JP7669249B2 - Precast prestressed concrete deck structure and construction method - Google Patents

Description

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 direction.

When constructing a concrete deck, precast concrete (hereinafter referred to as "PCa") members are sometimes used to shorten construction time and stabilize quality. In addition, in reinforced concrete structures, 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 and cause 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).

The deck structures described in Non-Patent Documents 1 to 3 have an oblique angle at the abutment. For this reason, in the deck structures described in Non-Patent Documents 1 and 2, a portion of the area adjacent to the expansion device is constructed from cast-in-place reinforced concrete. In the deck structure described in Non-Patent Document 3, PCa extending diagonally is placed at the end, and the area between it and the standard section is made of cast-in-place concrete.

IHI Technique, Vol. 56, No. 1 (2016), pp. 56-64 Proceedings of the 29th Symposium of the Japan Society of Prestressed Concrete Engineering (2020), pp. 577-580 Proceedings of the 29th Symposium of the Japan Society of Prestressed Concrete Engineering (2020), pp. 573-576

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.

The diagonally extending PCa members described in Non-Patent Document 3 do not conform to the original design method of designing the deck as a deck supported by the main girder in a direction perpendicular to the main girder. In addition, designing the PCa members diagonally reduces the efficiency of the tension members placed in the precast prestressed concrete deck, causes twisting when temporarily placed or lifted, and makes transportation difficult because each PCa member is longer.

In view of the above background, the present invention aims to provide a precast prestressed concrete deck structure and a construction method thereof that is arranged near the end support of an abutment that has an oblique angle with respect to the bridge axis direction, and that can suppress the occurrence of cracks in the concrete portion near the expansion joint without using PCa members that extend diagonally.

In order to solve the above problem, 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, and includes 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) adjacent to each other and having oblique sides (11) extending along the extension direction of the expansion device (3) near the expansion device (3) in a plan view, and diagonal tension members (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).

According to this aspect, by using a precast concrete member with an inclined side, it is not necessary to use a PCa member that extends at an angle in the width direction of the bridge. In addition, because prestress is introduced into the precast concrete member with an inclined side by a 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 these cracks.

In the precast prestressed concrete deck structure (1) of the above embodiment, 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.

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

In the precast prestressed concrete deck structure (1) of the above embodiment, the inclined precast concrete members (6) include end precast concrete members (12) that are positioned closest to the expansion device in the bridge axis direction and have a roughly triangular shape in plan view, and intermediate precast concrete members (13) that are positioned more centrally in the bridge axis direction than the end precast concrete members (12) and have a roughly trapezoidal shape in plan view, and each of the intermediate precast concrete members (13) includes a bridge width direction tension member (10) that extends in the bridge width direction.

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.

In the precast prestressed concrete deck structure (1) of the above embodiment, in the corners of the end precast concrete member (12) and the intermediate precast concrete member (13) formed by the oblique side (11) 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 chamfered portions (15) that are chamfered at the surface that intersects in the bridge width direction, and one of the diagonal tension members (7) may pass through the chamfered portion (15).

According to this aspect, by providing a chamfered portion, the diagonal tension member can be positioned close to the expansion device in the inclined precast concrete member, and the diagonal tension member and reinforcing bar can be evenly positioned.

In the precast prestressed concrete deck structure (31) of the above embodiment, 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.

According to this aspect, the inclined precast concrete member can be made larger than the end-most precast concrete member described above, which improves construction efficiency.

In the precast prestressed concrete deck structure (31) of the above embodiment, each of the inclined precast concrete members (32) may include a bridge axis direction tension member (35) extending in the bridge axis direction.

According to this aspect, prestress is introduced by the bridge axial tension members, which prevents cracks from occurring in the inclined precast concrete members during erection by a crane.

The precast prestressed concrete deck structure (31) of the above embodiment may further include a lateral tension member (33) that is arranged on the opposite side of the diagonal tension member (7) in the bridge axis direction, extends parallel to the bridge width direction, and is inserted into all of the inclined precast concrete members, and an intermediate tension member (34) that is arranged between the diagonal tension member (7) and the lateral tension member (33) in the bridge axis direction and is inclined at an angle smaller than the diagonal tension member (7) with respect to the bridge width direction.

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

In the precast prestressed concrete deck structure (31) of the above-mentioned aspect, the multiple inclined portion precast concrete members include multiple first inclined portion precast concrete members and second inclined portion precast concrete members whose length in the extension direction is shorter than the length in the extension direction of the first inclined portion precast concrete members, and the intermediate tension members (34) may include a first intermediate tension member (34a) inserted into all of the inclined portion precast concrete members (32) , and a second intermediate tension member (34b) inserted into two or more of the first inclined portion precast concrete members (32) and not inserted into the second inclined portion precast concrete members (32).

This allows the installation interval of the intermediate tension members to be kept within a specified range.

One aspect of the present invention is a method for constructing a precast prestressed concrete deck structure (1, 31) adjacent to an expansion device (3) installed on an abutment having an oblique angle with respect to the bridge axis direction, 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 the 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 that the diagonal tension members (7) 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).

According to this aspect, by using a precast concrete member with an inclined side, it is not necessary to use a PCa member that extends at an angle in the width direction of the bridge. In addition, because prestress is introduced into the precast concrete member with an inclined side by a 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 these cracks.

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, and the inclined precast concrete members (6) include an end precast concrete member (12) that is disposed closest to the expansion joint (3) in the bridge axis direction and disposed on one of the main girders (2), and an intermediate precast concrete member (13) that is disposed on two or more of the main girders (2), and the disposing step may include, after transportation to the construction site, connecting the end precast concrete member (12) and one of the intermediate precast concrete members (13) adjacent to the end precast concrete member (12) to each other and then disposing them on the main girders (2).

According to this aspect, the end-most precast concrete member, which is difficult to stabilize on the main girder by itself, is connected to the middle precast concrete member before erection, so that the end-most precast concrete member is stable on the main girder even during construction of the deck structure.

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').

According to this embodiment, the cast-in-place concrete section can be stabilized on the main girder 2 by using 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.

The method for constructing the precast prestressed concrete deck structure (1, 31) of the above aspect further includes a step of pouring PCa member inter-part 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 inter-part concrete (19).

According to this embodiment, the diagonal tensioning 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.

The method for constructing the precast prestressed concrete deck structure (1, 31) of the above aspect further includes a step of pouring PCa member inter-part 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 inter-part concrete (19).

According to this embodiment, the filler concrete is poured between the PCa members after the diagonal tendons are tensioned, so the deck structure is not subjected to a restraining force from the main girder when the diagonal tendons are tensioned.

According to the above aspects, in a precast prestressed concrete deck structure arranged adjacent to an expansion joint that extends at an angle relative to the width direction of the bridge, and a method for constructing the same, it is possible to provide a deck structure and a method for constructing the same that can suppress the occurrence of cracks in the concrete portion near the expansion joint without using PCa members that extend diagonally.

Plan view of the deck structure according to the first embodiment Reinforcement diagram of II-II section in Figure 1 Plan view of the deck structure according to the second embodiment

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 and 2 show a precast prestressed concrete slab structure (hereinafter, referred to as "slab structure") 1 according to the first embodiment.

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) that is at an oblique angle 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 prevention 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 prevention 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 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.

The deck structure 1 comprises a plurality of regular PCa members 5 that are rectangular in plan view, a plurality of inclined PCa members 6 that are arranged between the expansion device 3 and the regular 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 infill concrete 8. Of the multiple regular PCa members 5, the regular PCa members 5 adjacent to the inclined PCa members 6 are downcast (thickened part of the underside of the deck) on the expansion device 3 side from the middle part in the bridge axis direction.

The normal PCa member 5 includes reinforcing bars 9 arranged in two tiers, one above the other, so as to extend in the bridge axis direction and the bridge width direction, and bridge width direction tension members 10 arranged in two tiers, one above the other, 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 in a tensioned state to the concrete portion of the normal PCa member 5.

Each of the inclined PCa members 6 has a hypotenuse 11 that extends 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 PCa member 12 that is arranged closest to the expansion device 3 in the bridge axis direction and to which one end of the diagonal tension member 7 is fixed, one or more intermediate PCa members 13 that are arranged more centrally than the end PCa member 12 in the bridge axis direction, and a fixing PCa member 14 that is arranged most centrally in the bridge axis direction among the inclined PCa members 6 and to which the other end of the diagonal tension member 7 is fixed.

The endmost PCa member 12 has a roughly triangular shape in plan view. This triangular shape is composed of one side along one side edge (the bottom side in Figure 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 tension members are installed during factory fabrication. Depending on the dimensions of the endmost PCa member 12, bridge width direction tension members 10 may be installed in the endmost PCa member 12 during factory fabrication.

The intermediate PCa member 13 is generally trapezoidal 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 tiers, one above the other, so as to extend in the bridge axis direction and the bridge width direction, and bridge width direction tension members 10 arranged in two tiers, one above the other, 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.

The fixing 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 tension members 10 are arranged in the same manner as the normal PCa member 5 and the intermediate PCa member 13.

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 face of the concrete part of the PCa members 5, 6 in the bridge axis direction, and form a loop joint with the reinforcing bars 9 of the other PCa members 5, 6 adjacent in the bridge axis direction. The PCa members 5, 6 have box-punch holes 4 that penetrate in the vertical direction. The box-punch holes 4 receive anti-slip members and are filled with concrete.

The diagonal tension members 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 parallel diagonal tension members 7 are used. The diagonal tension member 7 arranged closest to the expansion device 3 passes through the chamfered portion 15 of the end PCa member 12 and the middle PCa member 13. It is preferable that the diagonal tension members 7 are arranged approximately evenly in the direction perpendicular to the diagonal tension members 7 in the end PCa member 12. One end of the diagonal tension member 7 is fixed to the end PCa member 12 via a fixing device (not shown), and the other end is fixed to the fixing PCa member 14 via a fixing device (not shown). The surfaces on the end PCa member 12 and the fixing PCa member 14 where the diagonal tension members 7 are fixed are constituted by the cutout portion 16 cut perpendicular to the diagonal tension members 7.

The diagonal tension members 7 are arranged in the sheath 17. The sheath 17 includes a portion embedded in the inclined PCa member 6 and a portion embedded in the filling concrete 8. The sheath 17 embedded in the inclined PCa member 6 is arranged between the reinforcing bars 9 and the bridge width direction tension members 10 arranged at the top and the reinforcing bars 9 and the bridge width direction tension members 10 arranged at the bottom. The diagonal tension members 7 and the bridge width direction tension members 10 are made of PC steel bars, PC steel wires, PC steel strands, or fiber-reinforced plastics such as carbon fiber or aramid fiber.

The filler concrete 8 includes end filler concrete 18 that is poured on-site between the expansion device 3 and the inclined PCa member 6, and PCa member filler concrete 19 that is poured on-site between the PCa members 5 and 6.

The construction method of the deck structure 1 will be described. The construction method includes manufacturing the PCa members 5, 6 at a factory, transporting the PCa members 5, 6 to the construction site, placing the PCa members 5, 6 on the main girders 2, placing and tensioning the diagonal tension members 7, and pouring the interfacial concrete 8.

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

At the construction site, workers use a crane or similar to place the PCa members 5 and 6 on the main girder 2. After that, workers weld the anti-slip member to the top surface of the main girder 2 within the box-punch hole 4.

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

Next, the worker places the portion of the sheath 17 that is to be embedded in the filling concrete 19 between the PCa members in the designated position between the inclined PCa members 6.

Next, the worker fills the box-punched holes 4 of the PCa members 5 and 6 with concrete and pours the filler concrete 19 between the PCa members. This embeds the anti-slip member in the concrete in the box-punched holes 4 and in the filler concrete 19 between the PCa members. After the filler concrete 19 between the PCa members hardens, the worker inserts the diagonal tension member 7 into the sheath 17 and tensions the diagonal tension member 7. If the anti-slip member is not in the position where the filler concrete 19 between the PCa members should be poured, it is preferable to fill the box-punched holes 4 with concrete and pour the filler concrete 19 between the PCa members after tensioning the diagonal tension member 7.

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

The effects of deck structure 1 are explained below.

By using multiple inclined PCa members 6 that have oblique sides 11 and extend in the width direction of the bridge, it is possible to place PCa members adjacent to the expansion device 3 that extends diagonally without using PCa members that extend diagonally. In addition, the installation position of each inclined PCa member 6 can be easily grasped based on the extension length of the inclined PCa members 6, making construction management easy.

By using the diagonal tendons 7, prestress can be introduced throughout the entire area adjacent to the expansion device 3, thereby suppressing cracking of the concrete and corrosion of the reinforcing bars 9 caused by the cracking.

Prestress is introduced in the extension direction of the normal PCa member 5, intermediate PCa member 13, and anchoring PCa member 14, which have a longer extension length than the end PCa member 12, by the bridge width direction tension members 10. This prevents cracks from occurring in the normal PCa member 5, intermediate PCa member 13, and anchoring PCa member 14 during erection by a crane. In addition, because the bridge width direction tension members 10 are present even at positions away from the diagonal tension members 7, the occurrence of cracks in the normal PCa member 5, intermediate PCa member 13, and anchoring PCa member 14 and corrosion of the reinforcing bars 9 due to cracks are prevented in the completed deck structure 1.

By providing chamfered portions 15 on the end 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 reinforcing bars 9 can be positioned approximately evenly.

When there is only one main girder 2 supporting the end-most PCa member 12, the end-most PCa member 12 is connected to the adjacent intermediate PCa member 13 before being erected on the main girder 2, so that the end-most 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 end-most PCa member 12, the cast-in-place concrete section 12' is stabilized on the main girder 2 by shoring or the like until it is connected to the intermediate PCa member 13.

When concrete is filled into the box-punched holes 4, and the filler concrete 19 is poured 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 filler concrete 19 between the PCa members.

If the anti-slip member is not located in a position where it can be embedded in the filling concrete 19 between the PCa members, after tensioning the diagonal tension member 7, concrete is filled into the box-punched holes 4 and the filling concrete 19 between the PCa members is poured. Therefore, when tensioning the diagonal tension member 7, the deck structure 1 does not receive a restraining force from the main girder 2.

The deck structure 31 according to the second embodiment will be described with reference to Figure 3. In the description, components common to the first embodiment will be given the same reference numerals and will not be described. The deck structure 31 is disposed on the main girder 2 and is adjacent to an expansion device 3 installed on an abutment that has an oblique angle with respect to the bridge axis direction.

The deck structure 31 comprises a plurality of normal PCa members 5 each having a rectangular shape in plan view, a plurality of inclined PCa members 32 arranged between the expansion device 3 and the normal PCa members 5 and adjacent to the expansion device 3, a diagonal tension member 7 extending along the extension direction of the expansion device 3 in the vicinity of the expansion device 3, a lateral tension member 33 inserted parallel to the bridge width direction on the opposite side of the expansion device 3 in the plurality of inclined PCa members 32, 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.

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 forms 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 on one side of the bridge width direction (lower on the paper in FIG. 3) have a shorter length in the extension direction, and the inclined PCa members 32 arranged on the other side (upper on the paper in FIG. 3) have a longer length in the extension direction. The inclined PCa members 32 include reinforcing bars 9 (see FIG. 2) that extend in two stages, up and down, in the bridge axis direction and approximately 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 that extend in two stages, up and down, in the bridge axis direction.

A shoulder surface 36 is provided at the end of each of the inclined PCa members 32 on the side of the expansion device 3 in the bridge axis direction, and the expansion device 3 is partially supported by the shoulder surface 36. Mortar or end filler concrete 18 (see Figure 1) may be provided between the expansion device 3 and the multiple inclined PCa members 32. It is not necessary to provide a shoulder surface 36 on the inclined PCa members 32.

Each diagonal tension member 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 bridge width direction. The diagonal tension member 7 located closest to the expansion device 3 passes under the shoulder surface 36. In the illustrated example, four diagonal tension members 7 are arranged, and it is preferable that the spacing between these diagonal tension members 7 is approximately equal.

Each of the lateral tension members 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 of the bridge width direction. In the illustrated example, three lateral tension members 33 are arranged, and it is preferable that the spacing between these lateral tension members 33 is approximately equal.

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 extend over substantially the entire length of the bridge width direction, and a plurality of second intermediate tension members 34b that are 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 spacing 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 spacing between these intermediate tension members 34 is substantially uniform.

The sides of the inclined PCa member 32 to which the diagonal tension members 7, lateral tension members 33 and intermediate tension members 34 are fixed have cutout portions 37 having surfaces to which fixing devices (not shown) are fixed perpendicular to the extension direction of each tension member 7, 33 and 34. The portion of the deck structure 31 in the middle in the bridge width direction to which the second intermediate tension member 34b is fixed is a box cutout portion 38. A box cutout portion 39 is also formed in the portion that receives the anti-slip member.

The sides of the inclined PCa members 32 are parallel to each other in the vertical direction and extend generally in the bridge axis direction. However, the end sides of the bridge axis direction of the abutting sides of the adjacent inclined PCa members 32 are formed in a stepped shape. Therefore, the peripheral area through which the diagonal tension members 7 and the intermediate tension members 34 (which are inclined at a relatively large angle to the bridge width direction) arranged on the expansion device 3 side of the intermediate tension members 34 pass, abut against each other on a surface perpendicular to the extension direction of the diagonal tension members 7 and the intermediate tension members 34. Mortar (not shown) or PCa member inter-part concrete 19 may be provided between the adjacent inclined PCa members 32.

The diagonal tendons 7, lateral tendons 33, intermediate tendons 34 and bridge axial 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.

The construction method of the deck structure 31 will be described. The construction method includes manufacturing the normal PCa member 5 and the inclined PCa member 32 (hereinafter, when referring to both the normal PCa member 5 and the inclined PCa member 32, they will be referred to as "PCa members 5, 32") at a factory, transporting the PCa members 5, 32 to the construction site, placing the PCa members 5, 32 on the main girder 2, and placing and tensioning the diagonal tension members 7, lateral tension members 33, and intermediate tension members 34.

The PCa members 5 and 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 tension members 35, place the diagonal direction tension members 7, the lateral direction tension members 33, and the sheaths 17 (see FIG. 2) for the intermediate tension members 34, install a formwork (not shown), pour concrete into the formwork while applying tension to the bridge axis direction tension members 35, and remove the formwork after the concrete hardens. The tension of the bridge axis direction tension members 35 may be introduced by a post-tensioning method instead of a pre-tensioning method. After curing, the PCa members 5 and 32 are transported to the construction site.

At the construction site, workers use a crane or similar 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.

The effects of the deck structure 31 are explained below.

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 area adjacent to the expansion device 3 that extends in the diagonal direction without using PCa members that extend in the diagonal direction. In addition, there is no need to provide a relatively small PCa member like the end-most PCa member 12 in the first embodiment (see Figure 1), which improves construction efficiency.

By using the diagonal tendons 7 to introduce prestress to the entire area adjacent to the expansion device 3, cracking of the concrete near the expansion device 3 and corrosion of the reinforcing bars 9 caused by the cracking are suppressed. Furthermore, by using the lateral tendons 33 and intermediate tendons 34 to introduce prestress to the area away from the expansion device 3, cracking of the concrete in the area away from the expansion device 3 and corrosion of the reinforcing bars 9 caused by the cracking are suppressed.

Prestress is introduced by the bridge axial tension members 35 in the extension direction of the inclined PCa member 32, which prevents cracks from occurring in the inclined PCa member 32 during erection by a crane.

The sides of the inclined PCa members 32 that come into contact with each other are partially stepped, so that the prestress from the diagonal tension members 7 and the intermediate tension members 34, which have a relatively large inclination from the bridge width direction, is efficiently transmitted between the inclined PCa members 32.

This concludes the explanation of the specific embodiment, but the present invention is not limited to the above embodiment or modified example, and can be modified in a wide range of ways. The number 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.

Reference Signs List 1, 31: Precast prestressed concrete deck structure 2: Main girder 3: Expansion device 6, 32: Inclined PCa member 7: Diagonal tension member 10: Bridge width direction tension member 11: Hypothetical side 12: Endmost PCa member 12': Cast-in-place concrete portion 13: Intermediate PCa member 14: Anchoring PCa member 15: Chamfered portion 19: Filling concrete between PCa members 33: Lateral tension member 34: Intermediate tension member 35: Bridge axis direction tension member

Claims (13)

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 tension member extending in the extension direction of the expansion device and inserted into all of the inclined portion precast concrete members in the vicinity of the expansion device, the diagonal tension member being inserted into all of the inclined portion precast concrete members in the extension direction of the expansion device, the diagonal tension member being inserted into all of the inclined portion precast concrete members in the vicinity of the expansion device, the diagonal tension member being inserted into all of the inclined portion precast concrete members in the extension direction of the expansion device, the diagonal 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. 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. The precast prestressed concrete deck structure according to claim 3, wherein the corners of the end precast concrete member and the intermediate precast concrete member formed by the oblique side and the side extending in the bridge width direction in plan view, where the extension lines of both sides intersect at an acute angle, form a chamfered portion with a chamfered shape at a surface intersecting the bridge width direction, and one of the diagonal tension members passes through the chamfered portion. 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. The precast prestressed concrete deck structure according to claim 5, wherein each of the inclined precast concrete members includes a bridge axial direction tension member extending in the bridge axial direction. 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;
7. The precast prestressed concrete deck structure according to claim 5 or 6, further comprising an intermediate tension member arranged between the diagonal tension member and the lateral tension member in the bridge axis direction and inclined at an angle smaller than that of the diagonal tension member with respect to the bridge width direction. 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 an extension direction length shorter than the extension direction length of the first inclined portion precast concrete members,
8. The precast prestressed concrete deck structure according to 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. 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 section of the inclined portion so as to extend parallel to the extension direction of the expansion device and pass through all of the precast concrete section of the inclined portion;
and tensioning the diagonal tendons. 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. 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. 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. 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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