JP5703159B2 - Precast prestressed concrete beam - Google Patents

Description

  The present invention relates to a precast prestressed concrete beam formed by joining a plurality of members divided in the axial direction.

  Reinforced concrete structures often employ a rigid frame structure with a rigid connection between the column and the beam. Conventionally, the concrete in the column joint and the beam concrete are cast at the same time. It was often built with. In recent years, for the purpose of shortening the construction period and reducing costs, a method has been developed in which columns and beams are manufactured as precast concrete in the factory, and the manufactured components are assembled on-site to construct a ramen frame. .

  The precast structural member is transported from the factory to the construction site by a trailer or the like, and is arranged at a predetermined position by a lifting machine such as a tower crane. Therefore, there are certain restrictions on the length and weight of the member. For example, by introducing pre-stress, the beam member can increase the axial length while suppressing an increase in weight, but in reality it is difficult to transport from the factory to the site. There is a limit to lengthening the member length.

  By the way, when prestress is introduced into the beam, in order to effectively improve the bending strength, a tension material such as a PC steel wire is often arranged in a curved shape. However, such an arrangement of the tendon requires a jig for positioning the sheath tube, and takes a lot of labor for installation. In addition, pre-stress is usually post-tensioned after it is mounted on a pillar, so work such as tension and grout injection when pre-stress is introduced and its management tend to be complicated, and installation is very difficult. Takes a lot of effort and time.

  As an invention that can solve such a problem, a precast concrete beam is divided into a pair of end pieces and a center piece, and a tension material is linearly arranged on the upper end side of the end piece, and a lower end is placed on the center piece. It is assumed that the tension material is arranged linearly on the side and is manufactured in advance as a pre-tensioned precast prestressed concrete (hereinafter referred to as PCaPC) member, and in the field, the central piece is arranged between the end pieces. In this state, the main bars protruding from the joint end faces facing each other are overlapped, and the cast-in-place concrete is placed at the joint between the center piece and the end piece, so that these pieces are integrated. An invention has been proposed (see Patent Document 1). According to the present invention, it is possible to facilitate the manufacture of each piece by arranging the pretensioning tension material in a straight line, and to simplify the construction and shorten the construction period by eliminating the introduction of prestress at the site. is there.

JP 2009-150115 A

  However, in the invention of Patent Document 1, since cast-in-place concrete is used at the joint between the pieces, formwork assembly, rebar assembly, concrete placement, curing, etc. are required for this purpose, and further improvement in shortening the work period is required. There was room.

  The present invention has been made in view of such a background, and facilitates manufacture and transportation of a precast product to the site, and also facilitates assembly and installation work at the site, thereby shortening the construction period. Its main purpose is to provide precast prestressed concrete beams.

  In order to solve the above problems, the present invention is a precast prestressed concrete beam (10) composed of three pieces divided in the axial direction and spanned between a pair of columns (2, 2), The two end pieces (11) arranged at the end portions in the direction are respectively formed with the joint portion (2a) of the column integrally formed at one end, the main bar (25) extending in the axial direction, and the upper portion A central piece (12) having a pretension tension member (27) arranged in the axial direction and a central piece (35) extending in the axial direction and a pretension tension arranged in the lower part. A main bar of the end piece and a main bar of the central piece are joined to each other by a reinforcing bar joining means (40), so that the end piece and the central piece are directly connected to each other. To be joined to To. Here, the direct joining means joining without using cast-in-place concrete at the joint, using only a joint material for filling a gap such as grout, or without using anything.

  Such a configuration facilitates the manufacture of the end piece and the central piece, facilitates the transport to the site, and allows the pieces to be connected to each other without using the cast-in-place concrete when joining the pieces at the site. Can be joined directly, so that assembly and installation work can be facilitated and the construction period can be shortened.

  Moreover, according to one aspect of the present invention, the number of main bars of the end piece is larger than the number of main bars of the central piece, and the reinforcing bar joining means is installed according to the number of main bars of the central piece. It can be configured. According to this configuration, it is possible to optimally arrange the main bars for the end piece and the center piece, and at the joint, it is necessary to join the main bars according to the number of center pieces on the side where the number is small It is possible to secure a sufficient bending strength and shear strength and to facilitate the construction. Moreover, since it becomes easy to secure the installation space for the reinforcing bar joining means, it is possible to reduce the cross section of the beam at the joint.

According to another aspect of the present invention, the reinforcing bar joining means includes a sleeve member (41) and a grout (4 2 ) filled in the sleeve member in a state where the main reinforcing bar is inserted into the sleeve member. In one of the central piece and the end piece (11), the main bar (25) is arranged so as to extend from the joint end surface (11a), and the central piece and the end portion In the other (12) with the piece, the sleeve member may be embedded so as to face the joining end surface (12a). According to this configuration, the pieces can be moved in the axial direction, and the main bars extending from one joint end face can be inserted into the sleeve member facing the other joint end face so that the main bars can be joined easily and reliably. .

  According to another aspect of the present invention, the end piece is formed such that its height gradually decreases from the mouthpiece side toward the central piece side, and the central piece is the end piece. It can be set as the structure formed so that it may have the same height as this joining end surface. In commercial buildings such as office buildings, many ducts and piping for air conditioning, water supply / drainage, power supply, etc. are often installed behind the ceiling. Therefore, by adopting such a configuration, it is possible to secure these installation spaces below the central piece without reducing the ceiling height.

According to another aspect of the present invention, the end piece includes an upper flange portion (21), a lower flange portion (2 2 ), and a web portion connecting the upper flange portion and the lower flange portion. (23), and the web portion is formed such that its height gradually decreases from the joint portion side toward the central piece side, and the lower flange portion is connected to the joint portion. The portion (11b) may be formed wider than the upper flange, and may be formed so that the width gradually decreases from the joint portion side toward the central piece side. According to this configuration, it is possible to secure the installation space for the piping under the precast prestressed beam, and to effectively increase the cross-sectional secondary moment at the joint with the joint where the bending stress is the largest, It is possible to reduce the weight of the beam or increase the design load capacity.

  As described above, according to the present invention, precast can be easily manufactured, and can be easily carried into the site and lifted, and can be easily assembled and installed on site, thereby shortening the construction period. Prestressed concrete beams can be provided.

The schematic plan view which shows the frame structure of the building which concerns on this invention II-II sectional view in FIG. Plan view of the PCaPC beam shown in FIG. IV-IV sectional view in FIG. VV sectional view in FIG. VI-VI cross section in Fig. 3 Reinforcement diagram shown along section VII-VII in FIG. Explanatory drawing of assembly and installation procedure of PCaPC beam according to the present invention Explanatory drawing of assembly and installation procedure of PCaPC beam according to the present invention

  Hereinafter, an embodiment in which a precast prestressed concrete beam (hereinafter simply referred to as a PCaPC beam 10) according to the present invention is applied to a frame structure 1 of a multi-layer building such as an office building will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a frame structure 1 on one floor that is a reference floor of a building, and hatching is omitted. In order to avoid complication of the figure, hatching is omitted in other figures as necessary.

  As shown in FIG. 1, a frame structure 1 includes a plurality of columns 2 arranged in a rectangular shape with a predetermined interval in a beam-to-beam direction and a row direction, and a pair of adjacent ones extending in the row direction along the outer periphery of a building. The beam 3 connecting the two pillars 2 and the beam 4 extending along the outer periphery of the building, and extending in the beam direction inside the outer periphery of the building and the beam 4 connecting the adjacent pair of columns 2. And a beam 5 for connecting a pair of opposing columns 2. Note that the frame structure 1 may further include a frame connected to the outside, as indicated by an imaginary line in FIG. Further, the frame structure 1 may include a wall surface structure or a wall brace that is arranged on the outer periphery of the building and functions as a load-bearing wall.

  These columns 2 and beams 3, 4, and 5 are constructed by joining members made of precast concrete. Here, four columns 2 are arranged in two columns in the beam-to-beam direction and six columns are arranged in two columns in the column-row direction, and the beam 5 is formed longer than the beam 4, and the three spans of the beam 4 are opposed to each other as one span. By spanning between the pair of pillars 2, a wide space without an inner pillar is formed inside the frame structure 1.

  As shown in FIGS. 2 and 3, the long beam 5 is formed by joining three pieces (a pair of end pieces 11 and a central piece 12) divided in the axial direction (inter-beam direction) to each other at a joint 13. The PCaPC beam 10 is used. The PCaPC beam 10 is bridged on the PCa pillar piece 50 constituting the pillar 2 on the current floor, and the PCa pillar piece 50 constituting the pillar 2 on the upper floor is further placed thereon, and both ends are fixed. .

  The two end pieces 11 arranged at the axial ends of the PCaPC beam 10 are integrally formed with the joint portion 2a so as to include the joint portion 2a of the column 2 at one end, and are both-end fixed beams. The length is set so that the joint 13 is located in a region where both the bending moment and the shearing force of the PCaPC beam 10 are relatively small. The axial direction of the PCaPC beam 10 refers to the direction of a straight line connecting the cross-sectional centers at both end surfaces of the beam 5.

  As shown in FIG. 4, the end piece 11 includes an upper flange portion 21 disposed at the upper end, a lower flange portion 22 disposed at the lower end, and the upper flange portion 21 and the lower flange portion 22. And a web portion 23 connected at the center in the width direction. The upper flange portion 21 and the lower flange portion 22 are formed to have the same thickness in the axial direction and the upper flange portion 21 is thicker than the lower flange portion 22. The web part 23 is formed so that its height gradually decreases from the joint part 2a side toward the central piece 12 side. Thereby, the end piece 11 has an arch shape in which the height gradually decreases from the joint portion 2a side toward the central piece 12 side.

  Further, as shown in FIG. 3, the lower flange portion 22 of the end piece 11 is formed wider than the upper flange portion 21 in the connecting portion 11b (cross section of FIG. 4) with the joint portion 2a. As shown in FIG. 5, the width of the joint end surface 11a with respect to the central piece 12 is the same as that of the web portion 23. Therefore, the end piece 11 has a T-shaped cross section at the joint end surface 11a, and has a substantially I-shaped cross section at other portions.

  As shown in FIG. 6, the central piece 12 is configured to have an upper flat plate portion 31 disposed at the upper end and a lower protruding portion 32 that protrudes downward from the center in the width direction of the upper flat plate portion 31. . The central piece 12 is formed to have the same shape (cross-section T-shape) and the same size as the joining end surface 11a (cross section in FIG. 5) of the end piece 11 over the entire length, and both joining end surfaces 12a to the end piece 11 are formed. The end piece 11 and the joining portion 13 that are disposed opposite to each other are directly joined to each other. That is, the upper flat plate portion 31 is joined to the upper flange portion 21 of the end piece 11, and the lower protruding portion 32 is joined to the lower flange portion 22 of the end piece 11.

  Here, the direct joining means joining without placing cast-in-place concrete on the joining portion 13 (between the joining end faces 11a and 12a) of the adjacent pieces 11 and 12 as shown in FIG. In this embodiment, a gap of about 20 mm is provided between the joint end faces 11a and 12a, and the gap 14 is filled with the grout 14 so that the end piece 11 and the central piece 12 are in close contact with each other, as will be described later. Both pieces 11 and 12 are joined to each other by joining the main bars 25 and 35. In addition, if the flatness of both joining end surfaces 11a and 12a can be ensured and both pieces 11 and 12 can be closely adhered, the joining end surfaces 11a and 12a are in direct contact with each other without filling the grout 14. May be joined together.

  Since each of the pieces 11 and 12 has such a shape, the beam formation of the PCaPC beam 10 is reduced in the central portion as shown in FIG. 2, and the lower end surface thereof and a ceiling panel (not shown) disposed below the lower end surface are provided. A space in which piping and the like can be arranged is formed between the two. On the PCaPC beam 10, a slab panel 15 (here, made of PCa having a plurality of core holes) is placed, and a top concrete 16 made of cast-in-place concrete is formed thereon. Thus, a synthetic floor in which the slab panel 15 and the top concrete 16 are integrated is constructed. Instead of using the slab panel 15, the slab may be constructed by on-site concrete.

  As shown in FIGS. 4 and 5, in the upper flange portion 21 of the end piece 11, a total of 12 upper reinforcing bars 25 a and 6 lower reinforcing bars 25 b as the main reinforcing bars 25 are parallel to the axial direction. In addition, barbs 26a that are arranged at equal intervals and surround these main bars 25 are arranged at predetermined intervals in the axial direction. In addition, a plurality of straight pretension tension members 27 (here, a total of twelve in two stages and six rows) are arranged in parallel to the axial direction inside the main bars 25 (25a, 25b) and the gluteal bars 26a. .

  In the lower flange portion 22 of the end piece 11, the six lower end bars 25 c and 25 d are arranged at equal intervals as main bars in the connecting portion 11 b (FIG. 4) with the joint portion 2 a, Two lower end bars 25c are arranged on the joining end face 11a (cross section in FIG. 5). These main bars 25 (25c, 25d) are arranged in a curved shape along the arch shape of the lower surface of the lower flange portion 22, while the lower ends located at both ends in the width direction in a plan view as shown in FIG. In accordance with the change in the width of the lower flange portion 22, the streak 25 c is disposed obliquely with respect to the axial direction and protrudes from the joint end surface 11 a, and the other lower end streaks 25 d are disposed parallel to the axial direction and are disposed on the joint end surface 11 a. It is said that the length is not reached. Returning to FIGS. 4 and 5, the barbs 26 b are arranged at predetermined intervals while changing the width dimension so as to surround the main bars 25 (25 c, 25 d). In addition, two upper end bars 25e are arranged at both the left and right ends inside the barb 26b.

  Inside the web portion 23 of the end piece 11 (more precisely, in the region where the web portion 23 is vertically extended), the upper and lower four main bars 25 arranged at the center in the width direction of the upper flange portion 21 and the lower side Reinforcing bars 26c surrounding the two main reinforcing bars 25 arranged at the center in the width direction of the flange portion 22 are arranged at predetermined intervals while changing the height dimension according to the change in the height of the web portion 23.

  As shown in FIG. 6, the four upper end bars 35 a are arranged as main bars 35 at equal intervals in the axial direction inside the upper flat plate portion 31 of the central piece 12, so as to surround these main bars 35. The streaks 36a are arranged at a predetermined interval. In addition, two lower end bars 35b are arranged at the left and right ends inside the barb 36a.

  Inside the lower protrusion 32 of the central piece 12, two lower end bars 35 c are arranged in parallel to the axial direction as main bars 35. The barbs 36c are arranged at a predetermined interval so as to surround the two upper end bars 35a arranged at the center of the upper flange portion 21 in the width direction and the two lower end bars 35c of the lower protrusion 32. In addition, a plurality of linear pretension tension members 37 (in this case, a total of six in three stages and two rows) are arranged in the lower part on the inner side of the barb 36c in parallel with the axial direction.

  Reinforcing bar joints 40 are attached to both ends of the six main bars 35 (35a, 35c) arranged in the center piece 12 in a manner of being embedded in the center piece 12 as shown in FIG. The reinforcing bar joint 40 joins the main bar 35 of the central piece 12 and the corresponding main bar 25 of the end piece 11 to each other. Specifically, as shown in the partially enlarged view of FIG. 7, the reinforcing bar joint 40 is attached to the end of the main bar 35 of the central piece 12 and is embedded so as to face the joining end surface 12 a of the central piece 12. And a grout 42 that is filled between the inner surface of the sleeve 41 and the outer surface of the main bar 25 in a state where the main bar 25 of the end piece 11 is inserted into the sleeve 41.

Therefore, only the six main bars 25 arranged at positions corresponding to the main bars 35 of the central piece 12 among the 14 main bars 25 arranged on the joining end surface 11 a of the end piece 11 are inserted into the sleeve 41. Therefore, it arrange | positions so that it may extend from the joining end surface 11a, and the remaining 8 main reinforcing bars 25 are arrange | positioned so that it may not extend from the joining end surface 11a.

  On the other hand, in the joint portion 2a formed integrally with the end piece 11, a plurality of sheaths 17 are arranged at positions corresponding to the columnar main bars 51 along the periphery in plan view (FIG. 3). The sheath 17 is embedded so as to extend from the upper surface to the lower surface of the joint portion 2a, and a vertical through hole is formed in the joint portion 2a. The sheath 17 is formed on the lower surface of the PCa column piece 50 disposed above the sheath portion 2a. The protruding column main reinforcement 51 (see FIG. 9F) is inserted so as to reach the PCa column piece 50 disposed below the column main reinforcement 51.

  Referring to FIG. 9F, a sleeve 53 of a reinforcing bar joint 52 attached to the upper end of the column main bar 51 is embedded in the PCa column piece 50 so as to face the upper surface of the PCa column piece 50. And the column main reinforcement 51 is arrange | positioned so that it may extend below from the lower surface of the PCa pillar piece 50, the extension part of the column main reinforcement 51 penetrates the sheath 17 of the edge piece 11, and the lower PCa pillar piece 50 The sheath 17 and the sleeve 53 are filled with the grout 54 while being inserted into the sleeve 53, whereby the PCa pillar piece 50, the end piece 11 and the upper PCa pillar piece 50 are integrally joined. Here again, grout may be filled between the joint end faces facing each other so that the pieces 11 and 50 are in close contact with each other.

  The end piece 11 and the center piece 12 are precast products that are molded in dedicated PC factories, respectively, and the concrete is cast in a tensioned state by applying tension to the pretension tension members 27 and 37 installed in the molds. It is a pre-tension type PCaPC molded product that is installed and removes the tension after the concrete is hardened to introduce prestress into the concrete. As the pretension tension members 27 and 37, a PC steel wire having a circular surface with a smooth surface may be used, but an indented PC steel wire having irregularities formed on the surface may be used, or a PC steel wire may be used at the end of the wire. It is desirable to secure adhesion strength by providing a crimping grip.

  Thus, in the pre-tension type PC beam, in order to fix the pre-tension tension members 27 and 37 by adhering to the concrete, the tension is higher than that of the post-tension type PC beam in which fixing is performed by fixing tools and grout injection. Although it is difficult to introduce prestress at the end of the material, as shown in FIG. 2, the end piece 11 is formed to include the joint portion 2a, and the pretension tension material 27 is formed on the side end surface of the joint portion 2a. As a result, the necessary prestress can be introduced also to the upper portion of the connecting portion 11b of the PCaPC beam 10 with the greatest bending moment and the large tensile force acting on the joint portion 2a. Yes.

  On the other hand, since the pretension tension material 27 of the end piece 11 is arranged at the upper part and the pretension tension material 37 of the center piece 12 is arranged at the lower part, the tension materials 27 and 37 are not joined to each other. Even in the vicinity of the joint 13 of the end piece 11 and in the vicinity of the joint 13 of the central piece 12, the end of the tendon material is used for fixing, so that no prestress is introduced. However, as described above, since the joint portion 13 is provided in a region where the bending moment is small, the cross-sectional performance of this portion does not become a problem, and the axial direction of the central piece 12 where the tensile force increases due to the bending moment. Necessary prestress is introduced in the lower center.

  Since the end piece 11 and the central piece 12 are directly joined by joining the main bars 25 and 35, it is not necessary to place the cast-in-place concrete on the joint 13 and a mold for that purpose. Work such as frame assembly, rebar assembly, concrete placement, and curing is unnecessary, and the assembly and installation work of the PCaPC beam 10 becomes easy and the work period can be shortened.

  Further, the number of the main bars 25 of the end piece 11 is larger than the number of the main bars 35 of the center piece 12, and the reinforcing bar joints 40 are installed according to the number of the main bars 35 of the center piece 12. For the part piece 11 and the central piece 12, it is possible to arrange the optimal main bars 25 and 35 respectively, and in the joint part 13, by joining the main bars 25 and 35 to the central piece 12 on the side where the number is small, The required bending strength and shear strength are ensured, and the construction is facilitated. Moreover, since it becomes easy to secure the installation space of the rebar joint 40 by this, the small cross section around the junction part 13 is attained, and the PCaPC beam 10 of the said shape is realizable.

  Further, the reinforcing bar joint 40 is inserted into the sleeve 41 with the sleeve 41 attached to the end of the main bar 35 of the central piece 12 and the main bar 25 of the end piece 11 formed so as to extend from the joining end surface 11a. In this way, each piece 11, 12 is moved in the axial direction, and the extending main bar 25 is inserted into the sleeve 41 so as to be the main bar. 25 and 35 can be easily and reliably joined.

  Then, the end piece 11 is formed so that its height gradually decreases from the mouthpiece 2 a side toward the central piece 12 side, and the central piece 12 has the same height as the joining end surface 11 a of the end piece 11. This makes it possible to secure installation space for ducts and piping for air conditioning, water supply / drainage, power supply, etc., without reducing the ceiling height, especially for commercial buildings such as office buildings. It will provide added value.

  Further, the end piece 11 has an upper flange portion 21, a lower flange portion 22 and a web portion 23 so that the web portion 23 gradually decreases in height from the joint portion 2a side toward the central piece 12 side. The lower flange portion 22 is formed wider than the upper flange portion 21 in the connecting portion 11b with the joint portion 2a, and the width is gradually reduced from the joint portion 2a toward the central piece 12 side. In this way, it is possible to secure an installation space for piping under the PCaPC beam 10 and to effectively use the secondary moment of section at the connection portion 11b with the joint portion 2a where the bending stress of the beam 5 is the largest. The beam can be made lighter or the design load can be increased.

  In addition, when the main bar 25 of the end piece 11 and the main bar 35 of the central piece 12 are joined by the reinforcing bar joint 40, it is necessary to move in the axial direction. The lower column piece 50 on which the sheath 17 is inserted so that the column main reinforcing bars 51 projectingly formed on the lower surface of the PCa column piece 50 on the upper floor reach the PCa column piece 50 on the current floor, and the PCaPC beam 10 is placed thereon. Since the column main reinforcement 51 does not extend from the beam, the beam piece can be assembled directly on the PCa column piece 50. Therefore, a large lifting machine is not required for installing the PCaPC beam 10, and only an existing tower crane is assembled.・ Setting work can be performed. Therefore, a dedicated yard is not required for assembling the PCaPC beam 10.

  In addition, since the connection structure to the pillar 2 of the PCa beam member which comprises the beam 3 extended in a column direction is not directly related to this invention, illustration and detailed description are abbreviate | omitted, However, For example, end piece 11 embeds a rebar joint sleeve in the joint 2a, or arranges the beam main bar to extend from the joint end face to the PCa beam member, and embeds the rebar joint sleeve in the joint end face of the PCa beam member. Alternatively, the end piece 11 may be configured so as to integrally include the end portion of the beam 3 divided in addition to the joint portion 2a of the column 2, and the joint end surface of the beam end portion is PCa. You may make it join a beam member.

  Next, the assembly / installation procedure of the PCaPC beam 10 will be described with reference to FIGS. 8 and 9.

  First, as shown to (A), the end piece 11 and the center piece 12 which have the structure mentioned above, and the PCa pillar piece 50 are manufactured in a PC factory etc., and this is carried in to the spot with a trailer etc. Next, as shown in (B), the two bases 60 prepared in advance to support the vicinity of the joint portion 13 of the PCaPC beam 10 are arranged between the pair of PCa column pieces 50 (columns 2). . The pedestal 60 supports the end piece 11 and the central piece 12 during assembly, and has a height adjusting means 61 such as a screw jack incorporated so that the height can be adjusted and removed after assembly. Is. Here, each gantry 60 is configured to include a plurality of pipe supports for formwork support. Then, as shown to (C), one end piece 11 is lifted with the tower crane which is not shown in figure, and the one end is arrange | positioned in the predetermined position on the PCa pillar piece 50 in the state supported by the mount frame 60. FIG. In this state, the six main bars 25 extending from the joint end surface 11a of the end piece 11 extend in the horizontal direction.

  Next, as shown in (D), the central piece 12 is similarly lifted horizontally by a tower crane and moved horizontally on the gantry 60, and the main bar 25 of the end piece 11 is inserted into the sleeve 41 of the central piece 12. However, it is moved to a predetermined position (a position where a gap for filling the grout 14 is formed between the joining end faces 11a and 12a). Then, both ends thereof are supported by the two bases 60. Similarly, as shown in (E), the remaining end piece 11 is lifted horizontally by a tower crane and moved horizontally on the gantry 60 and the PCa pillar piece 50, and the main bar 25 of the end piece 11 is moved to the central piece 12. The sleeve 41 is moved to a predetermined position while being inserted into the sleeve 41, and both ends thereof are supported by the gantry 60 and the PCa pillar piece 50.

  Thereafter, a grout 42 such as a non-shrink mortar is injected into the sleeve 41 embedded in the central piece 12 to fix the main muscle 25 and the sleeve 41, and in the gap of the joint portion 13 between the end piece 11 and the central piece 12. Similarly, the grout 14 is filled and the adjacent pieces 11 and 12 are directly joined.

  Thereafter, or in parallel with this, as shown in (F), the upper-floor PCa pillar piece 50 is fixed on the joint portion 2a, and the upper-floor PCa pillar piece 50, the end piece 11 and the current floor The PCa pillar pieces 50 are integrally joined. Specifically, the PCa column piece 50 is lifted in a vertical state, lowered with the column main reinforcement 51 protruding vertically from the lower surface, and the extending column main reinforcement 51 is inserted into the sheath 17 of the joint portion 2a. When the PCa column piece 50 is placed on the upper surface of the joint portion 2 a, the lower end portion of the column main bar 51 is inserted into the sleeve 53 of the lower PCa column piece 50, so that the grout 54 is attached to the sheath 17 and the sleeve 53. By injecting and connecting the column main bars 51 of the upper and lower PCa column pieces 50, the PCa column piece 50 on the upper floor, the end piece 11 and the PCa column piece 50 on the current floor are integrally joined. As a result, the assembly and installation work of the PCaPC beams 10 for the first floor is completed, and thus the frame structure 1 of the multi-layer building is constructed by repeating the above procedure.

  This is the end of the description of specific embodiments, but the present invention is not limited to these embodiments. The specific shape, arrangement, quantity, and the like of each member can be changed as appropriate without departing from the spirit of the present invention. For example, in the above embodiment, the PCaPC beam 10 is assembled while the pieces 11 and 12 are arranged at predetermined installation positions. However, if there is equipment capable of lifting the assembled PCaPC beam 10, what is the original installation position? After the assembly work is performed in another assembly yard, the PCaPC beam 10 may be arranged at a predetermined installation position. In this way, the PCaPC beam 10 is also applied to a method of placing the PCaPC beam 10 with the column main reinforcement 51 extending from the upper surface of the PCa column piece 50 on which the PCaPC beam 10 is to be placed. Can do. Moreover, in the said embodiment, although the center piece 12 is comprised so that it may have a fixed cross-sectional shape, you may make it a cross-sectional shape deform | transform. On the other hand, the end piece 11 is configured such that the height gradually decreases over the entire length of the beam portion, but may be configured to have the same cross section in some sections. Furthermore, in the said embodiment, although all the main reinforcements 25 arrange | positioned at the upper side flange part 21 of the end piece 11 are set to the length which reaches the joining end surface 11a, about the main reinforcement 25 which is not joined to the rebar joint 40, The length may be shortened so as not to reach the joining end surface 11a. In addition, the constituent elements of the PCaPC beam 10 and the assembly / installation steps of the PCaPC beam 10 according to the present invention described in the above embodiment are not necessarily all necessary, and are appropriately disposed as long as they do not depart from the gist of the present invention. It is possible to select.

DESCRIPTION OF SYMBOLS 1 Frame structure 2 Column 2a Joint part 10 PCaPC beam 11 End piece 11a Joining end surface 11b Connection part 12 Central piece 12a Joining end face 13 Joining part 17 Sheath 21 Upper flange part 22 Lower flange part 23 Web part 25 Main reinforcement (end part) Piece 11)
27 Pretension tendon (end piece 11)
35 Main muscle (center piece 12)
37 Pretension tendon (central piece 12)
40 Reinforcing Bar Joint 41 Sleeve 42 Grout 50 PCa Column Piece 51 Column Main Bar

Claims (4)

A precast prestressed concrete beam composed of three pieces divided in the axial direction and spanned between a pair of columns,
Each of the two end pieces arranged at the end in the axial direction includes a joint part of the column integrally formed at one end, a main bar extending in the axial direction, and a pretension tension material arranged at the upper part. Have
The central piece arranged in the axial center has a main bar extending in the axial direction and a pretensioning tension material arranged in the lower part,
By joining the main bar of the end piece and the main bar of the center piece by a reinforcing bar connecting means, the end piece and the center piece are directly bonded to each other ,
The number of main bars of the end piece is greater than the number of main bars of the central piece,
The precast prestressed concrete beam, wherein the reinforcing bar joining means is installed according to the number of main bars of the central piece . A precast prestressed concrete beam composed of three pieces divided in the axial direction and spanned between a pair of columns,
Each of the two end pieces arranged at the end in the axial direction includes a joint part of the column integrally formed at one end, a main bar extending in the axial direction, and a pretension tension material arranged at the upper part. Have
The central piece arranged in the axial center has a main bar extending in the axial direction and a pretensioning tension material arranged in the lower part,
By joining the main bar of the end piece and the main bar of the center piece by a reinforcing bar connecting means, the end piece and the center piece are directly bonded to each other ,
The end piece is formed such that its height gradually decreases from the joint portion side toward the central piece side,
The precast prestressed concrete beam , wherein the central piece is formed to have the same height as the joint end surface of the end piece . A precast prestressed concrete beam composed of three pieces divided in the axial direction and spanned between a pair of columns,
Each of the two end pieces arranged at the end in the axial direction includes a joint part of the column integrally formed at one end, a main bar extending in the axial direction, and a pretension tension material arranged at the upper part. Have
The central piece arranged in the axial center has a main bar extending in the axial direction and a pretensioning tension material arranged in the lower part,
By joining the main bar of the end piece and the main bar of the center piece by a reinforcing bar connecting means, the end piece and the center piece are directly bonded to each other ,
The end piece has an upper flange portion, a lower flange portion, and a web portion connecting the upper flange portion and the lower flange portion,
The web part is formed such that its height gradually decreases from the joint part side toward the central piece side,
The lower flange portion is formed wider than the upper flange portion at the connection portion with the joint portion, and is formed so that the width gradually decreases from the joint portion side toward the central piece side. precast prestressed concrete beams, characterized in that it is. The reinforcing bar joining means includes a sleeve member, and a grout filled in the sleeve member in a state where the main reinforcement is inserted into the sleeve member,
In one of the central piece and the end piece, the main bar is arranged so as to extend from the joint end face,
The precast prestressed concrete according to any one of claims 1 to 3 , wherein the sleeve member is embedded in the other of the center piece and the end piece so as to face the joining end surface. Beams.

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