JP5330118B2 - Main girder connection structure - Google Patents

Description

  The present invention relates to a main girder connecting structure for connecting main girders adjacent in the bridge axis direction at their intermediate fulcrum.

  In general, a simple girder bridge has a configuration in which expansion joints are arranged between main girder adjacent to each other in the bridge axis direction. Moreover, in the connection girder bridge, the main girder constructed as a simple girder is connected in the bridge axis direction by the reinforced concrete structure at the intermediate fulcrum, thereby constituting a continuous girder.

  In “Patent Document 1”, as a main girder connecting structure in a connecting girder bridge, there is a configuration in which a PC cable penetrating in the bridge axis direction is placed on cast-in-place concrete that is driven between the two main girder. Have been described.

  On the other hand, for existing bridges, a no-joint method for connecting main girders adjacent in the direction of the bridge axis with their floor slabs is known.

  As a no-joint construction method for this existing floor slab, in “Patent Document 2”, the upper surface portion of the end portion on the intermediate fulcrum side of each main girder is formed as a stepped-down portion displaced downward from the floor slab upper surface by a predetermined amount. Above, there is described a floor slab connecting method in which connecting members are arranged so as to straddle the gap between the two main girders, and both ends in the bridge axis direction are fixed to the stepped portions of the main girders, respectively. Yes. Further, in “Patent Document 3”, a thin ECC (that is, a plurality of microcracked fiber reinforced mortar) connecting plates is used as the connecting member, and both ends in the bridge axis direction are connected to the bottom surface of the stepped portion of each main girder by pin connection. An ultra joint construction method is described which is fixed to the structure.

JP 2009-41271 A JP 2007-309032 A JP 2008-190130 A

  In the connecting girder bridge, the expansion joints arranged in the simple girder bridge are not required, so that the traveling performance of the vehicle on the bridge surface can be improved and the vibration noise can be reduced.

  However, in connection girder bridges, the main girder connection structure is configured as a reinforced concrete structure that is integrally constructed in a form that includes the horizontal girder, so that the construction including the reinforcement is complicated. There's a problem. In addition, there is a problem that such a main girder connection structure cannot be replaced in the future.

  On the other hand, the no-joint method for existing floor slabs has the following problems.

  In other words, the no-joint method using the floor slab connection method is intended to repair and reinforce existing bridges, so application to new bridges has problems in terms of durability, and applicable cross-sectional forces are also limited. is there. Moreover, the design of new bridges is difficult because of the effects of creep and drying shrinkage, so no-joint construction using the floor slab connection method has been applied only to existing bridges. Not applied.

  In addition, in the no-joint method using the ultra joint method, a thin ECC connecting plate functions as a substitute for the telescopic device, and the fixing to each main girder at both ends of the bridge axis direction is fixed to the main girder. Since it is performed by pin coupling to the bottom surface of the stepped-down portion, there is a problem in terms of durability. Moreover, it is extremely difficult to make this ECC connecting plate function as a stress transmission member between both main beams.

  The present invention was made in view of such circumstances, and as a main girder connection structure for connecting main girders adjacent in the bridge axis direction at their intermediate fulcrum, the required durability was secured. Thus, it is intended to provide a main girder connecting structure that can reduce the cross-sectional force generated in the connecting member in accordance with the deformation of the main girder and can transmit stress between both main girder. is there.

  The present invention is intended to achieve the above object by devising the structure of a connecting member that connects a pair of main girders.

That is, the main girder connection structure according to the present invention is
A main girder connecting structure for connecting a pair of main girders adjacent in the direction of the bridge axis at the intermediate fulcrum,
The upper surface portion of the end portion on the intermediate fulcrum side in each of the pair of main girders is formed as a stepped-down portion displaced downward by a predetermined amount from the upper surface of the floor slab of the main girder,
In a state in which the connecting member that connects the pair of main girders so as to transmit stress is arranged so as to straddle the gap between the two main girders, the steps of the main girders at both ends in the bridge axis direction of the connecting members It is configured as a connected floor slab that is fixed to the lower part,
The upper surface of the connection floor slab is formed so as to extend substantially flush with the upper surface of the floor slab, and the lower surface of the connection floor slab is above the intermediate portion in the bridge axis direction than both ends in the bridge axis direction on the lower surface. It is formed so as to be displaced to the side.

  The “main girder connection structure” according to the present invention can be applied to a new bridge, and can also be applied when an existing floor slab is made into a no-joint.

  The “connected floor slab” is formed so that its upper surface extends substantially flush with the upper surface of the floor slab, and its lower surface displaces the intermediate portion in the bridge axis direction upward rather than both ends in the bridge axis direction. If it is formed, the specific shape is not particularly limited.

  As shown in the above configuration, in the main girder connecting structure according to the present invention, the upper surface portion of the end portion on the intermediate fulcrum side of each of the pair of main girders adjacent in the bridge axis direction is lower than the floor slab upper surface by a predetermined amount. The connecting members that connect the pair of main girders are arranged so as to straddle the gaps between the two main girders. It is configured as a connected floor slab fixed to the stepped part of the main girder, and this connected floor slab is formed so that its upper surface extends substantially flush with the floor slab upper surface, and its lower surface is a bridge. Since it is formed so that the bridge axial direction intermediate portion is displaced upward from the axial end portions, the following operational effects can be obtained.

  In other words, since the member thickness of the connecting floor slab is relatively thin at the intermediate portion in the bridge axis direction, it is easy to adjust the rigidity appropriately while ensuring the necessary minimum thickness as the floor slab. It becomes possible. Thus, both main girders can be softly connected at the intermediate fulcrum.

  Therefore, it is possible to reduce the cross-sectional force generated in the connecting floor slab as the connecting member in accordance with the deformation of the main girder, and to make this connecting floor slab function as a stress transmission member between both main girders.

  As described above, according to the present invention, as the main girder connecting structure for connecting the main girders adjacent in the bridge axis direction at the intermediate fulcrum, the required girder is secured and the main girder is deformed. The cross-sectional force generated in the connecting member can be reduced, and stress transmission between both main girders can be achieved.

  And according to this invention, compared with the conventional main girder connection structure, simplification of construction can be achieved. Further, it is possible to easily replace the main girder connection structure in the future as compared with the conventional main girder connection structure.

  In the above configuration, if the connecting floor slab is made of a low elastic cement-based material in which reinforcing bars are arranged, it is possible to suppress the rigidity lower than when it is made of reinforced concrete and increase its toughness. Become. This makes it easier to softly connect the main girders with the connecting floor slab.

  Here, the “low-elastic cement-based material” means a cement-based material having lower elasticity than the material constituting the main girder to be connected by the connecting floor slab, and its specific composition is particularly limited. Is not to be done. At this time, it is preferable to use a material having an elastic coefficient of 4/5 or less as the “low-elastic cement material” with respect to the elastic coefficient of the material constituting the main beam. It is more preferable to use a material having a coefficient.

  In the above configuration, as the shape of the lower surface of the connection floor slab, if the bridge axis direction intermediate portion on the lower surface is gradually displaced upward from the both ends of the bridge axis direction toward the center position in the bridge axis direction, It is possible to more effectively reduce the cross-sectional force generated in the coupled floor slab due to the deformation of the main girder, and it is possible to more smoothly transfer the stress between the two main girders. The improvement in performance can be achieved more effectively.

  In the above-described configuration, the both ends of the bridge deck direction in the connecting floor slab are fixed to the stepped portion of each main girder so as to protrude upward from the bottom surface of the stepped portion at a predetermined interval in the bridge axis direction. Via a plurality of anchor bolts or reinforcing bars and a plurality of reinforcing bars that are arranged at predetermined intervals in the direction orthogonal to the bridge axis so as to protrude from the end face in the bridge axis direction of the stepped-down portion. With this configuration, stress transmission between both main girders can be performed more smoothly. Moreover, at that time, the bending generated in the coupled floor slab with the deformation of one main girder can be efficiently transmitted to the other main girder as a couple.

  In the above configuration, it is also possible to configure the connection floor slab with cast-in-place material, but as this connection floor slab, a precast member arranged so as to straddle the gap, and both end surfaces in the bridge axial direction of this precast member It is also possible to employ a structure comprising cast-in-place concrete cast between the stepped portion of each main girder and the end face in the bridge axis direction. When the latter configuration is adopted, simplification of the construction of the main girder connection structure can be further promoted.

Side sectional view which shows the main girder connection structure which concerns on one Embodiment of this invention. Detailed view of part II in Fig. 1 Sectional view taken along line III-III in FIG. IV-IV sectional view of FIG. The same figure as FIG. 1 which shows the effect | action of the said embodiment. The same figure as FIG. 1 which shows the 1st modification of the said embodiment. The same figure as FIG. 1 which shows the 2nd modification of the said embodiment. Detailed view of part VIII in FIG. IX-IX sectional view of FIG.

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

  FIG. 1 is a side sectional view showing a main girder connecting structure 10 according to an embodiment of the present invention.

  As shown in the figure, the main girder connecting structure 10 according to the present embodiment has the main girder 12 and 14 of simple girder bridges adjacent to each other in the bridge axis direction on the bridge pier 16 positioned at the intermediate fulcrum. It is the structure connected to.

  Each of the pair of main girders 12 and 14 is configured as a precast girder made of prestressed concrete, and is supported on the upper end surface of the pier 16 via the support 22 at the bridge axial direction end on the pier 16 side. ing. In the present embodiment, the pair of main girders 12 and 14 are symmetric with respect to the bridge axis orthogonal plane at the intermediate fulcrum.

  The gap 20 between the pair of main girders 12 and 14 is set to a value of about 200 mm. Further, each of the main girders 12 and 14 has a hollow structure in the intermediate portion in the bridge axis direction, but both ends in the bridge axis direction have a solid structure.

  Each of the main girders 12 and 14 is formed as stepped portions 12b and 14b in which the upper surface portion of the end portion on the side of the pier 16 is displaced downward by a predetermined amount from the floor slab upper surfaces 12a and 14a of the main girders 12 and 14. ing. At that time, the bottom portions of the stepped portions 12b and 14b are formed at positions below the floor slab upper surfaces 12a and 14a by about 220 mm, and the end surfaces in the bridge axis direction are the bridge shafts of the main girders 12 and 14, respectively. It is formed at a position about 1200 mm away from the direction end face.

  In the main girder connecting structure 10 according to the present embodiment, a connecting member that connects the pair of main girders 12 and 14 is configured as a connecting floor slab 50.

  The connecting floor slab 50 is disposed so as to straddle the gap 20 between the two main girders 12 and 14, and the stepped portions 12 b and 14 b of the main girders 12 and 14 are respectively provided at both ends in the bridge axis direction. It is fixed. The connecting floor slab 50 is made of a low-elastic cement material in which a plurality of reinforcing bars 52, 54, 56, and 58 are arranged.

  At this time, as the low-elasticity cement-based material, Portland cement, limestone fine powder, expansion material, particle-adjusted natural sand, water-reducing agent, shrinkage-reducing agent, short fiber, etc. are used with an appropriate water binder ratio (for example, The mixture is mixed at a water binder ratio of about 48% and kneaded in a mixer. And by using such a low elastic cement type material, the elastic modulus is reduced by about 30% compared with the case where normal concrete is used.

  Further, this low elastic cement-based material has high toughness and crack dispersibility by using short fibers. In this case, for example, high-strength vinylon fibers having a fiber length of about 12 mm can be selected as the short fibers and mixed at an appropriate volume ratio (for example, a volume ratio of about 2%).

  Further, when a lower elastic modulus is obtained as the low-elastic cement material, it is possible to use a special lightweight aggregate that has been subjected to particle size adjustment or the like instead of natural sand.

  FIG. 2 is a detailed view of part II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  As shown in these drawings, the connecting floor slab 50 is formed so that the upper surface 50a thereof is substantially flush with the floor slab upper surfaces 12a and 14a of the main girders 12 and 14, and the lower surface 50b is formed. The bridge axis direction intermediate part 50bB is formed to be displaced upward from the bridge axis direction both end parts 50bA on the lower surface 50b.

  The bridge axis direction intermediate portion 50bB on the lower surface 50b of the connection floor slab 50 is gradually displaced upward from the both ends of the bridge axis direction toward the center position in the bridge axis direction. Specifically, the bridge axis direction intermediate portion 50bB of the lower surface 50b has a horizontal plane in the vicinity of the center position in the bridge axis direction, and is formed by inclined surfaces inclined at both sides in the bridge axis direction. Yes.

  At this time, the length of the connecting floor slab 50 in the bridge axis direction is set to a value of about 2600 mm. Further, the length in the bridge axis direction of the bridge axis direction intermediate portion 50bB on the lower surface 50b of the connection floor slab 50 is set to a value of about 1000 mm, and the length in the bridge axis direction in the vicinity of the center position in the bridge axis direction is set. The height is set to a value of about 600 mm.

  In this connection floor slab 50, the floor slab thickness at both ends 50bA in the bridge axis direction of the lower surface 50b is set to a value of about 220 mm, and both end positions in the bridge axis direction of the intermediate portion 50bB in the bridge axis direction of the lower surface 50b. The floor slab thickness is set to a value of about 200 mm, and the floor slab thickness in the vicinity of the center position in the bridge axis direction of the bridge axis direction intermediate portion 50bB of the lower surface 50b is set to a value of about 160 mm.

  The connection floor slab 50 is installed in place.

  At that time, both ends of the bridge floor direction in the connecting floor slab 50 are fixed to the stepped portions 12b and 14b of the main girders 12 and 14 so as to protrude upward from the bottom surfaces of the stepped portions 12b and 14b. A plurality of anchor bolts 32 arranged at a predetermined interval in the bridge axis direction and a predetermined interval in the direction orthogonal to the bridge axis so as to protrude in the bridge axis direction from the bridge axis direction end surfaces of the step-down portions 12b and 14b. It is performed via a plurality of reinforcing bars 34 arranged in the above.

  Four anchor bolts 32 are arranged at substantially equal intervals in the bridge axis direction. Further, two sets of these four anchor bolts 32 are arranged in a symmetrical relationship with respect to the direction perpendicular to the bridge axis. Each of these anchor bolts 32 has a structure in which nuts are attached to both upper and lower ends of the threaded reinforcing bar. And, as for each of these anchor bolts 32, with the lower half portion pre-embedded in each main girder 12, 14, the low elastic cement-based material constituting the connecting floor slab 50 is installed in place, The upper half is embedded in the connecting floor slab 50.

  A total of eight reinforcing bars 34 are arranged in four locations at approximately equal intervals in the vertical direction of the bridge axis in two stages, upper and lower. Each of the reinforcing bars 34 is arranged so that the tip end portion thereof extends to the vicinity of both ends in the bridge axis direction of the bridge axis direction intermediate portion 50bB on the lower surface 50b of the connection floor slab 50.

  In addition, a total of eight reinforcing bars 52 and 54 extending in the bridge axis direction are also arranged in four places at predetermined intervals in the bridge axis orthogonal direction on the connecting floor slab 50 in two upper and lower stages.

  At that time, the reinforcing bar 52 located in the upper stage extends in a straight line, and at both ends thereof, the reinforcing bar 34 located at the upper end forms a lap joint. On the other hand, the reinforcing bar 54 located in the lower stage has both ends extending linearly, but the center part is curved upward, so that the bridge axis direction intermediate part of the lower surface 50b of the connecting floor slab 50 is obtained. The required fog is secured between 50 bB. The reinforcing bar 54 located at the lower stage also forms a lap joint with the reinforcing bar 34 located at the lower stage at both ends thereof.

  A plurality of reinforcing bars 56 extending in the direction perpendicular to the bridge axis are arranged on the upper side of the reinforcing bars 52 located in the upper stage at a predetermined interval in the bridge axis direction. In addition, a plurality of reinforcing bars 58 extending in the direction perpendicular to the bridge axis are arranged at predetermined intervals in the bridge axis direction below the reinforcing bars 54 located in the lower stage. At that time, as the reinforcing bar 58, a reinforcing bar having a diameter slightly larger than that of the reinforcing bar 56 is used. Further, each of the reinforcing bars 56 and 58 is disposed so that both ends thereof protrude from the both side surfaces of the connecting floor slab 50 by a predetermined amount in the direction perpendicular to the bridge axis.

  Next, the operation of this embodiment will be described.

  FIG. 5 shows a case where a downward load P acts on one main girder 12 of a pair of main girders 12 and 14 adjacent to each other in the bridge axis direction, and the main girder 12 is deformed downward. FIG. 5 is a side view exaggeratingly showing the deformation of the connecting floor slab 50 and the other main girder 14.

  As shown in the figure, when the main girder 12 is bent downward and deformed, the connecting floor slab 50 is deformed into a substantially S shape. And the bending which arises in this connection floor slab 50 will be efficiently transmitted to the main girder 14 as a couple.

  When the connecting floor slab 50 is deformed into a substantially S shape, the bridge axis direction end portion 50bA on the main girder 12 side of the lower surface 50b tends to float up on the left side in the figure, while the main girder on the lower surface 50b. The left-hand portion 50bA on the 14th bridge axis side also tends to float up in the drawing, but a plurality of anchor bolts 32 are spaced at a predetermined interval in the bridge axis direction at both bridge axis direction both ends 50bA. Since they are arranged, these lifts are effectively suppressed.

  Moreover, since the bridge floor direction intermediate part 50bB in the lower surface 50b of the connection floor slab 50 is displaced above the bridge axis direction both ends 50bA, the connection floor slab 50 and the main girders 12 and 14 due to the above deformation are provided. Interference will be prevented in advance.

  As described above in detail, the main girder connecting structure 10 according to the present embodiment is the upper surface of the end portion on the intermediate fulcrum side (that is, the pier 16 side) in each of the pair of main girders 12 and 14 adjacent in the bridge axis direction. Are formed as stepped portions 12b, 14b displaced downward from the floor slab upper surfaces 12a, 14a by a predetermined amount, and the connecting members for connecting the pair of main girders 12, 14 are both main girders 12, 14 in the state where it is arranged so as to straddle the gap 20 between each other, it is configured as a connected floor slab 50 fixed to the stepped portions 12b, 14b of the main girders 12, 14 at both ends 50bA in the bridge axis direction. However, the connecting floor slab 50 is formed such that its upper surface 50a extends substantially flush with the floor slab upper surfaces 12a and 14a, and its lower surface 50b is in the bridge axial direction intermediate portion than the both ends 50bA in the bridge axial direction. 50bB Because it is formed so as to displace the rectangular side, it is possible to obtain the following effects.

  That is, since the member thickness of the connecting floor slab 50 is relatively thin in the intermediate portion 50bB in the bridge axis direction, it is easy to appropriately adjust the rigidity while ensuring the necessary minimum thickness as the floor slab. It becomes possible. As a result, both main girders 12 and 14 can be softly connected at the intermediate fulcrum.

  Accordingly, it is possible to reduce the cross-sectional force generated in the connecting floor slab 50 as the connecting member in accordance with the deformation of the main girder 12 (or 14). It can function as a stress transmission member.

  As described above, according to this embodiment, the main girder connecting structure 10 for connecting the main girders 12 and 14 adjacent to each other in the bridge axis direction at the intermediate fulcrum assures the required durability, and the main girder. Along with the deformation of 12 (or 14), the sectional force generated in the connecting floor slab 50 as the connecting member can be reduced, and the stress transmission between the main girders 12 and 14 can be achieved.

  Moreover, according to the present embodiment, it is possible to simplify the construction compared to the conventional main girder connection structure, and it is possible to replace the main girder connection structure 10 in the future compared to the conventional main girder connection structure. And can be easily performed.

  At that time, the connecting floor slab 50 in the present embodiment is composed of a low elastic cement-based material in which a plurality of reinforcing bars 52, 54, 56, 58 are arranged. Thus, the rigidity can be kept low and the toughness can be increased. As a result, the main girders 12 and 14 can be more easily connected softly by the connecting floor slab 50.

  Moreover, in the main girder connecting structure 10 according to the present embodiment, as the shape of the lower surface 50b of the connecting floor slab 50, the bridge axis direction intermediate portion 50bB on the lower surface 50b is located at the bridge axis direction center position from the both ends of the bridge axis direction. Since it has a shape that gradually displaces upward toward the upper side, it is possible to more effectively reduce the cross-sectional force generated in the connecting floor slab 50 with the deformation of the main girder 12 (or 14), The stress transmission between the two main girders 12 and 14 can be performed more smoothly, whereby the durability can be improved more effectively.

  Further, in the present embodiment, the fixing of the both ends 50bA in the bridge axis direction of the connecting slab 50 to the stepped portions 12b and 14b of the main girders 12 and 14 protrudes upward from the bottom surfaces of the stepped portions 12b and 14b. The plurality of anchor bolts 32 arranged at a predetermined interval in the bridge axis direction and the bridge axis orthogonal direction so as to protrude in the bridge axis direction from the bridge axis direction end faces of the stepped portions 12b and 14b Therefore, the stress transmission between the two main girders 12 and 14 can be performed more smoothly. In addition, at that time, the bending generated in the coupled floor slab 50 with the deformation of one main girder 12 (or 14) can be efficiently transmitted as a couple to the other main girder 14 (or 12).

  Next, a modification of the above embodiment will be described.

  First, a first modification of the above embodiment will be described.

  FIG. 6 is a view similar to FIG. 1 showing a main girder connecting structure 110 according to this modification.

  As shown in the figure, the main girder connecting structure 110 according to this modification is the same in the basic configuration as in the above embodiment, but the connecting floor slab 150 is more bridged than the connecting floor slab 50. It differs from the case of the said embodiment by the point currently formed in elongate to the axial direction, and the bridge axial direction intermediate part 150bB in the lower surface 150b of this connection floor slab 150 being formed in the horizontal surface over the whole region. .

  Accordingly, the step-down portions 112b and 114b of the main girders 112 and 114 are also formed long in the bridge axis direction. Further, the reinforcing bars 152 and 154 extending in the bridge axis direction arranged in two upper and lower stages in the connection floor slab 150 are formed so as to extend linearly.

  At that time, the bridge axis direction intermediate portion 150bB on the lower surface 150b of the connection floor slab 150 is set to a value of about 2000 mm in the length in the bridge axis direction, and the bridge axis direction both ends 150bA in the bridge axis direction are set. The length is set to the same value of about 800 mm as in the above embodiment. Further, the step-down portions 112b and 114b of the main girders 112 and 114 are formed so as to extend to a position about 1700 mm away from the end surface in the bridge axis direction of the main girders 112 and 114.

  In the main girder connecting structure 110 according to this modification, the upper surface 150a of the connecting floor slab 150 is formed so as to extend substantially flush with the floor slab upper surfaces 112a and 114a of the main girders 112 and 114. .

  Even in the case of adopting the configuration of this modified example, as in the case of the above embodiment, the main girder connecting structure 110 for connecting the main girders 112 and 114 adjacent to each other in the bridge axis direction at the intermediate fulcrum is required. While ensuring the durability, it is possible to reduce the cross-sectional force generated in the connecting floor slab 50 as the connecting member as the main girder 112 (or 114) is deformed, and the stress between the two main girders 112 and 114. Can communicate.

  Next, a second modification of the above embodiment will be described.

  FIG. 7 is a view similar to FIG. 1 showing a main girder coupling structure 210 according to this modification.

  As shown in the figure, the main girder connecting structure 210 according to this modification is the same in the basic configuration as in the above embodiment, but the connecting floor slab 250 is the connecting floor slab of the above embodiment. It is formed longer in the direction of the bridge axis than 50, and the configuration of the connecting floor slab 250 is different from that in the above embodiment.

  That is, in the main girder connecting structure 210 according to this modification, the connecting floor slab 250 is disposed so as to straddle the gap 20, the both ends of the precast member 250A in the bridge axis direction, and each main surface. The cast-in-place concrete 250B is placed between the stepped portions 212b and 214b of the girders 212 and 214 and end faces in the bridge axis direction.

  FIG. 8 is a detailed view of a portion VIII in FIG. 9 is a cross-sectional view taken along line IX-IX in FIG.

  As shown in these drawings, the precast member 250A is formed such that the upper surface 250Aa extends substantially flush with the floor slab upper surfaces 212a and 214a of the main girders 212 and 214, and the lower surface 250Ab is The lower surface 250Ab is formed so as to displace the bridge axis direction intermediate portion 250AbB upward from the bridge axis direction both ends 250AbA.

  The bridge axis direction intermediate portion 250AbB on the lower surface 250Ab of the precast member 250A is gradually displaced upward from the both ends of the bridge axis direction toward the center position in the bridge axis direction. Specifically, the bridge axis direction intermediate portion 250AbB of the lower surface 250Ab is formed with a horizontal plane in the vicinity of the center position in the bridge axis direction, and is formed with inclined surfaces inclined obliquely downward on both sides in the bridge axis direction. Yes.

  At this time, the length of the precast member 250A in the bridge axis direction is set to a value of about 2800 mm. The length in the bridge axis direction of the bridge axis direction intermediate portion 250AbB on the lower surface 250Ab of the precast member 250A is set to a value of about 2000 mm, and the length in the bridge axis direction in the vicinity of the center position in the bridge axis direction is set. Is set to a value of about 1600 mm.

  The precast member 250A has a floor slab thickness at the bridge axis direction both ends 250AbA of the lower surface 250Ab set to a value of about 230 mm, and at the bridge axis direction both ends of the bridge axis direction intermediate portion 250Ab of the lower surface 250Ab. The floor slab thickness is set to a value of about 200 mm, and the floor slab thickness is set to a value of about 160 mm in the vicinity of the bridge axis direction center position of the bridge axis direction intermediate portion 250AbB of the lower surface 250Ab.

  The precast member 250A is installed with a non-shrink mortar 262 having a thickness of about 10 mm between the bridge axis direction both ends 250AbA of the lower surface 250Ab and the bottom surfaces of the stepped portions 212b and 214b of the main girders 212 and 214. It is to be done in the state.

  For this reason, the bottom surfaces of the stepped portions 212b and 214b of the main girders 212 and 214 are formed at positions approximately 240 mm below the floor slab upper surfaces 212a and 214a. Each of the step-down portions 212b and 214b is formed at a position where the end surface in the bridge axis direction is separated from the end surfaces in the bridge axis direction of the main girders 212 and 214 by about 1700 mm.

  The cast-in-place concrete 250B is placed between the end surfaces in the bridge axis direction of the stepped portions 212b and 214b and the both end surfaces in the bridge axis direction of the precast member 250A.

  A plurality of openings 250Ac are formed so as to penetrate the precast member 250A in the vertical direction at the positions of both ends 250AbA in the bridge axis direction of the lower surface 250Ab of the precast member 250A. Each of these openings 250Ac has two anchor bolts near the bridge axial direction end surfaces of the main girders 212 and 214 among the anchor bolts 32 arranged at four locations in the bridge axial direction when the precast member 250A is installed. 32 for inserting 32.

  Each of these openings 250Ac is formed in a circular cross-sectional shape, and the intermediate portion in the vertical direction is formed with a larger diameter than both the upper and lower ends. The openings 250Ac are filled with non-shrink mortar 264 after the precast member 250A is installed.

  The precast member 250A is made of a low-elasticity cement-based material in which a plurality of reinforcing bars 252 and 254 extending in the bridge axis direction and a plurality of reinforcing bars 256 and 258 extending in the bridge axis orthogonal direction are arranged.

  The reinforcing bars 252 and 254 extending in the bridge axis direction are arranged in two upper and lower stages. At that time, the reinforcing bars 254 positioned in the lower stage extend in a straight line, and both end portions thereof protrude from the both end surfaces in the bridge axis direction of the precast member 250A by a predetermined amount. On the other hand, the reinforcing bar 252 located in the upper stage extends in a straight line, and after its both ends protrude from both end surfaces in the bridge axis direction of the precast member 250A, it is formed in a U shape so as to surround the distal end part of the reinforcing bar 254 located in the lower stage. After being folded and extended so as to return horizontally to the inside of the precast member 250, it bends obliquely upward and extends above the reinforcing bar 254 located at the lower stage.

  Reinforcing bars 252 located in the upper stage are arranged at eight positions at predetermined intervals in the direction orthogonal to the bridge axis. In addition, the reinforcing bars 254 located in the lower stage are arranged at six locations at predetermined intervals in the direction orthogonal to the bridge axis.

  In this modification, a reinforcing bar 234 protruding in the bridge axis direction from the bridge axis direction end surface of the stepped portions 212b and 214b of the main girders 212 and 214 is arranged so that the tip end portion protrudes in a U shape. Yes. The reinforcing bars 234 are arranged at a plurality of locations at predetermined intervals in the direction orthogonal to the bridge axis, but are arranged so that the protruding lengths are alternately shifted.

  The cast-in-place concrete 250B is in a state where the precast member 250A is installed, between the both end surfaces in the bridge axis direction of the precast member 250A and the end surfaces in the bridge axis direction of the stepped portions 212b and 214b of the main girders 212 and 214. It is formed by driving. At that time, the reinforcing bars 234 and the anchor bolts 32 project from the main girders 212 and 214 side, and the reinforcing bars 252 and 254 project from the precast member 250A. Reinforcing bars 266, 268, 270 are arranged.

  The cast-in-place concrete 250B installed in two places in this way is formed such that its upper surface 250Ba extends substantially flush with the floor slab upper surfaces 212a and 214a of the main girders 212 and 214, respectively. .

  Even in the case of adopting the configuration of this modified example, as in the case of the above-described embodiment, the main girder connecting structure 210 for connecting the main girders 212 and 214 adjacent in the bridge axis direction to each other at the intermediate fulcrum is required. While ensuring the durability, it is possible to reduce the cross-sectional force generated in the connecting floor slab 250 as the connecting member in accordance with the deformation of the main girder 212 (or 214), and the stress between the two main girders 212 and 214. Can communicate.

  In addition, when the configuration of this modification is employed, simplification of the construction of the main girder connecting structure 210 can be further promoted.

  The main girder connecting structure 210 according to the present modification has a configuration in which openings 250Ac through which the anchor bolts 32 are inserted are formed at a plurality of locations of the precast member 250A. The intermediate portion in the vertical direction is formed with a larger diameter than both the upper and lower end portions, and the anchor effect can be sufficiently ensured by filling the opening 250Ac with the non-shrink mortar 264.

  In the above modification, each opening portion 250Ac is described as having a circular cross-sectional shape, and the vertical middle portion is formed to have a larger diameter than the upper and lower end portions. It is also possible to form a cross-sectional shape (for example, an elliptical cross-sectional shape), and a bellows-like deformed sheath can be used instead of the opening 250Ac.

  In the above-described embodiment and each modified example, a reinforcing bar may be used instead of the anchor bolt 32.

  In the above embodiment and each modification, the main girders 12, 112, 212 and the main girders 14, 114, 212 adjacent to each other in the bridge axis direction have a symmetrical main girder structure with respect to the bridge axis orthogonal plane at the intermediate fulcrum. However, even when both have different main girder structures, the main girder connecting structures 10, 110, and 210 according to the above-described embodiments and the respective modifications are employed, so that The same effects as those of the embodiment and each modification can be obtained.

  In addition, the numerical value shown as a specification in the said embodiment and each modification is only an example, and of course, you may set these to a different value suitably.

10, 110, 210 Main girder connection structure 12, 14, 112, 114, 212, 214 Main girder 12a, 14a, 112a, 114a, 212a, 214a Floor slab upper surface 12b, 14b, 112b, 114b, 212b, 214b Step-down part 16 Bridge piers 20 Plays 22 Bearings 32 Anchor bolts 34, 234 Reinforcing bars 50, 150, 250 Linked floor slabs 50a, 150a, 250Aa Upper surface 50b, 150b, 250Ab Lower surface 50bA, 150bA, 250Ab Bridge axial ends 50bB, 150bB, 250Ab Bridge axial direction intermediate portion 52, 54, 152, 154, 252, 254 Reinforcement 56, 58, 256, 258, 266, 268, 270 Reinforcement 250A Precast member 250Ac Opening 250B Cast-in-place concrete 262, 2 4 non-shrink mortar

Claims (5)

A main girder connecting structure for connecting a pair of main girders adjacent in the direction of the bridge axis at the intermediate fulcrum,
The upper surface portion of the end portion on the intermediate fulcrum side in each of the pair of main girders is formed as a stepped-down portion displaced downward by a predetermined amount from the upper surface of the floor slab of the main girder,
In a state in which the connecting member that connects the pair of main girders so as to transmit stress is arranged so as to straddle the gap between the two main girders, the steps of the main girders at both ends in the bridge axis direction of the connecting members It is configured as a connected floor slab that is fixed to the lower part,
The upper surface of the connection floor slab is formed so as to extend substantially flush with the upper surface of the floor slab, and the lower surface of the connection floor slab is above the intermediate portion in the bridge axis direction than both ends in the bridge axis direction on the lower surface. A main girder connecting structure, characterized in that it is formed so as to be displaced to the side.   The main girder connection structure according to claim 1, wherein the connection floor slab is made of a low-elastic cement material in which reinforcing bars are arranged.   The bridge axis direction intermediate portion on the lower surface of the connecting floor slab is gradually displaced upward from the bridge axis direction both ends of the bridge axis direction intermediate portion toward the bridge axis direction center position. The main girder connecting structure according to claim 1 or 2.   Fixing of the both ends in the bridge axis direction in the connecting floor slab to the stepped portion of each main girder is arranged at a predetermined interval in the bridge axis direction so as to protrude upward from the bottom surface of the stepped portion. It is carried out via a plurality of anchor bolts or reinforcing bars and a plurality of reinforcing bars arranged at predetermined intervals in the bridge axis orthogonal direction so as to protrude from the bridge axis direction end face of the stepped portion. The main girder connecting structure according to any one of claims 1 to 3, wherein the main girder connecting structure is provided.   The connecting floor slab is placed between the precast member arranged so as to straddle the gap, and the bridge axis direction both end surfaces of the precast member and the bridge axis direction end surfaces of the stepped portions of the main girders, respectively. The main girder connecting structure according to any one of claims 1 to 4, wherein the main girder connecting structure is made of cast-in-place concrete.

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