JP2004084312A

JP2004084312A - Reinforcing member of concrete building

Info

Publication number: JP2004084312A
Application number: JP2002246954A
Authority: JP
Inventors: Tomohisa Ogata; 小方　智寿; Tomoyasu Kato; 加藤　友康; Toshitaka Ishizawa; 石澤　俊崇; Takashi Hattori; 服部　高志
Original assignee: Kajima Corp; Hitachi Metals Ltd
Current assignee: Kajima Corp; Proterial Ltd
Priority date: 2002-08-27
Filing date: 2002-08-27
Publication date: 2004-03-18

Abstract

<P>PROBLEM TO BE SOLVED: To provide reinforcing members of a concrete building preventing the complication of a design even if the reinforcing members frictionally coming into press-contact with reinforcement and a fixing hardware are used. <P>SOLUTION: In the reinforcing members of the concrete building frictionally coming into press-contact with the reinforcement 12 and the fixing hardware 11, when a tension test is performed by holding a joint section between the reinforcing members, it is fractured with the reinforcement 12. An area of an alignment face of the joint section between the reinforcement 12 and the fixing hardware 11 is 1.01 to 3.00 times as large as an area of a vertical section in the direction of the axis of the reinforcement. At least part of the alignment face of the joint section is formed in a taper-shape or a semi-spherical recess-shape. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、コンクリート建築物の補強部材に関する。
【０００２】
【従来の技術】
図１０（ａ）（ｂ）は、コンクリート構造物の補強部材（以下、「コンクリート構造物の補強部材」を略して「補強部材」という）を配設した模式断面図である。従来から、図１０に示すように（ａ）柱１０３には柱主筋１０２ａ、（ｂ）梁１０４には梁主筋１０２ｂが配設されている。そして、柱主筋１０２ａと梁主筋１０２ｂにはネジ節鉄筋や異形鉄筋が用いられ、その端部には、コンクリートへの定着性と、圧縮強さおよび引張り強さを高めるために定着金物１０１ａ、１０１ｂがそれぞれ取り付けられている。
【０００３】
摩擦圧接を利用して、定着プレートに異形鉄筋を取り付ける補強部材の従来例について説明する。図９は、特開２００１−１２０１２号公報に開示される定着プレートへの異形鉄筋の取り付け構造の側面図である。図９で、異形鉄筋９２の先端には、異形鉄筋９２と同軸上で外周に雄ネジを形成した鋼製の雄ネジ部材９３を摩擦圧接で接合し、雄ネジ部材９３を定着プレート９１の孔に挿通し、雄ネジ部材９３の雄ネジに螺合した２個のナット９４で雄ネジ部材９３上に定着プレート９１を取り付けている。なお、９５は圧接部である。この特開２００１−１２０１２号公報によれば、鉄筋の種類がネジ節鉄筋に限定されず、また、雄ネジ部材に螺合するナットも通常の機械構造で用いられる市販品が使用可能となり、外形寸法もネジ節鉄筋に螺合されるナットに比べて小さくなるので、柱主筋や梁主筋のコストダウンが図れ、また、配設上も有利であるとしている。
【０００４】
本発明者らは、特開２００１−１２０１２号公報に開示されるコンクリート建築物の補強部材の問題点を鑑みて、例えば、図８に示すような異形鉄筋８２の端部に円板形状の定着金物８１を摩擦圧接によって直接接合することを特徴とするコンクリート建築物の補強部材８０を発明し、特願２００１−２２９６０６号において出願した。
【０００５】
【発明が解決しようとする課題】
しかしながら、特願２００１−２２９６０６号の発明の補強部材は、定着金物に機械構造用炭素鋼などの鋼材を用いた場合、前記鋼材の材料の強度よりも鉄筋の材料の強度が大きくなると、接合部を挟んで引張試験を行ったときに接合部で破断する場合があった。ここで、接合部とは、定着金物と鉄筋のそれぞれの摩擦圧接による熱影響部および接合面によって構成される部位を指す。コンクリート建築物の設計において鉄筋よりも低強度の接合部が存在すると、接合部と鉄筋の両方の強度を考慮しなければならないので設計が煩雑になり、さらに高強度鉄筋の性能を十分に発揮できないという問題があった。
【０００６】
また、上記補強部材において、定着金物の材料の強度が鉄筋の材料の強度より大きい場合においても、接合部の強度が摩擦圧接時の熱影響により鉄筋の材料の強度より劣る場合は、やはり接合部を挟んで引張試験を行ったときに接合部で破断するおそれがあった。このために上記と同様に設計が煩雑になるという問題があった。
【０００７】
本発明は上記課題に鑑みてなされたものであって、鉄筋と定着金物とを摩擦圧接した補強部材を用いても設計が煩雑とならない補強部材を提供することにある。
【０００８】
【課題を解決するための手段】
上記課題を解決するため、本発明の鉄筋と定着金物とが摩擦圧接されたコンクリート建築物の補強部材は、接合部を挟んで引張試験を行ったときに、鉄筋で破断することを特徴とする。鉄筋で破断することで、接合部の強度は鉄筋と同等以上とみなすことができ、鉄筋の強度を用いてコンクリート建築物の設計を行うことができるので、設計が簡便になる。また、本発明の補強部材はより強度が必要とされる部位に使用でき、高強度鉄筋の特徴を生かすことも可能となる。
【０００９】
また、本発明の補強部材においては、前記鉄筋と定着金物との接合部の接合面の面積（以下、「接合部の接合面の面積」を略して「接合面積」という）が鉄筋の軸方向垂直断面の面積の１．０１〜３．００倍の面積であることが好ましい。鉄筋の単位面積当たりの引張強度に対して、定着金物と鉄筋との接合部の単位面積当たりの引張強度は低いが、接合面積を鉄筋の軸方向垂直断面の面積の１．０１倍以上として、接合面積を大きくすることにより、接合部の軸方向の引張強度を向上することができる。一方、接合面積を鉄筋の軸方向垂直断面の面積の３．００倍よりも大きくすると、摩擦圧接前の鉄筋および定着金物の準備に工数を要するとともに、鉄筋の中心軸と定着金物の接合面とでなす角度が小さくなりすぎるため、摩擦圧接時に、定着金物と鉄筋との接合面に軸方向の圧着力（接合面を押付ける圧力）が不足して、摩擦圧接時に接合がうまくいきにくくなる。より好ましい範囲は、鉄筋と定着金物との接合部の接合面の面積が鉄筋の軸方向垂直断面の面積の１．５〜２．５倍の面積である。
【００１０】
また、本発明の補強部材においては、接合部の接合面の少なくとも一部がテーパ状または半球状の凹形状であることが好ましい。例えば、テーパ状または半球状の凹形状の定着金物と、軸方向にほぼ垂直な端面を有する鉄筋とを摩擦圧接すると、摩擦熱により、主に接合部の熱容量の小さい鉄筋に材料の軟化が生じ、鉄筋は定着金物の凹形状に沿って変形し、接合部の形状は接合前の定着金物の凹形状に近い形状となって接合が完了する。接合部の接合面がテーパ状または半球状の凹形状となることで、定着金物と鉄筋とが何れも軸方向に垂直な端面同士の接合に比べ接合面積を増加させることができ、その結果、接合部の強度が増加する。
【００１１】
【発明の実施の形態】
以下、発明の実施の形態を実施例に基づいて詳細に説明する。なお、試験に供した定着金物と鉄筋の材料の種類（材質）と引張強さを表１にまとめて示す。また、試験に供した鉄筋の呼び径はＤ２５である。
【００１２】
【表１】

【００１３】
（実施例１）
実施例１を、図１および図７に基づき説明する。材料は、定着金物および鉄筋で、それぞれ機械構造用炭素鋼Ｓ４５Ｃ焼準材およびＳＤ４９０である。
【００１４】
図１は、（ａ）異形鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接中、（ｃ）摩擦圧接後の補強部材の各断面図であり、また図７は、異形鉄筋と定着金物とを摩擦圧接している摩擦圧接装置の模式図である。図１（ａ）で、定着金物１１には、軸中心部に、正面１１ｄから端面１１ｅまで貫通する連通孔１１ｃを形成している。また、異形鉄筋１２との接合部となる接合面をテーパ状の凹形状１１ｂに形成している。異形鉄筋１２は、山形１２ａが形成されており、端面１２ｂで所定長さに切断している。異形鉄筋１２の端面１２ｂは鋸等で切断したままの状態で摩擦圧接が可能で、切断によって生じる凹凸や面の垂直度の管理は必要ない。
【００１５】
一方、図７に示す摩擦圧接装置は、機台７１と、この機台７１上で油圧シリンダ７３により往復移動すると共に電動機７４で回転駆動される主軸７５と、この主軸７５の端部で定着金物１１を把持するチャック７６と、異形鉄筋１２を把持固定する取付具７７などからなる。
【００１６】
異形鉄筋１２と定着金物１１との摩擦圧接は次のとおり行う。先ず、定着金物１１をチャック７６で把持し、また取付具７７に異形鉄筋１２の端面１２ｂを突出して固定する。次に、電動機７４を回転して回転力を主軸７５に伝達し、油圧シリンダ７３により定着金物１１を異形鉄筋１２側（図では右側）に移動する。そして、図１（ｂ）に示すように、異形鉄筋１２の端面１２ｂに定着金物１１を回転しつつ接合面である凹形状１１ｂを接触させて摩擦発熱させる。この摩擦発熱工程では、定着金物１１および異形鉄筋１２の材質に応じた摩擦速度、摩擦圧力、摩擦時間を適宜選定する。次に、電動機７４を停止しかつブレーキ（図示せず）により主軸７５を急停止させ、アプセット圧力を付与する。このアプセット工程では、定着金物１１および異形鉄筋１２の材質に応じたアプセット圧力、アプセット時間を適宜選定する。これにより、図１（ｃ）に示すように、定着金物１１と異形鉄筋１２とが、接合面がテーパ状の凹形状の接合部１３で一体となった補強部材１０となる。
【００１７】
摩擦圧接により定着金物１１に形成した連通孔１１ｃに摩擦圧接時のバリ１４が出てくるので、このバリ１４を定着金物１１の正面１１ｄ方向から目視することによって、摩擦圧接が確実に行われていることがわかり、コンクリート建築物に配設する前にその信頼性が容易に確認できる。
【００１８】
（実施例２）
図２は、実施例２での、（ａ）ネジ節鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の補強部材の各断面図である。材料は、定着金物および鉄筋で、それぞれ機械構造用炭素鋼Ｓ４５Ｃ焼入焼戻材およびＳＤ６８５である。図２（ａ）で、定着金物２１は、ネジ節鉄筋２２との接合部となる接合面をテーパ状の凹形状２１ｂに形成している。ネジ節鉄筋２２はネジ山２２ａが形成されており、端面２２ｂで所定長さに切断している。ネジ節鉄筋２２の端面２２ｂは鋸等で切断したままの状態で摩擦圧接が可能で、切断によって生じる凹凸や面の垂直度の管理は必要ない。
【００１９】
実施例２も、図７に示す摩擦圧接装置により、定着金物２１とネジ節鉄筋２２とを摩擦圧接している。摩擦圧接後、図２（ｂ）に示すように、定着金物２１とネジ節鉄筋２２とが接合面がテーパ状の凹形状の接合部２３で一体となった補強部材２０となる。
【００２０】
（実施例３）
図３は、実施例３での、（ａ）ネジ節鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の補強部材の各断面図である。材料は、定着金物および鉄筋で、それぞれ機械構造用炭素鋼Ｓ４５Ｃ焼入焼戻材およびＳＤ６８５である。図３（ａ）で、定着金物３１には、軸中心部に、正面３１ｄから端面３１ｅまで貫通する連通孔３１ｃを形成している。また、ネジ節鉄筋３２との接合部となる接合面を半球状の凹形状３１ｂに形成している。ネジ節鉄筋３２はネジ山３２ａが形成されており、端面３２ｂで所定長さに切断している。ネジ節鉄筋３２の端面３２ｂは鋸等で切断したままの状態で摩擦圧接が可能で、切断によって生じる凹凸や面の垂直度の管理は必要ない。
【００２１】
実施例３も、図７に示す摩擦圧接装置により、定着金物３１とネジ節鉄筋３２とを摩擦圧接している。摩擦圧接後、図３（ｂ）に示すように、定着金物３１とネジ節鉄筋３２とが接合面が半球状の凹形状の接合部３３で一体となった補強部材３０となる。また、定着金物３１に形成した連通孔３１ｃに摩擦圧接時のバリ３４が出てくるので、このバリ３４を定着金物３１の正面３１ｄ方向から目視することによって、摩擦圧接が確実に行われていることがわかり、コンクリート建築物に配設する前にその信頼性が確認できる。
【００２２】
（比較例１）
図４は、比較例１での、（ａ）異形鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の補強部材の各断面図である。材料は、定着金物および鉄筋で、それぞれ機械構造用炭素鋼Ｓ４５Ｃ焼準材およびＳＤ４９０である。図４（ａ）で、定着金物４１には、軸中心部に、正面４１ｄから端面４１ｅまで貫通する連通孔４１ｃを形成している。また、異形鉄筋４２との接合部となる接合面を、平面からなる端面４１ｅとしている。異形鉄筋４２は、山形４２ａが形成されており、端面４２ｂで所定長さに切断している。異形鉄筋４２の端面４２ｂは鋸等で切断したままの状態で摩擦圧接が可能で、切断によって生じる凹凸や面の垂直度の管理は必要ない。
【００２３】
比較例１も、図７に示す摩擦圧接装置により、定着金物４１と異形鉄筋４２とを摩擦圧接している。摩擦圧接後、図４（ｂ）に示すように、定着金物４１と異形鉄筋４２とが接合部４３で一体となった補強部材４０となる。
【００２４】
（比較例２）
図５は、比較例２での、（ａ）ネジ節鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の補強部材の各断面図である。材料は、定着金物および鉄筋で、それぞれ機械構造用炭素鋼Ｓ４５Ｃ焼入焼戻材およびＳＤ６８５である。図５（ａ）で、定着金物５１には、軸中心部に、正面５１ｄから端面５１ｅまで貫通する連通孔５１ｃを形成している。また、ネジ節鉄筋５２との接合部となる接合面をテーパ状の凹形状５１ｂに形成している。ネジ節鉄筋５２は、ネジ山５２ａが形成されており、端面５２ｂで所定長さに切断している。ネジ節鉄筋５２の端面５２ｂは鋸等で切断したままの状態で摩擦圧接が可能で、切断によって生じる凹凸や面の垂直度の管理は必要ない。
【００２５】
比較例２も、図７に示す摩擦圧接装置により、定着金物５１とネジ節鉄筋５２とを摩擦圧接している。摩擦圧接後、図５（ｂ）に示すように、定着金物５１とネジ節鉄筋５２とが接合面がテーパ状の凹形状の接合部５３で一体となった補強部材５０となる。
【００２６】
（引張試験）
実施例１、２、３および比較例１、２の各補強部材１０〜５０について、接合部を挟んで引張試験を実施した。引張試験は接合後の補強部材の定着金物を固定し、もう一方は鉄筋を固定して、鉄筋の軸方向の引張力のみがかかるようにした。表２に実施例１、２、３および比較例１、２における補強部材の定着金物の接合面の形状、接合面積の増加率、補強部材の接合部を挟んで引張試験を行ったときの引張最大荷重（補強部材の引張最大荷重）および破断部位を示す。また、鉄筋単体で引張試験したときに得られた引張最大荷重も併記した。
【００２７】
【表２】

【００２８】
実施例１〜３では、接合面積の増加率は１．０２〜２．９２倍となっている。引張試験の結果、実施例１〜３の補強部材の破断部位は全て鉄筋となった。何れの補強部材でも、その引張最大荷重が、鉄筋単体での引張最大荷重と全く同じ値を示したことからも破断部位が鉄筋であることがわかる。一方、比較例１、２の接合面積の増加率は、それぞれ１．００倍および３．４２倍であり、引張試験の結果、補強部材の破断部位は接合部であった。また、比較例１、２の補強部材の引張最大荷重は、鉄筋単体での引張最大荷重よりも小さかった。
【００２９】
実施例１〜３の補強部材１０、２０、３０は、定着金物１１、２１、３１の接合面にテーパ状または半球状の凹形状１１ｂ、２１ｂ、３１ｂを形成し、鉄筋１２、２２、３２は、軸方向にほぼ垂直な端面１２ｂ、２２ｂ、３２ｂを有している。このような構成からなる定着金物と鉄筋とを摩擦圧接すると、摩擦熱によって、主に、接合部の熱容量の小さい鉄筋が軟化し、鉄筋が定着金物の凹形状に沿って変形するので、摩擦圧接後の接合部の形状は、接合前の定着金物の凹形状に近い形状となって接合が完了する。実施例１〜３では、定着金物１１、２１、３１の接合面に凹形状１１ｂ、２１ｂ、３１ｂを形成し、接合面積の増加率を１．０２〜２．９２倍に増加しているので、接合部の強度が増加し、この結果、引張試験における補強部材の引張最大荷重が鉄筋単体での引張最大荷重と同じ値を示し、鉄筋部で破断したと考えられる。
【００３０】
一方、比較例１の補強部材４０は、定着金物４１の接合面を平面からなる端面４１ｅとし、異形鉄筋４２は、軸方向にほぼ垂直な端面４２ｂを有している。比較例１では、定着金物と鉄筋とが何れも軸方向に垂直な端面同士の接合となるので、摩擦圧接後の接合部の形状は、異形鉄筋４２が定着金物４１にわずかに食込むものの、接合面積の増加率は１．００倍と小さく十分でない。このため接合部の強度が増加せず、補強部材の引張最大荷重は２００ｋＮで、鉄筋単体での引張最大荷重３６０ｋＮよりも小さい値となり、接合部で破断したと考えられる。
【００３１】
また、比較例２の補強部材５０は、定着金物５１の接合面にテーパ状の凹形状５１ｂを形成し、ネジ節鉄筋５２は、軸方向にほぼ垂直な端面５２ｂを有している。このような構成からなる定着金物と鉄筋とを摩擦圧接すると、摩擦熱によって、主に、接合部の熱容量の小さい鉄筋が軟化し、鉄筋が定着金物の凹形状に沿って変形するので、摩擦圧接後の接合部の形状は、接合前の定着金物の凹形状に近い形状となって接合が完了する。比較例２では、定着金物５１の接合面に凹形状５１ｂを形成し、接合面積の増加率を３．４２倍に増加しているが、補強部材の引張最大荷重は３７０ｋＮで、鉄筋単体での引張最大荷重４６０ｋＮよりも小さい値となり、接合部で破断している。接合面積の増加率を３．４２倍に増加したにもかかわらず接合部の強度が増加しなかったのは、接合面積の増加率を大きくしたことで、図５（ａ）に示すように、鉄筋の中心軸Ｃと定着金物の接合面であるテーパ面Ｓとでなす角度θが小さくなりすぎたため、摩擦圧接時に、定着金物の接合面（凹形状５１ｂ）と鉄筋の接合面（端面５２ｂ）とに軸方向の圧着力（接合面を押付ける圧力）が十分伝わらず、接合が不十分となったことが原因と考えられる。
【００３２】
図６は実施例２の補強部材２０と、比較例２の補強部材５０との引張試験における荷重と変位の関係を示す曲線である。実施例２の補強部材２０は、荷重が鉄筋単体での引張最大荷重を示し、変位も約５０ｍｍと十分に得られて鉄筋で破断した。一方、比較例２の補強部材５０は、荷重が鉄筋の降伏荷重とほぼ同じ値である３７０ｋＮのところで接合部から破断し、変位も約１０ｍｍと小さい値であった。
【００３３】
以上、本発明の実施例について説明したが、本発明はこれらの実施例に何ら限定されるものではなく、特許請求の範囲に示された技術的思想の範疇において変更可能なものである。上記実施例においては、定着金物の接合面にテーパ状または半球状の凹形状を形成し、鉄筋は軸方向にほぼ垂直な端面からなる構成として、摩擦圧接後の接合部の接合面の一部をテーパ状または半球状の凹形状とする実施例について説明したが、鉄筋の端面を垂直ではなく、端面の角部を面取りした形状や尖形としてもよい。また、テーパ状の凹形状としては円錐形のほか、三角錐、四角錐としてもよく、半球状の凹形状としては断面形状で弧状や楕円としてもよい。
【００３４】
また、上記実施例においては、定着金物の材質を機械構造用炭素鋼Ｓ４５Ｃとする実施例について説明したが、定着金物の材質はこれに限定されるものではなく、コンクリート建築物の補強部材としての機能を満足すれば、他の機械構造用炭素鋼のほか、鋳鉄材や鋳鋼材、例えば鋳鉄材として球状黒鉛鋳鉄ＦＣＤ４５０などを用いてもよい。定着金物への凹形状の形成手段としては機械加工が考えられるが、鍛造や鋳造により凹形状を一体的に形成すれば、機械加工を省けるので製作コストを低減できる。
【００３５】
【発明の効果】
以上、詳細に説明のとおり、本発明の鉄筋と定着金物とが摩擦圧接されたコンクリート建築物の補強部材は、補強部材の接合部を挟んで引張試験を行ったときに、鉄筋で破断することから、鉄筋の強度を用いてコンクリート建築物の設計を行うことができ、鉄筋と定着金物とを摩擦圧接した補強部材を用いても設計が煩雑とならない補強部材を得ることができる。
【図面の簡単な説明】
【図１】実施例１の補強部材を示し、（ａ）異形鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接中、（ｃ）摩擦圧接後の各断面図である。
【図２】実施例２の補強部材での、（ａ）ネジ節鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の各断面図である。
【図３】実施例３の補強部材での、（ａ）ネジ節鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の各断面図である。
【図４】比較例１の補強部材での、（ａ）異形鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の各断面図である。
【図５】比較例２の補強部材での、（ａ）ネジ節鉄筋と定着金物との摩擦圧接前、（ｂ）摩擦圧接後の各断面図である。
【図６】実施例２の補強部材と、比較例２の補強部材との引張試験における荷重と変位の関係を示す曲線である。
【図７】異形鉄筋と定着金物とを摩擦圧接している摩擦圧接装置の模式図である。
【図８】特願２００１−２２９６０６号に記載される補強部材を示し、異形鉄筋と定着金物との摩擦圧接後の断面図である。
【図９】特開２００１−１２０１２号公報に記載される定着プレートへの異形鉄筋の取り付け構造の側面図である。
【図１０】コンクリート構造物の補強部材を配設した模式断面図であり、（ａ）は柱、（ｂ）は梁でのものを示す。
【符号の説明】
１０，２０，３０，４０，５０，８０：補強部材
１１，２１，３１，４１，５１，８１：定着金物
１１ｂ，２１ｂ，３１ｂ，５１ｂ：凹形状
１１ｃ，３１ｃ，４１ｃ，５１ｃ：連通孔
１１ｄ，３１ｄ，４１ｄ，５１ｄ：定着金物の正面
１１ｅ，３１ｅ，４１ｅ，５１ｅ：定着金物の端面
１２，４２，８２，９２：異形鉄筋
１２ａ，４２ａ：山形
２２，３２，５２：ネジ節鉄筋
２２ａ，３２ａ，５２ａ：ネジ山
１２ｂ，２２ｂ，３２ｂ，４２ｂ，５２ｂ：鉄筋の端面
１３，２３，３３，４３，５３：接合部
１４，３４：バリ
７１：機台
７３：油圧シリンダ
７４：電動機
７５：主軸
７６：チャック
７７：取付具
８５，９５：圧接部
９１：定着プレート
９３：雄ネジ部材
９４：ナット
１０１ａ，１０１ｂ：定着金物
１０２ａ：柱主筋
１０２ｂ：梁主筋
１０３：柱
１０４：梁
Ｃ：鉄筋の中心軸
Ｓ：定着金物の接合面であるテーパ面Ｓ
θ：鉄筋の中心軸Ｃと定着金物の接合面であるテーパ面Ｓとでなす角度[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reinforcing member for a concrete building.
[0002]
[Prior art]
FIGS. 10A and 10B are schematic sectional views in which a reinforcing member for a concrete structure (hereinafter, referred to as a “reinforcing member” for abbreviating “a reinforcing member for a concrete structure”) is provided. Conventionally, as shown in FIG. 10, (a) a pillar main bar 102a is provided for a column 103, and (b) a beam main bar 102b is provided for a beam 104. A threaded bar or deformed bar is used for the column main bar 102a and the beam main bar 102b. Fixing hardwares 101a and 101b are provided at the ends of the column main bar 102a and the beam main bar 102b in order to enhance the fixing property to the concrete and the compressive strength and the tensile strength. Are attached respectively.
[0003]
A conventional reinforcing member for attaching a deformed reinforcing bar to a fixing plate using friction welding will be described. FIG. 9 is a side view of a structure for attaching a deformed reinforcing bar to a fixing plate disclosed in JP-A-2001-12012. In FIG. 9, a male screw member 93 made of steel and having a male screw formed on the outer periphery coaxially with the deformed reinforcing bar 92 is joined to the tip of the deformed reinforcing bar 92 by friction welding. The fixing plate 91 is mounted on the male screw member 93 with two nuts 94 screwed into the male screw of the male screw member 93. In addition, 95 is a press contact part. According to Japanese Patent Application Laid-Open No. 2001-12012, the type of the reinforcing bar is not limited to the threaded bar, and a commercially available nut used in a normal mechanical structure can be used for the nut to be screwed to the male screw member. The size is smaller than that of the nut screwed to the threaded bar, so that the cost of the column main bar and beam main bar can be reduced, and the arrangement is advantageous.
[0004]
In view of the problem of the reinforcing member of the concrete building disclosed in Japanese Patent Application Laid-Open No. 2001-12012, the present inventors, for example, fix a disk-shaped fixing member to an end of a deformed reinforcing bar 82 as shown in FIG. Invented a reinforcing member 80 for a concrete building characterized by directly joining metal parts 81 by friction welding, and filed an application in Japanese Patent Application No. 2001-229606.
[0005]
[Problems to be solved by the invention]
However, the reinforcing member of the invention of Japanese Patent Application No. 2001-229606 has a problem in that, when a steel material such as carbon steel for machine structure is used for the fixing metal, if the strength of the material of the reinforcing steel is greater than the strength of the material of the steel material, When a tensile test was carried out with an interposed part, there was a case where the joint was broken. Here, the joining portion refers to a portion formed by a heat-affected portion and a joining surface by friction welding of the fixing hardware and the reinforcing bar. If there is a joint with lower strength than a reinforcing bar in the design of a concrete building, the strength of both the joint and the reinforcing bar must be considered, making the design complicated, and the performance of the high-strength rebar cannot be fully demonstrated. There was a problem.
[0006]
Further, in the above-mentioned reinforcing member, even when the strength of the material of the fixing metal is greater than the strength of the material of the reinforcing bar, if the strength of the joint is inferior to the strength of the material of the reinforcing bar due to the thermal effect at the time of friction welding, the joining portion is also required. When a tensile test was carried out with the steel sheet interposed therebetween, there was a risk of breaking at the joint. For this reason, there has been a problem that the design becomes complicated similarly to the above.
[0007]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a reinforcing member whose design is not complicated even when a reinforcing member in which a reinforcing bar and a fixing metal are friction-welded is used.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, a reinforcing member of a concrete building in which a reinforcing bar and a fixing metal according to the present invention are friction-welded is characterized in that, when a tensile test is performed across a joint, the reinforcing member breaks at the reinforcing bar. . By breaking at the reinforcing bar, the strength of the joint can be regarded as equal to or higher than that of the reinforcing bar, and the design of a concrete building can be performed using the strength of the reinforcing bar, so that the design is simplified. In addition, the reinforcing member of the present invention can be used for a part where more strength is required, and it is also possible to take advantage of the characteristics of a high-strength rebar.
[0009]
Further, in the reinforcing member of the present invention, the area of the joint surface of the joint between the reinforcing bar and the fixing hardware (hereinafter, the area of the joint surface of the joint is abbreviated to “joining area”) is the axial direction of the reinforcing bar. The area is preferably 1.01 to 3.00 times the area of the vertical cross section. With respect to the tensile strength per unit area of the reinforcing bar, the tensile strength per unit area of the joint between the fixing hardware and the reinforcing bar is low, but the bonding area is set to 1.01 times or more of the area of the axial vertical cross section of the reinforcing bar. By increasing the joint area, the tensile strength in the axial direction of the joint can be improved. On the other hand, if the joining area is larger than 3.00 times the area of the reinforcing bar in the axial vertical section, it takes time and effort to prepare the reinforcing bar and the fixing metal before the friction welding, and the joint surface between the central axis of the reinforcing bar and the fixing metal is required. Is too small, the axial crimping force (pressure for pressing the joint surface) on the joint surface between the fixing hardware and the reinforcing bar during friction welding is insufficient, and it is difficult to perform joining successfully during friction welding. A more preferred range is that the area of the joint surface of the joint between the reinforcing bar and the fixing metal is 1.5 to 2.5 times the area of the cross section perpendicular to the axial direction of the reinforcing bar.
[0010]
Further, in the reinforcing member of the present invention, it is preferable that at least a part of the joining surface of the joining portion has a tapered shape or a hemispherical concave shape. For example, when frictional welding is performed between a tapered or hemispherical concave fixing hardware and a reinforcing bar having an end surface that is substantially perpendicular to the axial direction, the softening of the material occurs mainly on the reinforcing bar having a small heat capacity at the joint due to frictional heat. Then, the reinforcing bar is deformed along the concave shape of the fixing hardware, and the shape of the joining portion becomes a shape close to the concave shape of the fixing hardware before joining, and the joining is completed. Since the joining surface of the joining portion has a tapered or hemispherical concave shape, the fixing metal and the reinforcing bar can both increase the joining area as compared with joining of the end surfaces perpendicular to the axial direction, and as a result, The strength of the joint increases.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the invention will be described in detail based on examples. Table 1 shows the types (materials) and tensile strengths of the materials of the fixing hardware and the reinforcing bars subjected to the test. The nominal diameter of the rebar used in the test is D25.
[0012]
[Table 1]

[0013]
(Example 1)
First Embodiment A first embodiment will be described with reference to FIGS. The material is a fixing metal and a reinforcing bar, and are carbon steel S45C for machine structural use and SD490, respectively.
[0014]
FIG. 1 is a cross-sectional view of (a) a reinforcing member before friction welding between a deformed reinforcing bar and a fixing metal, (b) during friction welding, and (c) after a friction welding, and FIG. It is a schematic diagram of the friction welding apparatus which friction-welds metal. In FIG. 1A, a communication hole 11c penetrating from the front surface 11d to the end surface 11e is formed in the fixing hardware 11 at the center of the shaft. Further, a joint surface serving as a joint portion with the deformed reinforcing bar 12 is formed in a tapered concave shape 11b. The deformed reinforcing bar 12 is formed with a chevron 12a, and is cut to a predetermined length at an end face 12b. The end face 12b of the deformed reinforcing bar 12 can be friction-welded while being cut by a saw or the like, and there is no need to manage the unevenness caused by cutting and the perpendicularity of the surface.
[0015]
On the other hand, the friction welding apparatus shown in FIG. 7 includes a machine base 71, a main shaft 75 reciprocating on the machine base 71 by a hydraulic cylinder 73 and driven to rotate by an electric motor 74, and a fixing hardware at an end of the main shaft 75. 11 comprises a chuck 76 for gripping the deformed reinforcing bar 12 and a fixture 77 for gripping and fixing the deformed reinforcing bar 12.
[0016]
The friction welding between the deformed reinforcing bar 12 and the fixing hardware 11 is performed as follows. First, the fixing metal 11 is gripped by the chuck 76, and the end face 12 b of the deformed reinforcing bar 12 is fixed to the fixture 77 by protruding. Next, the electric motor 74 is rotated to transmit the torque to the main shaft 75, and the fixing metal 11 is moved to the deformed reinforcing bar 12 side (the right side in the drawing) by the hydraulic cylinder 73. Then, as shown in FIG. 1B, the fixing metal 11 is brought into contact with the concave shape 11b, which is the joining surface, while rotating the fixing metal 11 with the end face 12b of the deformed reinforcing bar 12, thereby generating frictional heat. In this friction heating step, a friction speed, a friction pressure, and a friction time according to the material of the fixing hardware 11 and the deformed reinforcing bar 12 are appropriately selected. Next, the electric motor 74 is stopped and the main shaft 75 is suddenly stopped by a brake (not shown) to apply an upset pressure. In this upset step, an upset pressure and an upset time are appropriately selected according to the materials of the fixing hardware 11 and the deformed reinforcing bars 12. Thus, as shown in FIG. 1C, the reinforcing member 10 is formed by integrating the fixing hardware 11 and the deformed reinforcing bar 12 at the joint 13 having a tapered concave joint surface.
[0017]
Since the burrs 14 at the time of friction welding come out into the communication holes 11c formed in the fixing hardware 11 by the friction welding, the burrs 14 are visually observed from the front surface 11d of the fixing hardware 11, so that the friction welding is reliably performed. And its reliability can be easily confirmed before it is installed in a concrete building.
[0018]
(Example 2)
2A and 2B are cross-sectional views of (a) a reinforcing member before friction welding between a screw bar and a fixing metal and (b) a reinforcing member after friction welding in Example 2. FIG. The materials are a fixing metal and a reinforcing bar, which are S45C quenched and tempered material for machine structural use and SD685, respectively. In FIG. 2A, the fixing metal 21 has a tapered concave shape 21 b at a joint surface to be joined to the screw bar 22. The threaded bar 22 is formed with a thread 22a, and is cut to a predetermined length at an end face 22b. The end face 22b of the threaded bar 22 can be friction-welded while being cut with a saw or the like, and it is not necessary to manage unevenness and verticality of the surface caused by cutting.
[0019]
In the second embodiment as well, the fixing metal 21 and the screw bar 22 are friction-welded with each other by the friction welding device shown in FIG. After the friction welding, as shown in FIG. 2 (b), the fixing member 21 and the screw-bar rebar 22 become the reinforcing member 20 in which the joint surface is integrated by a concave joint 23 having a tapered concave surface.
[0020]
(Example 3)
3A and 3B are cross-sectional views of (a) a reinforcing member before friction welding between a screw bar and a fixing metal and (b) a reinforcing member after friction welding in Example 3. The materials are a fixing metal and a reinforcing bar, which are S45C quenched and tempered material for machine structural use and SD685, respectively. In FIG. 3A, a communication hole 31c penetrating from the front face 31d to the end face 31e is formed in the fixing hardware 31 at the center of the shaft. Further, a joint surface serving as a joint portion with the threaded bar 32 is formed in a hemispherical concave shape 31b. The threaded bar 32 has a thread 32a and is cut to a predetermined length at an end face 32b. The end face 32b of the threaded bar 32 can be subjected to friction welding while being cut with a saw or the like, and it is not necessary to manage unevenness and verticality of the surface caused by cutting.
[0021]
In the third embodiment as well, the fixing hardware 31 and the screw bar 32 are friction-welded with each other by the friction welding device shown in FIG. After the friction welding, as shown in FIG. 3B, the fixing member 31 and the thread-bar rebar 32 become the reinforcing member 30 in which the joining surface is integrated by a joining portion 33 having a hemispherical concave shape. Further, the burrs 34 at the time of friction pressing come out of the communication holes 31c formed in the fixing hardware 31. By visually checking the burrs 34 from the front 31d direction of the fixing hardware 31, the friction pressing is reliably performed. This shows that its reliability can be confirmed before it is installed in a concrete building.
[0022]
(Comparative Example 1)
4A and 4B are cross-sectional views of (a) a reinforcing member before friction welding between a deformed reinforcing bar and a fixing metal and (b) a reinforcing member after friction welding in Comparative Example 1. FIG. The material is a fixing metal and a reinforcing bar, and are carbon steel S45C for machine structural use and SD490, respectively. In FIG. 4A, a communication hole 41c penetrating from the front surface 41d to the end surface 41e is formed at the center of the shaft of the fixing hardware 41. In addition, a joint surface serving as a joint portion with the deformed reinforcing bar 42 is a flat end surface 41e. The deformed reinforcing bar 42 is formed with a chevron 42a, and is cut to a predetermined length at an end face 42b. The end face 42b of the deformed reinforcing bar 42 can be friction-welded while being cut with a saw or the like, and there is no need to manage the unevenness caused by cutting and the perpendicularity of the face.
[0023]
Also in Comparative Example 1, the fixing metal 41 and the deformed reinforcing bar 42 are friction-welded by the friction welding device shown in FIG. After the friction welding, as shown in FIG. 4B, the fixing member 41 and the deformed reinforcing bar 42 become the reinforcing member 40 integrated at the joining portion 43.
[0024]
(Comparative Example 2)
5A and 5B are cross-sectional views of (a) a reinforcing member before friction welding of a screw bar and a fixing metal and (b) a reinforcing member after friction welding in Comparative Example 2. FIG. The materials are a fixing metal and a reinforcing bar, which are S45C quenched and tempered material for machine structural use and SD685, respectively. In FIG. 5A, a communication hole 51c penetrating from the front surface 51d to the end surface 51e is formed in the fixing hardware 51 at the center of the shaft. Further, a joint surface serving as a joint portion with the screw joint rebar 52 is formed in a tapered concave shape 51b. The threaded bar 52 is formed with a thread 52a, and is cut to a predetermined length at an end face 52b. The end face 52b of the threaded bar 52 can be subjected to friction welding while being cut with a saw or the like, and there is no need to manage the unevenness and verticality of the surface caused by cutting.
[0025]
Also in Comparative Example 2, the fixing metal member 51 and the screw bar 52 are friction-welded by the friction welding device shown in FIG. After the friction welding, as shown in FIG. 5B, a reinforcing member 50 is formed by integrating the fixing hardware 51 and the threaded bar 52 at a joint 53 having a tapered concave joint surface.
[0026]
(Tensile test)
For each of the reinforcing members 10 to 50 of Examples 1, 2, and 3 and Comparative Examples 1 and 2, a tensile test was performed with the joint portion interposed therebetween. In the tensile test, the fixing metal of the reinforcing member after joining was fixed, and the other was fixed with a reinforcing bar so that only the tensile force in the axial direction of the reinforcing bar was applied. Table 2 shows the shape of the joint surface of the fixing metal of the reinforcing member in Examples 1, 2, 3 and Comparative Examples 1 and 2, the increase rate of the joint area, and the tensile force when a tensile test was performed with the joint of the reinforcing member interposed. The maximum load (the maximum tensile load of the reinforcing member) and the fracture site are shown. In addition, the maximum tensile load obtained when a tensile test was performed using only the reinforcing bar was also shown.
[0027]
[Table 2]

[0028]
In Examples 1 to 3, the increase rate of the bonding area is 1.02 to 2.92 times. As a result of the tensile test, all of the fractured portions of the reinforcing members of Examples 1 to 3 were made of reinforcing steel. Since the maximum tensile load of any of the reinforcing members showed the same value as the maximum tensile load of the reinforcing bar alone, it can be seen that the fracture site was the reinforcing bar. On the other hand, the increase rates of the joint areas of Comparative Examples 1 and 2 were 1.00 times and 3.42 times, respectively. As a result of the tensile test, the fractured portion of the reinforcing member was the joint. The maximum tensile load of the reinforcing members of Comparative Examples 1 and 2 was smaller than the maximum tensile load of the reinforcing bar alone.
[0029]
The reinforcing

members

10, 20, and 30 of Examples 1 to 3 have tapered or hemispherical concave shapes 11 b, 21 b, and 31 b formed on the joint surfaces of the fixing

hardware

11, 21, and 31. , End faces 12b, 22b, 32b substantially perpendicular to the axial direction. When the fixing metal having such a configuration and the rebar are friction-welded, frictional heat mainly softens the rebar having a small heat capacity at the joint and deforms the rebar along the concave shape of the fixing metal. The shape of the joining portion after this becomes close to the concave shape of the fixing hardware before joining, and the joining is completed. In Examples 1 to 3, since the concave shapes 11b, 21b, 31b are formed on the joint surfaces of the fixing

hardware

11, 21, 31, and the increase rate of the joint area is increased by 1.02 to 2.92 times. It is considered that the strength of the joint increased, and as a result, the maximum tensile load of the reinforcing member in the tensile test showed the same value as the maximum tensile load of the reinforcing bar alone, and it was considered that the reinforcing bar broke.
[0030]
On the other hand, the reinforcing member 40 of the comparative example 1 has an end surface 41e formed of a flat surface as the joining surface of the fixing hardware 41, and the deformed reinforcing bar 42 has an end surface 42b substantially perpendicular to the axial direction. In Comparative Example 1, since the fixing metal and the reinforcing bar are both joined at the end surfaces perpendicular to the axial direction, the shape of the joint after the friction welding is such that although the deformed reinforcing bar slightly bites into the fixing metal 41, The increase rate of the bonding area is 1.00 times, which is not sufficient. For this reason, the strength of the joint was not increased, and the maximum tensile load of the reinforcing member was 200 kN, which was smaller than the maximum tensile load of the reinforcing bar alone of 360 kN, and it is considered that the joint was broken at the joint.
[0031]
Further, the reinforcing member 50 of Comparative Example 2 has a tapered concave shape 51b formed on the joint surface of the fixing hardware 51, and the screw-bar rebar 52 has an end surface 52b substantially perpendicular to the axial direction. When the fixing metal having such a configuration and the rebar are friction-welded, frictional heat mainly softens the rebar having a small heat capacity at the joint and deforms the rebar along the concave shape of the fixing metal. The shape of the joining portion after this becomes close to the concave shape of the fixing hardware before joining, and the joining is completed. In Comparative Example 2, the concave shape 51b was formed on the joint surface of the fixing hardware 51, and the increase rate of the joint area was increased by 3.42 times. However, the maximum tensile load of the reinforcing member was 370 kN, and The value is smaller than the maximum tensile load of 460 kN, and the joint breaks. The reason that the strength of the joint did not increase despite the increase rate of the joint area being 3.42 times was that the increase rate of the joint area was large, as shown in FIG. Since the angle θ formed between the central axis C of the reinforcing bar and the tapered surface S, which is the bonding surface of the fixing metal, has become too small, the joining surface of the fixing metal (concave shape 51b) and the bonding surface of the reinforcing steel (end surface 52b) during friction welding. It is considered that the reason for this is that the bonding force was insufficiently transmitted in the axial direction (pressure for pressing the bonding surface), resulting in insufficient bonding.
[0032]
FIG. 6 is a curve showing the relationship between the load and the displacement in the tensile test of the reinforcing member 20 of Example 2 and the reinforcing member 50 of Comparative Example 2. In the reinforcing member 20 of Example 2, the load showed the maximum tensile load of the reinforcing bar alone, the displacement was sufficiently obtained as about 50 mm, and the reinforcing member 20 was broken by the reinforcing bar. On the other hand, the reinforcing member 50 of Comparative Example 2 broke from the joint at a load of 370 kN, which is almost the same value as the yield load of the reinforcing bar, and the displacement was a small value of about 10 mm.
[0033]
The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and can be changed within the scope of the technical idea described in the claims. In the above embodiment, a tapered or hemispherical concave shape is formed on the joining surface of the fixing hardware, and the reinforcing bar is constituted by an end surface substantially perpendicular to the axial direction, and a part of the joining surface of the joining portion after the friction welding is performed. Although the embodiment in which the is formed into a tapered or hemispherical concave shape has been described, the end face of the reinforcing bar may not be vertical but may be a shape in which a corner of the end face is chamfered or a pointed shape. In addition to the conical shape, the tapered concave shape may be a triangular pyramid or a quadrangular pyramid, and the semispherical concave shape may be an arc or an ellipse in cross section.
[0034]
Further, in the above-described embodiment, the embodiment in which the material of the fixing hardware is carbon steel S45C for machine structure has been described. However, the material of the fixing hardware is not limited to this, and is used as a reinforcing member of a concrete building. If the function is satisfied, a cast iron material or a cast steel material, for example, a spheroidal graphite cast iron FCD450 or the like may be used as the cast iron material, in addition to other carbon steel for machine structural use. As a means for forming the concave shape on the fixing hardware, machining can be considered. However, if the concave shape is integrally formed by forging or casting, machining can be omitted, so that the manufacturing cost can be reduced.
[0035]
【The invention's effect】
As described above in detail, the reinforcing member of the concrete building in which the reinforcing bar and the fixing metal of the present invention are friction-welded with each other, when the tensile test is performed across the joint of the reinforcing member, the reinforcing member breaks at the reinforcing bar. Therefore, it is possible to design a concrete building using the strength of the reinforcing bar, and it is possible to obtain a reinforcing member whose design is not complicated even when a reinforcing member in which the reinforcing bar is friction-welded to the fixing metal is used.
[Brief description of the drawings]
FIGS. 1A and 1B are cross-sectional views showing a reinforcing member according to a first embodiment, in which (a) before friction welding between a deformed reinforcing bar and a fixing metal, (b) during friction welding, and (c) after friction welding.
2A and 2B are cross-sectional views of a reinforcing member according to a second embodiment, showing (a) before friction welding of a screw bar and a fixing metal, and (b) after friction welding.
3A and 3B are cross-sectional views of a reinforcing member according to a third embodiment, respectively showing (a) before friction welding of a threaded bar and a fixing metal, and (b) after friction welding.
4A and 4B are cross-sectional views of a reinforcing member of Comparative Example 1 showing (a) before friction welding between a deformed reinforcing bar and a fixing metal, and (b) after friction welding.
FIGS. 5A and 5B are cross-sectional views of a reinforcing member of Comparative Example 2 showing (a) before friction welding of a screw bar and a fixing metal, and (b) after friction welding.
FIG. 6 is a curve showing a relationship between a load and a displacement in a tensile test of the reinforcing member of Example 2 and the reinforcing member of Comparative Example 2.
FIG. 7 is a schematic view of a friction welding apparatus that frictionally welds a deformed reinforcing bar and a fixing hardware.
FIG. 8 is a cross-sectional view showing a reinforcing member described in Japanese Patent Application No. 2001-229606 after friction welding of a deformed reinforcing bar and a fixing hardware.
FIG. 9 is a side view of a structure for attaching a deformed reinforcing bar to a fixing plate described in JP-A-2001-12012.
FIG. 10 is a schematic cross-sectional view in which a reinforcing member of a concrete structure is provided, in which (a) is a pillar and (b) is a beam.
[Explanation of symbols]
10, 20, 30, 40, 50, 80: reinforcing

members

11, 21, 31, 41, 51, 81: fixing

hardware

11b, 21b, 31b, 51b:

concave shapes

11c, 31c, 41c, 51c: communication holes 11d. 31d, 41d, 51d:

Front surfaces

11e, 31e, 41e, 51e of fixing hardware: End surfaces 12, 42, 82, 92: deformed reinforcing

bars

12a, 42a:

chevron

22, 32, 52: threaded reinforcing

bars

22a, 32a, 52a:

Threads

12b, 22b, 32b, 42b, 52b: End faces 13, 23, 33, 43, 53 of rebar: Joints 14, 34: Burrs 71: Machine base 73: Hydraulic cylinder 74: Electric motor 75: Spindle 76: Chuck 77: Fixtures 85, 95: Pressure contact portion 91: Fixing plate 93: Male screw member 94: Nuts 101a, 101b: Fixing hardware 102a: Main pillar 102b: Main beam 103: Column 104: Beam C: center axis rebar S: a joint surface of the fixing hardware tapered surface S
θ: Angle formed between the central axis C of the reinforcing bar and the tapered surface S that is the joining surface of the fixing hardware.

Claims

In a reinforcing member of a concrete building in which a reinforcing bar and a fixing metal are friction-welded, when a tensile test is performed across a joint of the reinforcing member, the reinforcing member of the concrete building is broken by the reinforcing bar. .

2. The concrete building according to claim 1, wherein an area of a joint surface of a joint between the reinforcing bar and the fixing metal is 1.03 to 3.00 times an area of an axial vertical cross section of the reinforcing bar. 3. Reinforcement members.

The reinforcing member for a concrete building according to claim 1 or 2, wherein at least a part of a joint surface of the joint portion has a tapered or hemispherical concave shape.