JPH0124195Y2 - - Google Patents
Info
- Publication number
- JPH0124195Y2 JPH0124195Y2 JP1984143848U JP14384884U JPH0124195Y2 JP H0124195 Y2 JPH0124195 Y2 JP H0124195Y2 JP 1984143848 U JP1984143848 U JP 1984143848U JP 14384884 U JP14384884 U JP 14384884U JP H0124195 Y2 JPH0124195 Y2 JP H0124195Y2
- Authority
- JP
- Japan
- Prior art keywords
- pile
- concrete
- reinforcement
- spiral reinforcement
- piles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000002787 reinforcement Effects 0.000 claims description 21
- 239000004567 concrete Substances 0.000 claims description 19
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- 238000000465 moulding Methods 0.000 claims description 3
- 239000011150 reinforced concrete Substances 0.000 claims 1
- 230000003014 reinforcing effect Effects 0.000 description 15
- 238000005452 bending Methods 0.000 description 12
- 230000007935 neutral effect Effects 0.000 description 6
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000011513 prestressed concrete Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Landscapes
- Reinforcement Elements For Buildings (AREA)
- Piles And Underground Anchors (AREA)
- Rod-Shaped Construction Members (AREA)
Description
〔産業上の利用分野〕
本考案は、構造物の基礎杭に適したパイル、殊
にPCパイルを強化した強化パイルに関するもの
である。
〔従来の技術〕
従来、この種構造物の基礎杭における頭部補強
に関するものとして、特開昭57−178026号公報に
開示された発明がある。
これは、複数本の垂直状の主筋と、これら各主
筋をたがいに結合するらせん状の帯筋とから構成
した補強筋であり、この補強筋を基礎杭の頭部中
央孔内に下部を挿入することにより基礎杭の頭部
を強化しようとする発明である。
しかし、上記発明のものは、補強筋を基礎杭の
頭部中央孔内にその下部を単に挿入するだけの構
造であるため、基礎杭と補強筋とは夫々単独に機
能するに過ぎず、両者一体構造になることによる
相乗効果は期待できない。
すなわち、地震等により基礎杭に水平荷重がか
かつた場合に、その荷重は先ず基礎杭に作用し、
次に杭の許容範囲を越える剪断力や曲げモーメン
トが起生した時に、杭の内部に挿入した補強筋に
作用することになる。したがつて、このような事
態が生じた時には、基礎杭は既に損傷してしまつ
ている場合があるといつた問題点がある。
このうよな従来の問題点を解決するため、出願
人は先に、実開昭59−5642号公報に示す如き考案
を提案した。
これは、中空コンクリートパイルの軸筋や該軸
筋に巻いたらせん筋等に、補強鉄筋を溶接などの
手段をもちいて固着して該補強鉄筋をパイルの中
空部内に突出せしめてなる中空コンクリートパイ
ルと、該中空部にコンクリートを充填して上記補
強鉄筋を埋設し、該補強鉄筋を介して両者の一体
化を図つたパイルである。
〔考案が解決しようとする問題点〕
これにより、上記特開昭57−178026号公報に開
示された発明が有する問題点は解決できたが、コ
ンクリートパイルを遠心成形によつて形成する前
工程において、補強鉄筋をその軸筋や該軸筋に巻
いたらせん筋等(鉄筋篭)に溶接などで固着する
加工工程が必要であり、作業性及びコストの点に
おいて問題があつた。
〔問題点を解決するための手段〕
本考案は、上記実開昭59−5642号公報に示す如
き考案にさらに改良を加えたものであり、その要
旨とするところは、垂直で平面視円形状に配設し
た複数本のPC鋼棒と、これら複数本のPC鋼棒に
よつて形成した筒状体の外周にらせん状に巻き付
け、各PC鋼棒と接点で結合せしめたらせん筋と
を芯にして、遠心成型によつて形成したPCパイ
ルの中空部に第2のらせん筋とコンクリートを装
填し、該コンクリートを介して前記PCパイルと
第2のらせん筋を芯とする中込めコンクリート部
とを一体的に形成したことを特徴とする強化パイ
ルにある。
〔実施例〕
一般に、基礎杭と構造物とは、フーチングを介
して連結されるのであるが、最近の地震工学的研
究によれば、大型地震の際の建造物の共振を含め
た大きな水平動によつて、上記基礎杭、殊に地表
近くの基礎杭には予想外に大きな水平荷重が作用
し、これによる許容範囲を越える大きなせん断力
及び曲げモーメントの起生によつて、甚だしい場
合は杭の折損などが生じることが判明した。
この対策としては、大径のPCパイルを用い、
且つ又その本数を増加させることが当然考えられ
るが、これは地質、工法、コスト等の関係で限度
がある。
一方、考案者の属する出願人における研究によ
れば、従来用いられてきた円筒形PCパイルは、
前記水平荷重(パイルと直角方向の荷重)に対し
基本的に弱点があることが明らかとなつた。
すなわち、第1表の如き諸元の外径30センチメ
ートル、長さ2.7メートルの高強度PCパイルを両
端支持して中央に集中荷重を加えた場合の試験結
果から、らせん筋2の量が少ない時せん断破壊を
起こし易いことが判明したほか、前記のように荷
重をかけたときのパイル断面における中立軸位置
が、第4図の如く、軸力Aが35トンのものでは曲
率ψが5,10,15,及び20(以上、各々×10-4)
のときのいずれも、中空部4aの上縁付近となる
ので、第6図に示すように、曲げ強度(モーメン
ト)Mは曲率20×10-4付近でも高い数値を維持す
るが、軸力Aが70トンのものでは、第6図のよう
に、曲率12×10-4付近で圧縮側(第5図の図形上
の水平中心線より上方)で圧壊を起こし、以後の
中立軸位置が引張側に移動する結果(第5図)、
曲げ強度は前記第6図一点鎖線の如く急激に低下
し、遂に曲げ圧壊することが判明したのである。
[Industrial Application Field] The present invention relates to piles suitable for foundation piles of structures, particularly reinforced piles made by strengthening PC piles. [Prior Art] Conventionally, there is an invention disclosed in Japanese Unexamined Patent Application Publication No. 178026/1983, which relates to reinforcing the head of a foundation pile of this type of structure. This is a reinforcement consisting of multiple vertical main reinforcements and a spiral tie reinforcement that connects these main reinforcements to each other.The lower part of this reinforcement is inserted into the center hole of the head of the foundation pile. This invention aims to strengthen the heads of foundation piles by doing this. However, the above invention has a structure in which the lower part of the reinforcing bar is simply inserted into the center hole of the head of the foundation pile, so the foundation pile and the reinforcing bar only function independently, and both No synergistic effects can be expected from an integrated structure. In other words, when a horizontal load is applied to a foundation pile due to an earthquake, etc., the load first acts on the foundation pile,
Next, when a shearing force or bending moment that exceeds the allowable range of the pile occurs, it will act on the reinforcing bars inserted inside the pile. Therefore, there is a problem in that when such a situation occurs, the foundation piles may have already been damaged. In order to solve these conventional problems, the applicant previously proposed a device as shown in Japanese Utility Model Application Publication No. 59-5642. This is a hollow concrete pile in which reinforcing reinforcing bars are fixed to the shaft reinforcement of the hollow concrete pile or spiral reinforcement wrapped around the shaft reinforcement using means such as welding, and the reinforcing reinforcing bars protrude into the hollow part of the pile. This is a pile in which the hollow portion is filled with concrete and the reinforcing reinforcing bars are buried, and the two are integrated through the reinforcing bars. [Problems to be solved by the invention] As a result, the problems of the invention disclosed in JP-A-57-178026 can be solved; however, in the pre-process of forming concrete piles by centrifugal forming This requires a processing step in which the reinforcing reinforcing bars are fixed by welding or the like to the shaft bars or spiral bars wrapped around the shaft bars (reinforcing bar cages), which poses problems in terms of workability and cost. [Means for solving the problem] The present invention is a further improvement of the invention shown in the above-mentioned Japanese Utility Model Application Publication No. 59-5642, and its gist is that it is vertical and has a circular shape in plan view. The core consists of multiple prestressed steel rods arranged in Then, the second spiral reinforcement and concrete are loaded into the hollow part of the PC pile formed by centrifugal molding, and the filled concrete part having the core of the PC pile and the second spiral reinforcement is formed through the concrete. The reinforced pile is characterized by being integrally formed. [Example] Generally, foundation piles and structures are connected via footings, but according to recent earthquake engineering research, large horizontal movements, including resonance of buildings during large earthquakes, As a result, an unexpectedly large horizontal load acts on the foundation piles mentioned above, especially the foundation piles near the ground surface, and this causes a large shear force and bending moment that exceeds the allowable range, which may cause the pile to fail in extreme cases. It was found that breakage occurred. As a countermeasure, use large-diameter PC piles,
Naturally, it is conceivable to increase the number of them, but there are limits to this due to geology, construction methods, costs, etc. On the other hand, according to research conducted by the applicant to whom the inventor belongs, the cylindrical PC pile that has been used in the past,
It has become clear that there is a fundamental weakness against the horizontal load (load in the direction perpendicular to the pile). In other words, from the test results when a high-strength PC pile with an outer diameter of 30 cm and a length of 2.7 meters with specifications as shown in Table 1 is supported at both ends and a concentrated load is applied to the center, the amount of spiral reinforcement 2 is small. In addition, it was found that when a load is applied as described above, the neutral axis position in the cross section of the pile has a curvature ψ of 5 when the axial force A is 35 tons, as shown in Figure 4. 10, 15, and 20 (each x 10 -4 )
In both cases, the bending strength (moment) M remains high even near the curvature of 20×10 -4 , but the axial force A As shown in Figure 6, in the case of 70 tons, crushing occurs on the compression side (above the horizontal center line on the figure in Figure 5) near the curvature of 12 × 10 -4 , and the subsequent neutral axis position is tensile. As a result of moving to the side (Figure 5),
It was found that the bending strength suddenly decreased as shown by the dashed line in FIG. 6, and finally the bending crushing occurred.
このように構成された本案強化パイル10は、
中空部10a内に第2のらせん筋11を芯にした
中込めコンクリート部12aが形成されており、
且つ該中込めコンクリート部12aとパイル10
とは一体構造となつているので、前記の如き水平
荷重が加わつたときも、これにより生じるせん断
力及び曲げモーメントに対し、前記第2のらせん
筋11及び中込めコンクリート部12aが補強し
て対応し、強度が格段に向上する。
即ち、前述と同様な実験によれば、パイルと直
角に作用する荷重(水平荷重に相当)により生ず
る曲率ψの5,10,15,20(各々×10-4)のいず
れにおいても、中立軸は第2図、第3図に示すよ
うに、断面における上縁から1/3強のところに集
中し、これにより殊に圧縮側での断面積が増加し
て上記圧縮側における最初の圧壊が未然に防止さ
れる。したがつて、曲げ強度(モーメント)は、
第6図実線の如く、曲率20×10-4においても最高
時の80%程度を保ことができる。
〔考案の効果〕
本考案に係る強化パイルは、上述の如く、垂直
で平面視円形状に配設した複数本のPC鋼棒と、
これら複数本のPC鋼棒によつて形成した筒状体
の外周にらせん状に巻き付け、各PC鋼棒と接点
で結合せしめたらせん筋とを芯にして、遠心成型
によつて形成したPCパイルの中空部に第2のら
せん筋とコンクリートを装填し、該コンクリート
を介して前記PCパイルと第2のらせん筋を芯と
する中込めコンクリート部とを一体的に形成した
構成からなるものであるから、パイル打込後地表
近くのパイルに作用する大型地震による水平荷重
に対し、それにより生ずるせん断力に対しては第
2のらせん筋が、又曲げモーメントに対しては中
空部に打設した中込めコンクリート部が各々PC
パイルのらせん筋及びコンクリートを補強して対
応し、これにより曲げによつて生ずる圧縮側の圧
壊を完全に防止し、中立軸をほゞ一定に保持して
高い強度を維持することができる。
したがつて、パイル径又は本数を増加すること
なく、且つコストの上昇を抑えた基礎杭を形成す
ることができ、建造物の大型地震による破壊を防
止できるといつた大なる効果を有する。
The reinforced pile 10 configured in this way is
An embedded concrete portion 12a having a second spiral reinforcement 11 as a core is formed in the hollow portion 10a,
In addition, the filled concrete portion 12a and the pile 10
Since it has an integral structure, even when horizontal loads such as those mentioned above are applied, the second helical reinforcement 11 and the concrete filling part 12a are reinforced to cope with the resulting shear force and bending moment. The strength is greatly improved. In other words, according to an experiment similar to the one described above, the neutral axis is As shown in Figures 2 and 3, it is concentrated at a little more than 1/3 from the upper edge of the cross section, and as a result, the cross-sectional area especially on the compression side increases and the first crushing occurs on the compression side. Prevented in advance. Therefore, the bending strength (moment) is
As shown by the solid line in Figure 6, even at a curvature of 20 x 10 -4 , approximately 80% of the maximum value can be maintained. [Effects of the invention] As mentioned above, the reinforced pile according to the invention includes a plurality of PC steel bars arranged vertically in a circular shape in plan view,
A PC pile is formed by centrifugal molding, with spiral striations that are spirally wound around the outer periphery of a cylindrical body formed by these multiple PC steel bars and connected to each PC steel bar at contact points. It consists of a structure in which a second spiral reinforcement and concrete are loaded into the hollow part, and the prestressed concrete pile and an embedded concrete part having the second spiral reinforcement as a core are integrally formed via the concrete. Therefore, after the pile was driven, a second spiral reinforcement was installed in the hollow part to handle the horizontal load due to a large earthquake that acts on the pile near the ground surface, and to handle the resulting shear force, and to handle the bending moment. Each concrete part is PC
By reinforcing the helical reinforcement of the pile and the concrete, it is possible to completely prevent collapse on the compression side caused by bending, and maintain high strength by keeping the neutral axis approximately constant. Therefore, it is possible to form foundation piles without increasing the diameter or number of piles and to suppress an increase in cost, which has the great effect of preventing buildings from being destroyed by large-scale earthquakes.
第1図は本案強化パイルの打設後の断面図、第
2図、第3図は曲げモーメントを加えられた本案
パイルの中立軸を示す断面図、第4図、第5図は
同PCパイルに曲げモーメントを加えたときの中
立軸を示す断面図、第6図は曲率に対する曲げ強
度(モーメント)の変化を示す図である。
1……PC鋼棒、2……らせん筋、3,9,1
2……コンクリート、10……基礎杭(PCパイ
ル)、10a……中空部、11……第2のらせん
筋、12a……中込めコンクリート部。
Figure 1 is a cross-sectional view of the original reinforced pile after installation; Figures 2 and 3 are cross-sectional views showing the neutral axis of the original pile to which a bending moment has been applied; Figures 4 and 5 are the same PC piles. FIG. 6 is a cross-sectional view showing the neutral axis when a bending moment is applied to the curve, and FIG. 6 is a diagram showing changes in bending strength (moment) with respect to curvature. 1...PC steel bar, 2...Spiral bar, 3,9,1
2... Concrete, 10... Foundation pile (PC pile), 10a... Hollow part, 11... Second spiral reinforcement, 12a... Filled concrete part.
Claims (1)
棒と、これら複数本のPC鋼棒によつて形成した
筒状体の外周にらせん状に巻き付け、各PC鋼棒
と接点で結合せしめたらせん筋とを芯にして、遠
心成型によつて形成したPCパイルの中空部に第
2のらせん筋とコンクリートを装填し、該コンク
リートを介して前記PCパイルと第2のらせん筋
を芯とする中込めコンクリート部とを一体的に形
成したことを特徴とする強化パイル。 Multiple prestressed steel bars arranged vertically in a circular shape in plan view, wrapped spirally around the outer periphery of a cylindrical body formed by these multiple prestressed steel bars, and connected to each prestressed steel bar at contact points. A second spiral reinforcement and concrete are loaded into the hollow part of the PC pile formed by centrifugal molding, with the spiral reinforcement as the core, and the PC pile and the second spiral reinforcement are connected to the core through the concrete. A reinforced pile characterized by being integrally formed with a reinforced concrete part.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1984143848U JPH0124195Y2 (en) | 1984-09-22 | 1984-09-22 |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1984143848U JPH0124195Y2 (en) | 1984-09-22 | 1984-09-22 |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6158235U JPS6158235U (en) | 1986-04-19 |
JPH0124195Y2 true JPH0124195Y2 (en) | 1989-07-24 |
Family
ID=30702139
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP1984143848U Expired JPH0124195Y2 (en) | 1984-09-22 | 1984-09-22 |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0124195Y2 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57178026A (en) * | 1981-04-25 | 1982-11-02 | Noboru Hattori | Reinforcing rod for foundation pile head |
JPS595642B2 (en) * | 1979-02-23 | 1984-02-06 | 昭和ケ−・ビ−・アイ株式会社 | Manufacturing method of tantalum powder |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS595642U (en) * | 1982-06-30 | 1984-01-14 | 前田製管株式会社 | concrete pile |
-
1984
- 1984-09-22 JP JP1984143848U patent/JPH0124195Y2/ja not_active Expired
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS595642B2 (en) * | 1979-02-23 | 1984-02-06 | 昭和ケ−・ビ−・アイ株式会社 | Manufacturing method of tantalum powder |
JPS57178026A (en) * | 1981-04-25 | 1982-11-02 | Noboru Hattori | Reinforcing rod for foundation pile head |
Also Published As
Publication number | Publication date |
---|---|
JPS6158235U (en) | 1986-04-19 |
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