JP3579659B2 - Columnar structure and method of constructing the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a columnar structure and a method for constructing the same.
[0002]
[Prior art]
Conventionally, a reinforcing bar has been used as a main bar of a precast member. Reinforcing bars are limited to a maximum length of 12 m due to transportation reasons. To use them as long reinforcing bars, measures such as connection using mechanical joints at the site or connection by pressure welding are required. It is. Therefore, a long reinforcing bar requires labor such as man-hours and time for connection. In addition, in order to insert a long reinforcing bar into a columnar concrete structure, a heavy machine such as a crane having a long stroke capable of lifting a long material and a work space for the crane are required.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a technique that overcomes the difficulty caused by using the above-described reinforcing bar as a main bar of a columnar structure.
[0004]
[Means for Solving the Problems]
The present invention is made by stacking the precast blocks on the footing, using a line from P C steel with a longitudinal main reinforcement, twisted the PC steel crimp grip for fixing to concrete, in the footing and A pillar-shaped structure characterized by being a main reinforcing bar attached to an intermediate portion of a PC stranded wire so as to be positioned at least one in each precast block. By using a high-strength PC steel stranded wire that can be continuously conveyed by a coil as a reinforcing bar, a connecting joint of the reinforcing bar becomes unnecessary. There is no need for a long body truck for transportation, and a normal truck is sufficient. It is possible to insert the reinforcing bar into the columnar structure without using any heavy equipment and with a simple device or human power. There are advantages such as the space required for insertion can be made in a small space. However, PC steel strands have a different adhesion mechanism to concrete than rebar, and because of adhesion not by bearing pressure but by friction, the adhesion strength is low, and the problem that the adhesion is cut off immediately when a tensile load is applied. There is. Therefore, it is necessary to install and fix the fixing parts at both ends of the PC steel strand. In addition, since it is in an unbonded state in concrete, the deformation tends to increase.
[0005]
According to the present invention, in order to improve the adhesion of the PC steel strand, a crimping grip is crimped at a certain interval in the middle of the PC steel strand, and the crimping grip is fixed to the concrete by supporting pressure of the shoulder of the crimping grip. A similar attachment function was performed.
[0006]
In such a columnar structure, if an unbonded section is provided between the crimping grip in the footing and the crimping grip in the lowermost precast block, the elongation of this part absorbs displacement due to seismic load etc., and the structure is rich in toughness It becomes. For this purpose, it is preferable to provide a crimping grip so that the unbonded section is as long as possible .
[0007]
When a PC steel stranded wire is used as a substitute for a reinforcing bar as a main reinforcing bar, the bonding strength between the PC steel stranded wire and concrete or mortar is small, and when the main reinforcing bar receives a tensile load, the bond breaks and the unbonded section is expanded. As a result, in the case of a bridge pier, pulling out of the stranded wire from the footing and reduction in strain cause a decrease in tensile resistance.
[0008]
For piers, a design method has been adopted in which cracks due to seismic loads or the like are guided to specific locations at the bases of the piers, and fracture locations are specified. Therefore, the length of the unbonded section is adjusted by installing a crimping grip across the crack induction location (joint near the base in the case of a columnar structure made of precast concrete) and adjusting the interval. As a result, the deformation performance of the pier can be improved. That is, when the interval between the crimp grips is increased and the length of the unbonded section is increased, the allowable value of the elongation of the main bar at that portion increases, and the deformation performance also improves.
[0009]
Construction of the above structure can be achieved as follows. In building the columnar structure by stacking the precast concrete blocks, the concrete blocks are stacked on the footing, temporarily bonded, and the footing and the sheath in the concrete block are filled with grout, and then the inside of the footing and inside each precast block. The main reinforcing steel is formed by inserting a PC steel stranded wire with the crimping grip crimped so as to be positioned in the sheath into the sheath. At this time, if the distance between the crimping grip in the footing and the crimping grip in the lowermost block is made as large as possible, the deformability of the columnar structure can be increased.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the present invention, a press grip is press-bonded to a PC steel stranded wire at a position having a predetermined interval to improve the adhesion performance with concrete or mortar. By using the PC steel strand as the main reinforcing bar, the connection of the main reinforcing bar by the joint can be omitted, continuity can be ensured, and it is economical and workability is improved. The applicable structure can be applied to a cast-in-place structure, and can be applied to a precast structure and the like. Further, there is an excellent characteristic that the length of the unbonded section can be adjusted by adjusting the interval between the crimp grips.
[0011]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a schematic longitudinal sectional view of the pillar structure 1 of Example, the left half of Figure 1 shows what unbonded section 11 is relatively short, the right half of FIG. 1 has a longer length of the unbonded section 11 Showing things. A precast concrete block 3 is stacked on the footing 2, a main reinforcing bar made of a PC steel stranded wire is arranged in a vertical sheath 4, and a crimping grip 6 is attached to an intermediate portion of the PC steel stranded wire 5. . The crimping grip 6 is attached so as to be present in the footing 2 and the block 3 respectively. The line 5 PC strand More crimping grip 6 are fixed to the concrete or mortar, and has a structure to prevent a decrease in pullout and tensile resistance from the footing 2. As a result, it can be expected that the PC steel stranded wire 5 acts as a main reinforcing bar in the same manner as the reinforcing bar up to its holding strength. The operation of crimping the crimp grip 6 to the PC steel strand 5 can be easily performed on site. If you leave long unbonded section 11 as shown in the right half of FIG. 1, the elongation of the A spunbonded ku between 1 1 Daito ing. PC steel strands have large elongation and do not yield, thus improving the restoring function. For seismic intensity level earthquakes, the PC steel strand has a sufficiently high yield strength, so even if a crack 12 occurs at the base of the columnar structure due to the earthquake, the PC steel strand 5 returns thereafter, The crack 12 is repaired.
[0012]
After the mortar (grout 7) is injected into the sheath 4, the PC steel strand 5 is pressed into the sheath 4 from above the columnar structure and inserted into the sheath 4 from above the columnar structure.
[0013]
A model similar to the columnar structure shown in FIG. 1 was prepared, a PC steel stranded wire having a crimping grip attached in a footing was inserted from above into a sheath filled with grout, and after curing, the PC steel wire was pulled upward. As a result of the test, a result was obtained in which the pull-out force was increased to the tensile strength of the PC steel strand without causing the pull-out of the strand from the PC steel, and the excellent performance of the present invention was confirmed.
[0014]
【The invention's effect】
According to the present invention, since a high-strength PC steel strand can be used as a vertical main reinforcing bar of a columnar structure in the same manner as a reinforcing bar,
(A) The strength of the precast structure itself is increased. (B) The rebar performance is improved because the PC steel strand has a large elongation and does not yield. (C) Even if a crack occurs at the seismic intensity level earthquake, After unloading, the PC steel wire returns and cracks are repaired. (D) Because of high strength, the number of main reinforcing bars is reduced as compared with steel bars, so that space can be spared and the cross section of the columnar structure can be reduced. (E) The performance of high-strength concrete can be effectively used, and the construction is simplified, so that excellent effects such as improvement in economic efficiency are exhibited.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a columnar structure of an embodiment. The left half shows an example in the case of having a normal unbond section, and the right half shows an example in which the unbond section is lengthened.
[Explanation of symbols]
1 columnar structure 2 footing 3 precast blocks 4 sheath 5 PC steel stranded wires 6 crimp grip 7 grout 8 joints 11 A spunbonded ku between 12 Cracking

Claims (3)

It was stacked precast blocks on the footing, using a line from P C steel with a longitudinal main reinforcement, twisted the PC steel crimp grip for fixing to concrete, in the footing and in each pre-cast blocks A columnar structure characterized by being a main reinforcing bar attached to an intermediate portion of a PC stranded wire so as to be positioned at least one at a time. 2. The columnar structure according to claim 1, wherein an unbonded section is provided between the crimping grip in the footing and the crimping grip in the lowermost precast block. In building the columnar structure by stacking the precast concrete blocks, the concrete blocks are stacked on the footing, temporarily bonded, and the footing and the sheath in the concrete block are filled with grout, and then inside the footing and each precast block. A method of constructing a columnar structure, comprising: inserting a PC steel stranded wire having a crimping grip crimped so as to be positioned inside the sheath to form a main reinforcing bar.

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