Specific Research Reports of the National Institute of Occupational Safety and Health, JNIOSH-SRR-No.37 (2008) UDC 624.2/.8:679.748 5. ワイヤグリップの使用基準に関する検討 佐々木哲也 *, 本田尚 *, 山際謙太 * 5. Investigation of Wire Rope Grip Usage Standard by Tetsuya SASAKI*, Takashi HONDA*, Kenta YAMAGIWA* Abstract; The cable erection method is used in the construction of steel bridge. Even though this method is very versatile and used only as a last resort to build an arch-type bridge over a deep valley, the nature of the method requires the use of many wire ropes and each one must be terminated using wire rope grips. One of the major problems with this method is the risk of wire rope slipping through the wire rope grips in the case of improper fitting. All grips are installed according to the wire rope grip usage standard; nevertheless, accidents due to wire rope slipping through the grips frequently occurs at bridge construction sites employing the cable erection method. This fact suggests that the existing usage standard for wire rope grips may be insufficient. To clarify this problem, an intensive study was carried out to reveal the adequacy of the current usage standard for U-bolted wire rope grips. Since the efficiency of termination using U-bolted wire rope grips depends on many factors including the type and diameter of the wire rope, number of grips, tightening torque, etc., the wire rope types mainly used for the cable erection method were firstly determined through a survey of bridge construction companies. According to the survey, fiber core (FC) 6x24 and 6x37 type wire ropes are mainly used for small-diameter wire ropes less than 22.4mm, and IWRC 6xFi(25) and FC 6x37 types for large-diameter wire ropes over 22.4mm. Based on this result, loading tests were conducted to reveal the effect of several factors on the efficiency of wire grip termination. The main conclusions from this study are as follows: (1) For large-diameter wire ropes over 16mm, the current standard for U-bolted wire grips cannot provide sufficient efficiency of termination. (2) Repeatedly used wire grips may lead to decreased efficiency of termination. (3) M-type grips fitted under the manufacturer s standard exhibit sufficient efficiency of termination. Keywords; Wire Rope Grip, Wire Rope, Cable Erection Method, Tightening Torque, U-bolted Wire Rope Grip, Wire Rope Grip Usage Standard * Mechanical and System Safety Research Group 41
労働安全衛生総合研究所特別研究報告 JNIOSH-SRR-No.37(2008) 1. 緒言 4 12 4 9 8 10 11 JIS B 2809 1) U U 2) JIS B 2809-1996 IWRC U M 2. 予備的検討 2.1 ワイヤグリップの保持力に影響を及ぼす因子 U Fig.1 Factors considered to be affecting the efficiency of the wire grip termination. ワイヤグリップ止めの効率に影響を及ぼすと考えられる因子 Fig.1 2.2 ケーブルエレクション工法で使用されるワイヤロープ形式の調査 26 16 Table 1 10~22.4mm FC 6 24 6 37 70% IWRC24~40mm 44~60mmIWRC IWRC 6 Fi 25 1/4 22.4mm 24mm 6 37 6 24 6 37 IWRC 6 Fi 25 3. 小径ワイヤロープのグリップ保持力特性に関する実験的検討 3.1 実験方法 22.4mm 42
ワイヤグリップの使用基準に関する検討 Table 1 Percentage of the wire rope type used in the cable erection method. ケーブルエレクション工法で使用されるワイヤロープ形式の割合 Fig.2 Test piece for the wire grip loading test. ワイヤグリップ保持力試験供試体 Fig.2 Photo.1 2 3 2 2 3mm 3) 90% JIS B 2809 U F JIS G 3525 6 37 6 24 6 37 12.6mm 16mm 22.4mm 3 Table 2 6 24 6 37 2) 20% 2 3) 10% JIS B 2809 15~20% 20% Photo.1 Wire grip loading test for small diameter ropes. 小径ロープのグリップ保持力実験の様子 Table 2 Wire grip installation standard for type 6 24 /6 37 wire ropes by Transmission Line Construction Engineering Society. 送電線建設技術研究会による 6 24/6 37 ワイヤロープに対するグリップ取付け基準 3.2 6 37ワイヤロープの実験結果 Fig.3 5 3P 4P w/ extra tightening, w/o extra tightening 43
労働安全衛生総合研究所特別研究報告 JNIOSH-SRR-No.37(2008) U 80% 80% 3.2.1 直径 12.6mmワイヤの実験結果 1 3 80% 4 16N m 80% 3.2.2 直径 16mmワイヤの実験結果 1 3 80% 4 37N m 80% 3.2.3 直径 22.4mmワイヤの実験結果 1/3 80% 2 7 108N m 6 80% 6 19 7100N m Fig.4 Result for type 6 37,φ16mm wire ropes. 6 37,φ16mm ワイヤの実験結果 Fig.3 Result for type 6 37, φ12.6mm wire ropes. 6 37,φ12.6mm ワイヤの実験結果 Fig.5 Result for type 6 37, φ22.4mm wire ropes. 6 37,φ22.4mm ワイヤの実験結果 44
ワイヤグリップの使用基準に関する検討 3.3 6 24 ワイヤロープの実験結果 Fig.6 8 6 24 6 37 3.3.1 直径 12.6mmワイヤの実験結果 16N m 80% 3.3.2 直径 16mmワイヤの実験結果 37N m 3.3.3 直径 22.4mmワイヤの実験結果 2/3 2 7 80% 108N m 7 75% 80% 6 19 7100N m 3.4 ワイヤグリップ間隔の影響 Fig.7 Result for type 6 24, φ16mm wire ropes. 6 24,φ16mm ワイヤの実験結果 Fig.6 Result for type 6 24, φ12.6mm wire ropes. 6 24,φ12.6mm ワイヤの実験結果 Fig.8 Result for type 6 24, φ22.4mm wire ropes. 6 24,φ22.4mm ワイヤの実験結果 45
労働安全衛生総合研究所特別研究報告 JNIOSH-SRR-No.37(2008) 6 37 Table 3 S 1.5 Table 3 Effect of wire grip interval on efficiency of termination. ワイヤグリップ間隔の効率への影響 3.5 シンブルとシーブの違いによる影響 6 37 20% Table 4 12.6 16 mm 80% 22.4mm 80% 50% 22.4mm 12.6mm 16mm 80% 4. 中径 太径ワイヤロープのグリップ保持力特性に関する実験的検討 4.1 実験方法 24mm Fig.9 Table 4 Effect of the difference between thimble and sheave on efficiency of termination. シンブルとシーブの違いによる効率への影響 JIS B 2809 U F JIS G 3525 6 37 IWRC 6 Fi 2528mm 38mm 50mm 60mm 4 46
ワイヤグリップの使用基準に関する検討 Table 5 6 19 2) 1 6 37 22.4mm 6 3780% 5 85% 1 2 20% Photo.2 4.2 実験結果 Fig.10, 11 6 37IWRC 6 Fi 25 Fig10, 11 2 3 3mm 0mm 6 37 6 19 2) 4.2.1 繊維心 6 37ワイヤの実験結果 28mm~60mm 6 37 85% 3mm 6 19 1 38mm 85%3mm 80% 6% 6 19 80% 4.2.2 IWRC 6 Fi(25) ワイヤの実験結果 6 37 28mm~60mm 6 37 85% 3mm 6 19 2 85% 3mm 6 19 1 Fig.9 Illustration of wire grip loading test for medium & large-diameter ropes. 中径 太径ワイヤロープによるワイヤグリップ保持力試験の概念図 Table 5 Wire grip installation standard for type 6 19 wire ropes by Transmission Line Construction Engineering Society. 送電線建設技術研究会による6 19ワイヤロー 1) プに対するグリップ取付け基準 Photo.2 Wire grip loading test for large-diameter ropes. 太径ロープのグリップ保持力実験の様子 80% 4.2.3 経年グリップの保持力特性 47
労働安全衛生総合研究所特別研究報告 JNIOSH-SRR-No.37(2008) 4) 28mm 6 3720% 2 Table 685% 3mm 0mm 1 5. M 型グリップの保持力特性 Fig.10 Experimental result for FC 6 37 type ropes. 繊維心 6 37 ワイヤの実験結果 U M 5) 4 M JIS G 3525 6 37 28mm 50mmM 12 2 M M U 1 M 20% 2 M Photo.3 85% 0mmM Fig.11 Experimental result for IWRC 6 Fi(25)type ropes. IWRC 6 Fi(25) ワイヤの実験結果 48
ワイヤグリップの使用基準に関する検討 Table 6 Difference between new grips and repeatedly used grips. 新品グリップと経年グリップに必要グリップ数の違い 6. 結論 1 22.4mm 6 24 6 3722.4mm 6 37 IWRC 6 Fi 25 6 Fi 29 26 24 6 37 12.4mm 16mm U 6 24~6 37 80% 22.4mm 80% 6 37 6 19 6 24 3 6 37 24~60mm U 80% 6 19 4IWRC 6 Fi 25 24~60mm U 80% 6 19 1 5 6 Photo.3 Wire grip loading test using M- type grips. M 型グリップの保持力実験風景 7 8 M 28,50mm6 37 80% 謝辞 参考文献 1, JIS B2809,,, 1996. 2,, 1992. 3,,, 1976. 4,, 20, pp.968-969, 1993 5,,, Vol.4, pp.83-89, 2000. 21 15 49