JP2013249617A - Bridge - Google Patents

Abstract

An object of the present invention is to prevent a problem that the upper structure is washed away by reducing the load applied to the upper structure by collapsing the rail when the wave force acts on the bridge and reducing the height dimension of the upper structure.
An upper structure having a bridge girder on a bridge pier, a floor slab 3 provided on the bridge girder, and a rail 4 provided along the longitudinal direction of the floor slab 3 on the upper side in the width direction of the floor slab 3. 5 having a shear pin structure 10 that receives a horizontal force by fitting each other vertically between the upper surface 3a of the floor slab 3 and the lower surface 4a of the rail 4; By providing the vertical reinforcing bars 7 extending vertically between the inside of the rail 4 and the inside of the floor slab 3 at the inner side in the width direction than the shear pin structure 10, wave force acts on the rail from the outside in the width direction. In the meantime, in the vicinity of the boundary S between the rail 4 and the floor slab 3, the rail 4 has a bent fulcrum 20 that bends with the vertical reinforcing bar 7 as a fulcrum.
[Selection] Figure 1

Description

  The present invention relates to a bridge that can reduce wave force caused by a tsunami or the like.

  A general bridge is composed of a bridge girder and a floor slab provided on the bridge girder, and a floor slab length above both ends of the floor slab in the width direction. And an upper structure having a handrail projecting in a direction.

  The rails provided on both upper sides of the width direction of the floor slab are for preventing a vehicle traveling on the floor slab from jumping out of the floor slab, and the rail and the floor slab are provided between each other. It is firmly fixed by a strength member such as (see Patent Documents 1 and 2, etc.).

  When forming concrete railings, a method of forming the railings integrally with the floor slab by placing concrete on the floor slab through a formwork, and fixing the railings of precast concrete on the floor slab on site It is roughly divided into construction methods.

Japanese Patent Application Laid-Open No. 08-269911 Japanese Patent Laid-Open No. 06-313304

  As a result of the tsunami generated by a huge earthquake acting on the bridge, the superstructure consisting of bridge girders, floor slabs and railings was washed away by the tsunami wave force, resulting in delays in the recovery work of the surrounding disaster. It has occurred. Also, the flow of long structures such as the superstructure of bridges can be a threat to surrounding structures.

  The current bridge design standards do not assume that the tsunami will act on the superstructure, and the fact that the tsunami force has not been designed is thought to have led to the loss of the superstructure. . At present, there is a structure that prevents the falling bridge from being installed with a structure that connects the upper structure to the lower structure and a structure that connects the upper structure to each other in the direction of the bridge axis, which is the longitudinal direction of the bridge. Basically, it was assumed that the bridge fell in the direction of the bridge axis, and for this reason, it was not possible to prevent a fall bridge (runaway) against wave forces perpendicular to the bridge axis like a tsunami. it is conceivable that.

  In addition to the wave force caused by the tsunami, there is a possibility that the superstructure will be lost due to storm surges and flood wave forces as well.

  In order to solve the problem of the bridge girder being washed away, measures to firmly fix the bridge girder to the pier can be considered. In this case, it is necessary to design to withstand a large load (wave force) that causes the superstructure to be washed away, but by fixing the bridge girder to the pier with extremely high strength, the superstructure can be washed away. Even if it can be prevented, the pier may be destroyed this time.

  For this reason, if the load received by the upper structure when the tsunami wave force acts on the upper structure can reduce the possibility of the upper structure being washed away, and the bridge girder is fixed to the pier. The fixing strength to be reduced can also be reduced.

  The present invention has been made in view of the above problems, and when the wave force is applied to the bridge, the railing collapses and the height dimension of the upper structure is reduced, thereby reducing the load received by the upper structure. It is intended to provide a bridge that prevents the problem of being washed away.

The present invention comprises an upper structure having a bridge girder on a bridge pier, a floor slab provided on the bridge girder, and a rail provided along the longitudinal direction of the floor slab on the upper side in the width direction of the floor slab. A bridge,
Between the upper surface of the floor slab and the lower surface of the railing has a shear pin structure that receives a horizontal force by fitting each other vertically.
When a wave force acts on the balustrade from the outside in the width direction by providing a vertical reinforcing bar arranged extending vertically between the inside of the balustrade and the inside of the floor slab at the inner side in the width direction than the shear pin structure Further, the present invention relates to a bridge characterized by having a bent fulcrum that bends with the vertical rebar as a fulcrum in the vicinity of the border between the rail and the floor slab.

  In the bridge, the bending fulcrum includes the vertical reinforcing bar arranged vertically extending between the inside of the railing and the inside of the floor slab, and the lower inside inside the width direction of the floor slab from the upper inside of the railing The inclined reinforcing bar arranged to extend obliquely toward may have a menase hinge structure that crosses in the vicinity of the border between the railing and the floor slab.

  In the bridge, the railing preferably includes a ground cover.

  Further, in the bridge, the shear pin structure is formed of concrete on a protruding portion of the reinforcing bar by protruding a reinforcing bar provided on the floor slab and the railing on either the upper surface of the floor slab or the lower surface of the railing. It is preferable that a convex portion and a concave portion formed so as to be fitted to the convex portion are provided on one of the upper surface of the floor slab and the lower surface of the rail.

  Further, the bridge includes a fairing having a height including the bridge girder and the floor slab at a position in the width direction outside of the superstructure, and having a shape in which a middle portion in the height direction projects outward. preferable.

  According to the present invention, the rail is held on the floor slab by the shear pin structure against a load caused by a vehicle collision or the like acting on the rail from the inside, and on the other hand, it acts on the rail from the outside. For wave forces, the shear pin structure is disengaged and the railing is folded around the folding fulcrum at the boundary with the floor slab, causing it to collapse to the inside of the floor slab and the height of the superstructure to be reduced As a result, the load received by the upper structure can be reduced, so that an excellent effect of reducing the problem of the upper structure being washed away can be obtained.

(A) is the cut front view of the principal part which shows one Example of the bridge of this invention, (b) is the front view which expanded and showed an example of the shear pin structure of (a). It is an II-II direction arrow directional view of Drawing 1 (a). (A) is the cut front view which looked at FIG. 2 from the III-III direction, (b) is the cut front view which shows the state in which the handrail of FIG. 1 collapsed by the wave force. (A) is the cutting front view of the principal part which shows the other Example of the bridge of this invention, (b) is the cutting front view which shows the state which the handrail of (a) collapsed by the wave force. It is a graph which shows the result of having performed the wave force analysis of the superstructure. (A) is the whole front view of one Example of the bridge of this invention, (b) is the whole front view which shows the Example which installed the fairing in the width direction outer side position of the upper structure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 6A is an overall front view showing an embodiment of a bridge according to the present invention. In FIG. 6, reference numeral 1 denotes a pier as a substructure standing on the ground at a predetermined interval. Is composed of a bridge girder 2, a floor slab 3 provided on the bridge girder 2, and an upper structure 4 provided on the upper side in the width direction of the floor slab 3 along the longitudinal direction of the floor slab 3. 5 is provided. The bridge girder 2 in the illustrated example is a steel plate girder in which main girder 2a made of an I-shaped steel plate extending in the longitudinal direction is arranged at a predetermined interval in the width direction of the bridge, but the bridge girder 2 extends in the longitudinal direction. A steel box girder having a main girder having a box-shaped cross section or a concrete girder may be used. In FIG. 6A, reference numeral 18 denotes a support provided between the pier 1 and the bridge girder 2.

  As shown in FIGS. 1 to 3, the floor slab 3 and the balustrade 4 are concrete structures in which reinforcing bars are arranged inside. 6 is integrally formed, and the rail 4 includes a ground cover 6.

  As shown in FIG. 1 (a), at the position below the upper surface 6 a of the ground cover 6 in the cross section of the rail 4, the inside of the rail 4 is within the ground cover 6 (inward in the width direction of the floor slab 3 After the extension, the vertical reinforcing bars 7 extending downward in the ground cover 6 and fixed inside the floor slab 3 are arranged. The boundary S between the lower surface 4a of the rail 4 and the upper surface 3a of the floor slab 3 is only connected by the vertical reinforcing bar 7, and therefore when wave force acts on the rail 4 from the outside in the width direction. The rail 4 forms a bent fulcrum 20 that bends with the vertical reinforcing bar 7 as a fulcrum at a position near the boundary S with the floor slab 3.

  A horizontal direction force is received by fitting each other vertically in the width direction outer side position than the longitudinal reinforcement 7 in the boundary portion S between the upper surface 3a of the floor slab 3 and the lower surface of the rail 4a. The shear pin structure 10 is provided. In the shear pin structure 10, as shown in FIG. 1B, a rebar 11 protruding upward from the inside of the floor slab 3 is provided on the upper surface 3a of the floor slab 3, and the protruding portion of the rebar 11 is made of concrete. By forming together with the floor slab 3, the convex portion 12 is integrally formed in advance. Further, a concave portion 13 into which the convex portion 12 is fitted is formed on the lower surface 4 a of the rail 4.

  As shown in FIG. 2, a large number of vertical reinforcing bars 14 and horizontal reinforcing bars 15 are arranged in the inside of the rail 4 along the longitudinal direction with a predetermined interval. For example, the height of the rail 4 is about 1000 mm. Taking the case of the above as an example, the vertical reinforcing bars 14 are arranged with an interval of around 120 mm. In the shear pin structure 10, one shear pin structure 10 is arranged, for example, at an interval of 1 m (every eight vertical reinforcing bars 14) in consideration of design strength when an automobile or the like collides. In the shear pin structure 10, contrary to FIG. 1, the convex portion 12 may be provided on the lower surface 4 a of the rail 4 and the concave portion 13 may be provided on the upper surface 3 a of the floor slab 3.

  As shown in FIG. 1, the vertical rebar 14 of the balustrade 4 arranged at the position of the shear pin structure 10 has a lower end up to a position spaced apart from the concave portion 13. The edges of the reinforcing bar 14 and the reinforcing bar 11 of the convex portion 12 in the floor slab 3 are cut.

  Further, as shown in FIG. 2, the vertical rebar 14 of the balustrade 4 disposed between the shear pin structure 10 and the shear pin structure 10 has a lower end of the vertical rebar 14 of the balustrade 4 as shown in FIG. Therefore, the vertical reinforcing bar 14 of the rail 4 and the reinforcing bar 11 'provided inside the floor slab 3 are also cut off at this portion. The vertical reinforcing bars 7 are provided corresponding to the positions where the vertical reinforcing bars 14 of the balustrade 4 are arranged.

  The rail 4 is formed by placing concrete on the floor slab 3 formed by projecting the vertical reinforcing bars 7 and the projecting portions 12 from the upper surface 3a of the floor slab 3 through a formwork (not shown). The floor slab 3 and the rail 4 and the ground cover 6 may be integrally formed, or the engaging groove into which the vertical reinforcing bar 7 protruding from the upper surface 3a of the floor slab 3 can be engaged, and the convex portion 12 is fitted. The balustrade 4 that has been previously made of precast concrete with a concave portion 13 to be mated, and the vertical rebar 7 is engaged with the engaging groove, and the concave portion 13 is fitted to the convex portion 12. After being installed on the plate 3, the rail 4 may be fixed integrally to the floor plate 3 via the vertical reinforcing bars 7 by placing concrete in the engaging groove.

  As described above, when concrete is placed on the floor slab 3 to form the rail 4, as shown in FIG. 1B, the convex portion 12 and the concave portion 13 are not fixed. It is preferable that the anti-adhesive material 16 such as a film is disposed on the outer peripheral surface of the film 12 so as to be easily separated.

  Next, the operation of the above embodiment will be described.

  As shown in FIGS. 1 to 3, the floor slab 3 and the balustrade 4 are integrally connected via a vertical reinforcing bar 7, and a convex portion 12 and a concave portion are provided between the floor slab 3 and the balustrade 4. The shear pin structure 10 which receives the force of a horizontal direction is provided by 13 being fitted to an up-down direction.

Accordingly, as shown in FIG. 1A, when a vehicle traveling on the floor slab 3 collides with the rail 4, a collision force F ₁ directed from the inside to the outside acts on the rail 4, but the collision By receiving the force F ₁ with the tensile strength of the vertical rebar 7 arranged at the inner position close to the inner surface of the rail 4 and receiving with the strength of the shear pin structure 10 that restrains the movement in the horizontal direction, the rail 4 is upright. Keep state. That is, the handrail 4 has a function of preventing the departure of the conventional vehicle.

On the other hand, when a tsunami is generated by a huge earthquake and the tsunami is pushed to the height of the upper structure 5 in FIG. 6A, a very large wave force F ₂ acts on the outer surface of the upper structure 5. become.

As shown in FIG. 1A and FIG. 3A, when a large wave force F ₂ acts on the outer surface of the upper structure 5, the concave portion 13 of the shear pin structure 10 is separated from the convex portion 12 by the overturning moment acting on the rail 4. Since the shear pin structure 10 cannot exhibit the binding force, the rail 4 and the floor slab 3 are only connected by the vertical reinforcing bar 7 arranged at a position close to the inner surface of the rail 4, The balustrade 4 bends around a bent fulcrum 20 in the vicinity of the boundary S in the vertical reinforcing bar 7, and collapses to the inner upper surface 3a of the floor slab 3, as shown in FIG.

On the other hand, one rail 4 collapses inward in the width direction of the floor slab 3 due to the action of the tsunami, but the width column 4 on the opposite side of the collapsed rail 4 sandwiches the floor slab 3 in the width direction. Wave force acts from the inside. The handrail 4 is designed so as not to cause a problem at the time of a vehicle collision from the inside, but the wave force F ₂ caused by the tsunami is larger than the collision force F ₁ at the time of the automobile collision, and therefore the wave force F applied from the inside. ₂ may cause the opposite rail 4 to collapse outward.

FIG. 6A shows an example of the vertical dimension of the upper structure 5. The height dimension H ₁ of the bridge girder 2 is 2000 mm, the height dimension H ₂ of the floor slab 3 is 320 mm, and the height dimension H of the column 4. ₃ is 1080 mm, so the height dimension H of the superstructure 5 is 3400 mm.

Accordingly, when the rail 4 having a height of 1080 mm collapses, the area of the upper structure 5 that receives the tsunami wave force F ₂ is reduced by only the height 4 and the load actually received by the upper structure 5 is reduced. The problem of the structure 5 being washed away by the tsunami can be reduced.

  Moreover, since the load which the upper structure 5 receives by the railing 4 collapsing becomes small, the fixing structure for fixing the upper structure 5 to the pier 1 can also be reduced.

  FIG. 4 (a) is a cut front view of the main part showing another embodiment of the bridge of the present invention. As shown in FIG. 4 (a), the longitudinal reinforcement 7 is provided between the rail 4 and the floor slab 3, and the inner side in the width direction of the floor slab 3 from above the rail 4 through the interior of the ground cover 6. An inclined reinforcing bar 8 extending obliquely downward in the interior is arranged. The vertical reinforcing bar 7 and the inclined reinforcing bar 8 have a menase hinge structure having a crossing point X at an inner position of the ground cover 6 which is the inner side in the width direction of the floor slab 3 in the rail 4 and at a position near the boundary S. The bending fulcrum 20 by 9 is formed. This menase hinge structure 9 is a general technique used in the field of building technology to aggregate deformations of buildings at intersections when reinforcing bars are placed.

In FIG. 4A, when a vehicle traveling on the floor slab 3 collides with the rail 4, a collision force F ₁ from the inside to the outside acts on the rail 4, but the vertical reinforcing bar in the above embodiment is used. in addition to the tensile strength by 7, along with receiving the collision force F ₁ by the tensile strength by the inclined reinforcing bar 8 can receive the impact force F ₁ by the strength of the shear pin structure 10 for restraining the movement in the horizontal direction.

On the other hand, in the configuration of FIG. 4A, when a very large wave force F ₂ acts on the outer surface of the upper structure 5 due to a tsunami or the like, the recess 13 of the shear pin structure 10 is caused by the overturning moment acting on the rail 4. Is pulled out from the convex portion 12, the shear pin structure 10 cannot exert a restraining force, and the rail 4 and the floor slab 3 are crossed at an intersection X near the inner surface of the rail 4 and near the boundary S. Since the vertical bar 7 and the inclined reinforcing bar 8 are only connected via the menase hinge structure 9, the balustrade 4 is bent around the bent fulcrum 20 of the menase hinge structure 9, as shown in FIG. Collapses to the inner upper surface 3a of the floor slab 3.

  FIG. 6B shows an embodiment in which a fairing is installed at an outer position in the width direction of the superstructure 5 in FIG. 6A. The fairing 17 includes a bridge girder 2, a floor slab 3, And a middle portion in the height direction protrudes outward.

  As described above, when the fairing 17 whose intermediate portion in the height direction protrudes to the outside is provided on the outside including the bridge girder 2 and the floor slab 3, the superstructure 5 receives the collapse of the rail 4 due to the tsunami as described above. In addition to the effect of reducing the load, the effect of reducing the load received by the upper structure 5 by rectifying the tsunami by the fairing 17 can be expected.

  The present inventors made a 1/50 model of the superstructure 5 shown in FIGS. 6 (a) and 6 (b), and installed this model in a water tank for creating a water current (wave of tsunami). A water tank experiment for measuring a drag per unit length in the traveling direction) was performed and a wave force analysis was performed. The result of the wave force analysis is shown in the graph of FIG.

  In FIG. 5A, in the case of the model of the superstructure 5 provided with the balustrade 4 on both the upstream side and the downstream side of the water flow as in the prior art, B is the balustrade 4 on both the upstream side and the downstream side of the water flow. In the case of the model of the superstructure 5 from which C is removed, C removes the rails 4 on both the upstream side and the downstream side of the water flow, and in the case of the model of the superstructure 5 in which the fairing 17 is further installed, D denotes the fairing 17 The model of the superstructure 5 is shown in which the installation is made, the rail 4 on the upstream side of the water flow is removed, and the rail 4 on the downstream side is left.

  As shown in FIG. 5, the upper structure 5 having the rails 4 on both the upstream side and the downstream side as in the conventional case of A shows a very high wave force, whereas the upstream structure of the water flow like B In the upper structure 5 in which both the rails 4 on the downstream side and the downstream side are collapsed, the wave force is reduced to about 2/3 of the conventional case of A. Further, in the upper structure 5 in which a fairing is installed as in C and the rails 4 on both the upstream side and the downstream side of the water flow are collapsed, the wave force is reduced to about ½ of the conventional case of A. . In addition, the fairing 17 is installed as in D, the upper column 4 on the upstream side of the water flow is removed, and the upper structure 5 that remains in the downstream column (remains without collapse) is also fair as in B. The wave force was reduced to the same extent as in the case of the upper structure 5 in which the ring 17 was not provided and both the upstream and downstream rails 4 of the water flow collapsed.

  As is clear from FIG. 5, the upper structure 5 having the rails 4 on both the upstream side and the downstream side of A in the prior art shows a very high wave force, whereas the upstream side of the water flow like B In the superstructure 5 in which both the rails 4 on the downstream side and the downstream side have collapsed, the wave force is reduced to about 2/3 of the conventional case of A, and a fairing is installed as in C, and further upstream of the water flow In the upper structure 5 in which both the rails 4 on the side and the downstream side collapsed, the wave force was reduced to about ½ of the conventional case of A.

  In the water tank experiment, the same result as that obtained by the analysis test was obtained.

  In the above embodiment, the case where the rail 4 collapses at the boundary portion S between the rail 4 and the floor slab 3 has been described. However, the rail 6 up to the height of the ground cover 6 and the ground cover 6 is the floor plate 3. It may be formed integrally so that the balustrade 4 above the ground cover 6 has the same configuration as in the above embodiment and collapses.

  Note that the bridge of the present invention is not limited to the above-described embodiments, and it is needless to say that various changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Bridge pier 2 Bridge girder 3 Floor slab 3a Upper surface 4 Hand rail 4a Lower surface 5 Upper structure 6 Ground cover 7 Vertical reinforcement 8 Inclined reinforcement 9 Menase hinge structure 10 Shear pin structure 12 Convex part 13 Concave part 17 Fairing 20 Bending fulcrum S Boundary part

Claims (5)

A bridge comprising an upper structure having a bridge girder on the pier, a floor slab provided on the bridge girder, and a rail provided along the longitudinal direction of the floor slab on the upper side in the width direction of the floor slab. There,
Between the upper surface of the floor slab and the lower surface of the railing has a shear pin structure that receives a horizontal force by fitting each other vertically.
When a wave force acts on the balustrade from the outside in the width direction by providing a vertical reinforcing bar arranged extending vertically between the inside of the balustrade and the inside of the floor slab at the inner side in the width direction than the shear pin structure Further, the bridge has a bent fulcrum that bends with the longitudinal rebar as a fulcrum in the vicinity of the boundary between the rail and the floor slab.   The bent fulcrum is slanted from the inside of the railing to the inside of the floor slab and vertically extending from the inside of the railing to the inside of the floor slab. 2. The bridge according to claim 1, wherein the inclined reinforcing bar extending in a manner has a menase hinge structure that crosses in the vicinity of a boundary between the railing and the floor slab.   The bridge according to claim 1 or 2, wherein the handrail has a configuration including a ground cover.   In the shear pin structure, the floor slab and the reinforcing bar provided in the rail are protruded from one of the upper surface of the floor slab and the lower surface of the rail, and the protruding portion of the reinforcing bar is formed of concrete, and the floor The bridge according to any one of claims 1 to 3, further comprising a concave portion formed so as to be fitted to the convex portion on the other of the upper surface of the plate and the lower surface of the rail.   2. A fairing having a height including the bridge girder and the floor slab and having a shape in which a middle portion in the height direction protrudes outward is provided at a width direction outer side position of the upper structure. 4. The bridge according to any one of 4.

Images