JP4649065B2 - Junction structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a joint structure (hereinafter referred to as “joint structure”) between a pre-tensioned prestressed concrete beam member made of precast and a reinforced concrete column member.
[0002]
[Prior art]
When constructing a reinforced concrete structure with a large span, a prestressed concrete structure that introduces a compressive force in advance in the beam axis direction (longitudinal direction) of the beam member in order to suppress the long-term deflection and cracking of the beam member In general, the “PC structure” is employed. In constructing this PC structure, there are a post-tension method and a pre-tension method.
[0003]
The post-tension method is a method of applying a compressive force to concrete by applying a tensile force to the PC steel after the concrete is hardened, and has been widely applied as a known technique.
On the other hand, the pre-tension method is a method in which concrete is cast after applying a tensile force to the PC steel material, and a compressive force is applied to the concrete by releasing the tensile force after hardening.
[0004]
FIG. 5 shows a structure in which a pre-tension beam 80 and a column 90 are joined. In this pre-tension method, since the compressive force is introduced through the adhesion between the PC steel material 85 and the concrete 84, in order to efficiently transmit the tensile force of the PC steel material 85 to the concrete 84, relatively A plurality of PC steel members 85 having a small diameter (about 12.7 mm and about 15.2 mm) are connected to main reinforcing bars 81 and 82 in the beam axis direction and reinforcing bars 83 arranged around the main reinforcing bars 81 and 82. Separately, the bars are arranged parallel to the upper position of the main reinforcing bar 82.
[0005]
[Problems to be solved by the invention]
However, in the above method, since the plurality of PC steel members 85 are arranged separately from the main reinforcing bars 81 and 82 and the reinforcing bars 83, the PC steel material 85, the main reinforcing bars 81 and 82, and the reinforcing bars 83 interfere with each other. As a result, there is a problem that the arrangement and construction of the bar arrangement become complicated.
[0006]
6 schematically shows the stress distribution of the lower end reinforcement 82 (lower main reinforcement) and the PC steel material 85 arranged in the beam 80 over the entire length of the beam 80. As shown in FIG. That is, as shown in FIG. 6A, the stress distribution of the lower end stripe 82 is large at the beam end portion and is small in the vicinity of the beam center portion. On the other hand, as shown in FIG. 6B, the stress distribution of the PC steel material 85 is large in the vicinity of the beam central portion and is small at the beam end portion.
Thus, the stress of the lower end reinforcement 82 in the vicinity of the beam central portion and the stress of the PC steel material 85 at the beam end portion leave a surplus with respect to the yield stress, and the performance of each steel material can be effectively utilized. In addition, there is a problem that efficient design cannot always be performed.
[0007]
The present invention has been made in order to solve the above-described problems, and can be constructed at a shorter construction period and at a lower price, and has a high quality and can be designed efficiently. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the joint structure of the present invention, a prestressed concrete beam member of the pre-tensioning is made precast, at the junction structure between the reinforced concrete column member, the lower end of the prestressed concrete beam member has a plurality Main rebars are arranged side by side, and among the plurality of main rebars, the main rebars arranged at both outer edges of the prestressed concrete beam member are normal main rebars to which no tension is applied. The main reinforcing bars arranged inside the normal main reinforcing bars are tension main reinforcing bars in which a tension force is applied in the beam axis direction in advance, and are bent and fixed formed at end portions of the plurality of main reinforcing bars. The portion is fixed to the reinforced concrete column member.
Here, when it is simply made of precast, it includes both of full precast and half precast. Moreover, what is necessary is just to arrange | position the said main reinforcement appropriately according to the cross-sectional shape of a prestressed concrete beam member, use conditions, etc.
[0009]
According to the present invention, since the deformed reinforcing bar capable of increasing the adhesion strength to the concrete is used and the tension force is previously introduced into the main reinforcing bar, the main reinforcing bar also functions as a PC steel material in the conventional pretension system. Therefore, it is not necessary to provide PC steel separately. Therefore, since it is possible to prevent the PC steel material, the main reinforcing bar and the reinforcing bar from interfering with each other, which has been a problem in the past, it is possible to effectively suppress the long-term deflection and cracking of the concrete beam member.
Further, since the bent fixing portion of the main reinforcing bar is fixed to the reinforced concrete column member, it is possible to ensure bending load resistance performance during an earthquake or the like.
[0012]
Furthermore, the joint structure of the present invention is a joint structure of a pre-tensioned prestressed concrete beam member and a reinforced concrete column member, wherein the prestressed concrete beam member is in-situ with a prefabricated part made of half precast and made in advance. The pre-made part is arranged in the beam axis direction at the upper end part, the adjusting bar fixed to the concrete in a state where tension is applied in advance, and the beam axis direction at the lower end part to being Haisuji, possess a main reinforcement made of deformed bars which are fixed to the concrete, in a state given the pretensioned force, the adjusting muscle and the main reinforcing bar, after the concrete has cured, the By releasing the tension force, a compressive force is applied to the concrete .
[0013]
The present invention uses a prestressed concrete beam member composed of a ready-made part (a part using a so-called half-precast beam member) and a spot-fired part joined to the ready-made part. In this case, cracks may occur in the vertical direction on the upper surface of the ready-made part, but in the present invention, the adjusting bar is arranged near the upper surface of the ready-made part, and therefore the crack is generated. Can be prevented.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the building of the present invention will be described in detail with reference to the drawings.
In the description of each embodiment, the same constituent elements are denoted by the same reference numerals, and redundant descriptions are omitted.
[0015]
<First Embodiment>
As shown in FIG. 1, a joining structure 1 (first embodiment) of the present invention includes a pre-tensioned prestressed concrete beam member (hereinafter referred to as “PCaPC beam 10”), which is a full precast member, and a cast-in-place reinforced concrete column. This is a structure in which members (hereinafter referred to as “columns 30”) are joined at both ends of the PCaPC beam 10.
[0016]
The PCaPC beam 10 has a rectangular shape, and includes five upper main reinforcing bars (hereinafter referred to as “upper bar 11”) arranged in parallel to the upper end in the beam axis direction in a cross-sectional view, Five lower main reinforcing bars 12 (hereinafter referred to as “lower end bars”) which are parallel and are arranged at the lower end part in the beam axis direction in the cross-sectional view, and around the upper end bars 11 and the lower end bars 12 The concrete 14 is provided with reinforcing bars 13 that are arranged at predetermined intervals.
The upper bar 11 is a normal reinforcing bar, and the lower bar 12 is a high-strength deformed bar because a tensile force is introduced. However, the upper end bars 11 may be deformed bars.
[0017]
As described above, a tension force (tensile force) is applied to the lower end muscle 12, and then the concrete 14 is placed, and after the hardening, the tension force is released to compress the hardened concrete 14. There is a case where the main reinforcing bar to which tension is applied is referred to as “tensioned main reinforcing bar”, and the main reinforcing bar to which tension is not applied is referred to as “normal main reinforcing bar”. In each drawing, tension main reinforcement is indicated by ●, and normal reinforcement is indicated by ○)).
Further, the end portions 12 of the upper end bars 11 and the lower end bars protrude from the end face portions of the PCaPC beam 10, and are bent 90 degrees downward or upward to form bent fixing portions 11a and 12a. ing.
[0018]
The column 30 is a normal on-site reinforced concrete column, and a plurality of main reinforcing bars 31 arranged in a predetermined position in a column axial direction and a plurality of strip reinforcing bars 33 surrounding the main reinforcing bar 31 are made into concrete 34. Prepared inside.
The fixing end portion of the PCaPC beam 10 is disposed so as to be joined at the upper portion of the column 30 (hereinafter, this portion is referred to as “joining portion J”).
[0019]
In the embodiment described above, the case where all the lower end bars 12 are tension bars has been described.
However, the tension reinforcing bars may be appropriately arranged according to the cross-sectional shape of the PCaPC beam 10, the use conditions, and the like.
For example, the case shown in FIG. 2A shows a structure in which the tension main reinforcing bars in the PCaPC beam 10A are arranged in two steps below, and is used when a larger compressive force is applied to the concrete 14. It is. That is, in this case, in the cross-sectional view, similarly to the above-described embodiment, five tension main reinforcing bars are provided at the lowermost stage, and the vicinity of the upper part of the tension main reinforcing bars at both outer edges of the lowermost tension main reinforcing bars. It has a structure in which two tension main reinforcing bars are arranged.
[0020]
Further, in the case shown in FIG. 2 (b), a structure in which the tension main reinforcing bars in the PCaPC beam 10B are arranged in two steps downward and upward is shown, and due to the eccentric loading, the upper end of the PCaPC beam 10B is excessively large. This is used when a large tensile stress acts. That is, in this case, in a cross-sectional view, five main tension bars and five normal main reinforcing bars are provided at the lower end, and the main main reinforcing bars at both outer edges of the upper main ends are provided. It has a structure in which two tension main reinforcing bars are arranged in the lower part of the vicinity.
[0021]
Furthermore, in the case shown in FIG. 2 (c), a structure in which tensioned main reinforcing bars and normal main reinforcing bars are mixed and shown is shown. In the case where cracks can be suppressed with a relatively small tension force, It is used when a certain amount of cracking is allowed in the long term. That is, in this case, in a cross-sectional view, three main tension bars are provided inside the lowermost stage, and the main main reinforcement bars are arranged at both outer edges of the lowermost tension main reinforcement.
[0022]
[Construction construction method]
The construction method for the joint structure includes (1) a PCaPC beam manufacturing process and (2) a joint construction process.
[0023]
(1) Manufacturing process of PCaPC beam This process is a process of manufacturing the PCaPC beam 10 in advance in a factory or the like.
First, predetermined bar arrangement is performed, and a formwork (not shown) is installed around the bar, and then tension is applied by applying a tensile force to the lower end bar 12, and concrete 14 is placed.
Subsequently, after the concrete 14 is hardened, the lower end reinforcement 12 is fixed to the concrete 14 while gradually releasing the tension applied to the lower end reinforcement 12, thereby applying a compressive force to the hardened concrete 14.
[0024]
In addition, although it is necessary to form the bending fixing | fixed part 12a in the edge part of the lower end muscle 12 which provided tension | tensile_strength, it can carry out by various methods. For example, a method of placing concrete 14 after bending is applied to the lower end reinforcement 12 and a tensile force is applied to the lower end reinforcement 12 using a tension jig (not shown). Alternatively, it is possible to use a method of bending after fixing the lower end reinforcement 12 to which tension is applied to the concrete 14.
[0025]
(2) Joining part construction process This process is a process of joining the PCaPC beam 10 to the column 30.
First, on-site pillars 30 are constructed by performing predetermined bar arrangement and placing concrete 34 after placing a formwork (not shown) around it.
Subsequently, the bent fixing portions 11a and 12a of the PCaPC beam 10 are placed on the upper portion of the pillar 30, and after placing a formwork (not shown) around the periphery, concrete is placed to form the joint portion J. Built.
[0026]
[Action]
According to the joint structure K of the present invention, since the high strength deformed reinforcing bar capable of increasing the adhesion strength to the concrete 14 is used and the tension force is previously introduced into the lower end reinforcement 12, the lower end reinforcement 12 is conventionally provided. It also functions as a PC steel in the pre-tension system. Therefore, it is possible to prevent the PC steel material and the main reinforcing bar and the reinforcing bar, which were conventional problems, from interfering with each other, and it is possible to effectively suppress the long-term deflection and cracking of the PCaPC beam 10, In addition, it is possible to easily design and construct a joint structure that can ensure bending load resistance performance during an earthquake or the like.
[0027]
Further, since the bent fixing portion 12a of the lower end reinforcement 12 is fixed to the joint portion J with the column 30, it can be built in the same manner as a normal precast concrete beam member, and thus the workability is good and The fit of the part J can be improved.
In addition, when the method of providing a fixing plate at the end portion of the joint portion and fixing the linear lower end line without forming the bent fixing portion at the lower end line, the lower end line is provided in parallel. In many cases, a predetermined fixing length cannot be ensured due to interference between the lower end stripes, and it is difficult to fix in the joint portion. However, the present invention is very excellent in that the point is overcome.
[0028]
Here, when the stress distribution of the lower end reinforcement 12 in the joint structure 1 of the present invention is schematically shown over the entire length of the PCaPC beam 10, it is as shown in FIG. FIG. 3 (a) is a diagram showing the distribution of stress (hereinafter referred to as "PC steel corresponding stress") in which the lower end reinforcement 12 plays a role as a prestressing steel material. Larger and smaller at the beam end. FIG. 3B is a diagram showing an extracted distribution of stress (hereinafter referred to as “main bar corresponding stress”) in which the lower end bars 12 purely serve as main reinforcing bars. It is larger at the center and smaller at the center of the beam. FIG. 3C is a diagram showing the distribution of stress obtained by accumulating the PC corresponding stress and the main muscle corresponding stress. In practice, this value is generated in the lower end muscle 12.
According to this result, unlike the conventional case (see FIG. 6), the stress of the lower end bars 12 does not vary greatly over the entire length of the PCaPC beam 10, and a more economical design can be performed.
[0029]
<Second Embodiment>
As shown in FIG. 4, the joint structure 2 (second embodiment) of the present invention includes a prestressed concrete beam member (hereinafter referred to as “HPCaPC beam 20”) using a half precast member, and a column 30 similar to the above. Are joined at both ends of the HPCaPC beam 20.
[0030]
The HPCaPC beam 20 has a rectangular shape and is integrated with a ready-made part 20a (a part using a so-called half-precast member) manufactured in advance in a factory or the like and a concrete 25 placed on the upper part of the ready-made part 20a. It is formed from the on-site hitting part 20b.
[0031]
The ready-made part 20a has a rectangular shape, and in its cross section, five lower end bars 22 arranged in parallel to the lower end part in the beam axis direction in a cross sectional view, and both outer edge parts of the lower end bars 22 The two lower stresses 22 are arranged on the upper end of the two lower stress bars 22 and two prestress adjusting muscles 26 are arranged on the upper edge thereof. The lower end bars 22 and the prestressed adjusting bars 26 are high-strength deformed reinforcing bars and are given tension, and bent fixing portions 22a and 26a are formed at the ends thereof, and the joints J of the columns 30 are formed. (Reference numeral 21a indicates a bent fixing portion of the upper end stripe 21).
[0032]
In addition, the lower bar 22 and the prestressed adjusting bar 26 are surrounded, and an upper bar 23 protruding upward is arranged so as to correspond to the final cross-sectional shape of the PCaPC beam. Further, five upper bars 21 are pre-arranged in the beam axis direction on the lower surface of the horizontal portion above the barb 23 (reference numeral 24 indicates concrete).
[0033]
The pre-stress adjusting muscle 26 is arranged at the upper part of the ready-made part 20a, and due to the presence of the lower end muscle 22 to which tension is applied, a tensile stress is generated on the upper surface of the ready-made part 20a. In order to prevent the occurrence of cracks in the vertical direction, the bars are arranged near the upper surface of the existing portion 20a.
The on-site hitting portion 20b is constructed by placing concrete 25 around the protruding barbs 23 and upper end bars 21 of the ready-made part 20a.
[0034]
As described above, the joint structure 20 (second embodiment) of the present invention has the same effect as the joint structure 10 of the first embodiment, and the prestress adjusting muscle 26 is arranged near the upper surface of the ready-made part 20a. Therefore, cracks can be prevented from occurring on the upper surface of the ready-made part 20a.
[0035]
Heretofore, an example of a preferred embodiment has been described for the present invention. However, the present invention is not limited to the above-described embodiment, and it goes without saying that the design of each of the above-described constituent elements can be appropriately changed without departing from the spirit of the present invention.
In particular, the number and type of main reinforcing bars to which tension is applied can be determined appropriately.
[0036]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while being able to construct with a short construction period and a low price, it is possible to provide a joining structure that enables high-quality and efficient design.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams showing a bonding structure (first embodiment) according to the present invention, in which FIG. 1A is a longitudinal sectional view, and FIG. 1B is a sectional view taken along line XX in FIG.
FIGS. 2A to 2C are cross-sectional views showing other examples of the PCaPC beam of the present invention.
FIG. 3 is a view showing the stress distribution of the lower end bars of the PCaPC beam over the entire length in the joint structure of the present invention. FIG. 3A is a stress distribution in which the lower end bars play a role only as a prestressing steel material [A (B) is a diagram showing the distribution of stress [B] in which the lower bar only serves as the main reinforcing bar, and (c) is a diagram showing the stress distribution of [A + B]. Show.
4A and 4B are views showing a bonding structure (second embodiment) according to the present invention, in which FIG. 4A is a longitudinal sectional view, and FIG. 4B is a YY sectional view in FIG.
5A and 5B are diagrams showing a conventional joining structure, in which FIG. 5A is a longitudinal sectional view, and FIG. 5B is a ZZ sectional view in FIG.
6A and 6B are diagrams showing the stress distribution of the lower end bars of the beam in the conventional joint structure over the entire length thereof. FIG. 6A shows the stress distribution of the main reinforcing bars and FIG.
[Explanation of symbols]
1, 2 Joint structure J, J 'Joint 10 PCaPC beam (prestressed concrete beam member)
11, 21 Top bar (upper main bar)
12,22 Bottom bar (lower main bar)
11a, 12a Bent fixing part 20 HPCaPC beam (prestressed concrete beam member)
20a Ready-made part 20b Field hitting part 20c Joint surface 26 Prestress adjusting bars 22a and 26a Bending fixing part 30 Column (on-site cast-in-place reinforced concrete pillar member)

Claims (2)

In the joint structure between pre-stressed prestressed concrete beam members made of precast and reinforced concrete column members,
A plurality of main reinforcing bars are juxtaposed at the lower end of the prestressed concrete beam member ,
Among the plurality of main reinforcing bars, the main reinforcing bars arranged at both outer edges of the prestressed concrete beam member are normal main reinforcing bars to which no tension is applied, and are arranged inside the normal main reinforcing bars. The main rebar is a tension main rebar in which tension is applied in the beam axis direction in advance,
A joining structure, wherein a bent fixing portion formed at an end portion of the plurality of main reinforcing bars is fixed to the reinforced concrete column member. In the joint structure of prestressed prestressed concrete beam members and reinforced concrete column members,
The prestressed concrete beam member is formed from a pre-fabricated part and a spot hitting part that are manufactured in advance,
The ready-made part is arranged in the beam axis direction of the upper end part, and the adjusting bar fixed to the concrete in a state in which tension is applied in advance .
Is Haisuji the beam axis direction of the lower end portion, possess a main reinforcement made of deformed bars which are fixed to the concrete, in a state given the pretensioned force,
The joint structure characterized in that the adjusting bar and the main reinforcing bar apply compressive force to the concrete by releasing the tension after the concrete is hardened .

Images