JP2008180008A - Connection structure between column and beam, and method of constructing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection structure between a column and a beam, which can prevent cracking of concrete on a basement even if high-strength concrete is used, and is good in cost efficiency, and to provide a method of constructing the connection structure. <P>SOLUTION: In the connection structure 1 between the column and the beam, a cross sectional area of a column-beam connection portion 2 on a lower side of a first-floor column of a steel reinforced concrete structure is made larger than the cross sectional area of the first-floor column 3 and the cross sectional area of a basement column 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a column-beam joint structure and a construction method thereof.

Columns on lower floors in reinforced concrete super high-rise buildings must be constructed of high-strength concrete because of high axial force. Therefore, the strength of the high-strength concrete of the underground floor pillar is greater than that of the first floor pillar. For example, in the case of a 30-story super high-rise building, the concrete strength (Fc) of the first floor column needs to be 60 N / mm ^2. The Fc 60 N / mm ² with the same concrete strength is required. In addition, for example, in a super high-rise building having 40 stories or more, the concrete strength of the first floor column exceeds Fc 100 N / mm ² , so that Fc 100 N / mm ² is also required for the underground floor column. Therefore, when the strength of the high-strength concrete in the basement column is made smaller than that of the first-story column, the difference in the concrete strength is around Fc6N / mm ² unless special consideration is made. As shown in FIGS. 7 and 8, such a column-to-beam joint structure is such that the cross-sectional area of the underground floor column 20 is slightly larger than that of the first-floor column 21, and the column main reinforcement 22 of the first-floor column is used as the column beam. It was bent at the joint 23 and continuously arranged to the basement column 20. In addition, as another column-beam joint structure, for example, the invention of JP-A-2005-171728 is known.
JP 2005-171728 A

However, if high-strength concrete with almost the same strength as the first floor is used for the basement floor as in the above-mentioned joint structure between the pillar and the beam, the basement floor including the bearing wall has a large member cross section, There was a problem that heat generation increased and cracks due to an excessive temperature difference, that is, internal expansion and external initial drying shrinkage were likely to occur in the concrete. The high-strength concrete is very expensive, for example Fc30N / mm ² of 13000 yen / ^{m 3} becomes a high-strength concrete, Fc42N / mm In ² 19000 yen ^/ m 3, Fc60N ^/ mm In ² 21000 yen ^/ m 3, Fc80N / mm in ² 36000 yen ^/ m 3, the Fc100N / in mm ² 46000 yen ^/ m 3, Fc130N ^/ mm In ² 61000 yen / ^{m 3.} Therefore, high-strength concrete Fc130N / mm ^2, since approximately three times the price of high-strength concrete Fc60N / mm ^2, as a whole member cross section large basement, beam-column joints of 1 Kaibashira lower, There is a problem that it is not economical to use high-strength concrete having the same strength as the first floor for beams and floors.

  The present invention has been made in view of these problems, and its purpose is to prevent the cracking of concrete in the underground floor even when high-strength concrete is used, and to provide an economical column-beam joint structure and its construction method. Is to provide.

In order to solve the above problems, the column-beam joint structure is such that the cross-sectional area of the column-beam joint at the lower side of the first-floor column of the reinforced concrete structure is larger than the cross-sectional area of the first-floor column and that of the underground floor column. It is characterized by that. Moreover, it includes that the planar shape of the beam-column joint portion on the lower side of the first floor column is one of an octagon, a quadrangle, and a circle. In addition, it includes that the reinforcing bars are arranged on the outer peripheral side of the column beam joint on the lower side of the first floor column. In addition, the underground column is a double reinforcement of the column reinforcement of the first floor that is arranged to the bottom of the underground column and the other column reinforcement of the underground column that is arranged outside the column reinforcement. In addition, it is included that a fixing tool is installed at the upper end portion of the column main bar of the other column reinforcing bar. In addition, the concrete strength of the first floor column, the concrete strength of the underground floor column, and the concrete strength of the column beam joint portion on the lower side of the first floor column are included.
In addition, the method of constructing the joint structure between the column and the beam is to continuously arrange the column reinforcement of the underground floor column and the column reinforcement of the first floor column in the reinforced concrete structure, and to the outside of the column reinforcement in the underground floor column, After placing other column reinforcements in the basement column and installing a fixing tool at the upper end of the column main bar, the basement column formwork is assembled and formed, and the beam-to-column connection type on the lower side of the first column The frame is assembled and formed larger than the cross-sectional area of the first-floor pillar and the cross-sectional area of the basement pillar, and concrete is placed in the formwork of the basement pillar and is fixed under the beam. Concrete having a strength different from that of the concrete is placed in the formwork of the beam-column joint.

By making the cross-sectional area of the beam-column joint below the first-floor column larger than the cross-sectional area of the first-floor column and the cross-section of the underground floor column, high compressive stress can be dispersed at the beam-column joint. The strength of the pillars and bearing walls in the basement can be made smaller than those in the first floor pillar. For example, in the conventional configuration, 1 case Kaibashira is ^{Fc60N / mm 2, Fc50N / mm} 2 to Column Joints, although underground Kaibashira could not be dropped only Fc50N / mm ^2, structure of the present invention When the first floor pillar is Fc 60 N / mm ² , the column beam joint can be dropped to Fc 42 N / mm ² and the underground floor pillar can be dropped to Fc 36 N / mm ² . In the conventional configuration, when the first floor column is Fc 130 N / mm ² , only the column beam joint Fc 120 N / mm ² and the basement column column Fc 120 N / mm ² can be dropped. When the first floor pillar is Fc 120 N / mm ² , the column beam joint can be dropped to Fc 100 N / mm ² and the underground floor pillar can be dropped to Fc 60 N / mm ² . Therefore, in the present invention, the strength of the column beam joint and the underground story column can be reduced to about 50 to 80% of the strength of the first story column. As a result, the amount of expensive high-strength concrete used in the entire underground floor can be reduced, so that it becomes an effective measure for mass control, preventing concrete from cracking and improving the economic efficiency. In addition, the strength of the concrete of the basement column, 1st column, 1st column below and the beam / floor concrete can be divided, so that reasonable concrete strength setting, that is, each part is appropriate It can be concrete strength.

  Hereinafter, an embodiment of a method for constructing a column-to-beam joint structure and a column-to-beam joint structure according to the present invention will be described. In the embodiments of the joint structure and the construction method, the same components are described with the same reference numerals, and only different components are described with different reference numerals.

  This column-to-beam joint structure 1 is a first-column pillar-to-beam joint structure in a reinforced concrete super high-rise building. The concrete strength of the underground floor pillar 4 is to be made significantly smaller than that of the first floor pillar 3 by dispersing the high compressive stress by making it larger than the cross-sectional area of the underground floor pillar 4. This is to reduce the concrete strength of the members of the basement floor including the bearing wall, and to improve the effective mass control measures and economic efficiency.

  Thus, in order to make the concrete strength of the basement column 4 smaller than that of the first-story column 3, the cross-sectional area of the column beam joint 2 on the lower side of the first-story column is determined from the cross-sectional area of the first-story column 3 and the basement column 4 In addition, the cross-sectional area of the basement column 4 is made slightly larger than the cross-sectional area of the first-story column 3.

  As shown in FIG. 1, the column beam joint portion 2 is formed in a plane octagon larger than the cross-sectional areas of the first floor column 3 and the underground floor column 4. Each beam 5 is joined to the four opposite sides of the column beam joint 2, and the other four sides 6 connecting these beams pass through the four corners 7 of the basement column.

  In addition, as shown in FIG. 2, the first-column column reinforcement 10 composed of the column main reinforcement 8 and the strip reinforcement 9 is arranged at the column beam joint 2, and the constraining reinforcement 11 is provided at the corner of the column reinforcement 10. Are arranged along the four sides 6 connecting the beams. This is to prevent the concrete in the portion 12 having a large cross-sectional area from being cracked by resisting the distributed compressive stress with the restraint bars 11. Therefore, the first-floor column 3 and the underground floor column 4 having different cross-sectional areas were joined via the beam-to-column joint 2 on the lower side of the first-floor column, where the cross-sectional area was increased (the area of bearing pressure was increased). It is configured.

  The cross-sectional area of the beam-column joint 2 is the most efficient by calculating from the formula of the cross-sectional area of the beam-column joint below the first-floor column ≧ √ (Fc1 / FC2) × (first-floor column cross-sectional area) Can be set to any size. Here, Fc1 is the concrete strength of the first-floor column, and FC2 is the concrete strength of the beam-column joint. Will be.

Therefore, for example, when the first floor column 3 is set to Fc 130 N / mm ² and the underground floor column 4 is set to Fc 60 N / mm ² , the cross-sectional area of the column beam joint 2 is calculated from the above formula, and this concrete strength is calculated. Can also be set.

  The column beam joint 2 is not limited to the above-mentioned plane octagon, but may be a plane quadrangle or a plane circle.

  Further, as shown in FIG. 3, the underground floor pillar 4 has a slightly smaller cross-sectional area because the concrete strength is significantly smaller than that of the first floor pillar 3. And the column reinforcement 10 of the 1st floor column 3 is continuously arranged to the lower part of this underground floor column 4, and the other column reinforcement 13 of the underground floor column is arranged outside this column reinforcement 10. It is double reinforcement. A fixing tool 16 is installed at the upper end portion of the column main reinforcing bar 15 in the column reinforcing bar 13.

  When the size (cross-sectional area) of the first floor pillar 3 and the underground floor pillar 4 is different as described above, conventionally, as shown in FIG. Although it is bent and arranged in the underground floor column 20, if it is bent too much, it will be repelled by high stress, so such double reinforcement is used to resist high stress.

  Thus, the concrete of each part can be divided according to intensity | strength by setting the intensity | strength of the high-strength concrete of the column beam junction part 2 of the 1st floor, the underground floor pillar 4, and the beam 5 appropriately. As a method of laying, when the concrete strength of the beam-column joint 2 under the first floor column, the underground floor column 4 and the beam 5 are different from each other, first, the high-strength concrete of the underground floor column 4 is driven to the bottom of the beam. Thereafter, high-strength concrete having a strength different from that of the high-strength concrete is driven into the beam-to-column joint 2 below the first floor column, and finally, high-strength concrete having a strength different from that is driven into the beam 5.

  In addition, when the concrete strength of the column beam joint 2 below the first floor column and the underground floor column 4 is the same, first, the upper surface of the column beam joint 2 below the basement column 4 and the first column below. After the high-strength concrete is driven in, a high-strength concrete having a strength different from that of the high-strength concrete is driven into the beam 5.

  Next, an embodiment of a method for constructing the above-described column-beam joint structure will be described with reference to FIG. First, the column reinforcement 10 of the underground floor column and the column reinforcement 10 of the first floor column are continuously arranged on the concrete foundation 14, and another column reinforcement 13 is disposed outside the column reinforcement 10 of the underground floor column. To arrange double bars. And the fixing tool 16 is installed in the upper end part of the column main reinforcement 15 in this column reinforcement.

  Next, a wall reinforcing bar (not shown) of the bearing wall is arranged between these underground floor columns, and a beam reinforcing bar (not shown) is arranged at the column beam joint 2 on the lower side of the first floor column. Next, a column mold and a wall frame (not shown) are enclosed so as to surround the column reinforcement 10 of the basement column and the wall reinforcement of the bearing wall, and a beam mold (not shown) is enclosed so as to surround the beam reinforcement. Each is assembled and formed.

  And if the concrete strength of the beam-column joint 2 under the first floor column, the underground floor column 4, and the beam 5 are different from each other, the high-strength concrete is first driven to the bottom of the column formwork and the wall formwork. Then, high-strength concrete having a different strength is driven into the beam-column joint 2 on the lower side of the first floor column. Finally, when high-strength concrete having different strength is driven into the beam form, a column-beam joint structure 1 is constructed in which high-strength concrete having different strength is placed at each location.

  If the concrete strength of the beam-column joint 2 below the first-floor column is the same as that of the underground-floor column 4, first, the high-strength concrete up to the upper surface of the column-beam joint 2 below the first-floor column 4 and the first-floor column Then, high strength concrete having a strength different from that of the high strength concrete is driven into the beam 5.

Table 1 below shows a structural experiment of an ultra high strength reinforced concrete column of Fc 130 N / mm ² . Here, the test specimen was a scale model of 1/3 to 1/4 assuming a first floor pillar. Further, ultra high strength concrete having a concrete compressive strength (σ _B ) of 130 N / mm ² , a USD 685 grade main reinforcement (D16), and a shear reinforcement of SBPD 1275 were used for the columns. In addition, the lower part of the column is assumed to have a column beam joint, an underground floor column, and a first floor beam. The UHRC 19 is a 45 ° direction force. In the table, * 1 is (toughness guaranteed shear strength Rp = 0.01) / (section split method bending strength), and * 2 is (toughness guaranteed shear strength Rp = 0) / (section split method bending strength). In FIG. 3, the value in [] is the test piece compressive strength (care curing).

Moreover, UHRC18, UHRC19, and UHRC20 are the ones in which the column-to-beam joint structures 17, 18, and 19 shown in FIGS. As a result, the octagonal UHRC18 and UHRC19 at the joint portion directly below the column of Fc130N / mm ² generated vertical cracks and oblique cracks even when the load was applied from 1/25 to 1/20 rad. However, no peeling of the cover concrete was observed.

  On the other hand, in the case of UHRC20, which is a normal joint having the same size as the basement column 4, cracks in the cover concrete at the joint corner become large at 1/50 rad., Almost at the state just before peeling off at 1/33 rad. became. From this, the above-mentioned effect of the present invention could be confirmed.

  In addition, in said embodiment, although demonstrated using high-strength concrete, this is not restricted to high-strength concrete, It can apply also to concrete of normal intensity | strength.

It is a conceptual diagram of the joining structure of a pillar and a beam, (1) is a top view, (2) is a side view. (1) is a cross-sectional view of the beam-column joint, (2) is a cross-sectional view of the first-floor column, and (3) is a cross-sectional view of the basement column. It is sectional drawing of the junction structure of a column and a beam. (1) is a sectional view of a joined structure of columns and beams in a structural experiment, and (2) and (3) are hysteresis curve diagrams of (1). (1) is a sectional view of a joined structure of columns and beams in a structural experiment, and (2) and (3) are hysteresis curve diagrams of (1). (1) is a sectional view of a joined structure of columns and beams in a structural experiment, and (2) and (3) are hysteresis curve diagrams of (1). It is a conceptual diagram of the connection structure of the conventional pillar and beam, (1) is a top view, (2) is a side view. It is sectional drawing of the conventional junction structure of a pillar and a beam.

Explanation of symbols

1, 17, 18, 19 Column-to-beam joint structure 2, 23 Column-to-beam joint 3, 21 First-floor column 4, 20 Basement column 5 Beam 6 Four sides 7 Four corners 8, 15, 22 Column main bar 9 Strip 10 Column Reinforcement 11 Restraint 12 Concrete 13 Other column reinforcement 14 Concrete foundation 16 Fixing tool

Claims (6)

  A column-to-beam connection structure characterized in that the cross-sectional area of the beam-column joint at the lower side of the first-floor column of the reinforced concrete structure is larger than the cross-sectional area of the first-floor column and the cross-sectional area of the underground floor column.   2. The column-beam junction structure according to claim 1, wherein the planar shape of the beam-column joint portion on the lower side of the first-floor column is an octagon, a quadrangle, or a circle.   3. The column-to-beam joint structure according to claim 1 or 2, wherein a constraining bar is arranged on the outer peripheral side of the column-beam joint on the lower side of the first floor column.   The underground floor pillar is a double reinforcement of a column reinforcement of the first floor pillar arranged to the lower part of the underground floor pillar and another pillar reinforcement of the underground floor pillar arranged outside the pillar reinforcement, The column-to-beam joint structure according to any one of claims 1 to 3, wherein a fixing tool is installed at an upper end portion of the column main reinforcing bar of the other column reinforcing bar.   The column according to any one of claims 1 to 4, wherein the concrete strength of the first-floor column, the concrete strength of the basement column, and the concrete strength of the column beam joint at the lower side of the first-floor column are different from each other. And beam joint structure.   In the reinforced concrete structure, the column reinforcement of the underground floor column and the column reinforcement of the first floor column are continuously arranged, and the other column reinforcement of the underground floor column is arranged outside the column reinforcement of the underground floor column. After installing the fixing tool at the upper end of the pillar main bar, assembling and forming the formwork of the underground floor pillar, the formwork of the column beam joint on the lower side of the first floor pillar, and the cross-sectional area of the first floor pillar and the basement floor After assembling and forming larger than the cross-sectional area of the column, placing concrete in the formwork of the basement column and stopping it under the beam, in the formwork of the column beam joint on the lower side of the first floor column, A method for constructing a joint structure between columns and beams, characterized in that concrete having a strength different from that of concrete is cast.

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