Mobile QR Code QR CODE : Journal of the Korean Society of Civil Engineers

  1. ์„œ์šธ๋Œ€ํ•™๊ต ๊ฑด์„คํ™˜๊ฒฝ๊ณตํ•™๋ถ€ ์„์‚ฌ๊ณผ์ • (Seoul National Universityโ€คhyune7037@snu.ac.kr)
  2. ์ •ํšŒ์›โ€ค์„œ์šธ๋Œ€ํ•™๊ต ๊ฑด์„คํ™˜๊ฒฝ๊ณตํ•™๋ถ€ ๋ฐ•์‚ฌ๊ณผ์ • (Seoul National Universityโ€คpeacefulan@snu.ac.kr)
  3. ์ข…์‹ ํšŒ์›โ€คํ•œ๋‚จ๋Œ€ํ•™๊ต ํ† ๋ชฉํ™˜๊ฒฝ๊ณตํ•™์ „๊ณต ์กฐ๊ต์ˆ˜ (Hannam Universityโ€คycpark@hnu.kr)
  4. ์ข…์‹ ํšŒ์›โ€ค๊ต์‹ ์ €์žโ€ค์„œ์šธ๋Œ€ํ•™๊ต ๊ฑด์„คํ™˜๊ฒฝ๊ณตํ•™๋ถ€ ํฌ์Šค์ฝ”์„์ขŒ๊ต์ˆ˜ (Corresponding Authorโ€คSeoul National Universityโ€คhokyungk@snu.ac.kr)



ํ”ผ๋กœ์‹ ๋ขฐ๋„ํ‰๊ฐ€, ํ˜„์žฅ๊ณ„์ธก๋ฐ์ดํ„ฐ, ๋ณ€ํ˜•๋ฅ ๊ณ„์ธก, BWIM, ์œ ํ•œ์š”์†Œํ•ด์„
Fatigue reliability evaluation, Field measurement data, Strain measurement, BWIM, Finite element analysis

1. ์„œ ๋ก 

๊ต๋Ÿ‰์€ ๊ณต์šฉ์—ฐ์ˆ˜๊ฐ€ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ, ์ฐจ๋Ÿ‰ ํ†ตํ–‰ ์‹œ ๊ต๋Ÿ‰ ๋ถ€์žฌ์— ๋ฐœ์ƒํ•˜๋Š” ๋ฐ˜๋ณต์ ์ธ ์‘๋ ฅ์— ์˜ํ•ด ํ”ผ๋กœ ์†์ƒ์ด ์ง€์†ํ•ด์„œ ๋ˆ„์ ๋œ๋‹ค. ๋ฐ˜๋ณต์‘๋ ฅ์— ์˜ํ•ด ๋ˆ„์ ๋œ ํ”ผ๋กœ ์†์ƒ์€ ๋ถ€์žฌ์— ํ”ผ๋กœ ๊ท ์—ด์„ ์œ ๋ฐœํ•˜๊ณ  ํ”ผ๋กœ ํŒŒ๊ดด๋ฅผ ๋ฐœ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค(Nyman and Moses, 1985). ๋”ฐ๋ผ์„œ, ์ฐจ๋Ÿ‰ ํ•˜์ค‘์— ์˜ํ•ด ๊ต๋Ÿ‰ ๋ถ€์žฌ์— ํ”ผ๋กœ ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜๋Š” ๊ฒƒ์„ ๋ฐฉ์ง€ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ๋ˆ„์ ๋œ ํ”ผ๋กœ ์†์ƒ์„ ์ •๋Ÿ‰์ ์œผ๋กœ ํ‰๊ฐ€ํ•ด์•ผ ํ•œ๋‹ค. ๊ต๋Ÿ‰ ํ”ผ๋กœ ์ƒ์„ธ์— ์ž‘์šฉํ•˜๋Š” ๋ฐ˜๋ณต์‘๋ ฅ ๋ฒ”์œ„ ๋ฐ ํšŸ์ˆ˜์˜ ์ถ”์ •์€ ํ”ผ๋กœ ํ‰๊ฐ€์— ์žˆ์–ด ๊ฐ€์žฅ ์ค‘์š”ํ•œ ์ž‘์—…์ด๋ฉฐ, ๋ณ€ํ˜•๋ฅ ๊ณ„ ๋ฐ Bridge Weigh-In-Motion (BWIM) ์‹œ์Šคํ…œ๊ณผ ๊ฐ™์€ ํ˜„์žฅ๊ณ„์ธก์œผ๋กœ๋ถ€ํ„ฐ ์ด๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค.

๋ณ€ํ˜•๋ฅ  ๊ณ„์ธก ์ •๋ณด๋ฅผ ํ™œ์šฉํ•œ ํ”ผ๋กœ ํ‰๊ฐ€๋Š” ํ”ผ๋กœ ์ƒ์„ธ์— ๋ฐœ์ƒํ•˜๋Š” ์‘๋ ฅ์„ ์ง์ ‘ ๊ณ„์ธกํ•˜๊ธฐ ๋•Œ๋ฌธ์—, ๊ฐ€์žฅ ์ •ํ™•ํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ฐ„์ฃผ๋œ๋‹ค(AASHTO, 2018). Minerโ€™s rule (Miner, 1945)์— ๋”ฐ๋ผ ๋ณ€ํ˜•๋ฅ  ๊ณ„์ธก ์‘๋ ฅ์œผ๋กœ๋ถ€ํ„ฐ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„ ๋ฐ ๋ฐ˜๋ณต์‘๋ ฅ ํšŸ์ˆ˜๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค. ๋ณ€ํ˜•๋ฅ  ๊ณ„์ธก ๋ฐ์ดํ„ฐ๋ฅผ ํ™œ์šฉํ•œ ์‹ ๋ขฐ๋„ ๊ธฐ๋ฐ˜์˜ ํ”ผ๋กœ ํ‰๊ฐ€์— ๊ด€ํ•ด ๋งŽ์€ ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์—ˆ๋‹ค. Frangopol et al.(2008)์€ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ์‹œ ํ˜„์žฅ๊ณ„์ธก์˜ ๋ถˆํ™•์‹ค์„ฑ์„ ๊ณ ๋ คํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ์ œ์•ˆํ•˜์˜€๋‹ค. Kwon and Frangopol(2010)์€ ์‘๋ ฅ๋ฒ”์œ„์˜ Cut-off ๋ณ€ํ™”์— ๋”ฐ๋ฅธ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„์˜ ๋ณ€๋™์„ฑ์„ ๊ณ ๋ คํ•˜์˜€๋‹ค. Deng et al.(2018)์€ ์žฅ๊ธฐ ๊ณ„์ธก๋œ ์‘๋ ฅ๋ฒ”์œ„์˜ ์ผ์ผ ๋ณ€๋™์„ฑ์„ ๊ณ ๋ คํ•˜์˜€๋‹ค. Mao et al.(2019)์€ ์žฅ๊ธฐ ๊ณ„์ธก๋œ ๋ณ€ํ˜•๋ฅ  ๋ฐ์ดํ„ฐ๋กœ๋ถ€ํ„ฐ ์‘๋ ฅ๋ฒ”์œ„ ๋ฐ ๋ฐ˜๋ณตํšŸ์ˆ˜์˜ ์›”๋ณ„ ๋ณ€๋™์„ฑ์„ ๊ณ ๋ คํ•˜์˜€๋‹ค.

ํ•˜์ง€๋งŒ, ํ”ผ๋กœ ์ƒ์„ธ์— ๋ฆฌ๋ฒณ ๋˜๋Š” ์šฉ์ ‘๊ณผ ๊ฐ™์€ ๊ตฌ์กฐ์  ํ•œ๊ณ„๋กœ ์ธํ•ด ๋ณ€ํ˜•๋ฅ ๊ณ„๋ฅผ ์„ค์น˜ํ•˜๊ธฐ ์–ด๋ ค์šธ ์ˆ˜๊ฐ€ ์žˆ๊ณ , ๊ต๋Ÿ‰์˜ ๋ชจ๋“  ํ”ผ๋กœ ์ƒ์„ธ์— ๋ณ€ํ˜•๋ฅ ๊ณ„๋ฅผ ์„ค์น˜ํ•˜๋Š” ๊ฒƒ์€ ์œ ์ง€๊ด€๋ฆฌ ๋น„์šฉ ์ธก๋ฉด์—์„œ ํšจ์œจ์ ์ด์ง€ ๋ชปํ•˜๋‹ค. ์ด๋Ÿฌํ•œ ๋ฌธ์ œ์ ์„ ๋ณด์™„ํ•˜๊ธฐ ์œ„ํ•ด, ๋ณ€ํ˜•๋ฅ  ๊ณ„์ธก ๋ฐ์ดํ„ฐ ๋Œ€์‹  BWIM ๊ณ„์ธก ๋ฐ์ดํ„ฐ์™€ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์„ ํ™œ์šฉํ•˜์—ฌ ๊ณต์šฉ ์ค‘ ๊ฐ•๊ต๋Ÿ‰์˜ ํ”ผ๋กœ ์†์ƒ์„ ํ™•๋ฅ ์ ์œผ๋กœ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•œ ์—ฐ๊ตฌ๋“ค์ด ์ง„ํ–‰๋˜์—ˆ๋‹ค. ๊ณ„์ธก๋œ ์ฐจ๋Ÿ‰ ํ•˜์ค‘์— ์˜ํ•ด ํ”ผ๋กœ์ƒ์„ธ์— ๋ฐœ์ƒํ•˜๋Š” ์‘๋ ฅ์€ ํ•ด์„๋ชจ๋ธ์—์„œ ์ฃผํ–‰ ์ฐจ์„ ์„ ๋”ฐ๋ผ ์œ„์น˜ํ•˜๊ฑฐ๋‚˜(Guo et al., 2012), ๊ฐ€์žฅ ๋ถˆ๋ฆฌํ•œ ํ•˜์ค‘ ํšจ๊ณผ๋ฅผ ์œ ๋ฐœํ•˜๋„๋ก ์œ„์น˜ํ•˜์—ฌ(Liu et al., 2016; Lu et al., 2017; Lu et al., 2019) ํ‰๊ฐ€ํ•  ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ, ์ฐจ๋Ÿ‰์˜ ์†๋„์™€ ํ†ต๊ณผ ์‹œ๊ฐ„ ์ •๋ณด๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ์‹œ๊ณ„์—ด ์‘๋ ฅ ์ด๋ ฅ ํ•ด์„์„ ํ†ตํ•ด ๊ต๋Ÿ‰์— ๋™์‹œ์— ์œ„์น˜ํ•˜๋Š” ์ฐจ๋Ÿ‰ ํ•˜์ค‘์„ ๊ณ ๋ คํ•˜์—ฌ ํ‰๊ฐ€ํ•  ์ˆ˜ ์žˆ๋‹ค(Yan et al., 2017a; Yan et al., 2017b). ๊ทธ๋Ÿฌ๋‚˜ ํ‰๊ฐ€๊ทœ์ •์—๋Š” ํ˜„์žฅ๊ณ„์ธก ๋ฐ์ดํ„ฐ๋ฅผ ํ™œ์šฉํ•œ ํ”ผ๋กœ ํ‰๊ฐ€์ ˆ์ฐจ์™€ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ์— ๋Œ€ํ•ด ๊ตฌ์ฒด์ ์œผ๋กœ ์ œ์‹œํ•˜๊ณ  ์žˆ์ง€ ์•Š๊ธฐ ๋•Œ๋ฌธ์—, ๊ณ ๋ ค๋˜๋Š” BWIM ๊ณ„์ธก ์ •๋ณด์™€ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ์ด ์ˆ˜ํ–‰๋œ ์„ ํ–‰์—ฐ๊ตฌ๋งˆ๋‹ค ๋ชจ๋‘ ๋‹ค๋ฅด๋‹ค. ๋˜ํ•œ, ํ™œ์šฉ๋œ ํ˜„์žฅ๊ณ„์ธก ๋ฐ์ดํ„ฐ์˜ ์ข…๋ฅ˜, ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ, ๊ณ ๋ ค๋˜๋Š” BWIM ๊ณ„์ธก ์ •๋ณด์— ๋”ฐ๋ฅธ ํ”ผ๋กœ ํ‰๊ฐ€๊ฒฐ๊ณผ์˜ ์ฐจ์ด์— ๋Œ€ํ•ด ์ •๋Ÿ‰์ ์œผ๋กœ ๋น„๊ตํ•œ ์—ฐ๊ตฌ๋Š” ์•„์ง ๋ฏธํกํ•œ ์‹ค์ •์ด๋‹ค.

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š”, ๊ณต์šฉ ์ค‘ ๊ต๋Ÿ‰์—์„œ ๋™์ผ ๊ธฐ๊ฐ„์— ๊ณ„์ธกํ•œ ๋ณ€ํ˜•๋ฅ ๊ณ„ ๋ฐ BWIM ๋ฐ์ดํ„ฐ์™€ ์ƒ์šฉ ๊ตฌ์กฐํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์„ ํ†ตํ•ด ๊ตฌ์ถ•๋œ ํ‰๊ฐ€ ๋Œ€์ƒ ๊ต๋Ÿ‰์˜ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ๊ณผ Shell-Solid ํ•ด์„๋ชจ๋ธ์„ ํ™œ์šฉํ•˜์—ฌ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ๋˜ํ•œ, BWIM ๊ณ„์ธก ๋ฐ์ดํ„ฐ๋ฅผ ์ฒ˜๋ฆฌํ•˜๋Š” ๋‘ ๊ฐ€์ง€ ๋ฐฉ๋ฒ•์„ ์„ ํ–‰์—ฐ๊ตฌ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ์ •์˜ํ•˜์˜€๋‹ค. ์ตœ์ข…์ ์œผ๋กœ, ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ๋“ค์„ ๋น„๊ตํ•˜์—ฌ, ๊ต๋Ÿ‰์˜ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ์‹œ ํ™œ์šฉ๋˜๋Š” ํ˜„์žฅ๊ณ„์ธก ๋ฐ์ดํ„ฐ์˜ ์ข…๋ฅ˜, ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ, BWIM ๊ณ„์ธก ๋ฐ์ดํ„ฐ ์ฒ˜๋ฆฌ ๋ฐฉ๋ฒ•์— ๋”ฐ๋ฅธ ํ‰๊ฐ€๊ฒฐ๊ณผ์˜ ์ฐจ์ด์— ๋Œ€ํ•ด ์ •๋Ÿ‰์ ์œผ๋กœ ๊ฒ€ํ† ํ•˜๊ณ , ์ผ๊ด€๋œ ์ˆ˜์ค€์˜ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€๋ฅผ ์œ„ํ•œ ํ‰๊ฐ€ ๋ฐฉ๋ฒ•์„ ์ œ์‹œํ•˜์˜€๋‹ค.

2. ๋Œ€์ƒ ๊ต๋Ÿ‰ ๋ฐ ๊ณ„์ธก ์ •๋ณด

ํšจ์œจ์ ์ธ ๊ณ„์ธก ์ˆ˜ํ–‰์„ ์œ„ํ•ด ํ™”๋ฌผ์ฐจ๋Ÿ‰ ๊ตํ†ต๋Ÿ‰์ด ๋งŽ์€ ๊ตฌ๊ฐ„์„ ์„ ์ •ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ KOSIS ๊ตญ๊ฐ€ํ†ต๊ณ„ ํฌํ„ธ(Korea Expressway Corporation, 2019) ์ž๋ฃŒ๋ฅผ ํ™œ์šฉํ•˜์—ฌ ์ผ๋ฐ˜๊ตญ๋„, ๊ตญ์ง€๋„, ์ง€๋ฐฉ๋„ ๋ณ„๋กœ ํ™”๋ฌผ์ฐจ๋Ÿ‰ ํ†ตํ–‰๋Ÿ‰ ์ƒ์œ„ ๊ตฌ๊ฐ„์„ ์กฐ์‚ฌํ•˜์˜€๋‹ค. ์ „์ˆ˜ ์กฐ์‚ฌ๋ฅผ ํ†ตํ•ด ์„ ์ •ํ•œ ๊ตฌ๊ฐ„ ์ค‘ BWIM ์‹œ์Šคํ…œ ์„ค์น˜๊ฐ€ ์šฉ์ดํ•˜๋ฉฐ, ๋ณ€ํ˜•๋ฅ ๊ณ„ ๋ถ€์ฐฉ์ด ๊ฐ€๋Šฅํ•œ ๊ฐ•๊ต๋Ÿ‰์„ ์„ ์ •ํ•˜์˜€๋‹ค. ์กฐ๊ฑด์— ๋ถ€ํ•ฉํ•˜๋Š” ๊ต๋Ÿ‰์œผ๋กœ ์ถฉ์ฒญ๋‚จ๋„ ์•„์‚ฐ์‹œ์— ์œ„์น˜ํ•œ ํญ 24.9 m, ๊ธธ์ด 89.9 m์˜ 2๊ฒฝ๊ฐ„ ๊ฐ•ํ•ฉ์„ฑ ๊ต๋Ÿ‰์ธ โ€˜์šฉ๋‘1๊ตโ€™๊ฐ€ ์ตœ์ข… ์„ ์ •๋˜์—ˆ๋‹ค.

๋ฐฑ์•”๋ฆฌ ๋ฐฉ๋ฉด ํŽธ๋„ 2์ฐจ์„  ๊ตฌ๊ฐ„์— ๋Œ€ํ•ด BWIM ์‹œ์Šคํ…œ์„ ์„ค์น˜ํ•˜์˜€๊ณ , ์ฐจ๋Ÿ‰ ํ†ตํ–‰์— ๋”ฐ๋ฅธ ์‘๋ ฅ๋ณ€ํ™”๋ฅผ ๊ณ„์ธกํ•˜๊ธฐ ์œ„ํ•ด ๊ฐ ๊ฒฝ๊ฐ„ ๊ธธ์ด์˜ 1/4 ๊ฐ„๊ฒฉ ๊ทธ๋ฆฌ๊ณ  ์–‘์ชฝ ์ง€์ ๋ถ€๋กœ๋ถ€ํ„ฐ ๊ฒฝ๊ฐ„ ๊ธธ์ด์˜ 40 %์ธ ์œ„์น˜์— ๋ณ€ํ˜•๋ฅ ๊ณ„๋ฅผ ์„ค์น˜ํ•˜์—ฌ 2019๋…„ 10์›” 12์ผ๋ถ€ํ„ฐ 10์›” 18์ผ๊นŒ์ง€ 1์ฃผ์ผ๊ฐ„ ๊ณ„์ธก์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ํ‰๊ฐ€ ๋Œ€์ƒ ํ”ผ๋กœ ์ƒ์„ธ๋Š” AASHTO LRFD (AASHTO, 2020) ๋ฐ ๋„๋กœ๊ต์„ค๊ณ„๊ธฐ์ค€(MOLIT, 2016)์— ๊ทผ๊ฑฐํ•˜์—ฌ ๋Œ€์ƒ ๊ต๋Ÿ‰์˜ ํ”ผ๋กœ ์ทจ์•ฝ ์ƒ์„ธ ์ค‘ 1๋ฒˆ ๋ฐ•์Šค์˜ ์ตœ๋Œ€ ์ •๋ชจ๋ฉ˜ํŠธ๋ถ€์— ์œ„์น˜ํ•œ ๊ต์ถ• ๋ฐฉํ–ฅ ์‘๋ ฅ์ด ์ž‘์šฉํ•˜๋Š” ํ•˜๋ถ€ ํ”Œ๋žœ์ง€์™€ ๋‹ค์ด์•„ํ”„๋žจ์˜ ์šฉ์ ‘๋ถ€๋ฅผ ์„ ์ •ํ•˜์˜€๋‹ค. ๋‹ค์ด์•„ํ”„๋žจ๊ณผ ํ•˜๋ถ€ํ”Œ๋žœ์ง€์˜ ํ•„๋ ›์šฉ์ ‘ ์ง€๋‹จ๋ถ€์˜ ๋ชจ์žฌ๋ถ€์—์„œ ํ”ผ๋กœ๊ท ์—ด์ด ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ์œผ๋ฉฐ, ์ด ์ƒ์„ธ์˜ ํ”ผ๋กœ ๋ฒ”์ฃผ๋Š” C'์ด๋‹ค. Fig. 1์€ ๋ณ€ํ˜•๋ฅ ๊ณ„์˜ ์„ค์น˜ ์œ„์น˜๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.

Fig. 1. Locations of the Strain Gauges and Fatigue-prone Detail
../../Resources/KSCE/Ksce.2022.42.5.0599/fig1.png

3. ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ ๊ตฌ์ถ•

๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ์ด ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•ด ๋‹จ์ˆœํ•ด์„๋ชจ๋ธ๊ณผ ์ •๋ฐ€ํ•ด์„๋ชจ๋ธ๋กœ ๊ตฌ๋ถ„ํ•˜์—ฌ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์„ ๊ตฌ์ถ•ํ•˜์˜€๋‹ค.

๋‹จ์ˆœํ•ด์„ ๋ชจ๋ธ์€ Fig. 2์™€ ๊ฐ™์ด ์ƒ์šฉ๊ตฌ์กฐํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์ธ Midas Civil์„ ์ด์šฉํ•ด ํ™˜์‚ฐ๋œ ํ•ฉ์„ฑ ๋‹จ๋ฉด์„ ๊ฐ–๋Š” 3์ฐจ์› ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ์„ ์ƒ์„ฑํ•˜์˜€๋‹ค(Midas IT, 2021). ํ”„๋กœ๊ทธ๋žจ ๋‚ด ์ฐจ๋Ÿ‰ํ•˜์ค‘ ์žฌํ•˜ ๊ธฐ๋Šฅ์„ ํ™œ์šฉํ•˜์—ฌ ์ฐจ๋Ÿ‰์˜ ์ถ• ํ•˜์ค‘ ๋ฐ ์ถ•๊ฐ„๊ฑฐ๋ฆฌ๋ฅผ ์ •์˜ํ•˜๊ณ , ํŽธ์‹ฌ ์žฌํ•˜ ๊ธฐ๋Šฅ์„ ํ™œ์šฉํ•˜์—ฌ ์ฐจ๋Ÿ‰์ด ํ†ต๊ณผํ•˜๋Š” ๊ต์ถ• ์ง๊ฐ๋ฐฉํ–ฅ ์œ„์น˜๋ฅผ ์ง€์ •ํ•˜์—ฌ ํ‰๊ฐ€ ๋Œ€์ƒ ํ”ผ๋กœ ์ƒ์„ธ์— ๋ฐœ์ƒํ•˜๋Š” ๊ณต์นญ์‘๋ ฅ์— ๋Œ€ํ•œ ์˜ํ–ฅ์„  ํ•ด์„์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค.

์ •๋ฐ€๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์€ Fig. 3(a)์™€ ๊ฐ™์ด ์ƒ์šฉ ์œ ํ•œ์š”์†Œํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์ธ ABAQUS 2021์„ ์ด์šฉํ•ด 3์ฐจ์› Shell-Solid ํ•ด์„๋ชจ๋ธ์„ ์ƒ์„ฑํ•˜์˜€๋‹ค. ๊ต๋Ÿ‰์˜ ๋ฐ”๋‹ฅํŒ์€ solid ์š”์†Œ๋ฅผ ๊ทธ๋ฆฌ๊ณ  ๊ฐ•๋ฐ•์Šค์™€ ํฌ๋กœ์Šคํ”„๋ ˆ์ž„์€ shell ์š”์†Œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค(Dassault Systemes, 2021). ์ฐจ๋Ÿ‰ ํ•˜์ค‘์€ ๋„๋กœ๊ต์„ค๊ณ„๊ธฐ์ค€(MOLIT, 2016)์— ๊ทผ๊ฑฐํ•˜์—ฌ ๊ณ„์‚ฐ๋œ ์ง์‚ฌ๊ฐํ˜•์˜ ๋ฐ”ํ€ด ์ ‘์ง€ ๋ฉด์ ์ธ 200 mm ร— 600 mm์— ์••๋ ฅ์œผ๋กœ ์ ์šฉํ•˜์˜€์œผ๋ฉฐ, ํ”ผ๋กœ ์ƒ์„ธ์— ์ตœ๋Œ€ ์‘๋ ฅ์„ ๋ฐœ์ƒ์‹œํ‚ค๋Š” ์ฐจ๋Ÿ‰์˜ ์œ„์น˜๋ฅผ ์ฐพ๊ธฐ ์œ„ํ•ด User-defined subroutine์„ ์ด์šฉํ•˜์—ฌ ํ•˜์ค‘์˜ ์œ„์น˜๋ฅผ ๋ณ€ํ™”์‹œํ‚ค๋ฉฐ ๋ฐ˜๋ณตํ•ด์„์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. Shell-Solid ํ•ด์„๋ชจ๋ธ์˜ ๊ณต์นญ์‘๋ ฅ์„ ๊ณ„์‚ฐํ•˜๊ธฐ ์œ„ํ•ด์„œ ๊ตญ๋ถ€์ ์ธ ์‘๋ ฅ์ง‘์ค‘ ํšจ๊ณผ๋ฅผ ๋ฐฐ์ œํ•ด์•ผ ํ•œ๋‹ค๋Š” ์„ ํ–‰์—ฐ๊ตฌ(Hobbacher, 2009)์— ๋”ฐ๋ผ, Fig. 3(b)์™€ ๊ฐ™์ด ํ”ผ๋กœ ์ƒ์„ธ๋กœ๋ถ€ํ„ฐ ์‘๋ ฅ ๋ฐฉํ–ฅ์œผ๋กœ ๊ฐ๊ฐ 200 mm, 400 mm, 600 mm์— ํ•ด๋‹นํ•˜๋Š” ์œ„์น˜๋ฅผ ๊ธฐ์ค€์ ์œผ๋กœ ํ•˜์—ฌ Quadratic extrapolation์„ ํ†ตํ•ด ํ”ผ๋กœ ์ƒ์„ธ์— ์ž‘์šฉํ•˜๋Š” ๊ณต์นญ์‘๋ ฅ์„ ์ถ”์ •ํ•˜์˜€๋‹ค.

๊ตฌ์ถ•๋œ ๋‘ ์ข…๋ฅ˜์˜ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ๊ฒ€์ฆ์„ ์œ„ํ•ด BWIM ๊ณ„์ธก ๊ธฐ๋ก์œผ๋กœ๋ถ€ํ„ฐ ๊ต๋Ÿ‰ ์œ„๋ฅผ ์ฐจ๋Ÿ‰์ด ๋‹จ๋…์ฃผํ–‰ํ•˜๋Š” ๊ฒฝ์šฐ๋ฅผ ์กฐ์‚ฌํ•˜์˜€๋‹ค. ๋™์ผํ•œ ์ฐจ๋Ÿ‰ ํ•˜์ค‘ ์กฐ๊ฑด์œผ๋กœ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์— ์žฌํ•˜ํ•˜์—ฌ ํ”ผ๋กœ ์ƒ์„ธ์— ๋ฐœ์ƒํ•œ ์‘๋ ฅ๋ฒ”์œ„๋ฅผ ํ•ด๋‹น ์‹œ๊ฐ„์— ๋ณ€ํ˜•๋ฅ ๊ณ„์— ๊ณ„์ธก๋œ ์‘๋ ฅ๊ณผ ๋น„๊ตํ•˜์˜€๋‹ค. ๊ณ„์ธก ๊ธฐ๊ฐ„ ๋‚ด์— ์ด 1,561ํšŒ์˜ ์ฐจ๋Ÿ‰ ๋‹จ๋…์ฃผํ–‰์ด ์‹๋ณ„๋˜์—ˆ์œผ๋ฉฐ ์‘๋ ฅ๋ฒ”์œ„๋Š” ํ‰๊ท ์ ์œผ๋กœ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ์—์„œ 12 %, Shell-Solid ํ•ด์„๋ชจ๋ธ์—์„œ 4 % ๋” ํฌ๊ฒŒ ํ‰๊ฐ€๋จ์„ ํ™•์ธํ•˜์˜€๋‹ค.

Fig. 2. Frame Model
../../Resources/KSCE/Ksce.2022.42.5.0599/fig2.png
Fig. 3. Shell-Solid Model
../../Resources/KSCE/Ksce.2022.42.5.0599/fig3.png

4. ํ”ผ๋กœ ์‹ ๋ขฐ๋„ ํ‰๊ฐ€

4.1 ํ”ผ๋กœ ํ•œ๊ณ„์ƒํƒœ

์ฐจ๋Ÿ‰ ํ†ตํ–‰ ์‹œ ํ”ผ๋กœ ์ƒ์„ธ์— ๋ฐœ์ƒํ•˜๋Š” ์‘๋ ฅ์— ์˜ํ•œ ํ”ผ๋กœ ์†์ƒ ๋ˆ„์  ํ•œ๊ณ„์ƒํƒœํ•จ์ˆ˜๋Š” Eq. (1)๊ณผ ๊ฐ™์ด ์ •์˜ํ•  ์ˆ˜ ์žˆ๋‹ค(Kwon and Frangopol, 2010). ๋ถ€์žฌ์˜ ํ”ผ๋กœ ๋“ฑ๊ธ‰์— ๋”ฐ๋ฅธ ํ•œ๊ณ„ ๋ฐ˜๋ณต์‘๋ ฅ ํšŸ์ˆ˜ ๋Œ€๋น„ ๋ชฉํ‘œ ์ˆ˜๋ช… ๋™์•ˆ ๋ฐœ์ƒํ•˜๋Š” ๋ฐ˜๋ณต์‘๋ ฅ ํšŸ์ˆ˜๋ฅผ ํ†ตํ•ด ํ”ผ๋กœ ์†์ƒ ๋ˆ„์ ์„ ํ‰๊ฐ€ํ•œ๋‹ค. ํ‰๊ฐ€๋ฅผ ์œ„ํ•œ ์ผํ‰๊ท ๋ฐ˜๋ณต์‘๋ ฅํšŸ์ˆ˜(Average Daily Stress Cycles, ADSC)์™€ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„(S$_{eff}$)๋Š” ํ˜„์žฅ๊ณ„์ธก ๋ฐ์ดํ„ฐ๋กœ๋ถ€ํ„ฐ ์ถ”์ •ํ•œ๋‹ค.

(1)
$ g(X)=\Delta -e\bullet D{mrm}{for}\\ \\ {D}=\sum_{{i}}\dfrac{{n}_{{i}}}{{N}_{{i}}}=365\bullet{ADSC}\bullet\dfrac{(1+\alpha)^{{y}}-1}{\ln(1+\alpha)}\bullet\dfrac{\left({S}_{{eff}}\right)^{{m}}}{{A}} $

์—ฌ๊ธฐ์„œ, $\Delta$๋Š” ํ•œ๊ณ„ ์†์ƒ ๋ˆ„์  ์ง€์ˆ˜, $e$๋Š” ๊ณ„์ธก ์˜ค์ฐจ, $\alpha$๋Š” ์—ฐ๊ฐ„ ๊ตํ†ต๋Ÿ‰ ์ฆ๊ฐ€์œจ, $y$๋Š” ๊ณต์šฉ์—ฐ์ˆ˜, $m$์€ ๊ฐ•์žฌ์˜ ์žฌ๋ฃŒ ์ƒ์ˆ˜, $A$๋Š” ํ”ผ๋กœ ์ƒ์„ธ ๊ณ„์ˆ˜๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ํ•œ๊ณ„์ƒํƒœ์‹์„ ๊ตฌ์„ฑํ•˜๋Š” ํŒŒ๋ผ๋ฏธํ„ฐ๋“ค์— ๋Œ€ํ•œ ํ™•๋ฅ ๋ณ€์ˆ˜์˜ ๋ถ„ํฌ๋Š” Table 1์—์„œ ๊ธฐ์ˆ ํ•˜์˜€๋‹ค. ํ•œ๊ณ„์ƒํƒœํ•จ์ˆ˜๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ, ๊ณต์šฉ์—ฐ์ˆ˜์— ๋”ฐ๋ฅธ ํ”ผ๋กœ ์‹ ๋ขฐ๋„์ง€์ˆ˜ $\beta$๋ฅผ First-Order-Reliability- Method (FORM)์„ ํ†ตํ•˜์—ฌ ์ถ”์ •ํ•˜์˜€๋‹ค.

Table 1. Parameters for the Fatigue Reliability Evaluation

Parameter

Distribution

Source

Type

Value

Fatigue detail coefficient (MPa3), $A$

Lognormal

$\lambda_{A}=23.113,\: \zeta_{A}=0.145$

Chung(2004), Keating and Fisher(1986)

Miner's critical damage accumulation index, $\Delta$

Lognormal

$\lambda_{\Delta}=1,\: \zeta_{\Delta}=0.3$

Wirsching(1984)

Measurement error, $e$

Lognormal

$\lambda_{e}=1,\: \zeta_{e}=0.03$

Frangopol et al.(2008)

Traffic increase rate (per year), $\alpha$

Deterministic

0.0104

Shin et al.(2007)

Material constant, $m$

Deterministic

3

AASHTO(2020)

Time (year), $y$

variable

increment = 0.1

4.2 ๋ณ€ํ˜•๋ฅ  ์ธก์ •๊ฐ’์„ ํ™œ์šฉํ•œ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„(S$_{eff}$) ๋ฐ ์ผํ‰๊ท ๋ฐ˜๋ณต์‘๋ ฅํšŸ์ˆ˜(ADSC) ์ถ”์ •

1์ฃผ์ผ์˜ ๊ณ„์ธก ๋ฐ์ดํ„ฐ ์ค‘ 0์‹œ๋ถ€ํ„ฐ 24์‹œ๊นŒ์ง€ 24์‹œ๊ฐ„ ๋™์•ˆ ๊ณ„์ธก์†์‹ค์ด๋‚˜ ์˜ค๋ฅ˜๊ฐ€ ์—†์ด ์˜จ์ „ํžˆ ์ˆ˜ํ–‰๋œ 5์ผ๊ฐ„์˜ ๋ฐ์ดํ„ฐ๋งŒ์„ ํ”ผ๋กœ ํ‰๊ฐ€์— ํ™œ์šฉํ•˜์˜€๋‹ค. ๋ณ€ํ˜•๋ฅ ์„ ํ†ตํ•œ ์‘๋ ฅ์ด๋ ฅ ๋ฐ์ดํ„ฐ๋กœ๋ถ€ํ„ฐ Rainflow counting method (Downing and Socie, 1982)๋ฅผ ํ†ตํ•ด ์‘๋ ฅ๋ฒ”์œ„ ํžˆ์Šคํ† ๊ทธ๋žจ์„ ์ถ”์ถœํ•˜์˜€๋‹ค. ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„(S$_{eff}$)์„ ๊ณผ์†Œํ‰๊ฐ€ํ•˜๋Š” ๊ฒƒ์„ ๋ฐฉ์ง€ํ•˜๊ธฐ ์œ„ํ•ด 7 MPa ์ดํ•˜์˜ ์‘๋ ฅ๋ฒ”์œ„์— Cut-off๋ฅผ ์ ์šฉํ•˜์˜€๋‹ค(Connor et al., 2004; Hodgson et al., 2006; Kwon and Frangopol, 2010). ์‘๋ ฅ๋ฒ”์œ„ ํžˆ์Šคํ† ๊ทธ๋žจ์œผ๋กœ๋ถ€ํ„ฐ ์ผํ‰๊ท ๋ฐ˜๋ณต์‘๋ ฅํšŸ์ˆ˜(ADSC)๋ฅผ ์‚ฐ์ •ํ•˜๊ณ , Minerโ€™s rule (Miner, 1945)์— ๋”ฐ๋ผ Eq. (2)์™€ ๊ฐ™์ด ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„(S$_{eff}$)์„ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค. Fig. 4๋Š” ๊ฒ€ํ†  ๋Œ€์ƒ ํ”ผ๋กœ ์ƒ์„ธ์—์„œ ๊ณ„์ธก๋œ ์‘๋ ฅ๋ฒ”์œ„ ํžˆ์Šคํ† ๊ทธ๋žจ๊ณผ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.

(2)
$S_{eff}=\left[\sum_{i}\gamma_{i}\left(\triangle S_{i}\right)^{3}\right]^{\dfrac{1}{3}}$

์—ฌ๊ธฐ์„œ, $\triangle S_{i}$๋Š” ์‘๋ ฅ๋ฒ”์œ„ ํžˆ์Šคํ† ๊ทธ๋žจ์ธ Fig. 4์—์„œ I๋ฒˆ์งธ ์‘๋ ฅ๋ฒ”์œ„, $\gamma_{i}$์€ i๋ฒˆ์งธ ์‘๋ ฅ๋ฒ”์œ„ $\triangle S_{i}$์˜ ๋น„์œจ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

Fig. 4. Measured Stress Range Histogram
../../Resources/KSCE/Ksce.2022.42.5.0599/fig4.png

4.3 BWIM ์ธก์ •๊ฐ’์„ ํ™œ์šฉํ•œ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„(S$_{eff}$) ๋ฐ ์ผํ‰๊ท ๋ฐ˜๋ณต์‘๋ ฅํšŸ์ˆ˜(ADSC) ์ถ”์ •

๋ณ€ํ˜•๋ฅ  ์ธก์ •๊ฐ’๊ณผ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ, 1์ฃผ์ผ ๋™์•ˆ์˜ ๊ณ„์ธก ๋ฐ์ดํ„ฐ ์ค‘ ๊ณ„์ธก์ด ์˜จ์ „ํžˆ ์ˆ˜ํ–‰๋œ 5์ผ์˜ ๋ฐ์ดํ„ฐ๋งŒ์„ ํ”ผ๋กœ ํ‰๊ฐ€์— ํ™œ์šฉํ•˜์˜€๋‹ค. ๋ณธ๊ฒฉ์ ์ธ S$_{eff}$ ๋ฐ ADSC ์ถ”์ •์— ์•ž์„œ ์„ ํ–‰์—ฐ๊ตฌ(Kim and Song, 2019; Sivakumar et al., 2011)์— ๊ธฐ๋ฐ˜ํ•˜์—ฌ ์•„๋ž˜ ์ ˆ์ฐจ์— ๋”ฐ๋ผ BWIM ๋ฐ์ดํ„ฐ ์ค‘ ์ผ๋ถ€ ๋ถ€์ •ํ™•ํ•œ ๊ณ„์ธก ๊ธฐ๋ก๋“ค์„ ๋ฐฐ์ œํ•˜์˜€๋‹ค.

1. ๊ณ„์ธก๋œ ์ฐจ๋Ÿ‰ ์ด ์ค‘๋Ÿ‰(Gross Vehicle Weight, GVW)๊ณผ ์ถ• ํ•˜์ค‘๋“ค์˜ ์ดํ•ฉ์˜ ์ฐจ๊ฐ€ 10 % ์ด๋‚ด์—ฌ์•ผ ํ•œ๋‹ค.

2. ์ฐจ๋Ÿ‰์˜ GVW๋Š” 0.8 ton ์ด์ƒ, 100 ton ์ดํ•˜์—ฌ์•ผ ํ•œ๋‹ค.

3. ์ฐจ๋Ÿ‰์˜ ๊ธธ์ด๋Š” 2 m ์ด์ƒ, 36 m ์ดํ•˜์—ฌ์•ผ ํ•œ๋‹ค.

4. ์ฐจ๋Ÿ‰์˜ ๊ฐ€์žฅ ๋‚ฎ์€ ์ถ• ํ•˜์ค‘์ด GVW์˜ 5 %๋ฅผ ์ดˆ๊ณผํ•ด์•ผ ํ•œ๋‹ค.

5. ์ฐจ๋Ÿ‰ ๊ฐ„ ์—ฐํ–‰์€ ์ตœ์†Œ 0.3์ดˆ ์ด์ƒ์ด์—ฌ์•ผ ํ•œ๋‹ค.

BWIM ๋ฐ์ดํ„ฐ๋ฅผ ํ™œ์šฉํ•œ ํ”ผ๋กœ ํ‰๊ฐ€ ์‹œ, ๋‘ ๊ฐ€์ง€ ๋ฐ์ดํ„ฐ ์ฒ˜๋ฆฌ ๋ฐฉ๋ฒ•์— ์˜ํ•ด S$_{eff}$ ๋ฐ ADSC๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ฒซ ๋ฒˆ์งธ๋Š”, ์ฐจ๋Ÿ‰์ด์ค‘๋Ÿ‰(Gross vehicle weight, GVW) ํžˆ์Šคํ† ๊ทธ๋žจ์„ ๋ฐ”ํƒ•์œผ๋กœ ์œ ํšจํŠธ๋Ÿญํ•˜์ค‘๊ณผ ์ผํ‰๊ท ํŠธ๋Ÿญํ†ตํ–‰๋Ÿ‰(Average Daily Truck Traffic, ADTT)๋ฅผ ์ถ”์ •ํ•˜๋Š” ๋ฐฉ๋ฒ•์œผ๋กœ, ์œ ํšจํŠธ๋Ÿญํ•˜์ค‘์€ GVW ํžˆ์Šคํ† ๊ทธ๋žจ์œผ๋กœ๋ถ€ํ„ฐ Eq. (3)๊ณผ ๊ฐ™์ด Root-Mean-Cube method์— ์˜ํ•ด ์‚ฐ์ •๋œ๋‹ค(Moses et al., 1987). Fig. 5๋Š” GVW ํžˆ์Šคํ† ๊ทธ๋žจ๊ณผ ์œ ํšจํŠธ๋Ÿญํ•˜์ค‘์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ณ„์ธก๋œ ์ฐจ๋Ÿ‰ ๋ฐ์ดํ„ฐ ์ค‘ ํ”ผ๋กœ ์†์ƒ์— ๊ฑฐ์˜ ๊ธฐ์—ฌํ•˜์ง€ ์•Š๋Š” GVW 100 kN ๋ฏธ๋งŒ์˜ ์ฐจ๋Ÿ‰์„ ์ œ์™ธํ•œ ํŠธ๋Ÿญ์— ๋Œ€ํ•˜์—ฌ ์œ ํšจํŠธ๋Ÿญํ•˜์ค‘์„ ์‚ฐ์ •ํ•˜์˜€๋‹ค(Iatsko et al., 2020).

(3)
$W_{eff}=\left[\sum_{i}f_{i}W_{i}^{3}\right]^{\dfrac{1}{3}}$

์—ฌ๊ธฐ์„œ, $W_{i}$๋Š” Fig. 5์— ๋‚˜ํƒ€๋‚ธ GVW ํžˆ์Šคํ† ๊ทธ๋žจ์˜ i๋ฒˆ์งธ GVW ์ด๋ฉฐ, $f_{i}$์€ i๋ฒˆ์งธ GVW ($W_{i}$)์˜ ๋น„์œจ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

์ถ”์ •๋œ ์œ ํšจํŠธ๋Ÿญํ•˜์ค‘์„ ๊ต๋Ÿ‰์˜ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์— ์ ์šฉํ•˜์—ฌ ๊ณ„์‚ฐํ•œ ์ตœ๋Œ€ ๋ฐ ์ตœ์†Œ ๊ณต์นญ์‘๋ ฅ์˜ ์ฐจ์ด๋กœ๋ถ€ํ„ฐ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด๋•Œ, ์œ ํšจํŠธ๋Ÿญํ•˜์ค‘์€ ์ฐจ์„ ๊ณผ๋Š” ๊ด€๊ณ„์—†์ด ๊ฒ€ํ†  ๋Œ€์ƒ ํ”ผ๋กœ ์ƒ์„ธ์— ๊ฐ€์žฅ ๋ถˆ๋ฆฌํ•œ ํ•˜์ค‘ํšจ๊ณผ๋ฅผ ์œ ๋ฐœํ•˜๋Š” ์œ„์น˜์— ์ ์šฉํ•œ๋‹ค. Fig. 6(a)๋Š” ์˜ํ–ฅ์„  ํ•ด์„๊ฒฐ๊ณผ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ๊ณ„์‚ฐ๋œ ์˜ํ–ฅ๋ฉด์œผ๋กœ๋ถ€ํ„ฐ ํ”ผ๋กœ ์ƒ์„ธ์— ๊ฐ€์žฅ ๋ถˆ๋ฆฌํ•œ ํ•˜์ค‘ํšจ๊ณผ๋ฅผ ์œ ๋ฐœํ•˜๋Š” ์ฐจ๋Ÿ‰์˜ ์œ„์น˜๋ฅผ ์ถ”์ •ํ•œ ๊ฒƒ์ด๋‹ค. Fig. 6(b)๋Š” ๊ต์ถ•๋ฐฉํ–ฅ์„ ๋”ฐ๋ผ ํ”ผ๋กœ ์ƒ์„ธ์— ๊ฐ€์žฅ ๋ถˆ๋ฆฌํ•˜๊ฒŒ ์ž‘์šฉํ•˜๋Š” ๊ฒฝ์šฐ์˜ ๋‹จ์œ„ ํ•˜์ค‘ 1 N์— ๋Œ€ํ•œ ๊ณต์นญ์‘๋ ฅ์˜ ์˜ํ–ฅ์„ ์„ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค.

๋‘ ๋ฒˆ์งธ๋Š”, BWIM ๋ฐ์ดํ„ฐ๋กœ๋ถ€ํ„ฐ ์–ป์–ด์ง€๋Š” ์ฐจ๋Ÿ‰์˜ ๊ต๋Ÿ‰ ์ง„์ž… ์‹œ๊ฐ„, ์ฃผํ–‰ ์ฐจ์„ , ์ฃผํ–‰ ์†๋„, ์ถ• ํ•˜์ค‘ ๋ฐ ์ถ•๊ฐ„๊ฑฐ๋ฆฌ์™€ ๊ฐ™์€ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์„ ๋ฐ”ํƒ•์œผ๋กœ ์˜ํ–ฅ์„  ์ค‘์ฒฉ์„ ํ†ตํ•ด ์‹œ๊ณ„์—ด ์‘๋ ฅ์ด๋ ฅ์„ ์ถ”์ถœํ•˜๊ณ , ์ด๋ฅผ ํ†ตํ•ด S$_{eff}$ ๋ฐ ADSC๋ฅผ ์ถ”์ •ํ•˜๋Š” ๋ฐฉ๋ฒ•์ด๋‹ค. ์‹œ๊ณ„์—ด ์‘๋ ฅ์ด๋ ฅ์„ ํ†ตํ•œ S$_{eff}$ ๋ฐ ADSC๋ฅผ ์ถ”์ • ์‹œ 4.2์ ˆ์˜ ๋ณ€ํ˜•๋ฅ  ์ธก์ •๊ฒฐ๊ณผ์™€ ๋™์ผํ•˜๊ฒŒ 7 MPa ์ดํ•˜์˜ ์‘๋ ฅ๋ฒ”์œ„๋Š” ๊ณ„์‚ฐ์—์„œ ์ œ์™ธํ•˜์˜€๋‹ค. Fig. 7(a)๋Š” ์ฐจ์„ ์— ๋”ฐ๋ฅธ ์ฐจ๋Ÿ‰์˜ ์œ„์น˜, Fig. 7(b)๋Š” ์ฐจ์„ ์— ๋”ฐ๋ฅธ ๋‹จ์œ„ ํ•˜์ค‘ 1 N์— ๋Œ€ํ•œ ์˜ํ–ฅ์„ ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋˜ํ•œ, Fig. 8์€ ์ฐจ๋Ÿ‰ ์ถ• ํ•˜์ค‘๋“ค์˜ ์œ„์น˜๋ฅผ ๋‚˜ํƒ€๋‚ธ ์˜ˆ์‹œ์ด๋ฉฐ ๋™์ผํ•œ ์ƒ‰์ƒ์€ ํ•˜๋‚˜์˜ ์ฐจ๋Ÿ‰์„ ์˜๋ฏธํ•œ๋‹ค. Fig. 9๋Š” BWIM ๋ฐ์ดํ„ฐ๋กœ๋ถ€ํ„ฐ ์ถ”์ถœ๋œ ์‹œ๊ณ„์—ด ์‘๋ ฅ์ด๋ ฅ์˜ ์‘๋ ฅ๋ฒ”์œ„ ํžˆ์Šคํ† ๊ทธ๋žจ ๋ฐ ์œ ํšจ์‘๋ ฅ๋ฒ”์œ„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.

Fig. 5. Measured GVW Histogram
../../Resources/KSCE/Ksce.2022.42.5.0599/fig5.png
Fig. 6. Vehicle Location Causes the Worst Load Effect on the Fatigue-prone Detail
../../Resources/KSCE/Ksce.2022.42.5.0599/fig6.png
Fig. 7. Location of the Vehicle Along the Traffic Lane
../../Resources/KSCE/Ksce.2022.42.5.0599/fig7.png
Fig. 8. Locations of Vehicle Axles in Two Lanes - 2019.10.22 17:58:45
../../Resources/KSCE/Ksce.2022.42.5.0599/fig8.png
Fig. 9. Stress Range Histogram Obtained from the BWIM Time-series Stress History
../../Resources/KSCE/Ksce.2022.42.5.0599/fig9.png

4.4 ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ ๋น„๊ต ๋ฐ ๋ถ„์„

ํ”ผ๋กœ ํ•œ๊ณ„์ƒํƒœํ•จ์ˆ˜, ๋ณ€ํ˜•๋ฅ  ๋ฐ BWIM ๊ณ„์ธก ๋ฐ์ดํ„ฐ๋กœ๋ถ€ํ„ฐ ์ถ”์ •๋œ S$_{eff}$ ๋ฐ ADSC๋ฅผ ํ™œ์šฉํ•˜์—ฌ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. Fig. 10์€ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€์— ํ™œ์šฉ๋œ ๊ฐ ๋ฐฉ๋ฒ•์— ๋”ฐ๋ฅธ ํ‰๊ฐ€์ ˆ์ฐจ๋ฅผ ๋„์‹ํ™”ํ•œ ๊ฒƒ์ด๋‹ค. Fig. 11๋Š” ํ˜„์žฅ๊ณ„์ธก ๋ฐ์ดํ„ฐ ์ข…๋ฅ˜ ๋ฐ ๊ตฌ์กฐํ•ด์„ ๋ชจ๋ธ์— ๋”ฐ๋ฅธ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ๋“ค์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

ํ”ผ๋กœ์ˆ˜๋ช…์€ ํ”ผ๋กœ ์ƒ์„ธ์— ๋ฐœ์ƒํ•˜๋Š” ์‘๋ ฅ์— ์ง์ ‘์ ์ธ ์˜ํ–ฅ์„ ๋ฐ›๊ธฐ ๋•Œ๋ฌธ์—, ๋ณ€ํ˜•๋ฅ  ์ธก์ •๊ฒฐ๊ณผ๋กœ๋ถ€ํ„ฐ ์ถ”์ •ํ•œ ํ”ผ๋กœ ์‹ ๋ขฐ๋„๊ฐ€ ๊ฐ€์žฅ ์‹ ๋ขฐ๋„๊ฐ€ ๋†’๋‹ค๊ณ  ๋ณผ ์ˆ˜ ์žˆ๋‹ค. ๋ณ€ํ˜•๋ฅ  ์ธก์ •๊ฐ’์œผ๋กœ๋ถ€ํ„ฐ ์ถ”์ •ํ•œ ๋ชฉํ‘œ ์„ค๊ณ„์ˆ˜๋ช… 100๋…„์— ๋Œ€ํ•œ ์‹ ๋ขฐ๋„์ง€์ˆ˜($\beta_{100yr}$)๋Š” 10.32์ด๋‹ค. ์ด๋ฅผ ๊ธฐ์ค€์œผ๋กœ ๊ฐ๊ฐ์˜ ํ‰๊ฐ€ ๋ฐฉ๋ฒ•์˜ ํ”ผ๋กœ ์‹ ๋ขฐ๋„์ง€์ˆ˜๊ฐ€ $\beta_{100yr}$๊ณผ ๊ฐ™์•„์ง€๋Š” ๊ณต์šฉ์—ฐ์ˆ˜๋ฅผ ์ •๋Ÿ‰์ ์œผ๋กœ ๋น„๊ตํ•˜์˜€๋‹ค. BWIM ๋ฐ์ดํ„ฐ์˜ GVW ํžˆ์Šคํ† ๊ทธ๋žจ์„ ํ†ตํ•œ ํ‰๊ฐ€๊ฒฐ๊ณผ์—์„œ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ์€ 40.3๋…„, Shell-Solid ํ•ด์„๋ชจ๋ธ์€ 33.3๋…„์œผ๋กœ ์‹ค์ œ๋ณด๋‹ค ์ตœ๋Œ€ 3๋ฐฐ๊ฐ€๋Ÿ‰ ํ”ผ๋กœ ์†์ƒ์— ๋Œ€ํ•ด ๋ณด์ˆ˜์ ์œผ๋กœ ํ‰๊ฐ€ํ•œ๋‹ค. BWIM ๋ฐ์ดํ„ฐ์—์„œ ์–ป์„ ์ˆ˜ ์žˆ๋Š” ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ๋“ค์„ ๋ชจ๋‘ ๋ฐ˜์˜ํ•˜์—ฌ ์‹œ๊ณ„์—ด ์‘๋ ฅ์ด๋ ฅ์„ ์ถ”์ถœํ•˜๊ณ , ์ด๋ฅผ ํ†ตํ•˜์—ฌ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€๋ฅผ ์ˆ˜ํ–‰ํ•  ๊ฒฝ์šฐ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ์€ 65.4๋…„, Shell- Solid ํ•ด์„๋ชจ๋ธ์€ 88.5๋…„์œผ๋กœ ๋ณด๋‹ค ์‹ค์ œ์™€ ์œ ์‚ฌํ•œ ์ˆ˜์ค€์œผ๋กœ ํ”ผ๋กœ์— ๋Œ€ํ•œ ์†์ƒ์„ ํ‰๊ฐ€ํ•  ์ˆ˜ ์žˆ์Œ์„ ํ™•์ธํ•˜์˜€๋‹ค.

๊ฐ ๋ฐฉ๋ฒ•์— ๋”ฐ๋ฅธ ํ‰๊ฐ€๊ฒฐ๊ณผ๋กœ๋ถ€ํ„ฐ ๊ต๋Ÿ‰์˜ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ์‹œ ํ™œ์šฉ๋˜๋Š” ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ๊ณผ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์— ์˜ํ•ด ํ‰๊ฐ€๊ฒฐ๊ณผ๊ฐ€ ๋‹ฌ๋ผ์ง€๋ฉฐ, ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ๋ณด๋‹ค๋Š” ๊ณ ๋ ค๋˜๋Š” ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์— ์˜ํ•œ ์˜ํ–ฅ์ด ๋” ์ง€๋ฐฐ์ ์ธ ์˜ํ–ฅ์„ ๋ฏธ์นจ์„ ํ™•์ธํ•˜์˜€๋‹ค. ๋˜ํ•œ, ์˜ํ–ฅ์„  ๋ฐ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ๋ฅผ ํ†ตํ•ด Shell-Solid ํ•ด์„๋ชจ๋ธ์ด ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ๋ณด๋‹ค ์ฐจ๋Ÿ‰์˜ ์œ„์น˜์™€ ๊ฐ™์€ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์— ๋” ๋ฏผ๊ฐํ•œ ์˜ํ–ฅ์„ ๋ฐ›๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค.

Fig. 10. Schematic Diagram of the Fatigue Reliability Evaluation Procedure
../../Resources/KSCE/Ksce.2022.42.5.0599/fig10.png
Fig. 11. Fatigue Reliability Evaluation Results
../../Resources/KSCE/Ksce.2022.42.5.0599/fig11.png

5. ๊ฒฐ ๋ก 

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ํ˜„์žฅ๊ณ„์ธก ๋ฐ์ดํ„ฐ์˜ ์ข…๋ฅ˜๊ฐ€ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ํ™•์ธํ•˜๊ธฐ ์œ„ํ•ด, ์‹ค์ œ ๊ณต์šฉ ์ค‘์ธ ๊ฐ•๊ต๋Ÿ‰์—์„œ ๋™์ผํ•œ ๊ธฐ๊ฐ„ ๋™์•ˆ ๋ณ€ํ˜•๋ฅ ๊ณ„ ๋ฐ BWIM ๊ณ„์ธก์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. BWIM ๋ฐ์ดํ„ฐ๋ฅผ ํ™œ์šฉํ•œ ํ”ผ๋กœ ํ‰๊ฐ€ ์‹œ ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ์ด ํ‰๊ฐ€๊ฒฐ๊ณผ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ํ™•์ธํ•˜๊ธฐ ์œ„ํ•ด ์ƒ์šฉ ๊ตฌ์กฐํ•ด์„ํ”„๋กœ๊ทธ๋žจ์„ ํ™œ์šฉํ•˜์—ฌ ๋Œ€์ƒ ๊ต๋Ÿ‰์˜ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ ๋ฐ Shell-Solid ํ•ด์„๋ชจ๋ธ์„ ๊ตฌ์ถ•ํ•˜์˜€๋‹ค. GVW ํžˆ์Šคํ† ๊ทธ๋žจ์„ ํ™œ์šฉํ•˜๋Š” ๋ฐฉ๋ฒ•๊ณผ ์ฐจ๋Ÿ‰์˜ ๊ต๋Ÿ‰ ์ง„์ž… ์‹œ๊ฐ„, ์ฃผํ–‰ ์ฐจ์„ , ์ฃผํ–‰ ์†๋„, ์ถ• ํ•˜์ค‘ ๋ฐ ์ถ•๊ฐ„๊ฑฐ๋ฆฌ ๋“ฑ์˜ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•˜๋Š” ๋‘ ๊ฐ€์ง€ ๋ฐฉ๋ฒ•์„ ํ†ตํ•ด S$_{eff}$ ๋ฐ ADSC๋ฅผ ์ถ”์ •ํ•˜์˜€์œผ๋ฉฐ, ์ด๋กœ๋ถ€ํ„ฐ BWIM ๋ฐ์ดํ„ฐ์˜ ์ฒ˜๋ฆฌ๋ฐฉ๋ฒ•์— ๋”ฐ๋ฅธ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ๊ฒฐ๊ณผ์˜ ์ฐจ์ด๋ฅผ ๋น„๊ตํ•˜์˜€๋‹ค.

๊ฐ ๋ฐฉ๋ฒ•๋“ค์— ๋”ฐ๋ผ ์ถ”์ •๋œ S$_{eff}$ ๋ฐ ADSC๋ฅผ ํ†ตํ•˜์—ฌ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ ํ•ด์„์„ ์ˆ˜ํ–‰ํ•˜์˜€๊ณ , ๊ฒฐ๊ณผ๋“ค์„ ์ •๋Ÿ‰์ ์œผ๋กœ ๋น„๊ตํ•˜์˜€๋‹ค. ๋ณ€ํ˜•๋ฅ  ์ธก์ •๊ฐ’์œผ๋กœ ํ‰๊ฐ€ํ•œ ํ”ผ๋กœ ์‹ ๋ขฐ๋„($\beta_{100yr}$)์ธ 10.32๋ฅผ ๊ธฐ์ค€์œผ๋กœ ๊ฐ๊ฐ์˜ ํ‰๊ฐ€ ๋ฐฉ๋ฒ•๋“ค์˜ ํ”ผ๋กœ ์‹ ๋ขฐ๋„๊ฐ€ $\beta_{100yr}$์™€ ๊ฐ™์•„์ง€๋Š” ๊ณต์šฉ์—ฐ์ˆ˜๋ฅผ ์ •๋Ÿ‰์ ์œผ๋กœ ๋น„๊ตํ•˜์˜€๋‹ค. BWIM GVW ํžˆ์Šคํ† ๊ทธ๋žจ์„ ํ†ตํ•œ ํ‰๊ฐ€ ์‹œ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ์€ ํ”ผ๋กœ์— ๋Œ€ํ•œ ์†์ƒ์„ ์‹ค์ œ๋ณด๋‹ค 2.5๋ฐฐ, Shell-Solid ํ•ด์„๋ชจ๋ธ์€ 3๋ฐฐ๊ฐ€๋Ÿ‰ ๋ณด์ˆ˜์ ์œผ๋กœ ํ‰๊ฐ€ํ•˜๊ฒŒ ๋œ๋‹ค. ํ•˜์ง€๋งŒ, BWIM ๋ฐ์ดํ„ฐ์˜ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•œ ์‹œ๊ณ„์—ด ์‘๋ ฅ์ด๋ ฅ์„ ํ†ตํ•ด ์‹ ๋ขฐ๋„ํ‰๊ฐ€๋ฅผ ์ˆ˜ํ–‰ํ•  ๊ฒฝ์šฐ ๋ผˆ๋Œ€์š”์†Œ ํ•ด์„๋ชจ๋ธ์€ 1.5๋ฐฐ, Shell-Solid ํ•ด์„๋ชจ๋ธ์€ ์•ฝ 1.1๋ฐฐ ์ˆ˜์ค€์œผ๋กœ, ๋ณด๋‹ค ์‹ค์ œ์— ๊ฐ€๊นŒ์šด ํ‰๊ฐ€๊ฐ€ ๊ฐ€๋Šฅํ•จ์„ ํ™•์ธํ•˜์˜€๋‹ค.

๋”ฐ๋ผ์„œ, ๊ต๋Ÿ‰์˜ ํ”ผ๋กœ ์‹ ๋ขฐ๋„ํ‰๊ฐ€ ์‹œ ํ™œ์šฉ๋˜๋Š” ๊ตฌ์กฐํ•ด์„๋ชจ๋ธ์˜ ์ •๋ฐ€์„ฑ๊ณผ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์ด ๊ต๋Ÿ‰์˜ ํ‰๊ฐ€ ํ”ผ๋กœ ์ˆ˜๋ช…์— ํฌ๊ฒŒ ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ์š”์†Œ์ž„์„ ๋ณด์˜€๋‹ค. ํŠนํžˆ, ์‹ค์ œ์— ๊ฐ€๊นŒ์šด ํ‰๊ฐ€๋ฅผ ์œ„ํ•ด์„œ๋Š” BWIM ๊ณ„์ธก ๋ฐ์ดํ„ฐ๋ฅผ ์ฒ˜๋ฆฌํ•˜๋Š” ๊ณผ์ •์—์„œ ์ฃผํ–‰ ํŒจํ„ด ํŠน์„ฑ์ด ๋ฐ˜๋“œ์‹œ ๊ณ ๋ ค๋˜์–ด์•ผ ํ•จ์„ ํ‰๊ฐ€๊ฒฐ๊ณผ๋“ค ๋ฐ”ํƒ•์œผ๋กœ ์ž…์ฆํ•˜์˜€๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

์ด ์—ฐ๊ตฌ๋Š” ์„œ์šธ๋Œ€ํ•™๊ต ๊ฑด์„คํ™˜๊ฒฝ์ข…ํ•ฉ์—ฐ๊ตฌ์†Œ๋ฅผ ํ†ตํ•ด ์ง€์›๋œ ๊ตญํ† ๊ตํ†ต๋ถ€ ๊ฑด์„ค๊ธฐ์ˆ ์—ฐ๊ตฌ๊ฐœ๋ฐœ์‚ฌ์—…์˜ ์—ฐ๊ตฌ๋น„ ์ง€์›(21SCIP-B128568- 05)์— ์˜ํ•ด ์ˆ˜ํ–‰๋˜์—ˆ์Šต๋‹ˆ๋‹ค. ์ด์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

๋ณธ ๋…ผ๋ฌธ์€ 2021 CONVENTION ๋…ผ๋ฌธ์„ ์ˆ˜์ •ยท๋ณด์™„ํ•˜์—ฌ ์ž‘์„ฑ๋˜์—ˆ์Šต๋‹ˆ๋‹ค.

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