Precast prestressed concrete deck structure and construction method

Abstract

To provide a floor slab structure and a construction method for the same that can suppress cracks in a concrete section near an expansion device without using a PCa member extending in an oblique direction in a precast prestressed concrete floor slab structure arranged at an end fulcrum of an abutment having an oblique angle with respect to the bridge axis direction and a construction method for the same.SOLUTION: A floor slab structure 1 includes: a plurality of ramp PCa members 6 extending in the bridge width direction; and oblique tension members 7 inserted into all of the ramp PCa members 6 in the vicinity of an expansion device 3. The ramp PCa members 6 are adjacent to each other in the bridge axis direction and have oblique sides 11 extending along the expansion direction of the expansion device 3 in the vicinity of the expansion device 3 in a plan view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a precast prestressed concrete deck structure arranged near the end supports of an abutment that is at an oblique angle to the bridge axis. [Background technology]

[0002] When constructing a concrete deck, precast concrete (hereinafter referred to as "PCa") members are sometimes used to shorten the construction period and stabilize the quality. In addition, in a reinforced concrete structure, the tensile force is borne by the reinforcing bars, which causes fine cracks to form on the concrete surface. There is a concern that salt from the freeze-thaw agent on the bridge surface will seep through the cracks, causing corrosion of the reinforcing bars. Therefore, in order to prevent cracks from forming in the concrete due to tensile forces, prestress is sometimes applied to the PCa members of the deck structure (for example, Non-Patent Documents 1 to 3).

[0003] The deck structures described in Non-Patent Documents 1 to 3 have an oblique angle at the abutment. Therefore, in the deck structures described in Non-Patent Documents 1 and 2, a part of the part adjacent to the expansion joint is made of cast-in-place reinforced concrete. In the deck structure described in Non-Patent Document 3, PCa extending in an oblique direction is placed at the end, and the part between it and the standard part is made of cast-in-place concrete. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] IHI Techniques, Vol.56, No.1(2016), pp.56-64 [Non-Patent Document 2] Proceedings of the 29th Symposium of the Japan Society of Prestressed Concrete Engineering (2020), pp.577-580 [Non-Patent Document 3] Proceedings of the 29th Symposium of the Japan Society of Prestressed Concrete Engineering (2020), pp.573-576 Summary of the Invention [Problem to be solved by the invention]

[0005] The deck structures described in Non-Patent Documents 1 and 2 had the risk of the cast-in-place reinforced concrete sections having poor quality, such as poor durability, or of cracks causing corrosion of the reinforcing bars.

[0006] The PCa members extending in a diagonal direction described in Non-Patent Document 3 do not conform to the original design method in which the deck is supported by the main girder and designed in a direction perpendicular to the main girder. In addition, designing the PCa members in a diagonal direction causes problems such as a decrease in the efficiency of the tension members placed in the precast prestressed concrete deck, twisting during temporary placement or lifting, and the length of each PCa member becomes long, making transportation difficult.

[0007] In view of the above background, the present invention aims to provide a precast prestressed concrete deck structure and a construction method thereof, which are arranged near the end supports of an abutment that has an oblique angle with respect to the bridge axis direction, and which can suppress the occurrence of cracks in the concrete portion near the expansion joint without using PCa members extending diagonally. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, one aspect of the present invention is a precast prestressed concrete deck structure (1, 31) arranged adjacent to an expansion device (3) installed on an abutment having an oblique angle with respect to the bridge axis direction, the structure comprising a plurality of inclined precast concrete members (6, 32) extending in the bridge width direction or the bridge axis direction, the inclined precast concrete members (6, 32) having oblique sides (11) extending along the extension direction of the expansion device (3) near the expansion device (3) in a plan view and adjacent to each other, and diagonal tendons (7) extending in the extension direction of the expansion device (3) and inserted into all of the inclined precast concrete members (6, 32) near the expansion device (3).

[0009] According to this aspect, by using the inclined precast concrete member having an oblique side, it is not necessary to use a PCa member that extends at an angle in the bridge width direction. Also, since prestress is introduced to the inclined precast concrete member having an oblique side by the diagonal tension member, it is possible to suppress cracks occurring in the concrete part of the deck structure near the expansion joint and corrosion of the reinforcing bars caused by the cracks.

[0010] In the precast prestressed concrete deck structure (1) of the above aspect, the multiple inclined precast concrete members (6) may extend in the bridge width direction and be adjacent to each other in the bridge axis direction.

[0011] According to this aspect, the installation position of each inclined precast concrete member can be easily grasped based on the extension direction length of the inclined precast concrete member, making construction management easier.

[0012] In the precast prestressed concrete deck structure (1) of the above-described embodiment, the inclined precast concrete member (6) includes an end-most precast concrete member (12) which is positioned closest to the expansion device in the bridge axis direction and has a generally triangular shape in a plan view, and an intermediate precast concrete member (13) which is positioned more centrally in the bridge axis direction than the end-most precast concrete member (12) and has a generally trapezoidal shape in a plan view, and each of the intermediate precast concrete members (13) includes a bridge width direction tendon (10) extending in the bridge width direction.

[0013] According to this aspect, the bridge width direction tendons can prevent cracks from occurring in the concrete portion of the intermediate precast concrete member when the intermediate precast concrete member is erected by a crane.

[0014] In the precast prestressed concrete deck structure (1) of the above-mentioned embodiment, at the corners of the endmost precast concrete member (12) and the intermediate precast concrete member (13) formed by the hypotenuse (11) and the side extending in the bridge width direction in a plan view, the point where the extension lines of both sides intersect at an acute angle forms a chamfered portion (15) having a chamfered shape at a surface intersecting in the bridge width direction, and one of the diagonal tension members (7) may pass through the chamfered portion (15).

[0015] According to this aspect, by providing the chamfered portion, the diagonal tendons can be positioned close to the expansion device in the inclined precast concrete member, and the diagonal tendons and reinforcing bars can be evenly positioned.

[0016] In the precast prestressed concrete deck structure (31) of the above aspect, the multiple inclined precast concrete members (32) may extend in the bridge axis direction and be adjacent to each other in the bridge width direction on the main girder.

[0017] According to this aspect, the inclined portion precast concrete member can be made larger than the endmost precast concrete member described above, resulting in good construction efficiency.

[0018] In the precast prestressed concrete deck structure (31) of the above aspect, each of the inclined precast concrete members (32) may include a bridge axial direction tendon (35) extending in the bridge axial direction.

[0019] According to this aspect, prestress is introduced by the bridge axial direction tendons, so that the occurrence of cracks in the inclined precast concrete members is suppressed during erection by a crane.

[0020] The precast prestressed concrete deck structure (31) of the above-mentioned aspect may further comprise a lateral tension member (33) arranged on the opposite side of the diagonal tension member (7) in the bridge axis direction, extending parallel to the bridge width direction, and inserted into all of the inclined precast concrete members, and an intermediate tension member (34) arranged between the diagonal tension member (7) and the lateral tension member (33) in the bridge axis direction, and inclined at an angle smaller than the diagonal tension member (7) with respect to the bridge width direction.

[0021] According to this embodiment, by introducing prestress using the lateral tendons and intermediate tendons, cracks in the concrete in the area away from the expansion joint 3 and corrosion of the reinforcing bars caused by the cracks are suppressed.

[0022] In the precast prestressed concrete deck structure (31) of the above aspect, The plurality of inclined portion precast concrete members include a plurality of first inclined portion precast concrete members and a second inclined portion precast concrete member having a length in an extension direction shorter than a length in an extension direction of the first inclined portion precast concrete members, The intermediate tendons (34) are composed of first intermediate tendons (34a) inserted into all of the inclined precast concrete members (32). 、 2 or more The first Inserted into the sloped precast concrete member (32), The second The inclined precast concrete member (32) may include a second intermediate tendon (34b) that is not inserted therein.

[0023] According to this aspect, the installation interval of the intermediate tendons can be kept within a predetermined range.

[0024] One aspect of the present invention is a method for constructing a precast prestressed concrete deck structure (1, 31) arranged adjacent to an expansion device (3) installed on an abutment having an oblique angle with respect to the bridge axis direction, the method comprising the steps of: arranging a plurality of inclined precast concrete (PCa) members (6, 32) extending in the bridge width direction or the bridge axis direction, the inclined precast concrete members (6, 32) having oblique sides (11) extending along the extension direction of the expansion device (3) in the vicinity of the expansion device (3) in a plan view, adjacent to each other on a main girder (2); inserting diagonal tension members (7) in the vicinity of the expansion device (3) in the inclined precast concrete members (6, 32) so as to extend parallel to the extension direction of the expansion device (3) and pass through all of the inclined precast concrete members (6, 32); and tensioning the diagonal tension members (7).

[0025] According to this aspect, by using the inclined precast concrete member having an oblique side, it is not necessary to use a PCa member that extends at an angle in the bridge width direction. Also, since prestress is introduced into the inclined precast concrete member having an oblique side by the diagonal tension member, it is possible to suppress cracks occurring in the concrete part of the deck structure near the expansion joint and corrosion of the reinforcing bars caused by the cracks.

[0026] In the method for constructing the precast prestressed concrete deck structure (1) of the above aspect, the multiple inclined precast concrete members (6) extend in the bridge width direction and are adjacent to each other in the bridge axis direction, and the inclined precast concrete members (6) include an end-most precast concrete member (12) that is positioned closest to the expansion joint (3) in the bridge axis direction and is positioned on one of the main girders (2), and an intermediate precast concrete member (13) that is positioned on two or more of the main girders (2), and the placing step may include connecting the end-most precast concrete member (12) and one of the intermediate precast concrete members (13) adjacent to the end-most precast concrete member (12) to each other after transporting them to a construction site, and then placing them on the main girders (2).

[0027] According to this aspect, by connecting the endmost precast concrete member, which is difficult to stabilize on the main girder by itself, to the middle precast concrete member and then erecting it, the endmost precast concrete member becomes stable on the main girder even while the deck structure is in the middle of construction.

[0028] In the method for constructing the precast prestressed concrete deck structure (1) of the above aspect, the plurality of inclined precast concrete members (6) extend in the bridge width direction and are adjacent to each other in the bridge axis direction, the inclined precast concrete members (6) are placed on two or more of the main girders (2), and the method further includes a step of constructing a cast-in-place concrete section (12') adjacent to the expansion device (3) and placed on one of the main girders (2) between the placing step and the inserting step, and in the inserting step, the diagonal tendons (7) may also be inserted into the cast-in-place concrete section (12').

[0029] According to this embodiment, the cast-in-place concrete section can be stabilized on the main girder 2 by shoring or the like, and prestress can be introduced into the cast-in-place concrete section to suppress cracks and corrosion of the reinforcing bars.

[0030] The method for constructing the precast prestressed concrete deck structure (1, 31) of the above aspect may further include a step of pouring PCa member-filling concrete (19) between the plurality of inclined precast concrete members (6, 32) prior to the tensioning step, and the main girder (2) may include a slip-stop member embedded in the PCa member-filling concrete (19).

[0031] According to this embodiment, the diagonal tension member is tensioned after pouring the filler concrete between the PCa members, so construction is possible even if the anti-slip member is located in a position where it is embedded in the filler concrete between the PCa members.

[0032] The method for constructing the precast prestressed concrete deck structure (1, 31) of the above aspect further includes a step of pouring PCa member-filling concrete (19) between the plurality of inclined precast concrete members (6, 32) after the tensioning step, and the main girder does not need to include a slip stopper member embedded in the PCa member-filling concrete (19).

[0033] According to this embodiment, the filling concrete between the PCa members is poured after the diagonal tendons are tensioned, so that the deck structure is not subjected to a restraining force from the main girder when the diagonal tendons are tensioned. Effect of the Invention

[0034] According to the above aspects, in a precast prestressed concrete deck structure arranged adjacent to an expansion joint extending at an angle to the width direction of the bridge, and a construction method thereof, it is possible to provide a deck structure and a construction method thereof that can suppress the occurrence of cracks in the concrete portion near the expansion joint without using PCa members extending diagonally. [Brief description of the drawings]

[0035] [Figure 1] Plan view of the deck structure according to the first embodiment [Diagram 2] Reinforcement diagram of II-II section in Figure 1 [Diagram 3] Plan view of the deck structure according to the second embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figures 1 and 2 show a precast prestressed concrete floor slab structure (hereinafter, referred to as "floor slab structure") 1 according to a first embodiment.

[0037] The deck structure 1 is disposed on the main girder 2 and is adjacent to an expansion device 3 installed on an abutment (not shown) having an oblique angle with respect to the bridge axis direction. The main girder 2 is, for example, composed of multiple steel girders extending in the bridge axis direction and spaced apart from each other in the bridge width direction. The main girder 2 has a slip stopper member (not shown) such as a headed stud protruding upward from its upper surface, and the deck structure 1 may be a composite deck in which the slip stopper member is embedded. The expansion device 3 is installed between the abutment (not shown) and the deck structure 1, and its extension direction is inclined with respect to the bridge width direction in a plan view. Here, the "bridge width direction" is a direction parallel to the upper surface of the deck structure 1 and perpendicular to the bridge axis direction.

[0038] The deck structure 1 comprises a plurality of normal PCa members 5 each having a rectangular shape in plan view, a plurality of inclined PCa members 6 arranged between the expansion device 3 and the normal PCa members 5 and adjacent to the expansion device 3, diagonal tension members 7 arranged along the extension direction of the expansion device 3, and filling concrete 8. Of the plurality of normal PCa members 5, the normal PCa members 5 adjacent to the inclined PCa members 6 have a downdraft (thickened portion on the underside of the deck) on the expansion device 3 side relative to the middle portion in the bridge axis direction.

[0039] The normal PCa member 5 includes reinforcing bars 9 arranged in two upper and lower tiers so as to extend in the bridge axis direction and the bridge width direction, and bridge width direction tension members 10 arranged in two upper and lower tiers so as to extend in the bridge width direction. The bridge width direction tension members 10 extend over the entire length of the normal PCa member 5 in the bridge width direction, and are fixed to the concrete portion of the normal PCa member 5 in a tensioned state.

[0040] Each of the inclined PCa members 6 has an oblique side 11 extending in the extension direction of the expansion device 3 in a plan view near the expansion device 3. The inclined PCa members 6 include one end portion PCa member 12 that is arranged closest to the expansion device 3 in the bridge axis direction and to which one end portion of the diagonal tension member 7 is fixed, one or more intermediate PCa members 13 that are arranged more centrally than the end portion PCa member 12 in the bridge axis direction, and an anchoring PCa member 14 that is arranged closest to the center in the bridge axis direction among the inclined PCa members 6 and to which the other end portion of the diagonal tension member 7 is fixed.

[0041] The endmost PCa member 12 has a generally triangular shape in plan view. This triangular shape is composed of one side along one side edge (the lower side in FIG. 1) of the deck structure 1, one side extending in the bridge width direction, and one oblique side 11. The endmost PCa member 12 includes reinforcing bars 9 extending in the bridge axis direction and the bridge width direction, but no tendons are installed during factory fabrication. Depending on the member dimensions of the endmost PCa member 12, bridge width direction tendons 10 may be installed in the endmost PCa member 12 during factory fabrication.

[0042] The intermediate PCa member 13 has a generally trapezoidal shape in plan view. This trapezoidal shape is composed of one side along one side edge (the lower side in FIG. 1) of the deck structure 1, two sides extending in the bridge width direction, and an oblique side 11. As with the normal PCa member 5, the intermediate PCa member 13 includes reinforcing bars 9 arranged in two upper and lower stages so as to extend in the bridge axis direction and the bridge width direction, and bridge width direction tendons 10 arranged in two upper and lower stages so as to extend in the bridge width direction. In the corners formed by the oblique side 11 and the side extending in the bridge width direction in plan view of the end PCa 12 member and the intermediate PCa member 13, the points where the extensions of both sides intersect at an acute angle form chamfered portions 15 that are chamfered on a surface perpendicular to the bridge width direction.

[0043] The anchoring PCa member 14 is adjacent to the normal PCa member 5 and has a generally pentagonal shape in plan view. This pentagonal shape is composed of two sides along both side edges of the deck structure 1, two sides extending in the bridge width direction, and one oblique side 11. The reinforcing bars 9 and bridge width direction tendons 10 are arranged in the same manner as the normal PCa member 5 and the intermediate PCa member 13.

[0044] The reinforcing bars 9 extending in the bridge axis direction of the normal PCa member 5 and the inclined PCa member 6 (hereinafter referred to as "PCa members 5, 6" when referring to both the normal PCa member 5 and the inclined PCa member 6) protrude in a loop shape from the end faces in the bridge axis direction of the concrete parts of the PCa members 5, 6, and form loop joints with the reinforcing bars 9 of other PCa members 5, 6 adjacent in the bridge axis direction. The PCa members 5, 6 are provided with box punching holes 4 that penetrate in the vertical direction. The box punching holes 4 receive anti-slip members and are filled with concrete.

[0045] The diagonal tendons 7 are arranged along the extension direction of the expansion device 3 so as to span almost the entire length in the bridge width direction. In the illustrated example, three mutually parallel diagonal tendons 7 are used. The diagonal tendons 7 arranged closest to the expansion device 3 pass through the chamfered portions 15 of the end PCa member 12 and the middle PCa member 13. It is preferable that the diagonal tendons 7 are arranged almost evenly in the direction perpendicular to the diagonal tendons 7 in the end PCa member 12. One end of the diagonal tendons 7 is fixed to the end PCa member 12 via a fixing tool (not shown), and the other end is fixed to the fixing PCa member 14 via a fixing tool (not shown). The surfaces of the end PCa member 12 and the fixing PCa member 14 to which the diagonal tendons 7 are fixed are constituted by cutout portions 16 cut perpendicular to the diagonal tendons 7.

[0046] The diagonal tendons 7 are disposed within a sheath 17. The sheath 17 includes a portion embedded within the inclined PCa member 6 and a portion embedded in the filling concrete 8. The sheath 17 embedded within the inclined PCa member 6 is disposed between the reinforcing bars 9 and the bridge width direction tendons 10 disposed at the upper part and the reinforcing bars 9 and the bridge width direction tendons 10 disposed at the lower part. The diagonal tendons 7 and the bridge width direction tendons 10 are made of PC steel bars, PC steel wires, PC steel strands, or fiber-reinforced plastics such as carbon fiber or aramid fiber.

[0047] The filling concrete 8 includes end filling concrete 18 poured on site between the expansion device 3 and the inclined PCa member 6, and PCa member-to-PCa member filling concrete 19 poured on site between the PCa members 5, 6.

[0048] We will now explain a method for constructing the deck structure 1. The construction method includes manufacturing the PCa members 5, 6 in a factory, transporting the PCa members 5, 6 to a construction site, arranging the PCa members 5, 6 on the main girders 2, arranging and tensioning the diagonal tendons 7, and pouring the filling concrete 8.

[0049] The PCa members 5, 6 are fabricated in a factory. Workers assemble the reinforcing bars 9, place the bridge width direction tendons 10, install formwork (not shown), pour concrete into the formwork while applying tension to the bridge width direction tendons 10, and remove the formwork after the concrete hardens. For the inclined PCa member 6, workers place the portion of the sheath 17 to be embedded in the inclined PCa member in a predetermined position before pouring the concrete. The chamfered portion 15 is formed by placing a corresponding formwork. The tension of the bridge width direction tendons 10 may be performed by a post-tensioning method instead of a pre-tensioning method. After curing, the PCa members 5, 6 are transported to the construction site.

[0050] At the construction site, workers use a crane or the like to place the PCa members 5, 6 on the main girder 2. After that, the workers weld the slip prevention members to the upper surface of the main girder 2 within the box punching holes 4.

[0051] In addition, when there is one main girder 2 supporting the endmost PCa member 12, there is a risk that the endmost PCa member 12 will not be stable on the main girder 2. In this case, workers may connect the endmost PCa member 12 to one intermediate PCa member 13 to be placed adjacent to it on the ground at the construction site, and then use a crane or the like to place it on the main girder 2. Also, instead of using the endmost PCa member 12, a structure equivalent to the endmost PCa member 12 may be constructed on site by assembling rebar and pouring concrete (cast-in-place concrete section 12').

[0052] Next, the worker places the portion of the sheath 17 to be embedded in the filling concrete 19 between the PCa members at a predetermined position between the inclined PCa members 6.

[0053] Next, the worker fills the box punch holes 4 of the PCa members 5 and 6 with concrete and pours the filling concrete 19 between the PCa members. As a result, the slip stopper is embedded in the concrete in the box punch holes 4 and in the filling concrete 19 between the PCa members. After the filling concrete 19 between the PCa members hardens, the worker inserts the diagonal tendon 7 into the sheath 17 and tensions the diagonal tendon 7. If the slip stopper is not in a position where the filling concrete 19 between the PCa members should be poured, it is preferable to fill the box punch holes 4 with concrete and pour the filling concrete 19 between the PCa members after tensioning the diagonal tendon 7.

[0054] Next, the worker pours end filling concrete 18 between the oblique side 11 of the inclined PCa member 6 and the expansion device 3.

[0055] The function and effect of the deck structure 1 will be described.

[0056] By using multiple inclined PCa members 6 that have oblique sides 11 and extend in the bridge width direction, it is possible to place PCa members in portions adjacent to the expansion devices 3 extending in oblique directions without using PCa members extending in oblique directions. Furthermore, the installation position of each inclined PCa member 6 can be easily grasped based on the extension length of the inclined PCa members 6, facilitating construction management.

[0057] By using the diagonal tendons 7, prestress can be introduced throughout the section adjacent to the expansion joint 3, thereby suppressing cracking of the concrete and corrosion of the reinforcing bars 9 caused by the cracking.

[0058] Prestress is introduced in the extension direction of the normal PCa member 5, the intermediate PCa member 13, and the anchoring PCa member 14, which have a longer extension length than the endmost PCa member 12, by the bridge width direction tendons 10. This prevents cracks from occurring in the normal PCa member 5, the intermediate PCa member 13, and the anchoring PCa member 14 during erection by a crane. Furthermore, since the bridge width direction tendons 10 exist even in positions away from the diagonal tendons 7, the occurrence of cracks in the normal PCa member 5, the intermediate PCa member 13, and the anchoring PCa member 14 and corrosion of the reinforcing bars 9 due to cracks are prevented in the completed deck structure 1.

[0059] By providing chamfered portions 15 on the endmost PCa member 12 and the middle PCa member 13, the diagonal tension members 7 can be positioned close to the expansion device 3 in the inclined PCa member 6, and the diagonal tension members 7 and the reinforcing bars 9 can be positioned approximately evenly.

[0060] When there is only one main girder 2 supporting the endmost PCa member 12, the endmost PCa member 12 is connected to the adjacent middle PCa member 13 before being erected on the main girder 2, so that the endmost PCa member 12 is stable on the main girder 2 even immediately after erection. When a cast-in-place concrete section 12' is constructed on the main girder 2 instead of the endmost PCa member 12, the cast-in-place concrete section 12' is stabilized on the main girder 2 by supports or the like until it is connected to the middle PCa member 13.

[0061] When filling the box-punched holes 4 with concrete and pouring the filling concrete 19 between the PCa members before tensioning the diagonal tension member 7, construction is possible even if the anti-slip member is in a position where it is embedded in the filling concrete 19 between the PCa members.

[0062] If the slip stopper members are not positioned to be embedded in the filling concrete 19 between the PCa members, after the diagonal tendons 7 are tensioned, concrete is filled into the box holes 4 to pour the filling concrete 19 between the PCa members. Therefore, when the diagonal tendons 7 are tensioned, the deck structure 1 is not subjected to a restraining force from the main girders 2.

[0063] A deck structure 31 according to the second embodiment will be described with reference to Fig. 3. In the description, components common to the first embodiment will be denoted by the same reference numerals and explanations thereof will be omitted. The deck structure 31 is disposed on the main girder 2 and is adjacent to an expansion joint 3 installed on an abutment having an oblique angle with respect to the bridge axis direction.

[0064] The deck structure 31 comprises a plurality of normal PCa members 5 which are rectangular in a plan view, a plurality of inclined PCa members 32 which are arranged between the expansion device 3 and the normal PCa members 5 and adjacent to the expansion device 3, a diagonal tension member 7 which extends along the extension direction of the expansion device 3 near the expansion device 3, a lateral tension member 33 which is inserted parallel to the bridge width direction on the side opposite the expansion device 3 in the plurality of inclined PCa members 32, and an intermediate tension member 34 which is arranged between the diagonal tension members 7 and the lateral tension members 33 in the bridge axis direction and which is inclined at an angle smaller than the diagonal tension member 7 with respect to the bridge width direction.

[0065] Each of the inclined PCa members 32 extends in the bridge axis direction, and one end edge in the bridge axis direction in plan view constitutes a hypotenuse 11 parallel to the extension direction of the expansion device 3. The other end edges of each of the inclined PCa members 32 in the bridge axis direction are aligned with each other in the bridge width direction and adjacent to the normal PCa member 5. The inclined PCa members 32 arranged closer to one side in the bridge width direction (lower in the paper of FIG. 3) have a shorter length in the extension direction, and the inclined PCa members 32 arranged closer to the other side (upper in the paper of FIG. 3) have a longer length in the extension direction. The inclined PCa members 32 include reinforcing bars 9 (see FIG. 2) extending in two stages, up and down, in the bridge axis direction and generally in the bridge width direction (including a direction inclined to the same extent as the expansion device 3 with respect to the bridge width direction), and bridge axis direction tension members 35 extending in two stages, up and down, in the bridge axis direction.

[0066] A shoulder surface 36 is provided at the end of each of the inclined PCa members 32 on the expansion device 3 side in the bridge axis direction, and the expansion device 3 is partially supported on the shoulder surface 36. Mortar or end filling concrete 18 (see Figure 1) may be provided between the expansion device 3 and the multiple inclined PCa members 32. The inclined PCa members 32 do not need to be provided with a shoulder surface 36.

[0067] Each diagonal tendon 7 is inserted into all the inclined PCa members 32 along the extension direction of the expansion device 3 so as to span almost the entire length in the width direction of the bridge. The diagonal tendon 7 arranged closest to the expansion device 3 passes under the shoulder surface 36. In the illustrated example, four diagonal tendons 7 are arranged, and it is preferable that the intervals between these diagonal tendons 7 be approximately equal.

[0068] Each of the lateral tendons 33 is inserted into all of the inclined PCa members 32 so as to be parallel to the bridge width direction and extend over approximately the entire length in the bridge width direction. In the illustrated example, three lateral tendons 33 are arranged, and it is preferable that the intervals between these lateral tendons 33 are approximately equal.

[0069] The intermediate tension members 34 include a plurality of first intermediate tension members 34a that pass through all the inclined PCa members 32 so as to span substantially the entire length in the bridge width direction, and a plurality of second intermediate tension members 34b that are each inserted into two or more inclined PCa members 32 on the side with the longer extension length (in the illustrated example, the two on the upper side of the paper in the figure). The first intermediate tension members 34a and the second intermediate tension members 34b are arranged alternately. The second intermediate tension members 34b are provided to prevent the intervals between the intermediate tension members 34 from becoming too wide. In the illustrated example, four first intermediate tension members 34a and five second intermediate tension members 34b are arranged, and it is preferable that the intervals between these intermediate tension members 34 are substantially uniform.

[0070] The side surface of the inclined PCa member 32 to which the diagonal tendons 7, lateral tendons 33 and intermediate tendons 34 are fixed has a cutout portion 37 having a surface to which a fastening device (not shown) is fixed perpendicular to the extension direction of each of the tendons 7, 33 and 34. The portion of the deck structure 31 in the bridge width direction to which the second intermediate tendon 34b is fixed is a box cutout portion 38. A box cutout portion 39 is also formed in the portion that receives the slip prevention member.

[0071] The side surfaces of the inclined PCa members 32 are parallel to the vertical direction and extend generally in the bridge axis direction. However, the end sides in the bridge axis direction of the abutting side surfaces of adjacent inclined PCa members 32 are formed in a stepped shape. For this reason, the peripheral areas through which the diagonal tendons 7 and the intermediate tendons 34 (which are inclined at a relatively large angle with respect to the bridge width direction) arranged on the expansion device 3 side among the intermediate tendons 34 pass are abutted against each other on surfaces perpendicular to the extension directions of the diagonal tendons 7 and the intermediate tendons 34. Mortar (not shown) or PCa member filler concrete 19 may be provided between the adjacent inclined PCa members 32.

[0072] The diagonal tendons 7, lateral tendons 33, intermediate tendons 34 and bridge axis tendons 35 are made of PC steel bars, PC steel wires, PC steel strands, or fiber-reinforced plastics such as carbon fiber or aramid fiber.

[0073] A method for constructing the deck structure 31 will be described below. The construction method includes manufacturing the normal PCa members 5 and the inclined PCa members 32 (hereinafter, when referring to both the normal PCa members 5 and the inclined PCa members 32, they will be referred to as "PCa members 5, 32") in a factory, transporting the PCa members 5, 32 to the construction site, arranging the PCa members 5, 32 on the main girder 2, and arranging and tensioning the diagonal tendons 7, lateral tendons 33, and intermediate tendons 34.

[0074] The PCa members 5, 32 are manufactured in a factory. The manufacturing process of the normal PCa member 5 is the same as that of the first embodiment. For the inclined PCa member 32, workers assemble the reinforcing bars 9, place the bridge axis direction tendons 35, place the sheaths 17 (see FIG. 2) for the diagonal direction tendons 7, the lateral direction tendons 33 and the intermediate portion tendons 34, install a formwork (not shown), pour concrete into the formwork while applying tension to the bridge axis direction tendons 35, and remove the formwork after the concrete has hardened. The tension of the bridge axis direction tendons 35 may be introduced by a post-tensioning method instead of a pre-tensioning method. After curing, the PCa members 5, 32 are transported to the construction site.

[0075] At the construction site, workers use a crane or the like to place the PCa members 5, 32 on the main girder 2, insert the diagonal tendons 7, lateral tendons 33 and intermediate tendons 34 into the sheath 17, and tension the diagonal tendons 7, lateral tendons 33 and intermediate tendons 34.

[0076] The function and effect of the deck structure 31 will be described.

[0077] By using multiple inclined PCa members 32 that have oblique sides 11 and extend in the bridge axis direction, it is possible to place PCa members in the portion adjacent to the expansion device 3 that extends in the oblique direction without using PCa members that extend in the oblique direction. Also, there is no need to provide a relatively small PCa member like the end-most PCa member 12 (see Figure 1) in the first embodiment, which improves construction efficiency.

[0078] By introducing prestress into the entire portion adjacent to the expansion gear 3 using the diagonal tendons 7, cracking of the concrete near the expansion gear 3 and corrosion of the reinforcing bars 9 caused by the cracking are suppressed. Furthermore, by introducing prestress into the portion away from the expansion gear 3 using the lateral tendons 33 and intermediate tendons 34, cracking of the concrete in the portion away from the expansion gear 3 and corrosion of the reinforcing bars 9 caused by the cracking are suppressed.

[0079] Since prestress is introduced by the bridge axis direction tendons 35 in the extension direction of the inclined PCa member 32, the occurrence of cracks in the inclined PCa member 32 is suppressed during erection by a crane.

[0080] Since the abutting sides of the inclined PCa members 32 are partially stepped, the prestress from the diagonal tendons 7 and the intermediate tendons 34, which have a relatively large inclination from the bridge width direction, is efficiently transmitted between the inclined PCa members 32.

[0081] Although the description of the specific embodiment is finished above, the present invention is not limited to the above embodiment and modified examples, and can be modified in a wide range of ways. The numbers of diagonal tendons 7, lateral tendons 33, and intermediate tendons 34 may be changed. The chamfered portion 15 may intersect with the bridge axis direction at an angle other than perpendicular. [Explanation of symbols]

[0082] 1,31: Precast prestressed concrete deck structure 2: Main digit 3: Telescopic device 6,32: Inclined PCa member 7: Diagonal tendons 10: Bridge width direction tension material 11: Hypotenuse 12: Endmost PCa member 12': Cast-in-place concrete section 13: Intermediate PCa member 14: PCa member for fixing 15: Chamfered part 19: Concrete filling between PCa members 33: Lateral tension material 34: Intermediate tension material 35: Bridge axial tension member

Claims

1. A precast prestressed concrete deck structure arranged adjacent to an expansion joint installed on an abutment having an oblique angle with respect to the bridge axis direction, A plurality of inclined precast concrete members extending in the bridge width direction or the bridge axis direction, the inclined precast concrete members having oblique sides extending along the extension direction of the expansion device in the vicinity of the expansion device in a plan view and adjacent to each other; a diagonal tendon extending in the extension direction of the expansion device and inserted into all of the inclined precast concrete members in the vicinity of the expansion device; A precast prestressed concrete deck structure.

2. 2. The precast prestressed concrete deck structure according to claim 1, wherein the plurality of inclined precast concrete members extend in the bridge width direction and are adjacent to each other in the bridge axis direction.

3. The inclined portion precast concrete member includes an end portion precast concrete member arranged closest to the expansion device in the bridge axis direction and having a generally triangular shape in a plan view, and an intermediate portion precast concrete member arranged in the center in the bridge axis direction relative to the end portion precast concrete member and having a generally trapezoidal shape in a plan view, 3. The precast prestressed concrete deck structure according to claim 2, wherein each of the intermediate precast concrete members includes a bridge width direction tendon extending in the bridge width direction.

4. 4. The precast prestressed concrete deck structure of claim 3, wherein at the corners of the endmost precast concrete member and the intermediate precast concrete member formed by the hypotenuse and the side extending in the bridge width direction in a plan view, the points where the extension lines of both sides intersect at an acute angle form a chamfered portion having a chamfered shape at a surface intersecting in the bridge width direction, and one of the diagonal tension members passes through the chamfered portion.

5. 2. The precast prestressed concrete deck structure according to claim 1, wherein the plurality of inclined precast concrete members extend in the bridge axis direction and are adjacent to each other in the bridge width direction on the main girder.

6. The precast prestressed concrete deck structure according to claim 5 , wherein each of the inclined precast concrete members includes a bridge axial direction tendon extending in the bridge axial direction.

7. A lateral tendon is disposed on the opposite side of the diagonal tendon in the bridge axis direction, extends parallel to the bridge width direction, and is inserted into all of the inclined portion precast concrete members; an intermediate tendon arranged between the diagonal tendon and the lateral tendon in the bridge axis direction and inclined at an angle smaller than that of the diagonal tendon with respect to the bridge width direction; The precast prestressed concrete deck structure according to claim 5 or 6, further comprising:

8. The plurality of inclined precast concrete members include a plurality of first inclined precast concrete members and a second inclined precast concrete member having an extension length shorter than the extension length of the first inclined precast concrete members, 8. The precast prestressed concrete deck structure of claim 7, wherein the intermediate tendons include a first intermediate tendon inserted into all of the inclined precast concrete members, and a second intermediate tendon inserted into two or more of the first inclined precast concrete members and not inserted into the second inclined precast concrete members.

9. A method for constructing a precast prestressed concrete deck structure adjacent to an expansion joint installed on an abutment having an oblique angle with respect to the bridge axis direction, comprising: A step of arranging a plurality of inclined precast concrete (PCa) members extending in the bridge width direction or the bridge axis direction, the inclined precast concrete members having oblique sides extending along the extension direction of the expansion device in the vicinity of the expansion device in a plan view, adjacent to each other on the main girder; inserting a diagonal tendon in the vicinity of the expansion device in the precast concrete member of the inclined section so as to extend parallel to the extension direction of the expansion device and pass through all of the precast concrete member of the inclined section; tensioning the diagonal tendons; A method for providing the above.

10. The plurality of inclined precast concrete members extend in the bridge width direction and are adjacent to each other in the bridge axis direction, The inclined portion precast concrete member includes an end portion precast concrete member disposed closest to the expansion device in the bridge axis direction and disposed on one of the main girders, and an intermediate portion precast concrete member disposed on two or more of the main girders, 10. The method of claim 9, wherein the placing step includes connecting the endmost precast concrete members and one of the intermediate precast concrete members adjacent to the endmost precast concrete members to each other after transportation to a construction site and then placing the endmost precast concrete members on the main girder.

11. The plurality of inclined precast concrete members extend in the bridge width direction and are adjacent to each other in the bridge axis direction, The inclined portion precast concrete member is disposed on two or more of the main girders, The method further includes the step of constructing a poured concrete section adjacent to the expansion joint and disposed on one of the girder, the poured concrete section being disposed between the placing step and the inserting step; 10. The method of claim 9, wherein in the inserting step, the diagonal tendons are also inserted into the poured concrete section.

12. The step of pouring concrete between the precast concrete members in the inclined portion between the plurality of precast concrete members in the inclined portion before the tensioning step is further provided; The method according to any one of claims 9 to 11, wherein the main girder includes a stopper member embedded in the filling concrete between the PCa members.

13. The step of pouring concrete between the plurality of inclined portion precast concrete members after the tensioning step is further provided; The method according to any one of claims 9 to 11, wherein the main girder does not include a stopper member embedded in the filling concrete between the PCa members.

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