JP3817095B2 - Construction method of non-embedded column base of steel reinforced concrete structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention joins an anchor bolt embedded in a reinforced concrete foundation and a leg portion of a column steel frame, and arranges a column main reinforcement embedded in the foundation around the column steel frame to form a steel reinforced concrete column. Further, the present invention relates to a non-embedded column base of a steel reinforced concrete structure that transmits the stress of the steel reinforced concrete column to the foundation.
[0002]
[Prior art]
As shown in FIG. 4, the steel column reinforced concrete column base is a portion that transmits the force received by the column 4 to the foundation F. Since the foundation F is made of reinforced concrete, the column base is a portion that joins the column steel 6 and the reinforced concrete. That is, as shown in FIG. 5, anchor bolts 8 and column main reinforcing bars 9 are embedded in a reinforced concrete foundation F in advance, and a column steel frame 6 with a base plate 7 welded to the lower end portion is erected, and the base plate 7 is fixed to the anchor bolts 8. The column steel frame 6 and the reinforced concrete part are joined with a nut. The base plate 7 is placed on a base mortar that is formed one level higher on the top end of the base F. And after joining the column steel frame 6, the hoop reinforcement 10 is wound around the column main reinforcement 9, and concrete is laid, and the column lower part is wrapped. When two or more pillars are erected, a concrete connecting beam (underground beam) 5 in which concrete is placed by placing underground beam 11 and stirrup 12 between foundation F and foundation F. Is provided.
[0003]
The column base of such a steel reinforced concrete structure is roughly classified into a non-embedded type and an embedded type.
As shown in FIG. 5 (a), the non-embedded column base part does not embed the column steel 6a in the foundation F, but joins the column steel 6a to the anchor bolt 8 at the top end position of the underground beam 5; A large number of column main bars 9 and hoop bars 10 are arranged around the column steel frame 6a, and the lower part of the base plate 7 has a reinforced concrete structure.
[0004]
As shown in FIG. 5 (b), the embedded column base portion extends the column steel frame 6b into the underground beam 5 and joins it to the anchor bolt 8 inside the foundation F, and a large number of column main bars around the column steel frame 6a. 9 and the hoop bars 10 are arranged so that the column bases have a steel reinforced concrete structure.
[0005]
[Problems to be solved by the invention]
By the way, in the Hyogoken-Nanbu Earthquake, there were cases where the non-embedded column bases were destroyed. According to the survey of non-embedded column bases damaged by the Hyogoken-Nanbu Earthquake, the damage to the column bases is thought to be mainly due to repeated large tensile and compressive forces during the earthquake. That is, in the event of an earthquake, the reinforcing bars, etc. pull and yield, and the amount of plastic elongation increases rapidly, tensile cracks occur in the surrounding foundation (concrete), and the concrete is pulled out in a conical shape and destroyed (cone destruction). It is thought that the base mortar under the base plate was destroyed by this cone breakage, the stress transfer from the column steel frame 6 suspended on the base mortar via the base plate to the foundation F became impossible, and the column base was destroyed. .
[0006]
Therefore, after the Hyogoken-Nanbu Earthquake, when designing the column base, it is common to use the embedded column base, and the conventional non-embedded column base is not used.
[0007]
However, in the embedded column base, the column steel frame 6b is disposed up to the underground beam 5, so that the underground beam main bar 11 intersects the column steel frame 6b. For this reason, it is necessary to devise measures to prevent the underground beam main reinforcement 11 from colliding with the steel column, such as by attaching a horizontal haunch to the underground beam 5. Becomes complicated and the workability is poor.
[0008]
Further, in the embedded column base, the first-stage column steel frame 6b needs to be manufactured before the underground beam 5 is constructed, causing a very troublesome situation in setting up the construction process.
[0009]
Therefore, there was a long-awaited desire to improve the non-embedded column base with good workability and to have a structure that can withstand earthquakes of the magnitude of the Hyogoken-Nanbu Earthquake. As described above, the present invention has been made in view of the above-mentioned problems, and it is possible to reliably transmit stress from the column steel to the foundation, and the workability of the column base is easy. It aims at providing the construction method of a leg part.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the following means are adopted in the non-embedded column base of the steel reinforced concrete structure of the present invention.
[0011]
In other words, the construction method of the non-embedded type column base of steel reinforced concrete of the present invention is provided integrally with the leg portion of the anchor bolt and the bar steel embedded leaving the tip end portion to the crest of the foundation of reinforced concrete causes joined at top end of the base and a base plate which is, by Haisuji the embedded set by pillars main reinforcement to the foundation around the pillar steel forming a steel reinforced concrete column, the stress in the steel reinforced concrete columns In the construction method of the non-embedded column base of the steel reinforced concrete structure transmitted to the foundation,
When embedding the pillar main reinforcement to the foundation, and wherein it to contain a step of the concrete of the foundation and the pillar main reinforcement is prevented from adhering predetermined depth from the top end of the previous SL foundation.
[0012]
According to the present invention, the column main reinforcement is configured to include a step of preventing the column main reinforcement and the foundation (reinforced concrete) from adhering to each other by a predetermined depth from the top of the foundation where the cone breakage is likely to occur. Even if plastic elongation occurs due to yielding, etc., the column main reinforcement and the foundation (reinforced concrete) are not attached to each other at a predetermined depth from the top of the foundation, so that there is no tension cracking in the surrounding concrete. Therefore, it is possible to eliminate the cone destruction due to the pulling force of the concrete below the top of the foundation that triggers the column base part destruction. As a result, it is possible to prevent the column base part from being destroyed by the earthquake, and from the upper steel reinforced concrete column. Since the stress cannot be transmitted to the foundation, the structural performance of the non-embedded column base can be improved.
[0013]
Further, in the method of constructing the non-embedded type column base of steel reinforced concrete of the present invention, a predetermined depth in the range to avoid the deposition until Haisuji been stirrup surface from crest to said foundation of said foundation It is also possible to exemplify a configuration in which the distance is equal to or greater than the distance from the top of the foundation and is three times the diameter of the reinforcing bar of the column main bar. Furthermore, in the construction method of the non-embedded column base portion of the steel reinforced concrete structure of the present invention, the step of preventing the adhesion to the predetermined depth is a step of covering the column main bar with the adhesive cutting material by the predetermined depth. Some configurations can also be illustrated.
[0014]
According to this example, but it is to avoid attachment at a distance from the top end of foundation cone fracture occurs until foundation Haisuji the rebar (underground beams stirrups) range to not adhere If it is too large, the rigidity of the column base will be reduced. Therefore, the range in which it does not adhere is within a distance of about 3 times the diameter of the reinforcing bar of the column main bar from the top of the foundation. Incidentally, distance basis about 3 times the rebar diameter of the pillar main reinforcement is conical cone fracture having an angle of 30 ° to 40 ° in about three times the distance the depth of the reinforcing bar diameter pillar main reinforcement It is easy to occur, and it is based on the experimental result that cone destruction does not occur at the depth after that (refer to FIG. 2 and FIG. 3).
[0015]
In addition, as a method to prevent the column main reinforcement and the concrete of the foundation from adhering to the base top by a predetermined depth, there are a method of wrapping rubber tape etc. around the column main reinforcement and a method of covering the column main reinforcement with a vinyl tube etc. It can be illustrated as an easy work method.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a non-embedded column base portion of a steel reinforced concrete structure according to an embodiment of the present invention will be described with reference to FIGS.
[0017]
The steel column reinforced concrete non-embedded column base of the present invention is a part that transmits the force (stress) received by the steel reinforced concrete column 4 to the foundation F as shown in FIG.
The foundation F is formed of a foundation main body and a connecting beam (underground beam) 5 joined to the foundation main body from a horizontal two-character direction, and is reinforced concrete.
[0018]
The foundation main body is laid with a discarded concrete 21 on a granite stone 20, and a base concrete 22, a diagonal base 23, a laying reinforcement 24, a column main reinforcement 9, and a hoop reinforcement 10 are arranged on the discarded concrete 21, and the rear concrete. Reinforced concrete structure by placing
[0019]
The underground beam 5 has two underground beam main bars 11 penetrating the foundation main body from the horizontal two-letter direction, and two stirrups 12 for winding the underground beam main bars 11 are arranged to arrange the rear concrete. It is cast and reinforced concrete. In this embodiment, the upper ends of the foundation main body and the underground beam 5 are the top ends of the foundation F.
[0020]
As shown in FIG. 1, the foundation F has a rectangular base mortar 13 which is formed one step higher and flat on the upper part of the foundation body. On this base mortar 13, the base plate 7 provided integrally with the leg portion of the column steel frame 6 is placed.
[0021]
The column steel frame 6 is H-shaped steel, and a rectangular base plate 7 is welded to the lower end portion thereof.
The base plate 7 is a rectangular iron plate that is slightly smaller than the planar outer shape of the base mortar 13, and has four mounting holes.
[0022]
Further, four anchor bolts 8 are embedded in the base F in a state where the tip screw portion is seen on the base mortar 13. The arrangement of the four anchor bolts 8 corresponds to the four mounting holes of the base plate 7. The column steel frame 6 and the base plate 7 are fixed to the foundation F by screwing nuts into the threaded portions of the anchor bolts 8 inserted into the mounting holes.
[0023]
Further, eight column main bars 9 are embedded in the foundation F so as to have the tip portion look into the foundation main body and the underground beam 5 (the top end of the foundation F) and surround the base mortar 13 at equal intervals. This column main reinforcing bar 9 uses D25 (deformed bar having a diameter of 25 mm).
[0024]
As shown in FIGS. 1 and 4, the column main reinforcement 9 is arranged by winding a hoop reinforcement 10. The column 4 is formed by placing concrete on the column main reinforcement 9 and the hoop reinforcement 10 that have been arranged.
[0025]
The column main reinforcement 9 is embedded in the foundation F after the adhesive cutting material (rubber tape) 14 is wound so that the concrete of the foundation F does not adhere from the top end of the foundation F by a predetermined depth L. The range of the predetermined depth L to prevent adhesion is greater than the distance from the upper surface of the underground beam 5 (the top end of the foundation F) to the surface of the stirrup 12 arranged in the underground beam 5, and distance is preferably about three times the rebar diameter pillar main reinforcement from the beam 5 top (25mm) (75mm), in this embodiment, it is 75mm predetermined depth L.
[0026]
Next, the reason for preventing the column main reinforcement 9 and the concrete of the foundation F from adhering from the top end of the foundation F by a predetermined depth L when the column main reinforcement 9 is embedded in the foundation F will be described. 2 and 3 show a test piece in which a column main reinforcing bar 2 of D41 (a deformed reinforcing bar with a diameter of 41 mm) is buried in the center of a cubic concrete block 1 with a side of 900 mm, and is embedded to the root. 2 is a plan view, and FIG. 3 is a cross-sectional view taken along the line AA.
[0027]
2 and 3 show a state after the concrete block 1 and the column main reinforcement 2 are separately fixed, the column main reinforcement 2 is pulled and yielded, and the extension amount is rapidly increased. In addition, it is thought that such a large extension / compression force occurs alternately during an earthquake.
[0028]
According to the experiment, as shown in FIG. 2, the tensile crack 3 is generated in the concrete around the columnar reinforcement 2, and the concrete is pulled out in a conical shape to break the cone. Then, as shown in FIG. 3, the cone breakage occurs at an angle of 30 ° to 40 ° from a depth of about 2 to 3 times (about 80 mm) of the diameter (41 mm) of the column main reinforcement 2 fixed from the concrete surface. It was found to be destroyed in a conical shape.
[0029]
Therefore, by including a step of preventing the column main reinforcement 9 and the concrete of the foundation F from adhering by a predetermined depth L from the top edge of the foundation F where the cone breakage is likely to occur , the extension and compression forces are alternated. Even if repeated, the structure is such that the plastic elongation due to the yielding of the column main reinforcement 9 is not transmitted to the surrounding foundation (concrete) F, and the concrete is pulled below the top edge of the foundation F that triggers the destruction of the column base. Can prevent cracking due to force.
[0030]
However, if the range for preventing adhesion is too large, the rigidity of the column base portion may be reduced, and the deformation of the building during an earthquake may increase. Therefore, as shown in the experimental results, it is necessary to prevent the cracks from adhering from the upper surface of the underground beam 5 where the cracks occur in a conical shape by a distance of about 3 times (75 mm) the diameter of the reinforcing bar (25 mm) of the column main reinforcing bars 9.
[0031]
The above is the basis for preventing the column main reinforcement 9 and the concrete of the foundation F from adhering to the base F by a predetermined depth L when the column main reinforcement 9 is embedded in the foundation F. Next, the operation of this embodiment will be described.
[0032]
According to this embodiment, since the adhesion between the column main reinforcement 9 and the foundation F is removed in a specific range downward from the top end of the foundation F, the plastic elongation due to the yield of the column reinforcement generated in the event of an earthquake occurs. However, there is no tension cracking in the surrounding concrete. Therefore, it is possible to eliminate the cone destruction due to the pulling force of the concrete below the top of the foundation F that triggers the destruction of the column base. As a result, the column base can be prevented from being destroyed by the earthquake, and the upper steel reinforced concrete column can be prevented. Since the stress cannot be transmitted from 4, the structural performance of the non-embedded column base can be greatly improved. Therefore, according to this embodiment, it is possible to solve the problem of the underground beam main reinforcement and the column steel frame, which is a problem in the embedded column base, the horizontal hunch of the underground beam 5 is unnecessary, and the workability can be greatly improved.
[0033]
Moreover, according to this embodiment, since the column steel frame 6 is only above the underground beam 5, it is possible to afford to manufacture the steel frame only during the underground beam construction period. Furthermore, according to this embodiment, operations to avoid adhering the pillar main reinforcement 9, a range that does not adhere is small, since only covering the pillar main reinforcement in rubber tape, work is good easy workability.
[0034]
In this embodiment, the method of removing the adhesion of concrete from the column main reinforcement 9 has been described by the method of wrapping the rubber tape around the column main reinforcement 9. However, the column main reinforcement 9 is covered with a vinyl tube or the like so that the work is easy. You can go.
[0035]
Further, as a similar case, the present invention can also be applied to a case where a steel column base is rooted with reinforced concrete.
[0036]
【The invention's effect】
According to the present invention, the following effects can be obtained. According to the present invention, the column main reinforcement is configured to include a step of preventing the column main reinforcement and the foundation (reinforced concrete) from adhering to each other by a predetermined depth from the top of the foundation where the cone breakage is likely to occur. Even if plastic elongation occurs due to yielding, etc., the column main reinforcement and the foundation (reinforced concrete) do not adhere to each other at a predetermined depth from the top edge of the foundation, so that tensile cracks do not occur in the surrounding concrete. Therefore, it is possible to eliminate cone destruction due to the tensile force of the concrete below the top of the foundation that triggers column base destruction, and as a result, it is possible to prevent the column base from being destroyed by an earthquake, and from the upper steel reinforced concrete column Since the stress cannot be transmitted to the foundation, the structural performance of the non-embedded column base can be greatly improved. Therefore, according to the present invention, it is possible to solve the problem of the underground beam main bar and the column steel frame, which is a problem in the embedded column base, the need for a horizontal haunch for the underground beam, and the workability can be greatly improved.
[0037]
In addition, according to the present invention, since the column steel frame is only above the underground beam, it is possible to afford to manufacture the steel frame only during the underground beam construction period.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a non-embedded column base portion of a steel reinforced concrete structure according to an embodiment of the present invention.
FIG. 2 is a plan view showing a state of conical fracture (cone fracture) of concrete in an experiment of fixing reinforcing bars to concrete.
FIG. 3 is a cross-sectional view taken along line AA of FIG. 2 showing a state of concrete conical fracture (cone fracture) in an experiment of fixing reinforcing bars to concrete.
FIG. 4 is a perspective view of a column base part of a steel reinforced concrete structure.
5A and 5B are longitudinal sectional views of a conventional non-embedded column base, FIG. 5A shows a non-embedded column base, and FIG. 5B shows an embedded column base.
[Explanation of symbols]
1 ... Concrete block (test piece)
2 ... Column reinforcement 3 ... Crack 4 ... Column 5 ... Underground beam 6 ... Column steel frames 6a-6b ... Column steel frame 7 ... Base plate 8 ... Anchor bolt 9 ... Column main reinforcement 10 ... Hoop muscle 11 ... Underground beam main reinforcement 12 ... Stirrup 13 ... Base mortar 14 ... Adhesive cutting material

Claims (3)

Causes joined at top end of the base and a base plate which is provided integrally with the leg portion of the buried anchor bolt and the bar steel leaving the tip end portion to the crest of the foundation of reinforced concrete, embedded in the foundation In the construction method of the non-embedded column base of the steel reinforced concrete structure in which the column main reinforcement is arranged around the column steel to form a steel reinforced concrete column, and the stress of the steel reinforced concrete column is transmitted to the foundation.
When embedding the pillar main reinforcement to the foundation, the pillar main reinforcement and of the foundation concrete and is steel reinforced concrete, characterized in it to contain steps to avoid adhering by a predetermined depth from the top end of the previous SL foundation Non-embedded column base construction method . Predetermined depth range to avoid the adhesion, rebar diameter of the pillar main reinforcement from crest of the foundation be more than the distance to Haisuji been stirrup surface to the foundation, and the crest of the foundation The construction method of the non-embedded type column base part of the steel-framed reinforced concrete structure of Claim 1 set to the distance of 3 times . The non-embedded column base part of steel reinforced concrete structure according to claim 1 or 2, wherein the step of preventing the adhesion to the predetermined depth is a step of covering the column main reinforcing bar with an adhesive cutting material by the predetermined depth. Construction method .

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