Beam construction method

Abstract

To make it possible to adopt a joint form which is simple as a joint form while reducing the number of joint places where precast beam members are joined with each other, and to achieve improvement in workability and reduction in cost.SOLUTION: In a beam construction method where concrete 3 is cast on a precast beam member 2 where a cross sectional shape is a concave shape and a beam 1 is constructed, the beam 1 is made to be a flat beam whose beam width is wider than a column width. The precast beam member 2 is divided in a beam width direction, and a length of the precast beam member 2 in a beam length direction is set to be a length corresponding to a column span. In a joint part of the precast beam members 2, as a joint form of a lower end main reinforcement 62, a gap-lapped joint is adopted where a joint reinforcement 81 is placed at an upper part of the precast beam member 2 and the lower end main reinforcement 62 does not come into contact with the joint reinforcement 81.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a beam construction method for constructing a beam by placing concrete on a precast beam member.

Background Art

[0002] As the above-described beam construction method, there is provided a precast beam member having a concave shape in which the upper side of the central portion in the beam width direction is open, and a beam construction method is known in which reinforcement such as upper main reinforcement is arranged above the concave portion of the precast beam member and concrete is placed (see, for example, Patent Document 1).

[0003] The beam constructed by the beam construction method described in this Patent Document 1 is formed in a flat shape in which the beam width is larger than the column width. In such a flat beam, due to the weight of the precast beam member and the like, it must be divided into a plurality of parts in the length direction of the beam, and the number of divisions also increases. Therefore, the number of joint portions for joining the precast beam members increases, leading to deterioration of workability and cost increase.

[0004] Therefore, for example, it is conceivable to divide the beam in the beam width direction (see, for example, Patent Document 2). By dividing the beam in the beam width direction in this way, the length of the precast beam member can be increased, and the number of joint portions for joining the precast beam members can be reduced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Document 2, by dividing the beam in the beam width direction, the number of joint portions for joining precast beam members can be reduced. However, when joining precast beam members, for example, if a mechanical joint is adopted as the joint form of the lower end main reinforcement of the precast beam member, it causes deterioration of workability and also leads to cost increase, and there was room for improvement.

[0007] In view of this situation, the main problem of the present invention is to provide a beam construction method that can adopt a simple joint form as the joint form while reducing the number of joint portions for joining precast beam members, and can improve workability and reduce costs.

Means for Solving the Problems

[0008] The first characteristic configuration of the present invention is in a beam construction method of constructing a beam by placing concrete on a precast beam member having a concave cross-sectional shape, the beam is a flat beam having a beam width larger than the column width, the precast beam member is divided in the beam width direction, the length of the precast beam member in the beam length direction is set to a length corresponding to the column span, at the joint portion between the precast beam members, as the joint form of the lower end main reinforcement, a space-overlapping joint is adopted in which a joint bar is placed on the upper part of the precast beam member so that the lower end main reinforcement and the joint bar do not contact each other.

[0009] According to this configuration, since the precast beam member is divided in the beam width direction, the number of divisions of the precast beam member in the beam length direction can be reduced within the weight limit range, and the joint locations where the precast beam members are joined to each other can be reduced. Moreover, since the length of the precast beam member in the beam length direction is set to a length corresponding to the column span, the joint locations of the precast beam members can be made to coincide with the end locations of the column span that become the compression region with respect to the long-term load. As a result, as a joint form of the lower main reinforcement of the precast beam members, a free-lap joint in which a joint bar is placed on the upper part of the precast beam member and the lower main reinforcement and the joint bar do not come into contact can be adopted, so that the joint method can also be simplified.

[0010] From the above, not only can the joint locations of the precast beam members be reduced, but also a simple joint method can be adopted, so that the workability can be improved and the cost can be reduced.

[0011] The second characteristic configuration of the present invention is that the beam is divided into two divided beams in the beam width direction, Each of the two divided beams has a lower main reinforcement and an upper main reinforcement extending in the beam length direction, and a stirrup bar disposed in a state of winding the lower main reinforcement and the upper main reinforcement in a direction orthogonal to the beam length direction, At the column-corresponding location corresponding to the column in the beam length direction, the stirrup bars in each of the two divided beams are formed to be narrow in the beam width direction and are disposed on the outer side of the column.

[0012] According to this configuration, since each of the two divided beams divided in the beam width direction has a lower main reinforcement, an upper main reinforcement, and a stirrup bar, each of the two divided beams can be designed as a structural beam. Therefore, operations such as winding the two divided beams with a single stirrup bar are unnecessary, and for example, a flat beam can be configured with good workability simply by arranging the two divided beams side by side in the beam width direction.

[0013] In such a flat beam, the beam exists on the outer side of the column in the beam width direction at the column corresponding position in the beam length direction. However, according to this configuration, the stirrup bars are formed to be narrow in the beam width direction and arranged on the outer side of the column. Therefore, the stirrup bars can be appropriately arranged even at the column corresponding position to perform shear reinforcement, and a suitable split beam can be constructed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying out the Invention

[0015] An embodiment of the beam construction method according to the present invention will be described with reference to the drawings. As shown in FIG. 5, this beam construction method is a beam construction method for constructing an RC beam 1 by placing concrete 3 on a precast beam member 2 having a concave cross-sectional shape. As shown in FIG. 1, a plurality of beams 1 are provided at intervals in the beam width direction X. In the beam length direction Y, a plurality of columns 4 are arranged at intervals with a predetermined column span A, and each of the plurality of beams 1 is provided in a state extending across the plurality of columns 4 in the beam length direction Y.

[0016] As shown in FIG. 3, the beam 1 is provided as a flat (rectangular) beam 1 having a cross-sectional shape in the beam length direction Y with a beam width B1 larger than the column width B2. As shown in FIG. 5, the beam 1 is divided into two split beams, a first split beam 11 and a second split beam 12, in the beam width direction X. Since the first split beam 11 and the second split beam 12 are basically configured in the same manner, the following description will omit the same configurations.

[0017] As shown on the left side of Fig. 5, the first split beam 11 has a first precast beam member 21, a first lower main reinforcement bar 62 and a first upper main reinforcement bar 61 extending in the beam length direction Y, and a first stirrup bar 63 arranged in a state of winding the first lower main reinforcement bar 62 and the first upper main reinforcement bar 61 in the beam width direction X. Similarly to the first split beam 11, as shown on the right side of Fig. 5, the second split beam 12 has a second precast beam member 22, a second lower main reinforcement bar 72 and a second upper main reinforcement bar 71, and a second stirrup bar 73.

[0018] As shown in Fig. 5, the first precast beam member 21 and the second precast beam member 22 are obtained by splitting the precast beam member 2 with a concave cross-sectional shape in the beam width direction X. The first precast beam member 21 has a first beam width part 21a extending in the beam width direction X and a first upper and lower part 21b extending upward from the outer end of the first beam width part 21a, and is formed in an L-shaped cross-sectional shape. Similarly to the first precast beam member 21, the second precast beam member 22 has a second beam width part 22a and a second upper and lower part 22b, and is formed in an L-shaped cross-sectional shape.

[0019] As shown in Fig. 5, the first lower main reinforcement bar 62 is provided in a state of being embedded in the first precast beam member 21, and the middle part of the first stirrup bar 63 is embedded in the first precast beam member 21, and both end parts thereof are provided in a state of protruding upward from the first precast beam member 21. The second lower main reinforcement bar 72 is provided in the same manner as the first lower main reinforcement bar 62, and the second stirrup bar 73 is provided in the same manner as the first stirrup bar 63. As shear reinforcement bars, a core bar 83 hooked to the first lower main reinforcement bar 62 and the first upper main reinforcement bar 61, and a core bar 83 hooked to the second lower main reinforcement bar 72 and the second upper main reinforcement bar 71 are provided. As a reinforcement bar, a reinforcement bar 84 connecting the first split beam 11 and the second split beam 12 is provided.

[0020] When constructing the beam 1, as shown in FIG. 5, the first precast beam member 21 and the second precast beam member 22 are arranged in a state where the inner ends of the first beam width portion 21a and the second beam width portion 22a are in contact with each other, thereby forming a precast beam member 2 having a concave cross-sectional shape. The first upper main reinforcement 61 is arranged above the first precast beam member 21, and the protruding portion of the first stirrup 63 upward is hooked on the first upper main reinforcement 61 for reinforcement. The second upper main reinforcement 71 is arranged above the second precast beam member 22, and the protruding portion of the second stirrup 73 upward is hooked on the second upper main reinforcement 71 for reinforcement. After arranging the core bars 83 and the reinforcement bars 84, the concrete 3 is placed.

[0021] When placing the concrete 3, as shown in FIG. 5, the slab bars 51 of the slab 5 are arranged and the concrete 3 is placed, so that the slab 5 can be constructed together with the beam 1. For the column 4, as shown in FIG. 3, the column main reinforcement 41 is arranged and the concrete 3 is placed, so that the column 4 can be constructed.

[0022] The precast beam member 2 constituting the beam 1 is divided into a plurality in the beam length direction Y due to the relationship such as the weight of the precast beam member 2. As shown in FIG. 5, since the precast beam member 2 is divided into a first divided beam 11 and a second divided beam 12 in the beam width direction X, the number of divisions of the precast beam member 2 in the beam length direction Y can be reduced within the weight limit range, and the joint portions for joining the precast beam members 2 can be reduced.

[0023] As shown in FIG. 1, the length of the precast beam member 2 in the beam length direction Y is set to a length corresponding to the column span A (the same or substantially the same length as the column span A). Thereby, in the beam length direction Y, the joint portion between the precast beam members 2 can be made to coincide with the column corresponding portion 42 corresponding to the column 4 (the end portion of the column span A), so that the joint portion between the precast beam members 2 becomes a compression region against the long-term load.

[0024] Therefore, as shown in Fig. 4, at the joint between the first precast beam members 21 (precast beam members 2), as the joint form of the first lower main reinforcement bars 62, a clearance lapping joint is adopted in which the first joint bars 81 are placed on the upper part of the first precast beam members 21 (precast beam members 2) so that the first lower main reinforcement bars 62 and the first joint bars 81 do not come into contact with each other. As shown in Fig. 3, the first joint bars 81 are only placed on the upper part of the first beam width portion 21a of the first precast beam member 21, and the first joint bars 81 can be arranged at desired positions, thus simplifying the joint work.

[0025] The joint between the first precast beam members 21 (precast beam members 2) has been described with reference to Fig. 4. However, in Fig. 4, as indicated by the symbols in parentheses, for the joint between the second precast beam members 22 (precast beam members 2) as well, a clearance lapping joint is similarly adopted in which the second lower main reinforcement bars 72 and the first joint bars 81 do not come into contact with each other.

[0026] Regarding the first split beam 11 and the second split beam 12, at the column corresponding portion 42 corresponding to the column 4 in the beam length direction Y, as shown in Fig. 3, they are formed to be narrow in the beam width direction X and arranged on the outer side of the column 4. On the other hand, at the intermediate portion between the columns 4 in the beam length direction Y, as shown in Fig. 5, they are formed to be wide in the beam width direction X.

[0027] Therefore, regarding the stirrup lapping bars 63 and 73, as shown in Fig. 3, at the column corresponding portion 42, narrow stirrup lapping bars 63b and 73b that are formed to be narrow in the beam width direction X and arranged on the outer side of the column 4 are provided. On the other hand, as shown in Fig. 5, at the intermediate portion, wide stirrup lapping bars 63a and 73a that are formed to be wide in the beam width direction X are provided.

[0028] Also, regarding the upper main reinforcement bars 61 and 71 and the lower main reinforcement bars 62 and 72, the number of reinforcement bars and the like are different between the column-corresponding locations 42 and the intermediate portions in the beam length direction Y. Regarding the upper main reinforcement bars 61 and 71, as shown in FIG. 3, at the column-corresponding locations 42, there are two upper and lower stages of the upper main reinforcement bars 61a and 71a on the upper side and the upper main reinforcement bars 61b and 71b on the lower side. On the other hand, as shown in FIG. 5, in the intermediate portion, the number of the upper main reinforcement bars 61 and 71 is reduced compared to the column-corresponding locations 42 shown in FIG. 3, and the upper main reinforcement bars 61 and 71 with a small diameter are mixed. Regarding the lower main reinforcement bars 62 and 72, as shown in FIG. 3, at the column-corresponding locations 42, the number of the lower main reinforcement bars 62 and 72 is reduced compared to the intermediate portion shown in FIG. 5.

[0029] As shown in FIG. 2, in the beam length direction Y around the column 4, a second joint reinforcement bar 82 (shown by a dotted line in FIG. 2) that connects the first split beam 11 and the second split beam 12 is provided. As the second joint reinforcement bar 82, at the location where the column 4 does not exist, a short second joint reinforcement bar 82a with a short length is provided, and at the location where the column 4 exists, a long second joint reinforcement bar 82b with a long length and arranged in a state of penetrating the column 4 is provided.

[0030] 〔Alternative Embodiment〕 (1) In the above embodiment, regarding the upper main reinforcement bars 61 and 71 and the lower main reinforcement bars 62 and 72, the number of reinforcement bars and the like are made different between the column-corresponding locations 42 and the intermediate portions in the beam length direction Y, but the number of reinforcement bars and the like can also be configured in the same way.

Explanation of Reference Numerals

[0031] 1 Beam 2 Precast Beam Member 3 Concrete 4 Column 11 First Split Beam 12 Second Split Beam 42 Column-Corresponding Location 61 First Upper Main Reinforcement Bar 62 First Lower Main Reinforcement Bar 63 First Stirrup 71 Second Upper Main Reinforcement Bar 72 Second Lower Main Reinforcement Bar 73 Second starter muscle 81 First joint muscle A-pillar span B1 Beam width B2 Column width X Beam width direction Y Beam length direction

Claims

1. In a beam construction method of placing concrete on a precast beam member having a concave cross-sectional shape to construct a beam, the beam is a flat beam having a beam width larger than a column width, the precast beam member is divided in the beam width direction, the length of the precast beam member in the beam length direction is set to a length corresponding to a column span, In the joint portion between the precast beam members, as a joint form of the lower end main reinforcement, a joint bar is placed on the upper portion of the precast beam member, and a free overlapping joint in which the lower end main reinforcement and the joint bar do not contact each other is adopted. A beam construction method.

2. The beam is divided into two split beams in the beam width direction, each of the two split beams has a lower end main reinforcement and an upper end main reinforcement extending in the beam length direction, and a stirrup bar disposed in a state of winding the lower end main reinforcement and the upper end main reinforcement in a direction orthogonal to the beam length direction, The beam construction method according to claim 1, wherein at a column corresponding portion corresponding to a column in the beam length direction, the stirrup bars in each of the two split beams are formed to be narrow in the beam width direction and disposed outside the column.

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