Kentilever girder with residual stress, its manufacturing method, and extended footbridge using it

Abstract

The present invention relates to a cantilever girder with introduced residual stress, a method for manufacturing the same, and an extended pedestrian bridge using the same. By applying prestress so that compressive and tensile stresses act on the upper and lower ends of a steel member, stress is applied in advance before the structure receives an actual load, thereby having the effect of offsetting tensile and compressive stresses caused by the load even when an external load is applied. The cantilever girder with introduced residual stress according to the present invention comprises: a steel member (10) having a wave (13) formed between an upper flange (11) and a lower flange (12); and an upper reinforcing plate (20) formed such that compressive stress acts on the upper end and tensile stress acts on the lower end of the steel member (10) after being welded while positioned on the upper flange (11) of the steel member (10) in a state where the center sags downward due to the application of a vertical load, and then the load is released. The invention is characterized by including a lower reinforcing plate (30) formed such that compressive stress acts on the upper part and tensile stress acts on the lower part of the steel member (10) after the upper reinforcing plate (20) is welded, the steel member (10) is in a state where it is placed on the upper part of the lower flange (12) after the upper reinforcing plate (20) is welded and the center is sagged downward due to the action of a separate vertical load, and then the load is released.

Description

Technology Field

[0001] The present invention relates to a cantilever girder with introduced residual stress, a method for manufacturing the same, and an extended pedestrian bridge using the same. More specifically, it relates to a cantilever girder with introduced residual stress, a method for manufacturing the same, and an extended pedestrian bridge using the same, wherein stress is applied in advance before the structure receives an actual load by applying prestress to the upper and lower ends of a steel member so that compressive and tensile stresses act on the structure, thereby offsetting tensile and compressive stresses caused by the load even when an external load is applied. Background Technology

[0003] Generally, columns are connected at predetermined intervals to steel beams that support slabs laterally, taking into account deflection due to self-weight. These columns installed at predetermined intervals reduce the variability of the design and aesthetics of buildings and civil engineering structures and are a factor in increasing construction costs.

[0004] Recently, active research has been conducted on prestress and preflex methods as ways to reduce the number of columns in buildings and civil engineering structures, and buildings and civil engineering structures applying these methods are emerging.

[0005] The above Prestress and Preflex methods offset the bending moment of a steel beam caused by its own weight by applying prestress with a bending moment in the opposite direction. The above prestress method is applied to civil engineering structures such as bridges.

[0006] In a steel beam to which the conventional prestressing method is applied, fixing members are installed at both lower ends of the H-beam, and both ends of a tension wire having a predetermined tensile force are fixed to the fixing members.

[0007] However, steel beams prestressed by tension wires installed at the bottom of the H-beam have a problem in that the width (h) of the steel beam—that is, the structural height—increases by the width of the tension wires and the fixing members. Therefore, applying prestress to steel beams leads to the problem of limiting the number of floors in buildings of a certain height due to the width of the steel beams.

[0008] Meanwhile, the conventional pre-flex method is applied to large-scale buildings, and prestress is applied to the steel beam by installing reinforced concrete for prestressing at the bottom of the H-beam. The reinforced concrete has a '∩'-shaped bending moment to offset the 'U'-shaped deflection of the H-beam.

[0009] However, the conventional preflex method increases the self-weight of the steel beam and causes problems such as increased construction costs and extended construction periods due to the fabrication of reinforced concrete. Furthermore, as time passes and the deflection of the H-beam becomes greater than the amount of prestress in the reinforced concrete, there is a problem in that cracks caused by shear failure occur from the bottom surface of the reinforced concrete. Prior art literature

[0011] Republic of Korea Registration No. 10-1103557 (Registration Date: January 2, 2012) Republic of Korea Registration No. 10-1692488 (Registration Date: December 28, 2016) The problem to be solved

[0012] In order to solve the aforementioned problems, the technical objective of the present invention is to present a cantilever girder with introduced residual stress, a method for manufacturing the same, and an extended pedestrian bridge using the same.

[0013] In addition, another technical objective of the present invention is to provide a cantilever girder with residual stress that can offset tensile and pressure stresses caused by the load even when an external load is applied, by applying prestress to the upper and lower ends of the steel member so that compressive and tensile stresses are applied in advance before the structure receives an actual load, and a method for manufacturing the same, and an extended pedestrian bridge using the same.

[0014] In addition, another technical objective of the present invention is to provide a cantilever girder with introduced residual stress by applying prestress so that compressive stress acts on the upper end and tensile stress acts on the lower end of the steel member, by sequentially placing upper and lower reinforcing plates on the upper and lower flanges of the steel member, then rigidly joining the upper and lower reinforcing plates by welding while the center of each plate sags downward due to a load, and then restoring the steel member to its original shape through load release.

[0015] In addition, another technical objective of the present invention is to provide a cantilever girder with introduced residual stress that allows the cantilever girder, steel joists, and composite floor slabs to be easily constructed without damage caused by drilling, a method for manufacturing the same, and an extended pedestrian bridge using the same.

[0016] In addition, another technical objective of the present invention is to provide a cantilever girder that is free from deformation such as warping or cracking caused by moisture and sunlight, has a semi-permanent lifespan, is lightweight, and has increased impact strength, as well as a method for manufacturing the same and an extended pedestrian bridge using the same.

[0017] The problems solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0019] As a means to solve the aforementioned technical problem, the method for manufacturing a cantilever girder with introduced residual stress according to the present invention comprises: a) placing an upper reinforcing plate (20) having the same length as the steel member (10) on the upper flange (11) of the steel member (10), and applying a vertical load on the upper reinforcing plate (20) so that the center of the upper reinforcing plate (20) sags downward together with the steel member (10), and welding both sides of the upper reinforcing plate (20) along the longitudinal direction of the steel member (10); b) releasing the load after welding so that compressive stress acts on the upper end of the steel member (10) and tensile stress acts on the lower end. c) after the steel member (10) with the upper reinforcing plate (20) welded thereon is flipped upside down, a lower reinforcing plate (30) is placed on the upper flange (12) of the steel member (10), and after the upper reinforcing plate (20) is prestressed, the lower reinforcing plate (30) is welded on both sides along the longitudinal direction of the steel member (10) while the center of the lower reinforcing plate (30) is sagged downward together with the steel member (10) by a separate load application; d) after the welding, the load is released so that compressive stress acts on the upper end of the steel member (10) and tensile stress acts on the lower end; and e) the upper reinforcing plate (20) and the lower reinforcing plate (30) are each used as a cantilever girder to form prestress on the steel member (10) through load application and release.As a means to solve the aforementioned technical problem, the cantilever girder with introduced residual stress according to the present invention comprises: a steel member (10) having a wave (13) formed between an upper flange (11) and a lower flange (12); and an upper reinforcing plate (20) formed such that compressive stress acts on the upper end and tensile stress acts on the lower end of the steel member (10) after welding while the center is sagging downward due to the application of a vertical load while the steel member (10) is positioned on the upper flange (11) of the steel member (10) and then the load is released. The present invention is characterized by including: a lower reinforcing plate (30) formed such that compressive stress acts on the upper part and tensile stress acts on the lower part of the steel member (10) after the upper reinforcing plate (20) is welded, the steel member (10) is in a state where it is placed on the upper part of the lower flange (12) after the upper reinforcing plate (20) is welded and the center is sagged downward due to the application of a separate vertical load after prestress is formed by the upper reinforcing plate (20). As a means to solve the aforementioned technical problem, the extension pedestrian bridge according to the present invention comprises, in an extension pedestrian bridge using a cantilever girder, a steel joist (220) arranged parallel to the upper part of the cantilever girder (100); and a composite material floor plate (240) arranged on the upper part of the steel joist (220). and a connecting device part (280) connecting the cantilever girder (100) and the steel joist (220); wherein the cantilever girder (100) is characterized by having prestress introduced by an upper reinforcing plate (20) and a lower reinforcing plate (30).

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[0023] The above-described extended pedestrian bridge comprises: a square tube-shaped steel joist (220) installed parallel to the upper part of the cantilever girder (100); a composite material floor plate (240) installed parallel to the upper part of the steel joist (220) in a vertical direction and having an anti-static and anti-slip layer (250) formed on its upper surface; and a square tube-shaped handrail foundation frame (210) installed at one end or both ends of the composite material floor plate (240) installed on the upper part of the cantilever girder (100). A girder joist coupling device (280) for fixing the steel joist (220) to the cantilever girder (100), comprising a girder joist coupling clip (260) installed on the upper surface of the steel joist (220), and a girder joist coupling spring (270) that inserts a horizontal joist section (271) into both wing sections (261) of the girder joist coupling clip (260) and fixes the hook section (272) of a circular spring (273) formed on both sides of the horizontal joist section (271) by fitting it to both corners of the cantilever girder (100); and after inserting into the steel joist (220), the insertion groove (241) of the composite floor plate (240) is fitted into the horizontal insertion part (234) formed outwardly on both upper sides, thereby fixing the composite floor plate (240) on the steel joist (220). It may be configured to include a deck fixing device (230) made of metal material of the shape. Effects of the invention

[0025] According to the present invention, upper and lower reinforcing plates are sequentially placed on the upper and lower flanges of a steel member, and then, while the center of each plate is sagging downward due to a load, the upper and lower reinforcing plates are rigidly joined by welding. Afterward, the steel member is restored to its original shape through load release, thereby applying prestress such that compressive stress acts on the upper part and tensile stress acts on the lower part of the steel member. This allows stress to be applied in advance before the structure receives an actual load, so that even if an external load is applied, the tensile and compressive stresses caused by the load can be offset.

[0026] In addition, it prevents damage such as cracking caused by shear failure at the bottom of reinforced concrete, and can accelerate construction by reducing the time required for tensioning tension members, pouring, and curing reinforced concrete. It also offers excellent constructability, and since all materials are manufactured separately and uniformly, it ensures superior quality and stability.

[0027] In addition, since the self-weight is reduced by using steel, long-span beams can be realized, which not only allows for the design of high-rise buildings but also minimizes the number of required columns to secure sufficient variable space, thereby enhancing the aesthetics and ensuring design variability of civil structures and buildings such as long-span bridges, low-height bridges, theaters, department stores, parking lots, and gymnasiums.

[0028] In addition, steel beams with prestressed steel beams applied within the width of the beam can reduce the volume of upper and lower structures by minimizing the number of required columns, which has the advantage of reducing construction costs and shortening the construction period for civil engineering structures and buildings.

[0029] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0031] FIGS. 1 to 8 are a side view (a), a cross-sectional view (b), and a stress distribution diagram (c) illustrating a method for manufacturing a cantilever girder with introduced residual stress according to an embodiment of the present invention. FIGS. 9 and 10 are a configuration diagram and a cross-sectional view of an extended pedestrian bridge (200) without a handrail, including a cantilever girder (100) that introduces residual stress according to the present invention. FIG. 11 is a diagram showing the configuration of a hollow composite floor plate (240) and a steel joist (220). FIGS. 12 to 14 are configuration diagrams of a deck fixing device (230). FIGS. 15 to 17 are diagrams of the structure of a hollow composite material bottom plate (240). FIGS. 18 to 22 are configuration diagrams of a girder joist connection clip (260) and a joist connection spring (270). FIGS. 23 and 24 are cross-sectional views showing an example of an extended pedestrian bridge (200) without a handrail, including a cantilever girder (100) that introduces residual stress according to the present invention. Specific details for implementing the invention

[0032] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the invention in the drawings, parts unrelated to the description have been omitted, and similar parts throughout the entire description of the invention are described using similar reference numerals.

[0033] Meanwhile, the terms used in this invention have been selected to be as widely used as possible, taking into account their functions within the invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention.

[0034] Furthermore, when a part of the specification is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude the following component but may include additional components.

[0035] First, a cantilever is a structure that is fixed on one side and floating on the other, and a girder is a main beam that supports the load.

[0036] The above-mentioned cantilever is a beam in which one end is fixed and the other end is unsupported. Although it has a light appearance, it is prone to deformation as it receives four times the bending moment compared to an ordinary beam of the same length, so caution is required in strength design. A cantilever is also called a cantilever beam and is widely used in bridges, slopes, retaining walls, concrete walls, pedestrian bridges, etc.

[0037] Hereinafter, specific technical details to be implemented in the present invention will be described in detail with reference to the attached drawings.

[0039] Method for manufacturing a cantilever girder

[0040] FIGS. 1 to 8 are a side view (a), a cross-sectional view (b), and a stress distribution diagram (c) illustrating a method for manufacturing a cantilever girder with introduced residual stress according to an embodiment of the present invention.

[0041] First, referring to FIG. 1, an upper reinforcing plate (20) is placed on the upper flange (11) of a steel member (10).

[0042] The above steel member (10) may be composed of a steel I-beam in which a wave (13) is formed vertically between the upper flange (11) and the lower flange (12).

[0043] The above steel member (10) is not subjected to stress initially. The above steel member (10) can generally be constructed using a steel I-beam or a steel H-beam. Additionally, in the present invention, a pre-bent preflex beam may be used as the above steel member (10).

[0044] The upper reinforcing plate (20) above may be made of steel plate, but steel H-beams or steel I-beams may be used to further increase rigidity. In addition, any shape of built-up beam or U-channel manufactured on-site may be used.

[0045] The upper reinforcing plate (20) may be composed of steel with a higher yield stress than the steel profile (10). For example, it may be formed of POSTEN steel (POSCO product), TMCP type high-strength steel plate (POSCO product), a higher grade of the same steel with a higher yield stress, or other steel grades with a higher yield stress.

[0046] The upper reinforcing plate (20) can be formed to be equal in length to both ends of the steel member (10).

[0047] Referring to FIG. 2, when a vertical load (P) is applied to the upper reinforcing plate (20) positioned on the upper flange (11) of the steel member (10), the center of the steel member (10) and the upper reinforcing plate (20) sag downward and deform.

[0048] With the above applied load (P) applied vertically downward, the upper reinforcing plate (20) is fixed to the upper part of the steel member (10) by welding. At this time, the welding is performed to rigidly join both ends of the upper reinforcing plate (20) along the longitudinal direction of the steel member (10). At this time, the welding is performed at the point where the load is applied. In FIG. 2, reference numeral 21 indicates a welded part.

[0049] Referring to the stress distribution diagram (c) in FIG. 2 when the above applied load is applied vertically downward, compressive stress acts on the upper part and tensile stress occurs on the lower part. This indicates the load application stage, and the load application may be achieved by applying a concentrated load from the upper or lower part, or by a distributed load. Compressive stress acts on the upper part of the steel member (10) and tensile stress acts on the lower part.

[0050] Next, referring to FIG. 3, with the load (P) applied vertically downward, both sides of the upper reinforcing plate (20) are rigidly joined by welding along the longitudinal direction of the steel member (10), and then the load is removed. At this time, the welding is performed at the point where the load is applied. When the load is released, the steel member (10) and the upper reinforcing plate (20) are restored to their original state by the restoring force in the part where the center has sagged downward due to the load.

[0051] However, even if the shape is restored to its original state by the release of the load, compressive stress acts on the upper part of the steel member (10) and the upper reinforcing plate (20), and tensile stress acts on the lower part. That is, when the moment generated during load application is released, compressive stress and tensile stress resulting from the release of the load are generated and exist at the upper and lower parts, respectively (refer to the stress distribution diagram (c) of FIG. 3).

[0052] Next, referring to FIG. 4, after the steel member (10) with the upper reinforcing plate (20) welded thereto is flipped upside down, a lower reinforcing plate (30) is placed on the upper flange (12) of the steel member (10).

[0053] The lower reinforcing plate (30) may be made of steel plate, just like the upper reinforcing plate (20), but steel H-beams or steel I-beams may be used to further increase rigidity. Additionally, any shape of built-up beam or U-channel manufactured on-site may be used.

[0054] The lower reinforcing plate (30) may be composed of steel with a higher yield stress than the steel profile (10). For example, it may be formed of POSTEN steel (POSCO product), TMCP type high-strength steel plate (POSCO product), a higher grade of the same steel with a higher yield stress, or other steel grades with a higher yield stress.

[0055] The lower reinforcing plate (30) can be formed to be equal in length to both ends of the steel member (10).

[0056] Referring to FIG. 5, when a vertical load (P) is applied to the upper part of the lower reinforcing plate (30) positioned on the lower flange (12) of the steel member (10), the center of the steel member (10) and the lower reinforcing plate (30) sag downward and deform. At this time, while the applied load is applied vertically downward, both sides of the lower reinforcing plate (30) are rigidly joined by welding along the longitudinal direction of the steel member (10), and then the load is removed. At this time, the welding is performed at the point where the load is applied. When the load is released, the part of the steel member (10) and the lower reinforcing plate (30) that sagged downward due to the load is restored to its original state by the restoring force.

[0057] However, even if the shape is restored to its original state by the release of the load, compressive stress acts on the upper part of the steel member (10) and the lower reinforcing plate (30), and tensile stress acts on the lower part. That is, when the moment generated during load application is released, compressive stress and tensile stress resulting from the release of the load are generated and exist at the upper and lower parts, respectively (refer to the stress distribution diagram (c) of FIG. 4).

[0058] Referring to the stress distribution diagram (c) in FIG. 5 when the above applied load is applied vertically downward, compressive stress acts on the upper part and tensile stress occurs on the lower part. This indicates the load application stage, and the load application may be achieved by applying a concentrated load from the upper or lower part, or by a distributed load. Compressive stress acts on the upper part of the steel member (10) and tensile stress acts on the lower part.

[0059] With the above applied load (P) applied vertically downward, the lower reinforcing plate (30) is fixed to the upper part of the steel member (10) by welding. At this time, the welding fixes both ends of the lower reinforcing plate (30) along the longitudinal direction of the steel member (10). In FIG. 5, reference numeral 31 indicates a welded part.

[0060] Next, referring to FIG. 6, the lower reinforcing plate (30) is fixed by welding to the upper part of the steel member (10) while the load (P) is applied vertically downward, and then the load is removed. When the load is released, the steel member (10) and the lower reinforcing plate (30) are restored to their original state by the restoring force in the part where the center has sagged downward due to the load.

[0061] Even if the shape is restored to its original state by the release of the load, compressive stress acts on the upper part of the steel member (10) and the lower reinforcing plate (30), and tensile stress acts on the lower part. That is, when the moment generated during load application is released, compressive stress and tensile stress resulting from the load release occur and exist at the upper and lower parts, respectively.

[0062] However, the compressive stress acting on the upper part of the steel member (10) is offset by the tensile stress remaining during welding of the upper reinforcing plate (20) and becomes '0'. In other words, no stress is applied. Also, the tensile stress acting on the lower part of the steel member (10) is offset by the compressive stress remaining during welding of the upper reinforcing plate (20) and becomes '0'. In other words, no stress is applied.

[0063] Referring to the stress distribution diagram (c) of FIG. 6, when the load is removed after welding the lower reinforcing plate (30), the steel member (10) and the lower reinforcing plate (30) are restored to their original state by the restoring force in the part where the center has sagged downward due to the load, but compressive stress acts on the upper part of the steel member (10) and the lower reinforcing plate (30) and tensile stress acts on the lower part. That is, when the moment generated during load application is released, compressive stress and tensile stress resulting from the release of the load are generated and exist at the upper and lower parts, respectively.

[0064] By applying prestress by rigidly joining the upper reinforcing plate (20) and the lower reinforcing plate (30) while stress is applied to the upper and lower parts of the above steel member (10), stress (compressive force) is applied in advance before the structure receives an actual load, so that tensile stress and pressure stress caused by the load can be simultaneously offset even when an external load is applied. As a result, cracks can be reduced, sagging can be reduced, and a longer span (distance) can be secured.

[0065] Finally, the upper and lower reinforcing plates (20, 30) are rigidly joined to the upper and lower flanges (11, 12) by welding, and a steel member (10) with applied prestress is used as a cantilever girder (100) of an extended pedestrian bridge (200). At this time, the cantilever girder (100) of the extended pedestrian bridge (200) can be used by cutting the steel member (10).

[0066] The cantilever girder (100) with residual stress introduced in the present invention can be used in expanded pedestrian bridges such as slope expanded pedestrian bridges, bridge expanded pedestrian bridges, and retaining wall expanded pedestrian bridges.

[0068] Application example of a cantilever girder (100)

[0069] FIGS. 9 and 10 are a configuration diagram and a cross-sectional view of an extended pedestrian bridge (200) without a handrail, including a cantilever girder (100) that incorporates residual stress according to the present invention. FIG. 11 is a configuration diagram of a hollow composite floor plate (240) and a steel joist (220), FIGS. 12 to 14 are configuration diagrams of a deck fixing device (230), FIGS. 15 to 17 are configuration diagrams of a hollow composite floor plate (240), and FIGS. 18 to 22 are configuration diagrams of a girder joist connecting clip (260) and a joist connecting spring (270).

[0070] As shown in FIGS. 9 to 22, the extended pedestrian bridge (200) without a handrail, including the cantilever girder (100) with residual stress introduced according to the present invention, is composed of a cantilever girder (100), a handrail foundation frame (210), a steel joist (220), a deck fixing device (230), a composite material floor plate (240), and a girder joist coupling device part (280).

[0071] The above-mentioned extended pedestrian bridge (200) is an example in which cantilever girders (100) are installed horizontally at regular intervals on a concrete wall.

[0072] The cantilever girder (100) above may be constructed using the cantilever girder (100) described in FIGS. 1 to 8.

[0073] The cantilever girder (100) is fixed to a concrete wall by attaching a base plate (111) to the concrete wall and driving or fastening a chemical anchor (120). At this time, an elastic rubber pad (not shown) may be optionally installed between the base plate (111) of the cantilever girder (100) and the concrete wall.

[0074] Here, the elastic rubber pad prevents the gap that occurs between the base plate (111) of the cantilever girder (100) and the concrete wall, and serves to mitigate vibrations transmitted through the cantilever girder (100).

[0075] The above elastic rubber pad is not a mandatory component that must be installed, and may be installed optionally as needed.

[0076] The above-mentioned extended pedestrian bridge (200) is formed by horizontally installing the above-mentioned cantilever girder (100) at predetermined intervals on a concrete wall, and then installing the above-mentioned steel joist (220) on the top of the above-mentioned cantilever girder (100).

[0077] The above steel joists (220) are installed parallel to each other at predetermined intervals in a vertical direction on the top of the bracket and may be composed of square tubes.

[0078] The above steel joist (220) may have a joist extension connecting part (221) formed at one end separated to be fitted together in the middle. The joist extension connecting part (221) is configured to connect the two separated steel joists (220) to each other by fitting together, thereby enabling extension and length adjustment in the longitudinal direction.

[0079] The above steel joist (220) can be fixedly installed on the upper part of the cantilever girder (100) by the girder joist coupling device part (280).

[0080] Here, the girder joist coupling device (280) is composed of a girder joist coupling clip (260) and a girder joist coupling spring (270).

[0081] The above-mentioned girder joist connecting clip (260) is installed on the upper surface of the steel joist (220) and forms wing portions (261) on both sides with a downward slope. The above-mentioned girder joist connecting spring (270) has circular springs (273) formed on both sides of the horizontal joist portion (271), and a hook portion (272) in the shape of '┗' and / or '┛' is formed at the end of the circular spring (273).

[0082] The above girder joist coupling device (280) can secure the steel joist (220) to the upper part of the cantilever girder (100) by placing the girder joist coupling clip (260) on the upper surface of the steel joist (220), inserting the horizontal joist portion (271) of the girder joist coupling spring (270) into the two wing portions (261) of the girder joist coupling clip (260), and fitting the hook portion (272) formed on the two circular springs (273) to the two corners of the cantilever girder (100).

[0083] On the upper part of the steel joist (220), the composite material floor plate (240) is installed parallel to the steel joist (220) in a vertical direction.

[0084] The composite material floor plate (240) may be formed from 60 to 75 weight percent glass fiber and 25 to 40 weight percent resin mixture. At this time, the resin mixture may consist of 65 to 75 weight percent resin and 25 to 35 weight percent aluminum hydroxide. The composite material floor plate (240) has a rectangular cross-section, a space formed inside by a vertical partition, insertion grooves formed in the longitudinal direction on both sides, and an anti-static and anti-slip layer (250) formed on the upper surface.

[0085] The above anti-static and anti-slip layer (250) may be formed on the upper surface of the composite material floor plate (240) with a thickness of 0.1 to 1.0 mm and may be formed from a mixture of 60 to 75 weight percent silica sand film and 25 to 40 weight percent resin mixture. Here, the resin mixture is composed of 65 to 75 weight percent resin and 25 to 35 weight percent aluminum hydroxide, and the resin may be composed of polyvinyl chloride, polyethylene, and polypropylene.

[0086] The above electrostatic and anti-slip layer (250) may have an upper surface that is rough, bumpy, or has protrusions formed integrally to prevent slipping.

[0087] In addition, as another embodiment, the electrostatic and anti-slip layer (250) may be formed on the upper surface of the pre-treated layer after performing a pre-treatment operation on the upper surface of the composite material floor plate (240).

[0088] In addition, as another embodiment, the above-mentioned anti-static and anti-slip layer (250) may be formed by further mixing 20 to 50 parts by weight of glass fiber or carbon fiber with 100 parts by weight of a mixture of 60 to 75 parts by weight of silica sand film and 25 to 40 parts by weight of resin mixture. At this time, the resin mixture may consist of 65 to 75 parts by weight of synthetic resin and 25 to 35 parts by weight of aluminum hydroxide, and the synthetic resin may be composed of polyvinyl chloride, polyethylene, and polypropylene.

[0089] In addition, as another embodiment, the above-mentioned anti-static and anti-slip layer (250) may be formed by mixing 10 to 30 parts by weight of loess with 100 parts by weight of a mixture of 60 to 75 parts by weight of silica film and 25 to 40 parts by weight of resin mixture.

[0090] The composition and manufacturing method of the above composite material floor plate (240) will be described in more detail in FIGS. 15 to 17, which will be described later.

[0091] The composite floor plate (240) is fixedly installed on the steel joist (220) using the deck fixing device (230).

[0092] The above deck fixing device (230) is The composite material floor plate (240) is fixed by inserting a horizontal insertion part (234) into an insertion groove (241) of the composite material floor plate (240) which has a shape and is installed by being inserted into the steel joist (220) and then placed on the upper part of the steel joist (220) (see FIGS. 11 to 14).

[0093] The handrail foundation frame (210) may be installed at one end (see FIG. 9, FIG. 10) or both ends (see FIG. 26 to FIG. 28) of the upper part of the cantilever girder (100).

[0094] The above handrail foundation frame (210) is formed in the shape of a square tube and has a space formed inside. To prevent lifting caused by expansion and contraction of the composite material floor plate (240), the above handrail foundation frame (210) may be configured to be positioned with a predetermined gap between the composite material floor plate (240) and the above handrail foundation frame (210) to ensure clearance.

[0095] The above railing foundation frame (210) may be formed as a square tube. In this case, the above railing foundation frame (210) may be made of a metal material. However, it may also be formed of the same glass fiber reinforced composite material as the above composite material floor plate (240).

[0096] The above-mentioned extended pedestrian bridge (200) can be constructed by installing a cantilever girder (100) on a concrete structure (see 300 in FIG. 23) or a concrete wall, and then installing a steel joist (220) and a composite floor plate (240) on top of it.

[0097] In addition, as another example, the above-mentioned extended pedestrian bridge (200) may be constructed by installing a cantilever girder (100) on the outside of an existing bridge and retaining wall, and then installing a steel joist (220) and a composite floor plate (240) on top of it.

[0098] In addition, as another example of the above-mentioned extended pedestrian bridge, an H-pipe and an earth anchor are drilled and inserted into the outer side of the existing road, and a concrete beam is formed on the upper side, and the extended pedestrian and bicycle path can be installed using the above-mentioned composite floor plate (240).

[0099] The above cantilever girder (100) can be installed at predetermined intervals on the outer side of existing bridges and retaining walls or on the outer side of existing roads.

[0100] A composite material floor plate (240) may be installed on the upper part of the steel joist (220) in a direction parallel to the steel joist (220) in a vertical direction. At this time, the composite material floor plate (240) is fixedly installed on the steel joist (220) using the deck fixing device (230).

[0101] The above steel joists (220) are installed at regular intervals in a vertical direction on the top of the bracket and can be composed of square tubes in the shape of a '□'.

[0102] The above deck fixing device (230) is The composite material floor plate (240) is fixed by inserting a horizontal insertion part (134) into an insertion groove (141) of the composite material floor plate (240) which has a shape and is installed by being inserted into the steel joist (220) and then placed on the upper part of the steel joist (220) (see FIG. 12 and FIG. 13).

[0103] As shown in FIG. 14, the above deck fixing device (230) is composed of a rectangular lower surface (231), rectangular side surfaces (232) formed vertically on both sides of the lower surface (231), a neck portion (233) formed on the upper part of the side surfaces (232) with a width narrower than that of the side surfaces (232), and a horizontal insertion portion (234) bent horizontally outward at the top of the neck portion (233).

[0104] An embossing (235) may be formed protrudingly on the upper surface of the lower surface (231), and an embossing (235) may also be formed protrudingly on the inner side of the side surface (232). Additionally, the upper corners of both sides of the side surface (232) may be finished diagonally or in a curved shape.

[0105] The material of the above deck fixing device (230) may be composed of galvanized steel, and the sharp edges on both upper sides may be finished to prevent accidents, and both sides (232) may be formed by bending at 90 degrees. In addition, the above deck fixing device (230) may be protected by galvanizing and may be coated with an anti-rust agent.

[0106] The above deck fixing device (230) is installed by inserting it from bottom to top of the steel joist (220), and the composite floor plate (240) is fixed by inserting a horizontal insertion part (234) into the insertion groove (241) of the composite floor plate (240) positioned on top of the steel joist (220).

[0107] The embossing (235) formed on the inner side of the deck fixing device (230) serves to securely fix the deck fixing device (230) to the steel wire (220) without it coming loose. That is, the embossing (235) prevents a gap from forming between the steel wire (220) and the deck fixing device (230), thereby increasing the adhesion and preventing movement.

[0108] When the deck fixing device (230) is installed on the steel wire (220), the neck portion (233) and the horizontal insertion portion (234) of the deck fixing device (230) protrude over the steel wire (220), and by inserting the horizontal insertion portion (234) of the deck fixing device (230) into the insertion groove (241) formed on the side of the composite floor plate (240), the steel wire (220) and the composite floor plate (240) can be connected and firmly fixed (see FIG. 12 and FIG. 13).

[0109] Meanwhile, the steel joist (220) is separated so that the middle part is connected by a snap-fit ​​connection, and a joist extension connection part (221) is configured on one side of the separation to be snap-fit ​​connected with the other steel joist. Accordingly, the steel joist (220) can be extended in the longitudinal direction by the joist extension connection part (221), and the length of the steel joist (220) can be adjusted.

[0110] The deck fixing device (230) has a horizontal insertion part (234) formed on the same horizontal line as the insertion groove (241) of the composite material floor plate (240). Additionally, depending on the case, the area of ​​the horizontal insertion part (234) is increased to widen the contact area with the insertion groove (241) of the composite material floor plate (240), thereby allowing the steel joist (220) and the composite material floor plate (240) to be fixed more securely.

[0111] The above deck fixing device (230) can prevent accidents in which a worker is injured by sharp corners during deck construction by finishing both corners of the side (232) diagonally or curvedly.

[0112] As shown in FIGS. 15 to 17, the above composite material bottom plate (240) has a rectangular cross-section, and a space (242) is formed inside by a vertical partition (243), and insertion grooves (241) may be formed inwardly along the longitudinal direction on both sides. At this time, the insertion grooves (241) formed on both sides may be formed in a '⊃' or '⊂' shape.

[0113] The composite material floor plate (240) may be formed from 60 to 75 weight percent glass fiber and 25 to 40 weight percent resin mixture. Preferably, the composite material floor plate (240) may be formed from 68 weight percent glass fiber and 32 weight percent resin mixture.

[0114] Here, the glass fibers can be formed using alkali-free sand or medium-alkali sand. Alkali-free sand is used when strength is required and corrosion resistance is high, whereas medium-alkali sand has low strength and lower corrosion resistance than alkali-free sand. Therefore, the composite floor plate (240) of the present invention is formed using alkali-free sand as a glass fiber material.

[0115] The resin mixture may consist of 65 to 75 weight percent resin and 25 to 35 weight percent aluminum hydroxide. Preferably, the resin mixture may be formed with 70 weight percent resin and 30 weight percent aluminum hydroxide.

[0116] The types of resins mentioned above include MP-5 (phenolaldehyde type) resin, VERF-25 (ethylene type) resin, VEFR-10 (ethylene type) resin, IFR-25 (benzene type) resin, IFGR-30 (benzene food grade) resin, OFR-25 (phthalene type) resin, OCR (phthalene type) resin, etc., and can be composed by selectively using any of these.

[0117] Here, the flame retardancy of the resin is such that, in the case of the MP-5 (phenolaldehyde type) resin, the oxygen level is up to about 80; in the case of the VERF-25 (ethylene type) resin, the oxygen level is 28 or higher; in the case of the VEFR-10 (ethylene type) resin, the oxygen level is 35 or higher; in the case of the IFR-25 (benzene type) resin, the oxygen level is 28 or higher; in the case of the IFGR-30 (benzene food grade) resin, the oxygen level is 26 or higher; in the case of the OFR-25 (phthalene type) resin, the oxygen level is 28 or higher; and in the case of the OCR (phthalene type) resin, the oxygen level is 28 or lower.

[0118] Among these, the above IFR-25 (sodium benzene type) resin has good non-VEFR type economy and acid resistance, and excellent properties against salt and solvents, so the composite material bottom plate (140) of the present invention is formed using the above IFR-25 (sodium benzene type) resin.

[0119] The above aluminum hydroxide has superior properties compared to other resin mixture fillers (e.g., calcium carbonate, etc.), such as flame retardancy, smoke suppression, corrosion prevention, anti-aging, and insulation performance.

[0120] Compared to conventional wooden decks or wood composite decks, the above composite material floor plate (240) has lightweight, high strength, and high durability properties, and has a significantly lower moisture absorption rate, so there is no deformation of the material and performance such as durability is greatly improved.

[0121] The above composite material floor plate (240) may be configured by forming an anti-static and anti-slip layer (250) on its upper surface. The anti-static and anti-slip layer (150) may be formed with a thickness of 0.1 to 1.0 mm on the upper surface of the glass fiber reinforced floor plate member.

[0122] The above anti-static and anti-slip layer (250) can be formed by mixing 60 to 75 weight percent of a silica sand film and 25 to 40 weight percent of a resin mixture. Here, the resin mixture consists of 65 to 75 weight percent of resin and 25 to 35 weight percent of aluminum hydroxide, and the resin includes polyvinyl chloride, polyethylene, and polypropylene.

[0123] Since the above anti-static and anti-slip layer (250) is formed from a silica sand film and a resin mixture, it can prevent static electricity generated when a pedestrian holds the railing with their hand.

[0124] For reference, the above silica sand refers to quartz grain sand rich in silicon dioxide (SiO₂), a silicic acid component.

[0125] The above silica sand refers to sand whose main component is silicon dioxide (SiO2). It is broadly classified into natural silica sand and artificial silica sand, and the present invention includes both natural silica sand and artificial silica sand.

[0126] Natural silica sand is formed by the weathering of rocks containing large amounts of quartz, such as granites and granitic gneiss. It is divided into two forms depending on the weathering, erosion, and deposition processes: one is residual silica sand or acid silica, which is formed when the parent rock weathers and only the light clay components are washed away by water, leaving only the quartz grains in place; the other is sedimentary silica, which is formed when quartz grains are carried along by river water along with clay and other materials, and then separated by differences in specific gravity, depositing only the quartz at specific locations along the riverbank. Artificial silica sand (or silver sand) refers to silica sand produced by selectively crushing only the quartz contained primarily in pegmatites to create a sand-like particle size.

[0127] Quartz, which constitutes silica sand, is represented by the chemical formula SiO₂ and consists of silicon (Si) (46.7%) and oxygen (O) (53.3%), which are the most abundant elements in the Earth's crust. Its color varies depending on the type and content of impurities, appearing in white, yellow, purple, and black. Its streak is colorless, its hardness is 7, its specific gravity is approximately 2.65, and its melting point is 1,713 degrees Celsius. It possesses translucency, refractory properties, and high hardness; it is used as an oxidizing agent during deoxidation and desulfurization, and it exhibits semiconductive electrical properties and is easy to alloy.

[0128] Additionally, the anti-static and anti-slip layer (250) may have a rough or uneven surface or have protrusions formed integrally to prevent slipping. At this time, the anti-slip protrusions (251) may be formed with the same height and shape, or may be formed irregularly with different shapes.

[0129] Meanwhile, the above-mentioned anti-static and anti-slip layer (250) can be formed by mixing 20 to 50 parts by weight of glass fiber or carbon fiber with 100 parts by weight of a mixture of silica film and resin mixture.

[0130] The above glass fiber is produced by melting glass in a platinum furnace and dropping it through small holes to form long fibers; due to its excellent heat resistance, durability, sound absorption, and electrical insulation properties, it is used as a thermal insulation material, air filter, electrical insulator, and sound absorber.

[0131] The glass fibers in the present invention may be formed using alkali-free sand or medium-alkali sand. The alkali-free sand is used when strength is required and corrosion resistance is high, while the medium-alkali sand has low strength and lower corrosion resistance than the alkali-free sand. Accordingly, the composite floor plate (240) of the present invention is formed using the alkali-free sand as a glass fiber material.

[0132] The carbon fiber mentioned above is a fiber produced by heating and carbonizing organic fibers in an inert gas atmosphere. Raw materials used include cellulose, acrylic fiber, vinylon, and pitch; however, changes in molecular arrangement and crystal structure occur depending on the raw material or the processing temperature. Generally, it has a structure in which hexagonal carbon rings form a layered lattice; it has a metallic luster and appears black or gray. It has a strength of 10–20 g / d and a specific gravity of 1.5–2.1. It possesses excellent heat resistance and impact resistance, is resistant to chemicals, and has high resistance to pests. Since molecules such as oxygen, hydrogen, and nitrogen escape during the heating process, causing a reduction in weight, it is lighter than metal (aluminum), while having superior elasticity and strength compared to metal (iron).

[0133] The above resin mixture is composed of 65 to 75 weight percent synthetic resin and 25 to 35 weight percent aluminum hydroxide, and the above synthetic resin may be composed of polyvinyl chloride, polyethylene, and polypropylene.

[0134] In addition, the above synthetic resin can be formed using IFR-25 (non-benzene type) resin. The above IFR-25 (non-benzene type) resin has an oxygen level of 28 or higher, excellent flame retardancy, good economic efficiency and acid resistance, and excellent resistance to salt and solvents (see FIG. 8).

[0135] The above aluminum hydroxide is an aluminum hydroxide and is an amphoteric hydroxide. It gels when in contact with water for a long time and is used as an adsorbent, ion exchanger, fixative for chromatography, antacid, etc.

[0136] The chemical formula of the above aluminum hydroxide is Al(OH)3, and its specific gravity is 2.423. It has superior functions compared to other resin mixture fillers (e.g., calcium carbonate, etc.), such as flame retardancy, smoke suppression, corrosion prevention, anti-aging, and insulation performance.

[0137] In addition, the above-mentioned anti-static and anti-slip layer (250) can be formed by mixing 10 to 30 parts by weight of loess with 100 parts by weight of a mixture of silica film and resin mixture.

[0138] The aforementioned loess is a natural soil composed of silica and earth containing hydrated and anhydrous iron oxides. Loess is a pale yellow sediment consisting mainly of silt-sized particles loosely cemented by calcium carbonate; it is generally homogeneous with undeveloped bedding and has a high porosity. The particle size is 0.02–0.05 mm, containing coarse and medium-sized dust. The moisture content within the loess is low at 10–15% and increases as the porosity decreases. The porosity of sandy loess is approximately 60%, and its density is 1.5 g / cm³. 3 Its specific gravity is an average of 2.7. The mineral composition of loess contains 60–70% quartz, with the content varying from a minimum of 40% to a maximum of 80%. Feldspar and mica make up 10–20%, and carbonate minerals make up 5–35%. If one uses the above loess for mud, compresses, or forest bathing for several days, the protease enzymes present within it have the effect of detoxifying festering wounds or toxins in the body.

[0139] An embodiment of the present invention forms an anti-static and anti-slip layer (250) on the upper surface of the composite material floor plate (240) using a silica sand film and a resin mixture, and forms a rough, uneven, or protruding (251) on the surface of the anti-static and anti-slip layer (250) so as to safely protect pedestrians from static electricity generation and slipping.

[0140] In addition, the composite material floor plate (240) of the present invention has a superior moisture absorption rate compared to conventional wooden decks or wood composite decks, so there is no deformation of the member and performance such as durability can be greatly improved. In addition, by applying a silica sand coating to the composite material floor plate (240), slip resistance in all directions can be secured, thereby improving walking stability. Furthermore, since it is composed of a glass fiber reinforced composite material, it can be used semi-permanently, and because the deck replacement cycle can be extended by more than 5 to 10 times compared to conventional wooden decks or wood composite decks, maintenance costs can be greatly reduced.

[0141] Finally, FIGS. 23 and 24 are cross-sectional views showing an example of an extended pedestrian bridge (200) without a handrail, including a cantilever girder (100) that introduces residual stress of the present invention.

[0142] An extended pedestrian bridge (200) without a handrail, including a cantilever girder (100) with residual stress introduced according to the present invention, is configured to include a cantilever girder (100), a handrail foundation frame (210), a steel joist (220), a deck fixing device (230), and a composite floor plate (240), as shown in FIGS. 23 and 24.

[0143] The extended pedestrian bridge (200) of FIGS. 23 and 24 shows an example in which cantilever girders (100) are installed horizontally at regular intervals on the side walls of a concrete structure (300).

[0144] The cantilever girder (100) of the extended pedestrian bridge (200) of Fig. 23 is fixed by attaching a base plate (110) to the wall of the concrete structure (300) and driving or fastening a chemical anchor (120).

[0145] The cantilever girder (100) of the extended pedestrian bridge (200) of FIG. 24 is fixed by attaching a base plate (110) to the wall of the concrete structure (300) and driving or fastening a chemical anchor (120). In addition, an upper reinforcing plate (20) rigidly connected by applying prestress to the upper flange (101) of the cantilever girder (100) is placed on the upper part of the concrete structure (300), and is fixed by driving or fastening a chemical anchor (120) vertically.

[0146] In FIGS. 23 and 24, an elastic rubber pad (not shown) may be optionally installed between the base plate (110) of the cantilever girder (100) and the wall of the concrete structure (300).

[0147] As described above, the cantilever girder with introduced residual stress according to the present invention, the method of manufacturing the same, and the extended pedestrian bridge using the same can solve technical problems by applying prestress to the upper and lower ends of the steel member so that compressive and tensile stresses are applied, thereby applying stress in advance before the structure receives an actual load, and thus offsetting the tensile and compressive stresses caused by the load even when an external load is applied.

[0148] The preferred embodiments of the present invention described above are disclosed to solve technical problems, and a person with ordinary knowledge in the technical field to which the present invention belongs (a person skilled in the art) may make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications and changes should be considered to fall within the scope of the following claims. Industrial applicability

[0150] The cantilever girder with introduced residual stress according to the present invention and the method of manufacturing the same can be used as a cantilever girder, bracket, steel crossbeam, etc., for expanded pedestrian bridges and bridges. Explanation of the symbols

[0152] 10 : Steel profile 11 : Upper flange 12 : Lower flange 13 : Wave 20 : Upper reinforcement plate 21 : Welded part 30 : Lower reinforcement plate 31 : Welded part 100 : Cantilever girder 101 : Upper flange 102 : Lower flange 103 : Wave 110, 111 : Base plate 120 : Chemical anchor 200 : Extended pedestrian bridge 210 : Handrail foundation frame 211 : Bolt 220 : Steel joist (square tube) 221: Joist expansion joint 230: Deck fixing device 231 : If 232 : Side 233 : Neck section 234 : Horizontal insert section 235 : Embossing 240 : Composite flooring 241 : 'ㄷ'-shaped insertion groove 242 : Space part 243 : Partition 250 : Anti-static and anti-slip layer 251: Anti-slip protrusion 260: Clip for connecting girder joists 261: Wing section 270: Spring for connecting girder joists 271: Horizontal joist section 272: Hanging section 273: Round spring 280: Girder joist connecting device 300 : Concrete structure

Claims

Claim 1 A method for manufacturing a cantilever girder with introduced residual stress comprises: a) placing an upper reinforcing plate (20) having the same length as the steel member (10) on the upper flange (11) of the steel member (10), and applying a vertical load on the upper reinforcing plate (20) so that the center of the upper reinforcing plate (20) sags downward together with the steel member (10), and welding both sides of the upper reinforcing plate (20) along the longitudinal direction of the steel member (10); b) releasing the load after welding so that compressive stress acts on the upper end of the steel member (10) and tensile stress acts on the lower end; c) flipping the steel member (10) with the upper reinforcing plate (20) welded thereon upside down, placing a lower reinforcing plate (30) on the lower flange (12) of the steel member (10), and the lower reinforcing plate (30) is subjected to a separate load application after the prestress is formed of the upper reinforcing plate (20). A method for manufacturing a cantilever girder characterized by comprising: a step of welding both sides of a lower reinforcing plate (30) along the longitudinal direction of the steel member (10) while the center is sagging downward together with the steel member (10); a step of releasing the load after welding so that compressive stress acts on the upper part of the steel member (10) and tensile stress acts on the lower part; and a step of using the steel member (10), in which prestress is formed through the application and release of loads by the upper reinforcing plate (20) and the lower reinforcing plate (30), respectively, as a cantilever girder. Claim 2 delete Claim 3 In a cantilever girder with introduced residual stress, a steel member (10) having a wave (13) formed between an upper flange (11) and a lower flange (12); an upper reinforcing plate (20) formed such that compressive stress acts on the upper end and tensile stress acts on the lower end of the steel member (10) after being welded while positioned on the upper flange (11) of the steel member (10) in a state where the center is sagging downward due to the application of a vertical load and then the load is released. A cantilever girder characterized by comprising: a lower reinforcing plate (30) formed such that compressive stress acts on the upper part and tensile stress acts on the lower part of the steel member (10) after the upper reinforcing plate (20) is welded, the steel member (10) is inverted vertically and placed on the upper part of the lower flange (12), and after prestress is formed by the upper reinforcing plate (20), the center is welded in a state where sagging occurs downward due to the application of a separate vertical load, and then the load is released. Claim 4 An extended pedestrian bridge using a cantilever girder according to claim 3, comprising: a steel joist (220) arranged parallel to the upper portion of the cantilever girder (100); a composite material floor plate (240) arranged on the upper portion of the steel joist (220); and a connecting device part (280) connecting the cantilever girder (100) and the steel joist (220); wherein the cantilever girder (100) is characterized by having prestress introduced by an upper reinforcing plate (20) and a lower reinforcing plate (30). Claim 5 In claim 4, the extended pedestrian bridge comprises: a square tube-shaped steel joist (220) installed parallel to the upper part of the cantilever girder (100); a composite material floor plate (240) installed parallel to the upper part of the steel joist (220) in a vertical direction and having an anti-static and anti-slip layer (250) formed on its upper surface; a square tube-shaped handrail foundation frame (210) installed at one end or both ends of the composite material floor plate (240) installed on the upper part of the cantilever girder (100); a girder joist connecting clip (260) installed on the upper surface of the steel joist (220), a horizontal joist section (271) inserted into both wing sections (261) of the girder joist connecting clip (260), and a hanging section (272) of a circular spring (273) formed on both sides of the horizontal joist section (271) of the cantilever girder (100). A girder joist coupling device part (280) comprising a girder joist coupling spring (270) that is fitted and fixed at both corners and fixes the steel joist (220) to the cantilever girder (100); and a composite material floor plate (240) that is fixed on the steel joist (220) by fitting the insertion groove (241) of the composite material floor plate (240) into the horizontal insertion part (234) formed facing outward on both upper sides after being inserted into the steel joist (220). An extended pedestrian bridge including a deck fixing device (230) made of metal material of the shape.

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