Scaffold device for bridge maintenance and maintenance method for steel bridge

Abstract

To provide a scaffold device for bridge maintenance capable of sufficiently ventilating a work area for carrying out maintenance work of a bridge and improving the work environment of the work area, and a maintenance method for a steel bridge.SOLUTION: A work area 9 formed between a bottom plate part 103 of a bridge 101 and a hanging scaffold 2 is closed, air is introduced from the outside by an external air introduction device 31, and air is sucked from the work area 9 by an internal air discharge device 32 and discharged to the outside. Then, the air introduction amount by the external air introduction device 31 and the air suction amount by the internal air discharge device 32 are controlled so that the work area 9 is in a negative pressure state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a scaffolding device for bridge maintenance used in bridge maintenance work and a maintenance method for a steel bridge performed using the scaffolding device for bridge maintenance.

Background Art

[0002] Conventionally, maintenance work has been carried out on steel bridges to prevent corrosion due to rust or to repair damage such as cracks and fractures due to fatigue. The maintenance work is carried out on a temporary suspension scaffold installed directly below the bridge girder part of the steel bridge. Further, in the maintenance work, since blasting treatment is generally performed to remove rust and old paint films, etc., in order to prevent the dust generated by the blasting treatment from scattering, the working area between the suspension scaffold and the bridge girder part is closed with a sheet or the like.

[0003] On the other hand, in the above-mentioned maintenance work, anti-rust painting may be performed for the prevention of corrosion, etc., and when performing this painting, it is required to ventilate the working area. For example, Patent Document 1 proposes a sheet for repair work provided with an openable and closable ventilation port. If the working area is closed by such a conventional sheet for repair work, scattering of dust can be prevented, and the working area can be ventilated by opening the ventilation port.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, since the conventional configuration of Patent Document 1 described above only provides a ventilation opening, it is impossible to sufficiently ventilate organic solvents and the like used for painting. In addition, the closed work area becomes extremely severe working environment for workers because the temperature rises significantly due to the greenhouse effect in summer.

[0006] The present invention proposes a scaffolding device for bridge maintenance that can sufficiently ventilate a work area where maintenance work is performed and improve the working environment of the work area, and a maintenance method for steel bridges.

Means for Solving the Problems

[0007] The first aspect of the present invention is a hanging scaffold that is suspended below the bridge girder portion of a bridge and forms a work area for maintenance work between the scaffold and the bottom plate portion of the bridge, a closing cover provided around the work area to close the openings around the work area, an external air introduction means for introducing air from outside the work area into the work area, and an internal air discharge means for sucking air in the work area and discharging it outside the work area. The amount of air introduced by the external air introduction means and the amount of air sucked by the internal air discharge means are controlled so as to keep the work area in a negative pressure state. It is a scaffolding device for bridge maintenance characterized by this. Here, the negative pressure state of the work area can be accurately controlled by the air introduction amount indicating the amount of air introduced into the work area and the air suction amount indicating the amount of air sucked from the work area. On the other hand, if the internal air discharge means can discharge the air sucked from the work area without loss (or with only a slight loss), or if the correlation between the air suction amount and the air discharge amount is accurately determined, the air suction amount is determined by the air discharge amount, so the air discharge amount and the air suction amount can be used substantially synonymously.

[0008] In such a configuration, since the external air introduction means and the internal air discharge means can generate an air flow that reaches outside the work area from outside the work area through the inside of the work area, sufficient ventilation of the work area can be achieved. And, by making the air suction amount larger than the air introduction amount so as to keep the work area in a negative pressure state, organic solvents and the like generated in the work area can be efficiently and surely removed. Furthermore, the temperature rise in the work area in summer can be suppressed by the above-described air flow. Therefore, according to the configuration of the present invention, the working environment in the work area can be dramatically improved.

[0009] In the above-described scaffold device for bridge maintenance of the present invention, a configuration is proposed in which the internal air discharge means includes filter means for removing organic solvents and dust from the sucked air.

[0010] According to such a configuration, it is possible to prevent organic solvents and dust generated by maintenance work in the work area from being discharged outside the work area. Therefore, according to this configuration, while preventing the scattering of organic solvents and dust generated in the maintenance work to the outside, the working environment in the work area can be improved.

[0011] A second aspect of the present invention is a method for maintaining a steel bridge using the above-described first scaffold device for bridge maintenance of the present invention, wherein the scaffold device for bridge maintenance is installed on the steel bridge, and temperature and humidity management means for controlling the temperature and humidity of the work area closed by the scaffold device for bridge maintenance is installed in the work area, a scaffold preparation step of installing the scaffold device for bridge maintenance on the steel bridge, a blasting step of making the work area closed by the scaffold device for bridge maintenance in a negative pressure state and performing blasting treatment, a coating environment setting step of setting the temperature and humidity environment of the work area to a predetermined inorganic zinc-rich paint coating environment by the temperature and humidity management means, and a coating step of coating an inorganic zinc-rich paint on the surface of the steel bridge material exposed by the blasting treatment in the work area with the inorganic zinc-rich paint coating environment. It is a method for maintaining a steel bridge characterized by including. Here, the inorganic zinc-rich paint coating environment refers to an environment suitable for applying inorganic zinc-rich paint, indicating a temperature and humidity environment where the temperature is higher than 0 degrees and the humidity is higher than 50% without condensation (refer to Table-II.5.4 Coating Prohibition Conditions described in "Steel Road Bridge Coating and Corrosion Protection Handbook, Japan Road Association").

[0012] In such a construction method, since the inorganic zinc-rich paint is applied in a work area controlled under the inorganic zinc-rich paint coating environment, the surface of the steel bridge material can be stably coated with the inorganic zinc-rich paint. Here, the inorganic zinc-rich paint is a paint that can improve the anti-corrosion performance of the steel material by coating it on the steel. However, because the conditions of the coating environment (usage environment) of this inorganic zinc-rich paint are strict, it was generally used in a factory that cleared these conditions. According to the construction method of the present invention, since the work area can be controlled to the coating environment of the above conditions by the temperature and humidity control means, the surface of the steel bridge material can be coated with the inorganic zinc-rich paint, and the anti-corrosion performance of the steel bridge can be dramatically improved.

[0013] In addition, since the construction method of the present invention uses the scaffolding device for bridge maintenance of the present invention described above, the functions and effects of the scaffolding device for bridge maintenance are achieved.

Effects of the Invention

[0014] According to the scaffolding device for bridge maintenance of the present invention, the working environment of the work area where maintenance work is carried out can be dramatically improved.

[0015] According to the steel bridge maintenance construction method of the present invention, the anti-corrosion performance of the steel bridge can be improved by applying inorganic zinc-rich paint.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0017] An embodiment in which the scaffolding device 1 for bridge maintenance according to the present invention is embodied will be described below. As shown in FIGS. 1 to 3, the steel bridge 101 includes a plurality of main girder portions 102 arranged in parallel at a predetermined interval in the width direction, bridge piers (not shown) erected in the longitudinal direction to support the main girder portions 102, and a bottom plate portion 103 installed on the main girder portions 102. Ground covering portions 104, 104 are provided on both left and right side edges of the bottom plate portion 103. In this embodiment, the steel bridge 101 corresponds to the bridge according to the present invention, and the main girder portion 102 corresponds to the bridge girder portion according to the present invention.

[0018] The scaffolding device 1 for bridge maintenance includes a suspended scaffolding 2 suspended from the main girder portion 102 by a plurality of suspension chains 5, left and right movable panels 3, 3 rotatably disposed on both left and right side edges of the suspended scaffolding 2, and dustproof sheets (not shown) respectively stretched at both longitudinal ends of the suspended scaffolding 2. Since a conventionally known dustproof sheet can be applied, its details are omitted.

[0019] The suspended platform 2 of this embodiment includes a platform 11 of a beam structure formed by connecting a plurality of joists 12 forming a truss structure to a hub 13, and a plurality of plates 15 supported by the platform 11. The suspended platform 2 is suspended from the main girder portion 102 by a plurality of the suspension chains 5 respectively connected to each hub 13 of the platform 11. Such a suspended platform 2 can be assembled by horizontally rotating a plurality of joists 12 respectively connected to a plurality of hubs 13 for the platform 11 (horizontal rotation type assembly method), so that the safety in high-altitude work is improved. Further, since the platform 11 is constituted by the joists 12 of the truss structure, it has high load-bearing capacity and the interval of the suspension chains 5 can be widened, so that it is easy to handle large members and devices. Furthermore, since a plurality of plates 15 are laid without gaps to form a flat floor surface, there is also an advantage that it is easy to use a trolley or the like. Such a suspended platform 2 can be applied to the one registered in the "Ministry of Land, Infrastructure, Transport and Tourism NETIS: Registration Number TH-150007-VE", and is so-called a quick deck (preceding floor construction type floor system suspended platform).

[0020] On both left and right side edges of the suspended platform 2, the movable panel 3 is provided via a hinge member 21 so as to be rotatable in the left-right direction. The movable panel 3 includes a substantially rectangular frame (not shown) and a resin flat panel attached to the frame. And the longitudinal length dimension of the movable panel 3 substantially orthogonal to the longitudinal direction is set to a predetermined dimension longer than the height interval between the suspended platform 2 and the bottom plate portion 103. Thereby, in a state where the movable panel 3 is in the closed position, the upper part of the movable panel 3 abuts against the side edge of the ground covering portion 104 (see FIGS. 1(B) and 3). The hinge member 21 is disposed on the side edge of the suspended platform 2 and connected to the lower part of the movable panel 3, and the movable panel 3 can be rotated about a rotation axis (not shown) along the longitudinal direction. In the present embodiment, the above-described left-right direction is the same as the width direction of the steel bridge 101.

[0021] The left and right movable panels 3, 3 rotate about the rotation axis of the hinge member 6, and thus are vertically erected and the upper parts thereof abut against the outer parts of the floor covering parts 104, 104 in the closed position (FIG. 1(B), FIG. 3), and are position-converted to the open position (FIG. 1(A), FIG. 2) where they are inclined outward to the left and right from the closed position and separated from the floor covering parts 104, 104. When the left and right movable panels 3, 3 are in the closed position, the work area 9 is surrounded by the left and right movable panels 3, 3 and the above-described dust-proof sheet, and thus becomes a sealed space. On the other hand, when the left and right movable panels 3, 3 are in the open position, an upper part is opened between the movable panels 3, 3 and the floor covering parts 104, 104. In this state, the work area 9 becomes a space opened to the outside on both the left and right sides.

[0022] Caulking and curing are performed at the connecting parts of such movable panels 3 and the dust-proof sheet with the hanging support 2, the bottom plate part 103, and the floor covering part 104, and the airtightness of the work area 9 is improved in a state where the movable panels 3 are in the closed position. Incidentally, the closed cover according to the present invention is constituted by the movable panels 3 and the dust-proof sheet.

[0023] Further, the scaffold device 1 for bridge maintenance of the present embodiment includes panel opening / closing means (not shown) for position-converting the movable panels 3, 3 between the closed position and the open position. The panel opening / closing means includes a hydraulic cylinder for rotating the movable panels 3, 3 between the closed position and the open position, a holding chain for holding the movable panels 3, 3 between the closed position and the open position, and the like.

[0024] An air conditioner 33 is installed on the hanging support 2 as air conditioning equipment, and an external air introduction device 31 and an internal air discharge device 32 are installed as ventilation equipment. Here, the hanging support 2 of the present embodiment is constituted by a joist 12 having a truss structure (quick deck) and has high load-bearing performance, so that the air conditioner 33, the external air introduction device 31, and the internal air discharge device 32, each of which is a relatively heavy object, can be stably installed.

[0025] The air conditioner 33 is for controlling the temperature and humidity in the work area 9, and a relatively large-sized one is used. By controlling the temperature and humidity with this air conditioner 33, even when painting is carried out on rainy days or at low temperatures, the desired painting quality can be maintained, the drying period can be suppressed from extending, and it becomes easier to complete the maintenance work within the scheduled construction period. Also, since the temperature and humidity in the work area 9 can be kept in a state where it is easy for the operator to work, a decrease in work efficiency in summer or winter can be suppressed. This air conditioner 33 corresponds to the temperature and humidity control means according to the present invention.

[0026] The external air introduction device 31 is for introducing external air into the work area 9, and includes an air intake part (not shown) disposed outside the work area 9 for drawing in external air and an air introduction part (not shown) disposed inside the work area 9 for blowing in external air. And the external air introduction device 31 has a control function for controlling the amount of air introduced into the work area 9 (hereinafter, the air introduction amount), and can be set to a predetermined air introduction amount by the operation of the operator. This external air introduction device 31 corresponds to the external air introduction means according to the present invention.

[0027] The internal air discharge device 32 is for sucking air in the work area 9 and discharging it to the outside, and includes an air suction part (not shown) disposed inside the work area 9 for sucking internal air and an air discharge part (not shown) disposed outside the work area 9 for discharging internal air. And a filter (not shown) for removing organic solvents and dust is provided in the air suction part, preventing the organic solvents and dust from scattering to the outside. Since a filter known heretofore can be applied, details are omitted. Further, this internal air discharge device 32 has a control function for controlling the amount of air sucked in the work area 9 (hereinafter, the air suction amount), and can be set to a predetermined air suction amount by the operation of the operator. This internal air discharge device 32 corresponds to the internal air discharge means according to the present invention, and the filter corresponds to the filter means according to the present invention.

[0028] In this embodiment, it is preferable that the external air introduction device 31 is installed near one end in the longitudinal direction of the work area 9, and the internal air discharge device 32 is installed near the other end in the longitudinal direction. Thereby, it is easy to generate an air flow over the entire work area 9, and it is easy to keep the entire work area 9 in a negative pressure state.

[0029] The maintenance method of the steel bridge 101 implemented by installing the scaffolding device 1 for bridge maintenance of this embodiment will be described. This maintenance method corresponds to the steel bridge maintenance method according to the present invention. In the maintenance method of this embodiment, as shown in FIG. 4, first, a temporary curing facility is installed on the steel bridge 101 to be maintained (S101). Specifically, the above-mentioned scaffolding device 1 for bridge maintenance is installed on the steel bridge 101, and maintenance devices, an air conditioner 33, an external air introduction device 31, an internal air discharge device 32, a device for performing blasting treatment and shot peening treatment (not shown), and a painting device (not shown) are installed. Here, the scaffolding device 1 for bridge maintenance is installed in a state where the left and right movable panels 3, 3 are held in the open position. The step (S101) of installing such a temporary curing facility corresponds to the scaffolding preparation step according to the present invention.

[0030] After that, the type and thickness of the old paint film applied to the steel bridge 101 and the condition of the steel bridge 101 are investigated to identify the target parts that require repair (S102). Then, based on the results of this investigation, the procedure for the repair work and the preparation of the members required for the repair are carried out, and the type and injection speed of the grit used in the blasting treatment and the shot used in the shot peening treatment are determined. Incidentally, the step of S102 may be performed before S101.

[0031] Next, an area closing process is performed (S103) in which the left and right movable panels 3, 3 are rotated from the open position to the closed position and held at the closed position. This area closing process is carried out before the next blasting process, and positions the movable panels 3, 3 at the closed position to close the work area 9. Then, the external air introduction device 31 and the internal air discharge device 32 are driven, and the air conditioner 33 is also driven. Here, the external air introduction device 31 is controlled such that the air introduction amount per unit time is a predetermined value (for example, 100 m 2 / min), and the internal air discharge device 32 is controlled such that the air suction amount per unit time is a predetermined value greater than the air introduction amount (for example, 300 m 2 / min). By controlling the air introduction amount and the air suction amount in this way, the work area 9 is held in a negative pressure state. Also, by driving the air conditioner 33, the temperature and humidity of the work area 9 are managed.

[0032] After the area closing process, a blasting process is performed (S104). In the blasting process, blasting is executed according to the conditions such as the grit and injection speed determined in S102 to remove the old paint film, rust, etc. adhering to the surface of the main girder portion 102. Thereby, the material surface of the main girder portion 102 is exposed. Here, although dust is generated from the old paint film, rust, and used grit during the blasting process, since the blasting process is carried out in the work area 9 where the movable panels 3, 3 are held at the closed position and in a negative pressure state, it is possible to prevent these dusts from scattering to the outside. And these dusts are sequentially collected as described later. This blasting process and the area closing process correspond to the blasting process according to the present invention.

[0033] Next, a salt removal process (S105) is executed to precisely remove the salt adhering to the main girder portion 102 and the like. A laser beam can be used for this salt removal process.

[0034] Next, a shot peening process is performed (S106). In this embodiment, before the shot peening process, a replacement process is performed on the blasting device that has sprayed grit. In this replacement process, the shot determined in S102 is loaded instead of the grit so that it can be ejected. By performing shot peening in the shot peening process, the fatigue strength and stress corrosion cracking resistance of the material surface of the main girder portion 102 can be improved. Even in this shot peening process, since it is carried out in the working area 9 where the movable panels 3, 3 are held in the closed position and in a negative pressure state, it is possible to prevent the shot from scattering to the outside. Then, the used shot generated by the shot peening process is sequentially collected as will be described later.

[0035] After the shot peening process, the surface of the material on which the treatment has been performed is inspected (S107). This inspection process includes not only visual inspection but also, for example, comparison using an ISO8501 blasting photo album or roughness confirmation using a surface roughness measuring instrument. By this, it is checked whether there is any remaining unpeeled coating film, or whether the roughness of the material surface is within the standard, etc., and appropriate treatment is performed on the insufficient portions. Here, if it is determined to be qualified by this inspection, the next painting process is performed. On the other hand, if it is determined to be unqualified (if there are insufficient portions), the process returns to the blasting process (S104) and is repeated.

[0036] Next, a painting process is performed (S108). In the painting process, first, by controlling the air conditioner 33, the environment of the working area is maintained as an environment suitable for painting with an inorganic zinc-rich paint (inorganic zinc-rich paint painting environment). Here, the inorganic zinc-rich paint painting environment of this embodiment satisfies the conditions that the temperature is higher than 0 degree and not more than 40 degrees, and the humidity is higher than 50% and less than 100%, and is set to the temperature and humidity at which the operator can easily work in the working area as described above. While maintaining the working area in such an inorganic zinc-rich paint painting environment, heavy anti-corrosion painting is performed on the range where the blasting process was executed in S104. This heavy anti-corrosion painting is performed by applying an anti-rust coating with an inorganic zinc-rich paint as a primer, applying a fluororesin paint as an intermediate coat on top of it to protect the anti-rust coating, and further applying a top coat with a fluororesin paint on top of this. Thereby, a new paint film covering the material surface of the main girder portion 102 is formed. In this embodiment, the painting process corresponds to the painting environment setting process and the painting process according to the present invention.

[0037] The working area 9 where this painting process is performed is in an environment where the movable panels 3, 3 are held in the closed position, maintained in the inorganic zinc-rich paint painting environment, and in the negative pressure and ventilated environment. By performing the painting process in the working area 9 with such an environment, the inorganic zinc-rich paint can be stably painted, the organic solvent of the paint can be prevented from scattering to the outside, and furthermore, the operator can be suppressed from excessively absorbing the organic solvent.

[0038] When the painting process is completed, its confirmation is performed (S109). This confirmation includes not only the confirmation of the film thickness after the paint is dried, but also, for example, the confirmation of the wet film thickness using a wetness gauge during the painting operation. Also, such confirmation is performed not only after the top coat painting, but also during the primer painting and the intermediate coat painting. The completion of this painting confirmation completes the painting operation.

[0039] When all the painting-related operations are completed through such confirmation, an area opening process is performed (S110). In this area opening process, the external air introduction device 31, the internal air discharge device 32, and the air conditioner 33 are stopped, and the left and right movable panels 3, 3 are rotated from the closed position to the open position and held at the open position. Thereby, the work area 9 is opened to the left and right.

[0040] When the area opening process is completed, the site is tidied up (S111). Specifically, devices for maintenance, the air conditioner 33, the external air introduction device 31, the internal air discharge device 32, devices for performing blasting and shot peening, and the painting device are withdrawn, and the scaffolding device 1 for bridge maintenance is removed and recovered. The completion of such tidying up means the completion of all the processes in the maintenance method of the steel bridge 101.

[0041] Also, together with the processes of S101 to S111 described above, a dust collection process is executed (S120). Specifically, the used grit generated in the blasting process (S104), the used shot generated in the shot peening process (S106), and the dust including the old paint film and rust generated in each process are collected while being separated.

[0042] The scaffolding device 1 for bridge maintenance in this embodiment is provided with an external air introduction device 31 and an internal air discharge device 32 in a working area 9 closed by setting movable panels 3, 3 provided on the left and right of the hanging scaffold 2 to the closed position. During the period from the blasting process to the painting process, by making the air suction volume of the internal air discharge device 32 larger than the air introduction volume of the external air introduction device 31, the working area 9 is kept in a negative pressure state. Thereby, it is possible to prevent the dust generated in the blasting process and the shot peening process and the organic solvent used in the painting process from scattering to the outside, and since the ventilation of the working area 9 can be sufficiently performed, the dust and the organic solvent can be efficiently and surely removed. In addition, it is also possible to suppress the temperature rise of the working area 9 in summer. Further, in this embodiment, since the internal air discharge device 32 is provided with a filter, it is possible to prevent the dust and the organic solvent from scattering to the outside together with the air. For these reasons, according to the configuration of this embodiment, it is possible to prevent the scattering of dust and organic solvents generated in the maintenance work and to dramatically improve the working environment of the working area.

[0043] Also, in the configuration of this embodiment, since an air conditioner 33 is installed in the working area 9 to manage the temperature and humidity, the working environment of the working area 9 can be improved, and the painting quality can be stably maintained even on rainy days and at low temperatures. Due to such improvement of the working environment, the working efficiency is also improved, so that the construction period of the maintenance work can be shortened. Thereby, it is possible to contribute to the stabilization of the number of working days and the stabilization of the income of the workers, making it easier to secure workers and expecting an effect of suppressing job transfers to other industries.

[0044] Also, in the steel bridge maintenance method of this embodiment, since the painting process is performed while maintaining it in an inorganic zinc-rich paint painting environment suitable for the painting of the inorganic zinc-rich paint, the inorganic zinc-rich paint can be stably painted, and the anticorrosion performance of the steel bridge 101 can be dramatically improved. Specifically, due to the strict conditions of the painting environment, inorganic zinc-rich paint could not be used conventionally unless in a factory that could be accurately controlled under the temperature and humidity conditions. In this embodiment, as described above, the large air conditioner 33, which is a relatively heavy object, can be installed by the scaffolding device 1 for bridge maintenance, and the temperature and humidity in the working area can be accurately and stably controlled. Thus, the working area can be controlled as the inorganic zinc-rich paint painting environment. Thereby, the inorganic zinc-rich paint can be painted, and the anticorrosion performance can be remarkably improved as described above. If it is organic zinc-rich paint, it can be painted by using a relatively low-performance small air-conditioning facility. However, the organic zinc-rich paint is inferior in anticorrosion property compared with the inorganic zinc-rich paint. This also shows that the maintenance method of this embodiment is extremely excellent.

[0045] The present invention is not limited to the above-described embodiments, and can be appropriately changed within the scope not departing from the gist of the present invention. For example, the dimensional shapes of the respective parts in the embodiments can be appropriately changed. In the embodiment, the external air introduction device, the internal air discharge device, and the air conditioner are installed inside the working area (on the suspended scaffold). However, the present invention is not limited to this, and they may be installed outside the working area (for example, on the bottom plate part of the steel bridge). In the embodiment, the suspended scaffold is constituted by a quick deck. However, the present invention is not limited to this, and a suspended scaffold constituted by a single pipe, a suspension chain, a scaffold board, etc. may be used. In the case of this alternative-configured suspended scaffold, the external air introduction device, the internal air discharge device, and the air conditioner are installed on the bottom plate part of the steel bridge (outside the working area). In the embodiment, an opening / closing panel that opens and closes on the left and right of the suspended scaffold is provided. However, the present invention is not limited to this, and a configuration in which dust-proof sheets are provided on both the left and right sides without an opening / closing panel may be used. In this configuration, a dust-proof sheet is provided around the suspended scaffold to close the working area.

Explanation of Reference Numerals

[0046] 1 Scaffolding device for bridge maintenance 2 Suspended scaffold 3 Movable panel 9 Working area 31 External air introduction device 32 Internal air discharge device 101 Steel bridge 102 Main girder part 103 Bottom plate part

Claims

1. A suspension scaffold that is suspended below the bridge girder portion of a bridge and forms a work area for maintenance work between the scaffold and the bottom plate portion of the bridge, A closing cover provided around the work area to close the opening around the work area, External air introduction means for introducing air from outside the work area into the work area, Internal air discharge means for sucking air in the work area and discharging it outside the work area and is equipped with A scaffold device for bridge maintenance, characterized in that the air introduction amount by the external air introduction means and the air suction amount by the internal air discharge means are controlled so as to keep the work area in a negative pressure state.

2. The internal air discharge means is characterized in that it is provided with filter means for removing organic solvents and dust from the sucked air, and is the scaffold device for bridge maintenance according to Claim 1.

3. A maintenance method for a steel bridge using the scaffold device for bridge maintenance according to Claim 1 or Claim 2, A scaffold preparation step of installing the scaffold device for bridge maintenance on a steel bridge and installing temperature and humidity management means for controlling the temperature and humidity of the work area closed by the scaffold device for bridge maintenance in the work area, A blasting step of making the work area closed by the scaffold device for bridge maintenance in a negative pressure state and performing blasting treatment, A painting environment setting step of setting the temperature and humidity environment of the work area to a predetermined inorganic zinc-rich paint coating environment by the temperature and humidity management means, A painting step of painting an inorganic zinc-rich paint on the surface of the steel bridge material exposed by the blasting treatment in the work area with the inorganic zinc-rich paint coating environment and includes a maintenance method for a steel bridge, characterized in that it includes the above steps.

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