Methods for constructing columns or beams and column-beam joint structures

Abstract

This invention provides a method for constructing columns and beams using precast concrete (PCa) members, even if the length of the PCa members does not match the length of the columns and beams. [Solution] A method for constructing a column 72 or beam 73 comprises the steps of selecting a first precast concrete member 16, preparing a second precast concrete member 74, transporting these precast concrete members, and pressing these precast concrete members together at the construction site. The second member 74 is designed or selected to compensate for the difference between the length of the first member 16 in the extending direction and the length of the beam 73.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a method for constructing a column or a beam using a precast concrete member and a tension member, and a column-beam joint structure.

Background Art

[0002] For example, as shown in Patent Documents 1 and 2, an unbonded precast prestressed concrete method (hereinafter referred to as the "unbonded PCaPC method") is known as a method for constructing a building. In the unbonded PCaPC method, precast concrete members (hereinafter, "precast concrete" is referred to as "PCa") are pressure-bonded to each other by an unbonded tension member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a building constructed by the unbonded PCaPC method, since there is no adhesion between the tension member and the concrete, the PCa member used as a column or a beam can be easily removed, and it becomes easy to reuse (recycle) the PCa member. However, since the lengths of columns and beams vary for each building, in order to reuse the PCa member, it is necessary to store several types of disassembled PCa members and be able to select the PCa member to be reused from them, or to adjust the demolition time of the building having the PCa member and the construction time of the building where the PCa member is planned to be reused.

[0005] One possible solution to these problems is to standardize precast concrete (PCa) members into unified components. If components are standardized, the same formwork can be reused during manufacturing, leading to cost reductions. However, standardizing PCa members necessitates selecting column and beam lengths to match the PCa members, reducing the design flexibility of the building. Furthermore, depending on building conditions and client requirements, it may be necessary to design columns and beams to lengths different from those of standardized PCa members.

[0006] In view of the above background, the present invention aims to provide a method for constructing columns and beams using precast concrete (PCa) members, even if the length of the PCa members does not match the length of the columns and beams. [Means for solving the problem]

[0007] To solve the above problems, one aspect of the present invention provides a method for constructing a second load-bearing section between a pair of first load-bearing sections that constitute one of a column (72, 102) and a beam (73, 82, 92), the second load-bearing section constituting the other of the column and the beam, comprising the steps of: selecting a first precast concrete member (16, 46, 83) having a specified length in the extending direction of the second load-bearing section; preparing a second precast concrete member (74, 85, 93, 103) that cooperates with the first member to form the second load-bearing section; transporting the first member and the second member to a construction site; and at the construction site, positioning the first member and the second member at the location where they are to be installed, and using a tensioning member (19) to tension the first member and the second member The method comprises the steps of pressing members together, wherein one of the first member and the second member is a column-beam joint member (74, 83, 93, 103), the column-beam joint member includes a projection (75, 84, 94, 104) that protrudes toward the second member beyond the surface of the first load-bearing portion and forms part of the second load-bearing portion, the total length in the extending direction of the portion of one or more of the first members located between the opposing surfaces of a pair of the first load-bearing portions is shorter than the distance between the surfaces of the pair of first load-bearing portions, and the step of preparing the second member includes setting the length in the extending direction of the portion of the second member located between the surfaces of the pair of first load-bearing portions to compensate for the difference between the total length and the distance.

[0008] According to this embodiment, since the length of the second load-bearing section can be adjusted by the second member, the second load-bearing section can be constructed using the first member having a predetermined length.

[0009] In the above embodiment, the first member (16, 46, 83) may be a precast concrete member that was used in an existing building.

[0010] According to this embodiment, existing column or beam members of a building that are shorter than the length of the target column or beam can be reused.

[0011] In the above embodiment, the first member (16, 33, 83) may be a precast concrete column member or beam member designed as a standard or general-purpose product.

[0012] According to this embodiment, standard or general-purpose precast concrete (PCa) column or beam members that are shorter than the length of the target column or beam can be used. By using standard or general-purpose PCa members, the manufacturing cost of the PCa members can be reduced.

[0013] In the above embodiment, the tensioning member (19) may be used in an unbonded state.

[0014] According to this embodiment, the precast concrete (PCa) members, which are pressed together by an unbonded tensioning material, separate during an earthquake, thereby suppressing damage to the PCa members.

[0015] In the above embodiment, the second member (74, 93, 103) is the column-beam joint member, one of the first members (16, 46) is arranged between a pair of the first load-bearing parts (42, 72), and the length of the protruding part (75, 94, 104) in the extending direction may be shorter than the length of the first member in the extending direction.

[0016] According to this embodiment, among the portions joined by the unbonded tensioning material, a relatively large load is applied to the portion of the second load-bearing section that is close to the surface of the first load-bearing section, thus further suppressing damage to the first member.

[0017] In the above embodiment, the first member (16) includes an intermediate portion (21) positioned in the middle of the extending direction and a widened end portion (22) positioned at the end of the extending direction and wider than the intermediate portion in a direction perpendicular to the extending direction, and the tensioning member (19) may be fixed to the widened portion of the widened end portion.

[0018] In this configuration, since tension can be introduced to each column-beam joint structure, even if a tensioning member is cut, the repair scope is limited to that column-beam joint structure. [Effects of the Invention]

[0019] According to the above aspect, even if the length of the PCa member does not match the length of the column or beam, a method of constructing a column or beam using the PCa member can be provided.

Brief Description of the Drawings

[0020] [Figure 1] Perspective view showing the framework of a building according to the first embodiment [Figure 2] (A) Front view of an existing beam and column-beam joint structure, (B) Front view of a beam and column-beam joint structure according to the first embodiment [Figure 3] Perspective view of a column-beam joint structure according to the first embodiment [Figure 4] View showing a model of a beam according to the first embodiment [Figure 5] Front view of a beam and column-beam joint structure according to the second embodiment [Figure 6] Front view of a column and column-beam joint structure according to the third embodiment [Figure 7] Front view of a column and column-beam joint structure according to the fourth embodiment [Figure 8] (A) View showing a cross-section taken along line VIIIA-VIIIA in FIG. 7 with the beam omitted, (B) The same cross-section in a modified example [Figure 9] Front view of a column and column-beam joint structure according to the fifth embodiment [Figure 10] Front view of a column and column-beam joint structure according to the sixth embodiment [Figure 11] Front view of a column and column-beam joint structure according to the seventh embodiment [Figure 12] Front view of a column and column-beam joint structure according to the eighth embodiment [Figure 13] Front view of a column and column-beam joint structure according to the ninth embodiment

Modes for Carrying Out the Invention

[0021] Several embodiments of the present invention will be described in detail below with reference to the drawings. The present invention is applicable to reinforced concrete or steel-reinforced concrete frame structure buildings. ≪First Embodiment≫

[0022] First, a first embodiment of the present invention will be described with reference to Figures 1 to 4. Figure 1 is a perspective view showing the framework of a building 1 according to the first embodiment. As shown in Figure 1, the building 1 is equipped with a pile foundation 2. The pile foundation 2 is equipped with a plurality of piles 3 arranged in the X direction (length direction) and Y direction (width direction) perpendicular to each other on the horizontal plane. The building 1 is also equipped with a superstructure 10 that is constructed on top of the pile foundation 2 and supported by the pile foundation 2. The superstructure 10 is equipped with a plurality of columns 11 provided at positions corresponding to the piles 3, and a plurality of beams 12 that connect pairs of columns 11 adjacent to each other in the X direction or Y direction.

[0023] The column 11 includes a precast concrete (PCa) column member 13. In this embodiment, the column 11 of the first floor is formed by one column member 13, but the column 11 of the first floor may be formed by two or more PCa members.

[0024] Figure 2(A) is a front view showing a beam 212 and a column-beam joint structure 214 in an existing building 201, and Figure 2(B) is a front view showing a beam 12 and a column-beam joint structure 14 according to the first embodiment. As shown in Figures 1 and 2(B), a PCa column-beam joint member 15 is provided at the portion of the column 11 that connects to the beam 12, positioned between two column members 13 that are aligned vertically. The column-beam joint member 15 is a reinforced concrete member that is generally rectangular in shape, and has an outer contour that substantially coincides with the outer contour of the adjacent column member 13 in a plan view, and has an outer contour that substantially coincides with the outer contour of the adjacent portion of the beam 12 when viewed from the direction of extension of the beam 12.

[0025] Figure 3 is a perspective view showing a column-beam joint structure 14. As shown in Figures 1, 2(B), and 3, each beam 12 includes a first precast concrete beam member 16 positioned between a pair of adjacent columns 11, a second precast concrete beam member 17 positioned between the column-beam joint member 15 and the first beam member 16, a joint material 18 provided between the first beam member 16 and the second beam member 17, and between the column-beam joint member 15 and the second beam member 17, a tensioning member 19 that presses the first beam member 16 against the column-beam joint member 15 via the second beam member 17 and the joint material 18, and a fixing device 20 that fixes the tensioning member 19 to the first beam member 16.

[0026] As shown in Figure 2(A), the existing building 201 includes a pair of columns 211 and a beam 212 spanning between the pair of columns 211. Each column 211 includes a column member 213 and a column-beam joint member 215 positioned at the point where the beam 212 connects to the column 211. The column member 213 and the column-beam joint member 215 may have the same configuration as the column member 13 and column-beam joint member 15 of the first embodiment (see Figure 2(B)). The beam 212 includes a precast concrete beam member 216 positioned between the pair of columns 211 and pressed against the column-beam joint member 215 via a joint member 218 by a tensioning member 219. The beam member 216 has the same configuration as the first beam member 16 of the first embodiment.

[0027] As shown in Figures 2(A) and (B), when considering the reuse of the beam member 216, a problem arises in that the length of the beam 12 in the first embodiment (the distance between the opposing surfaces of a pair of columns 11) is longer than the length of the beam 212 of the existing building 201. To solve this problem, in the first embodiment, not only is the beam member 216 used as the first beam member 16, but the difference in length is compensated by using a second beam member 17. Note that a precast concrete (PCa) member designed as a standard or general-purpose product may be used as the first beam member 16. In other words, this embodiment is applied when the length of the beam 12 is longer than the length to which one standard or general-purpose PCa member fits, and the second beam member 17 compensates for the difference in length.

[0028] As shown in Figures 1, 2(B), and 3, the first beam member 16 is a variable cross-section beam including an intermediate section 21 positioned in the middle of its extending direction and widened ends 22 positioned at both ends of its extending direction and wider than the intermediate section 21 in the beam width direction. The first beam member 16 is a reinforced concrete member including a plurality of main reinforcements 23 extending in the extending direction of the first beam member 16 and a plurality of shear reinforcements (not shown) positioned perpendicular to the main reinforcements 23 and surrounding the plurality of main reinforcements 23. The shape of the cross section perpendicular to the extending direction in the intermediate section 21 is rectangular, and this shape may be the same at any point in the extending direction. Each of the pair of widened ends 22 has a rectangular cross-sectional shape in the cross section perpendicular to the extending direction and, being wider than the intermediate section 21, has a shoulder surface 24 facing inward in the extending direction. The beam depth of the widened ends 22 may be the same as the beam depth of the intermediate section 21. The pair of widened ends 22 are preferably mirror-symmetric with respect to a plane perpendicular to the extending direction that passes through the center of the extending direction of the first beam member 16. The first beam member 16 may be, for example, a prestressed concrete member in which tension is introduced along its entire length in the extending direction.

[0029] The second beam member 17 has an outer contour that substantially coincides with the outer contour of the widened end 22 of the first beam member 16 and the outer contour of the column-beam joint member 15 when viewed from the extending direction of the first beam member 16. The second beam member 17 is made of unreinforced concrete or reinforced concrete including shear reinforcement bars (not shown). The second beam member 17 has through holes (not shown) that extend in the extending direction of the first beam member 16 and align with the main reinforcement bars 23 of the first beam member 16. Mechanical anchoring hardware 25 is attached to the ends of the main reinforcement bars 23 of the first beam member 16. Preferably, the length of the second beam member 17 in the extending direction of the beam 12 is shorter than the length of the first beam member 16 in the extending direction. Preferably, the second beam member 17 has lower rigidity than the first beam member 16, and therefore, in the event of an earthquake of a certain magnitude or greater, it is more easily deformed than the first beam member 16, and damage is concentrated thereon. In the illustrated example, one second beam member 17 is placed between the extending ends of the first beam member 16 and the column-beam joint member 15. However, multiple second beam members 17 may be placed at each location so as to be aligned in the extending direction of the first beam member 16, or they may be placed only on one side of the extending direction relative to the first beam member 16. When increasing the length of the second beam member 17 in the extending direction, the second beam member 17 may include main reinforcement (not shown).

[0030] The joint material 18 is formed by mortar or the like. The joint material 18 is used to absorb unevenness in the concrete surface of the column-beam joint member 15, the first beam member 16, and the second beam member 17, as well as construction errors.

[0031] A through-hole 22a is provided along the extending direction of the beam 12 in the portion of the widened end 22 of the first beam member 16 that is wider than the intermediate portion 21, that is, the portion located outward in the beam width direction from the surface of the intermediate portion 21 in the beam width direction. Through-holes 15a and 17a are provided in the column-beam joint member 15 and the second beam member 17 at positions that align with the through-hole 22a of the widened end 22. The through-holes 15a, 17a, and 22a are formed, for example, by a sheath. The tensioning member 19 is inserted through the through-hole 15a of the column-beam joint member 15, as well as the through-holes 22a of the widened ends 22 of the first beam member 16 on both sides and the through-holes 17a of the second beam member 17 on both sides. The anchoring device 20 anchors both ends of the tensioning member 19, which is inserted through the through-holes 15a, 17a, and 22a and to which tension is applied, to the shoulder surface 24 of the widened end 22 of the first beam member 16. The tensioning member 19 is used in an unbonded state, that is, without filling material such as grout in the through holes 15a, 17a, and 22a. In this case, the first beam member 16 can be removed from the column-beam joint member 15 and the second beam member 17 by removing the anchoring device 20 and releasing the tension of the tensioning member 19, making it easy to reuse. If reuse of the first beam member 16 is not required, the tensioning member 19 may be used in a bonded state, that is, with filling material such as grout in the through holes 15a, 17a, and 22a. The tensioning member 19 is, for example, a PC steel bar, PC steel wire, PC steel strand, or a fiber-reinforced plastic member such as aramid fiber, carbon fiber, or glass fiber.

[0032] Figure 4 shows a model of beam 12. As shown in Figures 2(B) and 4, in the modeled beam 12, the portion where the column-beam joint member 15 and the second beam member 17 are pressed together via the joint material 18, and the portion where the second beam member 17 and the first beam member 16 are pressed together via the joint material 18, are each represented as a bending spring 26. This is because, by using the tensioning member 19 in an unbonded state, the members that are pressed together can separate from each other during an earthquake. In addition, the portion in the first beam member 16 where the cross-section changes, i.e., the boundary portion between the intermediate portion 21 and the widened end portion 22, is also represented as a bending spring 26. The portion represented as a bending spring 26 in this way functions as a plastic hinge during an earthquake of a predetermined magnitude or greater. The magnitude of the relative displacement between the bending spring 26 at the boundary portion between the intermediate portion 21 and the widened end portion 22 and the bending spring 26 at the portion where the members are pressed together can be adjusted by design.

[0033] The construction method for the beam 12 and column-beam joint structure 14 will be explained with reference to Figures 1 to 3. The constructor confirms the required length of the beam 12 (the distance between the opposing surfaces of the pair of columns 11 on which the beam 12 is placed) and its strength. If there is no existing, standard, or general-purpose beam member 216 that has the required strength and a length that approximately matches the length of the beam 12 when combined with the thickness of the joint material 18, the constructor will consider applying this embodiment. The constructor selects a first beam member 16 from among the existing, standard, or general-purpose beam members 216 that has the required strength and an extending length shorter than the required length of the beam 12.

[0034] Next, the constructor sets the length of the second beam member 17 in the extending direction of the beam 12. In this embodiment, since two second beam members 17 are provided for one first beam member 16, the length of the second beam member 17 is half the length of the beam 12 minus the extending length of the first beam member 16 and the thickness of the joint material 18. The constructor manufactures the column-beam joint member 15 and the second beam member 17 at a PCa factory. Alternatively, the constructor may design and manufacture multiple types of column-beam joint members 15 and / or second beam members 17 with different dimensions as standard or general-purpose products, select a column-beam joint member 15 and / or second beam member 17 with appropriate dimensions from among them, and make fine adjustments to the length by adjusting the thickness of the joint material 18 as needed.

[0035] Next, the constructor transports the first beam member 16, the second beam member 17, and the column-beam joint member 15 to the construction site of building 1.

[0036] The constructor uses a lifting machine (not shown) at the construction site to position the column-beam joint member 15, the first beam member 16, and the second beam member 17 in the locations where they should be installed. The constructor injects joint material 18 between the column-beam joint member 15 and the second beam member 17, and between the first beam member 16 and the second beam member 17. After the joint material 18 hardens, the constructor inserts tensioning members 19 through the widened end 22 of the first beam member 16, the through holes 22a, 17a, and 15a of the second beam member 17 and the column-beam joint member 15, tensions the tensioning members 19, and uses fixing devices 20 to fix both ends of the tensioning members 19 to the shoulder surfaces 24 of the widened end 22. This introduction of tension causes the first beam member 16 to be pressed against the column-beam joint member 15 via the second beam member 17 and the joint material 18.

[0037] When this building 1 is demolished and the first beam member 16 is to be reused, workers release the tension of the tensioning member 19 to separate the first beam member 16 from the column-beam joint member 15 and the second beam member 17, and then lower the first beam member 16 using a lifting machine. The first beam member 16 becomes reusable through this process and is transported to the reuse location or storage location.

[0038] The effects of the first embodiment will now be described. Since the length of the beam 12 is adjusted by the second beam member 17, a first beam member 16 having a shorter extending length than the length of the beam 12 can be used as one of the members constituting the beam 12. For this reason, a precast concrete beam member 216 used in the existing building 201, or a standard or general-purpose precast concrete member can be used as the first beam member 16. Furthermore, since the length of the beam 12 can be changed by the second beam member 17, even if the design condition is to use a first beam member 16 of a predetermined length, the length of the beam 12 can be freely set, and the degree of design freedom is not impaired.

[0039] The second beam member 17 is located at the end of the beam 12, where it is subjected to relatively large loads during an earthquake, and is therefore more susceptible to damage than the first beam member 16 during an earthquake. Furthermore, the second beam member 17 is also more susceptible to damage than the first beam member 16 during an earthquake because it has lower rigidity than the first beam member 16. Even if the second beam member 17, which constitutes the end of the beam 12, collapses, the first beam member 16 remains intact, and therefore the scope of repair is limited to its column-beam joint structure 14. Even if the second beam member 17 is damaged, the cost of replacing the damaged member is reduced because the second beam member 17 is smaller than the first beam member 16.

[0040] Even if multiple second beam members 17 are provided between the column-beam joint member 15 and the first beam member 16, tensioning the tensioning member 19 will cause all second beam members 17 positioned between the column-beam joint member 15 and the first beam member 16 to be pressed against and fixed to the adjacent members. Therefore, even if there are multiple second beam members 17, no special work is required. Since the second beam members 17 are fixed by compression, even if the second beam members 17 are made of reinforced concrete, the amount of reinforcement required is kept to a minimum.

[0041] If the second beam member 17 is made smaller than the calculated crack width interval, no cracks will occur in the second beam member 17, and therefore the second beam member 17 can be reused.

[0042] One reason why the reuse of precast concrete (PCa) members has been avoided is their weight. In this embodiment, since the beam 12 is composed of multiple PCa members (first beam member 16 and second beam member 17), the PCa members can be made smaller compared to the size of the beam 12. This allows for a smaller lifting machine, thereby reducing construction costs. When there is a large weight difference between one first beam member 16 and one second beam member 17, lifting multiple relatively lighter second beam members 17 simultaneously to the construction floor with a lifting machine reduces the number of lifting operations required, leading to a reduction in carbon dioxide emissions and construction time.

[0043] The relatively small second beam member 17 can be placed in the gap left after the column member 13, column-beam joint member 15, and / or first beam member 16 have been loaded onto the transport vehicle during transportation, thus improving transportation efficiency.

[0044] If a single beam member 216 substantially constitutes a single beam 212, the beam 212 may bend (undergo bending deformation) during an earthquake, potentially causing bending cracks in the beam 212. In this embodiment, the beam 12 has a structure in which several concrete blocks (first beam member 16 and second beam member 17) are compressed together by an unbonded tensioning member 19. As a result, joints are provided between each block, and when subjected to an earthquake, these joints open (separate), making it less likely for bending cracks to occur. After the earthquake, the compression force of the unbonded tensioning member 19 returns the beam 12 to its original shape and position. Therefore, no residual deformation remains in the beam 12, and the beam 12 has high reusability after an earthquake.

[0045] ≪Second Embodiment≫ A second embodiment of the present invention will be described with reference to Figure 5. In the description, components common to previously described embodiments will be omitted from the description and given the same reference numerals, while similar components will only be described for their differing parts and given the same reference numerals (the same applies to the description of the third embodiment and subsequent embodiments). Figure 5 is a front view showing a column-beam joint structure 31 and a beam 32 according to the second embodiment. The column-beam joint structure 31 according to the second embodiment includes two column members 13 arranged vertically, a column-beam joint member 15 arranged between the two column members 13, and a beam 32 joined to the column-beam joint member 15.

[0046] The beam 32 spans between a pair of adjacent columns 11. The beam 32 includes a first precast concrete beam member 33 positioned between the pair of columns 11, a second precast concrete beam member 17 positioned between the column-beam joint member 15 and the first beam member 33, joint members 18 provided between the first beam member 33 and the second beam member 17, and between the column-beam joint member 15 and the second beam member 17, tensioning members 19 that press the first beam member 16 against the column-beam joint member 15 via the second beam member 17 and the joint members 18, and fixing devices 20 (see Figure 3) that fix the tensioning members 19 to the column-beam joint member 15.

[0047] The first beam member 33 is a reinforced concrete PCa member having a fixed rectangular cross-sectional shape along its extending direction. Similar to the first beam member 16 of the first embodiment, the first beam member 33 includes main reinforcement bars 23 (see Figure 3), shear reinforcement bars (not shown), and mechanical anchoring hardware 25. The first beam member 33 has through holes (not shown) that extend along its entire length in its extending direction through which tensioning members 19 are inserted.

[0048] The tensioning members 19 differ from those in the first embodiment in their arrangement. They are inserted through the through-holes in the first beam member 33, the through-holes 17a in the pair of second beam members 17 (see Figure 3), and the through-holes in the pair of column-beam joint members 15 (see Figure 3). Both ends of the tensioning members 19 are fixed by the anchoring devices 20 (see Figure 3) to the concrete surface on the side of the corresponding column-beam joint member 15 opposite to the side to which the first beam member 33 is pressed. In the illustrated example, each tensioning member 19 presses one first beam member 33 to the column-beam joint members 15 arranged on both sides in its extending direction via the second beam member 17 and the joint material 18. However, each tensioning member 19 may be arranged over multiple spans to press multiple first beam members 33 to the column-beam joint members 15.

[0049] The column-beam joint structure 31 and beam 32 of the second embodiment can be constructed in the same manner as the first embodiment, although the arrangement of the tensioning members 19 is changed. Furthermore, the second embodiment has the same effects as the first embodiment, except for the effects of the variable-section beam and the effects of the arrangement of the tensioning members on the variable-section beam. In addition, since the tensioning members 19 apply tension along the entire length of the first beam member 33 in the extending direction, the tensile strength of the first beam member 33 is increased. ≪Third Embodiment≫

[0050] A third embodiment will be described with reference to Figure 6. In the building 41 according to the third embodiment, instead of beams 42, columns 43 use precast concrete members from the existing building 201 or standard or general-purpose precast concrete members. Figure 6(A) is a front view showing columns 211 and column-beam joint structure 214 in the existing building 201, and Figure 6(B) is a front view showing columns 43 and column-beam joint structure 44 according to the third embodiment.

[0051] Beam 42 is constructed similarly to beam 212 of the existing building 201 and includes beam member 216.

[0052] A precast concrete (PCa) column-beam joint member 45 is provided at the portion of the column 43 that connects to the beam 42. The column-beam joint member 45 has the same configuration as the column-beam joint member 15 of the first embodiment, except that a through hole (not shown) for inserting the tensioning member 19 is provided in the vertical direction.

[0053] Each column 43 comprises a first column member 46 made of PCa, positioned between two vertically adjacent column-beam joint members 45, and a second column member 47 made of PCa, positioned above and below the first column member 46, between the column-beam joint member 45 and the first column member 46 (when distinguishing between the upper and lower second column members 47, the one positioned lower will be referred to as second column member 47a, and the one positioned upper as second column member 47b), and between the first column member 46 and the second column member 47, parallel The assembly includes a joint material 18 provided between the column-beam joint member 45 and the second column member 47, a tensioning member 19 that presses the first column member 46 and the second column member 47a positioned below it against each other via the joint material 18, and presses the first column member 46 against the column-beam joint member 45 via the second column member 47b positioned above it and the joint material 18, and a fixing device 20 (see Figure 3) that fixes the tensioning member 19 to the second column member 47 positioned below and the column-beam joint member 45.

[0054] As shown in Figure 6(A), in the existing building 201, the column 11 includes a PCa column member 213 positioned between vertically adjacent column-beam joint members 215 and pressed against the column-beam joint member 215 positioned above it via a joint member 218 by a tensioning member 219. The column member 213 has the same configuration as the first column member 46 in the third embodiment.

[0055] As shown in Figures 6(A) and (B), when considering the reuse of the column member 213, a problem arises in that the length of one floor of the column 43 in the third embodiment (the distance between the upper surface of the lower beam 42 and the lower surface of the upper beam 42) is longer than the length of one floor of the column 11 of the existing building 201. To solve this problem, in the third embodiment, in addition to using the column member 213 as the first column member 46, the difference in length is compensated for by using a second column member 47.

[0056] The first column member 46 is a reinforced concrete member that includes a plurality of main reinforcements (not shown) and a plurality of shear reinforcements (not shown) extending in the vertical direction, which is its direction of extension. The cross-sectional shape of the first column member 46 is rectangular, and this shape may be the same at any point along the direction of extension.

[0057] The second column member 47 has an outer contour that substantially coincides with the outer contour of the first column member 46 and the outer contour of the column-beam joint member 45 when viewed from above. The second column member 47 is made of unreinforced concrete or reinforced concrete including main reinforcement and shear reinforcement (not shown). The main reinforcement of the first column member 46 and the main reinforcement of the second column member 47 are anchored to the concrete by being bent within their respective members. The length of the second column member 47 in the vertical direction is preferably shorter than the length of the first column member 46 in the extending direction. The second column member 47 preferably has lower rigidity than the first column member 46, and therefore is more prone to deformation and breakage than the first column member 46 during earthquakes of a predetermined magnitude or greater. In the illustrated example, one second column member 47 is positioned between the vertical ends of the first column member 46 and the column-beam joint member 45. However, multiple second column members 47 may be arranged vertically at each location, or they may be positioned only on one side of the first column member 46 in the vertical direction. When increasing the vertical length of the second column member 47, the second column member 47 may include main reinforcement bars (not shown) that are connected to the reinforcement bars of the column-beam joint member 45 and the main reinforcement bars of the first column member 46.

[0058] The first column member 46, the second column member 47, and the column-beam joint member 45 are provided with through-holes (not shown) that extend vertically and through which a tensioning member 19 is inserted, aligned vertically with each other. The tensioning member 19 is inserted through the through-holes of the second column member 47a and the first column member 46 located below, the second column member 47b located above, and the column-beam joint member 45 on the upper floor side. With the tensioning member 19 tensioned, the lower end of the tensioning member 19 is fixed to the lower surface of the second column member 47a located below, and the upper end of the tensioning member 19 is fixed to the upper surface of the column-beam joint member 45 on the upper floor side by a fixing device 20 (see Figure 3). The second column member 47b located below has a recess 47c that receives the fixing device 20 fixed to itself and the fixing device 20 fixed to the upper surface of the column-beam joint member 45 located below it. The tensioning member 19 is used in an unbonded state.

[0059] Compared to the first embodiment, the column-beam joint structure 44 and column 43 according to the third embodiment have a different arrangement of tensioning members 19, but can be constructed in the same way as the first embodiment by substituting the first beam member 16 and the second beam member 17 (see Figure 2(B)) with the first column member 46 and the second column member 47. Furthermore, the column 43 and column-beam joint structure 44 of the third embodiment have the same effects and advantages as the beam 12 and column-beam joint structure 14 of the first embodiment. ≪Fourth Embodiment≫

[0060] The column-beam joint structure 51 and column 52 according to the fourth embodiment will be described with reference to Figures 7 and 8. Figure 7 is a front view showing the column-beam joint structure 51 and column 52 according to the fourth embodiment, Figure 8(A) is a diagram showing a cross section along the line VIIIA-VIIIA in Figure 7, with the beam 42 not shown, and Figure 8(B) is a diagram showing a modified example of the same cross section. The fourth embodiment differs from the third embodiment in that the shape of the second column member 53, which is positioned between the upper surface of the first column member 46 and the lower surface of the column-beam joint member 45, differs from the second column member 47b of the third embodiment, but otherwise has a configuration common to the third embodiment.

[0061] Four beam members 216 are joined to the column-beam joint member 45, and in plan view, the column-beam joint structure 51 has a cross shape. The second column member 53, positioned below the column-beam joint member 45, has a side end 53a that protrudes downward toward the beam member 216 from the side of the beam member 216 of the first column member 46 positioned below it and the side of the column-beam joint member 45 positioned above it. The second column member 53 may have its side end 53a provided so as to be able to support the beam member 216, as shown in Figure 8(A), or it may have its side end 53a provided so as to be a cross shape in plan view, as shown in Figure 8(B).

[0062] The column-beam joint structure 51 and column 52 according to the fourth embodiment can be constructed in the same manner as the third embodiment and have the same effects and advantages as the third embodiment. Furthermore, the column-beam joint structure 51 according to the fourth embodiment has the effect of preventing the beam member 216 from falling, even if the tensioning member 219 that presses the beam member 216 to the column-beam joint member 45 is cut, because the second column member 53 positioned below the beam member 216 supports the beam member 216 from below. ≪Fifth Embodiment≫

[0063] Referring to Figure 9, the column-beam joint structure 61 and column 62 according to the fifth embodiment will be described. Figure 9 is a front view showing the column-beam joint structure 61 and column 62 according to the fifth embodiment. The fifth embodiment differs from the fourth embodiment in that the shape of the second column member 63, which is positioned between the upper surface of the first column member 46 and the lower surface of the column-beam joint member 45, is different from that of the second column member 53 of the fourth embodiment, but otherwise has a configuration common to the fourth embodiment.

[0064] In the fourth embodiment, the side end portion 53a (see Figure 7) of the second column member 53 has both an upper and lower surface that protrudes similarly, and its side surface is parallel to the vertical direction. In contrast, in the fifth embodiment, the side end portion 63a of the second column member 63 has an upper surface that protrudes outward and a lower surface that does not protrude, so its side surface is inclined. The column-beam joint structure 61 and column 62 according to the fifth embodiment can be constructed in the same way as the fourth embodiment, even if the second column member 53 has this shape, and has the same effects and advantages as the fourth embodiment. ≪Sixth Embodiment≫

[0065] The column-beam joint structure 71, column 72, and beam 73 according to the sixth embodiment will be described with reference to Figure 10. Figure 10 is a front view showing the column-beam joint structure 71 and beam 73 according to the sixth embodiment. In the first embodiment, the second beam member 17 compensated for the insufficient length of the first beam member 16 in the extending direction (see Figure 2(B)), but in the sixth embodiment, the column-beam joint member 74 compensates for the insufficient length of the first beam member 16 in the extending direction instead of the second beam member 17.

[0066] The column-beam joint member 74 is a single precast concrete (PCa) member that has a shape combining the column-beam joint member 15 and the second beam member 17 (see Figure 2(B)) in the first embodiment. Therefore, the column-beam joint member 74 includes a protruding portion 75 that extends from the side surface of the column member 13 toward the first beam member 16 to which it is joined. In plan view, the column-beam joint member 74 has a rectangular shape when joined to one or two first beam members 16 arranged in opposite directions, an L-shape when joined to two first beam members 16 arranged at a right angle, a T-shape when joined to three first beam members 16, and a cross shape when joined to four first beam members 16.

[0067] The column-beam joint structure 71 and beam 73 according to the sixth embodiment can be constructed by modifying the construction method of the first embodiment so that the column-beam joint member 15 and the second beam member 17 (see Figure 2(B)) in the first embodiment are moved simultaneously as a single unit, which will result in the column-beam joint member 74.

[0068] The sixth embodiment has the same advantages and disadvantages as the first embodiment, in that it allows the use of existing, standard, or general-purpose first beam members 16, allows the length of the beam 73 to be freely set, allows the size of the lifting equipment to be reduced, and the unbonded tensioning member 19 ensures that the beam 73 can be used continuously after an earthquake. ≪Seventh Embodiment≫

[0069] The column-beam joint structure 81 and beam 82 according to the seventh embodiment will be described with reference to Figure 11. Figure 11 is a front view showing the column-beam joint structure 81 and beam 82 according to the seventh embodiment. The column-beam joint structure 81 includes a column-beam joint member 83 joined to a column member 13. Column-beam joint members 83 adjacent to each other in the extending direction of the beam 82 include protruding portions 84 that project toward each other and constitute a part of the beam 82. The column-beam joint members 83 are either reused existing members, standard products, or general-purpose products, and are made of PCa. A PCa beam member 85 is positioned between these two protruding portions 84 to adjust the length of the beam 82, and a joint material 18 is provided between the protruding portions 84 and the beam member 85. In the extending direction of the beam 82, the length of the beam member 85 is set to the length of the beam 82 minus the lengths of the two protruding portions 84 and the thickness of the joint material 18.

[0070] The protruding portion 84 has a widened end 86 on the protruding end side, which has the same configuration as the widened end 22 of the first beam member 16 in the first embodiment (see Figures 2(B) and 3). The widened end 86 has a shoulder surface 87 facing away from the beam member 85. The tensioning member 19 is inserted through the two widened ends 86 and the beam member 85 between them, and the tensioning member 19 is fixed to the shoulder surface 87 by a fixing device 20 (see Figure 3).

[0071] Thus, even if the column-beam joint member 83 is an existing, standard, or general-purpose PCa member, and the length is adjusted by a beam member 85 positioned in the middle of the extending direction of the beam 82, the structure can be constructed in the same manner as the sixth embodiment, except for the arrangement of the tensioning member 19, and the length of the beam 82 can be adjusted. ≪Eighth Embodiment≫

[0072] The column-beam joint structure 91 and beam 92 according to the eighth embodiment will be described with reference to Figure 12. Figure 12 is a front view showing the column-beam joint structure 91 and beam 92 according to the eighth embodiment. The relationship between the eighth embodiment and the second embodiment (see Figure 5) is similar to the relationship between the sixth embodiment (see Figure 10) and the first embodiment (see Figure 2(B)). That is, the column-beam joint member 93 according to the eighth embodiment corresponds to the column-beam joint member 15 and the second beam member 17 of the second embodiment being formed as a single PCa member. Therefore, the column-beam joint member 93 includes a protruding portion 94 that protrudes toward the first beam member 16. Even in this configuration, it can be constructed in the same way as the sixth embodiment, and the length of the beam 92 can be adjusted. ≪Ninth Embodiment≫

[0073] The column-beam joint structure 101 and column 102 according to the ninth embodiment will be described with reference to Figure 13. Figure 13 is a front view showing the column-beam joint structure 101 and column 102 according to the ninth embodiment. The relationship between the ninth embodiment and the third embodiment (see Figure 6) is similar to the relationship between the sixth embodiment (see Figure 10) and the first embodiment (see Figure 2(B)). That is, the column-beam joint member 103 according to the ninth embodiment corresponds to the column-beam joint member 45 and the second column member 47 of the third embodiment being formed as a single PCa member. Therefore, the column-beam joint member 103 includes a projection 104 that protrudes toward the first column member 46. Even in this configuration, the length of the column 102 can be adjusted by setting the length of the projection 104.

[0074] The column-beam joint structure 101 and column 102 according to the ninth embodiment can be constructed by modifying the construction method of the third embodiment so that the column-beam joint member 45 and the second column member 47 (see Figure 6) in the third embodiment are moved simultaneously as a single unit, which will result in the column-beam joint member 103.

[0075] The ninth embodiment has the same advantages and disadvantages as the third embodiment, in that it allows the use of existing, standard, or general-purpose first column members 46, allows the length of the column 102 to be freely set, allows the size of the lifting machine to be reduced, and the unbonded tensioning member 19 ensures that the column 102 can be used continuously after an earthquake.

[0076] This concludes the description of specific embodiments, but the present invention is not limited to the above embodiments or modifications and can be broadly modified and implemented. Embodiments relating to beam length adjustment and embodiments relating to column length adjustment may be combined. The seventh embodiment, in which the length is adjusted in the middle of the load-bearing section, may also be applied to column length adjustment. The widened end of a variable-section beam, in which tension members are fixed to the shoulder surface, may be widened in the vertical direction instead of or in addition to the beam width direction, and tension members may be inserted through the widened portion. [Explanation of Symbols]

[0077] 72,102: Pillar 73,82,92:Beam 13: Pillar member 71,81,91,101: Column beam joint structure 74,93,103: Column-beam joint member (second member) 83: Column-beam joint member (first member) 16: First beam member (first member) 19: Tensile material 21: Middle section 22: Widened end 46: First column member (first member) 75,84,94,104:Protrusion 85: Beam member (second member)

Claims

1. A method for constructing a second load-bearing part that constitutes the other of a column and a beam between a pair of first load-bearing parts that constitute one of the column and the beam, The steps include selecting a first member made of precast concrete having a specified length in the extending direction of the second load-bearing portion, The steps include: preparing a second member made of precast concrete that cooperates with the first member to form the second load-bearing part; A step of transporting the first member and the second member to the construction site, The construction site includes the steps of positioning the first member and the second member at the location where they are to be installed, and pressing the first member and the second member together with a tensioning member, One of the first member and the second member is a column-beam joint member, and the column-beam joint member includes a projection that protrudes toward the second member from the surface of the first load-bearing portion and forms a part of the second load-bearing portion. The total length in the extending direction of the portions located between the opposing surfaces of a pair of first load-bearing portions in one or more of the first members is shorter than the distance between the surfaces of the pair of first load-bearing portions. A method for preparing the second member, comprising setting the length in the extending direction of the portion of the second member located between the surfaces of a pair of first load-bearing portions so as to compensate for the difference between the total length and the distance.

2. The method according to claim 1, wherein the first member is a precast concrete member that was used in an existing building.

3. The method according to claim 1, wherein the first member is a precast concrete member designed as a standard or general-purpose product.

4. The method according to claim 1 or 2, wherein the tensioning material is used in an unbonded state.

5. The second member is the column-beam joint member, One of the first members is arranged between a pair of the first load-bearing parts. The method according to claim 4, wherein the length of the protruding portion in the extending direction is shorter than the length of the first member in the extending direction.

6. The first member includes an intermediate portion located in the middle of the extending direction and a widened end portion located at the end of the extending direction, which is wider than the intermediate portion in a direction perpendicular to the extending direction. The method according to claim 1, wherein the tensioning member is fixed to the widened portion at the widened end.

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