JP7699338B2 - Step prevention materials and bridges - Google Patents

Description

The present invention relates to a step prevention material that is installed on a bridge pier and prevents the bridge girder from displacing downward and thus prevents the formation of a step even when a situation arises in which the bridge girder cannot be adequately supported by the support part, and to a bridge having the step prevention material.

Bridge girders are often made of metals such as iron, and are subject to a certain degree of displacement due to expansion and contraction caused by temperature changes and vibrations caused by vehicle traffic. In order to absorb such displacement and prevent damage to the piers, the bridge piers and girders are generally connected via supports that are installed on the girders and have the property of elastically deforming when subjected to external forces.

However, in the event of a strong earthquake with large shaking, the bridge girder may be deformed or damaged beyond the displacement that the support can support, and the support may no longer be able to support the bridge girder at the specified height above the pier. This may result in the bridge girder falling from the support or otherwise displacing downward, creating a large step at the boundary between the top surface of the bridge girder deck and the adjacent road surface. In particular, in the event of such a strong earthquake, bridges used as road bridges are required to evacuate vehicles remaining on the bridge girder off the bridge and to allow emergency vehicles and other vehicles to pass so that transportation can be quickly restored to a healthy state, but areas where the bridge girder has displaced downward above the pier and a step has appeared in the road surface may hinder such transportation. It is generally said that a step of 50 to 100 mm on the road surface makes it difficult for emergency vehicles to pass.

As a result, it has been proposed to install step prevention materials on bridge piers (Non-Patent Document 1). Step prevention materials support the bridge girder at an appropriate height when an earthquake or other event occurs that makes it impossible for the bridge girder to be adequately supported by the bearings. By installing step prevention materials on existing bridges, steps (such as road surface steps) that occur in front of and behind the bridge girder in the event of a disaster such as an earthquake can be reduced.

“SE Block, step prevention structure”, [online], SE Corporation, [searched May 13, 2021], Internet <URL: http://se-kyoryokozo.jp/prod10-1.html>

However, the step prevention material described in Non-Patent Document 1 was made of steel to give it the mechanical strength to support the bridge girders, and was heavy. In order to install such a step prevention material, it was necessary to set up fixed scaffolding, and the installation work took a lot of time.

The object of the present invention is to provide a step prevention material that has the desired mechanical strength, is lightweight, and can be easily installed, and a bridge that includes this step prevention material.

The inventors discovered that by constructing the main body of the step prevention material from a fiber-reinforced resin composite using fibers with a tensile strength of 2000 MPa or more and forming the main body in a columnar or cylindrical shape, the weight of the step prevention material can be reduced and the mechanical strength of the step prevention material can be increased, leading to the completion of the present invention. More specifically, the present invention provides the following.

(1) A step prevention material that is installed at the top of a bridge pier near a support part that supports a bridge girder, and that supports the bridge girder together with or in place of the support part even in the event that a situation arises in which the support part is unable to adequately support the bridge girder, thereby suppressing the bridge girder from being displaced downward and preventing the occurrence of a step.
A step prevention material comprising a main body portion which is a fiber-reinforced resin composite having a columnar or tubular shape and which is composed of resin and a plurality of fibers having a tensile strength of 2000 MPa or more.

(2) The step prevention material described in (1) above, in which the main body portion has a first fiber layer in which the multiple fibers are arranged approximately parallel to a first direction.

(3) The step prevention material described in (2) above, in which the main body further has a second fiber layer arranged approximately parallel to a second direction different from the first direction.

(4) The step prevention material according to (1), (2) or (3) above, further comprising a base portion for fixing the main body portion to the pier.

(5) A step prevention material according to any one of (1) to (4) above, in which the fibers include at least one of carbon fibers, glass fibers, and aramid fibers.

(6) A step prevention material according to any one of (1) to (5) above, in which the content of the fibers constituting the step prevention material is in the range of 30% by mass or more and 70% by mass or less.

(7) A step prevention material according to any one of (1) to (6) above, in which the load capacity of the step prevention material is 2000 kN or more.

(8) The step prevention material described in any one of (1) to (7) above, wherein the bridge is used as a road bridge, and is configured so that when the bridge girder is supported by the step prevention material, the difference in height between the upper surface of the deck of the bridge girder and the height of the road surface adjacent to the upper surface of the deck of the bridge girder is 30 mm or less.

(9) A bridge having multiple piers, with girders that span the multiple piers being supported by bearings provided at the top of the piers, and a step prevention material is provided near the bearings provided at the top of the piers to support the girders together with or in place of the bearings, preventing the girders from displacing downward and preventing steps from occurring, even if a situation arises in which the bearings are no longer able to adequately support the girders, and the step prevention material is made of resin and multiple fibers with a tensile strength of 2000 MPa or more, and has a main body that is a fiber-reinforced resin composite having a columnar or tubular shape.

The present invention makes it possible to obtain a step prevention material that has the desired mechanical strength, is lightweight, and can be easily installed, as well as a bridge that includes this step prevention material.

1 is a front view of a main portion showing an example of the configuration of a bridge equipped with a step prevention material according to this embodiment. FIG. 1 is a side view of a main portion showing an example of the configuration of a bridge equipped with a step prevention material according to this embodiment. FIG. 1 is a side view of a key portion showing an example of the configuration of a bridge when the bridge girder is supported by a step prevention material according to this embodiment. FIG. 1 is a front view of a main portion showing a modified example of the bridge configuration provided with a step prevention material according to this embodiment. FIG. FIG. 2 is a side view showing an example of a bridge according to the present embodiment.

Specific embodiments of the present invention are described in detail below. Note that the present invention is not limited to the following embodiments, and various modifications are possible without departing from the gist of the present invention.

<Step prevention material>
Fig. 1 is a front view of a main part of an example of a bridge 1 provided with a step prevention member 10 according to the present embodiment. Fig. 2 is a side view of a main part of an example of a bridge 1 provided with a step prevention member 10 according to the present embodiment.

The step prevention material 10 according to this embodiment is used on the upper portion 131 of the pier 13 of the bridge 1, close to the support portion 15 that supports the bridge girder 14, and when a situation arises in which the support portion 15 is no longer able to adequately support the bridge girder 14, it prevents the bridge girder 14 from displacing downward, thereby preventing steps in front of and behind the bridge girder 14. Here, the step prevention material 10 is equipped with a main body portion 11 that is a fiber-reinforced resin composite having a columnar or tubular shape and is composed of resin and a plurality of fibers with a tensile strength of 2000 MPa or more.

By using such a step prevention material 10 having a main body 11 made of a fiber-reinforced resin composite using fibers with a tensile strength of 2000 MPa or more, the mechanical strength of the step prevention material 10, especially the main body 11, is increased. Therefore, even if a situation occurs in which the support part 15 cannot sufficiently support the bridge girder 14, the step prevention material 10 supports the bridge girder 14, and the step caused by the downward displacement of the bridge girder 14 can be suppressed. In addition, by providing the main body 11 made of such a fiber-reinforced resin composite, it is possible to make the main body 11 into a columnar or cylindrical shape, which reduces the weight of the step prevention material 10, and the step prevention material 10 can be easily installed on the bridge pier 13. Therefore, by using such a step prevention material 10, it is possible to provide a step prevention material 10 that has the desired mechanical strength, is lightweight, and can be easily installed, and a bridge 1 having this step prevention material 10.

The step prevention material 10 has at least a main body portion 11. It is preferable that the step prevention material 10 further has a base portion 12 that fixes the main body portion 11 to a pier 13.

(Main body)
The main body 11 is made of a fiber-reinforced resin composite that is composed of resin and a plurality of fibers having a tensile strength of 2000 MPa or more. By using such a fiber-reinforced resin composite, the mechanical strength of the main body 11 can be increased.

Of these, the fibers preferably include at least one of carbon fibers, glass fibers, and aramid fibers. Of these, it is more preferable to include carbon fibers from the viewpoint of ease of mixing with resin. These fibers are composed of fibers with a tensile strength of 2000 MPa or more, and in particular, it is preferable to include fibers with a tensile strength of 3500 MPa or more, and more preferably, to include fibers with a tensile strength of 4000 MPa or more. By using such fibers with high tensile strength to form a fiber-reinforced resin composite, the mechanical strength of the main body 11 is increased, so that the main body 11 can support the bridge girder 14 when the support part 15 can no longer sufficiently support the bridge girder 14. The upper limit of the tensile strength of these fibers is not particularly limited, but may be, for example, 7000 MPa.

Here, it is preferable that the multiple fibers contained in the main body 11 constitute a first fiber layer that is arranged approximately parallel to the first direction. At this time, it is more preferable that the multiple fibers each extend in a direction that intersects with the installation surface on the pier 13. In this way, by arranging the fibers contained in the main body 11 approximately parallel, the tensile strength of the main body 11 in the height direction is increased, so that even if the installation area on the pier 13 is limited, the bridge girder 14 can be supported more reliably. In addition, since more fibers can be included in the main body 11, it is also possible to further increase the mechanical strength of the main body 11.

It is also preferable that the multiple fibers contained in the main body 11 further constitute a second fiber layer in which the multiple fibers are aligned approximately parallel to a second direction different from the first direction described above. In this way, multiple fibers are aligned along multiple different directions, which provides high mechanical strength in all directions, thereby further increasing the reliability of supporting the bridge girder 14.

In addition, it is more preferable that the multiple fibers contained in the main body 11 extend continuously in a direction that intersects at approximately right angles with a plane parallel to the installation surface on the pier 13. At this time, it is even more preferable that one or both of the fibers constituting the first fiber layer and the fibers constituting the second fiber layer extend continuously in a direction that intersects at approximately right angles with a plane parallel to the installation surface on the pier 13. Here, the fiber "intersects at approximately right angles with a plane parallel to the installation surface" means that the direction in which the fiber extends intersects with the installation surface at an angle of 60° to 90° when viewed in a cross section perpendicular to the installation surface. In addition, from the viewpoint of further increasing the compressive strength of the step prevention material 10 in the direction perpendicular to the installation surface, this angle may be preferably 65° to 90°, more preferably 70° to 90°, and even more preferably 75° to 90°. Note that the angle of the fiber extension direction with respect to the installation surface when viewed in a cross section perpendicular to the installation surface is the angle when viewed at an acute angle other than 90°.

The total fiber content in the main body 11 is not particularly limited, but is preferably in the range of 30% by mass to 70% by mass, relative to 100% by mass of the total mass of the main body 11.

On the other hand, the resin contained in the step prevention material 10 can include one or more selected from epoxy resin, unsaturated polyester, vinyl ester, phenol, cyanate ester, polyimide, polyamide (PA), polycarbonate (PC), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). By covering the fibers with such a resin, the mechanical strength of the step prevention material 10 can be further increased without losing the weight-reducing effect of the fibers with high tensile strength.

The means for obtaining the main body 11 using carbon material and resin is not particularly limited, and may be, for example, an autoclave molding method, an RTM (resin transfer molding) molding method, a VaRTM (vacuum resin transfer molding) molding method, an SMC (sheet molding compound) method, a FW (filament winding) method, a sheet winding method, a pultrusion method, etc.

(Base part)
The base portion 12 is provided adjacent to the underside of the main body portion 11, and is configured so that the main body portion 11 can be fixed to the upper portion 131 of the pier 13. As a result, even if the main body portion 11 of the step prevention member 10 needs to support the bridge girder 14, the main body portion 11 is less likely to tilt relative to the pier 13, so that the bridge girder 14 can be supported more stably.

The material of the base portion 12 is not particularly limited as long as it can be joined to the main body portion 11. For example, the base portion 12 can be made of one or more materials selected from carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), acrylonitrile butadiene styrene copolymer (ABS), polypropylene (PP), polyvinyl chloride (PVC), polycarbonate (PC), and nylon 66.

The base portion 12 is preferably configured to have a portion that extends from the main body portion 11 along the installation surface on the pier 13. This makes it even more difficult for the main body portion 11 to tilt relative to the pier 13.

(Shape and characteristics of step prevention material)
From the viewpoint of reducing weight, the shape of the main body 11 of the step prevention material 10 is tubular, such as a cylinder or a square tube, or columnar, such as a cylinder or a square pillar. The size and shape of the step prevention material 10 are set within a range that can withstand a load greater than the load expected to be applied when supporting the bridge girder 14 on the pier 13, which is determined from the weight of the bridge girder 14, etc. Among these, from the viewpoint of reducing weight, it is preferable to set the size and shape of the step prevention material 10 so that it can withstand a load that is 10% to 30% greater than the load expected to be applied when supporting the bridge girder 14.

The step prevention material 10 according to this embodiment preferably has a load capacity of 2000 kN or more. As a result, even if the step prevention material 10 needs to support the bridge girder 14, the step prevention material 10 is less likely to be compressed in the height direction, so that steps caused by the downward displacement of the bridge girder 14 can be suppressed. There is no particular limit to the upper limit of the load capacity of the step prevention material 10, and it is possible to obtain a step prevention material 10 with a load capacity of, for example, 8000 kN.

(Location of step prevention materials)
The step prevention member 10 according to this embodiment is provided on the upper portion 131 of the pier 13 of the bridge 1, and is provided in a position close to the support portion 15 that supports the bridge girder 14. Here, the step prevention member 10 is preferably provided on the pier 13 on which the support portion 15 is provided, and more specifically, is preferably provided on the upper surface of the pier 13 on which the support portion 15 is provided, or on the upper surface of a retainer (edge widening bracket, not shown) extending from the upper surface of the pier 13. As a result, even if a situation occurs in which the support portion 15 cannot sufficiently support the bridge girder 14, the step prevention member 10 near the support portion 15 supports the bridge girder together with the support portion 15 or in place of the support portion 15, so that the balance of the load of the bridge girder 14 applied to the step prevention member 10 and the support portion 15 is prevented from changing significantly, and thus the inclination of the bridge girder 14 can be suppressed. At the same time, the step caused by the bridge girder 14 being displaced downward can be suppressed.

Here, as shown in Fig. 1 and Fig. 2, the step prevention material 10 is provided directly below the bridge girder 14, and preferably has a gap of size h1 between the bridge girder 14 and the step prevention material ₁₀ when the bridge girder 14 is supported by the support portion 15. By having a gap between the step prevention material 10 and the bridge girder 14, the support portion 15 can absorb the expansion and contraction and vibration of the bridge girder 14 when the bridge girder 14 is supported by the support portion 15. At the same time, as shown in Fig. 3, even when the support portion 15 cannot support the bridge girder 14 due to an earthquake or the like and the bridge girder 14 is supported by the step prevention material 10, the magnitude _h2 of the downward displacement of the deck of the bridge girder 14 can be kept at most within the range of the size of the gap _h1 .

In particular, when the bridge 1 is used as a road bridge, it is preferable to set the size of the gap _h1 between the step prevention material 10 and the bridge girder 14 to 30 mm or less. As a result, when the bridge girder 14 is supported by the step prevention material 10, the difference in height between the deck upper surface 141 of the bridge girder 14 and the height of the road surface 21 adjacent to the deck upper surface 141 of the bridge girder 14 (road surface step) falls within a range of 30 mm or less, so that running vehicles remaining on the deck upper surface 141 of the bridge girder 14 can be evacuated outside the bridge and emergency vehicles and the like can be allowed to run on the deck upper surface 141 of the bridge girder 14, thereby quickly restoring the transportation system to a healthy state.

On the other hand, the step prevention material 10 may be installed on the pier via a jack-up bracket. This makes it possible to suppress steps caused by downward displacement of the deck of the bridge girder 14 even if the area of the top surface of the pier 13 is restricted.

The step prevention material 10 according to this embodiment can be widely used in bridges 1 having a structure in which the bridge girder 14 is supported by the support parts 15. For example, it may be used in a bridge 1 having a bridge girder 14 made of a box girder as shown in FIG. 1, or in a bridge 1' having a bridge girder 14' made of a plate girder as shown in FIG. 4. Here, when used in a bridge 1 having a bridge girder 14 made of a box girder as shown in FIG. 1, it is preferable to provide a plurality of step prevention materials 10 in at least one of the width direction or extension direction of the bridge girder 14, and for example, it is preferable to provide them near each of the support parts 15a to 15e provided in the width direction of the bridge girder 14 (step prevention materials 10 near the support parts 15a and 15b are not shown in FIG. 1). Furthermore, when used in a bridge 1' having a bridge girder 14' made of plate girders as shown in Figure 4, it is preferable to provide multiple support parts 15 for each plate girder (support parts 15f to 15h) and provide step prevention materials 10 near each of these support parts 15. By providing multiple step prevention materials 10 in this way, the mechanical strength required of the step prevention material 10 can be reduced, making it possible to further reduce the weight of the step prevention material 10.

<How to install step prevention materials>
The construction method of the step prevention material 10 according to this embodiment is not particularly limited, and for example, the step prevention material 10 may be provided on the pier 13 of the bridge 1 by a joining process of joining the base portion 12 of the step prevention material 10 to the pier 13. In the construction method of this embodiment, the step prevention material 10 is made lighter, so that it can be installed on the pier 13 using a movable scaffolding without the need for a fixed scaffolding, and as a result, the step prevention material 10 can be easily installed.

The means for joining the base 12 of the step prevention material 10 to the pier 13 is not particularly limited, and may be a fastener such as an anchor bolt, or may be an adhesive. The step prevention material 10 may also be joined to the top of the pier 13 using both an adhesive and a fastener.

Here, it is preferable to use a methyl methacrylate (MMA)-based adhesive as the adhesive used to join the base 12 and the pier 13, as this is capable of joining different materials and has excellent fatigue resistance.

<Bridges>
5 is a side view showing an example of a bridge 1A according to this embodiment. The bridge 1A according to this embodiment has a plurality of piers 13, and a bridge girder 14 provided across these piers 13 is supported by the plurality of piers 13 by a support portion 15. This bridge 1A has a step prevention material 10 on each of the plurality of piers 13, which prevents a step from occurring before and after the bridge girder 14 by suppressing the bridge girder 14 from being displaced downward when a situation occurs in which the bridge girder 14 cannot be sufficiently supported by one or both of the support portions 15. Each of these step prevention materials 10 is composed of a resin and a plurality of fibers having a tensile strength of 2000 MPa or more, and has a main body portion 11 which is a fiber-reinforced resin composite having a columnar or tubular shape.

By using such step prevention materials 10 containing carbon material in the bridge 1A, each step prevention material 10 is made lighter, so that the step prevention materials 10 can be easily installed on multiple piers 13. This also gives the step prevention materials 10 the desired mechanical strength, so that even if a situation arises in which the bridge girder 14 cannot be sufficiently supported at one or both of the multiple support parts 15, steps caused by downward displacement of the bridge girder 14 can be suppressed.

Next, examples of the present invention will be described to further clarify the effects of the present invention, but the present invention is not limited to these.

[Example 1]
A first fiber layer was formed by using fibers (wire diameter: 5 μm to 8 μm, manufactured by Toray Industries, Inc., model number: P3252S-25) made of carbon fiber and having a tensile strength of 4900 MPa, and solidifying the fibers with an epoxy-based resin in a state in which the fibers are arranged approximately parallel in a first direction that forms an angle of 90° with respect to a plane parallel to the installation surface on the pier. Next, a second fiber layer was formed by solidifying the fibers with an epoxy-based resin in a state in which the fibers are arranged approximately parallel in a second direction that forms an angle of 45° with respect to a plane parallel to the installation surface on the pier, using the same fibers as the first fiber layer on the outside of the first fiber layer. The first fiber layer and the second fiber layer were repeatedly formed to form a cylindrical main body with an inner diameter of 200 mm and an outer diameter of 224 mm. The total content of fibers in the main body was 60% by mass with respect to the total mass of the main body, 100% by mass.

Next, along the bottom surface of the main body, a length of 320 mm and a width of 320 mm are
A rectangular base made of glass fiber reinforced plastic (GFRP) was placed, and the main body and base were bonded together using a structural adhesive (manufactured by ITW Performance Polymers & Fluids Japan, model number: Plexus AO420) to obtain a step prevention material.

The load capacity of the resulting step prevention material was measured using a static compression tester and found to be 3,000 kN.

Furthermore, when one end of a bridge girder (weight 1200t) consisting of a 20m wide, 35m long box girder used as a typical road bridge is supported by four step prevention members arranged in the width direction of the box girder, the load capacity (hereinafter referred to as "load capacity required to support the bridge girder") is calculated to be 2000kN or more by structural calculations. In this regard, the load capacity of the step prevention member of Example 1 of the present invention exceeded this value in all cases.

The maximum weight of the step prevention material that can be installed on a bridge pier using a mobile scaffolding, without the need for fixed scaffolding, is 30 kg. In this regard, the step prevention material of the present invention example 1 weighs 10.3 kg, so it can be installed on a bridge pier using a mobile scaffolding.

[Comparative Example 1]
A step prevention material was formed in the same manner as in Example 1 of the present invention, except that fibers having a tensile strength of less than 2000 MPa were used for the main body portion.

When the load capacity of the resulting step prevention material was measured using a static compression testing machine, it was found to be below the load capacity (2000 kN) required to support the bridge girder.

From the above, it was found that the step prevention material of Example 1 of the present invention has higher mechanical strength than the step prevention material of Comparative Example 1, and is lightweight and easy to install.

Although the embodiments and examples of the present invention have been described above, the above-described embodiments and examples do not limit the invention according to the claims. It should also be noted that not all of the combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

Reference Signs List 1, 1', 1A Bridge 10 Step prevention material 11 Main body 12 Base 13 Pier 131 Upper part of pier 14, 14' Bridge girder 141 Deck upper surface 15, 15a to 15h Support part 21 Road surface

Claims (8)

This step prevention material is installed at the top of a bridge pier near a support part that supports a bridge girder, and even if a situation arises in which the support part is unable to sufficiently support the bridge girder, it supports the bridge girder together with or in place of the support part, thereby suppressing the bridge girder from being displaced downward and preventing the occurrence of a step.
A main body portion which is a fiber reinforced resin composite having a columnar or cylindrical shape and which is composed of a resin and a plurality of fibers having a tensile strength of 2000 MPa or more ;
A base portion having an upper surface to which the bottom surface of the main body portion is joined and a lower surface to which the upper portion of the pier is joined;
It is composed of
A step prevention material , wherein the base portion has a portion extending outward from the joint surface with the main body portion . The step prevention material according to claim 1, wherein the main body portion has a first fiber layer in which the plurality of fibers are arranged substantially parallel to a first direction. The step prevention material according to claim 2, wherein the main body further has a second fiber layer arranged substantially parallel to a second direction different from the first direction. The step prevention material according to claim 1 , wherein the fibers include at least one of carbon fibers, glass fibers, and aramid fibers. The step prevention material according to claim 1 , wherein the content of the fibers constituting the step prevention material is in the range of 30% by mass or more and 70% by mass or less. The step prevention material according to claim 1 , wherein the load capacity of the step prevention material is 2000 kN or more. The bridge is used as a road bridge,
A step prevention material as described in any one of claims 1 to 6, configured so that when the bridge girder is supported by the step prevention material, the difference in height between the upper surface of the deck of the bridge girder and the height of the road surface adjacent to the upper surface of the deck of the bridge girder is 30 mm or less. A bridge having a plurality of piers, and a bridge girder provided across the plurality of piers is supported by a bearing provided at an upper portion of the piers,
Even if a situation arises in which the support section is no longer able to adequately support the bridge girder, a step prevention member is provided near the support section provided at the top of the pier, which supports the bridge girder together with or in place of the support section to suppress downward displacement of the bridge girder and prevent the occurrence of a step,
The step prevention material includes a main body portion which is a fiber-reinforced resin composite having a columnar or cylindrical shape and is composed of a resin and a plurality of fibers having a tensile strength of 2000 MPa or more ;
A base portion having an upper surface to which the bottom surface of the main body portion is joined and a lower surface to which the upper portion of the pier is joined;
It is composed of
A bridge , wherein the base portion has a portion extending outward from a joint surface with the main body portion .

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