JP2006283317A - Prestressed concrete floor slab formed of precast concrete plates, and method of constructing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of constructing a PC floor slab, according to which precast concrete plates are continuously arranged in one body without joints therebetween, to thereby construct the PC floor slab excellent in load-bearing properties and applicable to a quay or a runway on which an extremely heavy weight is partially imposed. <P>SOLUTION: Each precast concrete plate 1 having a rectangular shape, has prestressing tendon insertion holes formed therein at diagonal locations, and a number of the precast concrete plates 1 thus formed are longitudinally and transversely arranged such that two longitudinal sides are supported, to thereby form the floor slab. Then each continuous PC tendon 30 is inserted into the plurality of PC tendon insertion holes formed in the respective precast concrete plates 1 adjacent to each other in diagonal directions, and both ends of the tendon are strained and anchored to both side ends of the floor plates, to thereby apply prestressing in the diagonal directions to the respective precast concrete plates 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a prestressed concrete floor plate (hereinafter referred to as PC) using a precast concrete plate that is constructed using a precast concrete plate, which is constructed by using a precast concrete plate to support a substructure and use it as a runway etc. And a construction method thereof.

  In general, when building floorboards such as jetty or aircraft runway constructed on the water, precast concrete plates are placed side by side on the floorboard support frame supported by pillars such as piles, and the surface is the road surface for running Or asphalt pavement on the road surface. In this case, it is advantageous in terms of weight and load resistance to use a square prestressed concrete plate as the precast concrete plate.

  Moreover, when a concrete floor board is constituted by arranging precast concrete plates, as a method of integrating the whole floor board and applying continuous prestress to it, straddling each precast concrete plate in the width direction and the longitudinal direction of the floor board respectively. A method of inserting a PC tendon and fixing the tension for each unit length is common.

  When building a long concrete floor slab by arranging conventional precast concrete plates side by side and inserting prestressed PC tension members in the vertical and horizontal directions across these, use a square precast concrete plate, If the four sides are supported by the lower beam, the bending moment generated by the load acting on the surface of the precast concrete plate will be the same in the vertical and horizontal directions, so it is necessary to apply the same prestress in the vertical and horizontal directions. Arise.

  However, the length at which prestressing can be applied at a time is limited by the conditions of the weight of the precast concrete plate and the equipment for applying tension, such as an airport runway, which is several hundred meters wide and long. When a roadbed with a length of several kilometers is formed, prestressing work in the width direction of the roadbed can be performed outside the formed roadbed, but prestressing work in the length direction is performed within the formed roadbed. It is necessary to secure a space for every certain length.

  That is, as shown in FIG. 13, a PC tension member 53 is inserted continuously in a plurality of precast concrete plates 50, 50, and work for fixing the tension member of the PC tension member 53 every certain length of, for example, about 100 m. A space 54 is required, and it is necessary to fill the space 54 with cast-in concrete 55 as shown in FIG.

  In addition, since it is difficult to introduce prestress in this part, it must be made of reinforced concrete, and since this part becomes an expansion joint, there is a step, and the pavement 51 above it is cracked. There is a problem that the driving performance is impaired.

  In addition, in the case of the conventional precast concrete plate as described above, for example, when used in a place where an extremely heavy load of 600 tons is applied locally, such as an airport runway, an aircraft passage, or a gantry crane passage at a wharf. In order to obtain sufficient load resistance, the overall plate thickness must be increased and a large prestress must be introduced over the entire plane, and the weight of the precast concrete slab itself is extremely large. In addition, there is a problem that manufacturing is difficult, and it requires high technology, many materials such as PC tendons and concrete, and advanced equipment for introducing prestress, which inevitably leads to high costs. When using a square precast concrete plate, there is a limit to the size when road transportation is required. If there is a problem that can not be road transport of a large size, such as 10m square.

  In addition, when a precast concrete plate with a large area is used in a place where a heavy load is applied locally, if the local load acts on a part that is biased from the center, the plate itself will warp and the corners will rise. Each time an aircraft or crane passes, the support part floats and vibrates, resulting in a step between adjacent plates. To prevent this, the four corners of the precast concrete plate and the lower support below it There is a problem that it is necessary to strengthen the connection with the structure, and for that purpose, high technology and expensive materials are required.

  In view of the conventional problems as described above, the present invention can integrate a continuous floor plate having a long length of several thousand meters and a total width of several hundred meters with a precast concrete plate continuously without joints, The purpose of the present invention is to provide a PC floor board using a precast concrete slab excellent in load resistance that can be used as a wharf or runway that is locally heavy, and a construction method thereof.

  In order to solve the conventional problems as described above and achieve the intended purpose, the feature of the invention described in claim 1 is that a diagonal shape of the rectangular precast concrete plate is diagonally oriented. Direction PC tension material insertion holes and short side direction PC tension material insertion holes oriented in the short side direction at predetermined intervals in at least the central region of the rectangle, respectively, and around the four sides of the precast concrete plate The floor plate is formed by arranging a large number of front and rear, left and right sides while supporting at least two of the long sides, and diagonal PC tension members are inserted through a plurality of precast concrete plates adjacent in both diagonal directions. A continuous diagonal PC tension member straddling the hole is inserted, and the short side direction PC tension member insertion hole is extended across the precast concrete plate adjacent to the short side direction. Is inserted in the width direction PC tendon was there both ends of each PC tendon in prestressed concrete floor using precast concrete plate comprising a feature that is stressing anchorage on both sides of the floor plate.

Further, the invention according to claim 2 is characterized in that, in addition to the configuration of claim 1, the joint PC tension member oriented in the short side direction in joint concrete between the precast concrete plates adjacent in the longitudinal direction. The pre-stress in the short side direction is applied to the joint concrete.
The feature of the invention described in claim 3 is that a diagonal PC tension member insertion hole directed diagonally to both diagonal positions of the rectangular precast concrete plate, and at least a central region of the rectangle are spaced apart from each other by a predetermined interval. By forming a short side PC tension material insertion hole directed in the short side direction and arranging a large number of the precast concrete plates side by side in the front, back, left and right directions with the bottom surfaces of the two long sides supported A floor board is formed, and a diagonal PC tension member that is continuous across the diagonal PC tension material insertion holes of a plurality of precast concrete plates adjacent to each other in both diagonal directions is inserted, and adjacent to the short side direction. The PC tension material in the width direction continuous with the short side direction PC tension material insertion hole is inserted across the precast concrete plate, and both ends of each PC tension material are tightened on both sides of the floor board. In the construction of the fixed prestressed concrete floor board, the diagonal PC tension member is arranged on a part of the length of the floor board formed in a predetermined length by arranging the precast concrete plates in the front, rear, left, and right directions over the entire width of the floor board. Each diagonal PC tension member straddling between the precast concrete slabs on both sides, leaving a shrinkage-absorbing part that does not impart any prestress in both diagonal directions due to the tension is fixed, and prestress is introduced. After the elapse of a period of time, the prestressed concrete floor board using a precast concrete plate that integrates the shrinkage absorbing portion and the pre-tensioned portions on both sides thereof by fixing both diagonal PC tension members straddling both Is in the construction method.

  Further, the invention according to claim 4 is characterized in that, in addition to the structure of claim 3, the joint PC tension member oriented in the short side direction in the joint concrete between the precast concrete plates adjacent in the longitudinal direction. Is inserted, and prestressing in the short side direction is introduced into the joint concrete by tensioning the PC tendon.

  Further, the invention according to claim 5 is characterized in that, in addition to the structure of claim 3 or 4, the precast concrete slab is pre-stressed in the diagonal direction.

  In the present invention, the diagonal PC tension material insertion holes directed diagonally to the diagonal positions of the rectangular precast concrete plate are directed in the short side direction at a predetermined interval in at least the central region of the rectangle. Each of the short side direction PC tension material insertion holes is formed, and a large number of the precast concrete plates are arranged side by side in the front, rear, left and right directions with at least two of the four sides around the precast concrete plate supported. To form a floor board, and insert a diagonal PC tension material continuous across the diagonal PC tension material insertion holes of a plurality of precast concrete plates adjacent in both diagonal directions, and adjacent to the short side direction. A width direction PC tension material that is continuous with the short side direction PC tension material insertion hole is inserted across the precast concrete plate to be fitted, and both ends of each PC tension material are both sides of the floor plate. Since the precast concrete plate to be used is rectangular and has a structure that supports the two sides on the long side, the bending moment generated in the precast concrete plate to be used is larger than that in the long side direction. Since the short side direction is large, that is, the dominant direction of the bending moment is the short side direction, almost all of the prestress to counter the bending moment by the PC tension material in the short side direction should be taken. When a long roadbed such as a runway is constructed, it is only necessary to apply a large amount of prestress in the width direction having a relatively short length, and sufficient prestress can be applied with good workability.

  Further, the prestress in the long side direction is given by an oblique tension force caused by the PC tendon inserted across the diagonal direction. Since the bending moment of the precast concrete plate is small in the long side direction, a sufficiently large size can be easily imparted by this prestress in the oblique direction. At the same time, since a precast concrete plate having a small width and a long length can be used, road transportation is possible even for a large one, and a high-quality precast concrete plate manufactured in a factory can be used.

  Furthermore, the prestressing operation in the oblique direction can be performed outside the side edge of the PC floor plate to be constructed, and can be constructed without providing a work space in the road bed when creating a road bed such as a runway. It is possible to create a long and uniform PC floor plate that is homogeneously continuous.

  Further, by inserting a joint PC tension material in the short side direction into the joint concrete between the precast concrete plates adjacent to each other in the longitudinal direction, and applying prestress in the short side direction to the joint concrete, The whole floorboard including joint concrete becomes prestressed and concrete structure.

  Further, in the construction of the PC floor board, the precast concrete plates are arranged in the longitudinal direction of a part of the floor board formed in a predetermined length by arranging the precast concrete plates in the front, rear, left, and right directions, and the diagonal PC tension material over the entire width of the floor board. Prestress is introduced by fixing the PC tension members straddling between the precast concrete slabs on both sides, leaving a shrinkage absorbing portion that does not give any prestress in both diagonal directions, and a certain period of time has passed Then, the shrink-absorbing portion and the tip tension portions on both sides thereof are integrated by fixing both diagonal PC tension members straddling both, thereby drying the concrete of the precast concrete plate of the tip tension portion. The contraction is absorbed by the contraction absorbing part, and the joint interval in the contraction absorbing part is expanded by the contraction of the tip tension part. By mortar filled to integrate contraction absorbing portion can be made small movement due completed PC floorboards across the concrete drying shrinkage.

  Furthermore, by using precast concrete plates that have been prestressed in the diagonal direction in advance, the load-bearing capacity of the precast concrete plates themselves is increased, and the prestressed concrete plates straddle multiple precast concrete plates. Even before the introduction, the vehicle and the work machine can be run on the precast concrete plates installed side by side, and the workability of the floorboard construction is improved.

  Next, embodiments of the present invention will be described based on examples shown in the drawings.

  1 to 5 show an example of a precast concrete plate used in the present invention. This precast concrete plate 1 has a rectangular shape, and the short side of the rectangle is formed at a ratio of about ½ of the long side. As an example, the long side is about 8 m and the short side is about 4 m. On the bottom surface of the precast concrete plate 1, diagonal ridges 2 and 2 are formed so as to cross each other at both diagonal positions, and the peripheral ridges 3 are integrally formed on the lower surface of the peripheral edge in a frame shape. Molded.

  The four corners of the precast concrete plate 1 are formed with notches 4, 4... For fixing the ends of the PC tendon material, and each notch 4 has an angle perpendicular to the diagonal line of the precast concrete plate body. The holding surface 4a is formed, and the supporting plates 5 and 5 are embedded in the fixing surface 4a, and the end portions of the PC tension members 6 that are inserted into the supporting plate 5 in the diagonal direction of the precast concrete plate 1 and are tensioned are provided. It has been established. The PC tension member 6 is inserted in an arrangement close to the upper surface side at the corner of the precast concrete plate 1 and closer to the lower surface side of the diagonal ridge 2 at the center portion, and the upward component force at the center portion due to the tension, that is, It is installed so that the lift works.

  In addition, the prestress is introduced by the PC tension material 6 by applying a desired prestress in advance by a pretension method or a post tension method in a precast concrete plate production yard. For example, after construction, even before the final pre-stress is introduced, the work vehicle and heavy equipment can run.

  In the precast concrete plate 1, diagonal PC tension material insertion holes 7 that are opened through the fixing surface 4 a of the notch portion 4 toward the respective diagonal directions at positions close to the bottom surface of the diagonal ridge portion 2. , 7 are formed, and in the central portion in the longitudinal direction, a short side penetrating and opening on both sides toward the short side direction, that is, the precast concrete plate width direction, is located close to the top surface of the precast concrete plate 1. A number of directional PC tendon insertion holes 8, 8... Are formed.

  In this embodiment, the short side direction PC tension material insertion holes 8, 8,... Are centered on the central portion in the long side direction of the precast concrete slab 1, and the entire area is in a range of about ½ of the long side length. Although it is provided at regular intervals, it may be provided over the entire length in the long side direction of the precast concrete plate.

  These PC tendon insertion holes 7 and 8 are formed, for example, by embedding a PC tendon insert sheath (sheath tube) such as a spiral wound tube when the precast concrete plate 1 is cast into concrete.

  Next, the work process at the time of construction of the PC floor board using the above-mentioned precast concrete plate 1 will be described.

1. Substructure and precast concrete slab temporary construction For example, a substructure 10 for floor plank support is constructed on a pillar such as a pile that is erected while being supported on a submerged ground or the like, as shown in FIGS. The undercarriage 10 is constructed with parallel girders 10a, 10a... For supporting the lower surfaces of the two long sides of the precast concrete plate 1 on the upper surface, and the adjacent precast concrete plates 1 are placed on the girders 10a, 10a. Install the heels 11, 11 ... to support them together. The ridge 11 uses a structure capable of adjusting the height between the precast concrete plates described later. The precast concrete slabs 1, 1,. At this time, the interval of the width direction joint 12 between the adjacent sides between the precast concrete slabs 1 and 1 adjacent to each other in the longitudinal direction is opened by about 150 mm.

  In this embodiment, the two long sides of the rectangular precast concrete slab 1 are supported by a so-called two-side support structure in which the substructure 10 has a so-called two-side support structure. The structure to support may be sufficient.

Of 2. Height adjustment work After temporary construction, height adjustment between adjacent precast concrete slabs 1 and 1 is performed. As shown in FIG. 8 (a), the pad 11 is housed in a steel mortar receiving box 15 with a plate-like pad 17 supported by a coil spring 16 on its bottom surface and biased upward. When adjusting the height, the step-adjusting metal fitting 18 is placed between the precast concrete plates 1 and 1 and fixed to the precast concrete plate 1 with bolts 19. The bolt 19 is screwed into an anchor nut 20 that has been previously installed. Thereby, the height between the precast concrete plates 1 and 1 is made uniform. At this time, the gap between the upper surface of the substructure 10 and the bottom surface of the precast concrete plate 1 varies due to variations in the mounting height of each of the flanges 11, 11. The coil spring 16 is pressed against the bottom surface of the precast concrete plate 1. In this state, the flatness is adjusted using a height adjusting tool such as a hydraulic jack. After adjusting the height in this way, as shown in FIG. 8 (b), the mortar receiving box 15 is filled with a non-shrinkable mortar 21, and the lower side of the pad 17 is filled. Fix the height of the ridge 11.

  As described above, by configuring the flange 11, the height of the flange 11 after height adjustment is automatically adjusted by the elasticity of the coil spring 16, and the height fills the mortar receiving box 15 with mortar. It will be fixed only by it, and the adjustment of the support structure of the back surface after height adjustment can be performed easily.

3. Diagonal direction PC tension material continuous insertion work As shown in FIG. 9, the PC tension material insertion holes 7, 7... Of the precast concrete plates 1, 1. The PC tendon 30 is continuously inserted. For example, as shown in FIG. 10, an individual PC tendon 30a is inserted into each precast concrete plate 1 and is connected by a coupler 30b in a space 31 between the precast concrete plates in the diagonal direction.

  In this way, by inserting the individual PC tendons 30a into each precast concrete plate 1 in a state where both ends protrude, the PC tendon insertion work in the field is simplified and each precast concrete plate is also inserted. In the case where the PC tendon insertion hole 7 is curved in the vertical and horizontal directions, the PC tendon 30 can be continuously inserted only by connecting the individual PC tendons 30a.

  In addition, after using the precast concrete slab 1 in which the PC tension material for continuous use is not inserted, and adjusting the height described above, the PC tension material 30 of the required length is inserted into each PC tension material insertion hole 7, 7. ... may be inserted across.

  In any case, in the space portion 31 constituted by the cutout shape of the four corners of each precast concrete plate 1, the PC tendon 30 is inserted into the cable duct 32a. In this case, in the system using the coupler 30b, for example, a telescopic sheath or a half-shaped sheath is used as the cable duct.

4). Continuous insertion of width direction PC tendon As shown in FIGS. 9 and 11, precast adjacent to each other between the long sides of the precast concrete plates 1 and 1 installed side by side, that is, the long side joint 33 on the beam 10a. A cable duct 32b is installed across the short side direction PC tension material insertion holes 8 and 8 of the concrete plate 1, and a plurality of precast concrete plates 1, 1... Arranged in the width direction through the cable duct 32b. Then, the width direction PC tendon 34 is inserted.

  The insertion of the PC tendon 34 may be performed after filling the joint mortar described later into the joint 33 between the long sides with the cable duct 32b described above installed. In addition, a single PC tension member 34 may be inserted across the entire width of the PC floor plate to be tensioned at one time, or a plurality of PC tension members may be connected by a coupler.

5. Joint work Precast concrete slabs 1, 1, ... Install cable ducts 32a and 32b across the precast concrete slabs 1, 1 After installing the joint sheath 36 in the width direction, the non-shrinkable joint mortar is placed in the joints 12 and 33 in the long side direction and the short side direction between the precast concrete plates and the space 31 in the diagonal direction. Fill.

6). Insertion of Joint PC Tension Material After filling the mortar by the joint work described above, the joint PC tension member 38 is inserted into the joint sheath 36 embedded in the joint in the short side direction, after the mortar is solidified. The joint PC tension member 38 may be inserted before filling the joint mortar.

7). PC tension material tension work After the joint mortar is solidified, tension of each PC tension material 30, 34, 38 is performed. In this tensioning operation, one end of each PC tension member is fixed to one edge of the PC floor board to be constructed, and the tension is fixed using a hydraulic jack at the other edge.

  The order of tension of the PC tension members 30, 34, 38 is such that the diagonal PC tension members 30 are first tensioned, and then the tension work of the PC tension members 34, 38 in the width direction is performed. As a result, the precast concrete slabs 1, 1... Are integrated, and at the same time, prestresses in the width direction and the diagonal direction in each precast concrete slab 1 are introduced.

  In addition, while the tension | tensile_strength by the diagonal direction PC tension | tensile_strength material 30 is mainly for performing integration of the longitudinal direction between each precast concrete slab 1,1, by the component force of the short side direction of the precast concrete slab, Assist in introducing prestress in the width direction.

  In addition, prestress in the width direction is introduced into the precast concrete plate 1 by the short side direction PC tension material 34, and prestress in the width direction of the PC floor board is applied to the joint in the short side direction by the joint portion PC tension material 38. Let it be introduced.

  Moreover, this PC tension material tensioner is a shrinkage absorbing part for absorbing the drying shrinkage of concrete at a certain interval, for example, every 300 m to 600 m, in a part of the longitudinal direction when the total length of the floor board to be constructed is long. And fix the tension of the PC tension material in this part over time. This shrinkage absorbing portion constitutes a portion where no prestress is applied over the entire width of the floor board. For example, as shown in FIG. 12, diagonal PC tension members 30s, 30s intersecting each other as shown in FIG. In addition, the pre-stressed portions S and S are prestressed by fixing the tension material of the width direction PC tension material, and the contraction absorbing portion N in which the PC tension material in any direction is not tensioned is provided therebetween. The pre-tension part S includes a semi-tension part S1 that is tensioned only in one diagonal direction, and a total tension part S2 that is tensioned in both diagonal directions.

  In FIG. 12, the PC tendon 30s drawn with a solid line shows a tensioned one, and the PC tendon 30n shown with a broken line shows an untensioned one.

  In this way, prestress is first introduced to both sides of the shrinkage absorbing portion N, and an allowable period is allowed to elapse. As a result, the concrete drying shrinkage of each precast concrete plate 1 proceeds, the end portion of the first tension portion S moves, and the joint interval between the shrinkage absorbing portion N increases.

  After the spread joint is filled with non-shrinkable joint mortar, prestress is introduced into the shrinkage absorbing portion N and integrated with the tip tension portions S on both sides thereof. This operation is performed by tension-fixing the diagonal PC tension members 30n and 30n inserted across the half-tip tension part S1 and the contraction absorption part N described above.

  Each of the PC tendons 30s and 30n may be one having a length extending over the entire length of both side portions of the floor plate, or one having a desired length connected by a coupler.

8). Grout Work After tensioning each PC tendon 30, 34, 38 and introducing prestress, grout is injected into each PC tendon insertion hole and cable duct.

9. Surface pavement Pavement is carried out by laying a pavement such as asphalt on the PC floor board formed in this way as necessary. This pavement is not always necessary.

It is a top view of an example of the precast concrete board used for the method of the present invention. It is a front view same as the above. It is a bottom view same as the above. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line. It is a top view which shows the precast concrete plate installation state in the method in this invention. It is the same side view. It is sectional drawing which shows a height adjustment process same as the above. It is a partial enlarged plan view which shows the outline of the tension | tensile_strength fixing state of PC tension material in this invention. It is a partial enlarged plan view which shows a diagonal direction PC tendon connection part same as the above. It is an expanded sectional view which shows the joint part insertion state of the width direction PC tendon same as the above. It is a schematic top view which shows the state which provided the shrinkage | contraction absorption part in the tension fixing operation | work of the PC tendon material in this invention. It is a top view which shows the further another example of the floor board by the conventional precast concrete board. It is sectional drawing which shows the joint part same as the above.

Explanation of symbols

N contraction absorption part S point tension part S1 half tension part S2 full tension part 1 precast concrete plate 2 diagonal ridge 3 circumferential ridge 4 notch 4a fixing surface 5 bearing plate 6 PC tension material 7 diagonal PC tension Material insertion hole 8 Short side direction PC tension material insertion hole 10 Substructure 10a Girder 11 １２ 12 Width direction joint 15 Mortar receiving box 16 Coil spring 17 Pad 18 Step adjustment metal fitting 19 Bolt 20 Anchor nut 21 Non-shrinkable mortar 30 Diagonal PC tension 30a Individual PC tension 30b Coupler 30s Tensioned PC tension 30n Untensioned PC tension 31 Space 32a, 32b Cable duct 33 Long side joint 34 Width PC tension 36 Joint sheath 38 Joint PC tendon

Claims (5)

Diagonal direction PC tension material insertion hole directed diagonally to both diagonal positions of a rectangular precast concrete plate, and short side direction PC oriented in the short side direction with a predetermined interval at least in the central region of the rectangle Each of the tension material insertion holes is formed,
A plurality of precast concrete plates adjacent to each other in both diagonal directions are formed by arranging a large number of the front and rear, left and right side by side in a state where at least two of the four sides around the precast concrete plate are supported. While inserting the diagonal PC tension material that is continuous across the diagonal PC tension material insertion hole,
The width direction PC tension material is inserted through the width direction PC tension material insertion hole across the precast concrete plate adjacent in the short side direction, and both ends of each PC tension material are fixed at both sides of the floor board. Prestressed concrete slab using precast concrete slab characterized by having been made.   2. The joint PC tension member directed in the short side direction is inserted into joint joint between the precast concrete plates adjacent in the longitudinal direction, and pre-stress in the short side direction is applied to the joint concrete. Prestressed concrete floor board using precast concrete slab. Diagonal direction PC tension material insertion hole directed diagonally to both diagonal positions of a rectangular precast concrete plate, and short side direction PC oriented in the short side direction with a predetermined interval at least in the central region of the rectangle Tensile material insertion holes are formed respectively, and a floor board is formed by arranging a large number of the precast concrete plates side by side in the front, rear, left and right directions while supporting the bottom surfaces of the two long sides, and adjacent to each other in both diagonal directions. While inserting the diagonal PC tension material which continued across the diagonal PC tension material insertion hole of a plurality of precast concrete plates, and straddling the precast concrete plate adjacent to the short side direction, the short side Pre-stressed control in which a width direction PC tension material is inserted into the direction PC tension material insertion hole, and both ends of each PC tension material are fixed in tension on both sides of the floor board Upon construction of the REIT floorboards,
The pre-cast concrete plates are arranged in a longitudinal direction on a part of the floor plate formed in a predetermined length by arranging the pre-cast concrete slabs, and any pre-stress in both diagonal directions by the diagonal PC tendon is applied over the entire width of the floor plate. The pre-stress is introduced by fixing the diagonal PC tension members straddling between the precast concrete slabs on both sides while leaving the shrinkage absorbing portion not applied, and after a certain period of time, the shrinkage absorption A method for constructing a prestressed concrete floor board using a precast concrete slab that unites a part and a tip tension part on both sides thereof by fixing and fixing both diagonal PC tension members straddling both parts.   A joint PC tension member oriented in the short side direction is inserted into the joint concrete between the precast concrete plates adjacent in the longitudinal direction, and the short side direction is inserted into the joint concrete by tensioning the PC tension member. A prestressed concrete floor board using the precast concrete slab according to claim 3, wherein prestressing toward the surface is introduced.     The construction method of the prestressed concrete floor board using the precast concrete plate of Claim 3 or 4 using what prestress is previously given to the diagonal direction as a precast concrete plate.

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