includes a first stiffening plate 34 and a second stiffening plate 35 of the undeformed section, wherein the three adjacent sides of the first stiffening plate 34 and the second stiffening plate 35 of the undeformed section are respectively welded to the upper flange, web and lower flange of the steel beam of the undeformed section 30.

[0045] In some preferred embodiments, the beam span area extending 500 mm outward from both ends of the deformable segment 20 is the undeformed segment 30. The first stiffening plate 26 and the second stiffening plate 27 of the deformable segment 20 are evenly distributed at 500 mm intervals. The first stiffening plate 34 of the undeformed segment is 500 mm apart from its adjacent first stiffening plate 26 of the deformable segment, and the second stiffening plate 35 of the undeformed segment is 500 mm apart from its adjacent second stiffening plate 27 of the deformable segment.

[0046] In some preferred embodiments, the first and second reinforcing structures are made of carbon structural steel.

[0047] In some other embodiments, the width of the first newly added lower flange 22 is defined as L. When L≥400mm, the first reinforcing structure further includes a second lower flange connecting plate. The second lower flange connecting plate is located directly below the web of the I-beam of the deformed segment 20. Its top end is connected to the lower flange of the I-beam, and its bottom end is connected to the second newly added lower flange 32.

[0048] Specifically, the second lower flange connecting plate is similar to the first lower flange connecting plate. Its top end is welded to the lower flange section of the I-beam, and its bottom end is welded to the second newly added lower flange 32. By setting the second lower flange connecting plate, the welding stability between the second newly added lower flange 32 and the lower flange of the I-beam is improved, and the stress on a single weld is reduced.

[0049] In some other embodiments, the width of the second additional lower wing plate 32 is defined as W. When W ≥ 400 mm, a stress relief slit is provided in the middle of the second additional lower wing plate 32 along its length direction.

[0050] When W≥400mm, a stress-relieving slit not less than 80% of the length of the second newly added lower flange 32 is opened in the middle of the width direction of the second newly added lower flange 32 along its length direction, and welding is performed on both sides of the stress-relieving slit to ensure the connection stability between the second newly added lower flange 32 and the lower flange of the I-beam of the undeformed section 30, while reducing the stress of a single weld.

[0051] In summary, this utility model provides a reinforcement structure for deformable I-beams in a portal frame structure. By setting a first reinforcement structure adapted to the torsional shape in the deformed section of the deformed I-beam, reinforcement can be completed without dismantling the deformed section. The reinforcement structure provided by this utility model, by setting a second reinforcement structure in the undeformed section, can locally reinforce both the deformed section and the undeformed section extending outwards from it, without requiring full-span reinforcement. Therefore, no overall support is needed, and the building can continue to operate normally. This utility model uses physical reinforcement methods instead of thermal straightening. Both the first and second reinforcement structures are located below the upper flange of the I-beam, meaning the reinforcement work is only carried out at the bottom of the beam, without the need to replace or replace the maintenance structure. This utility model sets up multiple reinforcement lines, resulting in high structural safety redundancy. Specifically, this includes: increasing the cross-section of the deformed section of the steel beam to improve the original beam stiffness and load-bearing capacity; and adding tie rods to increase lateral support of the steel beam, improving its torsional bearing capacity and out-of-plane stability.

[0052] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it is obvious that many changes and variations can be made based on the above teachings. Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of the present invention and are protected by patent law.

Claims

1. A portal frame steel structure deformable I-beam reinforcement structure, comprising a deformable I-beam body (10), wherein the deformable I-beam body (10) comprises reinforced beam segments and unreinforced beam segments, characterized in that, The reinforced beam segment includes a deformable segment (20) and an undeformed segment (30) extending outward from opposite ends of the deformable segment (20); The deformable segment (20) is provided with a first reinforcing structure, which includes a first newly added upper flange (21), a first newly added lower flange (22), a first newly added vertical web (23), a newly added inclined web (24), and a first lower flange connecting plate (25). The first newly added upper flange (21) is located below the upper flange of the steel beam of the deformable segment (20) and is distributed on both sides of the web of the steel beam of the deformable segment (20). The first newly added lower flange (22) is located below the lower flange of the steel beam of the deformable segment (20) and is connected to the first lower flange connecting plate (25). The upper flange of the steel beam of the deformed section (20) is parallel. One end of the first newly added vertical web (23) is welded to the bottom surface of the first newly added upper flange (21), and the other end is welded to the top surface of the first newly added lower flange (22). One end of the newly added inclined web (24) is welded to the bottom surface of the first newly added upper flange (21) on the other side, and the other end is welded to the top surface of the first newly added lower flange (22). One end of the first lower flange connecting plate (25) is connected to the bottom surface of the lower flange of the steel beam of the deformed section (20), and the other end is connected to the top surface of the first newly added lower flange (22). The first reinforcement structure also includes a first stiffening plate (26) and a second stiffening plate (27) of the deformation section. The first stiffening plate (26) of the deformation section is located on the side where the first newly added vertical web (23) is provided. The adjacent side surfaces of the first stiffening plate (26) of the deformation section are respectively connected to the upper flange, web, lower flange and the first newly added lower flange (22) of the steel beam of the deformation section (20). The second stiffening plate (27) of the deformation section is located on the side where the newly added inclined web (24) is provided. The adjacent side surfaces of the second stiffening plate (27) of the deformation section are respectively connected to the upper flange, web and lower flange of the steel beam of the deformation section (20).

2. The portal steel frame structure deformable I-beam reinforcement structure according to claim 1, characterized in that, An installation plate extends from the side of the first stiffening plate (26) of the deformed section. A new tie rod (28) is installed on the installation plate by means of installation bolts. The other end of the new tie rod (28) is connected to the stiffening plate on the adjacent span steel beam by means of the installation bolts.

3. The portal steel frame structure deformable I-beam reinforcement structure according to claim 2, characterized in that, A second reinforcing structure is provided on the undeformed section (30). The second reinforcing structure includes a second newly added upper flange (31), a second newly added lower flange (32), and a second newly added vertical web (33). The second newly added upper flange (31) is located below the upper flange of the steel beam of the undeformed section (30) and is distributed on both sides of the web of the steel beam of the undeformed section (30). The second newly added lower flange (32) is located below the lower flange of the steel beam of the undeformed section (30). One end of the second newly added vertical web (33) is welded to the second newly added upper flange (31), and the other end is welded to the second newly added lower flange (32).

4. The portal steel frame structure deformable I-beam reinforcement structure according to claim 3, characterized in that, The second reinforcement structure also includes a first stiffening plate (34) of the undeformed section and a second stiffening plate (35) of the undeformed section. The three adjacent sides of the first stiffening plate (34) of the undeformed section and the second stiffening plate (35) of the undeformed section are respectively connected to the upper flange, web and lower flange of the steel beam of the undeformed section (30).

5. The portal steel frame structure deformable I-beam reinforcement structure according to claim 1, characterized in that, The beam span area that extends 500mm outward from both ends of the deformed segment (20) is the undeformed segment (30).

6. The portal steel frame structure deformable I-beam reinforcement structure according to claim 4, characterized in that, The first stiffening plate (26) and the second stiffening plate (27) of the deformable segment (20) are evenly distributed at intervals of 500 mm.

7. The portal steel frame structure deformable I-beam reinforcement structure according to claim 6, characterized in that, The first stiffening plate (34) of the undeformed section is spaced 500mm apart from the first stiffening plate (26) of the adjacent deformed section, and the second stiffening plate (35) of the undeformed section is spaced 500mm apart from the second stiffening plate (27) of the adjacent deformed section.

8. The portal steel frame structure deformable I-beam reinforcement structure according to claim 1, characterized in that, The contour formed by the side surface where the first stiffening plate (26) of the deformable segment connects with the deformable segment (20) is the same as the deformation contour of the deformable segment (20) used to install the first stiffening plate (26).

9. The portal steel frame structure deformable I-beam reinforcement structure according to claim 1, characterized in that, The contour formed by the side surface where the second stiffening plate (27) of the deformable segment connects with the deformable segment (20) is the same as the deformation contour of the deformable segment (20) used to install the second stiffening plate (27).

10. A portal steel frame structure deformable I-beam reinforcement structure according to claim 4, characterized in that, The first and second reinforcement structures are made of carbon structural steel.

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