JP4830472B2 - Reinforced structure of reinforced concrete beam with opening, reinforcement method, beam structure - Google Patents
Reinforced structure of reinforced concrete beam with opening, reinforcement method, beam structure Download PDFInfo
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Description
本発明は、開口を有する鉄筋コンクリート梁の補強構造及び補強方法に関する。 The present invention relates to a reinforcing structure and a reinforcing method for a reinforced concrete beam having an opening.
鉄筋コンクリート造の建物を構築する際に、設備配管等を設置するため、鉄筋コンクリート梁を貫通するように開口を設けることがある。しかし、鉄筋コンクリート梁に開口を設けると、開口周辺のコンクリートに局所的な応力が作用し、鉄筋コンクリート梁の強度が低下してしまうため、鉄筋コンクリート梁に開口を設ける際には、開口の径は一般には梁せいの１／３以下と制限されている。このため、梁部材に大開口を設ける必要がある、設備機器を集中管理するオフィスビルなどには、鉄筋コンクリート構造を用いることは難しかった。 When constructing a reinforced concrete building, an opening may be provided to penetrate the reinforced concrete beam in order to install equipment piping and the like. However, when an opening is provided in a reinforced concrete beam, local stress acts on the concrete around the opening, reducing the strength of the reinforced concrete beam. It is limited to 1/3 or less of the beam. For this reason, it is difficult to use a reinforced concrete structure in an office building or the like that centrally manages equipment and equipment that requires a large opening in the beam member.
そこで、鉄筋コンクリート梁の強度を確保しつつ、開口を設ける方法として、例えば特許文献１には、鉄筋コンクリート梁を貫通するように鋼管を設け、この鋼管の両端付近にリング状の鉄板を固着し、このリング状の鉄板にせん断補強筋を固着した鉄筋コンクリート梁の開口補強構造が記載されている。
しかしながら、この開口補強構造を用いて大きな径を有する開口を設けようとすると、施工の際には、リング状の鉄板が障害となるため、梁主筋の配筋作業に手間がかかってしまう。また、リング状の鉄板を避けて配筋の設計をしなければならず、例えば梁主筋を２段配筋できないなど、設計の自由度が損なわれる。また、リング状の鉄板を設けるので、鋼材の使用量が増え、経済性が損なわれる。 However, if an opening having a large diameter is provided using this opening reinforcing structure, the ring-shaped iron plate becomes an obstacle during the construction, and it takes time to arrange the beam main bars. In addition, it is necessary to design the bar arrangement avoiding the ring-shaped iron plate. For example, the beam main bar cannot be arranged in two stages, and the degree of design freedom is impaired. Moreover, since a ring-shaped iron plate is provided, the amount of steel used is increased and the economy is impaired.
本発明は上記の問題に鑑みてなされたものであり、その目的は大きな開口を有する鉄筋コンクリート梁であっても、その開口部の補強を良好な作業性でかつ低コストで行うことが可能な補強構造及び補強方法を提供することである。 The present invention has been made in view of the above problems, and the purpose thereof is reinforcement that can reinforce the opening portion with good workability and low cost even for a reinforced concrete beam having a large opening. It is to provide a structure and a reinforcing method.
本発明の鉄筋コンクリート梁の開口補強構造は、前記開口の内側に嵌挿された鋼管と、
前記鉄筋コンクリート梁の梁主筋を囲むように配されると共に、前記鋼管の外周面に接合されたせん断補強筋とを備えることを特徴とする。また、 前記開口の径が鉄筋コンクリート梁の梁せいの１／３以上、かつ、梁せいより、前記鉄筋コンクリート梁の上下のかぶり厚と、せん断補強筋の径と、主筋の径との計を減じた値以下であってもよい。また、前記せん断補強筋は長方形に成形され、その一辺を前記鋼管に溶接接合されてもよい。
The opening reinforcing structure for a reinforced concrete beam according to the present invention includes a steel pipe fitted inside the opening,
A shear reinforcement bar is provided so as to surround a beam main bar of the reinforced concrete beam, and is joined to an outer peripheral surface of the steel pipe. Further, the diameter of the opening is 1/3 or more of the beam of the reinforced concrete beam, and the total of the upper and lower cover thicknesses of the reinforced concrete beam, the diameter of the shear reinforcing bar, and the diameter of the main bar is reduced from the beam. It may be below the value. The shear reinforcing bar may be formed in a rectangular shape, and one side thereof may be welded to the steel pipe.
また、本発明は、開口が設けられた鉄筋コンクリート梁を補強する方法であって、前記開口の内側に鋼管を嵌挿し、せん断補強筋を、前記鉄筋コンクリート梁の梁主筋を囲むように配すると共に、前記鋼管の外周面に接合することを特徴とする開口補強方法も含むものとする。さらに、本発明は、この補強方法により補強された鉄筋コンクリート梁を含む梁構造を含むものとする。 Further, the present invention is a method of reinforcing a reinforced concrete beam provided with an opening, and a steel pipe is fitted inside the opening, and a shear reinforcing bar is arranged so as to surround the beam main bar of the reinforced concrete beam, also included opening reinforcement method characterized by junction to the outer peripheral surface of the steel pipe. Furthermore, this invention shall include the beam structure containing the reinforced concrete beam reinforced by this reinforcement method.
以上の鉄筋コンクリート梁の開口補強構造によれば、鉄筋コンクリート梁に径が鉄筋コンクリート梁の梁せいの１／３以上の大開口を設けても、開口の無い鉄筋コンクリート梁と同等の強度を持たせることができる。さらに、従来の開口補強構造に比べて、コンパクトであるため、鉄筋の配筋が密にならず、また、鋼材の使用量を削減できる。 According to the above reinforced concrete beam opening reinforcement structure, even if the reinforced concrete beam has a large opening having a diameter of 1/3 or more of the beam of the reinforced concrete beam, it can have the same strength as the reinforced concrete beam having no opening. . Furthermore, since it is more compact than the conventional opening reinforcing structure, the reinforcing bars are not densely arranged, and the amount of steel used can be reduced.
本発明の開口補強構造によれば、鉄筋コンクリート梁に開口を設ける際に、設計の自由度を向上し、配筋作業の際の手間を削減できる。また、鋼材の使用量を減らすことができるため、コストを削減できる。さらに、鉄筋コンクリート梁に強度を損なわずに、径が梁せいの１／３以上の大開口を設けることができるため、設備を集中管理するオフィスビルなどを鉄筋コンクリート造で経済的に施工できる。 According to the opening reinforcing structure of the present invention, when an opening is provided in a reinforced concrete beam, the degree of freedom in design can be improved, and labor for bar arrangement work can be reduced. Moreover, since the usage-amount of steel materials can be reduced, cost can be reduced. Furthermore, since a large opening having a diameter of 1/3 or more than that of the beam can be provided without damaging the strength of the reinforced concrete beam, an office building or the like that centrally manages facilities can be economically constructed with reinforced concrete.
以下、本発明の開口補強構造の一実施形態について図面に基づき説明する。
図１（Ａ）は、本実施形態の補強構造１０が適用された、鉄筋コンクリート梁１５の長手方向の鉛直断面図であり、同図（Ｂ）は、（Ａ）におけるＡ−Ａ’断面の鉛直断面図である。また、図２は、補強構造１０を示す斜視図である。鉄筋コンクリート梁１５はその幅方向を貫通する開口１２を有しており、この開口１２を利用して設備配管等が行われる。
図１に示すように、鉄筋コンクリート梁１５は、梁主筋１４と、梁主筋１４を囲むように配設されたせん断補強筋１３とを備えている。また、開口１２には鋼管１１が嵌挿されている。せん断補強筋１３の開口１２に対応する部分は、開口１２の上下で長方形の枠状に形成され、上側のせん断補強筋１３の下辺及び下側のせん断補強筋１３の上辺は、夫々、鋼管１１の外周面に溶接されることで、図２に示すような補強構造１０が構成されている。
Hereinafter, an embodiment of the opening reinforcing structure of the present invention will be described with reference to the drawings.
FIG. 1A is a vertical cross-sectional view in the longitudinal direction of a reinforced concrete beam 15 to which the reinforcing structure 10 of the present embodiment is applied, and FIG. 1B is a vertical cross-sectional view taken along the line AA ′ in FIG. It is sectional drawing. FIG. 2 is a perspective view showing the reinforcing structure 10. The reinforced concrete beam 15 has an opening 12 penetrating in the width direction, and equipment piping or the like is performed using the opening 12.
As shown in FIG. 1, the reinforced concrete beam 15 includes a beam main bar 14 and a shear reinforcement bar 13 disposed so as to surround the beam main bar 14. A steel pipe 11 is inserted into the opening 12. The portion of the shear reinforcement bar 13 corresponding to the opening 12 is formed in a rectangular frame shape above and below the opening 12, and the lower side of the upper shear reinforcement bar 13 and the upper side of the lower shear reinforcement bar 13 are respectively steel pipes 11. A reinforcing structure 10 as shown in FIG.
一般に、鉄筋コンクリート梁に開口を設けると、内部荷重の流れが変化し、開口の周辺の内部応力が局所的に高くなる。このため、開口の周辺より破壊を生じてしまい、鉄筋コンクリート梁の強度が低下してしまう。かかる理由により、鉄筋コンクリート梁には大開口を設けることができず、鉄筋コンクリート梁に開口を設ける場合には、開口の径が梁せいの１／３以下となるように制限されていた。 Generally, when an opening is provided in a reinforced concrete beam, the flow of internal load changes, and the internal stress around the opening locally increases. For this reason, destruction will arise from the circumference | surroundings of opening, and the intensity | strength of a reinforced concrete beam will fall. For this reason, a large opening cannot be provided in a reinforced concrete beam. When an opening is provided in a reinforced concrete beam, the diameter of the opening is limited to 1/3 or less of the beam.
これに対して、本実施形態の開口補強構造１０によれば、開口１２の内側に鋼管１１が嵌挿されているため、無開口の場合に鉄筋コンクリート梁の開口１２に相当する部分のコンクリート部材が負担する圧縮荷重を鋼管１１が負担する。これにより、開口１２を設けることによる応力分布の変化を抑えることができるため、開口１２の周辺のコンクリートに局所的に大きな圧縮応力が作用することを抑止できる。また、せん断補強筋１３は鋼管１１に堅く溶接されているため、上下のせん断補強筋１３に作用する応力がお互いに伝達され、上下のせん断補強筋１３が一体となり、せん断力に抵抗する。さらに、開口１２の周辺のコンクリート部材に亀裂が入っても、せん断補強筋１３によりコンクリート部材が欠落することを防止する。これにより、開口１２を設けることによる鉄筋コンクリート梁１５の強度の低下を抑えることができ、鉄筋コンクリート梁１５に、鉄筋コンクリート梁１５の梁せいの１／３以上、かつ、梁せいより、鉄筋コンクリート梁１５の上下のかぶり厚と、せん断補強筋１３の径と、梁主筋１４の径との合計を減じた値以下の径の開口１２を設けることが可能になる。 On the other hand, according to the opening reinforcing structure 10 of the present embodiment, since the steel pipe 11 is fitted inside the opening 12, the portion of the concrete member corresponding to the opening 12 of the reinforced concrete beam in the case of no opening is provided. The steel pipe 11 bears the compressive load to be borne. Thereby, since the change of the stress distribution by providing the opening 12 can be suppressed, it can suppress that a big compressive stress acts on the concrete around the opening 12 locally. Further, since the shear reinforcement bars 13 are firmly welded to the steel pipe 11, stresses acting on the upper and lower shear reinforcement bars 13 are transmitted to each other, and the upper and lower shear reinforcement bars 13 are united to resist the shearing force. Furthermore, even if the concrete member around the opening 12 is cracked, the shear reinforcing bar 13 prevents the concrete member from being lost. As a result, it is possible to suppress a decrease in strength of the reinforced concrete beam 15 due to the provision of the opening 12. It is possible to provide the opening 12 having a diameter equal to or smaller than the sum of the cover thickness, the diameter of the shear reinforcing bar 13 and the diameter of the beam main bar 14.
ここで、鉄筋コンクリート梁１５に開口補強構造１０を設けることで、開口１２を設けることによる鉄筋コンクリート梁１５の強度の低下を抑止できることを、有限要素法を用いた数値解析により確認したので、以下説明する。
本検討では、試験体として一般的な鉄筋コンクリート梁の１／２の縮小モデルを用いた。なお、実物大の試験体を用いて解析を行った場合に比べて、せん断強度等は１／４倍になる。試験体は、断面形状：３００×４２５ｍｍ（実物大では６００×８５０ｍｍ）、内法スパン：１７００ｍｍ（実物大では３４００ｍｍ）、開口径：２３６ｍｍ（実物大では４７２ｍｍ）（梁せいの１／１．８）、鋼管の厚さ：１６ｍｍ（実物大では３２ｍｍ）、鋼管の降伏応力：３３０ＭＰａ（鋼種ＳＭ４９０に相当）、梁主筋：３−Ｄ２５、梁主筋降伏応力：５４０ＭＰａ（鋼種ＳＤ４９０に相当）、せん断補強筋：Ｄ６、せん断補強筋降伏応力：３２５ＭＰａ（鋼種ＳＤ２９５に相当）、コンクリート強度：４２Ｎ／ｍｍ２とした。
Here, it has been confirmed by numerical analysis using the finite element method that the reduction in strength of the reinforced concrete beam 15 due to the provision of the opening 12 can be suppressed by providing the opening reinforcing structure 10 in the reinforced concrete beam 15, which will be described below. .
In this study, a reduced model of 1/2 of a general reinforced concrete beam was used as a test body. In addition, compared with the case where it analyzes using a full-size test body, shear strength etc. become 1/4 time. The specimen has a cross-sectional shape of 300 × 425 mm (600 × 850 mm for the actual size), an internal span: 1700 mm (3400 mm for the actual size), an opening diameter: 236 mm (472 mm for the actual size) (1 / 1.8 of the beam length) ), Steel pipe thickness: 16 mm (32 mm in actual size), steel pipe yield stress: 330 MPa (corresponding to steel type SM490), beam main bar: 3-D25, beam main bar yield stress: 540 MPa (corresponding to steel type SD490), shear reinforcement Strain: D6, shear reinforcement yield stress: 325 MPa (corresponding to steel type SD295), concrete strength: 42 N / mm 2 .
本検討では、開口及び開口補強構造を設けていない試験体（試験体ＮＯ．１）、試験体の中央に開口及び開口補強構造を設けた試験体（試験体ＮＯ．２）、試験体の中央に開口を設け、開口補強構造を設けていない試験体（試験体ＮＯ．３）を用い、各試験体に正負交互に変化するせん断荷重を作用させて、荷重−変位曲線及び載荷後の破壊状況について調べた。 In this examination, the test body (test body No. 1) not provided with the opening and the opening reinforcing structure, the test body (test body NO. 2) provided with the opening and the opening reinforcing structure in the center of the test body, the center of the test body Using a test specimen (test specimen No. 3) that is provided with an opening in the opening and no opening reinforcement structure, a shear load that changes alternately between positive and negative is applied to each specimen, and the load-displacement curve and the failure status after loading Investigated about.
図３〜図５は、各試験体の載荷後の破損状況を示す図であり、夫々、試験体ＮＯ．１〜ＮＯ．３を示す。図３と図５を比較するとわかるように、試験体ＮＯ．１は、試験体全体にひび割れが分布しているが試験体ＮＯ．３は、開口１２の周囲にひび割れが分布している。これは、無開口である試験体ＮＯ．１には、局所的な応力の集中が生じないが、開口１２を有する試験体ＮＯ．３では、コンクリート部材の内部応力の流れが変化し、開口１２の周囲の部分に作用する応力が増大しているためである。 3-5 is a figure which shows the damage condition after loading of each test body, respectively, and test body NO. 1-NO. 3 is shown. As can be seen by comparing FIG. 3 and FIG. No. 1 shows cracks distributed throughout the specimen, but specimen no. No. 3 has cracks distributed around the opening 12. This is because the specimen NO. 1 does not cause local stress concentration, but the specimen NO. 3, the flow of internal stress of the concrete member is changed, and the stress acting on the portion around the opening 12 is increased.
しかし、図４に示すように、試験体ＮＯ．２は、開口の周辺にひび割れが集中せず、試験体全体にひび割れが分布している。このことから、開口補強構造を設けることにより応力の流れの変化が抑止され、開口の周囲の応力集中を抑えられることが確認できる。 However, as shown in FIG. In No. 2, cracks do not concentrate around the opening, and cracks are distributed throughout the test specimen. From this, it can be confirmed that by providing the opening reinforcing structure, a change in the flow of stress is suppressed and stress concentration around the opening can be suppressed.
また、図６〜図８は、各試験体の荷重―変形関係を示すグラフであり、図６〜図８は、夫々、試験体ＮＯ．１〜ＮＯ．３を示す。図６と図８を比較すると、試験体ＮＯ．１の最大せん断力は２９０ｋＮ程度であるが、試験体ＮＯ．３の最大せん断力は１７０ｋＮ程度と、無開口の場合の靭性設計指針に基づき算出したせん断耐力に比べて非常に小さい。このことから、鉄筋コンクリート梁に開口を設けると、開口の周辺より破壊が生じてしまうため、鉄筋コンクリート梁の強度が低下することがわかる。 6 to 8 are graphs showing the load-deformation relationships of the respective test specimens, and FIGS. 1-NO. 3 is shown. Comparing FIG. 6 and FIG. 1 has a maximum shearing force of about 290 kN. The maximum shear force of No. 3 is about 170 kN, which is very small compared to the shear strength calculated based on the toughness design guideline in the case of no opening. From this, it can be seen that, when an opening is provided in a reinforced concrete beam, the strength of the reinforced concrete beam is reduced because breakage occurs from the periphery of the opening.
これに対し、図７に示すように、試験体ＮＯ．２の最大せん断耐力は、試験体ＮＯ．１の最大せん断耐力と略等しく、また、無開口の場合（試験体ＮＯ．１）の靭性設計指針に基づき算出したせん断耐力を超えている。このことから、開口補強構造により開口１２の周囲への応力の集中を抑え、鉄筋コンクリート梁の強度の低下を抑止し、無開口の鉄筋コンクリート梁と同等の強度を確保できることがわかる。
以上説明したように、本検討により、開口１２を設ける際に開口補強構造を設けることで、開口が設けられていない鉄筋コンクリート梁と同程度の強度を持つことが確認された。
On the other hand, as shown in FIG. The maximum shear strength of No. 2 is the test specimen NO. 1 and is substantially equal to the maximum shear strength of 1 and exceeds the shear strength calculated based on the toughness design guideline in the case of no opening (test body No. 1). From this, it can be seen that the opening reinforcement structure can suppress the concentration of stress around the opening 12, suppress the decrease in strength of the reinforced concrete beam, and ensure the same strength as the reinforced concrete beam without opening.
As described above, it has been confirmed by the present study that an opening reinforcing structure is provided when the opening 12 is provided, so that it has the same strength as a reinforced concrete beam having no opening.
さらに、開口１２を有する鉄筋コンクリート梁１５に開口補強構造１０を設けることで、鉄筋コンクリート梁１５の強度の低下を抑止できることを１／２の縮小モデルによる実験により確認したので、以下詳細に説明する。 Furthermore, it has been confirmed by an experiment using a 1/2 reduction model that the strength of the reinforced concrete beam 15 can be suppressed by providing the opening reinforcing structure 10 in the reinforced concrete beam 15 having the opening 12, and will be described in detail below.
図９は、本実験で用いた後述する試験体２０の一例（試験体Ａ）を示す断面図である。
上記説明した開口補強構造を備える鉄筋コンクリート梁を模した試験体Ａと、開口を設けていない鉄筋コンクリート梁を模した試験体Ｂにせん断荷重を加え、最大耐力及び変形性能を比較した。なお、図９に示すように、試験体の両端には、アクチュエータによる加力を行うための加力スタブが一体に成形されている。
試験体２０には、一般的な鉄筋コンクリート梁の１／２の縮小モデルを用いた。試験体２０の諸条件は、断面形状：３００×４２５ｍｍ、内法スパン：１７００ｍｍ、開口１２の径：２２０ｍｍ（梁せいの約１／２）、鋼管１１の厚さ：１６ｍｍ（ＳＭ４９０）、鋼管１１の降伏強度：３６３Ｎ／ｍｍ２、梁主筋１４：３−Ｄ２５（ＳＤ４９０）、せん断補強筋１３（無開口部）３−Ｄ６、１５０ｍｍ間隔（ＳＤ２９０）、コンクリート強度：４８Ｎ／ｍｍ２である。なお、開口周辺のせん断補強筋１３は、せん断補強筋比が無開口部と同等（せん断補強筋比０．２％）になるように配筋している。また、鉄筋の降伏強度は、せん断補強筋１３に用いたＤ６（ＳＤ２９０）は２９５Ｎ／ｍｍ２、梁主筋１４に用いたＤ２５（ＳＤ４９０）は５１９Ｎ／ｍｍ２である。
FIG. 9 is a cross-sectional view showing an example (test body A) of a test body 20 described later used in this experiment.
A shear load was applied to the specimen A simulating a reinforced concrete beam provided with the above-described opening reinforcing structure and a specimen B simulating a reinforced concrete beam not provided with an opening, and the maximum proof stress and deformation performance were compared. In addition, as shown in FIG. 9, the force stub for performing the force by an actuator is integrally shape | molded at the both ends of the test body.
For the test body 20, a reduced model of 1/2 of a general reinforced concrete beam was used. Various conditions of the test body 20 are: cross-sectional shape: 300 × 425 mm, inner span: 1700 mm, diameter of the opening 12: 220 mm (about 1/2 of the beam), steel pipe 11 thickness: 16 mm (SM490), steel pipe 11 yield strength of: 363N / mm 2, the beam main reinforcement 14: 3-D25 (SD490) , shear reinforcement 13 (No opening) 3-D6,150mm interval (SD290), concrete strength: a 48N / mm 2. The shear reinforcement bars 13 around the opening are arranged so that the shear reinforcement ratio is the same as that of the non-opening portion (shear reinforcement ratio 0.2%). Further, the yield strength of the reinforcing bars, D6 (SD290) used for shear reinforcement 13 is 295N / mm 2, D25 (SD490 ) used for beam longitudinal reinforcement 14 is 519N / mm 2.
図１０は、本実験で用いた加力システムを示す図である。本実験では、大野式加力法を用い、同図に示すように、アクチュエータを用いて各試験体２０の両端に形成された加力スタブに正負交互に変形角が１／４００、１／２００、１／１００、１／５０、１／２５［ｒａｄ］に到達するようにせん断荷重を作用させて、荷重―変形関係を調べた。また、鋼管１１に溶接接続されたせん断補強筋１３が有効に作用することを確認するため、図１１に示すように、試験体Ａを作成する際に、鋼管１１の上下に溶接接合されたせん断補強筋１３の４箇所（図中、Ｙ−１〜Ｙ−４）に歪ゲージを貼付し、加力中のせん断補強筋１３のひずみを測定した。 FIG. 10 is a diagram showing the force application system used in this experiment. In this experiment, the Ono-type force method is used, and as shown in the figure, the deformation angles are alternately changed to 1/400 and 1/200 on the force stubs formed at both ends of each test body 20 using an actuator. , 1/100, 1/50, 1/25 [rad] was applied to the shear load, and the load-deformation relationship was examined. Further, in order to confirm that the shear reinforcing bar 13 welded and connected to the steel pipe 11 works effectively, as shown in FIG. Strain gauges were affixed to four locations (Y-1 to Y-4 in the figure) of the reinforcing bar 13, and the strain of the shear reinforcing bar 13 during application was measured.
図１２は、試験体Ａ及び試験体Ｂに作用したせん断荷重と変形角の関係を示すグラフである。また、図１３（Ａ）、（Ｂ）は、夫々、試験体Ａ及び試験体Ｂの変形角が１／１００［ｒａｄ］に到達した時の損傷状況を示す写真である。
図１２に示すように、試験体Ａは変形角が１／５０及び１／１００［ｒａｄ］で、試験体Ｂは変形角が１／１００［ｒａｄ］で載荷荷重が最大となっており、この時の試験体Ａ、Ｂの最大積載荷重は略等しい。これにより、上記説明した開口補強構造を設けた鉄筋コンクリート梁は、無開口の鉄筋コンクリート梁と同等の耐力を有することがわかる。
また、変形角が等しい時の試験体Ａ，Ｂに作用する積載荷重を比較すると、略同等、又は試験体Ａに作用している積載荷重が大きい。これにより、上記説明した開口補強構造を設けた鉄筋コンクリート梁は、無開口の鉄筋コンクリート梁と、同等又はそれ以上の変形性能を有することがわかる。
FIG. 12 is a graph showing the relationship between the shear load acting on the specimen A and the specimen B and the deformation angle. FIGS. 13A and 13B are photographs showing the damage situation when the deformation angles of the test body A and the test body B reach 1/100 [rad], respectively.
As shown in FIG. 12, the test body A has deformation angles of 1/50 and 1/100 [rad], and the test body B has a deformation angle of 1/100 [rad], and the loading load is maximum. The maximum loading loads of the test bodies A and B at that time are substantially equal. Thereby, it turns out that the reinforced concrete beam which provided the opening reinforcement structure demonstrated above has the proof stress equivalent to a reinforced concrete beam without opening.
Further, when comparing the load loads acting on the test bodies A and B when the deformation angles are equal, the load loads acting on the test bodies A are substantially equal or large. Thereby, it turns out that the reinforced concrete beam which provided the opening reinforcement structure demonstrated above has a deformation | transformation performance equal to or more than a reinforced concrete beam without opening.
また、図１４は、変形角が１／４００、１／２００、１／１００、１／５０［ｒａｄ］の時の、せん断補強筋のひずみの大きさを示す図である。同図に示すように、最大耐力を示すせん断力が作用している状態である変形角が１／１００［ｒａｄ］の場合には、Ｙ―３及びＹ−４のせん断補強筋が降伏ひずみ（１５２９μ）に達している。このことから、鋼管１１の上下に溶接接続されたせん断補強筋１３が一体となり、上下のせん断補強筋１３に作用する応力がお互いに伝達され、せん断力に抵抗していることがわかる。
以上、本実験により、径が梁せいの１／３以上の大開口を有する鉄筋コンクリート梁に本実施形態の開口補強構造を設けることにより、開口の無い鉄筋コンクリート梁と同等のせん断耐力及び変形性能を確保されることが確認された。また、本実施形態の開口補強構造では、鋼管の上下に溶接接続されたせん断補強筋が一体となり、せん断力に抵抗していることが確認された。
Moreover, FIG. 14 is a figure which shows the magnitude | size of the distortion | strain of a shear reinforcement when a deformation angle is 1/400, 1/200, 1/100, 1/50 [rad]. As shown in the figure, when the deformation angle, which is the state in which the shear force indicating the maximum proof stress is acting, is 1/100 [rad], the Y-3 and Y-4 shear reinforcements are yield strain ( 1529μ). From this, it can be seen that the shear reinforcement bars 13 welded and connected to the upper and lower sides of the steel pipe 11 are integrated, and the stress acting on the upper and lower shear reinforcement bars 13 is transmitted to each other and resists the shearing force.
As described above, the shear strength and deformation performance equivalent to those of reinforced concrete beams without openings are ensured by providing the opening reinforcing structure of this embodiment for reinforced concrete beams having a large opening of 1/3 or more of the diameter of the beam. It was confirmed that Moreover, in the opening reinforcement structure of this embodiment, it was confirmed that the shear reinforcement bars weld-connected on the upper and lower sides of the steel pipe were integrated and resisted the shearing force.
本実施形態の開口補強構造１０によれば、鉄筋コンクリート梁の強度を低下させることなく、径が梁せいの１／３以上の大開口を設けることができる。また、特許文献１記載の開口補強構造に比べて鋼材の使用量が少ないため、コストを削減することができる。さらに、開口補強構造１０は、従来の開口補強構造に比べてコンパクトであるため、設計の自由度が向上し、また、施工時の配筋作業が容易になる。 According to the opening reinforcing structure 10 of the present embodiment, a large opening having a diameter of 1/3 or more of the beam can be provided without reducing the strength of the reinforced concrete beam. Moreover, since the usage-amount of steel materials is small compared with the opening reinforcement structure of patent document 1, cost can be reduced. Furthermore, since the opening reinforcing structure 10 is more compact than the conventional opening reinforcing structure, the degree of freedom in design is improved, and the reinforcement work during construction is facilitated.
さらに、本発明の開口補強構造によれば、鉄筋コンクリート梁に大開口を設けることができるので、設備の集中管理を行うオフィスビルなどの建物も鉄筋コンクリート造で経済的に施工できる。 Furthermore, according to the opening reinforcing structure of the present invention, since a large opening can be provided in the reinforced concrete beam, a building such as an office building that performs centralized management of facilities can be economically constructed with reinforced concrete.
なお、本実施形態では、開口が円形の場合について説明したが、これに限らず、その他の形状の開口を設ける場合にも、その開口の形状に合わせて鋼管を形成し、鋼管の外周面にせん断補強筋を接続する構成とすればよい。 In the present embodiment, the case where the opening is circular has been described. However, the present invention is not limited to this, and even when an opening having another shape is provided, a steel pipe is formed according to the shape of the opening, and the outer periphery of the steel pipe is formed. What is necessary is just to set it as the structure which connects a shear reinforcement.
また、本実施形態では、鉄筋コンクリート梁のスパン中央に開口を設ける場合について説明したが、これに限らず、開口を例えば鉄筋コンクリート柱との接合端部付近等に開口補強構造を設けてもよい。このような場合にも、本発明の開口補強構造を用いることで、無開口の鉄筋コンクリート梁と同等のせん断耐力を確保できる。 Moreover, although this embodiment demonstrated the case where an opening was provided in the span center of a reinforced concrete beam, it is not restricted to this, For example, you may provide an opening reinforcement structure in the joint edge part vicinity etc. with a reinforced concrete pillar. Even in such a case, by using the opening reinforcing structure of the present invention, it is possible to ensure a shear strength equivalent to that of a non-opening reinforced concrete beam.
さらに、せん断補強筋を長方形状に成形し、その一辺を鋼管の外部に接続する構成としたが、これに限らず、例えばせん断補強筋をコの字型に成形し、その端部を直接鋼管に溶接接続する構成としてもよい。 Furthermore, the shear reinforcement is formed into a rectangular shape and one side of the shear reinforcement is connected to the outside of the steel pipe. However, the present invention is not limited to this. For example, the shear reinforcement is formed into a U-shape and the end is directly connected to the steel pipe. It is good also as a structure weld-connected to.
１０ 開口補強構造
１１ 鋼管
１２ 開口
１３ せん断補強筋
１４ 梁主筋
１５ 鉄筋コンクリート梁
DESCRIPTION OF SYMBOLS 10 Opening reinforcement structure 11 Steel pipe 12 Opening 13 Shear reinforcement 14 Beam main reinforcement 15 Reinforced concrete beam
Claims (5)
前記開口の内側に鋼管が嵌挿され、
前記鉄筋コンクリート梁のせん断補強筋が、前記鉄筋コンクリート梁の梁主筋を囲むように配されると共に、前記鋼管の外周面に接合されていることを特徴とする開口を有する鉄筋コンクリート梁の補強構造。 A structure for reinforcing a reinforced concrete beam having an opening,
A steel pipe is inserted inside the opening,
A reinforcing structure for a reinforced concrete beam having an opening , wherein a shear reinforcing bar of the reinforced concrete beam is arranged so as to surround a beam main bar of the reinforced concrete beam and is joined to an outer peripheral surface of the steel pipe.
かつ、梁せいより、前記鉄筋コンクリート梁の上下のかぶり厚と、せん断補強筋の径と、主筋の径と、の合計を減じた値以下であることを特徴とする請求項１記載の開口を有する鉄筋コンクリート梁の補強構造。 The diameter of the opening is 1/3 or more of the beam of the reinforced concrete beam,
2. The opening according to claim 1, wherein the opening is equal to or less than a value obtained by subtracting the sum of the upper and lower cover thicknesses of the reinforced concrete beam, the diameter of the shear reinforcing bar, and the diameter of the main bar from the beam. Reinforced structure of reinforced concrete beams.
前記開口の内側に鋼管を嵌挿し、
せん断補強筋を、前記鉄筋コンクリート梁の梁主筋を囲むように配すると共に、前記鋼管の外周面に接合することを特徴とする開口を有する鉄筋コンクリート梁の補強方法。 A method of reinforcing a reinforced concrete beam having an opening,
Insert a steel pipe inside the opening,
The shear reinforcement, with disposed so as to surround the beam main reinforcement of the reinforced concrete beam, a method of reinforcing concrete beams having an opening, characterized in that the junction to the outer peripheral surface of the steel pipe.
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