JP4546600B2

JP4546600B2 - Construction method of steel structure large space roof structure and steel structure large space roof structure

Info

Publication number: JP4546600B2
Application number: JP2000033952A
Authority: JP
Inventors: 章梅国; 日出夫岡; 賢一宮崎; 淳道櫛部; 孝寿小川; 俊夫斉藤
Original assignee: Takenaka Corp
Current assignee: Takenaka Corp
Priority date: 2000-02-10
Filing date: 2000-02-10
Publication date: 2010-09-15
Anticipated expiration: 2020-02-10
Also published as: JP2001220819A

Description

【０００１】
【発明の属する技術分野】
この発明は、鉄骨造の大空間屋根構造の構築構法及び鉄骨造の大空間屋根構造の技術分野に属し、更に云えば、屋根鉄骨総重量の軽量化を図ることができ、それに伴い下部躯体の構造部材の軽量化をも図ることができる鉄骨造の大空間屋根構造の構築構法及び鉄骨造の大空間屋根構造に関する。
【０００２】
【従来の技術】
鉄骨造の大空間屋根構造は一般的に、特開平６−２８８００８号公報、特開平８−１４４３７１号公報、特開平１１−１９８９号公報等にも開示されているように、半径方向部材と、同心円状に配置された円周方向部材とから構成されている。
【０００３】
ところで、屋根鉄骨総重量の軽量化を図るには、半径方向部材と円周方向部材にそれぞれ高強度の高張力鋼による部材を配設することにより各部材の断面積を低減させて実施することが有効とされている。
【０００４】
【本発明が解決しようとする課題】
しかしながら、実際、半径方向部材に高張力鋼を配設した場合、通常ほとんどの半径方向部材は圧縮による座屈荷重が支配的となるため、ヤング率や座屈耐力が軟鋼と同等程度しかない高張力鋼を配設する意味はあまりない。一方、円周方向部材、特に最外周に配設される円周方向部材（テンションリング）は引張りのみの荷重が作用するため高張力鋼による部材を配設する利点がある。
そこで、前記テンションリングのみを通常の２倍の強度を有する高張力鋼による部材で実施すると、テンションリングの断面積は略１／２の大きさで略同様に実施できるので、屋根鉄骨総重量の軽量化を図れるように見える。
【０００５】
しかし、構造力学上、テンションリングの軸剛性が１／２となり、屋根構造における半径方向の剛性が急変することより隣り合う一つ内側の円周方向部材の引っ張り応力が増加することとなる。そのため、該円周方向部材は断面積を増加させる必要が生じ、実質上、屋根鉄骨総重量の軽量化を図れているとは云えない。
また、一般に、円周方向部材は、最外周付近に配設される円周方向部材のみに応力が作用しがちで、その内側部分の円周方向部材は有効に活用されていない場合が多く、不経済な設計となっていた。
【０００６】
したがって、本発明の目的は、構造力学的にも支障なく屋根鉄骨総重量の軽量化を図ることができ、それに伴い下部躯体の構造部材の軽量化も図ることができ、その結果、大幅なコストダウンを達成することができる鉄骨造の大空間屋根構造の構築構法及び鉄骨造の大空間屋根構造を提供することにある。
本発明の次の目的は、最外周付近のみならずその内側部分の円周方向部材にも荷重をバランス良く負担させることができる鉄骨造の大空間屋根構造の構築構法及び鉄骨造の大空間屋根構造を提供することにある。
【０００７】
上記従来技術の課題を解決するための手段として、請求項１に記載した発明に係る鉄骨造の大空間屋根構造の構築構法は、
半径方向部材と、同心円状に配置された円周方向部材とで構成される鉄骨造の大空間屋根構造の構築構法において、
前記円周方向部材のうち最外周の円周方向部材は高張力鋼などによるもっとも高強度の鋼種で構成し、その内側の複数の円周方向部材はそれぞれ、半径方向の内方に向かって強度を段階的に小さくした鋼種で構成し、且つ、半径方向の内方に向かって段階的に各円周方向部材の剛性を変化させて、前記各円周方向部材の長期許容応力度に対する軸応力度の比率のばらつきを小さくすることにより、屋根構造の荷重を各円周方向部材にバランス良く負担させる構造に構築することを特徴とする。
【０００８】
請求項２に記載した発明に係る鉄骨造の大空間屋根構造は、
半径方向部材と、同心円状に配置された円周方向部材とで構成される鉄骨造の大空間屋根構造において、
前記円周方向部材のうち最外周の円周方向部材は高張力鋼などによるもっとも高強度の鋼種で構成され、その内側の複数の円周方向部材はそれぞれ、半径方向の内方に向かって強度を段階的に小さくした鋼種で構成され、且つ、半径方向の内方に向かって段階的に各円周方向部材の剛性を変化させて、前記各円周方向部材の長期許容応力度に対する軸応力度の比率のばらつきを小さくすることにより、屋根構造の荷重を各円周方向部材にバランス良く負担させた構造に構築されていることを特徴とする。
【００１０】
図１Ａ、Ｂは、請求項１と請求項２に記載した鉄骨造の大空間屋根構造の構築構法及び鉄骨造の大空間屋根構造を概略的に示している。
請求項１に記載した、半径方向部材２と、同心円状に配置された円周方向部材３とで構成される鉄骨造の大空間屋根構造１の構築構法は、前記円周方向部材３のうち最外周の円周方向部材３ａは高張力鋼などによるもっとも高強度の鋼種（テンションリング）で構成し、その内側の複数の円周方向部材３ｂ、３ｃ、３ｄ、３ｅ…はそれぞれ、半径方向の内方に向かって強度を段階的に小さくした鋼種で構成し、且つ、半径方向の内方に向かって段階的に各円周方向部材の剛性を変化させて、前記各円周方向部材の長期許容応力度に対する軸応力度の比率のばらつき（変化率）を小さくすることにより、屋根構造の荷重を各円周方向部材にバランス良く負担させる構造に構築することを特徴とする（以上、請求項１記載の発明）。
【００１１】
前記構築構法により構築された鉄骨造の大空間屋根構造１は、円周方向部材３のうち最外周の第１の円周方向部材３ａには高張力鋼などによるもっとも高強度の鋼材による部材（テンションリング）が配設され、その一つ内側の第２の円周方向部材３ｂには前記第１の円周方向部材３ａより強度が低い鋼材による部材が配設され、更にその内側の第３以降の円周方向部材３ｃ，３ｄ，３ｅ…には前記第２の円周方向部材３ｂより強度が低い鋼材による部材が配設されている。
【００１２】
更に、前記円周方向部材３をすべて同一強度の鋼種で構成して安定した鉄骨造の大空間屋根構造を設計したモデルと比して、それぞれ対応する円周方向部材３の断面低減率について、前記第１の円周方向部材３ａの断面低減率は略５０％とされ、第２の円周方向部材３ｂの断面低減率は前記第１の円周方向部材３ａの断面低減率と比して減少され、第３以降の円周方向部材３ｃ、３ｄ、３ｅ…の断面低減率は前記第２の円周方向部材３ｂの断面低減率と比して同一若しくは減少されている。
【００１３】
以下、具体的な実施例１〜３に基づき、前記構築構法により構築された鉄骨造の大空間屋根構造１の作用効果を検討する。ちなみに、実施例１は円周方向部材３をすべて同一強度の鋼種で構成して構築したモデルを示し、実施例２は実施例１と比して最外周の円周方向部材のみ２倍の強度を有する鋼種で構成して構築した場合を示し、実施例３は実施例２と比して最外周より内側部分の円周方向部材に、剛性を半径方向の内方に向かって小さくした鋼種で構成して構築した場合の一例を示している。
【００１４】
＜実施例１（原設計）＞
図２Ａ〜Ｃは、直径２００ｍ、高さ３２ｍで、すべての円周方向部材３ａ，３ｂ，３ｃ…が同一強度（鋼材種類：ＳＭ４９０（図５参照））で設計された鉄骨造の大空間屋根構造について示している。荷重は、構造部材で１０７．８ｋＮ／ｍ^３、仕上げ材で７３５Ｎ／ｍ^２とし、自重の合計は約６．４４×１０^４ｋＮとした。この設計で、最外周の円周方向部材（テンションリング）３ａは、外径８００mm、肉厚４５mmで、その他の部材はすべて上下弦材にＨ鋼（３００mm×３００mm×１０mm×１５mm）を配した高さ２ｍのトラスとした。
図２Ａは前記屋根構造の半径方向の断面での各部材軸力をｔｏｎ表示で示し、円周方向部材３ａ、３ｂ、３ｃの軸応力度と、長期許容応力度（ｆｔ）に対する軸応力度の比率（以下適宜「比率」と略称する）を示した。前記軸応力度及び比率は、円周方向部材３ａ，３ｂ，３ｃについてそれぞれ約、１０１Ｎ／ｍｍ^２及び０．４７，６２Ｎ／ｍｍ^２及び０．２９，２０Ｎ／ｍｍ^２及び０．０９である。図２Ｂは同様にモーメントを示した。図２Ｃは変形を示しており、鉛直方向に中心位置で１１．４ｃｍ自重により変形し、半径方向に最外周で４．９ｃｍ変形している。
【００１５】
＜実施例２＞
図３Ａ〜Ｃに示した実施例２は、上記実施例１と比して、最外周の円周方向部材（テンションリング）３ａに前記鋼種：ＳＭ４９０の２倍の強度を有する鋼種：ＨＴ７８０（図５参照）を適用したことのみ相違する。この鋼種：ＨＴ７８０を使用することより部材断面積を略半分の外径８００mm、肉厚２１．８mmとすることができ、よって円周方向部材３ａのみについては軽量化を図ることができる。
【００１６】
図３Ａに示したように、テンションリング３ａの部材の軸応力度（Ｎ／ｍｍ^２）は前記実施例１と比して１７４／１０１＝１．７２倍程度で、比率は前記実施例１の０．４７よりも小さく約０．４０となる。しかし、隣り合う内側の円周方向部材３ｂ，３ｃの軸応力度はそれぞれ、１１１／６２＝１．７９倍程度、４５／２０＝２．２５倍となり、安定した屋根構造とするためには断面積の増加を強いられ、全体として屋根鉄骨総重量の軽量化を図れない。
【００１７】
これは、実施例１に対する剛性の急激な変化により最外周のテンションリング３ａに作用した応力が円周方向部材３ｂ，３ｃに流れてきたことによると考えられる。また、円周方向部材３ｂについては、比率が約０．５１となり、部材の安全性についてもやや欠ける。ちなみに、変形については、図３Ｃに示したように鉛直方向に中心位置で１７．２ｃｍ自重により変形し、半径方向に最外周で８．５ｃｍ変形し、構造力学的に許容範囲内であり問題ない。
【００１８】
＜実施例３＞
図４Ａ〜Ｃに示した実施例３は、請求項３に記載した鉄骨造の大空間屋根構造の一例を示しており、上記実施例２と比して、最外周の円周方向部材３ａより内側の円周方向部材３ｂ，３ｃ…に、図５に示した数種類の異なる強度を有する鋼材を使用していることのみ相違する。具体的には、第１の円周方向部材３ａにＨＴ７８０、第２の円周方向部材３ｂにＳＡ４４０、第３の円周方向部材３ｃにＳＭ５２０、第４以降の円周方向部材にＳＭ４９０と、最外周から半径方向の内方に向かって鋼材の種類を低強度のものに変化させるとともに、実施例１の円周方向部材と対応する円周方向部材３ａ，３ｂ，３ｃ，３ｄ…の断面低減率はそれぞれ、５０％、４７％、４７％、０％としている。ここに、安定した鉄骨造の大空間屋根構造とするべく、長期許容引張応力度（ｆｔ）に対する作用応力度の比率を０．５以下にすることを条件とする。
【００１９】
その結果、上記実施例１と比して、前記比率は、０．４７に対して約０．４２とほとんど変わらない。しかし、円周方向部材３ｂ、３ｃではそれぞれ０．２９に対して約０．４４、０．０９に対して約０．２６と大きくなるとともに、半径方向の内方に向かって変化率（ばらつき）が小さくなっており、部材の高強度化と内側部分の円周方向部材を有効に活用することができ、屋根鉄骨総重量を上記実施例１（原設計）に対し約１１％低減させることができた。また、円周方向部材の剛性を徐々に変化させることにより急激に応力が変化する円周方向部材もなく、最外周付近のみならずその内側部分の円周方向部材にも荷重をバランス良く負担させることができた。ちなみに、変形については、図４Ｃに示したように鉛直方向に中心位置で１８．６ｃｍ自重により変形し、半径方向に最外周で８．９ｃｍ変形し、構造力学的に許容範囲内であり問題ない。
【００２０】
以上の結果、大規模な構造や特殊な構造などテンションリングに大きな力が作用する場合には、さらに大きな低減効果を得ることができることも容易に予測される。
なお、上記実施例３では、第４以降の円周方向部材は全て同一強度の鋼材（ＳＭ４９０）を配設して鉄骨造の大空間屋根構造を構築しているがこれに限定されず、更に段階的に剛性を小さくした鋼材による部材を配設して実施しても良い（請求項２記載の発明）。また、断面低減率についても、第４以降の円周方向部材はすべてモデルと比して同一面積で実施しているがこれに限定されず、半径方向の内方に向かって段階的に減少させて実施しても良い。
【００２１】
請求項１および請求項２に記載した鉄骨造の大空間屋根構造の構築工法及び鉄骨造の大空間屋根構造は、上記実施例３に特に記載したとおり、構造力学的にも支障なく屋根鉄骨総重量の軽量化を図ることができ、それに伴い下部躯体の構造部材の軽量化を図ることができ、その結果、大幅なコストダウンを達成することができる。また、最外周付近のみならずその内側部分の円周方向部材にも荷重をバランス良く負担させることができるので、経済的な設計が可能となる。
【図面の簡単な説明】
【図１】Ａは、本発明に係る鉄骨造の大空間屋根構造を概略的に示した平面図であり、Ｂは、同正面図である。
【図２】Ａは、実施例１に係る鉄骨造の大空間屋根構造を平面的に見た状態で、半径方向のある断面での各部材の軸力をｔｏｎ表示で示し、且つ、図中に円周方向部材３ａ，３ｂ，３ｃの軸応力度と、長期許容応力度に対する軸応力度の比率を示している。Ｂは、実施例１に係る鉄骨造の大空間屋根構造を平面的に見た状態で、半径方向のある断面での各部材のモーメントを示している。Ｃは、実施例１に係る鉄骨造の大空間屋根構造の変形状態を示している。
【図３】Ａは、実施例２に係る鉄骨造の大空間屋根構造を平面的に見た状態で、半径方向のある断面での各部材の軸力をｔｏｎ表示で示し、且つ、図中に円周方向部材３ａ，３ｂ，３ｃの軸応力度と、長期許容応力度に対する軸応力度の比率を示している。Ｂは、実施例２に係る鉄骨造の大空間屋根構造を平面的に見た状態で、半径方向のある断面での各部材のモーメントを示している。Ｃは、実施例２に係る鉄骨造の大空間屋根構造の変形状態を示している。
【図４】Ａは、実施例３（本発明）に係る鉄骨造の大空間屋根構造を平面的に見た状態で、半径方向のある断面での各部材の軸力をｔｏｎ表示で示し、且つ、図中に円周方向部材３ａ，３ｂ，３ｃの軸応力度、長期許容応力度に対する軸応力度の比率を示している。Ｂは、実施例３に係る鉄骨造の大空間屋根構造を平面的に見た状態で、半径方向のある断面での各部材のモーメントを示している。Ｃは、実施例３に係る鉄骨造の大空間屋根構造の変形状態を示している。
【図５】各鋼材の種類と許容応力度を示している。
【符号の説明】
１鉄骨造の大空間屋根構造
２半径方向部材
３，３ａ，３ｂ，３ｃ，３ｄ，３ｅ円周方向部材[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a construction method of a steel structure large space roof structure and a steel structure large space roof structure, and more specifically, the weight of the roof steel frame can be reduced, and accordingly, the lower casing The present invention relates to a construction method of a steel-framed large space roof structure and a steel-framed large space roof structure capable of reducing the weight of a structural member.
[0002]
[Prior art]
A steel structure large space roof structure is generally disclosed in JP-A-6-288008, JP-A-8-144371, JP-A-11-1989, etc. It is comprised from the circumferential direction member arrange | positioned concentrically.
[0003]
By the way, in order to reduce the total weight of the roof steel frame, it is necessary to reduce the cross-sectional area of each member by disposing members made of high-strength high-strength steel in each of the radial member and the circumferential member. Is valid.
[0004]
[Problems to be solved by the present invention]
However, in fact, when high-strength steel is installed in the radial member, usually the buckling load due to compression is dominant in most radial members, so the Young's modulus and buckling strength are only as high as those of mild steel. There is not much meaning to arrange the tensile steel. On the other hand, a circumferential member, particularly a circumferential member (tension ring) disposed on the outermost periphery has an advantage of disposing a member made of high-strength steel because only a tensile load acts.
Therefore, if only the tension ring is implemented with a member made of high-strength steel having twice the normal strength, the cross-sectional area of the tension ring can be implemented in substantially the same way with a size of about 1/2, so that the total weight of the roof steel frame It seems to be able to reduce the weight.
[0005]
However, in terms of structural mechanics, the axial rigidity of the tension ring is halved, and the radial rigidity in the roof structure is suddenly changed, so that the tensile stress of one adjacent circumferential member increases. Therefore, it is necessary to increase the cross-sectional area of the circumferential member, and it cannot be said that the total weight of the roof steel frame is substantially reduced.
In general, the circumferential member tends to act only on the circumferential member disposed near the outermost periphery, and the circumferential member on the inner part is often not effectively utilized. It was an uneconomic design.
[0006]
Therefore, the object of the present invention is to reduce the total weight of the roof steel frame without any trouble in structural mechanics. Accordingly, it is possible to reduce the weight of the structural member of the lower housing, resulting in a significant cost. An object of the present invention is to provide a construction method for a steel-framed large space roof structure and a steel-framed large space roof structure capable of achieving down.
The next object of the present invention is to construct a steel-structured large space roof structure that can load a load in a balanced manner not only in the vicinity of the outermost periphery but also in the circumferential member of the inner portion thereof, and a steel-structured large space roof To provide a structure.
[0007]
As a means for solving the above-mentioned problems of the prior art, a construction method of a steel structure large space roof structure according to the invention described in claim 1 is:
In the construction method of a steel structure large space roof structure composed of radial members and circumferential members arranged concentrically,
Of the circumferential members, the outermost circumferential member is composed of the highest strength steel grade such as high-tensile steel, and the plurality of circumferential members on the inner side are each strength inward in the radial direction. The axial stress with respect to the long-term allowable stress of each circumferential member is configured by gradually reducing the stiffness of each circumferential member inward in the radial direction. It is characterized by constructing a structure in which the load of the roof structure is borne in a balanced manner on each circumferential member by reducing the variation in the degree ratio .
[0008]
Steel structure large space roof structure according to the invention described in claim 2,
In the steel structure large space roof structure composed of radial members and circumferential members arranged concentrically,
Among the circumferential members, the outermost circumferential member is composed of the highest strength steel grade such as high-tensile steel, and the plurality of circumferential members on its inner side are each strength inward in the radial direction. The axial stress relative to the long-term allowable stress of each circumferential member is configured by gradually reducing the rigidity of each circumferential member inwardly in the radial direction. By reducing the variation in the ratio of degrees, it is constructed in a structure in which the load of the roof structure is borne in a balanced manner on each circumferential member .
[0010]
1A and 1B schematically show a construction method of a steel structure large space roof structure and a steel structure large space roof structure according to claims 1 and 2 .
The construction method of the steel-structured large space roof structure 1 composed of the radial member 2 and the circumferential member 3 arranged concentrically as described in claim 1 outermost circumferential member 3a constitute the most high strength steels due high tensile steel (tension ring), a plurality of circumferential members 3b of the inner, 3c, 3d, 3e ... respectively, radially of strength constituted by stepwise smaller the steels inwardly, and, step by step toward the inside in the radial direction by varying the stiffness of the circumferential member, each of said circumferential member It is characterized by constructing a structure in which the load of the roof structure is borne in a balanced manner on each circumferential member by reducing the variation (change rate) of the ratio of the axial stress to the long-term allowable stress of (Invention of Claim 1)
[0011]
The steel-structured large space roof structure 1 constructed by the construction method described above includes a member made of the highest strength steel material such as high-strength steel in the outermost first circumferential member 3a of the circumferential members 3 ( A tension ring is provided, and a member made of a steel material having a lower strength than the first circumferential member 3a is arranged on the second circumferential member 3b on the inner side thereof, and a third member on the inner side thereof is further provided. Subsequent circumferential members 3c, 3d, 3e, ... are provided with steel members having lower strength than the second circumferential member 3b.
[0012]
Furthermore, compared with the model which comprised the said circumferential direction member 3 by all the steel grades of the same intensity | strength, and designed the stable large-sized steel roof structure, about the cross-section reduction rate of the corresponding circumferential direction member 3, respectively. The cross-sectional reduction rate of the first circumferential member 3a is approximately 50%, and the cross-sectional reduction rate of the second circumferential member 3b is compared with the cross-sectional reduction rate of the first circumferential member 3a. reduced Te, third and subsequent circumferential member 3c, 3d, 3e ... sectional reduction rate of that is the same or reduced compared to the cross-sectional reduction ratio of the second circumferential member 3b.
[0013]
Hereinafter, based on the concrete Examples 1-3, the effect of the steel structure large space roof structure 1 constructed | assembled by the said construction method is examined. Incidentally, Example 1 shows a model constructed by constructing all the circumferential members 3 with the same strength steel type, and Example 2 is twice the outermost circumferential member only as compared with Example 1. Example 3 shows a case where it is constructed with a steel type having strength, and in Example 3, compared with Example 2, the rigidity is reduced toward the inner member in the circumferential direction from the outermost periphery toward the inner side in the radial direction. It shows an example of a case constructed and composed steels.
[0014]
<Example 1 (original design)>
FIGS. 2A to C show a steel structure large space roof having a diameter of 200 m and a height of 32 m, and all the circumferential members 3a, 3b, 3c... Designed with the same strength (steel material type: SM490 (see FIG. 5)). It shows the structure. The load was 107.8 kN / m ³ for the structural member, 735 N / m ² for the finishing material, and the total weight was about 6.44 × 10 ⁴ kN. In this design, the outermost circumferential member (tension ring) 3a has an outer diameter of 800 mm and a wall thickness of 45 mm, and all other members are made of H steel (300 mm × 300 mm × 10 mm × 15 mm) on the upper and lower chords. The truss was 2m high.
FIG. 2A shows the axial force of each member in the radial cross section of the roof structure in ton, and the axial stress degree of the circumferential members 3a, 3b, 3c and the axial stress degree with respect to the long-term allowable stress degree (ft). The ratio (hereinafter referred to as “ratio” where appropriate) is shown. The shaft stresses and ratios about each circumferential members 3a, 3b, for 3c, is 101N / mm ² and 0.47,62N / mm ² and 0.29,20N / mm ² and 0.09. FIG. 2B similarly showed the moment. FIG. 2C shows the deformation, which is deformed by a weight of 11.4 cm at the center position in the vertical direction and deformed by 4.9 cm at the outermost periphery in the radial direction.
[0015]
<Example 2>
Example 2 shown in FIGS. 3A to 3C has a steel type HT780 having a strength twice that of the steel type SM490 in the outermost circumferential member (tension ring) 3a as compared with Example 1 described above. The only difference is that 5) is applied. By using this steel type: HT780, the cross-sectional area of the member can be reduced to substantially half the outer diameter of 800 mm and the wall thickness of 21.8 mm. Therefore, only the circumferential member 3a can be reduced in weight.
[0016]
As shown in FIG. 3A, the axial stress degree (N / mm ² ) of the member of the tension ring 3a is about 174/101 = 1.72 times that of the first embodiment, and the ratio is that of the first embodiment. It is smaller than 0.47 and becomes about 0.40. However, the axial stresses of the adjacent inner circumferential members 3b and 3c are 111/62 = 1.79 times and 45/20 = 2.25 times, respectively. The area is forced to increase, and the overall weight of the roof steel frame cannot be reduced as a whole.
[0017]
This is considered to be due to the stress acting on the outermost tension ring 3a flowing in the circumferential members 3b and 3c due to the sudden change in rigidity with respect to Example 1. Further, the ratio of the circumferential member 3b is about 0.51, and the safety of the member is somewhat lacking. Incidentally, as shown in FIG. 3C, the deformation is deformed by the weight of 17.2 cm at the center position in the vertical direction, and deformed by 8.5 cm at the outermost periphery in the radial direction. .
[0018]
<Example 3>
Example 3 shown in FIGS. 4A to 4C shows an example of a steel-framed large space roof structure described in claim 3, as compared with Example 2 above, from the outermost circumferential member 3 a. The only difference is that steel materials having several different strengths shown in FIG. 5 are used for the inner circumferential members 3b, 3c. Specifically, the first circumferential member 3a is HT780, the second circumferential member 3b is SA440, the third circumferential member 3c is SM520, the fourth and subsequent circumferential members are SM490, While changing the kind of steel material to a low intensity | strength toward inner side of radial direction from outermost periphery, the cross-sectional reduction of the circumferential direction members 3a, 3b, 3c, 3d ... corresponding to the circumferential direction member of Example 1 is carried out. The rates are 50%, 47%, 47%, and 0%, respectively. Here, in order to obtain a stable steel frame large space roof structure, the ratio of the acting stress to the long-term allowable tensile stress (ft) is set to 0.5 or less.
[0019]
As a result, compared with Example 1 above, the ratio is almost unchanged from 0.47 to about 0.42. However, in the circumferential members 3b and 3c, they are about 0.44 with respect to 0.29 and about 0.26 with respect to 0.09, respectively, and the rate of change (variation) inward in the radial direction. Is reduced, the strength of the member can be increased and the circumferential member of the inner part can be effectively used, and the total weight of the roof steel frame can be reduced by about 11% compared to Example 1 (original design). did it. Further, there is no circumferential member whose stress changes suddenly by gradually changing the rigidity of the circumferential member, and the load is applied to the circumferential member not only near the outermost periphery but also in the inner portion thereof in a well-balanced manner. I was able to. Incidentally, as shown in FIG. 4C, the deformation is deformed by the weight of 18.6 cm at the center position in the vertical direction and deformed by 8.9 cm at the outermost periphery in the radial direction, which is within the allowable range in terms of structural mechanics. .
[0020]
As a result, when a large force acts on the tension ring such as a large-scale structure or a special structure, it can be easily predicted that a greater reduction effect can be obtained.
In Example 3 described above, the steel members (SM490) having the same strength are all arranged in the fourth and subsequent circumferential members to construct a steel structure large space roof structure. A member made of steel whose rigidity is gradually reduced may be arranged and carried out (invention according to claim 2). In addition, the cross-section reduction rate is all the same for the fourth and subsequent circumferential members as compared with the model, but is not limited to this, and is gradually reduced inward in the radial direction. May be implemented.
[0021]
The construction method of the steel structure large space roof structure described in claim 1 and claim 2 and the steel structure large space roof structure are the same as described in Example 3 above. The weight can be reduced, and accordingly, the structural member of the lower casing can be reduced, and as a result, a significant cost reduction can be achieved. Moreover, since the load can be borne not only in the vicinity of the outermost periphery but also in the circumferential member in the inner portion thereof in a balanced manner, an economical design is possible.
[Brief description of the drawings]
FIG. 1A is a plan view schematically showing a steel structure large space roof structure according to the present invention, and B is a front view thereof. FIG.
FIG. 2A shows the axial force of each member in a radial cross-section in a state viewed in a plan view of the steel-structured large space roof structure according to Example 1, and in FIG. 3 shows the ratio of the axial stress degree of the circumferential members 3a, 3b, and 3c to the long-term allowable stress degree. B shows the moment of each member in the cross section with a radial direction in the state which looked at the steel frame large space roof structure concerning Example 1 planarly. C has shown the deformation state of the steel structure large space roof structure which concerns on Example 1. FIG.
FIG. 3A is a view showing the axial force of each member in a radial cross section in a ton display in a state where the steel structure large space roof structure according to the second embodiment is viewed in a plan view; 3 shows the ratio of the axial stress degree of the circumferential members 3a, 3b, and 3c to the long-term allowable stress degree. B shows the moment of each member in a certain cross section in the radial direction in a state where the steel structure large space roof structure according to the second embodiment is viewed in a plane. C has shown the deformation | transformation state of the steel structure large space roof structure which concerns on Example 2. FIG.
FIG. 4A is a view showing the axial force of each member in a radial cross section in a ton display in a state where the steel structure large space roof structure according to Example 3 (the present invention) is viewed in a plane. Moreover, the ratio of the axial stress degree to the axial stress degree of the circumferential members 3a, 3b, 3c and the long-term allowable stress degree is shown in the figure. B shows the moment of each member in a cross section with a radial direction in the state which looked at the steel frame large space roof structure concerning Example 3 planarly. C shows a deformed state of the steel structure large space roof structure according to the third embodiment.
FIG. 5 shows the types and allowable stresses of each steel material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel structure large space roof structure 2 Radial direction member 3, 3a, 3b, 3c, 3d, 3e Circumferential direction member

Claims

In the construction method of a steel structure large space roof structure composed of radial members and circumferential members arranged concentrically,
Of the circumferential members, the outermost circumferential member is composed of the highest strength steel grade such as high-tensile steel, and the plurality of circumferential members on the inner side are each strength inward in the radial direction. The axial stress with respect to the long-term allowable stress of each circumferential member is configured by gradually reducing the stiffness of each circumferential member inward in the radial direction. A construction method for a steel-structured large space roof structure, characterized in that it is constructed in a structure that balances the load of the roof structure on each circumferential member by reducing the variation in the ratio of degrees .

In the steel structure large space roof structure composed of radial members and circumferential members arranged concentrically,
Among the circumferential members, the outermost circumferential member is composed of the highest strength steel grade such as high-tensile steel, and the plurality of circumferential members on its inner side are each strength inward in the radial direction. The axial stress relative to the long-term allowable stress of each circumferential member is configured by gradually reducing the rigidity of each circumferential member inwardly in the radial direction. A steel-structured large space roof structure characterized by being constructed in a structure in which the load of the roof structure is borne in a balanced manner on each circumferential member by reducing the variation in the ratio of degrees .