JP2019039269A - Aseismatic reinforcement method and aseismatic reinforcement structure - Google Patents

Abstract

To provide an aseismatic reinforcement technology which facilitates the installation even when there is any factor typical to the existing bridge.SOLUTION: Four bridge girders G1 to G4 are integrated together into one connection girder GX. The constraint in the horizontal direction is reduced with respect to supports B2, B3, B4, B5, B6, and B7 installed in bridge piers P1 to P3. For bridge abutment A1, A2 other than the bridge piers P1 to P3 (the bridge piers which support the supports B2, B3, B4, B5, B6, and B7 to be reduced the constraint in the horizontal direction), the aseismatic reinforcement is applied. More specifically, the aseismatic reinforcement is not given to the bridge piers P1 to P3 for which the construction condition is severe, and the aseismatic reinforcement is given to the bridge abutment A1, A2 for which the construction condition is mild.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a seismic reinforcement technique for a bridge, and more particularly to a seismic reinforcement technique for a bridge having a difficult-to-construct part at a lower part of the bridge.

  Based on recent large-scale earthquake damage, the seismic design standards have been reviewed. On the other hand, many existing bridges are designed according to old seismic design standards. Therefore, seismic reinforcement work will be performed on the existing bridge.

  Specifically, the earthquake resistance of a bridge pier or a pier foundation is improved (for example, patent document 1). Various construction machines and materials are required for seismic reinforcement work.

JP-A-2015-203291

  However, there are many railways, roads and rivers under the bridge. In such places, it is difficult to install construction machines and carry in materials. In addition, more careful safety measures are required when railroads and roads are adjacent to each other. Temporary deadlines are required for the construction of piers in rivers.

  Furthermore, when reinforcing a structure close to a railway, it may be possible to construct only in a time zone where the train does not travel at night from the viewpoint of safety. When reinforcing a structure close to a road, there are restrictions such as partially restricting the lane or performing construction with closed roads. Further, the above-mentioned reinforcement requires discussion with the railway operator, road manager, and river management, and there is a problem that not only the construction cost increases but also the construction period cannot be foreseen.

  Such factors peculiar to existing bridges contribute to delaying the earthquake resistance of existing bridges.

  This invention solves the said subject, and it aims at providing the earthquake-proof reinforcement method and earthquake-proof reinforcement structure which can be easily constructed even when there exists a factor peculiar to an existing bridge.

  The present invention that solves the above-mentioned problems is a method for seismic reinforcement of a bridge having N (N is an integer of 2 or more) bridge girder. The step of connecting consecutive K (K is an integer of 2 or more and N or less) consecutive bridge girder among the N consecutive bridge girders and connecting girder and installed on at least one pier or abutment supporting the connecting girder A step of reducing horizontal restraint of the bearing, and a step of reinforcing at least one pier or abutment other than the pier or the abutment supporting the bearing with the reduced horizontal restraint.

  By connecting K-girder individual girder, individual girder can be prevented from being dropped. In addition, by reducing the horizontal restraint of the bearing, the horizontal inertia force (hereinafter referred to as “horizontal force”) acting on the girder is reduced and transmitted to the abutment or pier. On the other hand, in the bearing part that does not reduce the horizontal restraint of the bearing, the horizontal force that should be transmitted in the bearing part that originally reduced the horizontal restraint is also transmitted to the abutment or the pier, and the horizontal force is transmitted. Reinforce seismic reinforcement at the abutments and piers. The support for reducing the horizontal restraint can be appropriately selected according to the strength of the piers and abutments and the difficulty level of reinforcement as in the examples described later. It becomes possible to reinforce at an easy construction site. That is, even if there are factors peculiar to existing bridges, reinforcement can be easily performed.

  In the present specification, “horizontal” means a direction parallel to a plane including the bridge axis direction of the bridge and the direction perpendicular to the bridge axis.

  Preferably, in the above invention, the bridge girder is connected so as to oppose a tensile force and oppose a compressive force.

  Thereby, in a connection girder, the bending moment in a horizontal surface is transmitted to adjacent bridge beams.

  Preferably, in the above invention, the bridge girder is connected to oppose the tensile force by fixing a cable, a steel material or the like to both ends of the connection girder.

  When an external force is applied so that the bridge girders are pulled together, the cable resists the force in the pulling direction.

  The present invention for solving the above problems is a bridge having N (N is an integer of 2 or more) bridge girder. It is installed on a connecting girder that connects consecutive K (K is an integer not less than 2 and not more than N) bridge girders among the N girder bridge girder and at least one pier or abutment that supports the connecting girder. At least one abutment or abutment other than the abutment or abutment that has a bearing with reduced direction restraint and supports the bearing with reduced horizontal restraint is seismically reinforced.

  Preferably in the above invention, the connecting means has a tensile force resistance function and a compression force resistance function.

  Preferably, in the above invention, the tensile force resistance function is a cable fixed to both ends of the connecting beam.

  According to the seismic strengthening method and the seismic strengthening structure according to the present invention, construction can be easily performed even when there are factors peculiar to existing bridges.

Existing bridge example Application examples Earthquake behavior in application examples Modification 1 Modification 2 Modification 3 Modification 4 Modification 5 Connection means example 1 Example 2 of connecting means Connection means example 3 (side view) Connection means example 3 (plan view)

~ Examples of existing bridges ~
FIG. 1 is an example of an existing bridge to which the present invention is applied. Seismic reinforcement of multi-span bridges.

  In FIG. 1, it is a four span bridge with continuous simple girders. It consists of bridge girders G1-G4.

  One end of the bridge girder G1 is supported by the pier A1 via the support B1, and the other end of the bridge girder G1 is supported by the pier P1 via the support B2. One end of the bridge girder G2 is supported by the pier P1 via the support B3, and the other end of the bridge girder G2 is supported by the pier P2 via the support B4. One end of the bridge girder G3 is supported by the pier P2 via the support B5, and the other end of the bridge girder G3 is supported by the pier P3 via the support B6. One end of the bridge girder G4 is supported by the pier P3 via the support B7, and the other end of the bridge girder G4 is supported by the abutment A2 via the support B8.

  In the supports B1 to B8, the horizontal displacement is restricted. Therefore, when a horizontal force is generated in the bridge girders G1 to G4 at the time of the earthquake, they are transmitted to the abutments A1 and A2 and the piers P1 to P via the supports B1 to B8. Seismic reinforcement against this is necessary.

  By the way, it is assumed that the pier P3 is provided in the river and that a railroad and a road are running in parallel with the river. The pier P1 and the pier P2 are adjacent to the railway. The pier P2 is adjacent to the road.

  Therefore, since the construction conditions are severe, large-scale seismic reinforcement for the piers P1 to P3 is difficult. In the vicinity of the abutments A1 and A2, the restrictions on the construction conditions are loose. For example, a sufficient work space for reinforcement work can be secured.

-Application example of the present invention-
FIG. 2 shows an application example of the present invention. The existing multi-span bridge shown in FIG. 1 is subjected to seismic reinforcement under the above construction conditions (factors specific to the existing bridge).

  First, the bridge beam G1 and the bridge beam G2 are connected, the bridge beam G2 and the bridge beam G3 are connected, the bridge beam G3 and the bridge beam G4 are connected, and the four bridge beams G1 to G4 are integrated into one connection beam GX.

  In the connecting girder GX, the bending moment in the horizontal plane is transmitted to adjacent bridge girders (the details of the connection will be described later).

  Between the digits in FIG. 2, dotted squares indicate the connecting portions J1 to J3.

  Next, among the piers P1 to P3 and the abutments A1 and A2 that support the connecting girder GX, the horizontal restraint is reduced for the supports B2, B3, B4, B5, B6, and B7 installed on the piers P1 to P3 ( Details of horizontal constraint reduction will be described later). The bearings B2, B3, B4, B5, B6, and B7 continue to transmit the weight of the connecting girder to the piers P1 to P3. In addition, the supports B1 and B8 installed on the abutments A1 and A2 are left as they are (not subject to horizontal restriction reduction).

  In the support shown in FIG. 2, the solid-line solid triangle indicates that the horizontal direction is not reduced (the horizontal movement is still restricted), and the dotted-lined triangle indicates the horizontal direction reduction.

  On the other hand, of the piers P1 to P3 and the abutments A1 and A2 that support the connecting girder GX, except for the piers P1 to P3 (the piers that support the supports B2, B3, B4, B5, B6, and B7 that are subject to horizontal constraint reduction) The abutments A1 and A2 will be seismically strengthened.

  In other words, in the piers P1 to P3 where the construction conditions are severe, seismic reinforcement is not performed (or relatively light seismic reinforcement is performed), and seismic reinforcement is performed on the abutments A1 and A2 where the construction conditions are loose (details of seismic reinforcement) Will be described later).

  In the piers and abutments in FIG. 2, hatching indicates a seismic reinforcement target, and intermediate coating indicates a non-seismic reinforcement target.

~ Behavior during earthquake ~
FIG. 3 is a schematic diagram (plan view) showing the behavior during an earthquake in the application example. However, for convenience of explanation, the displacement amplitude is shown in an emphasized manner.

  In the connecting beam GX, the bending moment in the horizontal plane is transmitted to adjacent bridge beams. On the other hand, horizontal restraint is reduced in the supports B2, B3, B4, B5, B6, and B7 installed on the piers P1 to P3 (see FIG. 2).

  When a horizontal force (inertial force of the connecting girder) is generated in the connecting beam GX during the earthquake, the horizontal force is concentrated on the abutments A1 and A2. On the other hand, transmission of horizontal force to the piers P1 to P3 is reduced.

  The abutments A1 and A2 have sufficient seismic reinforcement and can withstand horizontal force. The bridge piers P1 to P3 are not seismically reinforced, but the transmitted horizontal force is reduced, and the existing seismic force can withstand the horizontal force.

~effect~
Even when there are factors peculiar to existing bridges that cause differences in construction conditions depending on the location of the multi-span bridge, it is possible to easily perform construction at easy construction sites while avoiding difficult construction sites.

  Damage can be prevented even with the abutments A1 and A2 that have undergone sufficient seismic reinforcement and the piers P1 to P3 that have not undergone seismic reinforcement.

  By using the concatenated digits GX, the span of the concatenated digits becomes larger than each individual digit before the concatenation. For this reason, the natural period of a connection digit becomes longer than the natural period of each individual digit, and input seismic motion can be reduced.

~ Modification ~
In the above application example, the piers P1 to P3 were not subjected to seismic reinforcement (or relatively light seismic reinforcement), and were subjected to seismic reinforcement at the abutments A1 and A2.

  The present invention is not limited to the above application examples, and various modifications are possible. 4-8, it shows about the modifications 1-5. Between the illustrated digits, dotted squares indicate connecting means. In the illustrated bearing, the solid-line middle-coated triangle indicates that the horizontal direction restriction is not reduced (the horizontal movement is still restricted), and the dotted-lined triangle indicates the horizontal direction restriction reduction target. In the illustrated piers and abutments, hatching indicates a target for seismic reinforcement, and intermediate coating indicates a target for seismic reinforcement.

  FIG. 4 shows a first modification. It is a 5-span bridge with simple girder. The bridge girders G1 to G5 are defined as one connecting girder GX.

  Among the bridge piers P1 to P4 and the abutments A1 and A2 that support the connecting girder GX, horizontal restraint is reduced for the supports B1, B4, B5, B6, B7, B8, and B9 installed on the abutments A1 and P2 to P4. To do.

  On the other hand, among the piers P1 to P4 and the abutments A1 and A2 that support the connecting girder GX, seismic reinforcement is performed on the pier P1 and the abutment A2 other than the abutments A1 and the piers P2 to P4.

  That is, a part of the pier may be a seismic reinforcement target.

  FIG. 5 is a second modification. It is a 5-span bridge with simple girder. The bridge girders G1 to G5 are defined as one connecting girder GX. And

  Of the piers P1 to P4 and the abutments A1 and A2 that support the connecting girder GX, the horizontal restraint is reduced for the supports B1, B4, B5, B6, B7, and B10 installed on the abutments A1 and A2 and the piers P2 and P3. To do.

  On the other hand, among the piers P1 to P4 and the abutments A1 and A2 that support the connecting girder GX, seismic reinforcement is performed on the piers P1 and P4 other than the abutments A1 and A2 and the piers P2 and P3.

  That is, it is good also considering a seismic reinforcement object other than an abutment.

  FIG. 6 shows a third modification. This is a 4-span bridge with simple girder. The bridge girders G1 and G2 are connected to the connecting beam GX1 through the connecting portion J1, and the bridge beams G3 and G4 are connected to the connecting beam GX2 through the connecting portion J2.

  Of the abutments A1 and piers P1 and P2 that support the connecting beam GX1, horizontal restraint is reduced for the supports B2 and B3 installed on the pier P1. Of the bridge piers P2 and P3 and the abutment A2 that support the connecting girder GX2, horizontal restraint is reduced for the supports B6 and B7 installed on the pier P3.

  On the other hand, among the abutment A1 and the piers P1 and P2 that support the connecting girder GX1, seismic reinforcement is performed on the abutment A1 and the pier P2 other than the pier P2. Of the piers P2, P3 and abutment A2 that support the connecting girder GX2, seismic reinforcement is performed at the pier P2 and the abutment A2 other than the pier P3.

  In other words, not all bridge girders need to be one connected girder. In the example shown in the figure, four bridge girders are connected to two double girders.

  FIG. 7 shows a fourth modification. It is a three-span Gerber bridge. Hinges H1 and H2 exist between the piers P1 and P2. The hinges H1 and H2 are connected to each other, and the bridge beams G1 to G3 are set as one connection beam GX.

  Of the piers P1 and P2 and the abutments A1 and A2 that support the connecting girder GX, horizontal restraint is reduced for the supports B2 and B3 installed on the piers P1 and P2.

  On the other hand, among the piers P1 and P2 and the abutments A1 and A2 that support the connecting girder GX, the seismic reinforcement is performed on the abutments A1 and A2 other than the piers P1 and P2.

  That is, the present invention can be applied to a Gerber bridge other than a continuous simple girder.

  FIG. 8 shows a fifth modification. It is a three-span Gerber bridge. A hinge H1 exists between the abutment A1 and the pier P1, and a hinge H2 exists between the pier P2 and the abutment A2. The hinges H1 and H2 are connected to each other, and the bridge beams G1 to G3 are set as one connection beam GX.

  Of the piers P1 and P2 and the abutments A1 and A2 that support the connecting girder GX, horizontal restraint is reduced for the supports B2 and B4 installed on the pier P1 and the abutment A2.

  On the other hand, among the piers P1 and P2 and the abutments A1 and A2 that support the connecting girder GX, the seismic reinforcement is performed on the abutments A1 and the pier P2 other than the pier P1 and the abutment A2.

  That is, various modifications are possible in the Gerber bridge.

  Furthermore, it is not limited to the said modifications 1-5, For example, it can apply also to the multi span bridge which consists of a simple girder and a continuous girder.

~ Consolidation details ~
The connecting girder GX has a tensile force resistance function 11 and a compressive force resistance function 12 in the connecting portions (J1 to J4) of the individual bridge beams. When a horizontal force acts on the connecting girder during an earthquake and a tensile force acts between the bridge girders on the connecting portion, the tensile force counter-function 11 counters the force in the tensile direction. Similarly, when a compressive force is applied from the bridge beams, the compressive force counter function 12 counters the force in the compression direction.

  For example, in the example of FIG. 3 (plan view), an inertial force at the time of earthquake acts downward in the figure, a tensile force acts on the lower side of the illustrated connecting girder, and the tensile force counter function 11 counteracts, on the upper side in the figure. A force in the compression direction acts, and the compression force counter function 12 counters. As a result, in the connecting beam GX, the bending moment in the horizontal plane is transmitted to adjacent bridge beams.

  In the example of FIG. 3, horizontal force is generated in one direction for convenience, but horizontal force is generated in both directions during an earthquake. When a horizontal force is generated in the direction opposite to the example of FIG. 3, the compressing force counter function 12 counters on the lower side in the figure, and the tensile force counter function 11 counters on the upper side in the figure.

  The specific connecting means is not limited to a specific structure, and various modifications are possible.

  FIG. 9 shows a connection example 1.

  Between each bridge girder, the PC steel bar 21 is arranged along the side surface of the bridge girder, and the PC steel bar is fixed to the bracket 22 provided on the bridge girder, whereby the tensile force resistance function 11 is formed.

  Instead of the PC steel bar, a PC cable, a reinforcing bar or other steel material may be used.

  Between each bridge girder, the interstitial concrete 23 is laid, and the compressive force resistance function 12 is formed. The interstitial concrete may have a slit so as to cope with displacement in the bridge axis direction due to temperature change.

  Filled concrete need not be placed on the entire cross section between each bridge girder. That is, if it is at both ends, it does not need to be in the center. For example, in FIG. 12, it may be installed only in the illustrated upper end portion and the illustrated lower end portion of the connecting portion of the bridge girders G1 and G2, and may not be installed in the intermediate portion.

  Instead of concrete, mortar, cement paste, steel, resin or rubber may be used.

  FIG. 10 is a connection example 2.

  Between each bridge girder, the steel pipe 20 is arranged along the side face of the bridge girder, and the steel pipe is fixed to the bracket 25 provided on the bridge girder, whereby the tensile force resistance function 11 is formed.

  On the other hand, the concrete 26 is filled in the steel pipe, and the compressive force resistance function 12 is formed.

  The steel pipe 20 filled with the concrete 26 may be provided at an efficient position so that the connecting beam resists the bending moment in the horizontal plane. It does not need to be provided on the inner surface of the beam and may be provided on the outer surface.

  11 and 12 show a connection example 3. FIG. 11 is a side view, and FIG. 12 is a plan view.

  Whereas the tensile force resistance function 11 of the connection example 1 is to dispose a PC steel rod between each bridge girder, the tensile force resistance function 11 of the connection example 3 is the both ends of the connection beam GX (the illustrated bridge beam G1 and the bridge beam G5). The cable 27 is fixed to the cable 27, and tension is introduced into the cable 27. The tension of the cable 27 is transmitted to the bridge girders G <b> 1 to G <b> 5 through the fixing unit 28 and the deflecting unit (deviator) 29. The cable and fixing unit are made of steel, resin, or the like.

  The cable 27 can reduce the horizontal displacement of each bridge girder G1-5.

  On the other hand, in the same manner as in the connection example 1, the interstitial concrete 23 is placed between the bridge girders, and the compressive force resistance function 12 is formed.

  Furthermore, it is not limited to the said connection examples 1-3, For example, if it is a steel girder, you may connect between each bridge girder via an attachment board.

~ Horizontal restraint reduction means ~
In FIG. 1, the horizontal displacement is restrained for the supports B1 to 8 in the existing bridge. In FIG. 2, the horizontal restraint is reduced for the supports B2, B3, B4, B5, B6, and B7.

  Specifically, replace existing bearings with seismic isolation bearings and sliding bearings.

  If it is a seismic isolation bearing, the transmission of the horizontal force of the bridge girder to the piers P1 to P3 can be greatly reduced.

  If it is a sliding bearing, if the friction coefficient of the sliding bearing is μ and the vertical force that the bearing bears is V, the horizontal force acting on the bearing from the bridge girder exceeds μV, and the horizontal force exceeding the sliding μN is It can be prevented from being transmitted to the piers P1 to P3.

  In this case, the bridge piers P1 to P3 are large if the cross-sectional force generated at the pier when the μN is loaded at the support positions of the existing piers P1 to P3 is less than the strength of the pier (for example, bending strength, shear strength, etc.). Does not damage the scale.

  Usually, it is difficult to adjust the value of N significantly, and the friction coefficient of the bearing to be replaced is appropriately selected according to the strength of the pier or abutment that is difficult to reinforce.

  In the side view of FIG. 1 and the like, the bridge girder end portion seems to be supported by one support, but in reality, the bridge girder has a depth in a direction orthogonal to the drawing and a plurality of supports are arranged (for example, FIG. 9). reference). When reducing horizontal restraints, replace all bearings.

~ Seismic reinforcement means ~
In the application example, the existing bridge in FIG. 1 is subjected to seismic reinforcement at the abutments A1 and A2 as shown in FIG. In Modification 1 (FIG. 4), Modification 2 (FIG. 5), Modification 3 (FIG. 6), and Modification 5 (FIG. 8), seismic reinforcement is performed on the pier.

  As an example of seismic reinforcement of a bridge pier, RC bending, steel sheet winding, resin sheet winding, etc. increase the bending or shear strength and toughness of a column, or increase piles.

  As an example of the seismic reinforcement of the abutment, in addition to the method used in the pier, the ground anchor increases the unity between the abutment and the rear portion.

In addition, since the bearings installed on the piers and abutments to be reinforced will bear an increased horizontal force during earthquakes compared to the initial design, the bearing body and anchor bolts can be replaced, or the concrete for anchoring can be increased. Reinforcement such as increasing the number of anchor bolts.

A1, A2 Abutment P1-P4 Pier G1-G5 Bridge girder GX, GX1, GX2 Connecting girder B1-B10 Bearing J1-J4 Connecting part H1-H4 Hinge 11 Tensile force resistance function 12 Compressive force resistance function 20 Steel pipe 21 PC steel rod 22 Bracket 23 Filled concrete 25 Bracket 26 Filled concrete 27 Cable 28 Fixing part 29 Deviator

Claims (6)

A method of seismic reinforcement of a bridge having N (N is an integer of 2 or more) bridges,
A step of connecting consecutive K (K is an integer of 2 or more and N or less) consecutive bridge beams among the N bridge beams to form a connection beam;
Reducing the horizontal restraint of a bearing installed on at least one pier or abutment that supports the connecting girder;
Reinforcing at least one abutment or abutment other than the abutment or abutment that supports the bearing with reduced horizontal restraint;
Seismic reinforcement method consisting of The seismic reinforcement method according to claim 1, wherein the bridge girder is connected so as to oppose a tensile force and oppose a compressive force. The seismic reinforcement method according to claim 2, wherein the connection of the bridge girders against the tensile force is performed by fixing cables to both ends of the connection girders. A bridge having N (N is an integer of 2 or more) bridge girder,
A connecting girder in which consecutive K (K is an integer of 2 or more and N or less) consecutive bridge girder among the N girder bridge girder,
Installed on at least one pier or abutment that supports the connecting girder and having a reduced horizontal restraint;
A bridge in which at least one abutment or abutment that supports the bearing with reduced horizontal restraint is seismically reinforced. The bridge according to claim 4, wherein the connecting means has a tensile force resistance function and a compression force resistance function. The bridge according to claim 5, wherein the tensile force resistance function is a cable fixed to both ends of the connecting beam.