JP4456257B2

JP4456257B2 - Semi-fixed direct foundation and pile foundation structure of steel column

Info

Publication number: JP4456257B2
Application number: JP2000347494A
Authority: JP
Inventors: 正明三村; 一義八幡
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2000-08-09
Filing date: 2000-11-15
Publication date: 2010-04-28
Anticipated expiration: 2020-11-15
Also published as: JP2002121747A

Description

【０００１】
【発明の属する技術分野】
本発明は、建物の鉄骨柱の柱脚を半固定とすることにより、上部の鉄骨架構と下部の基礎構造との最適な組み合わせを追求できる鉄骨柱の半固定直接基礎および杭基礎構造に関する。
【０００２】
【従来の技術】
（１）従来、鉄骨架構における鉄骨柱の柱脚の基礎固定の考え方は、ピンもしくは固定という考え方が支配していた。図１５（Ａ）には、鉄骨架構１の鉄骨柱２の柱脚部２ａがピン３で基礎４に結合されたピン結合例が示され、図１５（Ｂ）には、鉄骨柱２の柱脚部２ａが基礎４に埋設固定された例が示されている。
【０００３】
柱脚ピン支持とは、図１６（Ａ）に示すように、鉄骨柱２の柱脚部２ａをピン３を介して基礎４に埋設の固定支持部５に結合することで、鉄骨柱２の回転が自由に行えるように、設計したものである。この場合、図１６（Ｂ）、（Ｃ）に変形と曲げモーメント分布を示すように、鉄骨柱２の柱頭部の変位および曲げモーメントが大きくなり、鉄骨架構としては不経済なものとなりやすかった。反面、基礎の設計においては、柱脚部２ａの曲げモーメントが無いため、軸力と水平力のみに対して設計すればよく、経済的であった。
【０００４】
柱脚固定とは、図１７（Ａ）に示すように、地盤中６に打設したフーチング７に鉄骨柱２の柱脚部２ａを固定することで、鉄骨柱２の回転を全く許さないように設計したものである。この場合、図１７（Ｂ）、（Ｃ）に変形と曲げモーメント分布を示すように、柱脚部２ａに曲げモーメントが発生し、その分柱頭の曲げモーメントが小さくなり、その水平変位も極端に小さくなる。したがって、この柱脚固定は、鉄骨架構としては経済的になるが、基礎に従来の軸力、水平力の他に曲げモーメントが付加され、その基礎は堅牢に構築する必要があり、不経済なものとなり易かった。
【０００５】
更に別の観点から説明すると、地震等で建物に水平力が作用したとき、図１６（Ｂ）の場合は、ピン３を支点として、鉄骨架構１は簡単に傾斜倒壊するおそれがある。また、図１７（Ｂ）の場合は、柱脚部２ａが基礎４に固定されているので、鉄骨柱２に地震力の全部が直接作用するので、当該鉄骨柱２が折損するおそれがある。
【０００６】
従来の鉄骨柱のピン結合、単純固定の考えに対し、近年、ピン結合と固定との中間に位置する半固定という考え方が見られ始めた。この半固定基礎が本発明の対象である。
【０００７】
本発明が対象とする半固定とは、前述のピン結合と固定という概念の中間の概念である。つまり、柱脚の支持機構における回転の拘束を回転ばねと捉えると、図１６のピン支持機構では、バネ係数０の回転ばねであり、図１７の固定支持では、バネ係数無限大の回転ばねであり、これに対し、半固定とは、前記の中間、つまり有限のバネ係数を持った回転ばねといえる。
【０００８】
したがって、その有限のバネ係数の数値に応じて、柱脚の曲げモーメントは変化し、鉄骨架構と基礎との色々な組み合わせが発生してくる。
【０００９】
すなわち、建築材料コストを計算するに際して、鉄骨架構と基礎との合算した金額の最適値を求めることが望ましい。この場合、従来、ピンと固定の２通りの合算値を比較して決定したものが、半固定という手法が可能になれば、その有限のバネ係数を変化させることにより、本当の最適値が見つけられる。（図１８参照）
【００１０】
また、柱脚の半固定の方法としては、図１９に示すように、基礎４と鉄骨柱２を分離し、その間をアンカーボルト８とベースプレート９で連結し、そのアンカーボルト８の伸びを性状に応じて、バネ係数を決めるというのが、一般的に決められた方法である。しかし、この場合、アンカーボルト８はコンクリートに植設されなければならないことから、基礎４を完成してからでないと鉄骨柱２が立てられず、建設工程のネックとなることが多かった。
【００１１】
他方、建設工程を短縮するために、鉄骨柱を基礎の中に埋め込んだ方法が数多く提案されているが、それらのどの案も柱脚を固定と考えており、半固定としてそのバネ係数を調整できる機構を持ったものは無い。
【００１２】
例えば、特開平９−１５１４６３号公報は、基礎の中に鉄骨を埋め込み、一部をコンクリートに対してアンボンド状態である柱一体型柱脚固定基礎構造であるが、対象が捨てコンクリートの上に立てた柱と、各柱間を連結する地中梁からなる構造である。この基礎構造は柱と地中梁を一体化することで建物の強度を向上するものであるが、地中梁の設置のための広範囲に渡る地盤掘削と、その施工作業が必要となる。
【００１３】
その他に、杭頭部に固定して用いる金物が知られているが、従来の金物は、杭と杭頭鉄筋の接続を狙ったものが多く、鉄骨と杭との接合のための杭頭金物は殆どなく、特開平７−３８１７号公報が僅かに関連するものである。しかし、この従来例は鋼管杭のみに適用可能であり、杭頭切断され、切断面が水平面を必ずしも構成していないＰＨＣ杭（中空の既成コンクリート杭）等には適用できない。
【００１４】
【発明が解決しようとする課題】
従来の柱脚の半固定構造では、施工性の問題、あるいは鉄骨柱のバネ係数調整の困難性の問題、構造の複雑性の問題等改良すべき点が多々あった。
【００１５】
本発明は、前記従来の欠点を改良すべく提案したものであり、捨てコンクリートまたは、杭頭部の上に独立基礎梁を設置する構造であり、かつ、柱間を繋ぐ地中梁を必要としない鉄骨柱の半固定直接基礎および杭基礎構造を提供することを目的とする。
【００１６】
すなわち、本発明は、鉄骨柱の柱脚を半固定にすることにより、上部の鉄骨架構と下部の基礎構造との最適な組み合わせを追求できることを可能とし、併せて、基礎構造を鉄骨梁と無筋コンクリートから構成することにより、鉄筋工事等をなくすると共に、直接基礎にあっては、鉄骨工事を捨てコンクリート工事のすぐ後に開始でき、杭基礎にあっては、捨てコンクリートが無いから掘削底部に露出した杭頭部に直ちに鉄骨工事を開始可能として、工期の短縮を図るものである。
【００１７】
【課題を解決するための手段】
前記の目的を達成するため、本発明に係る鉄骨柱の半固定直接基礎と杭基礎構造は、次のように構成する。
【００１８】
本発明に係る鉄骨柱の半固定直接基礎構造は、地盤掘削部に打設の捨てコンクリートの上部で、当該捨てコンクリートから所定寸法離れた位置に、鉄骨柱の曲げモーメントに抵抗する２本以上の第２基礎鉄骨梁と、この第２基礎鉄骨梁の間を繋ぎ、鉄骨柱を挟む位置における一部で前記掘削部に打設するコンクリートとの間に空隙による梁可撓領域を形成した第１基礎鉄骨梁と、当該第１基礎鉄骨梁の上面に接合される前記鉄骨柱とからなり、前記各基礎鉄骨梁を前記コンクリートに埋設し、前記地盤掘削部における、前記第１基礎鉄骨梁と、前記第２基礎鉄骨梁のそれぞれの配置部位の掘削底部の深さを異にしてあり、前記第２基礎鉄骨梁を仮支持手段で仮支持することで、前記第１基礎鉄骨梁を掘削底部から浮かしてコンクリートを打設することを特徴とする。
【００１９】
本発明に係る鉄骨柱の半固定直接基礎構造は、地盤掘削部に打設された杭の杭頭部に支持金物を介して接続され、鉄骨柱の曲げモーメントに抵抗する２本以上の第２基礎鉄骨梁と、この第２基礎鉄骨梁の間を繋ぎ、鉄骨柱を挟む位置における一部で前記掘削部に打設するコンクリートとの間に空隙による梁可撓領域を形成した第１基礎鉄骨梁と、当該第１基礎鉄骨梁の上面に接合される前記鉄骨柱とからなり、前記各基礎鉄骨梁を前記コンクリートに埋設し、前記地盤掘削部における、前記第１基礎鉄骨梁と、前記第２基礎鉄骨梁のそれぞれの配置部位の掘削底部の深さを異にしてあり、前記第２基礎鉄骨梁を仮支持手段で仮支持することで、前記第１基礎鉄骨梁を掘削底部から浮かしてコンクリートを打設することを特徴とする。
【００２０】
本発明に係る鉄骨柱の半固定直接基礎構造は、地盤掘削部に打設の捨てコンクリートの上部で、当該捨てコンクリートから所定寸法離れた位置に、鉄骨柱の曲げモーメントに抵抗する２本以上の第２基礎鉄骨梁と、この第２基礎鉄骨梁の間を繋ぎ、鉄骨柱を挟む位置における一部で前記掘削部に打設するコンクリートとの間に空隙による梁可撓領域を形成した第１基礎鉄骨梁と、当該第１基礎鉄骨梁の上面に接合される前記鉄骨柱とからなり、前記各基礎鉄骨梁を前記コンクリートに埋設し、第１基礎鉄骨梁の外部の所定範囲にわたって発泡プラスチック等の弾性部材を配置してコンクリートを打設することにより、前記第１基礎鉄骨梁と前記コンクリートとの間に梁可撓領域が形成されてなることを特徴とする。
【００２１】
本発明に係る鉄骨柱の半固定直接基礎構造は、地盤掘削部に打設された杭の杭頭部に支持金物を介して接続され、鉄骨柱の曲げモーメントに抵抗する２本以上の第２基礎鉄骨梁と、この第２基礎鉄骨梁の間を繋ぎ、鉄骨柱を挟む位置における一部で前記掘削部に打設するコンクリートとの間に空隙による梁可撓領域を形成した第１基礎鉄骨梁と、当該第１基礎鉄骨梁の上面に接合される前記鉄骨柱とからなり、前記各基礎鉄骨梁を前記コンクリートに埋設し、第１基礎鉄骨梁の外部の所定範囲にわたって発泡プラスチック等の弾性部材を配置してコンクリートを打設することにより、前記第１基礎鉄骨梁と前記コンクリートとの間に梁可撓領域が形成されてなることを特徴とする。
【００２２】
【作用】
（１）本発明では、鉄骨柱に固着した基礎鉄骨梁を、鉄骨柱脚から伝達される応力に対応して自重と圧縮抵抗のみを期待できる無筋コンクリートに埋設してなる、直接基礎または杭基礎構造としている。そして、鉄骨柱脚部の圧縮軸力は、鉄骨柱のすぐ下の無筋コンクリートに伝達され、コンクリートの圧縮抵抗力を通じて支持地盤や杭に伝達される。また、鉄骨柱脚部の引張軸力に対しては、基礎鉄骨梁より上部のコンクリートと土の自重で抵抗する。したがって、コンクリートに期待されるのは、圧縮抵抗力と自重だけであり、鉄筋が不要である。
【００２３】
（２）前記コンクリートの面積は、算定結果に基づいて必要の面積に設定するが、その面積が十分に確保できない場合には、第１基礎鉄骨梁に直交するように他の鉄骨梁を配置し、この鉄骨梁にベースプレート的役割を果たさせ、そのすぐ下のコンクリートに伝達させる。
【００２４】
（３）無筋コンクリートに埋設される前記第１基礎鉄骨梁の一部を、発泡プラスチック等の弾性部材を介してコンクリートとの間に形成する空隙等による梁可撓領域を設けることにより、第１基礎鉄骨梁がその既知の剛性に応じて曲がることにより、鉄骨柱脚部に半固定の基礎があるかのように挙動させることができる。この場合の基礎鉄骨梁のバネ係数は、前記第１基礎鉄骨梁に設ける空隙等の梁可撓領域の長さを変えることで容易に調整できる。
【００２５】
（４）また本発明の直接基礎構造では、捨てコンクリートのすぐ上に各鉄骨基礎梁の構造を設置できることにより、鉄骨工事が、捨てコンクリート工事のすぐ後に開始できることとなり、工程の短縮ができる。
【００２６】
（５）さらに本発明の杭基礎構造では、各基礎鉄骨梁と杭頭部を結合する支持金物を介して手際よく結合できると共に、前記支持金物に、高さおよび水平調整機能を持たせることにより、その調整機能を利用して、各杭毎にバラツキがある杭頭部の高さと水平面を調整することで、基礎鉄骨梁と杭頭部を容易かつ円滑に結合できる。
【００２７】
【発明の実施の形態】
次にこの発明を図示の実施形態に基づいて詳細に説明する。
【００２８】
図１〜図３は実施形態１を、図４〜図６は実施形態２を示し、図７は実施形態１、２における鉄骨柱の半固定直接基礎の配置例の平面説明図である。また、図８〜図１１は実施形態３、図１２は実施形態４、図１３は実施形態５を示す。図１４（Ａ）、（Ｂ）は鉄骨柱の半固定原理を示し、各実施形態に共通する。
【００２９】
図１〜図３を参照して、実施形態１を説明する。まず、地盤面６ａを平面所定形状で、且つ所定位置深さに掘削して根切り１０を造成する。具体的には根切り１０の平面形状は、平面Ｈ形の基礎鉄骨梁１７の形状に合わせて、Ｈ形状に掘削される。すなわち、基礎鉄骨梁１７は図示のように、適切な寸法を保った位置に平行に配置される２つの第２基礎鉄骨梁１３および、それらの鉄骨梁１３を繋ぐように配置される第１基礎鉄骨梁１２とで平面Ｈ形状に形成される。根切り１０はこれに合わせて、この第１、第２の基礎鉄骨梁１２、１３が孔内壁面と十分余裕間隙を保って配置できるような寸法で、かつ平面略Ｈ形状に掘削されている。
【００３０】
平面が略Ｈ形状の根切り１０の深さは、全体を同じ深さに造成しても構わないが、図示例では、両翼根切り溝１０ａは深く掘削し、中間根切り溝１０ｂは、両翼根切り溝１０ａよりも浅く設けている。このように、中間根切り溝１０ｂを浅く設けるのは、根切り１０に打設する無筋コンクリート１６（後述する）の使用材料を、必要最小限に、かつ可及的に軽減するためである。両翼根切り溝１０ａには、捨てコンクリート１１が所定の厚みに打設される。
【００３１】
一方、根切り１０に収容される基礎鉄骨梁１７はＨ形鋼で構成され、かつ前述のとおり、第１基礎鉄骨梁１２と、第１基礎鉄骨梁１２の両端に当該梁と直角に配置され、かつ両梁の上面フランジと下面フランジ同士を溶接等で固定される第２基礎鉄骨梁１３とで平面略Ｈ形に組んで構成される。また、第１基礎鉄骨梁１２の長さ方向中間部で、上フランジ１２ａの上面には柱脚部２ａの下端が溶接等で固着されている。柱脚部２ａには、添接板（スプライスプレート）１８を介して鉄骨柱２の下端部がボルト１９で接合される。
【００３２】
基礎鉄骨梁１７は、予め掘削した根切り１０に打設した捨てコンクリート１１上に、適切な寸法を保った位置に設置され、後工程で打設する無筋コンクリート１６中に埋設される。また、基礎鉄骨梁１７の第１基礎鉄骨梁１２を長さ方向に所定寸法ごとに複数区画し、中間部を第１領域Ｌ₁、その両外側を第２領域Ｌ₂、その外側を第３領域Ｌ₃として区画する。そして、第１領域Ｌ₁と第３領域Ｌ₃を固定領域とし、その外面に密着して無筋コンクリート１６を充填するのに対して、第２領域Ｌ₂は可撓領域として、梁外面と無筋コンクリート１６との間に梁可撓空隙部を形成する。
【００３３】
第１基礎鉄骨梁１２の第２領域Ｌ₂において、無筋コンクリート１６との間に梁可撓空隙を形成する手段の１例として、図示例では第２領域Ｌ₂において、第１基礎鉄骨梁１２の外面に、スタイロフォーム等の発泡プラスチック等２１を当てがい、かつ外周を被覆シート２１ａで被覆することにより、無筋コンクリート１６が第１基礎鉄骨梁１２の外面に直に廻り込まず、コンクリートとの間に可撓空隙を形成する。なお、無筋コンクリート１６との間に可撓空間を形成する手段は前記発泡プラスチック等２１と被覆シート２１ａ併用以外の手段でも構わない。
【００３４】
また、図示例では、無筋コンクリート１６を打設するに先立ち、前記第１基礎鉄骨梁１２を、中間根切り溝１０ｂの底面２０から若干浮かして支持し（支持手段は後述する）、それにより第１基礎鉄骨梁１２の下面にも無筋コンクリート１６が円滑に回り込みやすいように配設してある。これは柱脚部２ａを介して第１基礎鉄骨梁１２が受ける鉄骨柱２からの大きな鉛直荷重が、地盤である中間根切り溝１０ｂの底面２０に直に伝わらず、所定厚Ｔの底部廻り込みコンクリート１６ａで受けるためである。
【００３５】
図２によって、第１基礎鉄骨梁１２を中間根切り溝１０ｂの底面２０から若干浮かして、コンクリート打設まで仮支持する一例を説明する。両翼根切り溝１０ａの底面２０に打設した捨てコンクリート１１に仮支持機能を有するアンカーボルト２２の下部を植設し、当該アンカーボルト２２の上部を第２基礎鉄骨梁１３の下フランジ１３ａにナットを介して高さ調整して固定することで、第１基礎鉄骨梁１２を中間根切り溝１０ｂの底面２０から若干浮かして支持している。アンカーボルト２２は専らコンクリート打設まで第２基礎鉄骨梁１３を仮支持する役目のみであって、無筋コンクリート１６の打設後は、当該コンクリート中に埋め殺しとする。
【００３６】
第１基礎鉄骨梁１２を前述のようにアンカーボルト２２で仮支持して、無筋コンクリート１６を根切り１０に打設したとき、第１基礎鉄骨梁１２と第２基礎鉄骨梁１３は当該無筋コンクリート１６内に埋設される。無筋コンクリート１６の打設高さは、少なくとも第１基礎鉄骨梁１２の上フランジ１２ａが埋設される程度か、それ以上の適切な厚みＴ₁に打設するとよいが、何れにあっても、無筋コンクリート１６は、鉄骨柱２に作用する上揚力に抗して各基礎鉄骨梁１２、１３を抑えるに足りる重量があり、かつ、各基礎鉄骨梁１２、１３を介して伝わる鉄骨柱２からの圧縮荷重に耐え得る量充填される。さらに、第１基礎鉄骨梁１２の下側には底部廻り込みコンクリート１６ａが十分な量廻り込み充填される。
【００３７】
第１基礎鉄骨梁１２を、中間根切り溝１０ｂの底面２０から若干浮かして支持する手段は、アンカーボルト２２以外の方法でもよく、例えば、第１基礎鉄骨梁１２と中間根切り溝１０ｂの底面２０との間に、コンクリートが十分廻り込める空間ができるように任意形状のスペーサを配置してもよい（但し、図示省略する）。
【００３８】
図４〜図６を参照して、実施形態２を説明する。実施形態２が、実施形態１と異なるのは、柱脚部２ａの下端両側部位において、第１基礎鉄骨梁１２の上フランジ１２ａに第３基礎鉄骨梁１４を、当該第１基礎鉄骨梁１２を溶接等により直角配置していることである。それに対応して、根切り１０の平面形状も実施形態１と若干異なっている。つまり、中間根切り溝１０ｂの中間部に中間部翼状根切り溝１０ｃが掘削されており、この根切り溝１０ｃに第３基礎鉄骨梁１４が配設されている。他の構成は実施形態１と同じである。この実施形態２においては、少なくとも、第３基礎鉄骨梁１４の上フランジ１４ａが埋まる程度に無筋コンクリート１６が打設される。
【００３９】
実施形態１、２に係る半固定直接基礎構造は、図７に示すように、独立基礎として建物の鉄骨柱２の立設位置に所定間隔、所定配置で設置される。図中の符号２３は、地上部において建物の柱間を繋ぐ地上梁を略図的に示している。
【００４０】
次に、図８〜図１１と図１２および図１３を参照して、実施形態３、４および５を説明する。この実施形態３、４、５は半固定杭基礎構造であり、この点が、実施形態１、２の半固定直接基礎構造と異なる。
【００４１】
実施形態１、２の半固定直接基礎構造では、両翼根切り溝１０ａの底部の捨てコンクリート１１にアンカーボルト２２が植設され、アンカーボルト２２を介して、第２基礎鉄骨梁１３が仮支持され、その後無筋コンクリート１６が打設されていた。
【００４２】
これに対して、半固定杭基礎構造である実施形態３、４、５において、図８〜図１１の実施形態３では、第２基礎鉄骨梁１３の下部が支持手段２５（以下、支持金物という）を介して杭２４（鋼管杭またはＰＨＣ杭の何れでもよく、以下ＰＨＣ杭として説明する）の杭頭部２４ａに仮支持されている。同じく、図１２の実施形態４では、第２基礎鉄骨梁１３の下部および第１基礎鉄骨梁１２の下部が支持金物２５を介してＰＨＣ杭２４の杭頭部２４ａに仮支持されている。また、図１３の実施形態５では、第１基礎鉄骨梁１２の下部が支持金物２５を介してＰＨＣ杭２４の杭頭部２４ａに仮支持されている。
【００４３】
図８〜図１１を参照して、実施形態３を詳しく説明する。この実施形態３では、両翼根切り溝１０ａの底面２０にＰＨＣ杭２４の杭頭部２４ａが所定高さ突出しており、この杭頭部２４ａに設けた仮支持用の支持金物２５で、第２基礎鉄骨梁１３が高さおよび水平位置調整自在に仮支持されている。
【００４４】
さらに説明すると、ＰＨＣ杭２４は、鉄骨柱２の立設予定位置（図７に示した位置）に所定間隔、所定配置で多数本打設され、その後、根切り１０によって両翼根切り溝１０ａの底部に杭頭部２４ａを所定高さ突出させる。このとき、地盤の支持層に高低があることなどから、杭頭部２４ａが高止まりとなることがあるので、この場合は、杭頭を切断して高止まりの杭頭部２４ａを所定高さに調整するが、杭頭部２４ａの切断面が水平な平坦面を構成していない場合多い。また、ＰＨＣ杭２４の打設位置のずれ、打設角度の傾きなどにより杭頭部２４ａの水平方向の位置ずれなどが生じることがある。
【００４５】
前記のことから、支持金物２５には、杭頭部２４ａと第２基礎鉄骨梁１３との仮支持機能に加え、当該第２基礎鉄骨梁１３の高さ及び水平位置調整機能を具備させている。
【００４６】
支持金物２５の具体的構成は、第２基礎鉄骨梁１３に高さ調整自在に結合される高さ調整ボルト２６および、杭頭部２４ａを水平調整自在に結合する杭固定ボルト２７を金物本体２８に設けて構成される。さらに説明すると、第２基礎鉄骨梁１３の下フランジ１３ａに上部取付け鋼板２９がボルト接合または溶接されていて、上部取付け鋼板２９の下面に取付けナット３０が溶接されており、取付けナット３０に高さ調整ボルト２６の上部がねじ込み固定されている。
【００４７】
金物本体２８は鋼板を折曲げて構成されており、上部水平部２８ａに開設のボルト挿通孔に高さ調整ボルト２６を挿入し、これに上部水平部２８ａの上下面から調整ナット３１を締結することで、高さ調整ボルト２６を、その高さを調整して金物本体２８に固定できる。
【００４８】
金物本体２８の下部側面には、直角折曲げ部を下向きにしたＬ字形ボルト支持板２８ｂが溶接により固定されていて、前記金物本体２８の下部側面およびＬ字形ボルト支持板２８ｂの水平部と鉛直部に開設したねじ穴に、水平固定ボルト２７ａ、２７ｂ、鉛直固定ボルト２７ｃからなる杭固定ボルト２７が螺合されている。固定ボルトの本数は３本以上でもよい。
【００４９】
前記金物本体２８と高さ調整ボルト２６と杭固定ボルト２７からなる支持金物２５は、図１０（Ｂ）、図１１に示すように、ＰＨＣ杭２４の円周方向の３箇所に等角間隔で配置されていて、３個の金物本体２８の上部は平面３角形の連結フレーム３２で結合されている。
【００５０】
したがって、支持金物２５の杭頭部２４ａへの接続と、第１基礎鉄骨梁１２と第２基礎鉄骨梁１３の組立は、例えば次のように行うとよい。
【００５１】
１）予め打設したＰＨＣ杭２４の杭頭部２４ａに支持金物２５を取付け、支持金物２５の上部取付け鋼板２９に第２基礎鉄骨梁１３の下フランジ１３ａを溶接することにより、両翼根切り溝１０ａの片側の溝底部のＰＨＣ杭２４同士を接続する。このとき、杭頭部２４ａの内外周面と杭頂面が３本の杭固定ボルト２７で仮締めされる。
【００５２】
２）、前記１）と同じ作業を、両翼根切り溝１０ａの他側の溝底部のＰＨＣ杭２４についても行う。
【００５３】
３）両翼の根切り溝１０ａに配置された第２鉄骨梁１３同士を繋ぐように、予め鉄骨柱２を溶接してある第１基礎鉄骨梁１２を配置し、それらボルト接合する。第１基礎鉄骨梁１２の一部はスタローフォームなどの発砲プラスチック２１で覆われており、後で打設される無筋コンクリート１６と接触しないようにされている（実施形態１、２と同じ）。
【００５４】
４）両翼の根切り溝１０ａの杭頭部４ａにおいて、３本の杭固定ボルト２７のうち、各鉛直固定ボルト２７ｃの締付を調整することで、杭上端面の不陸（凹凸）等の切断面が平面を構成していない場合の調整を３点支持で行い、上部取付け鋼板２９の水平を出す。また、水平固定ボルト２７ａ、２７ｂの締付けを相互に調節することで、杭頭部４ａの軸心の水平位置のずれを調整して上部取付け鋼板２９（つまり第２基礎鉄骨梁１３）の平面的位置を確定する。さらに、必要に応じて調整ナット３１を締結して、高さ調整ボルト２６の高さを調整し、第２基礎鉄骨梁１３の左右が水平となるように高さを微調整する。
【００５５】
５）こうして、第１基礎鉄骨梁１２と第２基礎鉄骨梁１３を支持金物２５で仮固定した上、根切り１０に打設する無筋コンクリート１６で鉄骨梁全体を埋める（この工程は実施形態２と同じ）。無筋コンクリート１６を打設した後は、この無筋コンクリート１６を介して鉄骨柱２とＰＨＣ杭２４が結合され、支持金物２５は鉄骨柱２の支持機能は必要でなく、埋め殺しとなる。
【００５６】
なお、実施形態３において、ＰＨＣ杭２４と支持金物２５以外の構成は、実施形態１と同じであるので、これと同一要素には同一符号を付して、重複説明を省略する。
【００５７】
実施形態４、５を簡単に説明する。実施形態４が、実施形態３と異なる点は、ＰＨＣ杭２４が、支持金物２５を介して第２基礎鉄骨梁１３の両端部を支持するように設けられているのに加えて、第１基礎鉄骨梁１２の中間部を、支持金物２５を介して支持するようにＰＨＣ杭２４が設けられていることである。また、実施形態５が、実施形態３と異なる点は、第２基礎鉄骨梁１３が省略されており、第１基礎鉄骨梁１２の両端部と中間部を支持金物２５を介して支持するようにＰＨＣ杭２４が設けられていることである。実施形態４、５において、支持金物２５の構成は実施形態３と同じであるので、これについての重複説明を省略する。
【００５８】
【実施形態の作用】
実施形態１〜５の半固定基礎構造に基づく作用を、以下順に説明する。
【００５９】
［１］従来、鉄筋コンクリート構造または鉄骨鉄筋コンクリート構造でしかなかった、鉄骨柱２の半固定直接基礎構造を、本発明では、建物の鉛直荷重を支える鉄骨柱２から伝達される応力に対して自重と、圧縮抵抗のみを期待できる無筋コンクリート１６からなる基礎構造としている。
【００６０】
［２］無筋コンクリート１６中に埋設された第１基礎鉄骨梁１２の第２領域Ｌ₂を梁可撓領域として、スタイロフォーム等の発泡プラスチック等２１で無筋コンクリート１６との間に空隙を取ることにより、第１基礎鉄骨梁１２がその既知の剛性に応じて曲がることにより、鉄骨柱脚部２ａに半固定の基礎であるかのように挙動させる。
【００６１】
すなわち、図１４（Ａ）に示すように、鉄骨柱２が右に傾くとき、第１基礎鉄骨梁１２は、第１領域Ｌ₁と第３領域Ｌ₃を固定領域として、鉄骨柱２の右の第２領域Ｌ₂が図示鎖線のように下に凸に湾曲し、鉄骨柱２の左の第２領域Ｌ₂が図示鎖線のように上に凸に湾曲し、結果として、前述のとおり、鉄骨柱脚部１６ａは半固定の基礎であるかのように右に傾斜挙動する。
【００６２】
また、図１４（Ｂ）に示すように、鉄骨柱２が左に傾くとき、第１基礎鉄骨梁１２は、第１領域Ｌ₁と第３領域Ｌ₃を固定領域として、鉄骨柱２の左の第２領域Ｌ₂が図示鎖線のように下に凸に湾曲し、鉄骨柱２の右の第２領域Ｌ₂が図示鎖線のように上に凸に湾曲し、結果として、前述のとおり、鉄骨柱脚部１６ａは半固定の基礎であるかのように左に傾斜挙動する。
【００６３】
［３］本発明では、捨てコンクリート１１のすぐ上にこの鉄骨基礎構造を設置できることにより、鉄骨工事が、捨てコンクリート工事のすぐ後に開始できることとなり、工程の短縮ができる。
【００６４】
［４］鉄骨柱２が傾斜することにより柱脚部２ａに作用する曲げモーメントは、第１基礎鉄骨梁１２の先端に接続された第２基礎鉄骨梁１３に伝達され、それらを引き上げる力と、押し下げる力に分解される。引き上げる力に対しては、その鉄骨梁１３より上部の無筋コンクリート１６と土の自重で抵抗し、押し下げる力に対しては、その無筋コンクリート１６の圧縮抵抗力を通じて支持地盤に伝達される。
【００６５】
その圧縮抵抗力による伝達については、４５°の角度（図２、図５に符号イで示す）をもって広がって行くことが公知の事実であり、必要な支持地盤面積が算定される。それにもとづき、図２、図５において、捨てコンクリート１１から第２基礎鉄骨梁１３の高さ寸法、および捨てコンクリート１１の位置での中間根切り溝１０ｂの溝幅の寸法を適切に決めるとよい。
【００６６】
［５］支持地盤の耐力が不足の場合は、第１、第２の基礎鉄骨梁１２、１３の長さで調節することで補強可能であり、また、前述から各鉄骨梁の下面と、支持地盤との距離を調節することでも補強可能である。
【００６７】
［６］鉄骨柱脚部２ａの圧縮軸力は、第１基礎鉄骨梁１２を通じて第２基礎鉄骨梁１３に伝達されるのではなく、前記第１基礎鉄骨梁１２にも直に伝達される。したがって、図１〜図３に示す実施形態１において、鉄骨柱２のすぐ下の底部廻り込みコンクリート１６ａの面積が十分に確保できない場合には、図４〜図６に示す実施形態２のように、鉄骨柱２の下端両横で、第１基礎鉄骨梁１２の上面に当該鉄骨梁１２に直交するように第４基礎鉄骨梁１４を配置したことで、この鉄骨梁１４にベースプレート的役割を果たさせ、鉄骨梁１４のすぐ下のコンクリートの圧縮抵抗力を通じて支持地盤に伝達される用に設けてもよい。
【００６８】
第４基礎鉄骨梁１４の圧縮抵抗力による伝達についても、４５°の角度（図２、図５に符号ロで示す）をもって広がって行くことが公知の事実であり、必要な支持地盤面積が算定される。それにもとづき、図２、図５において、第４基礎鉄骨梁１４から中間根切り溝１０ｂと中間部翼状根切り溝１０ｃの底面２０までの高さ寸法、つまり、底部廻り込みコンクリート１６ａの厚みを適切に決めるとよい。
【００６９】
［７］鉄骨柱脚部２ａの引張軸力に対しては、第１基礎鉄骨梁１２を通じて第２基礎鉄骨梁１３に伝達され、鉄骨梁１２、１３より上部の無筋コンクリート１６と土の自重で抵抗される。
【００７０】
［８］前述のように無筋コンクリート１６に期待されるのは、圧縮抵抗力と自重だけであり、鉄筋が不要である。
【００７１】
［９］実施形態３〜５の半固定杭基礎構造にあっては、既述のように、杭頭部２４ａの支持金物２５は無筋コンクリート１６が打設されるまでの、鉄骨柱２に入ってくる力をＰＨＣ杭２４に伝達する役目を果たしており、軽微な構造で可能である。
【００７２】
［１０］ＰＨＣ杭２４の位置は、地中条件で変化し、正確さがあまり求められない。平面的な位置に関しては、正確さを要求される基礎鉄骨梁とは支持金物２５の上部取付け鋼板２９で溶接接合することとし、傾きとレベル高さに支持金物２５の杭固定ボルト２７と高さ調整ボルト２６で調整することにより、正確な位置が出せるようになっている。
【００７３】
［１１］杭の高止まりの際の杭頭切断においては、切断面が平面を構成していない場合が多いが、支持金物２５は杭固定ボルト２７によるピンポイントで杭頭部と接しているので、切断面への適用性が高い。
【００７４】
【発明の効果】
本発明に係る鉄骨柱の半固定直接基礎および半固定杭基礎構造は、次のような効果を有している。
【００７５】
本発明では、鉄骨柱に固着した基礎鉄骨梁は、鉄骨柱脚部から伝達される応力に対して自重と圧縮抵抗のみを期待できる無筋コンクリートに埋設してなる基礎構造とし、鉄骨柱脚部の圧縮軸力は、鉄骨柱のすぐ下の無筋コンクリートに伝達され、コンクリートの圧縮抵抗力を通じて支持地盤に伝達され、鉄骨柱脚部の引張軸力に対しては、基礎鉄骨梁より上部のコンクリートと土の自重で抵抗される。このように本発明では、コンクリートに期待されるのは、圧縮抵抗力と自重だけであり、鉄筋が不要であるので、半固定基礎の施工性が従来に比べて格段に向上し、材料コスト、施工コストが低減できる。
【００７６】
また、本発明では、捨てコンクリートのすぐ上に鉄骨基礎梁の構造を設置できることにより、鉄骨工事が、捨てコンクリート工事のすぐ後に開始できることとなり、工程の短縮ができる。
【００７７】
さらに、本発明では、無筋コンクリートに埋設される前記基礎鉄骨梁の一部を、発泡プラスチック等を介してコンクリートとの間に形成される空隙等の梁可撓領域を設けることにより、基礎鉄骨梁がその既知の剛性に応じて曲がることにより、鉄骨柱脚部に半固定の基礎があるかのように挙動させることができ、半固定の基礎の挙動原理が簡潔であり、さらに、基礎鉄骨梁のバネ係数は、前記基礎鉄骨梁に設ける空隙等の梁可撓領域の長さを変えることで容易に調整できる。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係る鉄骨柱の半固定直接基礎構造の斜視図である。である。
【図２】（Ａ）は本発明の第１実施形態に係る鉄骨柱の半固定直接基礎構造の縦断面図、（Ｂ）は同（Ａ）のｂ−ｂ断面図である。
【図３】本発明の第１実施形態に係る鉄骨柱の半固定直接基礎構造の横断平面図である。
【図４】本発明の第２実施形態に係る鉄骨柱の半固定直接基礎構造の斜視図である。である。
【図５】（Ａ）は、本発明の第２実施形態に係る鉄骨柱の半固定直接基礎構造の縦断面図、（Ｂ）は同（Ａ）のｃ−ｃ断面図である。
【図６】本発明の第２実施形態に係る鉄骨柱の半固定直接基礎構造の横断平面図である。
【図７】鉄骨柱半固定基礎の配置例の平面説明図である。
【図８】本発明の第３実施形態として示す鉄骨柱の半固定杭基礎構造の斜視図である。
【図９】図８に示す鉄骨柱の半固定杭基礎構造の根切り部での縦断面図である。
【図１０】（Ａ）は、図９に示す支持金物の拡大縦断面図、（Ｂ）は、同図（Ａ）のｄ−ｄ断面図である。
【図１１】図１０（Ａ）のｅ−ｅ断面図である。
【図１２】本発明の第４実施形態として示す鉄骨柱の半固定杭基礎構造の斜視図である。
【図１３】本発明の第５実施形態として示す鉄骨柱の半固定杭基礎構造の斜視図である。
【図１４】（Ａ）、（Ｂ）は、鉄骨柱の右傾斜の場合と、左傾斜の場合の半固定原理を示す説明図である。
【図１５】（Ａ）、（Ｂ）は、従来のピン結合と固定構造の鉄骨架構を示す説明図である。
【図１６】（Ａ）は従来のピン結合構造の拡大図、（Ｂ）、（Ｃ）はピン結合構造における柱脚の変形を示す説明図と、曲げモーメントの分布を示す説明図である。
【図１７】（Ａ）は、従来の固定構造の拡大図、（Ｂ）、（Ｃ）は固定構造における柱脚の変形を示す説明図と、曲げモーメントの分布を示す説明図である。
【図１８】建築材料コストを計算するに際して、鉄骨架構と基礎との合算した金額の最適値を求める場合のグラフの図である。
【図１９】（Ａ）、（Ｂ）は、基礎と鉄骨柱の間をアンカーボルトベースプレートで連結した基礎構造例の側面説明図と平面説明図である。
【符号の説明】
１鉄骨架構
２鉄骨柱
２ａ柱脚部
３ピン
４基礎
５固定支持部
６地盤中
６ａ地盤面
７フーチング
８アンカーボルト
９ベースプレート
１０根切り
１０ａ両翼根切り溝
１０ｂ中間根切り溝
１１捨てコンクリート
１２第１基礎鉄骨梁
１２ａ上フランジ
１３第２基礎鉄骨梁
１４第３基礎鉄骨梁
１６無筋コンクリート
１６ａ底面廻り込みコンクリート
１７基礎鉄骨梁
１８添接板（スプライスプレート）
１９ボルト
２０底面
２１発泡プラスチック等
２１ａ被覆シート
２２アンカーボルト
２３地上梁
２４ＰＨＣ杭（鋼管杭）
２４ａ杭頭部
２５支持金物（支持手段）
２６高さ調整ボルト
２７杭固定ボルト
２７ａ水平固定ボルト
２７ｂ水平固定ボルト
２７ｃ鉛直固定ボルト
２８金物本体
２８ａ上部水平部
２８ｂＬ字形ボルト支持板
２９上部取付け鋼板
３０取付けナット
３１調整ナット
３２連結フレーム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semi-fixed direct foundation and a pile foundation structure of a steel column that can pursue an optimal combination of an upper steel frame and a lower foundation structure by semi-fixing a column base of a steel column of a building.
[0002]
[Prior art]
(1) Conventionally, the idea of fixing a column base of a steel column in a steel frame has been dominated by the concept of a pin or fixing. FIG. 15A shows an example of pin connection in which the column base 2a of the steel column 2 of the steel frame 1 is connected to the foundation 4 with the pin 3, and FIG. 15B shows the column of the steel column 2. An example in which the leg 2a is embedded and fixed to the foundation 4 is shown.
[0003]
As shown in FIG. 16 (A), the column base pin support is formed by connecting the column base 2a of the steel column 2 to the fixed support 5 embedded in the foundation 4 via the pin 3, so that the steel column 2 It is designed so that it can rotate freely. In this case, as shown in FIGS. 16B and 16C, deformation and bending moment distribution, the displacement and bending moment of the column head of the steel column 2 increase, and the steel frame tends to be uneconomical. On the other hand, in the design of the foundation, since there is no bending moment of the column base 2a, it is only economical to design for the axial force and the horizontal force, which is economical.
[0004]
As shown in FIG. 17 (A), the column base is fixed so that the rotation of the steel column 2 is not allowed at all by fixing the column base 2a of the steel column 2 to the footing 7 placed in the ground 6. Is designed. In this case, as shown in FIGS. 17B and 17C, the bending moment distribution is generated in the column base 2a, the bending moment of the column head is reduced, and the horizontal displacement is extremely large. Get smaller. Therefore, this column base fixing is economical as a steel frame, but a bending moment is added to the foundation in addition to the conventional axial force and horizontal force, and it is necessary to construct the foundation firmly, which is uneconomical. It was easy to become a thing.
[0005]
From another point of view, when a horizontal force acts on the building due to an earthquake or the like, in the case of FIG. 16B, the steel frame 1 may be easily tilted with the pin 3 as a fulcrum. In the case of FIG. 17 (B), since the column base 2a is fixed to the foundation 4, all of the seismic force directly acts on the steel column 2, so that the steel column 2 may be broken.
[0006]
In contrast to the conventional idea of pin connection and simple fixation of steel columns, in recent years, the idea of semi-fixation located between pin connection and fixation has begun to be seen. This semi-fixed foundation is the subject of the present invention.
[0007]
The semi-fixation targeted by the present invention is an intermediate concept between the above-described concepts of pin coupling and fixation. That is, if the rotation restraint in the column base support mechanism is regarded as a rotation spring, the pin support mechanism in FIG. 16 is a rotation spring with a spring coefficient of 0, and the fixed support in FIG. 17 is a rotation spring with an infinite spring coefficient. On the other hand, the semi-fixed state can be said to be an intermediate spring, that is, a rotary spring having a finite spring coefficient.
[0008]
Therefore, depending on the numerical value of the finite spring coefficient, the bending moment of the column base changes, and various combinations of the steel frame and the foundation are generated.
[0009]
That is, when calculating the building material cost, it is desirable to obtain the optimum value of the sum of the steel frame and the foundation. In this case, if a method of semi-fixing, which is conventionally determined by comparing the two combined values of the pin and the fixed, becomes possible, the true optimum value can be found by changing the finite spring coefficient. . (See Figure 18)
[0010]
Further, as a method of semi-fixing the column base, as shown in FIG. 19, the foundation 4 and the steel column 2 are separated, and the space between them is connected by an anchor bolt 8 and a base plate 9, and the extension of the anchor bolt 8 is made into a property. In accordance with this, it is a generally determined method to determine the spring coefficient. However, in this case, since the anchor bolt 8 must be planted in the concrete, the steel column 2 cannot be set up until the foundation 4 is completed, which often becomes a bottleneck in the construction process.
[0011]
On the other hand, in order to shorten the construction process, many methods of embedding steel columns in the foundation have been proposed, but all of these plans consider the column base to be fixed, and adjust the spring coefficient as semi-fixed No one has a mechanism that can.
[0012]
For example, Japanese Patent Application Laid-Open No. 9-151463 is a column-integrated column base fixed foundation structure in which a steel frame is embedded in a foundation and a part thereof is unbonded to concrete. It is a structure that consists of open columns and underground beams that connect each column. This foundation structure improves the strength of the building by integrating columns and underground beams, but it requires extensive ground excavation and construction work for the installation of underground beams.
[0013]
In addition, there are known hardware that is fixed to the pile head, but many of the conventional hardware is aimed at connecting the pile and the pile head reinforcement, and the pile head hardware for joining the steel frame and the pile There is almost nothing, and JP-A-7-3817 is slightly related. However, this conventional example can be applied only to steel pipe piles, and cannot be applied to PHC piles (hollow precast concrete piles) that are cut at the pile head and whose cut surfaces do not necessarily constitute a horizontal plane.
[0014]
[Problems to be solved by the invention]
In the conventional semi-fixed structure of the column base, there are many points to be improved such as a problem of workability, a difficulty of adjusting the spring coefficient of the steel column, and a problem of the complexity of the structure.
[0015]
The present invention has been proposed in order to improve the above-mentioned conventional drawbacks, and is a structure in which an independent foundation beam is installed on abandoned concrete or a pile head, and an underground beam connecting between columns is required. It aims to provide a semi-fixed direct foundation and pile foundation structure of steel columns that do not.
[0016]
That is, the present invention makes it possible to pursue an optimal combination of the upper steel frame and the lower foundation structure by semi-fixing the column base of the steel column. By constructing from reinforced concrete, it is possible to eliminate rebar construction, etc., and in the case of direct foundations, the steelwork can be abandoned and started immediately after the concrete work. The construction work can be shortened by making it possible to immediately start steelwork on the exposed pile head.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, the steel column semi-fixed direct foundation and the pile foundation structure according to the present invention are configured as follows.
[0018]
The semi-fixed direct foundation structure of a steel column according to the present invention comprises two or more steel plates that resist the bending moment of a steel column at a predetermined distance from the discarded concrete at the upper part of the discarded concrete cast in the ground excavation part. A first beam flexible region is formed by a gap between the second foundation steel beam and the concrete placed between the second foundation steel beam and the excavation part at a position sandwiching the steel column. Comprising a basic steel beam and the steel column bonded to the upper surface of the first basic steel beam, each of the basic steel beams being embedded in the concrete, and in the ground excavation part, the first basic steel beam, The depth of the excavation bottom of each arrangement site of the second basic steel beam is different, and the first basic steel beam is removed from the excavation bottom by temporarily supporting the second basic steel beam by temporary support means. Floating and placing concrete And wherein the Rukoto.
[0019]
The semi-fixed direct foundation structure of a steel column according to the present invention is connected to a pile head of a pile placed in a ground excavation part via a support metal and resists the bending moment of the steel column. The first foundation steel frame in which a beam flexible region is formed by a gap between the foundation steel beam and the concrete that is connected to the second foundation steel beam and is placed in the excavation part at a position sandwiching the steel column. And the steel column joined to the upper surface of the first foundation steel beam, each foundation steel beam is embedded in the concrete, the first foundation steel beam in the ground excavation part, and the first The depth of the bottom of excavation of each arrangement part of 2 foundation steel beams is different, and the 1st foundation steel beam is floated from the excavation bottom by temporarily supporting the 2nd foundation steel beam by temporary support means. It is characterized by placing concrete.
[0020]
The semi-fixed direct foundation structure of a steel column according to the present invention comprises two or more steel plates that resist the bending moment of a steel column at a predetermined distance from the discarded concrete at the upper part of the discarded concrete cast in the ground excavation part. A first beam flexible region is formed by a gap between the second foundation steel beam and the concrete placed between the second foundation steel beam and the excavation part at a position sandwiching the steel column. It consists of a basic steel beam and the steel column joined to the upper surface of the first basic steel beam. Each of the basic steel beams is embedded in the concrete, and a foamed plastic or the like is formed over a predetermined range outside the first basic steel beam. By arranging the elastic member and placing concrete, a beam flexible region is formed between the first foundation steel beam and the concrete.
[0021]
The semi-fixed direct foundation structure of a steel column according to the present invention is connected to a pile head of a pile placed in a ground excavation part via a support metal and resists the bending moment of the steel column. The first foundation steel frame in which a beam flexible region is formed by a gap between the foundation steel beam and the concrete that is connected to the second foundation steel beam and is placed in the excavation part at a position sandwiching the steel column. And a steel column joined to the upper surface of the first foundation steel beam. Each of the foundation steel beams is embedded in the concrete, and an elastic material such as foamed plastic is formed over a predetermined range outside the first foundation steel beam. A beam flexible region is formed between the first foundation steel beam and the concrete by placing members and placing concrete.
[0022]
[Action]
(1) In the present invention, a direct foundation or pile, in which a foundation steel beam fixed to a steel column is embedded in unreinforced concrete that can expect only its own weight and compression resistance corresponding to the stress transmitted from the steel column base It has a basic structure. The compression axial force of the steel column base is transmitted to the unreinforced concrete immediately below the steel column, and is transmitted to the supporting ground and the pile through the compression resistance of the concrete. Also, the tensile axial force of the steel column base is resisted by the weight of the concrete and soil above the foundation steel beam. Therefore, what is expected of concrete is only compression resistance and its own weight, and no reinforcing bars are required.
[0023]
(2) The area of the concrete is set to the required area based on the calculation result. If the area cannot be secured sufficiently, another steel beam is placed so as to be orthogonal to the first foundation steel beam. The steel beam plays the role of a base plate and is transmitted to the concrete immediately below it.
[0024]
(3) By providing a beam flexible region by a gap formed between a part of the first foundation steel beam embedded in unreinforced concrete and the concrete through an elastic member such as foamed plastic, By bending one foundation steel beam according to its known rigidity, the steel column base can behave as if it has a semi-fixed foundation. In this case, the spring coefficient of the basic steel beam can be easily adjusted by changing the length of a beam flexible region such as a gap provided in the first basic steel beam.
[0025]
(4) Moreover, in the direct foundation structure of this invention, since the structure of each steel foundation beam can be installed immediately on abandoned concrete, steel frame construction can be started immediately after abandoned concrete construction, and a process can be shortened.
[0026]
(5) Furthermore, in the pile foundation structure of the present invention, it is possible to skillfully couple each foundation steel beam and the pile head via a support hardware, and to give the support hardware a height and level adjustment function. Using the adjustment function, the foundation steel beam and the pile head can be easily and smoothly joined by adjusting the height and the horizontal plane of the pile head with variation for each pile.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail based on the illustrated embodiment.
[0028]
1 to 3 show the first embodiment, FIGS. 4 to 6 show the second embodiment, and FIG. 7 is an explanatory plan view of an arrangement example of the semi-fixed direct foundation of the steel column in the first and second embodiments. 8 to 11 show the third embodiment, FIG. 12 shows the fourth embodiment, and FIG. 13 shows the fifth embodiment. FIGS. 14A and 14B show the semi-fixing principle of the steel column, which is common to each embodiment.
[0029]
The first embodiment will be described with reference to FIGS. First, the ground surface 6a is excavated to a predetermined plane depth and a predetermined position depth to form a root cut 10. Specifically, the planar shape of the root cut 10 is excavated into an H shape in accordance with the shape of the plane H-shaped foundation steel beam 17. That is, as shown in the figure, the foundation steel beam 17 is arranged in such a manner that two second foundation steel beams 13 arranged in parallel at positions maintaining appropriate dimensions, and a first foundation arranged so as to connect the steel beam 13. The steel beam 12 is formed into a plane H shape. In accordance with this, the root cutting 10 is excavated in a dimension that allows the first and second foundation steel beams 12 and 13 to be arranged with a sufficient clearance from the inner wall surface of the hole and in a substantially plane H shape. .
[0030]
The depth of the root cutting 10 having a substantially H-shaped plane may be formed to the same depth as a whole, but in the illustrated example, both blade root cutting grooves 10a are deeply excavated, and the intermediate root cutting groove 10b is both blades. It is provided shallower than the root cut groove 10a. The reason why the intermediate root cutting groove 10b is provided shallowly is to reduce the amount of material used for the unreinforced concrete 16 (described later) placed in the root cutting 10 to the minimum necessary. . Abandoned concrete 11 is cast in a predetermined thickness in both blade root cutting grooves 10a.
[0031]
On the other hand, the foundation steel beam 17 accommodated in the root cutting 10 is made of H-shaped steel, and is arranged at right angles to the first foundation steel beam 12 and both ends of the first foundation steel beam 12 as described above. In addition, the upper surface flange and the lower surface flange of both beams are assembled in a substantially plane H shape with the second basic steel beam 13 fixed by welding or the like. Moreover, the lower end of the column base part 2a is fixed to the upper surface of the upper flange 12a by welding or the like at the intermediate portion in the length direction of the first foundation steel beam 12. A lower end portion of the steel column 2 is joined to the column base portion 2 a with a bolt 19 via an attachment plate (splice plate) 18.
[0032]
The foundation steel beam 17 is placed at a position maintaining an appropriate dimension on the discarded concrete 11 placed in the root excavation 10 excavated in advance, and is buried in the unreinforced concrete 16 placed in a subsequent process. Further, the first basic steel beam 12 of the basic steel beam 17 is divided into a plurality of predetermined dimensions in the length direction, and the middle portion is defined as the first region L. ₁ , Both sides of the second region L ₂ , Outside the third region L _Three Partition as And the first region L ₁ And the third region L _Three Is the fixed region and is in close contact with the outer surface to fill the unreinforced concrete 16, while the second region L ₂ Forms a flexible beam gap between the beam outer surface and the unreinforced concrete 16 as a flexible region.
[0033]
2nd field L of the 1st foundation steel beam 12 ₂ As an example of a means for forming a beam flexible gap with the unreinforced concrete 16, the second region L in the illustrated example ₂ In this case, the unreinforced concrete 16 is directly applied to the outer surface of the first basic steel beam 12 by applying foamed plastic 21 such as styrofoam to the outer surface of the first basic steel beam 12 and covering the outer periphery with the covering sheet 21a. A flexible gap is formed between the concrete and the concrete. Note that the means for forming the flexible space between the unreinforced concrete 16 may be a means other than the combined use of the foamed plastic 21 or the like and the covering sheet 21a.
[0034]
In the illustrated example, prior to placing the unreinforced concrete 16, the first basic steel beam 12 is supported by being slightly lifted from the bottom surface 20 of the intermediate root groove 10b (support means will be described later), thereby The unreinforced concrete 16 is also arranged on the lower surface of the first foundation steel beam 12 so that it can easily go around. This is because a large vertical load from the steel column 2 received by the first foundation steel beam 12 via the column base 2a is not directly transmitted to the bottom surface 20 of the intermediate root groove 10b, which is the ground, but around the bottom of the predetermined thickness T. This is for receiving with the concrete 16a.
[0035]
An example in which the first foundation steel beam 12 is slightly lifted from the bottom surface 20 of the intermediate root groove 10b and temporarily supported until the concrete is placed will be described with reference to FIG. The lower part of the anchor bolt 22 having a temporary support function is planted in the discarded concrete 11 placed on the bottom surface 20 of both blade root cutting grooves 10a, and the upper part of the anchor bolt 22 is nuted to the lower flange 13a of the second foundation steel beam 13 The first foundation steel beam 12 is supported by being slightly lifted from the bottom surface 20 of the intermediate root groove 10b by adjusting the height of the first basic steel beam 12 and fixing it. The anchor bolt 22 is only used to temporarily support the second foundation steel beam 13 until the concrete is placed, and after the unreinforced concrete 16 is placed, the anchor bolt 22 is buried in the concrete.
[0036]
When the first foundation steel beam 12 is temporarily supported by the anchor bolts 22 as described above and the unreinforced concrete 16 is driven into the root cut 10, the first foundation steel beam 12 and the second foundation steel beam 13 are not in contact with each other. Embedded in reinforced concrete 16. The placement height of the unreinforced concrete 16 is an appropriate thickness T that is at least enough to embed the upper flange 12a of the first foundation steel beam 12 or more. ₁ However, in any case, the unreinforced concrete 16 has a weight sufficient to restrain the foundation steel beams 12 and 13 against the lifting force acting on the steel column 2 and each foundation. An amount that can withstand the compressive load from the steel column 2 transmitted through the steel beams 12 and 13 is filled. Further, a sufficient amount of wraparound concrete 16a is wound around the lower side of the first foundation steel beam 12.
[0037]
The means for supporting the first foundation steel beam 12 by slightly floating from the bottom surface 20 of the intermediate root groove 10b may be a method other than the anchor bolt 22, for example, the bottom surfaces of the first foundation steel beam 12 and the intermediate root groove 10b. A spacer having an arbitrary shape may be arranged between the two and 20 so that a space in which the concrete can sufficiently surround is formed (however, illustration is omitted).
[0038]
The second embodiment will be described with reference to FIGS. The second embodiment differs from the first embodiment in that the third foundation steel beam 14 is disposed on the upper flange 12a of the first foundation steel beam 12 and the first foundation steel beam 12 is disposed on both sides of the lower end of the column base portion 2a. It is arranged at right angles by welding or the like. Correspondingly, the planar shape of the root cut 10 is slightly different from that of the first embodiment. That is, the intermediate wing-shaped root cutting groove 10c is excavated in the intermediate part of the intermediate root cutting groove 10b, and the third foundation steel beam 14 is disposed in the root cutting groove 10c. Other configurations are the same as those of the first embodiment. In the second embodiment, the unreinforced concrete 16 is placed so that at least the upper flange 14a of the third foundation steel beam 14 is filled.
[0039]
As shown in FIG. 7, the semi-fixed direct foundation structures according to the first and second embodiments are installed at predetermined intervals and at predetermined positions as standing foundations of the steel column 2 of the building as independent foundations. Reference numeral 23 in the figure schematically shows a ground beam that connects the columns of the building in the ground.
[0040]
Next, Embodiments 3, 4 and 5 will be described with reference to FIGS. 8 to 11 and FIGS. 12 and 13. This Embodiment 3, 4, 5 is a semi-fixed pile foundation structure, and this point is different from the semi-fixed direct foundation structure of Embodiments 1 and 2.
[0041]
In the semi-fixed direct foundation structures of the first and second embodiments, anchor bolts 22 are planted in the discarded concrete 11 at the bottom of both blade root cutting grooves 10a, and the second foundation steel beam 13 is temporarily supported via the anchor bolts 22. After that, unreinforced concrete 16 was cast.
[0042]
On the other hand, in Embodiments 3, 4 and 5 which are semi-fixed pile foundation structures, in Embodiment 3 of FIGS. 8 to 11, the lower part of the second foundation steel beam 13 is referred to as support means 25 (hereinafter referred to as support hardware). ) Is temporarily supported by a pile head 24a of a pile 24 (which may be either a steel pipe pile or a PHC pile, which will be described below as a PHC pile). Similarly, in Embodiment 4 of FIG. 12, the lower portion of the second foundation steel beam 13 and the lower portion of the first foundation steel beam 12 are temporarily supported by the pile head 24 a of the PHC pile 24 via the support hardware 25. Moreover, in Embodiment 5 of FIG. 13, the lower part of the 1st foundation steel beam 12 is temporarily supported by the pile head part 24a of the PHC pile 24 via the support hardware 25. FIG.
[0043]
The third embodiment will be described in detail with reference to FIGS. In the third embodiment, a pile head 24a of the PHC pile 24 protrudes to a predetermined height on the bottom surface 20 of both blade root cut grooves 10a, and the second support metal 25 for temporary support provided on the pile head 24a The basic steel beam 13 is temporarily supported so that the height and the horizontal position can be adjusted.
[0044]
More specifically, a plurality of PHC piles 24 are placed at a predetermined standing position (position shown in FIG. 7) of the steel column 2 at predetermined intervals and in a predetermined arrangement. The pile head 24a is protruded to the bottom by a predetermined height. At this time, the pile head 24a may become high due to the height of the support layer of the ground. In this case, the pile head 24a is cut to a predetermined height by cutting the pile head. However, in many cases, the cut surface of the pile head 24a does not constitute a horizontal flat surface. Further, the horizontal displacement of the pile head 24a may occur due to the displacement of the placement position of the PHC pile 24, the inclination of the placement angle, or the like.
[0045]
From the above, the support hardware 25 is provided with a function of adjusting the height and horizontal position of the second foundation steel beam 13 in addition to the temporary support function of the pile head 24 a and the second foundation steel beam 13. .
[0046]
The specific structure of the support hardware 25 includes a height adjusting bolt 26 that is coupled to the second foundation steel beam 13 so that the height can be adjusted, and a pile fixing bolt 27 that couples the pile head 24 a so that the pile head 24 a can be adjusted horizontally. It is provided and configured. More specifically, the upper mounting steel plate 29 is bolted or welded to the lower flange 13 a of the second foundation steel beam 13, and the mounting nut 30 is welded to the lower surface of the upper mounting steel plate 29. The upper part of the adjustment bolt 26 is fixed by screwing.
[0047]
The metal body 28 is formed by bending a steel plate, and the height adjustment bolt 26 is inserted into the bolt insertion hole provided in the upper horizontal portion 28a, and the adjustment nut 31 is fastened to the upper horizontal portion 28a from above and below. Thus, the height adjusting bolt 26 can be fixed to the hardware main body 28 by adjusting the height thereof.
[0048]
An L-shaped bolt support plate 28b with a right-angle bent portion facing downward is fixed to the lower side surface of the hardware main body 28 by welding. The lower side surface of the hardware main body 28 and the horizontal portion of the L-shaped bolt support plate 28b are vertically A pile fixing bolt 27 including horizontal fixing bolts 27a and 27b and a vertical fixing bolt 27c is screwed into a screw hole opened in the section. The number of fixing bolts may be three or more.
[0049]
As shown in FIGS. 10B and 11, the support hardware 25 composed of the hardware body 28, the height adjustment bolt 26 and the pile fixing bolt 27 is equiangularly spaced at three locations in the circumferential direction of the PHC pile 24. The upper parts of the three hardware main bodies 28 are connected to each other by a planar triangular connecting frame 32.
[0050]
Therefore, the connection of the support hardware 25 to the pile head 24a and the assembly of the first foundation steel beam 12 and the second foundation steel beam 13 may be performed as follows, for example.
[0051]
1) By attaching the support metal 25 to the pile head 24a of the PHC pile 24 previously placed and welding the lower flange 13a of the second foundation steel beam 13 to the upper mounting steel plate 29 of the support metal 25, both blade root cut grooves The PHC piles 24 at the groove bottoms on one side of 10a are connected. At this time, the inner and outer peripheral surfaces of the pile head 24 a and the pile top surface are temporarily tightened with the three pile fixing bolts 27.
[0052]
2) The same operation as 1) is performed for the PHC pile 24 at the groove bottom on the other side of the blade root cutting grooves 10a.
[0053]
3) The 1st foundation steel beam 12 which welded the steel column 2 beforehand is arranged so that the 2nd steel beam 13 arranged in root cut groove 10a of both wings may be connected, and these bolts are joined. A part of the first basic steel beam 12 is covered with a foamed plastic 21 such as a stuff foam, so as not to come into contact with unreinforced concrete 16 to be placed later (same as in the first and second embodiments). .
[0054]
4) By adjusting the tightening of the vertical fixing bolts 27c among the three pile fixing bolts 27 in the pile head 4a of the root cut grooves 10a of both wings, Adjustment when the cut surface does not constitute a flat surface is performed with three-point support, and the upper mounting steel plate 29 is leveled. Further, by adjusting the tightening of the horizontal fixing bolts 27a and 27b to each other, the horizontal position shift of the axial center of the pile head 4a is adjusted, and the upper mounting steel plate 29 (that is, the second foundation steel beam 13) is planar. Confirm the position. Further, if necessary, the adjustment nut 31 is fastened to adjust the height of the height adjustment bolt 26 and finely adjust the height so that the left and right sides of the second foundation steel beam 13 are horizontal.
[0055]
5) In this way, the first and second foundation steel beams 12 and 13 are temporarily fixed with the support hardware 25, and then the whole steel beam is filled with the unreinforced concrete 16 placed in the root cutting 10 (this process is an embodiment). 2). After placing the unreinforced concrete 16, the steel column 2 and the PHC pile 24 are coupled through the unreinforced concrete 16, and the support hardware 25 does not need the support function of the steel column 2 and is buried.
[0056]
In addition, in Embodiment 3, since structures other than the PHC pile 24 and the support hardware 25 are the same as Embodiment 1, the same code | symbol is attached | subjected to the same element as this, and duplication description is abbreviate | omitted.
[0057]
Embodiments 4 and 5 will be briefly described. The fourth embodiment is different from the third embodiment in that the PHC pile 24 is provided so as to support both ends of the second foundation steel beam 13 via the support hardware 25, and the first foundation. That is, the PHC pile 24 is provided so as to support the intermediate portion of the steel beam 12 via the support hardware 25. Further, the fifth embodiment is different from the third embodiment in that the second foundation steel beam 13 is omitted and the both ends and the middle portion of the first foundation steel beam 12 are supported via the support hardware 25. The PHC pile 24 is provided. In the fourth and fifth embodiments, the configuration of the support hardware 25 is the same as that of the third embodiment, and thus a duplicate description thereof is omitted.
[0058]
Action of Embodiment
The effect | action based on the semi-fixed foundation structure of Embodiment 1-5 is demonstrated in order below.
[0059]
[1] A semi-fixed direct foundation structure of a steel column 2 that has conventionally only been a reinforced concrete structure or a steel-framed reinforced concrete structure. The foundation structure is made of unreinforced concrete 16 that can be expected only in compression resistance.
[0060]
[2] Second region L of the first foundation steel beam 12 embedded in the unreinforced concrete 16 ₂ As a beam flexible region, the first foundation steel beam 12 is bent according to its known rigidity by taking a gap between the stiff foam and other foamed plastics 21 with the unreinforced concrete 16. Let the part 2a behave as if it is a semi-fixed foundation.
[0061]
That is, as shown in FIG. 14A, when the steel column 2 is tilted to the right, the first foundation steel beam 12 is in the first region L. ₁ And the third region L _Three Is the second region L to the right of the steel column 2 ₂ Is curved downwardly as shown by the chain line in the figure, and the second region L on the left side of the steel column 2 ₂ As shown above, the steel column base 16a bends to the right as if it was a semi-fixed foundation.
[0062]
Further, as shown in FIG. 14B, when the steel column 2 is tilted to the left, the first foundation steel beam 12 is in the first region L. ₁ And the third region L _Three As the fixed region, the second region L on the left of the steel column 2 ₂ Is curved convexly downward like the chain line in the figure, and the second region L on the right side of the steel column 2 ₂ As shown above, the steel column base 16a bends to the left as if it was a semi-fixed foundation.
[0063]
[3] In the present invention, since the steel foundation can be installed immediately above the discarded concrete 11, the steel work can be started immediately after the discarded concrete work, and the process can be shortened.
[0064]
[4] The bending moment acting on the column base 2a due to the inclination of the steel column 2 is transmitted to the second foundation steel beam 13 connected to the tip of the first foundation steel beam 12, and a force for pulling them up, Disassembled into a force to push down. The lifting force is resisted by the weight of the unreinforced concrete 16 and the soil above the steel beam 13, and the pushing force is transmitted to the supporting ground through the compressive resistance force of the unreinforced concrete 16.
[0065]
About the transmission by the compression resistance force, it is a well-known fact that it spreads at an angle of 45 ° (indicated by reference character A in FIGS. 2 and 5), and the necessary supporting ground area is calculated. Based on that, in FIGS. 2 and 5, the height dimension of the second foundation steel beam 13 from the discarded concrete 11 and the dimension of the groove width of the intermediate root cutting groove 10 b at the position of the discarded concrete 11 may be appropriately determined.
[0066]
[5] If the proof strength of the supporting ground is insufficient, it can be reinforced by adjusting the lengths of the first and second foundation steel beams 12 and 13, and the lower surface of each steel beam and the support It can be reinforced by adjusting the distance to the ground.
[0067]
[6] The compression axial force of the steel column base 2a is not directly transmitted to the second foundation steel beam 13 through the first foundation steel beam 12, but is also directly transmitted to the first foundation steel beam 12. Accordingly, in the first embodiment shown in FIGS. 1 to 3, when the area of the bottom surrounding concrete 16a just below the steel column 2 cannot be secured, as in the second embodiment shown in FIGS. The fourth foundation steel beam 14 is arranged on the upper surface of the first foundation steel beam 12 on both sides of the lower end of the steel column 2 so as to be orthogonal to the steel beam 12, thereby playing a role of a base plate on the steel beam 14. In addition, it may be provided for transmission to the supporting ground through the compression resistance of the concrete just below the steel beam 14.
[0068]
It is a known fact that the transmission by the compression resistance force of the fourth foundation steel beam 14 also spreads at an angle of 45 ° (indicated by reference sign B in FIGS. 2 and 5), and the necessary supporting ground area is calculated. Is done. Accordingly, in FIGS. 2 and 5, the height dimension from the fourth foundation steel beam 14 to the bottom surface 20 of the intermediate root groove 10b and the intermediate wing-shaped root groove 10c, that is, the thickness of the bottom surrounding concrete 16a is appropriately set. It is good to decide.
[0069]
[7] The tensile axial force of the steel column base 2a is transmitted to the second foundation steel beam 13 through the first foundation steel beam 12, and the unreinforced concrete 16 above the steel beams 12, 13 and the weight of the soil Resisted by.
[0070]
[8] As described above, the unreinforced concrete 16 is only expected to have compression resistance and its own weight, and does not require a reinforcing bar.
[0071]
[9] In the semi-fixed pile foundation structures of Embodiments 3 to 5, as described above, the support hardware 25 of the pile head 24a is formed on the steel column 2 until the unreinforced concrete 16 is placed. It plays the role of transmitting the incoming force to the PHC pile 24 and is possible with a light structure.
[0072]
[10] The position of the PHC pile 24 changes depending on the underground conditions, and accuracy is not required so much. As for the planar position, the foundation steel beam required to be accurate is welded and joined with the upper mounting steel plate 29 of the support hardware 25, and the pile fixing bolt 27 of the support hardware 25 and the height are inclined and level. By adjusting the adjustment bolt 26, an accurate position can be obtained.
[0073]
[11] In the pile head cutting at the time of the high stop of the pile, there are many cases where the cut surface does not constitute a flat surface, but the support hardware 25 is in contact with the pile head at the pin point by the pile fixing bolt 27. High applicability to cut surfaces.
[0074]
【The invention's effect】
The semi-fixed direct foundation and the semi-fixed pile foundation structure of the steel column according to the present invention have the following effects.
[0075]
In the present invention, the foundation steel beam fixed to the steel column is a foundation structure embedded in unreinforced concrete that can expect only its own weight and compression resistance against the stress transmitted from the steel column base, and the steel column base The compressive axial force is transmitted to the unreinforced concrete just below the steel column and is transmitted to the supporting ground through the compressive resistance force of the concrete, and the tensile axial force of the steel column base is higher than the foundation steel beam. Resisted by the weight of concrete and soil. In this way, in the present invention, what is expected of concrete is only compression resistance and its own weight, and no rebar is required, so the workability of the semi-fixed foundation is significantly improved compared to the conventional, material cost, Construction cost can be reduced.
[0076]
In the present invention, since the structure of the steel foundation beam can be installed immediately above the discarded concrete, the steel work can be started immediately after the discarded concrete work, and the process can be shortened.
[0077]
Furthermore, in the present invention, a portion of the foundation steel beam embedded in the unreinforced concrete is provided with a beam flexible region such as a gap formed between the concrete and the concrete via foamed plastic, thereby providing a foundation steel frame. By bending the beam according to its known stiffness, the steel column base can behave as if it has a semi-fixed foundation, the behavior principle of the semi-fixed foundation is simple, and the foundation steel frame The spring coefficient of the beam can be easily adjusted by changing the length of the beam flexible region such as a gap provided in the foundation steel beam.
[Brief description of the drawings]
FIG. 1 is a perspective view of a semi-fixed direct foundation structure of a steel column according to a first embodiment of the present invention. It is.
2A is a longitudinal sectional view of a semi-fixed direct foundation structure of a steel column according to a first embodiment of the present invention, and FIG. 2B is a bb sectional view of FIG.
FIG. 3 is a cross-sectional plan view of a semi-fixed direct foundation structure of a steel column according to the first embodiment of the present invention.
FIG. 4 is a perspective view of a semi-fixed direct foundation structure for a steel column according to a second embodiment of the present invention. It is.
5A is a longitudinal sectional view of a semi-fixed direct foundation structure of a steel column according to a second embodiment of the present invention, and FIG. 5B is a cc sectional view of FIG. 5A.
FIG. 6 is a cross-sectional plan view of a semi-fixed direct foundation structure of a steel column according to a second embodiment of the present invention.
FIG. 7 is an explanatory plan view of an arrangement example of steel column semi-fixed foundations.
FIG. 8 is a perspective view of a steel column semi-fixed pile foundation structure shown as a third embodiment of the present invention.
9 is a longitudinal sectional view of the steel column shown in FIG. 8 at the root cutting portion of the semi-fixed pile foundation structure. FIG.
10A is an enlarged vertical cross-sectional view of the support hardware shown in FIG. 9, and FIG. 10B is a dd cross-sectional view of FIG.
FIG. 11 is a cross-sectional view taken along the line ee of FIG.
FIG. 12 is a perspective view of a steel column semi-fixed pile foundation structure shown as a fourth embodiment of the present invention.
FIG. 13 is a perspective view of a steel column semi-fixed pile foundation structure shown as a fifth embodiment of the present invention.
FIGS. 14A and 14B are explanatory views showing the semi-fixed principle when the steel column is tilted to the right and when tilted to the left.
FIGS. 15A and 15B are explanatory views showing a conventional steel frame structure having a pin connection and fixing structure. FIGS.
FIGS. 16A and 16B are an enlarged view of a conventional pin coupling structure, and FIGS. 16B and 16C are an explanatory diagram showing deformation of a column base in the pin coupling structure and an explanatory diagram showing a distribution of bending moments.
FIGS. 17A and 17B are an enlarged view of a conventional fixing structure, and FIGS. 17B and 17C are an explanatory view showing deformation of a column base in the fixing structure and an explanatory view showing a distribution of bending moments.
FIG. 18 is a graph in the case of obtaining the optimum value of the sum of the steel frame and the foundation when calculating the building material cost.
FIGS. 19A and 19B are a side explanatory view and a plane explanatory view of an example of a foundation structure in which a foundation and a steel column are connected by an anchor bolt base plate.
[Explanation of symbols]
1 Steel frame
2 Steel columns
2a Column base
3 pins
4 basics
5 fixed support parts
6 In the ground
6a Ground surface
7 Footing
8 Anchor bolt
9 Base plate
10 Root cutting
10a Both wing root cut grooves
10b Intermediate root cut groove
11 Abandoned concrete
12 First foundation steel beam
12a Upper flange
13 Second foundation steel beam
14 Third foundation steel beam
16 Unreinforced concrete
16a Bottom-around concrete
17 Foundation steel beam
18 Splice plate
19 volts
20 Bottom
21 Foamed plastic, etc.
21a Cover sheet
22 Anchor bolt
23 Ground beams
24 PHC pile (steel pipe pile)
24a pile head
25 Support hardware (support means)
26 Height adjustment bolt
27 Pile fixing bolt
27a Horizontal fixing bolt
27b Horizontal fixing bolt
27c Vertical fixing bolt
28 Hardware body
28a Upper horizontal part
28b L-shaped bolt support plate
29 Upper mounting steel plate
30 Mounting nut
31 Adjustment nut
32 Connecting frame

Claims

Two or more second foundation steel beams that resist the bending moment of the steel column at a position that is a predetermined distance away from the discarded concrete at the upper part of the discarded concrete cast in the ground excavation section, and the second foundation steel beam A first foundation steel beam in which a beam flexible region is formed by a gap between the concrete and the concrete to be placed in the excavation part at a position where the steel column is sandwiched between the first foundation steel beam and the upper surface of the first foundation steel beam It consists of the steel columns to be joined, and each foundation steel beam is embedded in the concrete,
In the ground excavation part, the depths of the excavation bottoms of the arrangement portions of the first basic steel beam and the second basic steel beam are different, and the second basic steel beam is temporarily supported by temporary support means. Then, the first foundation steel beam is floated from the bottom of excavation, and concrete is cast, and the semi-fixed direct foundation structure of the steel column is provided .

In order to transmit the compressive axial force of the steel column to the supporting ground through the concrete, the first foundation is connected to the lower part of the steel column or the first foundation steel beam bonded to the steel column and embedded in the concrete. The semi-fixed direct foundation structure for a steel column according to claim 1, wherein the second foundation steel beam is disposed in a direction orthogonal to the steel beam.

Between two or more second foundation steel beams that are connected to the pile heads of piles placed in the ground excavation section via support hardware and resist the bending moment of steel columns, and between these second foundation steel beams connecting a first basic steel beam forming a beam flexible area due to the gap between the concrete of pouring to the digging unit in a part in a position sandwiching the steel column is joined to an upper surface of the first basic steel beam The steel column, and each foundation steel beam embedded in the concrete,
In the ground excavation part, the depths of the excavation bottoms of the arrangement portions of the first basic steel beam and the second basic steel beam are different, and the second basic steel beam is temporarily supported by temporary support means. Then, the first foundation steel beam is floated from the bottom of excavation, and concrete is cast, and the semi-fixed direct foundation structure of the steel column is provided .

The support hardware has a height adjusting bolt that is connected to the first or second foundation steel beam side so that the height is adjustable, and a pile fixing bolt that is connected to the pile head side so that the height and the horizontal position can be adjusted. The steel column semi-fixed pile foundation structure according to claim 3, wherein the metal body has a structure.

By placing an elastic member such as foamed plastic over a predetermined range outside the first foundation steel beam and placing concrete, a beam flexible region is formed between the first foundation steel beam and the concrete. semi-fixed substructure of steel columns according to any one of claims 1 to 4, characterized in that.

Two or more second foundation steel beams that resist the bending moment of the steel column at a position that is a predetermined distance away from the discarded concrete at the upper part of the discarded concrete cast in the ground excavation section, and the second foundation steel beam A first foundation steel beam in which a beam flexible region is formed by a gap between the concrete and the concrete to be placed in the excavation part at a position where the steel column is sandwiched between the first foundation steel beam and the upper surface of the first foundation steel beam It consists of the steel columns to be joined, and each foundation steel beam is embedded in the concrete,
By placing an elastic member such as foamed plastic over a predetermined range outside the first foundation steel beam and placing concrete, a beam flexible region is formed between the first foundation steel beam and the concrete. semi-fixed spread foundation structure of steel columns, characterized by comprising.

In order to transmit the compressive axial force of the steel column to the supporting ground through the concrete, the first foundation is connected to the lower part of the steel column or the first foundation steel beam bonded to the steel column and embedded in the concrete. The semi-fixed direct foundation structure for a steel column according to claim 6, wherein the second foundation steel beam is disposed in a direction orthogonal to the steel beam.

Between two or more second foundation steel beams that are connected to the pile heads of piles placed in the ground excavation section via support hardware and resist the bending moment of steel columns, and between these second foundation steel beams connecting a first basic steel beam forming a beam flexible area due to the gap between the concrete of pouring to the digging unit in a part in a position sandwiching the steel column is joined to an upper surface of the first basic steel beam The steel column, and each foundation steel beam embedded in the concrete,
By placing an elastic member such as foamed plastic over a predetermined range outside the first foundation steel beam and placing concrete, a beam flexible region is formed between the first foundation steel beam and the concrete. semi-fixed spread foundation structure of steel columns, characterized by comprising.

9. The semi-fixed foundation structure according to claim 8, wherein the second foundation steel beam is omitted, and the first foundation steel beam is directly connected to a pile head of a pile placed in a ground excavation part via a support hardware. Semi-fixed pile foundation structure of steel columns, characterized by

The support hardware has a height adjusting bolt that is connected to the first or second foundation steel beam side so that the height is adjustable, and a pile fixing bolt that is connected to the pile head side so that the height and the horizontal position can be adjusted. The semi-fixed pile foundation structure for steel columns according to claim 8 or 9, wherein the metal body has a structure.

The semi-fixed foundation structure for steel columns according to any one of claims 1 to 10, wherein the concrete is unreinforced concrete.