JP2011006859A - Reinforced concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PC structure allowing erection of a precast beam of large cross section or large span without causing an increase in working man-hours and maintaining predetermined quality.SOLUTION: This reinforced concrete structure 1 includes a pair of columns 2 and a precast girder 3 with both ends joined to the pair of columns 2. The girder 3 is composed of two precast beam members 4 divided in the width direction.

Description

  The present invention relates to a reinforced concrete structure and relates to a technique for increasing the construction speed using a precast concrete beam.

  Conventionally, in reinforced concrete structures, a rigid frame structure in which a column and a beam are rigidly connected is widely used. The ramen structure is a framework in which pillars and beams are assembled in a lattice pattern, and a general structure is constructed of cast-in-place concrete. Since both the columns and the beams have a rectangular cross section, and one beam is joined to one surface of a column having four side surfaces, one for each of the four surfaces for the middle column, a total of four beams In total, three beams, one each on three sides, are joined to the outer peripheral column, and two beams, one each on two sides, are joined to the corner column.

  In recent years, reinforced concrete columns and beams have been factory-produced in advance with precast concrete (hereinafter referred to as PCa), and all precast concrete has been eliminated by placing and joining these PCa columns and PCa beams at the construction site. Construction methods are also being developed. According to this all-precast concrete method, the construction speed can be increased and the construction period can be greatly shortened, and by dividing the PCa beam in the longitudinal direction, it is possible to cope with a beam having a certain length of span.

  In addition, in a structure in which a seismic wall is constructed between column beams, a method of using a PCa beam and constructing the seismic wall with cast-in-place concrete is also known. In this construction method, it is necessary to cast the concrete after laying the upper beam and integrate the earthquake-resistant wall with the four column beams, but the earthquake-resistant wall formwork for concrete casting extends to the upper beam, It becomes difficult to fill the formwork with concrete. Therefore, the upper PCa beam is divided vertically, that is, divided into two in the width direction by the longitudinal and vertical dividing planes of the beam, and the divided PCa beam is installed at a predetermined interval, and then both divided beams are reinforced with reinforcing bars and threading. An invention that improves the filling and workability of concrete in the form wall for earthquake resistant walls by connecting with bolts and placing concrete from the gap between PCa beams to integrate the wall and both split beams. It has been proposed (Patent Document 1).

JP 2004-232328 A

  However, in the conventional all-precast concrete method, if the PCa beam is divided in the longitudinal direction, the allowable stress as the beam is reduced. Therefore, if the cross-sectional dimension or span of the beam increases, the PCa beam becomes larger and transported. And erection becomes difficult. Particularly, when the weight of the PCa beam increases, the lifting equipment for erection increases in size, so that the construction speed can be improved, but there is a problem that the construction cost is increased. As a means to solve this problem, there is a so-called semi-precast method in which only the lower part of the beam is made into PCa and the upper part of the beam is cast in place, but in this method, concrete placement work is more difficult than the all-precast concrete method. Increases construction speed.

  On the other hand, in the invention of Patent Document 1, since the PCa beam is vertically divided, the weight of the PCa beam per member is reduced, and it is not necessary to use a large lifting equipment for erection. Similarly, since cast-in-place concrete is used to integrate the split beams, there is a limit to improving the construction speed. In addition to the concrete placing work, in order to integrate both split beams, it is necessary to arrange the bars between the split beams and connect them with bolts through the split beams, further increasing the work man-hours. Invite. Furthermore, according to the present invention, it is difficult not only to economically increase the time and cost for construction but also to place concrete concretely so that no gaps are formed in every corner between split beams. In addition, there is a problem that it is difficult to ensure the quality or the quality varies.

  The present invention has been made in view of such a background. A reinforced concrete structure capable of laying a PCa beam having a large cross section or a large span and maintaining a certain quality without incurring an increase in work man-hours. The purpose is to provide.

  In order to solve the above problems, a first invention is a reinforced concrete structure (1) having a pair of columns (2, 12) and a precast concrete beam (3, 13) having both ends joined to the pair of columns. 11), the precast concrete beam (3, 13) is composed of a plurality of precast concrete beam pieces (4, 14) divided in the width direction.

  According to the present invention, by dividing the PCa beam in the width direction, it is possible to reduce the weight at the time of installation without reducing the cross-sectional performance of the entire beam. Therefore, even if the cross-sectional dimension and span of the beam are increased, transportation and installation can be easily performed. And since the divided PCa beam pieces do not need to be connected with on-site concrete after construction, they can achieve the same construction speed as the all-precast concrete method, compared with the half-precast method and the conventional on-site method. To improve the construction speed.

  Further, the second invention is the reinforced concrete structure (1, 11) according to the first invention, wherein the plurality of precast concrete beam pieces (4, 14) are provided after the concrete at the portion to be joined to the slab (5) is installed. It is characterized by being placed.

  According to the present invention, the joint portion with the slab can be placed simultaneously with the slab concrete, whereby the joint strength between the beam and the slab can be increased. Further, since the PCa beam piece is lighter by the amount of unplaced concrete, it can be easily transported and erected.

  The third invention is a reinforced concrete structure (11) according to the first or second invention, wherein the precast concrete beam (13) is not joined to the slab (5) and is at least one precast concrete beam for seismic load. It has a piece (15) and at least one precast concrete beam piece (14) for long-term loads joined to the slab (5).

  When installing a beam for seismic load and a beam for long-term load as a beam that connects a pair of columns, the beam for seismic load must be installed between the beams for long-term load that support the slab on each floor. Therefore, the size of the opening is limited. According to the present invention, since the beam for seismic load can be provided at the same height as the beam for long-term load, the size of the opening is not limited. In this way, because the seismic load beam and the long-term load beam can be provided without restricting the opening, even if the seismic load beam is damaged during an earthquake, the long-term load beam that supports the slab Damage can be suppressed and safety as a building can be improved.

  The fourth invention is the reinforced concrete structure (11) according to the third invention, wherein the precast concrete beam piece (14) for long-term load is joined to the column (12) only at the upper ends thereof. It is characterized by.

  According to this invention, the beam for a long-term load is joined to the column only at the upper part thereof, so that it is joined to the column in a state close to the pin support rather than as a fixed beam. As a result, safety can be further improved.

  According to a fifth aspect of the present invention, in the reinforced concrete structure (1, 11) according to the first or second aspect, at least one of the plurality of precast concrete beam pieces (4) is 4m. , 4r), having different cross-sectional performance.

  According to the present invention, PCa beam pieces having different cross-sectional performance can be prepared, and the cross-sectional performance of the beam can be varied by arbitrarily combining them, and the cross-sectional performance of the beam is optimized according to the part of the structure to be installed. Can be.

  According to a sixth invention, in the reinforced concrete structures (1, 11) according to the first to fifth inventions, post tension is applied to at least one of the plurality of precast concrete beam pieces (4, 14, 15). Is added.

  Since different stresses are generated in the beam during installation and loading, when pre-tension is introduced, only the tensile force considering these stresses can be applied to the beam. By introducing it, a tensile force exceeding the cross-sectional performance of the beam can be introduced into the beam in the pretension. In particular, when the concrete at the site to be joined to the slab is placed after erection, applying a tensile force after placing the slab concrete increases the cross-sectional performance of the beam, so that a greater tensile force can be applied.

  The seventh invention provides a reinforced concrete structure (21, 31) having a pair of columns (22, 32) and a beam (23, 33) joined at both ends to the pair of columns. , 33) is divided into three in the longitudinal direction, and has a central beam portion (23M, 33M) located at the center and two end beam portions (25b, 36) located at both ends. (23M, 33M) is composed of a plurality of precast concrete beam pieces (24, 34) divided in the width direction.

  According to the present invention, the weight of each PCa beam piece can be reduced by dividing the beam into three in the longitudinal direction and further dividing the central beam portion in the width direction to form PCa. In addition, even if the cross-sectional performance of the divided portion is lowered by setting the dividing position in the longitudinal direction in the vicinity of the position where the bending moment is minimized, it is possible to avoid the allowable stress as a whole beam from being lowered. Thereby, the cross-sectional dimension and span of a beam can be enlarged. It is the same as the first invention that it is easy to carry and erection and has a high construction speed.

  The eighth invention is the reinforced concrete structure (21) according to the seventh invention, wherein at least one of the end beam portions (25b) is made of precast concrete (25) integrally formed with the pillar (25a). It is characterized by becoming.

  According to the present invention, the column is made of PCa and the end beam portion is integrated with the column, so that the strength of the column beam joint can be ensured, the number of joints and assembly man-hours can be reduced, and the construction cost is reduced. In addition, the construction speed can be improved. In particular, in the case of an intermediate beam, joint portions and assembly man-hours can be greatly reduced by integrally forming the end beam portions of the beam that intersect in a cross shape. In addition, it is also possible to divide | separate this column beam junction part into the column for one layer separately.

  The ninth invention is a reinforced concrete structure (31) according to the seventh invention, wherein at least one of the end beam portions (36) is made of precast concrete formed separately from the columns (32, 35). It is characterized by becoming.

  According to the present invention, by setting the end beam portion to PCa, it is possible to reduce the cast-in-place concrete and increase the construction speed. In addition, compared with the eighth invention, it is impossible to reduce the number of joints and the number of assembling steps, but it is possible to reduce the weight of the lifting member, so that it is not necessary to use a large lifting equipment when installing.

  According to the present invention, it is possible to provide a PC structure capable of laying a PCa beam having a large cross section or a large span without increasing the work man-hours and maintaining a certain quality.

The top view of the reinforced concrete structure concerning a 1st embodiment II-II sectional view in FIG. III-III sectional view in FIG. Cross-sectional view of a girder according to a first modified embodiment Cross-sectional view of a girder according to a second modified embodiment Cross-sectional view of a girder according to a second embodiment VII-VII sectional view in FIG. VIII-VIII sectional view in FIG. The top view of the structure concerning a 3rd embodiment XX sectional view in FIG. XI-XI sectional view in FIG. Vertical sectional view of a beam according to the fourth embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
First, the reinforced concrete structure 1 which concerns on 1st Embodiment with reference to FIGS. 1-3 is demonstrated. As shown in FIG. 1, the reinforced concrete structure 1 is a frame of a rigid frame structure that constitutes a multi-layered building. The reinforced concrete structure 1 improves the earthquake resistance of a plurality of pillars 2 arranged at predetermined intervals along two axes orthogonal to each other on a horizontal plane (hereinafter referred to as X axis and Y axis), and In order to support a slab 5 and a small beam, which will be described later, each of the layers is composed of a plurality of large beams 3 arranged along the X axis and the Y axis so as to connect the columns 2 to each other. The pillar 2 is constructed by connecting PCa pillar members 2a having a rectangular cross section, which are manufactured in advance in a factory so as to have a length (height) corresponding to a single floor height. The large beam 3 is composed of a PCa beam member 4 (beam piece) having a substantially rectangular cross section manufactured in advance in a factory so as to have a length corresponding to the horizontal distance between the pair of columns 2.

  As shown in FIG. 2, the large beam 3 is composed of two PCa beam members 4 arranged in parallel with a predetermined distance d, and has a structure divided into two in the width direction. In other words, the large beam 3 is vertically divided into two PCa beam members 4 by a dividing surface extending in the longitudinal direction and in the vertical direction, and the two PCa beam members 4 are parallel to each other so as to form a constant interval d. Is arranged. Each PCa beam member 4 has the same cross-sectional shape, and the same cross-sectional performance, that is, the type, size and arrangement of reinforcing bars and the type of concrete are the same. Therefore, both PCa beam members 4 have the same allowable stress, and both ends in the longitudinal direction are joined to the facing surfaces of the pair of columns 2 having a rectangular cross section. The predetermined distance d may be set to such an extent that adjacent PCa beam members 4 do not interfere with each other due to manufacturing errors of the PCa beam members 4 and installation errors of the PCa beam members 4 and the columns 2.

  Although detailed illustration is omitted, the PCa column member 2a and the PCa beam member 4 have upper end bars 4a and lower end bars 4b protruding from the joint end faces, or joints for joining the upper end bars 4a and the lower end bars 4b. The means are inserted so as to be exposed at the joining end face, and after being placed in place by a tower crane (not shown), the ends of the upper and lower end bars 4a and 4b are joined by the joint means, and further, in the gap of the joining part. Cement milk and non-shrink mortar are filled and rigidly joined together. In addition, as a joint means, mechanical joints, such as a metal sleeve of a mortar filling type, a screw type, a filling type, or a steel pipe crimping type, etc. can be used, for example. Or you may connect the edge parts of the rebar 4a which opposes by welding, gas pressure welding, and a lap joint. Further, regarding the method of assembling and joining these PCa members, Japanese Patent Laid-Open Nos. 2000-144894, 2004-278257, 2004-346687, and 2008- Since it is described in detail in Japanese Patent No. 31839, it is omitted here.

  In the present embodiment, each PCa beam member 4 has a structure in which a slab 5 is joined to the upper part of the side surface and the upper surface thereof is flush with the upper surface of the slab 5. As for each PCa beam member 4, the concrete of the site | part which overlaps with the slab 5 in the height direction is not laid at the time of construction, and the arranged upper end reinforcement 4a has been exposed from the concrete. In order to avoid complication of the drawing, the shear reinforcement bars of the PCa beam member 4 are omitted in FIG. 2, and the upper end bars 4a, the lower end bars 4b and the shear reinforcement bars of the PCa beam member 4 are omitted in FIG. As shown.

  When constructing the reinforced concrete structure 1 using each of the PCa beam members 4 made of PCa, first, the PCa beam members 4 are lifted one by one by a tower crane, and a pair of columns 2 as shown in FIG. After erection, the PCa beam members 4 are joined to the pillars 2 over the entire surface except the part where the concrete is not yet placed, and the concrete is placed simultaneously with the slab concrete, so that Is joined to the pillar 2.

  In this way, the large beam 3 is composed of a plurality of PCa beam members 4 that are divided into two in the width direction. Weight can be halved. Therefore, even if the cross-sectional dimension of the large beam 3, that is, the total sectional dimension of the PCa beam member 4 or the span of the large beam 3 is increased, the weight of each PCa beam member 4 can be reduced, so that transportation and erection can be easily performed. it can. As a result, the main construction method for assembling a beam made of PCa can be employed.

  Moreover, since the concrete of the site | part which overlaps with the slab of each PCa beam member 4 is not cast at the time of construction, the weight of each PCa beam member 4 becomes smaller, and conveyance and construction are easier. Further, since the PCa beam member 4 can be placed at the same time as the slab concrete at the joint portion with the slab 5, it can be joined to the slab with high joint strength.

  In the present embodiment, each PCa beam member 4 has an upper portion in which concrete is not placed at the time of factory production, but may be in a form in which concrete is placed up to the upper end at the time of factory production. In this case, the PCa beam member 4 may be in a form in which the PCa beam member 4 is joined to the slab 5 at the upper part of the side surface, a form in which the PCa beam member 4 is joined to the slab 5 on the upper surface thereof, or a combination of these. And, since the divided PCa beam members 4 do not need to be connected by on-site concrete after installation, the construction speed equivalent to the all-precast concrete method can be realized. Compared to the construction speed can be increased. In addition, since the cast-in-place concrete is not used for the construction of the girder 3, stable quality can be ensured.

<First Modified Embodiment>
Next, a first modified embodiment of the first embodiment will be described with reference to FIG. 4 is a cross-sectional view taken along the line II-II in FIG. 1, that is, a cross-section of the large beam 3 corresponding to FIG. As shown in FIG. 4, in this modified embodiment, the two PCa beam members 4 formed by dividing the large beam 3 in the width direction have the same cross-sectional shape as the first embodiment, and have the same cross-sectional performance. However, the interval d is set larger than that in the first embodiment. The installation method of the large beam 3 is the same as that of 1st Embodiment, and each PCa beam member 4 is each constructed by a pair of pillar 2 with the tower crane which is not shown in figure.

  In the first embodiment, the distance d is set to such an extent that the adjacent PCa beam members 4 do not interfere with each other. However, by setting the distance d large in this way, for example, lighting equipment or By arranging the wiring or fire fighting equipment such as a smoke detector or a sprinkler between the PCa beam members 4, these equipment can be installed without protruding from the housing.

<Second Modified Embodiment>
Next, a second modified embodiment of the first embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view of the girder 3 corresponding to FIG. As shown in the figure, in this modified embodiment, the large beam 3 is divided into three in the width direction, and three PCa beam members 4 having the same cross-sectional shape extending in parallel with each other are installed on the pair of columns 2. In the case of this modified embodiment as well, all the three PCa beam members 4 are joined to the opposing surfaces of the pair of columns 2 having a rectangular cross section.

  The three PCa beam members 4 arranged in parallel have different cross-sectional performance. Specifically, the PCa beam members 4l and 4r arranged at both ends in the horizontal direction (left and right ends in the figure) have four upper and lower bars 4a and 4b arranged in two upper and lower stages, respectively. On the other hand, the PCa beam member 4m arranged at the center in the horizontal direction has three upper end bars 4a and three lower end bars 4b arranged in two upper and lower stages. Further, the concrete of the PCa beam member 4m arranged at the center in the horizontal direction has a lower compressive strength than the concrete of the PCa beam members 4l and 4r arranged at both ends in the horizontal direction.

  Thus, by dividing the large beam 3 into three or more PCa beam members 4, the weight of one PCa beam member 4 can be further reduced, so that the reinforced concrete structure 1 in which the large beam 3 has a larger cross section or The main construction method for assembling a beam made of PCa can be adopted for the reinforced concrete structure 1 in which the span of the large beam 3 is further increased.

  Moreover, in the building of a multilayer structure, the cross-sectional performance requested | required of the big beam 3 changes with a hierarchy and a position. On the other hand, when manufacturing the member of the reinforced concrete structure 1 with PCa, it is desirable to reduce the standard as much as possible in consideration of productivity. For this reason, PCa members are often manufactured to a standard that is consistent with the largest required performance. In such cases, high-performance and expensive members are used even in parts that do not require large cross-sectional performance. Incurs an increase in construction cost. Therefore, as described above, by preparing a plurality of types of PCa beam members 4 having the same shape with different cross-sectional performances, and combining them according to the cross-sectional performances of the large beams 3 required according to the level and position to be installed. Thus, it is possible to easily construct the optimal beam 3 that satisfies the required performance and does not become excessive performance, and can reduce the construction cost.

<< Second Embodiment >>
Next, the reinforced concrete structure 11 according to the second embodiment will be described with reference to FIGS. In addition, the description which overlaps with 1st Embodiment is abbreviate | omitted. The same applies to the following embodiments. The reinforced concrete structure 11 according to the present embodiment has the same shape and arrangement as the first embodiment, that is, FIG. 6 is a transverse sectional view of the large beam 13 corresponding to FIG. 2, FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6, showing a longitudinal section of the beam member 14 for long-term load, and FIG. It is VIII-VIII sectional drawing of this, Comprising: The longitudinal cross-section of the beam member 15 for an earthquake load is shown.

  As shown in FIG. 6, the large beam 13 is composed of a PCa beam member divided into two in the width direction. Both PCa beam members have rectangular cross sections with the same width, the lower surfaces are positioned at the same height, and are arranged in parallel with a predetermined distance d. On the other hand, in the beam formation, one (left side in the figure) is larger than the other (right side in the figure). The slab 5 is constructed at a height position above the upper surface of the other PCa beam member and overlapping the upper portion of the one PCa beam member. That is, one PCa beam member is for long-term load in which the slab 5 is joined to the upper portion thereof to support the load of the slab 5 for a long time (hereinafter referred to as a long-term load beam member 14), and the other PCa beam member is The seismic load is not applied to the slab 5 and does not support the load of the slab 5 (hereinafter referred to as a seismic load beam member 15). The long-term load beam member 14 and the seismic load beam member 15 have different cross-sectional shapes and have different cross-sectional performances.

  As shown in FIG. 7, the long-term load beam member 14 is joined to the pair of columns 12 with both ends in the longitudinal direction having only upper portions thereof. More specifically, the beam member 14 for a long-term load has a concrete portion at the lower part of both ends as a notch 14c, and the upper end bar 14a is bonded to the column 12, but the lower end bar 14b is not bonded to the column 12, The end portion is bent upward to form a hook for fixing to the concrete of the long-term load beam member 14. Further, a sheath 16 extending in the longitudinal direction is embedded in the lower portion of the beam member 14 for long-term load, and a tension material such as a PC steel wire is inserted into the sheath 16 so that the tensioned PC steel wire is grouted. By fixing, the post-tension is applied to the long-term load beam member 14. In this embodiment, the column 12 for one layer is composed of two PCa column members 12a, which are a joint portion to which the beam members 14 and 15 are joined and a column portion disposed above the joint portion. Thus, the weight reduction of the PCa column member 12a is achieved.

  In this way, the post-tension is applied to the beam member 14 for a long-term load, and the allowable bending stress is sufficiently ensured by being joined to the column 12 in a manner close to the pin support structure with the upper portions at both ends. Stress is less likely to occur at the beam-column joint. Therefore, the long-term load beam member 14 is not greatly damaged even during an earthquake. Therefore, even if an earthquake occurs, the slab 5 supported by the beam member 14 for long-term load does not fall and the blame passage of the person on the upper floor is not blocked, and the safety of the building is improved. ing.

  On the other hand, as shown in FIG. 8, the beam member for seismic load 15 is rigidly joined to the pair of columns 12 with the entire cross section at both ends in the longitudinal direction. More specifically, the seismic load beam member 15 is joined to the column 12 in a state in which both the upper end bars 15a and the lower end bars 15b extend in the horizontal direction. That is, the seismic load beam member 15 fulfills the function of taking stress during an earthquake, making it difficult for the long-term load beam member 14 to generate stress. As a result, the seismic load beam member 15 is easily damaged during an earthquake, but the seismic load beam member 15 does not support the slab 5, so that the safety of the building is maintained.

<< Third Embodiment >>
Next, the reinforced concrete structure 21 according to the third embodiment will be described with reference to FIGS. Similar to the first embodiment, the reinforced concrete structure 21 is a housing of a multi-layered structure, and has a plurality of pillars 22 and a plurality of large beams 23 that connect adjacent pillars 22 to each other in the first embodiment. It is the same. Moreover, the pillar 22 and the large beam 23 are each constructed by a member made of PCa.

  As shown in FIGS. 9 to 11, the reinforced concrete structure 21 includes a PCa column member 22 a, a PCa joint member 25, and a PCa beam member 24 as PCa members constituting the columns 22 and the large beams 23. ing. The PCa joint member 25 is for joining the PCa column member 22a and the PCa beam member 24, and configures a column portion 25a that constitutes a part of the column 22 in the longitudinal direction and a part of the longitudinal direction of the large beam 23. The beam portion 25b is integrally formed. The PCa beam member 24 is a beam piece obtained by dividing the large beam 23 into three parts in the longitudinal direction and further dividing the central beam part 23M located at the center into two parts in the width direction. Configure. The column 22 having a length corresponding to one layer is composed of one PCa column member 22a and one PCa joint member 25, and one span of the large beam 23 is opposite to the pair of PCa joint members 25. Each beam portion 25b and a pair of PCa beam members 24 connecting them.

  As shown in FIG. 10, the upper end stripe 24a and the lower end stripe 24b of the PCa beam member 24 are joined to the joint end surfaces of the beam portion 25b of the PCa joint member 25 with the PCa beam member 24 at the corresponding positions. The joint means 25c is inserted. Each of the PCa beam members 24 is connected to the joint means 25c with the upper end stripes 24a and the lower end stripes 24b at both ends thereof, and a large beam together with the PCa joint member 25 in which each joint portion is filled with cement milk or the like. 23. Note that the length L of the beam portion 25b of the PCa joint member 25 is preferably set to be near the position where the bending moment of the large beam 23 is minimized. By setting the length of the beam portion 25b in this way, it is possible to avoid a decrease in the allowable stress of the large beam 23.

  As described above, each PCa beam member 24 is made shorter than the length of the large beam 23, that is, the span between the beams of the reinforced concrete structure 21 and the span of the beam line, thereby reducing the weight of the member lifted by the tower crane. 10 and 11, the PCa beam member 24 may be formed with a plurality of through holes 24c extending in the beam width direction at intermediate positions in the height direction. By forming the through hole 24c in this manner, the PCa beam member 24 can be reduced in weight without causing a reduction in allowable stress in the large beam 23.

<< Fourth Embodiment >>
Furthermore, with reference to FIG. 12, the reinforced concrete structure 31 which concerns on 4th Embodiment is demonstrated. In the reinforced concrete structure 31 of the present embodiment, the PCa joint member 25 in the third embodiment includes a PCa joint member 35 that constitutes only a part of the column 32, and a PCa end beam that constitutes only the end portion of the large beam 33. The third embodiment is different from the third embodiment in that the member 36 is a separate member.

  The upper end bar 36a and the lower end bar 36b of the PCa end beam member 36 are joined to joint means 35c inserted into the PCa joint member 35, and the upper end bar 34a and the lower end bar 34b of the PCa beam member 34 are connected to the PCa end beam member 36. It is joined to the joint means 36c inserted in the.

  For example, in the case of the third embodiment, the intermediate column PCa joint member 25 is heavier than the PCa column member 22a and the PCa beam member 24 because the beam portions 25b are integrally formed in four directions along the XY direction. However, as in this embodiment, the PCa joint member 35 is configured to constitute only a part of the column 32, and the PCa end beam member 36 constituting a part of the large beam 33 is divided into separate members. Thus, the maximum weight of the PCa member can be reduced, and the reinforced concrete structure 31 can be constructed with a smaller lifting equipment. Conversely, even if the same lifting equipment is used, the reinforced concrete structure 31 having a larger cross-sectional dimension or span of the large beam 33 can be constructed.

  This is the end of the description of specific embodiments, but the present invention is not limited to these embodiments. For example, in the above-described embodiment, the PCa column member or the PCa joint member is used, but all or a part of these may be spot-cast concrete. Moreover, in the said 3rd and 4th embodiment, although the big beam was divided into 3 in the longitudinal direction, it is good also as a form which makes a division | segmentation only one and divides a large beam into 2 in the longitudinal direction. In addition to these changes, the specific shape and number of the PCa beam members can be appropriately changed as long as they do not depart from the spirit of the present invention.

1, 11, 21, 31 Reinforced concrete structure 2, 12, 22, 32 Column 2a, 12a, 22a, 32a PCa column member 3, 13, 23, 33 Large beam 4, 24, 34 PCa beam member 14 Long-term load beam member 15 Beam member for seismic load 23, 25 PCa joint member 23M Central beam portion 25a Column portion 25b Beam portion 36 PCa end beam member

Claims (9)

A reinforced concrete structure having a pair of columns and a precast concrete beam having both ends joined to the pair of columns,
The precast concrete beam is composed of a plurality of precast concrete beam pieces divided in the width direction.   2. The reinforced concrete structure according to claim 1, wherein the plurality of precast concrete beam pieces are cast after construction of a portion to be joined to a slab. 3.   The said precast concrete beam has at least one precast concrete beam piece for seismic load which is not joined to a slab, and at least one precast concrete beam piece for long-term load which is joined to a slab. Or the reinforced concrete structure of Claim 2.   4. The reinforced concrete structure according to claim 3, wherein the precast concrete beam piece for long-term load is joined to the column at both ends only. 5.   The reinforced concrete structure according to claim 1 or 2, wherein at least one of the plurality of precast concrete beam pieces has different cross-sectional performance with respect to the other.   The reinforced concrete structure according to claim 1, wherein post tension is applied to at least one of the plurality of precast concrete beam pieces. A reinforced concrete structure having a pair of columns and a beam having both ends joined to the pair of columns,
The beam is divided into three in the longitudinal direction, and has a central beam portion located at the center and two end beam portions located at both ends,
The central beam portion is composed of a plurality of precast concrete beam pieces divided in the width direction.   The reinforced concrete structure according to claim 7, wherein at least one of the end beam portions is made of precast concrete formed integrally with the column.   8. The reinforced concrete structure according to claim 7, wherein at least one of the end beam portions is made of precast concrete formed separately from the pillar.

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