JP2004028626A - Strain gage type external force measuring device and external force measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly durable/reliable strain gage type external force measuring device constituted by having strain gages forming a bridge circuit, capable of measuring an external force highly accurately to the utmost even if a failure is generated in some strain gage, and its external force measuring method. <P>SOLUTION: This device is equipped with a strain member deforming elastically by an external force, the strain gages 42 forming the bridge circuit 43 by being stuck on the strain member, and a measuring device 55 (55a, 55b) for calculating the external force applied to the strain member based on the output of the bridge circuit. At least two bridge circuits are formed independently, and the measuring device has a plurality of channels to be connected respectively to each bridge circuit, calculates external force values in each channel, determines the mean value thereof, and outputs the mean value as the measured value. The measuring device calculates/stores a ratio of the external force value in each bridge circuit to the measured value as a sharing ratio based on the measured value and the external force value calculated in each bridge circuit, If a failed bridge circuit exists, the device acquires the mean value of values determined by dividing the calculated value in each other sound bridge circuit by each sharing ratio and outputs it as the measured value. <P>COPYRIGHT: (C)2004,JPO

Description

【００４７】
次ぎに、以上のように構成されるロードセル３０の耐久性と多系統計測法の作用・効果について述べる。
＜１＞ロードセルの耐久性について
歪みゲージ式のロードセル３０は、そもそも機械的な可動部分をもたない構造のため、本質的に長期安定性に優れている。特に本実施形態のようなＰＣＣＶテンドン張力測定に用いる場合、ロードセル３０は外気と遮断されたエンドキャップの中に設置され、グリスで満たされている。また、働く荷董は容量のほぼ８０％で一定とされる。これらの環境条件はロードセル３０にとって極めてよい環境であるといえ、ロードセル３０の耐用年数は非常に長いものとなる。
【００４８】
ここでロードセル３０を、更にこれを構成する各要素に分けてその耐久性を考えると、次のようになる。
１）歪み部材について
歪み部材３１は荷重を受けて弾性変形を生じる部分であるが、金属で一体となった構造であることと、働く荷重が容量のほぼ８０％で一定であることから故障が生じることはないと考えられる。
【００４９】
２）歪みゲージ、接着剤、コーティング材、結線部について
歪みゲージ４２は歪み部材３１に生じる弾性変形を電気的に検出する部分である。金属、樹脂などによって構成され、仮に湿気の浸入などにより故障を生じると正確な動作ができなくなり、ロードセル３０の機能が損なわれる。しかし本実施形態では、歪みゲージ４２の取り付け部分は図３及び図８に示すような構造となっており、これらが外気にさらされることはない。従って故障を生じる確率は非常に低いが、さらに後述する「多系統計測法」を採用することにより、ロードセル３０としての故障に結びつくことを事実上なくすことができる。
また、歪みゲージ４２は貫通孔部３６の内壁に取り付けられる。貫通孔部３６は蓋および０リングによりシールされ、外気と完全に遮断されている。
【００５０】
３）入出力ケーブル〈エンドキャップ内）について
ロードセル３０内部の回路と外部に設けた歪み測定器５５ａとの間を電気的に接続する部分であり、機械的な損傷を受けること等により故障すると測定に支障をきたすことがある。ただし、本実施形態においてはエンドキャップ内の入出力ケーブル５４は取り付けられた状態で静置され、被覆されているので取付けた時に故障がなければプラント寿命中に問題になることはない。
【００５１】
以上のことから、本実施形態におけるロードセル３０の耐久性については、歪みゲージ４２、接着剤、コーティング材、結線部を考慮する。そして「多系統計測法」という計測方法を採用することにより、ロードセル３０としての故障を事実上なくすことが可能となる。
【００５２】
即ち、本実施形態における「多系統計測法」とは、独立した６つのブリッジ回路４３を形成して６系統となし、通常はそれら６系統のブリッジ回路出力の平均値をもって測定値とするとともに、仮にいずれかの歪みゲージ４２の故障によってある系統のブリッジ回路が測定不能となった場合には、残りの健全なブリッジ回路からの出力に基づく算出値の平均値を求めて、当該平均値を計測値とするというものである。これによって、歪みゲージ４２の故障がロードセル３０全体としての故障につながる率を可及的に低下させることが可能になる。
【００５３】
つまり、どれかひとつの歪みゲージ４２が故障しても、それが組み込まれたブリッジ回路４３が測定不能となるだけで、他のブリッジ回路４３は測定可能である。そして、多系統計測法においては、複数のブリッジ回路出力に基づく算出値の平均値を求めてこれを計測値とすることから、残った健全なブリッジ回路出力に基づいて平常時とほぼ同じ測定値が得られるようになる。
【００５４】
ここで、歪み部材３１の複数の起歪部にかかる力が一様でなければ、そこに誤差を生じることになるが、一般に荷重のかかり始めでは各起歪部の負担荷重はバラツキが大きいものとなるが、今回はほぼ一定荷重がかかった状態での測定であるので、各起歪部の荷重分担率が大きく変わることはない。そのため、残りの各ブリッジ回路出力に基づいて算出した算出値に、それまでの荷重分担率を考慮して加重平均値を取れば、誤差を可及的に小さくして、十分に有効な極めて高精度なデータが得られるようになる。あるいは、加重平均でなく単純平均をとったとしても、多少の精度の低下があるだけで実用上は十分なデータが得られる。
【００５５】
一方、ロードセル３０が故障する原因は、一般の場合はほとんどすべてが過負荷、ケーブルの損傷、湿気の浸入などの外的要因によるものである。これらに対しては多系統化しても故障率の引き下げは必ずしも期待できない。例えば過負荷では歪み部材３１が正常な特性を失うので、複数のブリッジ回路４３があってもそれらすべてが故障してしまう。しかし本実施形態では、これらの外的要因による不良は考えられない。
【００５６】
すなわち、荷重は容量のほぼ８０％が常にかかった状態であり、過負荷はない。またロードセル３０は取り付けられた状態で静置されるのでケーブル５４の損傷もない。さらにロードセル３０はグリスキャップ内に取り付けられるので外気とほほ完全に遮断される。これらの理由により、本実施形態において危倶されるのは歪みゲージ４２などの回路部に起因する故障であり、当該回路部の故障に対しては多系統化による故障率の引き下げが有効となる。
【００５７】
多系統化によるロードセル３０自体のコストについては、起歪部の形状や歪みゲージ点数などが変わらなければ、コスト上昇はさほど大きくない。
【００５８】
＜２＞多系統計測法における故障率
▲１▼すべての系統が故障する確率
ここでは、ロードセル３０の故障は歪みゲージ４２の故障によるもの、のみとし、その歪みゲージ４２の故障率がロードセル３０の故障率に与える影響を考える。但し、歪みゲージ４２の故障は独立事象とし、ロードセル３０の故障はすべての系統のブリッジ回路が測定不能となったときとする。
【００５９】
ここで、１枚の歪みゲージがある期間に故障する確率をα、ブリッジ回路の系統数をｍ、歪みゲージの枚数（エレメント数）をｎ（ただし、ｎ／４ｍ：整数）とすると、歪みゲージの故障によってロードセルが故障する確率βは、
【数２】

となる。
【００６０】
歪みゲージ４２の枚数（エレメント数）ｎを２４とすると、取り得るブリッジの系統数ｍは、ｍ＝１，２，３，６となる。但し、ロードセルが半割れ型であることから製造上の間題を考慮してｍ＝３は除外する。
【００６１】
歪みゲージの故障率αの見積もりは大変難しいが、仮に６０年間で３％が故障すると仮定すると、ｍ＝１，２，６でのβは▲１▼式より、
【数３】

となる。
【００６２】
従ってブリッジ系統数１に対する２系統６系統の故障率はそれぞれ
【数４】

となる。
【００６３】
つまり故障率は２系統にすることで約５分の１、６系統にすることで約２０万分の１になる。これは、多系統化した場合には全部の系統が故障しない限り若干の精度の低下はあっても測定不能とはならないので、結果として故障率を著しく下げることができることになる。また、ロードセル３０の故障率βは歪みゲージ４２の故障率αによって決まるものであるが、歪みゲージ４２自体が外的要因によらずに故障する確率として、６０年間で３％という数値は余裕のあるものと考えられる。
【００６４】
▲２▼一部の系統が故障する確率
６系統とした場合に全部の系統が故障する確率はほぼゼロであるが、一部の系統が故障する確率を求めてみると次のようになる。
【００６５】
１枚の歪みゲージがある期間に故障する確率をα、ブリッジの系統数をｍ、歪みゲージの枚数（エレメント数）をｎ（ただし、ｎ／４ｍ：整数）、ひとつのブリッジ回路４３が故障する確率をγとすると、
【数５】

【００６６】
となる。
【００６７】
ここでｍ系統中ｐ系統のブリッジ回路４３が故障する確率をδとすると、
【数６】

【００６８】
となる。
【００６９】
ただしここに、
【数７】

【００７０】
である。
【００７１】
ｍ＝６、ｎ＝２４、α＝０．０３としてｐ＝０、１、２、３、４、５、６のときのδを求めると
δ_{ｐ＝ ０}＝｛１−（１−０．０３）^２４／６｝^０（１−０．０３）^{２４（６−０）／６}×_６Ｃ_０＝０．４８
δ_{ｐ＝ １}＝｛１−（１−０．０３）^２４／６｝^１（１−０．０３）^{２４（６−１）／６}×_６Ｃ_１＝０．３７
δ_{ｐ＝ ２}＝｛１−（１−０．０３）^２４／６｝^２（１−０．０３）^{２４（６−２）／６}×_６Ｃ_２＝０．１２
δ_{ｐ＝ ３}＝｛１−（１−０．０３）^２４／６｝^３（１−０．０３）^{２４（６−３）／６}×_６Ｃ_３＝２．１×１０^−２
δ_{ｐ＝ ４}＝｛１−（１−０．０３）^２４／６｝^４（１−０．０３）^{２４（６−４）／６}×_６Ｃ_４＝２．０×ｌ０^−３
δ_{ｐ＝ ５}＝｛１−（１−０．０３）^２４／６｝^５（１−０．０３）^{２４（６−５）／６}×_６Ｃ_５＝１．１×ｌ０^−４
δ_{ｐ＝ ６}＝｛１−（１−０．０３）^２４／６｝^６（１−０．０３）^{２４（６−６）／６}×_６Ｃ_６＝２．３×１０^−６
となる。
【００７２】
上記のように、全部の系統が故障しない確率は約４８％、１系統のみ故障する確率は約３７％、２系統が故障する確率は約１２％、３系統が故障する確率は約２％となり、この４つのケースの合計で約９９％となる。つまり、約９９％の確率で３系統以上の測定が可能である。一方、６系統すべてが故障する確率は５０万分の１以下であり、事実上皆無と言える。以上のように、多系統計測法を採用することによって故障率を非常に小さくすることができる。
【００７３】
【発明の効果】
以上に詳しく説明したように、本発明に係る歪みゲージ式外力測定装置およびその測定方法にあっては、次のような格別な効果を奏する。
【００７４】
（１）外力を受けて弾性変形する歪み部材に歪みゲージを貼設して複数系統のブリッジ回路を構成し、この各ブリッジ回路を測定器の複数のチャンネルに接続して個別に外力値を算出し、これらの算出値の平均値を算出して、計測値とするので、いずれかの歪みゲージが故障しても、それが組み込まれた系統のブリッジ回路が測定不能となるだけで、少なくともいずれか１つの系統のブリッジ回路が測定可能であれば、その健全なブリッジ回路によって外力を測定することができ、歪みゲージ式外力測定装置が測定不能となる確率を可及的に低減でき、その耐久性の大幅な向上が図れる。
【００７５】
（２）複数のブリッジ回路出力に基づく算出値の平均値を求めてこれを計測値とすることから、歪み部材の起歪部の形状や歪みゲージの感度のバラツキ、荷重の偏在などに起因した誤差を可及的に小さくすることができ、高精度な信頼度の高い計測値を得ることができるようになる。
【００７６】
（３）また、前記計測値と各ブリッジ回路毎の外力値の比率を分担率として記憶しておき、故障したブリッジ回路がある場合には、他の健全なブリッジ回路の算出値をそれぞれの分担率で除した値の平均値を算出して、当該平均値を計測値として出力するようにすれば、測定不能な系統が生じた場合にも、その計測誤差が大きくなってしまうことを可及的に防止でき、高精度な信頼度の高い計測値を得ることができるようになる。
【００７７】
（４）緊張線材の端部に設けられた係止部材と定着対象部との間に歪み部材を介設して、緊張線材からの緊張力を定着対象部に伝達するとともに、その緊張力に応じたせん断歪みを歪み部材に生じさせて、この歪み部材のせん断歪み量を歪みゲージで検出して緊張線材の張力を測定するようにすれば、適宜必要な時にいつでも張力測定を行うことができ、もって原子炉格納容器の緊張線材の張力測定に適用すれば、定期的な張力測定作業をきわめて容易に済ませることができるようになる。
【００７８】
（５）前記係止部材に当接されて前記緊張線材の緊張力を受圧する内周部と、前記定着対象部側に当接されて前記緊張力を前記定着対象部側に伝達する外周部と、これら内周部と外周部との間を連結して介設され、前記せん断歪みが生ずる梁部と、前記内周部に設けられ前記緊張線材が挿通される挿通穴部とを備えて歪み部材を構成することで、緊張線材の緊張力に応じたせん断歪みを梁部に生じさせることができ、当該梁部に前記歪みゲージを設けることによって、緊張線材の緊張力を精度よく簡単に検出することができる。
【００７９】
（６）前記歪み部材を、複数の分割片によって構成することによって、係止部材と定着対象部の間からの撤去作業や取り付け作業を容易に行うことができる。
【図面の簡単な説明】
【図１】本発明に係る外力測定装置が、緊張線材の定着部に介設されるプレストレストコンクリート製原子炉格納容器（ＰＣＣＶ）の外観を示した全体斜視図である。
【図２】図１に示すプレストレストコンクリート製原子炉格納容器の外壁部の断面構造を示した部分断面斜視図である。
【図３】本発明に係る外力測定装置が取り付けられる緊張線材の定着部の一実施形態を示した断面図である。
【図４】緊張線材の定着部に取り付けられる本発明に係る外力測定装置のロードセルの一実施形態を示した平面図である。
【図５】緊張線材の定着部に取り付けられる本発明に係る外力測定装置のロードセルの一実施形態を示した断面図である。
【図６】図５のロードセルの起歪部に貼設される２４個の歪みゲージを説明する図である。
【図７】６系統の独立したブリッジ回路に形成された２４個の歪みゲージの各素子の組み合わせを示す回路図である。
【図８】本発明に係る外力測定装置を既存の定着部に置き換えて施工する場合の施工手順を示した説明図である。
【図９】本発明に係る外力測定装置を新設の緊張線材の定着部に設ける場合の施工方法を説明するための説明図である。
【図１０】ロードセルの概略構成を示す断面図である。
【図１１】従来の４つの歪みゲージで形成される基本的なブリッジ回路を示す図である。
【図１２】２４個の素子の歪みゲージで１つのブリッジ回路を形成した場合を示す図である。
【符号の説明】
１０　原子炉格納容器
１２　下部コンクリート構造体
１４　上部コンクリート構造体
１６　鉄筋
１８　ＰＣ鋼線（緊張線材）
２０　シース管
２６　アンカーヘッド（係止部材）
３０　ロードセル
３１　歪み部材
３２　挿通穴部
３４　内周部
３６　貫通孔部
３８　外周部
３９　支圧板
４０　梁部
４２　歪みゲージ
４３　ブリッジ回路
５０　エンドキャップ
５２　防錆材
５５　測定器
５５ａ　歪み測定器
５５ｂ　コンピュータ装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a strain gauge in which a strain gauge that forms a bridge circuit is attached to a strain member that is elastically deformed by the application of an external force, and the external force applied to the strain member is calculated by a measuring device based on the output of the bridge circuit. The present invention relates to a gauge type external force measuring device and a measuring method thereof.
[0002]
[Prior art]
Conventionally, a tension wire such as a PC steel wire is inserted into a concrete structure to introduce a tension into the tension wire to pre-stress the concrete structure. A structure called a prestressed concrete structure (PC structure) for increasing the strength of the body is known. This prestressed concrete structure has been favorably implemented in structures requiring a higher level of safety than before, such as reactor containment vessels of nuclear power plants.
[0003]
By the way, in a reactor containment vessel constructed of a prestressed concrete structure, since a high level of safety is always required, a certain period of time, e.g., one year, three years, or ten years, has passed since construction. It is required to periodically check whether sufficient tension is applied to a tension wire applied to a prestressed concrete structure. Conventionally, in this inspection work, a tension jack was attached to the end of the tension wire, and the tension wire was pulled to measure the residual tension. Work had to be done. For this reason, the maintenance cost has been significantly increased.
[0004]
Therefore, the present applicants have been developing a measuring device capable of measuring the tension of the tension wire at any time without performing the above-mentioned complicated work. That is, as shown in FIGS. 10 and 11, the measuring device includes a strain member a elastically deformed by the tension of a tension wire whose end is fixed to a given fixing target portion; And a measuring device c for calculating the external force input to the strain member a from the output of the strain member b. The strain member a and the strain gauge b are so-called load cells. d.
[0005]
Here, the load cell d basically forms a bridge circuit e with four element strain gauges b1 to b4. In the case of a load cell having a plurality of strain-generating portions (places where strain gauges are stuck) on the strain member a, the load cell 4 In general, one bridge circuit e is formed using multiple (4n) strain gauges b. For example, in a case where 24 strain gauges b are attached to a predetermined position of a strain member a and a bridge circuit e is formed by the 24 strain gauges b, conventionally, as shown in FIG. The three strain gauges b1 to b24 are combined in series and connected in series, and the set of three is further joined in parallel to constitute one bridge circuit e.
[0006]
As described above, when one bridge circuit e is formed using a number of strain gauges b1 to b24, the detection values of the respective strain gauges b1 to b24 in the bridge circuit e are averaged and output by the operation of the bridge circuit e. Therefore, the linearity of the output characteristics of the load cell d can be improved.
[0007]
[Problems to be solved by the invention]
However, in the case where one bridge circuit e is formed by a large number of strain gauges b1 to b24 as shown in FIG. 12, even if one of the 24 strain gauges b1 to b24 fails, the bridge circuit e is failed. Does not function properly, resulting in failure of the load cell d. That is, if any one of the strain gauges b1 to b24 fails, the balance of the bridge circuit e is lost and normal operation becomes impossible, so that accurate external force measurement cannot be performed. There was room for improvement in terms of durability and reliability.
[0008]
The present invention has been made in view of such circumstances, and an object of the present invention is to use a multiple of four strain gauges forming a bridge circuit and to cause a failure in any one of the strain gauges. It is an object of the present invention to provide a durable and reliable strain gauge type external force measuring device and a method for measuring the external force, which can measure the external force with as high accuracy as possible.
[0009]
[Means for Solving the Problems]
In order to achieve such an object, in the present invention, a strain gauge type external force measuring device and a measuring method thereof are configured as follows.
[0010]
In the strain gauge type external force measuring device according to claim 1, based on the output of the bridge member, a strain member which is elastically deformed by an external force applied thereto, forms a bridge circuit, and is attached to the strain member. A measuring device for calculating an external force applied to the distortion member, wherein at least two or more bridge circuits are independently formed, and the measuring device includes a plurality of bridge circuits each of which is individually connected. And calculating an external force value for each of the plurality of channels, calculating an average value of the plurality of external force values, and outputting the average value as a measured value.
[0011]
In the strain gauge type external force measuring device according to claim 2, the measuring device stores a ratio of the external force value of each bridge circuit to the measured value as a sharing ratio, and when there is a failed bridge circuit, another soundness is obtained. The average value of the values obtained by dividing the calculated values of the bridge circuits by the respective sharing ratios is output as the measured value.
[0012]
According to a third aspect of the present invention, in the strain gauge type external force measuring device according to the first or second aspect, the distortion member is a locking member provided at an end of a tension wire to which tension is applied and an end of the tension wire. The tension force of the tension wire is measured by being interposed between the fixing target portion and the fixing portion.
[0013]
According to a fourth aspect of the present invention, in the strain gauge type external force measuring device according to the third aspect, the distortion member is in contact with the locking member to receive a tension of the tension wire, and the fixing target An outer peripheral portion that is in contact with the portion side and transmits the tension to the fixing target portion side, a beam portion in which the inner peripheral portion and the outer peripheral portion are connected and interposed, and the shear strain occurs, An insertion hole provided in the inner peripheral portion, through which the tension wire is inserted, and the strain gauge is provided in the beam.
[0014]
According to a fifth aspect of the present invention, in the strain gauge type external force measuring device according to the fourth aspect, the distortion member is constituted by a plurality of divided pieces.
[0015]
In the external force measuring method according to claim 6, a strain gauge that forms a bridge circuit is attached to a strain member to which an external force is applied and elastically deformed, and an external force applied to the strain member based on an output of the bridge circuit is measured. In a method for measuring an external force calculated and obtained by a measuring device, a plurality of bridge circuits are provided, an external force is calculated for each bridge circuit, and an average value of the calculated values is used as a measured value.
[0016]
In the external force measuring method according to claim 7, in claim 6, the ratio of the external force value for each bridge circuit to the measured value is calculated and stored as a sharing ratio. The calculated value of the healthy bridge circuit is divided by the respective sharing ratios, and an average value of the divided values is used as a measured value.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a strain gauge type external force measuring device and a measuring method according to the present invention will be described with reference to the accompanying drawings. FIGS. 1 to 5 show an embodiment in which the external force measuring device according to the present invention is applied to a tension measurement of a tension wire in a prestressed concrete reactor containment vessel (PCCV). FIG. 1 is an external view showing the entire reactor containment vessel, FIG. 2 is a partial sectional perspective view showing a sectional structure of an outer wall portion of the reactor containment vessel, and FIG. It is sectional drawing which showed the fixing structure of the PC steel wire inserted inside the storage container. 4 and 5 are a plan view and a longitudinal sectional view of a load cell for measuring tension attached to the fixing structure portion of the PC steel wire.
[0018]
As shown in FIG. 1, the reactor containment vessel 10 applied here has a cylindrical lower concrete structure 12 built at the lower part and a dome-shaped upper concrete structure integrally built at the upper part thereof. 14. As shown in FIG. 2, a number of PC steel wires 18 are inserted into the lower concrete structure 12 and the upper concrete structure 14 as reinforcing wires such as reinforcing bars 16 as tension wires. The PC steel wire 18 is provided to improve the strength by introducing prestress into the concrete structures 12, 14, and is provided inside the lower concrete structure 12 in the circumferential direction and the height direction. It is arranged along. Further, inside the upper concrete structure 14, PC steel wires 18 are arranged in a mesh shape so as to cross vertically and horizontally along the dome shape.
[0019]
Each PC steel wire 18 is inserted through a sheath tube 20 embedded in the concrete structures 12 and 14 in advance. Both ends of each PC steel wire 18 protrude from the surface portions of the concrete structures 12 and 14, and are fixed to the surface portions of the concrete structures 12 and 14. The PC steel wire 18 inside the lower concrete structure 12 is fixed to a buttress 22 protruding from the outer wall of the lower concrete structure 12 along the height direction. Further, the PC steel wire 18 inside the upper concrete structure 14 passes through the inside of the lower concrete structure 12 and is fixed to a base portion 24 provided at a peripheral edge of a lower end thereof.
[0020]
Tension is applied to each PC steel wire 18, and prestress is introduced into each concrete structure 12, 14, and the strength of the reactor containment vessel 10 is increased to ensure a high level of safety. It is supposed to be.
[0021]
The fixing structure of the PC steel wire 18 will be described. FIG. 3 is an enlarged view of the structure of the fixing portion at both ends of the PC steel wire 18, and a large number of the PC steel wires 18 are inserted into one sheath tube 20. The end 18a of each PC steel wire 18 protrudes from an opening 28 provided on the concrete structure 12, 14 side, and an anchor head 26 is integrally attached thereto as a locking member. The anchor head 26 is provided with a plurality of holes 26a through which the PC steel wires 18 are individually inserted one by one. The PC steel wires 18 are inserted through the respective holes 26a, and the plurality of PC steel wires 18 are inserted. Are bundled and locked.
[0022]
By the way, between the anchor head 26 and the concrete structures 12, 14, a load cell 30 constituting a sensor section of the external force measuring device of the present invention is interposed. The load cell 30 functions as a tension measuring sensor for measuring the tension of the PC steel wire 18, and includes a strain member 31 and a strain gauge 42 as shown in FIGS.
[0023]
The strain member 31 is an annular member having a predetermined thickness formed so as to surround the outer periphery of the PC steel wire 18. One insertion hole 32 through which the wires 18 are inserted collectively is formed through. Outside the insertion hole 32, an inner peripheral portion 34 that is in contact with the anchor head 26 is provided. The strain member 31 receives the tension of the PC steel wire 18 at the inner peripheral portion 34 via the anchor head 26.
[0024]
Further, an annular groove 35 is formed outside the inner peripheral portion 34. The annular grooves 35 are formed substantially coaxially and coaxially on both upper and lower sides of the distortion member 31. The two upper and lower grooves 35 are connected to each other, and a plurality of through-holes 36 are provided in the groove 35 as strain-generating portions for attaching the strain gauge 42. These through-holes 36 are formed at equal intervals along the groove 35, and in the present embodiment, twelve are provided.
[0025]
Further, an outer peripheral portion 38 that is in contact with the concrete structures 12 and 14 is provided outside the groove 35. The outer peripheral portion 38 comes into contact with an annular pressure plate 39 disposed around the opening 28 on the concrete structure 12, 14 side. Thus, the tension of the PC steel wire 18 is received as a load from the anchor head 26 at the inner peripheral portion 34 and transmitted from the outer peripheral portion 38 to the concrete structures 12 and 14.
[0026]
The beam portion 40 is provided between the inner peripheral portion 34 and the outer peripheral portion 38 by forming the twelve through-hole portions 36 as described above. That is, the beam portion 40 connects the inner peripheral portion 34 and the outer peripheral portion 38, and transmits the tension of the PC steel wire 18 from the anchor head 26 to the concrete structures 12, 14. At that time, a shear strain corresponding to the magnitude is generated in the beam portion 40 using the tension as an external force. As shown in FIG. 5, the strain gauge 42 is disposed inside the through-hole portion 36 and detects the amount of shear strain of the beam portion 40. In the present embodiment, two strain gauges 42 are provided in opposition to the inner wall portion of each through-hole portion 36, and a total of 24 strain gauges 42 are provided. By disposing the strain gauge 42 in this manner, the amount of shear strain generated in the beam portion 40 can be detected with high sensitivity. Since the amount of shear strain obtained by this detection is a value corresponding to the tension of the PC steel wire 18, the tension of the PC steel wire 18 can be measured with high accuracy and efficiency.
[0027]
The groove 35 serves to reliably cut off between the anchor head 26 contacting the inner peripheral portion 34 and the concrete structures 12, 14 (supporting plate 39) contacting the outer peripheral portion 38. Plays. That is, as in the present embodiment, the outer diameter of the contact portion 26b with the inner peripheral portion 34 of the anchor head 26 is set slightly smaller than the inner diameter of the opening 28 on the concrete structure 12, 14 side. If the tension of the PC steel wire 18 is not directly transmitted to the concrete structures 12 and 14, there is no problem, but the outer diameter of the contact portion 26b of the anchor head 26 and the concrete structure When the inner diameter of the opening 28 on the side of the body 12 or 14 substantially matches, or when the outer diameter of the contact portion 26b of the anchor head 26 is larger than the inner diameter of the opening 28, PC The tension of the steel wire 18 may be directly transmitted to the concrete structures 12 and 14. For this reason, by forming such a groove 35, the tension of the PC steel wire 18 can surely pass through the beam 40. The width of the groove 35 is appropriately set according to the outer diameter of the contact portion 26b of the anchor head 26 and the inner diameter of the opening 28.
[0028]
In addition, the surface of the inner peripheral portion 34 on the anchor head 26 side has a shape slightly protruding toward the anchor head side from the surface of the outer peripheral portion 38. On the other hand, the surface of the inner peripheral portion 34 on the side of the concrete structures 12 and 14 is formed to be slightly outward (upper in FIG. 5) from the surface of the concrete structures 12 and 14 (support plate 39). By adopting such a shape, in addition to the effect of providing the groove 35, the tension of the PC steel wire 18 can more reliably pass through the beam 40.
[0029]
Further, in the load cell 30 formed in this manner, the strain member 31 has a half-split structure. This is because the load cell 30 is disposed so as to surround the PC steel wire 18 from the outside, and thus the strain member 31 is constituted by the two semicircular divided pieces. The load cell 30 can be interposed between the anchor head 26 and the concrete structures 12 and 14 in a state where the anchor head 26 is attached to the end portion 18a. Thereby, the work of attaching or removing the load cell 30 can be easily performed.
[0030]
Also, as shown in FIGS. 6 and 7, No. 1 to No. No. 12 is attached, and the No. 1 to No. The strain gauges 42 attached to the respective holes 36 up to No. 12 are described with reference numerals 1a, 1b to 12a, 12b. One bridge circuit 43 is constituted by the strain gauges 42 (1a, 1b, 2a, 2b) of a total of four elements attached to the through holes 36 of 1 and 2. In this illustrated example, the No. Nos. 3 and 4, No. The bridge circuits 43 are formed as a set of the strain gauges 42 of the four elements between the adjacent through-hole portions 36, such as 5 and 6, and a bridge circuit 43 of six systems is configured in total. The combination of the twelve through-hole portions 36 does not necessarily have to be adjacent to each other, and may be an arbitrary combination.
[0031]
The input / output signal lines from the bridge circuits 43 of each system are bundled together and formed as an input / output cable 54, and a total of six input / output cables 54 are drawn out of the load cell 30. That is, the detection signal from the bridge circuit 43 of each system is extended from the distortion member 31 and penetrates the rust preventive material (such as grease) 52 to the outside of the end cap 50 as shown in FIGS. Are output through six input / output cables 54, which are connected to the respective channels of the strain measuring device 55a having the first to sixth channels. Is connected to a computer device 55b or the like, so that the external force based on the detection result of the strain gauge 42, that is, the tension of the PC steel wire 18 can be monitored at any time. In other words, the measurement is equivalent to the presence of six load cells, and the portions where the bridge circuits 43 of each system are attached are treated as independent measurement points. Therefore, even if one of the 24 strain gauges 42 fails, only the bridge circuit 43 of the system in which the strain gauge 42 is incorporated cannot be measured, and the other sound bridge circuits 43 can measure. is there.
[0032]
In the load cell 30, six systems of the bridge circuit 43 are configured by using four elements of the strain gauge 42. Nos. 1 to 6 and Nos. A total of two bridge circuits may be configured by the strain gauges 42 each having 12 elements attached to 7 to 12, and the total number of strain gauges, the combination thereof, the number of systems, and the like can be determined as appropriate.
[0033]
Then, as described above, the anchor head 26 provided integrally with the end 18a of the PC steel wire 18 inserted therein to apply prestress to the concrete structures 12, 14, and the concrete structure 12 , 14, the tension of the PC steel wire 18 can be monitored at any time. To check the tension, the PC steel wire 18 is re-tensioned as usual. There is no need for such work. For this reason, it is sufficient to apply the tension only when the tension is insufficient, so that the periodic inspection can be greatly simplified. In addition, in the load cell 30, since the tension of the PC steel wire 18 is detected as a shear strain and the measurement is performed by the strain gauge 42, the measurement can be performed with very high accuracy. Can be improved.
[0034]
Next, a method of applying the fixing structure will be described. FIG. 8 shows a procedure when the fixing structure according to the present invention is installed in place of the conventional fixing structure.
[0035]
First, as shown in FIG. 8A, a lift-off jack 60 is attached to the end 18a of the PC steel wire 18 protruding from the anchor head 26, and the end of the PC steel wire is gripped. The lift-off jack 60 is fixed to the concrete structures 12, 14 via a jack chair 62. Using this jack chair 62, the end 18a of each PC steel wire 18 is pulled. Next, with the end 18a of the PC steel wire 18 being pulled by the lift-off jack 60, the shim 64 is removed as shown in FIG. Then, as shown in FIG. 8C, the aforementioned load cell 30 is mounted in place of the removed shim 64. Here, as described above, the load cell 30 has a half-split structure, and is divided into two semicircular divided pieces. Thereby, at the time of attachment or removal, it can be attached to the outside of the PC steel wire 18 by being divided into two divided pieces, and can be removed from the portion. Then, as shown in FIG. 8D, the lift-off jack 60 is removed, the end cap 50 is mounted, and the inside is filled with the rust preventive material 52, thereby completing the operation.
[0036]
Next, a construction method when the fixing structure is newly provided will be described. FIG. 9 is for explaining the construction method. When a prestressed concrete containment vessel or the like is newly constructed, a fixing structure for the PC steel wire 18 will be newly provided. In this case, when tension is applied to the PC steel wire 18, a load cell 30 can be interposed between the anchor head 26 and the concrete structures 12, 14. Then, after the load cell 30 is interposed, as shown in FIG. 9, a tension jack 70 is set at the end of the PC steel wire 18 protruding from the anchor head 26, and the end 18a of the PC steel wire 18 is tensioned to the tension jack 70. With the load cell 30 sandwiched between the anchor head 26 and the concrete structures 12 and 14, the end 18 a of the PC steel wire 18 is gradually pulled by the tension jack 70, and the tension is applied to the PC steel wire 18. Introduce the power.
[0037]
In the above embodiment, the case where the external force measuring device according to the present invention is incorporated in the fixing structure of the tension wire of the nuclear containment vessel to measure the tension of the tension wire such as the PC steel wire has been described. However, the present invention is not limited to such a case, and can be suitably applied to, for example, the measurement of the tension of a tension wire of a suspension structure of a bridge and the measurement of the tension of a ground anchor such as a slope or a retaining wall. In addition to the measurement of the tension of the tension wire, the present invention can be easily applied to a member to which a compressive force is applied, and the compressive force can be measured as an external force.
[0038]
Further, in the present embodiment, the distortion member 31 has a half-split structure composed of two divided pieces. However, the present invention is not limited to such a case, and is configured by three or more divided pieces. It does not matter.
[0039]
Next, a process performed by the measuring device 55 including the distortion measuring device 55a and the computer device 55b upon receiving the output signal from the bridge circuit 43 of each system will be described.
[0040]
That is, the strain measuring device 55a and the computer device 55b calculate the external force value for each of a plurality of channels to which the bridge circuits 43 of each system are connected, here, the first to sixth channels, and calculate the calculated first to sixth channels. The average value of the external force values of the six channels is calculated and output as a measured value. Further, the measuring device 55 determines, based on the output measurement value and the external force value calculated for each bridge circuit 43, what ratio the external force value for each bridge circuit 43 has to the above measurement value. The calculated ratio (hereinafter, this ratio is referred to as a sharing ratio) is stored as the sharing ratio of each bridge circuit 43.
[0041]
That is, the measuring device 55 receives the outputs from the bridge circuits 43 of the respective systems, performs measurement processing on each of them independently, obtains an average value thereof, and uses the average value as an output detected by the load cell 30. When a bridge circuit in one of the six systems fails, the average value of the remaining healthy systems is regarded as the measurement value of the load cell 30 and output. Hereinafter, a measurement method in which the average value of the calculated values calculated from the signals detected by the multi-system bridge circuits 43 is used as a measurement value is referred to as a multi-system measurement method.
[0042]
By the way, in this multi-system measurement method, when the measurement accuracy is to be maintained at a high level, it is considered that the bridge circuits 43 of the respective systems do not output the same for all loads, and that there is a mutual variation. There is a need. This variation is caused by the fact that the various conditions (the shape of the through-hole portion 36 and the beam portion 40, the manner in which the load is applied, the sensitivity of each strain gauge 42, and the like) for each system are not the same, and there is mutual variation. Is what you do. Therefore, when the element of the strain gauge 42 constituting the bridge circuit 43 of a certain system fails and cannot be measured, the calculated values of the remaining measurable systems are simply removed except for the bridge circuit of the relevant system. If an average value is taken, there is a concern that in the case where an extremely high-precision measurement value is required, the error becomes a nonnegligible magnitude.
[0043]
Therefore, when an extremely high-precision measurement value is required as described above, an average is taken in consideration of a difference in output of each system. Specifically, the value calculated by the bridge circuit 43 for each system when the measurement was normally performed in all the systems is divided by a measurement value (output measurement value from the measuring device) obtained by simply averaging them. (That is, the above share ratio). In other words, a system whose calculated value is larger than the measured value (average value) has a sharing ratio larger than 1, and conversely, a smaller system has a smaller sharing ratio. Then, a value obtained by dividing the calculated value of each system by the sharing ratio of the system is equal to the average output (measurement device output). This means that the measured value to be output from the measuring device 55 can be obtained without using all the calculated values of the bridge circuits of all the systems if the sharing ratio is accurately known. That is, even if there is a part of the system that cannot be measured, the output of the bridge circuit of each system can be known from the value obtained by dividing the output of the remaining system by the sharing ratio of that system.
[0044]
However, the fact that some systems cannot be measured means that the share at that time cannot be determined. Therefore, the assignment ratio of each system is obtained from data immediately before a certain system cannot be measured (when all the systems are healthy) and stored in advance, and using the assignment ratio, the bridge circuit output of the healthy system is output. The output measurement value from the measuring device 55 is obtained based on As a specific method, the external force value of each system calculated based on the bridge circuit output of the sound system is divided by the respective sharing ratios stored when all the previous systems were sound, Further, an average of the divided values is taken as an output measured value of the measuring device 55. It is preferable that the above-mentioned sharing ratio be constantly calculated and updated as described above in order to maintain the measurement value when an unmeasurable system occurs with extremely high accuracy. Instead, the initial sharing ratio may be calculated and stored by a separate means, and the initial sharing ratio may be used. In this case, the initial sharing ratio is sufficiently higher than the measured data of the simple average. Accurate measurement value data can be obtained.
[0045]
A value obtained by multiplying the output measurement value by a calibration coefficient is defined as a load. The calibration coefficient is a coefficient between the output of the measuring instrument and the load at that time, and is 1 × 10^-6Expressed as the load value per hit. The value is obtained in advance as a unique value of the load cell at the time of shipment of the load cell by a calibration operation using a force reference machine. In this load cell, 0.001694MN / 1 × 10^-6The result has been obtained.
[0046]
This can be expressed as follows.
(Equation 1)

[0047]
Next, the durability of the load cell 30 configured as described above and the operation and effect of the multi-system measurement method will be described.
<1> Load cell durability
The strain gauge type load cell 30 has essentially no long-term stability because it has no mechanically movable parts. In particular, when used for PCCV tendon tension measurement as in the present embodiment, the load cell 30 is installed in an end cap that is shielded from the outside air, and is filled with grease. The working volume is fixed at approximately 80% of the capacity. These environmental conditions are extremely favorable for the load cell 30, and the service life of the load cell 30 is very long.
[0048]
Here, when the load cell 30 is further divided into its constituent elements and its durability is considered, the following is obtained.
1) About strain members
The strain member 31 is a portion that undergoes elastic deformation under load, but since it has a structure integrated with metal and the applied load is constant at approximately 80% of the capacity, no failure occurs. Conceivable.
[0049]
2) About strain gauges, adhesives, coating materials, and connections
The strain gauge 42 is a part that electrically detects elastic deformation generated in the strain member 31. It is made of metal, resin, or the like. If a failure occurs due to infiltration of moisture or the like, accurate operation cannot be performed, and the function of the load cell 30 is impaired. However, in the present embodiment, the mounting portion of the strain gauge 42 has a structure as shown in FIGS. 3 and 8, and these are not exposed to the outside air. Therefore, the probability of occurrence of a failure is very low, but by adopting the “multi-system measurement method” described later, it is possible to virtually eliminate the possibility that the load cell 30 will fail.
The strain gauge 42 is attached to the inner wall of the through hole 36. The through hole 36 is sealed by a lid and an O-ring, and is completely shut off from outside air.
[0050]
3) Input / output cable (in the end cap)
This is a portion for electrically connecting the internal circuit of the load cell 30 and the externally provided strain measuring device 55a. If a failure occurs due to mechanical damage or the like, measurement may be hindered. However, in the present embodiment, the input / output cable 54 in the end cap is left stationary in the attached state, and is covered. Therefore, if there is no failure at the time of attachment, there is no problem during the life of the plant.
[0051]
From the above, regarding the durability of the load cell 30 in the present embodiment, the strain gauge 42, the adhesive, the coating material, and the connection portion are considered. By adopting the measurement method “multi-system measurement method”, it is possible to virtually eliminate the failure as the load cell 30.
[0052]
That is, the “multi-system measurement method” in the present embodiment means that six independent bridge circuits 43 are formed into six systems, and the average value of the outputs of the six bridge circuits is usually used as a measurement value. If a bridge circuit of a certain system cannot be measured due to a failure of any of the strain gauges 42, the average value of the calculated values based on the outputs from the remaining healthy bridge circuits is obtained, and the average value is measured. Value. This makes it possible to reduce as much as possible the rate at which the failure of the strain gauge 42 leads to the failure of the load cell 30 as a whole.
[0053]
That is, even if one of the strain gauges 42 fails, the bridge circuit 43 in which the strain gauge 42 is incorporated cannot be measured, but the other bridge circuits 43 can be measured. In the multi-system measurement method, an average value of calculated values based on a plurality of bridge circuit outputs is obtained and used as a measured value. Can be obtained.
[0054]
Here, if the forces applied to the plurality of strain-generating portions of the strain member 31 are not uniform, an error will occur there. However, in general, the load applied to each strain-generating portion at the beginning of the load is large. However, since the measurement is performed under a state in which a substantially constant load is applied, the load sharing ratio of each strain generating portion does not change significantly. Therefore, if a weighted average value is calculated from the remaining calculated values based on the output of each bridge circuit, taking the load sharing ratio up to that point into account, the error can be made as small as possible, and a sufficiently effective extremely high value can be obtained. Accurate data can be obtained. Alternatively, even if a simple average is taken instead of a weighted average, practically sufficient data can be obtained with only a slight decrease in accuracy.
[0055]
On the other hand, the cause of the failure of the load cell 30 is almost entirely caused by external factors such as overload, cable damage, and intrusion of moisture. For these, even if the number of systems is increased, a reduction in the failure rate cannot always be expected. For example, if the load member is overloaded, the distortion member 31 loses its normal characteristics, so that even if there are a plurality of bridge circuits 43, all of them fail. However, in the present embodiment, a failure due to these external factors is not considered.
[0056]
That is, the load is a state where almost 80% of the capacity is always applied, and there is no overload. Further, since the load cell 30 is left standing in the attached state, the cable 54 is not damaged. Further, since the load cell 30 is mounted in the grease cap, it is almost completely shut off from the outside air. For these reasons, what is at stake in the present embodiment is a failure caused by the circuit unit such as the strain gauge 42, and for the failure of the circuit unit, it is effective to reduce the failure rate by increasing the number of systems. .
[0057]
As for the cost of the load cell 30 itself due to the multi-system, the cost increase is not so large unless the shape of the strain generating portion or the number of strain gauges is changed.
[0058]
<2> Failure rate in multi-system measurement method
(1) Probability that all systems will fail
Here, the failure of the load cell 30 is caused only by the failure of the strain gauge 42, and the effect of the failure rate of the strain gauge 42 on the failure rate of the load cell 30 is considered. However, the failure of the strain gauge 42 is an independent event, and the failure of the load cell 30 is when the bridge circuits of all systems cannot be measured.
[0059]
Here, assuming that the probability of failure of one strain gauge during a certain period is α, the number of bridge circuit systems is m, and the number of strain gauges (number of elements) is n (n / 4m: an integer), the strain gauge The probability β that the load cell will fail due to the failure of
(Equation 2)

It becomes.
[0060]
Assuming that the number (number of elements) n of the strain gauges 42 is 24, the number m of possible bridge systems is m = 1, 2, 3, 6. However, since the load cell is a half-split type, m = 3 is excluded in consideration of manufacturing problems.
[0061]
It is very difficult to estimate the failure rate α of a strain gauge, but if it is assumed that 3% of failures will occur in 60 years, β at m = 1, 2, 6 is given by the following equation (1).
(Equation 3)

It becomes.
[0062]
Therefore, the failure rate of 2 systems and 6 systems for 1 bridge system is respectively
(Equation 4)

It becomes.
[0063]
In other words, the failure rate is reduced to about one-fifth by using two systems, and to about one in 200,000 by using six systems. This means that, if the number of systems is increased, the measurement cannot be performed even if the accuracy is slightly reduced unless all the systems fail, so that the failure rate can be significantly reduced as a result. Although the failure rate β of the load cell 30 is determined by the failure rate α of the strain gauge 42, the probability of failure of the strain gauge 42 itself regardless of external factors is 3% in 60 years. Probably.
[0064]
(2) Probability that some systems will fail
If there are six systems, the probability of failure of all systems is almost zero, but the probability of failure of some systems is as follows.
[0065]
Α is the probability of failure of one strain gauge in a certain period, m is the number of bridge systems, n is the number of strain gauges (number of elements) (where n / 4m is an integer), and one bridge circuit 43 fails. If the probability is γ,
(Equation 5)

[0066]
It becomes.
[0067]
Here, assuming that the probability that the bridge circuit 43 of the p-system out of the m-systems fails is δ,
(Equation 6)

[0068]
It becomes.
[0069]
However, here
(Equation 7)

[0070]
It is.
[0071]
When δ is obtained at p = 0, 1, 2, 3, 4, 5, and 6 assuming that m = 6, n = 24, and α = 0.03,
δ_{p = 0}= ｛1- (1-0.03)^24/6｝⁰(1-0.03)^{24 (6-0) / 6}×₆C₀= 0.48
δ_{p = 1}= ｛1- (1-0.03)^24/6｝¹(1-0.03)^{24 (6-1) / 6}×₆C₁= 0.37
δ_{p = 2}= ｛1- (1-0.03)^24/6｝²(1-0.03)^{24 (6-2) / 6}×₆C₂= 0.12
δ_{p = 3}= ｛1- (1-0.03)^24/6｝³(1-0.03)^{24 (6-3) / 6}×₆C₃= 2.1 × 10^-2
δ_{p = 4}= ｛1- (1-0.03)^24/6｝⁴(1-0.03)^{24 (6-4) / 6}×₆C₄= 2.0 × 10^-3
δ_{p = 5}= ｛1- (1-0.03)^24/6｝⁵(1-0.03)^{24 (6-5) / 6}×₆C₅= 1.1 × 10^-4
δ_{p = 6}= ｛1- (1-0.03)^24/6｝⁶(1-0.03)^{24 (6-6) / 6}×₆C₆= 2.3 × 10^-6
It becomes.
[0072]
As described above, the probability that all systems will not fail is about 48%, the probability that only one system will fail is about 37%, the probability that two systems will fail is about 12%, and the probability that three systems will fail is about 2%. , These four cases add up to about 99%. That is, three or more systems can be measured with a probability of about 99%. On the other hand, the probability of failure of all six systems is 1 / 500,000 or less, and it can be said that there is virtually no failure. As described above, the failure rate can be extremely reduced by employing the multi-system measurement method.
[0073]
【The invention's effect】
As described above in detail, the strain gauge type external force measuring device and the measuring method according to the present invention have the following special effects.
[0074]
(1) A strain gauge is attached to a strain member that is elastically deformed by an external force to form a plurality of bridge circuits, and each of the bridge circuits is connected to a plurality of channels of a measuring instrument to individually calculate an external force value. However, since the average value of these calculated values is calculated and used as the measured value, even if any of the strain gauges fails, the bridge circuit in which the strain gauge is incorporated cannot be measured, and at least one of the strain gauges cannot be measured. If only one bridge circuit can be measured, the external force can be measured by the sound bridge circuit, and the probability that the strain gauge type external force measuring device cannot be measured can be reduced as much as possible. Performance can be greatly improved.
[0075]
(2) Since the average value of the calculated values based on the outputs of the plurality of bridge circuits is obtained and used as the measured value, the average value is caused by the variation in the shape of the strain generating portion of the strain member, the sensitivity of the strain gauge, the uneven distribution of the load, and the like. The error can be made as small as possible, and a highly accurate and highly reliable measurement value can be obtained.
[0076]
(3) In addition, the ratio between the measured value and the external force value for each bridge circuit is stored as a share ratio, and when there is a failed bridge circuit, the calculated value of another healthy bridge circuit is shared. By calculating the average value of the values divided by the ratio and outputting the average value as the measurement value, it is possible to increase the measurement error even if a system that cannot be measured occurs. This makes it possible to obtain highly accurate measured values with high reliability.
[0077]
(4) A strain member is interposed between the locking member provided at the end of the tensioning wire and the fixing target portion to transmit the tension from the tensioning wire to the fixing target portion and to reduce the tension. By generating the corresponding shear strain in the strain member, detecting the amount of shear strain of the strain member with a strain gauge and measuring the tension of the tension wire, the tension can be measured whenever necessary. If the present invention is applied to the tension measurement of the tension wire of the reactor containment vessel, the periodic tension measurement work can be extremely easily completed.
[0078]
(5) An inner peripheral portion abutting on the locking member and receiving the tension of the tension wire, and an outer peripheral portion abutting on the fixing target portion side and transmitting the tension to the fixing target portion side And a beam portion provided between the inner peripheral portion and the outer peripheral portion so as to be connected therebetween, where the shear strain is generated, and an insertion hole portion provided in the inner peripheral portion and through which the tension wire is inserted. By constituting the strain member, a shear strain corresponding to the tension of the tension wire can be generated in the beam portion, and by providing the strain gauge in the beam portion, the tension of the tension wire can be accurately and easily adjusted. Can be detected.
[0079]
(6) By configuring the distortion member with a plurality of divided pieces, removal work and attachment work between the locking member and the fixing target portion can be easily performed.
[Brief description of the drawings]
FIG. 1 is an overall perspective view showing an external appearance of a prestressed concrete reactor containment vessel (PCCV) in which an external force measuring device according to the present invention is interposed at a fixing portion of a tension wire.
FIG. 2 is a partial cross-sectional perspective view showing a cross-sectional structure of an outer wall portion of the prestressed concrete containment vessel shown in FIG.
FIG. 3 is a cross-sectional view showing one embodiment of a tension wire fixing unit to which the external force measuring device according to the present invention is attached.
FIG. 4 is a plan view showing one embodiment of a load cell of the external force measuring device according to the present invention, which is attached to a fixing portion of a tension wire.
FIG. 5 is a sectional view showing an embodiment of a load cell of the external force measuring device according to the present invention, which is attached to a fixing portion of a tension wire.
FIG. 6 is a diagram illustrating 24 strain gauges attached to a strain generating portion of the load cell of FIG. 5;
FIG. 7 is a circuit diagram showing combinations of elements of 24 strain gauges formed in six independent bridge circuits.
FIG. 8 is an explanatory diagram showing a construction procedure in the case where the external force measuring device according to the present invention is replaced with an existing fixing unit and constructed.
FIG. 9 is an explanatory diagram for explaining a construction method in a case where the external force measuring device according to the present invention is provided in a fixing portion of a newly installed tension wire.
FIG. 10 is a sectional view showing a schematic configuration of a load cell.
FIG. 11 is a diagram showing a basic bridge circuit formed by four conventional strain gauges.
FIG. 12 is a diagram showing a case where one bridge circuit is formed by 24 element strain gauges.
[Explanation of symbols]
10 containment vessel
12cm lower concrete structure
14 Upper concrete structure
16 rebar
18 PC steel wire (tension wire)
20 sheath tube
26mm anchor head (locking member)
30 load cell
31 ° distortion member
32mm insertion hole
34 inner circumference
36mm through hole
38mm outer circumference
39 support plate
40mm beam
42 strain gauge
43 bridge circuit
50mm end cap
52 rust prevention material
55 ° measuring instrument
55a strain measuring instrument
55b computer equipment

Claims (7)

A strain member to which an external force is elastically deformed, a strain gauge attached to the strain member to form a bridge circuit, and a measuring device for calculating an external force applied to the strain member based on an output of the bridge circuit. An external force measuring device comprising:
At least two or more bridge circuits are independently formed, and the measuring device has a plurality of channels to which each bridge circuit is individually connected, calculates an external force value for each of the plurality of channels, and A strain gauge type external force measuring device, which calculates an average of external force values and outputs the average value as a measured value. The measuring device stores the ratio of the external force value of each bridge circuit to the measured value as a sharing ratio, and when there is a faulty bridge circuit, calculates the calculated value of each other healthy bridge circuit as the sharing ratio. A strain gauge type external force measuring device, wherein an average value of the values divided by (1) is calculated and the average value is output as a measured value. The strain member is interposed between a locking member provided at an end of the tension wire to which tension is applied and a fixing target portion fixing the end of the tension wire, and the tension of the tension wire is adjusted. The strain gauge type external force measuring device according to claim 1, wherein the external force is measured. The distortion member is in contact with the locking member and receives the tension of the tension wire, and is in contact with the fixing target portion side to transmit the tension to the fixing target portion side. An outer peripheral portion, a beam portion which is provided by connecting between the inner peripheral portion and the outer peripheral portion and in which the shear strain is generated, and an insertion hole provided in the inner peripheral portion and through which the tension wire is inserted. The strain gauge type external force measuring device according to claim 3, wherein the strain gauge is provided on the beam portion. The strain gauge type external force measuring device according to claim 4, wherein the strain member is constituted by a plurality of divided pieces. A strain gauge that forms a bridge circuit is attached to a strain member that is elastically deformed by the application of an external force, and the external force applied to the strain member is calculated by a measuring device based on the output of the bridge circuit. In the method,
An external force measuring method comprising: providing a plurality of bridge circuits; calculating an external force for each bridge circuit; and using an average value of the calculated values as a measured value. The ratio of the external force value of each bridge circuit to the measured value is stored as a share ratio, and if there is a failed bridge circuit, the calculated value of another healthy bridge circuit is divided by the share ratio, and The external force measuring method according to claim 6, wherein an average value of the divided values is used as a measured value.

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