JP5058015B2 - Steel slab bridge reinforcement equipment using compressed air - Google Patents

Description

  The present invention relates to an apparatus for reinforcing steel deck slab bridges that are built in a city, and more particularly to an apparatus for reinforcing steel deck slab bridges in order to prevent fatigue failure of steel deck decks.

Steel floor slab bridges are widely used on elevated roads and bridges in urban areas.
As shown in the perspective view from the lower side in FIG. 7, the steel floor slab is provided with a plurality of trough ribs having a substantially U-shaped cross section on the lower surface of the deck plate and arranged in parallel at predetermined intervals as vertical ribs. Lateral ribs and lateral getters are arranged at predetermined intervals in the transverse direction orthogonal to the trough ribs, and further main getters are arranged in the longitudinal direction through the transverse ribs and lateral getters, and are integrally joined by welding. .
Compared with RC slabs, steel slabs have the advantages that they are lighter, have fewer man-hours at the construction site, and can shorten the construction period.

However, there have been cases where fatigue cracks in steel decks are observed due to the increase in weight of traffic vehicles and traffic volume.
Fatigue cracks observed on steel slabs include fillet welds between deck plates and longitudinal ribs, intersections between longitudinal ribs and transverse ribs, welds between deck plates and vertical stiffeners, and butt welds between longitudinal ribs. What occurs in each part is prominent.

In particular, because the wheel load of the vehicle running on the road surface is loaded, the deck plate above the welding position of the longitudinal trough rib passed in the bridge axis direction is subjected to bending stress, and local stress is repeatedly generated due to the deck stress. Penetration cracks are likely to occur.
FIG. 8 is a cross-sectional view for explaining an example of a deck penetration type crack generated just above the truffle. A truffle, such as a U-rib, is welded to the lower surface of the steel deck deck plate, a base layer is formed on the upper surface by goose asphalt pavement, and a surface layer by asphalt pavement is formed thereon.

A crack penetrating the steel deck deck plate is likely to occur at a portion directly above the U-rib weld joint where bending stress is generated when a wheel load of the vehicle is loaded.
In this way, the deck penetration crack generated in the deck plate at the welded joint between the deck plate and the longitudinal rib is directly connected to the life of the bridge and is difficult to deal with.
In order to prevent such fatigue cracks and avoid the destruction of bridges, the development of appropriate techniques for reinforcing steel decks has become an issue.

  As for the road pavement of steel floor slab bridges, asphalt pavement is usually applied and the rigidity is low, so there is a method of changing to concrete pavement or mortar pavement as preventive maintenance against fatigue failure. However, when pavement changes are made to existing bridges, long-term traffic restrictions are imposed due to pavement work, which hinders economic activities. Therefore, the technology to repair and reinforce from the lower surface of the bridge attracts attention.

Patent Document 1 discloses a technique for enhancing the rigidity of a welded joint by injecting lightweight foamed concrete into a U-rib welded to the lower surface of a steel deck as a method of reinforcement from the lower surface of a bridge. ing. The disclosed construction method can improve the fatigue strength of the welded joint by constructing at a relatively low cost with mild traffic regulations.
However, in the disclosed construction method, it is difficult to confirm the concrete filling state, and the weight of the bridge body is increased greatly, resulting in problems of insufficient strength of the bridge body, piers and foundations.

Further, in Non-Patent Document 1, a reinforcing material such as CT shape steel or a plate material is fixed between U ribs with a high strength bolt, and the bottom portion of the U rib is cut open, and the reinforcing material is inserted into the U rib with a high strength bolt. A fixing method is disclosed.
This disclosed method can be applied under lane regulation and can effectively reduce the deformation of the steel slab and the stress in the axial direction of the bridge, but requires work from the road surface side and involves traffic regulation. In addition, the weight of the bridge becomes heavy and insufficient strength is a problem.
JP 2001-248114 A Hiroshi Kinoshita et al .: Proposal of reinforcement method for steel plate slab fatigue damage by U-rib rain gutter cut, Preprint of the 61st Annual Scientific Lecture, Japan Society of Civil Engineers, September 2006

  Accordingly, the problem to be solved by the present invention is to provide a steel slab bridge reinforcing device that is less likely to increase in weight of the bridge and is easy to apply.

The steel slab bridge reinforcing device of the present invention is applied to a steel slab bridge reinforced with a truffle from the lower surface of the steel deck slab plate, and by filling the space formed in the truffle with compressed air, The stress difference generated in the steel deck deck plate is reduced depending on the presence or absence of a vehicle traveling on the road surface.
According to the reinforcing device of the present invention, since the deck plate is pressed upward by the air pressure inside the trough rib, the deflection of the deck plate when the wheel load of the vehicle is loaded on this portion of the deck plate is reduced. Therefore, the bending stress generated in the truffle rib welded portion is reduced, and fatigue cracks are unlikely to occur.

When both ends of trough ribs are welded to the lateral ribs provided on the lower surface of the steel deck deck plate to form a sealed space, the compressed air is directly sealed in the formed sealed space, so that the deck plate The generated stress difference can be reduced.
Also, even when the space inside the truffle is not hermetically sealed, a stress difference due to the presence or absence of the vehicle can be obtained by opening an insertion port in a part of the truffle and inserting an air tube and filling the air tube with compressed air. Can be reduced.

The sealed space and the air tube are preferably provided with a tap connector for supplying compressed air with an air valve and a pressure gauge for detecting that the internal pressure is reduced due to air leakage or the like.
In addition, excessive air leakage in the enclosed space surrounded by the truffles is likely to mean that the deck plate crack has penetrated, so the installed pressure gauge can be used for fatigue crack management. it can.
Furthermore, a pressure alarm device that generates an alarm signal at a predetermined lower limit pressure value for supplying compressed air or monitoring a fatigue crack can be provided together with or instead of the pressure gauge.

Furthermore, a second air tube may be attached to an intermediate region sandwiched between the truffles so as to close the intermediate region. The second air tube has an upper surface attached to the back surface of the steel deck deck plate, an axial force member attached to the lower surface, and compressed air filled therein.
The second air tube exhibits an effect of reducing a difference in stress generated on the deck plate of the truffle rib weld portion generated when the wheel load of the vehicle is loaded on the steel deck deck plate in the middle region sandwiched between the truffles.
Furthermore, since the rigidity of the entire steel slab is improved, fatigue cracks at the intersecting portions of the transverse ribs are also alleviated.

The axial force member is affixed to the second air tube and may be fixed to a member fixed to the main getter of the horizontal rib or the steel deck, and is fixed to the adjacent truffle. Also good.
In addition to fixing the axial force member, a tension band is attached to the surface of the second air tube to stabilize the tube shape, and shear force due to vehicle wheel load loaded on the steel deck deck plate is transmitted. A reinforcing beam may be formed.
The tension band can be formed of a band-shaped sheet such as carbon fiber, glass fiber, or aramid fiber.
Instead of using the tension band, a 4-axis knitted fiber sheet parallel to the longitudinal axis and perpendicular to the longitudinal direction and 45 degrees in two directions may be wound around the second air tube.

The steel floor slab bridge reinforcement device of the present invention is lighter than conventional reinforcement structures with fewer members, so the increase in the weight of the bridge body is small, so new to the bridge body, substructure, foundation structure, etc. The need for reinforcement is low and construction is easy. Moreover, since installation work can be performed from the lower surface of the bridge, traffic regulation can be minimized.
Furthermore, in the device that directly uses the internal space of the truffle, it is only necessary to install the tap connector and pressure gauge, and in the device that uses the air tube, the materials used such as the air tube and the axial force member are lightweight, Easy to transport and install.

Hereinafter, the steel slab bridge reinforcing device of the present invention will be described in detail with reference to examples.
FIG. 1 is an elevational sectional view of an essential part of a steel floor slab bridge reinforcing device according to the first embodiment, FIG. 2 is a sectional view of a model used for FEM analysis for confirming the performance of the first embodiment, and FIG. 4 is a graph showing the analysis results, FIG. 4 is an elevational sectional view of an essential part of the steel deck slab reinforcement device according to the second embodiment, FIG. 5 is a side sectional view of the second embodiment, and FIG. 6 is a sectional view of the second embodiment. It is a side view which shows the example which took the load-proof performance improvement measure.

(First embodiment)
The steel slab bridge reinforcing device of the first embodiment shown in FIG. 1 is a steel slab bridge used for an elevated expressway and a bridge portion, and a U-rib or the like is provided on the lower surface of the steel slab deck plate 11. The present invention is applied to a steel deck slab bridge stiffened with trough ribs 12.
As described with reference to FIG. 7, the trough ribs 12 are welded to the horizontal ribs and the horizontal getters at both end faces, and form a sealed space 13 between the steel deck deck plate 11.

A tap connector 14 for connecting a compressed air supply hose (not shown) is attached to the sealed space 13. The tap connector 14 is equipped with an air valve that opens the flow path when compressed air is injected into the sealed space 13 and closes the flow path so as not to leak the compressed air filled in the sealed space 13 to the outside. If a check valve is used as the air valve, it can be sealed by simply pulling off the compressed air supply nozzle, which simplifies the compressed air filling operation and is convenient.
A pressure gauge 15 for measuring and displaying the internal pressure of the sealed space 13 is provided in the tap connector 14 or the sealed space 13 body.

The steel slab bridge reinforcing device of the present embodiment supports the steel slab deck plate 11 by pressing it from the inside by filling the sealed space 13 formed in the truffles 12 with compressed air.
Since the steel deck slab plate 11 is supported by air pressure from the lower surface, the difference in stress generated in the steel deck slab deck plate 11 can be reduced depending on the presence or absence of a vehicle traveling on the road surface.
The stress applied to the steel deck deck plate 11 when the wheel load of the vehicle is not loaded, the stress when the vehicle is loaded, and the stress difference before and after the vehicle loading are caused by the air pressure filled in the sealed space 13. Change.

The effect of the steel floor slab bridge reinforcing device of the present Example was confirmed by FEM analysis.
FIG. 2 is a cross-sectional view showing a partial model of a steel slab used in FEM analysis. The steel slab partial model is formed by welding a U-rib 12 having a thickness of 6 mm and an opening width of 350 mm to a steel floor slab deck plate 11 having a thickness of 12 mm to form a sealed space 13. The sealed space 13 is filled with compressed air. Thus, tension is introduced into the entire steel sheet to increase the restoring resistance. A load 16 of 30 kN was loaded as an external force equivalent to a vehicle wheel load in a region having a width of 200 mm in the center of the upper surface of the steel deck deck plate 11.

  In the FEM analysis, the air pressure charged in the sealed space 13 is changed, and the stress in the horizontal direction of the deck plate lower edge in the vicinity of the U-rib joint portion in the steel floor slab deck plate 11 supported by the compressed air is equivalent to the vehicle wheel load. Evaluation was made with the difference from the stress in the same direction generated when an external force was loaded.

FIG. 3 is a graph showing the analysis results.
As shown in the figure, the stress difference due to the presence or absence of load loading decreases as the internal pressure increases. However, if the stress applied to the steel slab deck plate 11 is excessive, overstress and fatigue of the steel slab deck plate 11 will be a problem, and therefore it is required to be within an appropriate range. When the air pressure is low, the stress value after loading becomes large, and when the air pressure is high, the stress value before loading becomes large.

Under this analysis condition, the stress in the vicinity of the truffle joint is small when there is no vehicle load and when the vehicle is loaded when compressed air is filled in the range of about 2.2 atmospheres and 2 to 2.5 atmospheres. It can be seen that the stress difference before and after loading becomes small and a stable reinforcing effect can be obtained.
As described above, by filling the steel floor slab bridge reinforcing device of this embodiment with appropriate compressed air, the deformation of the deck plate during loading of the passing vehicle is reduced, and the welded portion between the trough rib 12 and the steel floor slab deck plate 11 is reduced. The local stress in can be relaxed.
Thus, it could be confirmed that the steel plate slab bridge can be effectively reinforced by the reinforcing device of this example.

An inspection passage for management is installed under the steel slab bridge. The operator inspects the pressure gauge at appropriate time intervals. An air hose connected to the outlet is connected to the tap connector 14, and a necessary amount of compressed air is supplemented while looking at the pressure gauge 15.
When the pressure in the trough rib 12 is remarkably reduced or gradually decreased, there is a possibility that a through crack has occurred in the steel deck deck plate 11 and air leakage has occurred. Can be used for inspection of fatigue cracks in steel slabs.

The tap connector 14 and the pressure gauge 15 can be installed at a position where the pipe is pulled to the side of the bridge for each of the truffles 12 and can be handled from the road surface. If the tap connector 14 and the pressure gauge 15 are arranged on the bridge side, the work vehicle equipped with the compressor is brought close to the bridge side and stopped, so that the work can be efficiently performed from the vehicle.
It should be noted that a plurality of truffles 12 may be connected and filled with compressed air in common to perform pressure management.

The steel floor slab bridge reinforcing device of the present embodiment can be easily configured by installing the tap connector 14 and the pressure gauge 15 on the trough rib 12. For example, a small hole is drilled in the bottom surface of the truffle 12 and the root of the tap connector 14 is inserted and fixed by a nut or welding. The pressure gauge 15 can also be incorporated in the tap connector 14.
Therefore, even when applied to an existing bridge, it is not necessary to regulate traffic on the upper surface of the bridge, and the installation work can be completed in a very short period of time.

(Second embodiment)
The steel floor slab bridge reinforcing device of the second embodiment according to the present invention is compressed by attaching an air tube to an intermediate region sandwiched between truffles in addition to the configuration of the steel floor slab bridge reinforcing device of the first embodiment. The steel slab bridge is further reinforced by filling with air and reducing the stress in the intermediate region.

  As shown in the elevation view of FIG. 4 and the side view of FIG. 5, an air tube 21 is installed in the middle region of the steel slab truffle 12 and the truffle 12, and the compressed air is filled to pass through the middle region of the truffle 12. The deformation at the time of vehicle loading is reduced, and the local stress at the welded portion between the truffles 12 and the steel deck deck plate 11 is relieved.

  The air tube 21 is made of rubber or a polymer fiber sheet, and the sticking portion 22 in contact with the steel deck deck plate 11 and the trough rib 12 is bonded with an epoxy resin adhesive. An axial force member 23 is attached to the lower surface of the air tube 21. The axial force member 23 is a hard plate that is light and difficult to deform, such as an FRP (fiber reinforced plastics) plate, and adds rigidity to the air tube 21 to resist bending deformation. In addition, a plate perpendicular to the axial force member surface may be formed on the axial force member 23 to form a reinforcing rib 24 to increase the deformation resistance force. The reinforcing rib 24 is formed of a hard plate such as FRP.

  The axial force member 23 is fixed with respect to the steel deck slab deck plate 11 by fixing it with adhesives or bolts to the cradles 18 respectively attached to the lateral ribs 17 or the lateral getters located at both ends of the air tube 21. It is fixed. The axial force member 23 may be attached to the air tube 21 and fixed to the adjacent traffic rib 12 or may be fixed using a support member from the main getter of the steel deck. Reference numeral 19 in the figure indicates a longitudinal rib such as a truffle.

The air tube 21 is provided with the tap connector 14 and the pressure gauge 15 used in the first embodiment, so that the inside of the air tube can be pressurized and the internal pressure can be managed.
It goes without saying that the tap connector 14 and the pressure gauge 15 of the air tube 21 can also be pulled out by piping and installed on the bridge side.

When the compressed air is filled into the air tube 21 through the tap connector 14, the internal pressure rises, but since the axial force member 23 spatially fixed exists on the lower surface, the steel floor is similar to the reinforcing device of the first embodiment. The plate deck plate 11 is pressed upward to reduce the depression of the steel deck plate plate 11 when there is a passing vehicle. Therefore, the difference in stress due to the presence or absence of vehicle loading is alleviated, and the steel deck deck plate 11 can be effectively reinforced.
However, in the reinforcing method using the air tube 21 in the second embodiment, the compressed air is shielded by the surface layer film of the air tube 21, so that the internal pressure is monitored and the cracks generated in the steel deck deck plate 11 are detected. It cannot be used for inspection.

  The air tube 21 of this embodiment can be formed of a film made of a material such as rubber or FRP (fiber reinforced plastic), vinyl chloride, or polyethylene. Moreover, the fiber base material which coated resin can be used. In particular, the fiber may be formed of a 4-axis knitted fiber sheet parallel to, perpendicular to the axis, and inclined at 45 degrees in two directions.

In order to install the air tube 21 in the steel floor slab bridge reinforcing device of the present embodiment, the cradle 18 is installed on the lateral rib 17 in the span where the air tube 21 is installed, and the axial force member 23, the tap connector 14, The air tube 21 to which the pressure gauge 15 is attached is prepared, the air tube 21 is attached to the back side of the steel deck deck plate 11 with an adhesive, and the axial force member 23 may be fixed to the cradle 18.
Therefore, even when applied to an existing bridge, construction may be performed on the lower surface of the bridge, and installation can be performed in a very short period of time.

FIG. 6 is a side view of a steel slab bridge reinforcing device in which a shearing force is transmitted by a tension band 25 attached to the surface of the air tube 21.
As shown in FIG. 6, the air tube 21 is sandwiched between the lateral ribs 17 and the lateral getters, and the surfaces in contact with the steel deck deck plate 11, the adjacent U ribs, the lateral ribs 17 and the like are adhered to these surfaces with an adhesive. .

A tension band 25 such as a tension cable or tension tape is attached to the surface of the air tube 21. A belt-like sheet material such as carbon fiber, glass fiber, or aramid fiber can be used for the tension band 25.
In addition, a high-reinforcing device capable of transmitting a shearing force in the same manner can be configured by wrapping a fiber sheet of 4-axis knitting in which fibers are parallel, perpendicular to the axis and inclined at 45 degrees in two directions around the air tube 21. it can.
A set of a tap connector 14 and a pressure gauge 15 is attached to the lower surface of the air tube 21.

  One tension band 25 is fixed to the upper ends of both ends of the air tube 21, and a pair of spiral bands wound in a spiral shape toward the lower side of the center is used. Further, for example, as shown by reference numeral 26, one in which one end of the tension band is fixed to the upper end of the end of the air tube 21 and wound toward the upper center can be used.

When the air tube 21 is filled with compressed air, the air tube 21 swells and a tensile force acts on the tension bands 25 and 26 to transmit the shearing force of the air tube 21, thereby suppressing the deflection of the steel deck deck plate 11. The mechanism reduces stress.
It goes without saying that the arrangement method and the number of the tension bands can be changed according to the required reinforcement performance.
The air tube 21 in the steel slab bridge reinforcing device of this embodiment is simple and convenient to carry and install because most of the material is lightweight and flexible.

It is principal part elevation sectional drawing of the steel floor slab bridge reinforcement apparatus which concerns on 1st Example of this invention. It is sectional drawing of the model used for the FEM analysis which confirms the performance of 1st Example. It is a graph which shows a FEM analysis result. It is principal part elevation sectional drawing of the steel floor slab bridge reinforcement apparatus which concerns on 2nd Example of this invention. It is side surface sectional drawing of 2nd Example shown in FIG. It is a side view which shows the example which applied the load-proof performance improvement measure of 2nd Example. It is the perspective view which looked at the steel floor slab made into object by this invention from the lower side. It is sectional drawing explaining the example of the deck penetration type crack generated just above trough rib.

Explanation of symbols

10 Steel deck slab 11 Steel deck slab deck plate 12 Trough rib (U rib)
Reference Signs List 13 Sealed space 14 Tap connector 15 Pressure gauge 16 External force equivalent to vehicle wheel load 17 Lateral rib 18 Receiving base 19 Vertical rib 21 Air tube 22 Adhering portion 23 Axial force member 24 Reinforcement ribs 25 and 26 Tension band

Claims (10)

In steel deck slab bridges reinforced with truffles from the bottom of the steel deck deck plate, the stress generated in the steel deck deck plate by the vehicle traveling on the road surface by filling the sealed space formed in the truffle with compressed air Steel floor slab bridge reinforcement device characterized by reducing the difference. The steel-slab slab bridge according to claim 1, wherein the sealed space is a space sealed by welding both ends of the trough rib to lateral ribs provided on a lower surface of the steel-slab deck plate. Reinforcement device. The steel floor slab bridge reinforcing device according to claim 1, wherein the sealed space is formed by inserting an air tube into a space formed in the truffle. 4. The sealed space according to claim 1, further comprising an air valve provided with a valve for shutting off a flow of compressed air and connected to a compressed air supply pipe, and a pressure gauge for displaying the pressure in the trough rib. Steel floor slab bridge reinforcement device as described. The steel floor slab bridge reinforcing device according to any one of claims 1 to 4, further comprising a pressure alarm that generates an alarm signal when the pressure in the sealed space reaches a lower limit set value. A second air tube is mounted so as to block an intermediate region sandwiched between the truffles, and the second air tube has an upper surface adhered to the back surface of the steel deck deck plate, and a lower surface. By attaching an axial force member and filling compressed air into the second air tube, stress generated in the steel deck deck plate in the intermediate region and generated in the steel deck deck plate at the trough rib 6. The steel slab bridge reinforcing device according to claim 1, wherein a difference in stress to be reduced is reduced. 7. The steel according to claim 6, wherein the second air tube is provided with a valve that shuts off the flow of compressed air, an air valve that can be connected to a compressed air supply pipe, and a pressure gauge that displays the pressure in the trough rib. Floor slab bridge reinforcement device. The steel floor according to claim 6 or 7, wherein the second air tube having the axial force member is supported by a cradle or the like disposed on a lateral rib and is fixed between the adjacent truffles. Plate bridge reinforcement device. 7. The steel deck slab reinforcement device according to claim 6, wherein a tube shape into which air pressure is introduced is stabilized by obliquely attaching a tension band to the surface of the second air tube, and the steel deck is loaded on the steel deck deck plate. A steel floor slab bridge reinforcing device that forms a reinforcing beam by transmitting a shearing force caused by a vehicle wheel load. 10. The fiber sheet according to claim 9, wherein, instead of using the tension band, a four-axis knitted fiber sheet parallel to the longitudinal axis and perpendicular to the longitudinal direction and 45 degrees in two directions is wound around the second air tube. Steel slab bridge reinforcement device.

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