JPS60181457A - Prestressed concrete pillar having pc strand mounted in x-shape therein under tension - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention effectively improves the strength and toughness of reinforced concrete columns in a simple manner.

Originally, it is a reinforced concrete construction (hereinafter abbreviated as 'RC construction')
Columns are generally stronger against compressive loads than steel-framed columns, but they are weaker against tensile, bending, and shear loads, and are hard and brittle, so once cracks occur, their yield strength decreases rapidly. There are drawbacks. On the other hand, steel-framed columns are strong against tension and bending, but are weak against compression buckling, and have the disadvantage of requiring a large amount of protection and anti-corrosion coating, which takes time and money.

Generally speaking, steel reinforced concrete columns are often used in high-rise buildings to take advantage of the advantages of both and compensate for their disadvantages, but this is more labor-intensive and considerably more expensive than RO columns. Another option is to build pillars made of Brestre rental construction (hereinafter abbreviated as 'po construction'), but this requires extensive equipment and setup, strict quality and construction management, and special technology that makes full use of them. Because of the high construction cost and time required, it is currently rarely used in general construction, except in special cases with particularly long spans and enormous stress.

To remove this barrier, conventional full-scale PC construction that introduces large prestresses, namely full prestressing (YPC) and partial prestressing (:
Prestressed reinforced concrete (PRO) construction is considered as an intermediate structure between K, Re construction, and PO construction other than ppo) ilti, and its design standards and construction guidelines have recently been established in Ministry of Construction notifications and other documents. Although this method introduces mild prestress, it does not require large-scale equipment or setup9, and quality and construction management are relatively easy. When utilized, it can have remarkable effects on improving the strength and toughness of reinforced concrete structures, preventing cracks and deflection, reducing the thickness and weight of slabs and slabs, securing long span spaces, and improving the quality of buildings. Moreover, since it does not require much cost, it is expected to be developed in the future as an effective structural method that can be easily used.

The present invention aims to double the above merits by further rationalizing the design and simplifying the construction by devising the PA misstrand arrangement and its tensioning method. Explain in detail.

First, the lower end fixing parts 4a of the PO strands are attached to the four corners of the pillars 1 that will rise up in a reinforced concrete foundation or foundation 2, the fixing fittings 4b are attached to the lower ends, and the joint fittings 4j are attached to the upper ends, and then buried. do. After pouring concrete for the foundation and foundation base, main reinforcement 1a and hoop 1 of column 1 on the lowest floor
Inside b, each floor is bent in an X-shape in the diagonal direction of the column cross section, and a steel pipe sheath 5 with a built-in PC strand 4 is built by continuously bending multiple floors, and the lower end of the PC strand 4 is connected to a joint fitting 4j.
The steel pipe sheath 5 is held in the correct position by connecting to the steel pipe sheath 5, and the concrete for the lowest floor is poured. In this case, at the joint with the large bar 3 at the upper end of the column on the lowest floor, the steel pipe sheath 5 is generally located just inside the main reinforcing bars at the four corners of the column 1, as shown in FIGS. 1 and 2. The outer sides of the intersecting large bar 9 main reinforcements 3a are vertically raised, and then on the upper floor, they are similarly bent in the diagonal direction of the column cross section and arranged in an X shape.

The arrows (-same→) in FIG. 1 indicate the direction of this X shape in the horizontal projection plane. On the upper floor as well, the steel pipe sheath 5 containing the PC strands 4 is held at a regular position, and the required reinforcement and concrete placement are performed, and the same operations are repeated to construct a desired plurality of floors. After the required strength of the concrete has been achieved, the upper end of the PC strand inside the steel pipe sheath is tensed with a jack or the like at the top of the concrete and fixed with a fixing fitting, and then the column base on the lowest floor is fixed. By pressurizing the grout material into the steel pipe sheath 5 using a pump until it overflows from the upper end, the gap between the PC strand 4 and the inner surface of the steel pipe sheath 5 is completely filled with the grout material over the entire length. This introduces vertical prestress into the concrete of this multi-story column.

Note that the amount of prestress to be introduced can be freely adjusted by selecting the pole type and diameter of the PO strand and the magnitude of its tension. When building a high-rise building with a large number of lii#s, it is difficult to separate them into sections of 2 to 311# or several floors, and above that, connect the PO bus tondo with one-hand metal fittings and build the frame, while building the second and subsequent floors. All you have to do is go nervously. In this case, the tension of the PO strands at each level does not have to be the same as the PO strands at several levels; for example, the higher the PO strand, the more
By gradually thinning the strands and reducing the tension, the prestressed lids on each floor can be opened to the desired height. By introducing prestressing, tensile strength of reinforced concrete construction
Since it is well known that the bending shear strength is improved and cracks do not occur, the explanation will be omitted. However, in order to deal with the compressive force, it is necessary to increase the compressive stress of the concrete by the amount of prestress due to the tension of the PC strands, but since this value is generally about 10 to 50qr7td, it is necessary to increase the concrete used by slightly increasing the amount of cement per unit. It can be easily done by adjusting the mixture of
You can also make the song a little thicker.

Next, one of the features of the present invention is that the PO strands are arranged in an X-shape in the diagonal direction of the cross-section of each floor column, and the significance and advantages thereof will be listed, and the synergistic effect of the X-shape device and prestressing will be explained. To summarize, (υ) First, by arranging each floor in an X-shape, the PO strands simultaneously act as a place or truss, increasing the shear and bending strength of the columns accordingly.

(2) Furthermore, by placing them in the diagonal direction of the column cross section, each strand effectively works as a place or truss for horizontal loads in both the x-x direction and the y-y direction, so the minimum number of strands is 4. The po strands can handle seismic loads from all directions.

(3) In general, PO strands! 111! A narrow place like the one will buckle immediately and become ineffective against a compressive load, so only one tension side place is effective, but in this case, the initial tension is given by the tension, so it will not work against a horizontal external force. Not only the tension-side place but also the contraction-side place are used only in the tension region, so no compressive stress is generated. The reduction in tension on the M-side place also contributes to the horizontal strength as if the compression place were tensing, so it is twice as effective as a general place that does not have tension.

(The yield load and tensile strength of 4JPO strands is several times higher than that of reinforcing bars or general steel materials, so it can be used as a place easily with a small amount of steel, and can be easily accommodated in a column cross section of normal dimensions.) It is compact and economical.

(5) Reinforced concrete structures have the disadvantage of being hard, brittle, and lacking in toughness, but by applying this tension press, it is possible to control cracks in the columns, suppress the growth of cracks even after they occur, and reduce the width of the cracks once the external force is removed. Since the column closes and restores its structure, the toughness of the column is dramatically improved.

(67) Therefore, if this prestressed concrete blue color with PC strands that can be used as an omnidirectional place is used to design well, high-rise or supercrystalline buildings, which are generally difficult to design without steel reinforced concrete or steel structures, can be built without using steel frames. It can be constructed economically and in a short construction period.

(Even when viewed from above, the four P
Since you only need to insert c-strands and tension and grout multiple floors at once, it requires only a small amount of effort compared to its great effect.

It is a construction method that can economically increase the strength and toughness of reinforced concrete columns in buildings and other structures using basic steel materials and simple construction.

Although the most typical example has been described above, P.
The direction of the C strand is not necessarily limited to the diagonal direction of the cross section of the column, and the direction and meaning thereof shall include all variations. That is, for example, if you want to strengthen M in only one direction of a building, use 5 as shown in Figure 3(a).
It is sufficient to place the KPO strands in one direction with respect to the column cross-section in a single or multiple X-shape on each floor and tension them.Also, when reinforcing both directions of
), it is also possible to insert as many PC strands as necessary in an X-shape parallel to the X-X@7-7 axis.

[Brief explanation of the drawing]

The first factor is a cross-sectional view of a tensioned prestressed concrete column incorporating PO strands according to the present invention in an X shape.
The figure is a longitudinal cross-sectional view thereof, and FIG. 3 is a cross-sectional view of a different embodiment. 1...Column 1a...Column main reinforcement 1b...7-pu 2...Foundation base...Large bar 9 3a...Large bar main reinforcement 4. ...PO strand 4 & ... Lower end anchoring part 4b of PC strand ... Fixed fitting 4j ... Joint fitting 5 ......m Pipe sheath 1, Incident display Tokusho, l -F -39'f'〆2, Name of invention PC Punto JSX? f'>h self'f#'l'AI&,
Presto L21-Kushifree 1, Ensha 3, Relationship with the person making the amendment Patent applicant's name: Stock company; Tsuchi Konoike Group (IVI,...) 4, Agent: Showa month, day, day, day, day, year, year 1, name of the invention, PC Prestressed concrete columns with built-in tendons in an X-shape 2% Scope of claim For reinforced concrete columns, the fixed collapsed portion of the lower end of the PC tendon is buried in the foundation or foundation beam directly under the column foot on the lowest floor. Then, in the diagonal direction of the column cross section or in any other direction, a steel pipe sheath with a PC tendon placed inside is arranged inside the main reinforcement of the column and 7-no. After concrete is poured and F9T strength is developed, the upper end of the PC tendon is fixed under tension at the top of the above multiple floors, and grout is press-filled into the steel pipe sheath.
Tensioned prestressed concrete columns with built-in X-shaped PC tendons. 6 DETAILED DESCRIPTION OF THE INVENTION The present invention effectively improves the strength and toughness of reinforced concrete columns in a simple manner. Originally, it is a reinforced concrete structure (hereinafter abbreviated as "RC structure")
Compared to steel-framed columns, columns generally have the disadvantage that their strength rapidly decreases when cracks occur. On the other hand, steel-framed columns are strong against tension and bending, but are weak against pressure buckling, and have the disadvantage that fire-resistant coatings and anti-corrosion coatings are time-consuming and time-consuming. Generally speaking, steel-framed reinforced concrete columns are often used for high-rise buildings to take advantage of this 1Ibl advantage and supplement short shields, but this is more labor-intensive and considerably more expensive than RC columns. In addition, prestressed concrete construction (hereinafter abbreviated as “PC construction”)
A pillar can be considered, but this requires large-scale equipment and setup, strict quality and construction management, and special technology to make full use of them, and it takes a long time and construction time, so it is especially important to avoid stress over long spans. At present, it is hardly used in general architecture except in very large special cases. In order to remove this barrier, conventional full-scale PC construction that introduces large prestresses, namely full prestressing (FPC) and
In addition to 4% PC construction, prestressed reinforced concrete (pRe) construction is considered as an intermediate structure between Re construction and PC construction, and its design standards and construction guidelines have recently been established by the Ministry of Construction and other notifications. This is just the introduction of a lightweight frameless system, which does not require large-scale equipment or setup, and quality and construction management are relatively easy. structural strength. Improves toughness, prevents cracking and deflection, and forms a bond. It has remarkable effects on reducing slab thickness and weight, securing long-span spaces, and improving building quality.Moreover, it does not cost much, so it is expected to develop in the future as an easy-to-use and effective structural method. It is something that ' The present invention is based on the beat or paw bar (hereinafter collectively referred to as "
By devising the arrangement of PC tendons (called "PC tendons") and the method of tensioning them, we further streamlined the design and simplified construction, thereby doubling the above-mentioned benefits. This will be explained in detail. First, install PC tendons at the four corners of the pillar l that will rise from the anchor or foundation beam 2 made of reinforced concrete.
A fixed angle fitting 4b is attached to the lower end of the F-end fixed end portion slip portion 4a, and a joint fitting 4j is attached to the upper end thereof, and these are buried. After pouring concrete for the foundation and foundation beam, each floor is laid in an
Continuously bend multiple floors, build a steel pipe sheath 6 with a built-in PC tendon 4, and connect the lower end of the PC tendon 4 with a fitting 4j.
The steel pipe sheath 6 is held in the correct position by connecting to the steel pipe sheath 6, and the concrete for the lowest floor is poured. In this case, at the junction with the large beam 8 at the upper end of the column L, the copper pipe sheath 6 is generally located just inside the main reinforcing bars at the four corners of the column L, as shown in FIGS. 1 and 2. The outside of the main pillar i8a that intersects is vertically raised, and then on the upper floor, it is similarly bent in the diagonal direction of the column cross section and arranged in an X shape. The arrows (, ---) in FIG. 1 indicate the direction of this X shape in the horizontal projection plane. On the upper floor as well, the steel pipe sheath 5 containing the PC tendons 4 is held in a regular position, and the required reinforcement and concrete pouring are carried out, and the same operations are repeated to construct a desired plurality of floors. After the strength of the concrete has been developed, the upper end of the PC tendon in the steel pipe sheath is tensed with jacks etc., and then the column base on the lowest floor is tightened. By press-fitting the cloud material into the steel pipe sheath 6 from the upper end using a pump until it overflows from the upper end, the PC tendon 4 and the steel pipe sheath 5 are
The gap with the inner surface of the grout is completely filled along its entire length with grout. As a result, the concrete of this multi-story column will be press-lessed in the vertical direction. Note that the amount of prestress to be introduced can be freely adjusted by selecting the type and diameter of the PC tendon and the magnitude of its tension. For high-rise buildings with many floors, 2~
Divide the building into 8 floors or several floors at a time, and then connect the PC tendons with fittings and build the frame while building the structure and tension the second and subsequent floors. Bye. In this case, the tension force of the PC tendons on multiple floors of each board does not have to be the same; for example, the PC tendons can be made thinner as they go up to reduce the tension force, and the amount of prestress introduced on each floor can be adjusted to a desired value. I can control it. It is well known that the introduction of prestressing improves the tensile, bending, and shear strength of reinforced concrete columns and prevents the occurrence of cracks, so the explanation will be omitted. However, regarding the pressure force, it is necessary to increase the compressive stress of the concrete by the amount of prestress due to the tension of the PC tendons, but this value is generally lO
Since it is about ~6011 ipf/F, it can be easily done by adjusting the mix of concrete used, such as by slightly increasing the amount of cement per unit, or by making the cross section of the column considerably thicker. Next, arranging PC tendons in an X shape in the diagonal direction of the cross section of each floor column is one of the 4ik [k] of this article, and its significance and origin will be listed. To summarize the synergistic effects, etc., (1) Firstly, by arranging them in an X-shape on each floor, the PC tendons simultaneously act as places or trusses, and the strength of the pillars and bends increases accordingly. (2) By inserting the fibers in the diagonal direction of the column cross section, each tendon effectively works as a place or truss for the horizontal cargo space in both the x-x direction and the y-x direction, so the minimum number of Due to the four PC tendons, the place will immediately buckle under compressive loads and become ineffective, so only one tension side place will make noise, but in this case, the initial tension is applied by tension. Therefore, in response to horizontal external force, not only the extension side place but also the contraction side place is used only in the tension region, and no compressive stress is generated. The reduction in tension on the contraction-side place also contributes to the horizontal cutting force as if the compression place were exerting tension, so it is twice as effective as a general place without tension. F41PC tendons have yield load and tensile strength several times higher than reinforcing bars or general steel, so they can be used as a place with only a small amount of steel, and can easily fit into a column cross section of normal dimensions, making it economical. It is. (5) Reinforced concrete structures have the disadvantage of being strong, brittle, and lacking in toughness, but by applying this tension placement, it is possible to control cracks in the columns, suppress the growth of cracks even after they occur, and prevent the cracks from forming once the external force is removed. Since the width closes and restores its shape, the toughness of the column improves dramatically. (6) Therefore, by successfully designing prestressed concrete columns using PC tendons that can also be used as omnidirectional places, it is possible to design vortex or high-rise buildings that are generally difficult to design unless they are made of steel-framed reinforced concrete or steel-framed structures.
The steel frame can be installed thoroughly and in a short construction period. (7) From a construction perspective, it is just a matter of putting four PC tendons in a steel pipe sheath and tensing and clouding several floors at once, so it is a terrible hassle compared to the great effect. That's enough. This is a construction method that can economically increase the strength and toughness of reinforced concrete columns in buildings and other structures by using a small amount of copper phase and simple construction. Although the most typical example has been described above, P.
The direction of the C tendon is not necessarily limited to the diagonal direction of the column cross section (but the direction and number may include all variations. For example, if you want to reinforce only one direction of a building, ), the PC tendons can be placed in one direction with respect to the pillar surface, and each floor can be placed in a single or number of boards in an X shape and tensioned.
Even when reinforcing both the X and 7-7 directions, as shown in FIG. 8(b), the required amount of PC tendons may be inserted in an X shape parallel to the x-x and y-y axes. 4. Brief explanation of the drawings Fig. 1 is a cross-sectional view of a prestressed concrete column with PC tendons according to the present invention covered in an X-shape, Fig. 2 is a cross-sectional view of the 11111 section, and Fig. 8 is a different cross-sectional view. FIG. 100. Pillar 1a06. Column main reinforcement lb, , hoop 210. Basic fee 800. Large burr 8a, 1. Large burr main bar 400. PC tendon 4a, , PC tendon lower end constant depth part 4b, 00 foot fitting 4j, , i hand fitting 5, ,, Th! Sheath patent applicant: Wakabayashi 1 Patent user: Hiroshi Minami − Patent applicant: Konoike Co., Ltd. 1 person outside the group

Claims (1)

[Claims] For reinforced concrete columns, bury the anchoring part of the lower end of the PA misstrand in the foundation or foundation base directly under the column foot of the lowest floor, and then install each floor in the diagonal direction of the column cross section or in other directions. A steel pipe sheath with built-in PC strands is placed on the inside of the main reinforcement of the column and the hoop in an X-shape on several consecutive floors, and after concrete is poured and the required strength is achieved, PC strands are installed at the top of the multiple floors. The upper end of the strand is fixed under tension, and grout is press-fitted into the steel pipe sheath.A prestressed, concrete column with an X-shaped built-in PC bath.