Main-girder continuous rigid-joint construction method

Abstract

To provide a construction method that allows both friction welding of the connecting plate and the girder end of each girder and reduction of the negative moment based on the dead load of each girder, as well as rigidly coupling each girder to the bridge pier, and came up with the present invention. The rigid coupling method for continuing main girders according to the present invention can rigidly continue both main girders while preventing the occurrence of negative bending moment, and further, can rigidly couple the continued main girders to the bridge pier since, before placing the bridge body concrete, the connecting plate is temporarily fixed to support the left span main girder and the right span main girder simply, and since the left span main girder and the right span main girder can be connected by fully fixing the connecting plate after the slight upward displacement of the girder end of each main girder caused by placing of the bridge body concrete is adequately absorbed, and each main girder and the bridge pier are connected by the connecting bar member.

Description

Technical field

[0001] The present invention relates to a rigid coupling method for continuing main girders in multiple span girder bridges.Background Art

[0002] As shown in FIG. 1(A), a typical multiple span girder bridge has a structure in which one or more bridge piers 2 are installed between bridge abutments 1 on both banks depending on the bridge length, then multiple main girders 3 made of steels such as H-shaped steel or PC concrete are spanned between the bridge abutment 1 and the bridge pier 2, and between bridge piers 2, in parallel in the bridge width direction, respectively, and each girder ends 3a of one main girder 3 that makes up the left span and the other main girder 3 that makes up the right span are supported on the common bridge pier 2 via bearings 6.

[0003] In such a multiple span girder bridge, as shown in FIG. 1(B), based on the dead load of the main girder's own weight and the weight of the floor slab concrete, etc., or the live load of the weight of the running vehicle, etc., a large negative bending moment (the "-" moment in FIG. 1(B), i.e., bending force to make upward projection) occurs at the point where the girder end 3a of the left span main girder 3 and the girder end 3a of the right span main girder 3 are continued, and the connecting concrete 15 at the point where they are continued may crack.

[0004] The inventor has already developed a main girder continuing structure, as shown in the following Patent Document 1, which can effectively solve the above cracking problem by causing the tensile force applied to the concrete of the aforementioned continued portion due to the negative moment based on the live load to be borne by the connecting plate, while reducing the negative moment based on the dead load for the section at the point where the left span main girder and the right span main girder are continued.Citation ListPatent Document

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-154060Summary of InventionProblems to be Solved

[0006] According to the main girder continuing structure described in the above Patent Document 1, the cracking problem of the connecting concrete can be effectively prevented by causing the applied tensile force due to the negative moment based on the live load to be borne by the connecting plate, while reducing the negative moment based on the dead load, in the point where the left span main girder and the right span main girder are continued.

[0007] In constructing the main girder continuing structure described in the above Patent Document 1, the inventor of the present invention developed an innovative construction method that allows both friction welding of the connecting plate and the girder end of each girder and reduction of the negative moment based on the dead load of each girder, as well as rigidly coupling each girder to the bridge pier, and came up with the present invention.Solution to Problems

[0008] In summary, the rigid coupling method for continuing main girders according to the present invention is a rigid coupling method for continuing main girders, for connecting the girder ends of multiple left span main girders arranged in parallel in the bridge width direction and the girder ends of multiple right span main girders arranged in parallel in the bridge width direction while supporting each girder end on a common bridge pier, and for rigidly coupling each girder end to said bridge pier, and the method is characterized by the following steps A to G.

[0009] A: providing a pillow block to support a girder end of each main girder on a bridge seat surface of the bridge pier, and erecting a connecting bar member on the bridge seat surface to connect the girder end of each main girder respectively; B: supporting each girder end of each main girder via the pillow block; C: attaching a connecting plate along the girder end of each main girder at a girder upper surface side end portion of an expansion gap formed between the girder end of each main girder; D: attaching the connecting plate slidably relative to the girder end of each main girder by inserting a shaft portion of a connecting bolt into a first connecting hole, formed in the connecting plate, and a second connecting hole, formed in the girder end of each main girder, and temporarily fixing a protruding end of the shaft portion by a nut, wherein one of the first connecting hole and the second connecting hole is formed in a long hole shape extending in the bridge length direction; E: placing a bridge body concrete on each main girder and in parallel intervals in the bridge width direction of each main girder, or in parallel intervals in the bridge width direction of each main girder; F: connecting the girder end of each main girder and the connecting plate by friction joint, by fully fixing the nut which is temporarily fixed to the shaft portion of the bolt; and G: continuing the left span main girder and the right span main girder by placing a connecting concrete in the expansion gap to bury the expansion gap, the girder end of each main girder, the connecting plate and the connecting bar member, and rigidly coupling the continued each main girder and the bridge pier.

[0010] This allows the left span main girder and the right span main girder can be rigidly coupled and also each rigidly coupled main girder can be rigidly coupled to the bridge pier, while the dead load applied on the left span main girder and the right span main girder can be appropriately reduced.

[0011] Preferably, in the step A, a girder support surface of the pillow block is formed as a curved surface structure or a polygonal surface structure, so that it can adapt appropriately to the inclination and deformation of each main girder and reliably support each main girder.

[0012] In addition, the connecting bar member is inserted through a through hole formed at the girder end of each main girder, and a nut is screwed to a protruding end of the connecting bar member and the nut is fixed onto an upper surface of the girder end of each main girder directly or via a pressure-bearing member.

[0013] Alternatively, the connecting bar member is inserted in parallel intervals in the bridge width direction of each main girder, and the connecting bar member is inserted through a pressure-bearing member that is laid across the bridge width direction on the upper surface of the girder end of each main girder, and a nut is screwed to a protruding end of the connecting bar member.

[0014] This ensures that the girder end of each main girder is securely connected to the bridge pier.Effect of the Invention

[0015] According to the rigid coupling method for continuing main girders of the present invention, the left span main girder and the right span main girder can be rigidly continued and also, they are rigidly coupled to the bridge pier, while the dead load applied on the left span main girder and the right span main girder can be appropriately reduced. Therefore, the occurrence of cracks in the connecting concrete can be effectively prevented, and a rigid frame structure can be constructed in which the left span main girder, the right span main girder and the bridge pier are rigidly connected and integrated.Brief Description of Drawing

[0016] FIG. 1(A) is a side view schematically showing a typical multiple span girder bridge, and FIG. 1(B) shows a distribution diagram of bending moment that occurs in the multi span girder bridge. FIG. 2 is an explanatory diagram showing a step of supporting each of a left span main girder and right span main girder, which are made of H-shaped steel, on a bridge seat surface of a bridge pier via a pillow block. FIG. 3 is an explanatory diagram showing a step of attaching a connecting plate to girder ends of the left span main girder and the right span main girder and fixing it by bolt. FIG. 4 is an explanatory diagram showing a state in which the left span main girder and the right span main girder are connected by the connecting plate. FIG. 5 is a cross-sectional view in the bridge length direction showing continued structure of main girders. FIG. 6 is a cross-sectional view of the continued structure of main girders in a plane (cross-sectional view taken along line A-A in FIG. 5). FIG. 7 is a cross-sectional view in the width direction of the bridge showing the continued structure of main girders (cross-sectional view taken along line B-B in FIG. 5). FIG. 8 is other cross-sectional view in the width direction of the bridge showing the continued structure of main girders (cross-sectional view taken along line C-C in FIG. 5). FIG. 9 is an explanatory diagram showing the state in which a second connecting hole of the girder end of each main girder is formed in long hole shape. FIG. 10 is a cross-sectional view showing a pillow block which has a girder support surface formed as a polygonal surface structure. FIG. 11 is a cross-sectional view in the bridge length direction showing continued structure using girders made of concrete. FIG. 12 is a cross-sectional view in the bridge width direction showing continued structure using girders made of concrete (cross-sectional view taken along line D-D in FIG. 11). FIG. 13 is a cross-sectional view in the bridge width direction showing continued structure using girders made of concrete (cross-sectional view taken along line E-E in FIG. 11). Description of Embodiments

[0017] Hereinafter, best embodiments of a rigid coupling method for continuing main girders according to the present invention will be described with reference to FIGs. 1 to 13.

[0018] As mentioned above, as shown in FIG. 1(A), the typical multiple span girder bridge has a structure in which one or more bridge piers 2 are installed between bridge abutments 1 on both banks depending on the bridge length, then multiple main girders 3 made of steels such as H-shaped steel or PC concrete are spanned between the bridge abutment 1 and the bridge pier 2, and between bridge piers 2, in parallel in the bridge width direction, respectively.

[0019] More specifically, the main girder 3 that makes up the left span and the main girder 3 that makes up the right span are supported on the bridge seat surface 2a of one bridge pier 2 via bearings 6, and an expansion gap 5 is formed between the left span main girder 3 and the right span main girder 3, in particular, between girder end surfaces 3b of each girder end 3a, and the left span main girder 3 and the right span main girder 3 are in disconnected structure formed by the expansion gap 5, and the connecting concrete 15 is placed into the expansion gap 5 to continue the left span main girder 3 and the right span main girder 3.

[0020] The rigid coupling method for continuing main girders according to the present invention is a method for constructing a main girder continuing structure as shown in FIGs. 5 to 8, FIG. 11 and FIG. 12, i.e., for constructing the main girder continuing structure that can cause the tensile force applied to the connecting concrete 15 due to the negative moment based on the live load generated after completion of the bridge to be borne by the connecting plate 7, while reducing the negative moment based on the dead load, by coupling the girder end 3a of the left span main girder 3 and the girder end 3a of the right span main girder 3 via the connecting plate 7 extending along both girder ends 3a at a girder upper surface side end portion 5a of an expansion gap 5 while uncoupling at a girder lower surface side end portion 5b of the expansion gap 5, and burying the expansion gap 5, the girder ends 3a of left and right main girders 3 and the connecting plate7 in the connecting concrete 15. In addition, it is a method for constructing a rigid coupling structure in which the continued main girders 3 and the bridge pier 2 are rigidly coupled via a connecting bar member 19 and the connecting concrete 15.

[0021] FIGs. 2 to 9 shows examples in which an H-shaped steel is used as the span main girder 3, and each of the left span main girder 3 and the right span main girder 3, both formed by H-shaped steel, has a web 3c, an upper flange 3d extending along the upper end of the web 3c, and a lower flange 3e extending along the lower end of the same. Note that, as described later, in the rigid coupling method for continuing main girders, the shape of the shape steel used as the main girder 3 and the shape of the shape steel joint provided to the concrete main girder 3 may be arbitrarily selected depending on the implementation.< Pillow Block Providing Step>

[0022] In the rigid coupling method for continuing main girders according to the present invention, as shown in FIG. 2, first, a pillow block 4 for supporting the girder end 3a of the left span main girder 3 and the pillow block 4 for supporting the girder end 3a of the right span main girder 3 are provided on a bridge seat surface 2a of the common bridge pier for supporting the left span main girder 3 and the right span main girder 3.

[0023] To describe the pillow block 4 in detail, the pillow block 4 is made of concrete, metal or synthetic resin, and is provided continuously in the bridge width direction, as shown in FIG. 7. Preferably, as shown in FIG. 2, etc., the girder support surface (upper surface) 4a of the pillow block 4 has a curved surface structure, or as shown in FIG. 10, the girder support surface 4a has a polygonal surface structure consisting of a large number of small width surfaces 4b, so that it can support each main girder 3 in response to its inclination and deformation.

[0024] In addition, as shown in FIG. 2, a connecting bar member 19 is erected on the bridge seat surface 2a on which the pillow block 4 is provided, to connect each girder end 3a of the left span main girder 3 and the right span main girder 3 respectively.

[0025] The connecting bar member 19 is formed of a steel bar such as a reinforcing bar, and the lower end of the steel bar is buried integrally into the concrete bridge pier 2 and erected from the bridge seat surface 2a. Alternatively, a cable may be used instead of the steel bar.

[0026] In case that the steel bar is used as the connecting bar member 19, as shown in FIGs. 5, 8, 11 and 12, the end portion of the reinforcing steel bar 22 buried in the concrete bridge pier 2 is allowed to protrude upward from the bridge seat surface 2a, and the protruding portion can be used as the connecting bar member 19.

[0027] In addition, as shown in FIGs. 8 and 12, the connecting bar member 19 is erected from directly below the girder end 3a of each main girder 3 on the bridge seat surface 2a, and can also be elected from directly below the parallel interval in the bridge width direction of the girder end 3a of each main girder 3 (the interval between adjacent main girders 3 in the bridge width direction). Alternatively, depending on the implementation, it is also optional to erect the connecting bar member 19 only from directly below the girder end 3a of each main girder 3 on the bridge seat surface 2a, or only from directly below the parallel interval in the bridge width direction of the girder end 3a of each main girder 3.<Main Girder Supporting Step>

[0028] As shown in FIG. 2, each girder end 3a of the left span main girder 3 and the right span main girder 3 is supported on the bridge seat surface 2a of the bridge pier 2 by the lower flange 3e via the pillow block 4 provided as described above. In this case, the curved or polygonal surface structure of the girder support surface 4a of the pillow block 4 can absorb the inclination of the main girder 3 etc., and since it has no corners, the pillow block 4 itself can be effectively prevented from chipping.

[0029] In addition, as already described, when connecting bar member 19 that erects from directly below the girder end 3a of each main girder 3 is provided, the connecting bar member 19 is inserted through each girder end 3a of the left span main girder 3 and the right span main girder 3, as shown in FIGs. 8 and 12. Specifically, the connecting bar member 19 is inserted through the penetration holes 23 provided in the upper flange 3d and the lower flange 3e at each girder end 3a of the left span main girder 3 and the right span main girder 3, from bottom to top. The screwing of the nut 20 onto the protruding end of the inserted connecting bar member 19 will be described later.

[0030] In addition, as described above, when the connecting bar member 19 that erects from directly below the parallel interval in the bridge width direction of the girder end 3a of each main girder 3 is provided, the connecting bar member 19 is inserted into the parallel interval as shown in FIGs. 8 and 12. The screwing of the nut 20 onto the upper end of the inserted connecting bar member 19 will be described later.<Connecting Plate Attaching Step, Connecting Plate Temporarily Fixing Step>

[0031] Next, as shown in FIG. 3, the connecting plate 7 is attached along the girder end 3a of each main girder 3 at the girder upper surface side end portion 5a of the expansion gap 5 formed between the girder end surface 3b of the left spam main girder 3 and the girder end surface 3b of the right span main girder 3, and a shaft portion of a connecting bolt 12 is inserted into a first connecting hole 10 drilled at the girder end 3a of each main girder 3 and a second connecting hole 11 drilled at the connecting plate 7, then the connecting plate 7 is temporarily fixed by temporarily fixing the protruding end of the shaft portion by a nut 13. On the other hand, a girder lower surface side end portion 5b of the expansion gap 5 is in unconnected state.

[0032] Specifically, a connecting plate 7 is attached across the upper surface 8A of the upper flange 3d of both girder ends 3a of the left span main girder 3 and the right span main girder 3, and similarly, a connecting plate 7 is attached across the lower surfaces 8B of the upper flange 3d of both girder ends 3a, while the lower flange 3e of both girder ends 3a is in unconnected state.

[0033] A pair of connecting plates 7 overlapping each upper surface 8A of the upper flanges 3d of both girder ends 3a are arranged in parallel with an interval 9 between them, and a pair of connecting plates 7 overlapping each lower surface 8B of the upper flanges 3d of both girder ends 3a are also arranged in parallel with an interval 9 between them. This allows the interval 9 to communicate with the expansion gap 5, and allows air to be removed from the interval 9 when placing the connecting concrete 15 described below, allowing the connecting concrete 15 to be filled evenly.

[0034] In addition, a plurality of first connecting holes 10 are drilled in the connecting plate 7, and a plurality of second connecting holes 11 corresponding to the first connecting holes 10 are drilled in the upper flanges 3d of each of the girder ends, and the first and second connecting holes 10, 11 are aligned with each other, then the shaft portion of the connecting bolt 12 is inserted into the first and second connecting holes 10, 11, and the protruding end (male threaded end) of the shaft portion is temporarily fixed with a nut 13. Preferably, the shaft portion of the connecting bolt 12 is inserted from the lower surface 8B side of the upper flange 3d of each girder end 3a and protruded from the upper surface 8A side, making it easier to perform the nut tightening operation.

[0035] In the present invention, as shown in FIG. 3, by forming first connecting hole 10 provided in abovementioned connecting plate 7 in long hole shape extending in the bridge length direction or, as shown in FIG. 9, by forming the second connecting hole 11 drilled in the girder end 3a of each main girder in long hole shape extending in the bridge length direction, even after the connecting bolt 12 is inserted into the first connecting hole 10 or the second connecting hole, the connecting plate 7 or the connecting bolt 12 can be shifted in the bridge length direction. Therefore, the connecting plate 7 can be fixed slidably relative to the girder end 3a of each main girder 3. This makes it possible to prevent the occurrence of negative bending moment due to the weight of each main girder 3 and the weight of the bridge body concrete (the floor slab concrete 14, the slab concrete 24, and the filling concrete 27) described below, i.e., dead load.

[0036] In addition, the high-strength bolt for friction joint is used as the connecting bolt 12, and the temporary fixing of the nut 13 to the shaft of the connecting bolt 12 is performed such that the connecting plate 7 and the upper surface 8A of the upper flange 3d, or the connecting plate 7 and the lower surface 8B of the upper flange 3d are closely contacted with each other to the extent that no foreign matter such as gravel can get between them, while the connecting plate 7 can slide relatively against the girder end 3a of each main girder 3.

[0037] Preferably, when the connecting plate 7 is attached across the girder end 3a of each main girder 3 as described above, a paint such as zinc-rich primer is used to ensure an appropriate slip coefficient. This is to achieve a stronger friction joint and a stronger rigid coupling structure for continuing main girders.<Bridge Body Concrete Placing Step>

[0038] Next, the bridge body concrete is placed on each main girder 3 and in parallel intervals in the bridge width direction of each main girder 3, or in parallel intervals in the bridge width direction of each main girder 3. The bridge body concrete is placed on / in each part.

[0039] As shown in FIGs. 5 to 8, when steel girders such as H-shaped steels are used as main girders 3, the floor slab concrete 14 (bridge body concrete) is placed onto the left span main girder 3 and the right span main girder 3, respectively, and the slab concrete 24 (bridge body concrete) is placed within the parallel intervals of the left span main girders 3 in the bridge width direction and within the parallel intervals of the right span main girders 3, respectively.

[0040] In this step, although the girder end 3a of each main girder 3 is displaced by increase of the dead load, the displacement is absorbed by the shift of the connecting plate 7 or the connecting bolt 12. In other words, the long hole shape of the first connecting hole 10 or the second connecting hole 11 for connecting the connecting plate 7 and the temporary fastening state of the connecting bolt 12 and the nut 13 absorbs the displacement and prevents the generation of negative bending moment. Furthermore, the curved shape or polygonal shape of the girder support surface 4a of each pillow block 4 also contribute to absorbing the displacement of the girder end 3a of each main girder3.

[0041] Describing the concrete placement in detail, the slab concrete 24 is placed into the space defined by the upper and lower flanges 3d, 3e and webs 3c of left span main girders 3 adjacent in the bridge width direction, and then the floor slab concrete 14 is placed onto left span main girders 3. Similarly, the slab concrete 24 is placed into the space defined by the upper and lower flanges 3d, 3e and webs 3c of the right span main girders 3 adjacent in the bridge width direction, and then the floor slab concrete 14 is placed continuously onto right span main girders 3.

[0042] In other words, the opening 25', extending in the bridge length direction formed between lower flanges 3e of left span main girders 3 adjacent in the bridge width direction, is closed with a closing member, and the slab concrete 24 is placed into the above-mentioned space through the opening 25 extending in the bridge length direction formed between upper flanges 3d adjacent in the bridge width direction of left span main girders 3, and then the floor slab concrete 14 is placed continuously onto left span main girders 3.

[0043] Similarly, the opening 25', extending in the bridge length direction formed between lower flanges 3e of right span main girders 3 adjacent in the bridge width direction, is closed with the closing member, and the slab concrete 24 is placed into the above-mentioned space through the opening 25 extending in the bridge length direction formed between upper flanges 3d adjacent in the bridge width direction of right span main girders 3, and then the floor slab concrete 14 is placed continuously onto right span main girders 3.

[0044] In addition, as shown in FIGs. 11 to 13, when a PC concrete girder is used as the left span main girder 3 and the right span main girder 3, the girder end 3a of each main girder 3 can be constructed with a joint 3a' made of H-shaped steel, in other words, each girder end 3a of the left span main girder 3 and the right span main girder 3 made of PC concrete can be formed by the joint 3a' having a web 3c, an upper flange 3d extending along the upper end of the web 3c and a lower flange 3e extending along the lower end of the web 3c. Note that 3b' in FIG. 11 is the end surface of the shaped steel joint 3a', and the expansion gap 5 is formed between joint end surfaces 3b' of each of the left and right span main girders 3.

[0045] In this way, when the PC concrete girder is used as each main girder 3, in the pillow block providing step, the main girder supporting step, the connecting plate attaching step, and the connecting plate temporarily fixing step, it can be applied simply by replacing the upper and lower flanges 3d, 3e of the H-shaped steel girder described above with the upper and lower flanges 3d, 3e of the H-shaped steel joint 3a', however, in this step, as shown in FIG. 12, the filling concrete 27 (bridge body concrete) is placed into the parallel intervals (adjacent intervals) of left span main girders 3 in the bridge width direction and the parallel intervals (adjacent intervals) of right span main girders 3 in the bridge width direction to integrate multiple main girders 3 adjacent in the bridge width direction.

[0046] The filling concrete 27 is placed through an opening 25 extending in the bridge length direction formed on the upper side of the left span main girders 3 adjacent in the bridge width direction, while the opening 25' extending in the bridge length direction formed on the lower side of the left span main girders 3 adjacent in the bridge width direction is closed with a closing member. Similarly, the filling concrete 27 is placed through an opening 25 extending in the bridge length direction formed on the upper side of the right span main girders 3 adjacent in the bridge width direction, while the opening 25' extending in the bridge length direction formed on the lower side of the right span main girders 3 adjacent in the bridge width direction is closed with a closing member.<Connecting Plate Fully Fixing Step>

[0047] After placing the bridge body concrete (the floor slab concrete 14 and the slab concrete 24 or the filling concrete 27) as described above, the nut 13 that is temporarily fixed to the shaft of the bolt 12 in the connecting plate temporary fixing step is fully fixed, and the connecting plate 7 is fully fixed to the girder end 3a of each main girder 3. This allows each girder end 3a of the left span main girder 3 and the right span main girder 3 to be firmly connected to the connecting plate 7 by friction welding.

[0048] In addition, as shown in FIGs. 8 and 12, the nut 20 is screwed onto the protruding end of the connecting bar member 19 inserted through the girder end 3a of each main girder 3, and the nut 20 is fixed to the upper surface of the girder end 3a of each main girder 3. That is, a nut 20 is screwed onto the protruding end (male threaded end) of the connecting bar member 19 protruding from the upper surface 8A of the upper flange 3d of each girder end 3a, and the nut 20 is fixed to the upper surface 8A of the upper flange 3d. The nut 20 fixed to the upper surface 8A of the upper flange 3d is fixed directly to the upper surface 8A of the upper flange 3d or is fixed to the upper surface 8A of the upper flange 3d via a pressure-bearing member 21. The pressure-bearing member 21 extends as across the girder ends 3a arranged in parallel in the bridge width direction, and is laid across the upper surface 8A of the upper flange 3d of each girder end 3a.

[0049] In addition, for the connecting bar member 19 inserted into the parallel interval (adjacent interval) in the bridge width direction of the left span main girder 3 and the parallel interval (adjacent interval) in the bridge width direction of the right span main girder 3, their upper ends are inserted through the portion 21a of the pressure-bearing member 21 extending between the main girders 3, i.e., the pressure-bearing member portion 21a extending between the upper flanges 3d, and the nut 20 is screwed onto it, then the nut 20 is fixed to the upper surface of the pressure-bearing member portion 21a.<Connecting Concrete Placing Step>

[0050] Finally, formwork is assembled and the connecting concrete 15 is placed onto the bridge seat surface 2a of the bridge pier 2 through the expansion gap 5, and the expansion gap 5, the girder ends 3a of the left span main girder 3 and the right span main girder 3, the connecting plate 7 and the connecting bar member 19 are buried in the connecting concrete 15.

[0051] Preferably, the connecting concrete 15 is placed before the placed bridge body concrete (the floor slab concrete 14, the slab concrete 24, and the filling concrete 27), as described above, hardens. This is to allow the connecting concrete 15 and the bridge body concrete to harden together in an intimate and close manner.

[0052] As explained above, in the present invention, the generation of negative bending moments based on the dead load can be prevented by connecting the girder end 3a of the left span main girder 3 and the girder end 3a of the right span main girder 3 via the connecting plate 7 after generation of the dead load by the bridge body concrete (the floor slab concrete 14 and the slab concrete 24 or the filling concrete 27) at the girder upper surface side end portion 5a of the expansion gap 5.

[0053] In other words, since, before placing the bridge body concrete, the connecting plate 7 is temporarily fixed to support the left span main girder 3 and the right span main girder 3 simply, and since the left span main girder 3 and the right span main girder 3 can be connected by fully fixing the connecting plate 7 after the slight upward displacement of the girder end 3a of each main girder 3 caused by placing of the bridge body concrete is adequately absorbed, both main girders 3 can be rigidly continued while preventing the occurrence of negative bending moment, and further, the continued main girders 3 can be rigidly coupled to the bridge pier 2.

[0054] After the connecting concrete 15 has hardened, a pavement 26 is applied, then the rigid coupling structure for continuing main girders shown in FIGs. 5 to 8 and FIGs. 11 to 13 is completed.

[0055] Note that, after completion, a tensile force will be applied to the upper portion of the connecting concrete 15 due to a negative bending moment based on the live load applied to the left span main girder 3 and the right span main girder 3 or the weight of the pavement 26 (dead load), however, this tensile force is appropriately borne by the connecting plate 7, and the occurrence of cracks in the connecting concrete 15 can be effectively prevented.

[0056] In addition, in the present invention, the rigid coupling structure for continuing main girders can be strengthened by inserting multiple connecting bar members 16 made of steel bar such as PC cable, solid wire etc. extending in the bridge width direction through insert holes 17 drilled in each girder end 3a between each girder end 3a of the left span main girders 3 adjacent in the bridge width direction at intervals along the bridge length direction and burying them in connecting concrete 15, together with inserting other multiple connecting bar members 16 made of abovementioned steel bar extending in the bridge width direction through insert holes 17 drilled in each girder end 3a between each girder end 3a of the right span main girders 3 adjacent in the bridge width direction at intervals along the bridge length direction and burying them in connecting concrete 15.

[0057] To restate, as shown in FIG. 7, connecting bar members 16 are inserted through insert holes 17 so as to penetrate the web 3c at the girder end 3a of each main girder 3, which is made of H-shaped steel arranged in parallel in the bridge width direction, and are fastened by nuts 18 on the outer surfaces of the web 3c at the girder end 3a of the main girder 3 at both ends in the bridge width direction. In addition, as shown in FIG. 12, even when the main girder 3 made of PC concrete is used, they are inserted through insert holes 17 so as to penetrate the web 3c at the joint 3a' and are fastened by nuts 18 on the outer surfaces of the web 3c at the girder end 3a of the main girder 3 at both ends in the bridge width direction.

[0058] Alternatively, the connecting concrete 15 can be reinforced by giving prestress force to it by inserting the connecting bar member 16, loosely inserted into a pipe member 16' extending in the bridge width direction, between each girder end 3a of the left span main girders 3 adjacent in the bridge width direction and burying them in the connecting concrete 15, together with inserting the connecting bar member 16, loosely inserted into other pipe member 16' extending in the bridge width direction, between each girder end 3a of the right span main girders 3 adjacent in the bridge width direction and burying them in the connecting concrete 15, then tensioning the connecting bar member 16.

[0059] Furthermore, as shown in FIGs. 8 and 13, the slab concrete 24 or the filling concrete 27 can be reinforced by giving prestress force to it by inserting a number of connecting bar members 16 or connecting bar members 16 loosely inserted into connecting pipe members 16' along the entire length of the bridge length direction of each web 3c of the left span main girder 3 and the right span main girder 3 at intervals in the bridge length direction.

[0060] In the present invention, the connection using the connecting plate 7 does not necessarily have to connect both the upper surface 8A and the lower surface 8B of each upper flange 3d of the girder ends 3a or the joints 3a' of both main girders 3 as in the already described embodiments, but it is also possible to only connect either the upper surface 8A or the lower surface 8B of each upper flange 3d.

[0061] In addition, in the present invention, plate member, channel member or flat bar member can be adopted as the connecting plate 7, and as long as it can be arranged across the upper flanges 3d of both girder ends 3a or both joints 3a' and overlapping the upper flanges 3d, the case in which members other than those mentioned above are used as the connecting plate 7 is included. In addition, it is preferable that the connecting plate 7 is a solid plate made of steel material having high tensile strength.

[0062] In addition, in the present invention, the case in which the connecting plate 7 placed on the upper surface 8A between the upper flanges 3d of both girder ends 3a or both joints 3a' is made wide, and one connecting plate 7 is placed overlapping the upper surface 8A without forming an interval 9 as in the above embodiments is included.

[0063] Furthermore, in the present invention, the case in which, instead of the main girder 3 made of H-shaped steel as described above, a main girder 3 made of shape steel having an upper flange 3d, such as a T-shaped steel, I-shaped steel, or π-shaped steel, is used and upper flanges 3d of main girders 3 are connected with a connecting plate 7 to construct a continuous rigidly connected structure is included. In addition, the case in which, instead of the joint 3a' made of the H-shaped steel described above, a joint 3a' made of a structural steel having an upper flange 3d, such as a T-shaped steel, an I-shaped steel, or a π-shaped steel, is used and the upper flange 3d of the joint 3a' is connected with the above-mentioned connecting plate 7 to construct a continuous rigidly connected structure is included.Reference Signs List

[0064] 1···bridge abutment, 2···bridge pier, 2a···bridge seat surface, 3···main girder (left span main girder, right span main girder), 3a···girder end, 3a'···joint, 3b···girder end surface, 3b' ··· joint end surface, 3c···web, 3d···upper flange, 3e···lower flange, 4···pillow block, 4a···girder support surface, 4b···small width surface, 5···expansion gap, 5a···girder upper surface side end portion, 5b···girder lower surface side end portion, 6··· bearing, 7···connecting plate, 8A···upper surface of upper flange, 8B···lower surface of lower flange, 9···interval, 10···first connecting hole, 11···second connecting hole, 12···connecting bolt, 13···nut, 14···floor slab concrete (bridge body concrete), 15···connecting concrete, 16···connecting bar member, 16'··· pipe member, 17···insert hole, 18···nut, 19···connecting bar member, 20··· nut, 21···pressure-bearing member, 21a···pressure-bearing member portion, 22···reinforcing steel bar, 23···penetration hole, 24··· slab concrete (bridge body concrete), 25, 25'···opening, 26··· pavement, 27···the filling concrete (bridge body concrete)

Claims

1. A rigid coupling method for continuing main girders for connecting the girder ends of multiple left span main girders arranged in parallel in the bridge width direction and the girder ends of multiple right span main girders arranged in parallel in the bridge width direction while supporting each girder end on a common bridge pier, and for rigidly coupling each girder end to said bridge pier, and the method is <b>characterized by the following steps A to G. A: providing a pillow block to support a girder end of each main girder on a bridge seat surface of the bridge pier, and erecting a connecting bar member on the bridge seat surface to connect the girder end of each main girder respectively; B: supporting each girder end of each main girder via the pillow block; C: attaching a connecting plate along the girder end of each main girder at a girder upper surface side end portion of an expansion gap formed between the girder end of each main girder; D: attaching the connecting plate slidably relative to the girder end of each main girder by inserting a shaft portion of a connecting bolt into a first connecting hole, formed in the connecting plate, and a second connecting hole, formed in the girder end of each main girder, and temporarily fixing a protruding end of the shaft portion by a nut, wherein one of the first connecting hole and the second connecting hole is formed in a long hole shape extending in the bridge length direction; E: placing a bridge body concrete on each main girder and in parallel intervals in the bridge width direction of each main girder, or in parallel intervals in the bridge width direction of each main girder; F: connecting the girder end of each main girder and the connecting plate by friction joint, by fully fixing the nut which is temporarily fixed to the shaft portion of the bolt; and G: continuing the left span main girder and the right span main girder by placing a connecting concrete in the expansion gap to bury the expansion gap, the girder end of each main girder, the connecting plate and the connecting bar member, and rigidly coupling the continued each main girder and the bridge pier.

2. The rigid coupling method for continuing main girders according to Claim 1, wherein in the step A, a girder support surface of the pillow block is formed as a curved surface structure or a polygonal surface structure.

3. The rigid coupling method for continuing main girders according to Claim 1, wherein the connecting bar member is inserted through a through hole formed at the girder end of each main girder, and a nut is screwed to a protruding end of the connecting bar member and the nut is fixed onto an upper surface of the girder end of each main girder directly or via a pressure-bearing member.

4. The rigid coupling method for continuing main girders according to Claim 1, wherein the connecting bar member is inserted in parallel intervals in the bridge width direction of each main girder, and the connecting bar member is inserted through a pressure-bearing member that is laid across the bridge width direction on the upper surface of the girder end of each main girder, and a nut is screwed to a protruding end of the connecting bar member.

Images