JP2017166268A - Bridge falling prevention structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bridge falling prevention structure capable of suppressing as much as possible functional reduction in a bridge due to earthquake disaster with a simple construction.SOLUTION: There is provided a bridge falling prevention structure in which a bridge pier 11 and a bridge girder 12 of a bridge 1 are connected. In addition, it comprises a lower bracket 2 fixed onto a bridge axis surface 11a of the pier, an upper bracket 3 fixed onto a bridge axis inner surface 12a of the girder, a PC cable 4 connecting the lower bracket and the upper bracket, and shearing blocks 5 and 5 arranged on both sides in a bridge axis orthogonal direction X of the bridge girder in an upper surface 11b of the pier.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fall-off prevention structure for connecting a substructure such as a bridge pier or abutment to a superstructure such as a bridge girder.

  As disclosed in Patent Documents 1-3, in order to improve the seismic performance of existing bridges, a method for increasing the shear strength by winding a steel plate or reinforced concrete around the outer peripheral surface of the pier is known. Yes.

  Patent Document 1 describes an earthquake-resistant reinforcing device that can prevent a falling bridge due to an earthquake by connecting an abutment and a bridge girder with a belt bent by a deflection bracket. Furthermore, there is also disclosed a falling-bridge prevention structure belt that can prevent a bridge superstructure from flowing out even when a lifting force acts on a bridge girder due to a tsunami.

Japanese Unexamined Patent Publication No. 2016-23534 JP2011-99201A JP 2011-89275 A

  However, in a structure using only cables and belts, the amount of deformation until the function is exerted becomes large, so it is difficult to maintain the function of the bridge even if it can prevent a falling bridge or outflow. In other words, in order to secure a lifeline after the earthquake disaster and to quickly restore it, a bridge that can maintain the minimum functions even after a tsunami is required.

  In view of the above, an object of the present invention is to provide a structure for preventing a fallen bridge with a simple structure and capable of minimizing a decline in the function of the bridge due to an earthquake disaster.

  In order to achieve the above object, the falling bridge prevention structure of the present invention is a falling bridge prevention structure for connecting a bridge lower work and an upper work, and is a lower bracket fixed to a vertical plane in the bridge axis direction of the lower work. An upper bracket fixed to a vertical plane in the bridge axis direction of the upper work, a connecting material for connecting the lower bracket and the upper bracket, and both sides of the upper work in the direction perpendicular to the bridge axis on the lower work And a protrusion disposed on the surface.

  Here, the connecting material may be a PC steel material. Moreover, it can be set as the structure by which the shock-absorbing material is interposed between the said protrusion and the said bridge girder. Furthermore, the connecting material can be configured to be arranged vertically.

  In addition, the lower bracket may be fixed to the lower work with anchor bolts, and the upper bracket may be fixed to the upper work with anchor bolts.

  In the falling bridge prevention structure of the present invention configured as described above, the upper bracket and the lower bracket are fixed to the vertical plane in the bridge axis direction of the lower work and the upper work, and the lower bracket and the upper bracket are connected by the connecting material. In addition, protrusions are installed on both sides of the upper work in the direction perpendicular to the bridge axis on the lower work.

  In this way, with a simple configuration in which the upper and lower brackets are connected with a connecting material and the protrusions are installed on both sides of the upper work, it is possible to minimize the deterioration of the function of the bridge due to the earthquake disaster.

  Further, if the connecting material is a PC steel material, even if a lifting force acts on the connecting material due to a tsunami or the like and a strong tensile force acts temporarily on the connecting material, it can continue to exhibit the function of preventing a falling bridge without breaking.

  Furthermore, if an impact buffering material is interposed between the projection and the bridge girder, even if an impact force is applied due to a tsunami, the horizontal girder in the direction perpendicular to the bridge axis is counteracted without damaging the bridge girder. be able to.

  Further, if the connecting member is arranged vertically, it can react directly to a force in the vertical direction such as an uplift force as compared with a case where the connecting member is arranged bent or obliquely.

  And if it is the structure which fixes a lower bracket and an upper bracket with an anchor bolt, while being able to suppress the influence which acts on a lower work and an upper work to the minimum, it can be set as firm fixation.

It is a cross-sectional view for demonstrating the structure of the fallen bridge prevention structure part of this Embodiment. It is a longitudinal cross-sectional view for demonstrating the structure of the fallen bridge prevention structure part of this Embodiment. It is a 4th page explaining the structure of a lower bracket. It is a 4th page explaining the structure of an upper bracket. It is explanatory drawing which showed typically the force which acts on the fallen bridge prevention structure of this Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a schematic configuration of the bridge 1 described in the present embodiment in a cross-sectional view cut in the bridge axis orthogonal direction X and a vertical cross-sectional view cut in the bridge axis direction Y.

  The bridge 1 is mainly composed of a substructure such as a pier 11 and an abutment and a superstructure such as a bridge girder 12. Usually, the superstructure is installed on the substructure via a support part. In the present embodiment, a description will be given by taking as an example a configuration in which the ends of the bridge girder 12 in the bridge axis direction Y are placed on the rubber supports 13 and 13 installed on the upper surface 11b of the pier 11.

  The pier 11 illustrated in FIGS. 1 and 2 is constructed of reinforced concrete in a rectangular column shape having a substantially rectangular shape in plan view or a substantially oval shape in plan view. Here, a vertical plane that is a side surface in the bridge axis direction Y is defined as a bridge axis surface 11a.

  On the other hand, the bridge girder 12 illustrated in FIGS. 1 and 2 is a long reinforced concrete structure or a prestressed concrete structure that extends in the bridge axis direction Y. The bridge girder 12 includes a pair of main girder parts 121 and 121 provided in parallel with a gap in the bridge axis orthogonal direction X, and a horizontal girder part 122 provided on the pier 11 serving as an end in the bridge axis direction Y. It is mainly comprised by the slab 123 which forms the upper surface of the bridge girder 12. FIG.

  The cross beam portion 122 is provided so as to close the gap between the main beam portions 121 and 121 in a direction (bridge axis orthogonal direction X) substantially orthogonal to the extending direction of the main beam portions 121 and 121 (bridge axis direction Y). . A vertical surface that is exposed between the main girder portions 121 and 121 and serves as a side surface in the bridge axis direction Y of the horizontal girder portion 122 is defined as a bridge shaft inner surface 12a.

  FIG. 5 is a diagram schematically illustrating the fallen bridge prevention structure of the present embodiment. This falling-bridge prevention structure includes a lower bracket 2 fixed to the bridge shaft surface 11 a of the pier 11, an upper bracket 3 fixed to the bridge shaft inner surface 12 a of the bridge girder 12, and a connection that connects the lower bracket 2 and the upper bracket 3. It is mainly composed of the material (4) and the shear blocks 5 and 5 as protrusions installed on both sides of the bridge girder 12 in the bridge axis orthogonal direction X on the upper surface 11b of the pier 11.

  The lower bracket 2 and the upper bracket 3 are members fixed to the bridge pier 11 and the bridge girder 12 in order to fix the lower end 4a and the upper end 4b of the PC cable 4 as a connecting member.

  The shear block 5 is a member for suppressing relative displacement in the bridge axis orthogonal direction X of the bridge girder 12 with respect to the pier 11. For the shear block 5, a member having a large weight, such as concrete or mortar formed in a rectangular parallelepiped shape, can be used.

  This shear block 5 is fixed to the upper surface 11b of the pier 11 by post-construction anchors 52,. Further, an impact buffer 51 is interposed between the shear block 5 and the main girder 121 of the bridge girder 12. As the shock absorbing material 51, rubber, synthetic resin material or the like can be used.

  Next, detailed configurations of the lower bracket 2 and the upper bracket 3 will be described with reference to FIGS. First, the lower bracket 2 will be described with reference to the four views of FIG.

  FIG. 3 shows a front view of the lower bracket 2 at the center, a plan view and a bottom view of the lower bracket 2 above and below it, and a side view of the lower bracket 2 on the right side. The lower bracket 2 is manufactured by joining steel materials, such as a steel plate, by welding etc., for example.

  The lower bracket 2 is assembled on a rectangular base plate 24. A lower fixing portion 21 for fixing the lower end 4 a of the PC cable 4 is joined to the lower portion of the base plate 24.

  The lower fixing unit 21 joins the base of the member formed in a trapezoidal shape (hexagonal in the drawing) so as to be orthogonal to the base plate 24. The lower fixing portion 21 is formed with an insertion hole 212 for passing the PC cable 4.

  The lower surface side of the lower fixing portion 21 projecting in a shelf shape in the bridge axis direction Y is supported by right-angled triangular (pentagonal in the drawing) cane plates 211 and 211. For this reason, even if a large downward force is applied to the lower fixing unit 21, the deformation can be minimized.

  On the other hand, on the upper surface side of the lower fixing unit 21, a pair of guide plates 22 and 22 are provided substantially in parallel. The guide plate 22 is formed in a rectangular shape, and is joined to the base plate 24 and the lower fixing unit 21 with the longitudinal direction thereof set to the vertical direction. For this reason, even if a large upward force is applied to the lower fixing portion 21, the deformation can be minimized.

  A PC cable 4 is laid between the guide plates 22. The upper part between the guide plates 22 and 22 is closed by the front plate 221. Furthermore, the upper side surface of the guide plate 22 is reinforced by a pentagonal reinforcing plate 23 in plan view.

  Further, the base plate 24 has a plurality of bolt holes 241,. The bolt holes 241 are used when the lower bracket 2 is fixed to the pier 11 with anchor bolts 25 as shown in FIGS.

  FIG. 4 shows a front view of the upper bracket 3 at the center, a plan view and a bottom view of the upper bracket 3 above and below it, and a side view of the upper bracket 3 on the right side. The upper bracket 3 is manufactured by joining steel materials, such as a steel plate, by welding etc., for example.

  The upper fixing unit 31 joins the base of a member formed in a trapezoidal shape (hexagonal in the figure) so as to be orthogonal to the base plate 34. The upper fixing unit 31 is provided with an insertion hole 312 for allowing the PC cable 4 to pass therethrough.

  The upper fixing unit 31 protruding in a shelf shape in the bridge axis direction Y extends longer than the lower fixing unit 21 described above. That is, as shown in FIG. 2, the bridge shaft inner surface 12a to which the upper bracket 3 is attached is disposed at a position deeper than the bridge shaft surface 11a to which the lower bracket 2 is attached (the center side of the pier 11). In order to arrange vertically, the overhanging amount of the upper fixing unit 31 is increased.

  As shown in FIG. 4, the upper surface side of the upper fixing portion 31 is supported by suspension plates 311 and 311 having a right triangle shape (pentagonal shape in the figure). For this reason, even if a large upward force is applied to the upper fixing unit 31, the deformation can be minimized.

  On the other hand, on the lower surface side of the upper fixing unit 31, a pair of guide plates 32, 32 are provided substantially in parallel. The guide plate 32 is formed in a rectangular shape and joined to the base plate 34 and the upper fixing unit 31 in the vertical direction. For this reason, even if a large downward force is applied to the upper fixing unit 31, the deformation can be minimized.

  A PC cable 4 is laid between the guide plates 32. The lower part between the guide plates 32 and 32 is closed by a front plate 321 and an intermediate plate 322 is interposed inside. Further, the lower side surface of the guide plate 32 is reinforced by a pentagonal reinforcing plate 33 in plan view.

  In addition, a plurality of bolt holes 341,. The bolt holes 341 are used when the upper bracket 3 is fixed to the pier 11 with anchor bolts 35 as shown in FIGS.

  The PC cable 4 fixed to the lower bracket 2 and the upper bracket 3 is mainly composed of a plurality of PC steel strands that are PC steel materials. The outer periphery of the stranded wire of PC steel is covered with a covering material 43 and subjected to rust prevention treatment.

  In the vicinity of the lower end 4 a and the upper end 4 b of the PC cable 4, a screw groove is provided via a protective tube 44, and fixing is performed by the pressure bearing plate 41 and the nut 42. That is, the lower end 4 a or the upper end 4 b is passed through the hole of the support plate 41, the support plate 41 is brought into contact with the lower fixing unit 21 or the upper fixing unit 31, and the nut 42 is tightened to fix the plate.

  In addition, the PC cable 4 is disposed substantially at the center between the guide plates 22 and 22 in the lower bracket 2, and extends upward between the front plate 221 and the base plate 24. On the other hand, the PC cable 4 in the upper bracket 3 passes between the front plate 321 and the middle plate 322 and extends upward while passing through the approximate center between the guide plates 32 and 32.

Next, the construction method of the fallen bridge prevention structure of this Embodiment and the effect | action of a fallen bridge prevention structure are demonstrated.
This falling-bridge prevention structure can be provided on a newly installed bridge or an existing bridge 1. In the present embodiment, a case will be described in which an existing bridge 1 is provided with a falling bridge prevention structure for reinforcement.

  First, an anchor hole for attaching the lower bracket 2 is drilled from the bridge shaft surface 11a side near the upper end of the pier 11 (slightly below the upper surface 11b). The diameter of the anchor hole is set in accordance with the diameter of the anchor bolt 25.

  The drilling of the anchor hole is performed in accordance with the positions of the bolt holes 241,... Of the lower bracket 2, but the position of the main reinforcing bar of the pier 11 is avoided. After drilling, the base plate 24 of the lower bracket 2 is brought into contact with the bridge shaft surface 11a, and anchor bolts 25 are inserted into the anchor holes to be fixed.

  The anchor bolt 25 is fixed through an adhesive filled in the anchor hole, and the head of the anchor bolt 25 is fixed to the base plate 24 via a nut or the like. As a result, the lower bracket 2 is firmly fixed to the bridge shaft surface 11a of the pier 11.

  On the other hand, an anchor hole for attaching the upper bracket 3 is drilled from the bridge shaft inner surface 12a side of the cross beam portion 122 of the bridge beam 12. The diameter of the anchor hole is set in accordance with the diameter of the anchor bolt 35.

  The drilling of the anchor hole is performed in accordance with the positions of the bolt holes 341,... Of the upper bracket 3, but the position of the main reinforcing bar of the cross beam portion 122 is avoided. After drilling, the base plate 34 of the upper bracket 3 is brought into contact with the bridge shaft inner surface 12a, and anchor bolts 35 are inserted into the anchor holes to be fixed.

  Then, the pressure plate 41 is placed on the upper surface of the upper fixing unit 31 in accordance with the position of the insertion hole 312, and the PC cable 4 with the nut 42 attached to the upper end 4 b is passed through the insertion hole 312. The PC cable 4 is passed between the front plate 321 and the middle plate 322 through the guide plates 32 and 32.

  The PC cable 4 that hangs down on the pier 11 side passes between the front plate 221 and the base plate 24 and is laid between the guide plates 22 and 22. Then, the support plate 41 and the nut 42 are attached to the lower end 4 a of the PC cable 4 protruding from the insertion hole 212 from the lower surface side of the lower fixing portion 21, and the nut 42 is tightened.

  On the other hand, on the upper surface 11 b of the pier 11, the shear blocks 5 and 5 are installed on the outer surface side of the main beam portions 121 and 121, respectively. At this time, the shock absorbing material 51 is interposed between the outer side surface of the main beam part 121 and the side surface of the shear block 5. Further, the shear block 5 is fixed to the pier 11 by post-construction anchors 52,.

  When an earthquake occurs in the ground where the bridge 1 with the fall prevention structure constructed in this way is located, various forces as shown in FIG. 5 act. In the case of the existing bridge 1, a seismic structure is separately provided to counter the seismic force. However, with respect to the horizontal force H in the direction orthogonal to the bridge axis X, the weight of the shear block 5 and the post-installed anchor 52 are provided. , ... can be applied to shear resistance. That is, the existing load-bearing structure against the horizontal force and the shear block 5 cooperate to share the horizontal force H.

  Furthermore, it is possible to counter the force received by the bridge 1 due to a tsunami or flood, which is not taken into account in the design of the existing bridge 1, by providing the structure for preventing a falling bridge according to the present embodiment.

  When a tsunami or the like hits the bridge 1, an impact force or water pressure acts as a horizontal force H from the bridge axis orthogonal direction X. Further, due to the horizontal force H, a moment M in the direction in which the bridge girder 12 falls is applied around the rubber bearing 13. Further, from below the bridge girder 12, an uplift force V acts due to submersion or the like.

  In contrast to these forces, as for the horizontal force H, the force buffered by the impact buffer 51 acts on the shear block 5 from the bridge girder 12, but the shear block 5 becomes resistance and the bridge girder 12 The movement in the bridge axis orthogonal direction X is limited. As for the moment M, when the bridge girder 12 is inclined, the inclination is limited by contacting the shear blocks 5 and 5 on both sides of the bridge girder 12.

  Further, with respect to the lifting force V, the separation between the lower bracket 2 and the upper bracket 3 connected by the PC cable 4 does not widen when the bridge girder 12 is lifted. be able to.

  In the falling bridge prevention structure of the present embodiment configured as described above, the upper bracket 3 and the lower bracket 2 are fixed to the vertical surfaces (11a, 12a) of the bridge pier 11 and the bridge girder 12 in the bridge axis direction Y, and the PC cable 4 is used. The lower bracket 2 and the upper bracket 3 are connected. Further, on the upper surface 11 b of the bridge pier 11, shear blocks 5 and 5 are installed on both sides of the bridge girder 12 in the bridge axis orthogonal direction X.

  In this way, the upper and lower brackets (2, 3) are connected by the PC cable 4 and the shear blocks 5, 5 are installed on both sides of the bridge girder 12, so that the deterioration of the function of the bridge 1 due to the earthquake is minimized. Can be suppressed.

  That is, the contact between the shear block 5 and the bridge girder 12 can directly resist the horizontal force H and the moment M in the bridge axis orthogonal direction X. Further, by connecting the pier 11 and the bridge girder 12 by the PC cable 4, it is possible to resist the uplift force V caused by a tsunami or the like.

  For this reason, it becomes a structure with high sensitivity to the acting force (H, M, V), and it is possible to prevent the outflow of the falling bridge and the bridge girder 12 and to minimize the functional deterioration of the bridge 1 due to the earthquake disaster. Is possible.

  In the case of the PC cable 4, even if a lifting force V acts on the PC cable 4 due to a tsunami or the like and a strong tensile force acts temporarily on the PC cable 4, it is possible to continue exhibiting the function of preventing the falling bridge without breaking.

  Furthermore, if the shock absorbing material 51 is interposed between the shear block 5 and the bridge girder 12, even if an impact force is applied due to a tsunami or the like, the bridge girder 12 is not damaged and the bridge axis orthogonal direction X is not damaged. The horizontal force H can be countered.

  Further, if the PC cable 4 is arranged vertically, it can be opposed to the vertical lifting force V over the entire cross-sectional area. In short, compared with a connecting cable arranged in a bent or slanted manner, it can react directly to a vertical force such as the uplift V.

  Furthermore, the PC cable 4 can be easily replaced even after receiving a large force due to seismic force or tsunami or when it deteriorates over time. Further, the lower bracket 2 and the upper bracket 3 which are made of steel and fixed via the anchor bolts 25 and 35 can easily replace or repair a damaged member.

  Furthermore, if the bridge girder 12 is connected to the pier 11 with the PC cable 4, even if a large lifting force V acts, it can be strongly resisted within the range of elongation of the PC cable 4, thus increasing toughness. Can do.

  And if it is the structure which fixes the lower bracket 2 and the upper bracket 3 with the anchor bolts 25 and 35, while being able to suppress the influence which acts on the pier 11 and the bridge girder 12 only to the drilling of an anchor hole, it is strong Can be fixed.

  Further, as shown in FIG. 2, when the overhang amount of the upper bracket 3 is longer than the overhang amount of the lower bracket 2, the position of the cross beam portion 122 of the bridge girder 12 can be disposed inside the pier 11. In the existing bridge 1, when the positions of the bridge shaft surface 11a and the bridge shaft inner surface 12a are originally shifted as shown in the drawing, the upper and lower brackets (2, 3) can be attached as they are.

  On the other hand, when the bridge shaft surface 11a and the bridge shaft inner surface 12a are close to each other, the upper portion of the bridge pier 11 can be widened in the bridge shaft direction Y to cope with it. As a result, the girders by the upper surface 11b of the bridge pier 11 are widened, and it is possible to extend the length of the girders that serves as a function for preventing a falling bridge in an unexpected large-scale earthquake.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, the pier 11, the bridge girder 12, and the rubber bearing 13 described in the above embodiment are merely examples, and the present invention is not limited thereto, and the present invention is also applied to other forms of substructure, superstructure, and support section. can do. Moreover, although the case where the existing bridge 1 was reinforced was demonstrated in the said embodiment, it is not limited to this, The fall prevention structure of this invention can also be provided simultaneously at the time of construction of a new bridge.

  Furthermore, in the said embodiment, although PC cable 4 was demonstrated to the example as a connection material, it is not limited to this, PC steel materials, such as a PC steel rod, can also be used as a connection material. Moreover, the linear or rod-shaped member with high tensile force other than PC steel materials can also be made into a connection material.

  Moreover, in the said embodiment, although the case where the shear block 5 was installed as a protrusion was demonstrated, it is not limited to this, A protrusion is formed by fixing a steel block with the post-construction anchor 52. You can also

1 Bridge 11 Pier (Substructure)
11a Bridge axis surface (vertical surface)
12 Bridge girder (superstructure)
12a Bridge shaft inner surface (vertical surface)
2 Lower bracket 21 Lower fixing part 25 Anchor bolt 3 Upper bracket 31 Upper fixing part 35 Anchor bolt 4 PC cable (connecting material, PC steel)
5 Shear block (projection)
51 Impact buffer material X Bridge axis orthogonal direction Y Bridge axis direction

Claims (5)

A structure to prevent a falling bridge that connects a bridge substructure and a superstructure,
A lower bracket fixed to a vertical plane in the bridge axis direction of the substructure;
An upper bracket fixed to a vertical surface in the bridge axis direction of the superstructure,
A connecting member for connecting the lower bracket and the upper bracket;
A falling bridge prevention structure comprising: protrusions installed on both sides of the upper work in the direction perpendicular to the bridge axis on the lower work.   The fallen bridge prevention structure according to claim 1, wherein the connecting material is a PC steel material.   The falling bridge prevention structure according to claim 1, wherein an impact buffering material is interposed between the protrusion and the superstructure.   4. The falling bridge prevention structure according to claim 1, wherein the connecting member is arranged vertically.   The said lower bracket is being fixed to the said substructure by the anchor bolt, The said upper bracket is also being fixed to the said superstructure by the anchor bolt, The Claim 1 thru | or 4 characterized by the above-mentioned. Fall-bridge prevention structure.