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๊ฐ•์„ฌ์œ ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ(UHPFRC), ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„, ์‘๋ ฅ ์žฌ๋ถ„๋ฐฐ, ํŒŒ๊ดด ๋ชจ๋“œ, ์ „๋‹จ ๊ฐ•๋„
UHPFRC, material tensile strength, stress redistribution, failure mode, shear strength

  • 1. ์„œ ๋ก 

  • 2. ์‹ค ํ—˜

  •   2.1 ์‹คํ—˜ ๋ณ€์ˆ˜ ๋ฐ ๋ถ€์žฌ ์ƒ์„ธ

  •   2.2 ๊ฐ€๋ ฅ ๋ฐ ๊ณ„์ธก ๊ณ„ํš

  •   2.3 ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„ ์‹คํ—˜ ๊ณ„ํš ๋ฐ ๊ฒฐ๊ณผ

  • 3. ์‹คํ—˜ ๊ฒฐ๊ณผ ๋ฐ ๋ถ„์„

  •   3.1 ์‹คํ—˜๋ณ€์ˆ˜์— ๋”ฐ๋ฅธ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„

  •     3.1.1 ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„(a/d)์— ๋”ฐ๋ฅธ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„

  •     3.1.2 ์œ ํšจ๋†’์ด(d)์— ๋”ฐ๋ฅธ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„

  •   3.2 ๊ท ์—ด ์–‘์ƒ ๋ฐ ํŒŒ๊ดด ๋ชจ๋“œ

  •   3.3 ๋ณต๋ถ€ ์ฃผ์ธ์žฅ ๊ฐ๋„ ๋ฐ ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ ๊ตฌ๊ฐ„

  • 4. ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์˜์ „๋‹จ๊ฐ•๋„ ํ‰๊ฐ€

  •   4.1 UHPFRC ์ „๋‹จ ๊ฐ•๋„ ํ‰๊ฐ€์‹

  •     4.1.1 Recommendations for Design and Construction for UHPC, AFGC Setra

  •     4.1.2 fib model code 2010 / DIN EN 1992-1-1

  •     4.1.3 Sato, et. al. (TU Delft)

  •   4.2 UHPFRC ์ „๋‹จ ๊ฐ•๋„ ํ‰๊ฐ€์‹๊ณผ ์‹คํ—˜๊ฒฐ๊ณผ ๋น„๊ต

  • 5. ๊ฒฐ ๋ก 

1. ์„œ    ๋ก 

์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ(UHPC)๋Š” ๊ณต๊ทน์ด ์ž‘๊ณ  ๋ฐ€์‹คํ•˜๋ฉฐ ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ์— ๋น„ํ•ด ๊ท ์งˆํ•˜๊ณ  ์ž๊ธฐ ๋‹ค์งํšจ๊ณผ๊ฐ€ ๋›ฐ์–ด๋‚˜ ์‹œ๊ณต์„ฑ ๋ฐ ์„ฑํ˜•์„ฑ์ด ์šฐ์ˆ˜ํ•˜๋‹ค. ๋˜ํ•œ 150MPa ์ด์ƒ์˜ ๋†’์€ ์••์ถ•๊ฐ•๋„ ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๋‚ด๋งˆ๋ชจ์„ฑ, ๋‚ด๊ท ์—ด์„ฑ ๋“ฑ ๋‚ด๊ตฌ์„ฑ๋Šฅ์ด ๋›ฐ์–ด๋‚˜ ๊ตฌ์กฐ๋ฌผ์— ์ ์šฉ ์‹œ ์œ ์ง€, ๋ณด์ˆ˜์— ์ด์ ์ด ์žˆ๋‹ค.1) ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ(UHPFRC)๋Š” ์—ฌ๊ธฐ์— ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•์— ์˜ํ•œ ๊ท ์—ด ํ›„ ์ž”์—ฌ๊ฐ•๋„๊ฐ€ ํฐ ํŠน์ง•์„ ๊ฐ€์ง„๋‹ค. ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์„ค๊ณ„์—์„œ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ธ์žฅ๊ฐ•๋„๋ฅผ ๊ณ ๋ คํ•˜์ง€ ์•Š๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด์ง€๋งŒ, UHPFRC๋Š” ๊ท ์—ด ๋ฐœ์ƒ ํ›„์—๋„ ๊ฐ•์„ฌ์œ ์™€ ๋งคํŠธ๋ฆญ์Šค ๊ฐ„์˜ ๋ถ€์ฐฉ์‘๋ ฅ์— ์˜ํ•œ ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ ํšจ๊ณผ๊ฐ€ ๋›ฐ์–ด๋‚˜ ์ž”๊ท ์—ด์ด ๋„“๊ฒŒ ๋ถ„์‚ฐ๋˜๋ฉฐ ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„๊ฐ€ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์—ฌ ์ธ์žฅ๊ฐ•๋„๋ฅผ ๋ถ€์žฌ์„ค๊ณ„ ์‹œ ๊ณ ๋ คํ•˜๋Š” ๊ฒƒ์ด ํ•ฉ๋ฆฌ์ ์ด๋‹ค.1-5) ์žฌ๋ฃŒ์˜ ์‘๋ ฅ๋ถ„์‚ฐํšจ๊ณผ๊ฐ€ ๋›ฐ์–ด๋‚˜๊ณ  ๊ฐ•์„ฑ์ด ํฌ๊ธฐ ๋•Œ๋ฌธ์— ๋ฉด๋‚ด ์ „๋‹จ๊ฑฐ๋™์— ์œ ๋ฆฌํ•œ ์žฅ์ ์ด ์žˆ์–ด ๋‘๊ป˜๊ฐ€ ์–‡๊ณ  ๊ตฌ์กฐ์ ์œผ๋กœ ์ตœ์ ํ™”๋œ ๋‹จ๋ฉด์„ ๊ฐ€์ง„ ๋ถ€์žฌ์˜ ์„ค๊ณ„๊ฐ€ ๊ฐ€๋Šฅํ•˜๋‹ค. ์ด๋Ÿฌํ•œ ์žฅ์ ์„ ํ™œ์šฉํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ผ๋ฐ˜์ฒ ๊ทผ์˜ ๋ฐฐ๊ทผ์„ ์ตœ์†Œํ™”ํ•˜๊ณ , ๊ฐ•์„ฌ์œ ์— ์˜ํ•œ ์ „๋‹จ๋ณด๊ฐ•ํšจ๊ณผ๋ฅผ ํ•ฉ๋ฆฌ์ ์œผ๋กœ ์˜ˆ์ธกํ•˜์—ฌ ์„ค๊ณ„๋ฅผ ํ•˜๋Š” ๊ฒƒ์ด ์ค‘์š”ํ•˜๋‹ค.

UHPFRC ๋ณด์˜ ์ „๋‹จ ๊ฑฐ๋™์— ๋Œ€ํ•œ ์‹คํ—˜์—ฐ๊ตฌ๋Š” ๊ฒฝ์ œ์„ฑ๊ณผ ์‹œ๊ณตํŽธ์˜์„ฑ, ๋›ฐ์–ด๋‚œ ๊ตฌ์กฐ์  ์„ฑ๋Šฅ์„ ๊ณ ๋ คํ•˜์—ฌ ๋ณต๋ถ€ ๋‘๊ป˜๋ฅผ ์ค„์ธ Iํ˜• ๋‹จ๋ฉด์— ๋ณต๋ถ€ ๋‘๊ป˜๋Š” 40~65mm๋กœ ๋‘๊ป˜๊ฐ€ ์–‡๊ณ  ์ „๋‹จ์ฒ ๊ทผ์„ ๋ฐฐ๊ทผํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ๊ฐ€ ๋Œ€๋ถ€๋ถ„์ด๋‹ค. Yang et al. (2012),2) Voo and Foster (2010),3) Hegger and Betram (2008)4)์€ ์ „๋‹จ ์ฒ ๊ทผ์ด ์—†๋Š” Iํ˜• ๋ณด์— ๋Œ€ํ•ด ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„์™€ ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„๋ฅผ ์ฃผ์š” ๋ณ€์ˆ˜๋กœ ์‹คํ—˜ํ•˜์˜€์œผ๋ฉฐ, ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„๊ฐ€ ์ปค์งˆ์ˆ˜๋ก ์ „๋‹จ๊ฐ•๋„๋Š” ๋šœ๋ ทํ•˜๊ฒŒ ์ฆ๊ฐ€ํ•˜๊ณ  ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ ์ปค์งˆ์ˆ˜๋ก ์ „๋‹จ๊ฐ•๋„๋Š” ๊ฐ์†Œํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์ธ๋‹ค๊ณ  ๋ณด๊ณ ํ•˜์˜€๋‹ค. ์ƒ๊ธฐ ์—ฐ๊ตฌ์—์„œ ๋ชจ๋“  ์‹คํ—˜์ฒด์˜ ์ตœ์ข… ํŒŒ๊ดด๋Š” ๋ณต๋ถ€ ๊ท ์—ด ์ง‘์ค‘ ํ˜„์ƒ์— ์˜ํ•œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋ฅผ ๋ณด์˜€๋‹ค. Baby et al. (2014)5)์€ Iํ˜• ๋ณด๋ฅผ ํ˜ผ์ž… ์„ฌ์œ  ์ข…๋ฅ˜์— ๋”ฐ๋ผ ์ผ๋ฐ˜์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•˜์—ฌ ์ „๋‹จ๋ณด๊ฐ•ํ•œ ๊ฒฝ์šฐ์™€ ์ „๋‹จ๋ณด๊ฐ•ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ, ํ”„๋ ˆ์ŠคํŠธ๋ ˆ์Šค๋ฅผ ์ค€ ๊ฒฝ์šฐ์™€ ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์Šค๋ฅผ ์ฃผ์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•ด 4์  ์žฌํ•˜ ์‹คํ—˜์„ ํ•˜์˜€๋Š”๋ฐ, ์ „๋‹จ๊ฐ•๋„ ๋ฐ ๊ฑฐ๋™์—๋Š” ์ฐจ์ด๊ฐ€ ์žˆ์œผ๋‚˜ ํŒŒ๊ดด๋ชจ๋“œ๋Š” ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์— ์˜ํ•œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋กœ ๋™์ผํ•˜์˜€๋‹ค. ์ฆ‰, ์ „๋‹จ๋ณด๊ฐ•๊ทผ์„ ๋ฐฐ๊ทผํ•œ ๊ฒฝ์šฐ๋„ ์ „๋‹จ ๋ณด๊ฐ•๊ทผ ํ•ญ๋ณต ํ›„ ๋ณต๋ถ€ ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์— ์˜ํ•ด ์ตœ๋Œ€๊ฐ•๋„์— ๋„๋‹ฌํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ „๋‹จ๋ณด์—์„œ ๊ท ์—ด์ง‘์ค‘ํ˜„์ƒ์— ์˜ํ•œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋Š” ํœจ ์‹คํ—˜์—์„œ ๊ท ์—ด์ด ์ธ์žฅ๋‹จ์— ๊ณ ๋ฅด๊ฒŒ ํผ์ง„ ํ›„ ํœจ์ฒ ๊ทผ ํ•ญ๋ณต์— ์˜ํ•ด ์ตœ๋Œ€๊ฐ•๋„์— ๋„๋‹ฌํ•˜์ง€ ์•Š๊ณ , ์ธ์žฅ ์ฃผ์ฒ ๊ทผ ํ•ญ๋ณต ํ›„ ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘์— ์˜ํ•ด ์ตœ๋Œ€ ๊ฐ•๋„๊ฐ€ ๊ฒฐ์ •6)๋˜๋Š” ๊ฒƒ๊ณผ ๊ฐ™์€ ๋งฅ๋ฝ์—์„œ ์ดํ•ดํ•  ์ˆ˜ ์žˆ๋‹ค. Redaelli D. (2006)7)๋Š” ์ฒ ๊ทผ์ด ๋ฐฐ๊ทผ๋œ UHPFRC์˜ ์ง์„ ๋ถ€์žฌ ์ธ์žฅ์‹คํ—˜์„ ํ†ตํ•ด ์ฒ ๊ทผ๊ณผ UHPFRC์˜ ํฐ ๋ถ€์ฐฉ์‘๋ ฅ7,8)์œผ๋กœ ์ธํ•ด ์ผ๋ฐ˜ ์ฒ ๊ทผ์˜ ์‚ฌ์šฉ์œผ๋กœ๋Š” ๊ทนํ•œ ํ•œ๊ณ„ ์ƒํƒœ์—์„œ ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์„ ํ”ผํ•˜๊ธฐ ํž˜๋“ค๋‹ค๊ณ  ์ง€์ ํ•œ ๋ฐ” ์žˆ์œผ๋ฉฐ, ์ธ์žฅ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด๋Š” UHPFRC์˜ ๊ฒฝ์šฐ ๊ทนํ•œ ๋ณ€ํ˜•๋ฅ ์ด 0.0025์ด์ƒ์ด๋ฉฐ ์ด ๊ฐ’์ด ์ผ๋ฐ˜์ ์œผ๋กœ ์‚ฌ์šฉ๋˜๋Š” SD400 ์ฒ ๊ทผ์˜ ํ•ญ๋ณต ๋ณ€ํ˜•๋ฅ  0.002๋ณด๋‹ค ํฌ๋‹ค๋Š” ์ ๋„ ์ฐธ๊ณ ํ• ๋งŒ ํ•˜๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ๋Š” UHPFRC ์ „๋‹จ๋ณด์˜ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด์— ๋Œ€ํ•œ ๊ฑฐ๋™์„ ๋ถ„์„ํ•˜๋Š” ๊ฒƒ์„ ๋ชฉํ‘œ๋กœ, ์—ฐ๊ตฌ์˜ ํšจ์œจ์  ์ˆ˜ํ–‰์„ ์œ„ํ•ด ๋‹จ๋ฉด ๋‘๊ป˜๊ฐ€ ์–‡๊ณ  ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” Iํ˜• UHPFRC ๋ณด๋กœ ์—ฐ๊ตฌ๋‚ด์šฉ์„ ๊ตญํ•œํ•˜์˜€๋‹ค.

UHPFRC ๋ณด์˜ ์ „๋‹จ์„ค๊ณ„ ์‹œ ์‚ฌ์ธ์žฅ ๊ท ์—ด์—์„œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ์— ๋Œ€ํ•œ ๋ถ„์„์„ ์œ„ํ•ด์„œ๋Š” ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ(SFRC)์˜ ๊ฐ•์„ฌ์œ ์˜ ์ „๋‹จ๊ฐ•๋„ ๊ธฐ์—ฌ๋ถ„์— ๋Œ€ํ•œ ์—ญํ•™์  ๊ธฐ์ œ๋ฅผ ๊ฒ€ํ† ํ•  ํ•„์š”๊ฐ€ ์žˆ๋‹ค. Fig. 1์€ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ๋กœ์„œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด ์‹œ ์ฃผ๊ท ์—ด์—์„œ ์ž”๋ฅ˜ ์ธ์žฅ๊ฐ•๋„๋ฅผ ๊ณ ๋ คํ•œ SFRC ์ „๋‹จ์ €ํ•ญ๋ชจ๋ธ9)๋กœ ์‹ (1)๊ณผ ๊ฐ™์ด ํ‘œํ˜„๋œ๋‹ค.

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/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F1.jpg

Fig. 1 Crack geometry relative to the shear behavior of a SFRC beam (Casanova and Rossi,1997)9)

์‚ฌ์ธ์žฅ ๊ท ์—ด ๊ฐ๋„๋Š” 45ยฐ๋กœ ๊ฐ€์ •ํ•˜์˜€์œผ๋ฉฐ, ๋ถ€์žฌ๊ฐ€ ๊ท ์—ด์„ ๋”ฐ๋ผ ๋ฐœ์ƒํ•˜๋Š” ์ž”๋ฅ˜์ธ์žฅ์‘๋ ฅ /Resources/kci/JKCI.2017.29.1.053/images/PIC9E66.gif์— ์˜ํ•ด ์ €ํ•ญํ•˜๋‹ค๊ฐ€ ๋ถ€์žฌ ํ•˜๋ถ€์—์„œ ์ฃผ๊ท ์—ด์˜ ํญ์ด ์ตœ๋Œ€ ๊ท ์—ดํญ /Resources/kci/JKCI.2017.29.1.053/images/PIC9EA6.gif์ด ๋˜๋ฉด ๋ถ€์žฌ๊ฐ€ ์ตœ๋Œ€๊ฐ•๋„์— ๋„๋‹ฌํ•˜๋Š” ๊ฒƒ์œผ๋กœ ์„ค๋ช…ํ•˜๊ณ  ์žˆ๋‹ค. ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋ชจ๋“œ์—์„œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•์— ์˜ํ•œ ์ „๋‹จ์ €ํ•ญ ๊ธฐ์ œ๋Š” UHPFRC์—๋„ ๋น„์Šทํ•œ ๊ฐœ๋…์œผ๋กœ ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ SFRC๋Š” ๊ตต์€ ๊ณจ์žฌ๋ฅผ ํฌํ•จํ•˜๋Š” ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์— ์–‘๋‹จ๊ณ ๋ฆฌํ˜• ๊ฐ•์„ฌ์œ ๋ฅผ ์‚ฌ์šฉํ•˜๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด๋ฉฐ, ๊ตต์€ ๊ณจ์žฌ๋กœ ์ธํ•ด ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•๋น„๋ฅผ ์ฆ๊ฐ€์‹œํ‚ค๋Š”๋ฐ ํ•œ๊ณ„๊ฐ€ ์žˆ์–ด ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„๊ฐ€ 0.75% ๋‚ด์™ธ๋กœ ํฌ์ง€ ์•Š๊ณ  ๊ท ์—ด ํ›„ ์ž”์—ฌ์ธ์žฅ๊ฑฐ๋™์ด ์—ฐํ™”๊ฑฐ๋™์œผ๋กœ ์ •์˜๋˜๋Š” ์ฐจ์ด๊ฐ€ ์žˆ๋‹ค.10,11) UHPFRC๋Š” ๊ตต์€ ๊ณจ์žฌ ์—†์ด ๊ณต๊ทน์ด ์ž‘์€ ๊ท ์งˆํ•œ ๋งคํŠธ๋ฆญ์Šค์— ์ธ์žฅ๊ฐ•๋„๊ฐ€ ์•ฝ 2400MPa์— ์ด๋ฅด๋Š” ๊ณ ๊ฐ•๋„ ์ง์„ ํ˜• ๊ฐ•์„ฌ์œ ๋ฅผ 1.5% ์ด์ƒ ํ˜ผ์ž…ํ•˜๋ฉฐ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ๋ฅผ ์ ๊ทน์ ์œผ๋กœ ํ™œ์šฉํ•  ์ˆ˜ ์žˆ๋Š” ์žฌ๋ฃŒ์ด๋‹ค. ๊ธฐ์กด ๋ชจ๋ธ์€ ์ธ์žฅ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด์ง€ ์•Š๋Š” SFRC ์ง์‚ฌ๊ฐํ˜• ๋‹จ๋ฉด ๋ถ€์žฌ์—์„œ๋Š” ์œ ํšจํ•˜๋‚˜, UHPFRC์™€ ๊ฐ™์ด ๊ท ์—ด ํ›„ ๋ฏธ์„ธ๊ท ์—ด์˜ ํ™•์žฅ์— ์˜ํ•œ ์ธ์žฅ๊ฒฝํ™”๊ฑฐ๋™์ด ์ง€๋ฐฐ์ ์ธ ๋ถ€์žฌ์˜ ๊ฑฐ๋™์„ ์„ค๋ช…ํ•˜๋Š”๋ฐ ํ•œ๊ณ„๊ฐ€ ์žˆ๋‹ค. ๋˜ํ•œ ๋ณธ ์—ฐ๊ตฌ์˜ ์‹คํ—˜์ฒด ๋ณต๋ถ€์™€ ๊ฐ™์ด ์‘๋ ฅ์žฅ์ด ๊ท ์ผํ•˜๊ฒŒ ํ˜•์„ฑ๋˜๋Š” ๋ฉด๋‚ด์ „๋‹จ๊ฑฐ๋™์— ๋Œ€ํ•ด์„œ๋Š” ์ ํ•ฉํ•˜์ง€ ์•Š๋‹ค.

UHPFRC ๊ตฌ์กฐ ์„ค๊ณ„๋Š” ํ”„๋ž‘์Šค ํ† ๋ชฉํ•™ํšŒ(AFGC)์—์„œ ๋ฐœ๊ฐ„ํ•œ ์ง€์นจ12)์ด ๊ฐ€์žฅ ๋งŽ์ด ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋Š”๋ฐ, ์ด ์ค‘ ์ „๋‹จ ๊ฐ•๋„ ์„ค๊ณ„์‹์€ ๋งคํŠธ๋ฆญ์Šค์— ์˜ํ•œ ๊ฐ•๋„์™€ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•์— ์˜ํ•œ ๊ฐ•๋„ ์ฆ๊ฐ€๋ถ„์— ๋Œ€ํ•ด ๋ณ„๋„์˜ ํ•ญ์œผ๋กœ ์ •๋ฆฌํ•˜์—ฌ ๋‘˜์˜ ํ•ฉ์œผ๋กœ ์ •์˜ํ•˜๊ณ  ์žˆ์œผ๋‚˜ ์ด์— ๋Œ€ํ•œ ์‹คํ—˜์  ๊ทผ๊ฑฐ ๋ฐ ์ด๋ก ์  ๋ฐฐ๊ฒฝ์€ ๋ฏธ์•ฝํ•˜๋‹ค. AFGC ์ง€์นจ์—์„œ๋Š” ์‹ (1)์„ UHPFRC์—์„œ ๊ฐ•์„ฌ์œ  ์ „๋‹จ ๊ธฐ์—ฌ๋ถ„์œผ๋กœ ์ •์˜ํ•˜๋˜, ์‚ฌ์ธ์žฅ ๊ท ์—ด์˜ ๊ฐ๋„๋Š” 45ยฐ๊ฐ€ ์•„๋‹Œ ๋ณต๋ถ€์—์„œ ์ฃผ์‘๋ ฅ๋ฐฉํ–ฅ /Resources/kci/JKCI.2017.29.1.053/images/PIC9EC6.gif๋กœ ์ •์˜ํ•˜์—ฌ ์ด๋ฅผ ๋ณ„๋„๋กœ ๊ณ ๋ คํ•˜๊ณ  ์žˆ๋‹ค.

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” UHPFRC Iํ˜• ๋ณด์˜ ๊ท ์—ด๋ฐœ์ƒ ์ดํ›„ ์ „๋‹จ๊ฑฐ๋™์˜ ์‘๋ ฅ ์žฌ๋ถ„๋ฐฐํšจ๊ณผ๋ฅผ ์ •๋Ÿ‰์ ์œผ๋กœ ํŒ๋‹จํ•˜๊ณ , ๊ท ์—ด ํ›„ ๊ฑฐ๋™์„ ๊ธฐ์กด ์ „๋‹จ ๊ฐ•๋„์‹์ด ์ž˜ ๋ฐ˜์˜ํ•˜๊ณ  ์žˆ๋Š”์ง€ ๊ฒ€ํ† ํ•˜์˜€๋‹ค. ํŠนํžˆ ์ „๋‹จ ๊ฐ•๋„ ์‚ฐ์ • ์‹œ ๊ฐ•์„ฌ์œ  ๊ธฐ์—ฌ๋ถ„์˜ ์ฃผ์š” ๋ณ€์ˆ˜์ธ ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„ ์ •์˜์— ๋Œ€ํ•ด ๊ณ ์ฐฐํ•˜๊ณ , ๋ณต๋ถ€ ์ฃผ์‘๋ ฅ๋ฐฉํ–ฅ์— ๋Œ€ํ•œ ์‹คํ—˜์  ๊ทผ๊ฑฐ๋ฅผ ์ œ์‹œํ•˜์—ฌ UHPFRC ๋ถ€์žฌ ์ „๋‹จ๊ฑฐ๋™ ํŠน์„ฑ์„ ์•Œ์•„๋ณด๊ณ ์ž ํ•œ๋‹ค.

2. ์‹คํ—˜ ๊ณ„ํš

2.1 ์‹คํ—˜ ๋ณ€์ˆ˜ ๋ฐ ๋ถ€์žฌ ์ƒ์„ธ

UHPFRC Iํ˜• ๋ณด์˜ ์ตœ์ข… ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋กœ ๊ฐ€์ •ํ•˜๊ณ , ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์—์„œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด์— ์˜ํ–ฅ์„ ๋ผ์น˜๋Š” ๊ฒƒ์œผ๋กœ ์•Œ๋ ค์ง„ ์ธ์ž๋ฅผ ์‹คํ—˜ ๋ณ€์ˆ˜๋กœ ์ •ํ•˜์˜€๋‹ค. ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„๊ฐ€ ๋‹ค๋ฅธ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ฐฐํ•ฉ 3์ข… 1, 2, 3์— ๋Œ€ํ•˜์—ฌ ๊ฐ๊ฐ ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„(/Resources/kci/JKCI.2017.29.1.053/images/PIC9F34.gif)์™€ ํฌ๊ธฐํšจ๊ณผ(/Resources/kci/JKCI.2017.29.1.053/images/PIC9F55.gif)๋ฅผ ์‹คํ—˜๋ณ€์ˆ˜๋กœ ์ด 9๊ฐœ์˜ ์‹คํ—˜์ฒด๋ฅผ ์ œ์ž‘ํ•˜์˜€๋‹ค. ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„์™€ ํฌ๊ธฐํšจ๊ณผ๋Š” ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋ฅผ ๋ณด์ด๋Š” ๋ถ€์žฌ์—์„œ ์ค‘์š”ํ•˜๊ฒŒ ๊ณ ๋ ค๋˜๋Š” ๋ณ€์ˆ˜์ด๋ฉฐ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ํŠน์ง•์„ ๊ฐ€์ง„๋‹ค. ๋จผ์ €, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๋Š” ๋ณด ๋ณต๋ถ€์— ์ž‘์šฉํ•˜๋Š” ์‘๋ ฅ์žฅ์˜ ํ˜•ํƒœ๋ฅผ ๊ฒฐ์ •ํ•œ๋‹ค. ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ ์ž‘์€ ๊ฒฝ์šฐ๋Š” ์•„์น˜ํšจ๊ณผ์— ์˜ํ•ด ๊ฐ€๋ ฅ๋ถ€์™€ ์ง€์ ์— ๋‹จ์ผ ์ŠคํŠธ๋Ÿฟ์ด ๋ฐœ์ƒํ•  ๊ฐ€๋Šฅ์„ฑ์ด ํฐ ๋ฐ˜๋ฉด, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ ์ปค์งˆ์ˆ˜๋ก ํœจ ๊ฑฐ๋™์ด ์ง€๋ฐฐํ•˜๊ฒŒ ๋˜๋ฉฐ ๋ณต๋ถ€ ๋‚ด์— ๊ท ์ผํ•œ ์‘๋ ฅ์žฅ์ด ํ˜•์„ฑ๋˜๊ฒŒ ๋œ๋‹ค. ํ•œํŽธ, ํฌ๊ธฐํšจ๊ณผ๋Š” ์ทจ์„ฑ ํŒŒ๊ดด๋ฅผ ๋ณด์ด๋Š” ๋ถ€์žฌ์— ๋‚˜ํƒ€๋‚˜๋Š” ํ˜„์ƒ์œผ๋กœ์จ ์ผ๋ฐ˜์ ์œผ๋กœ ์ „๋‹จ์ฒ ๊ทผ์„ ๋ฐฐ๊ทผํ•œ ๋ถ€์žฌ์—์„œ๋Š” ๊ณ ๋ คํ•˜์ง€ ์•Š์œผ๋‚˜ ๋ณธ ์‹คํ—˜์—์„œ๋Š” ์‹คํ—˜์ฒด์˜ ํŒŒ๊ดด๋ชจ๋“œ๊ฐ€ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋ผ๋Š” ๊ฐ€์ • ํ•˜์— ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์ด ์ทจ์„ฑ์  ํŒŒ๊ดด์ž„์„ ๊ณ ๋ คํ•˜์—ฌ ์œ ํšจ ๋†’์ด๋ฅผ ๋ณ€์ˆ˜๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค. ๋ฐฐํ•ฉ 3์ข…์€ Table 1๊ณผ ๊ฐ™์œผ๋ฉฐ ๋งคํŠธ๋ฆญ์Šค ๋ฐฐํ•ฉ์€ ์œ ์‚ฌํ•˜๊ณ , ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„์— ์ฐจ์ด๊ฐ€ ์žˆ๋‹ค. ์ง์„ ํ˜•์ƒ ๊ฐ•์„ฌ์œ  16mm์™€ 20mm๋ฅผ 1:2 ๋น„์œจ์„ ์œ ์ง€ํ•˜๋ฉด์„œ ๋ฐฐํ•ฉ 1, 2๋Š” ๋ถ€ํ”ผ๋น„ 1.5%, ๋ฐฐํ•ฉ 3์€ ๋ถ€ํ”ผ๋น„ 1.0%๋กœ ๊ณ„ํšํ•˜์˜€๋‹ค. ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ธ์žฅ๊ฑฐ๋™ ํŠน์„ฑ13)์€ Fig. 2์™€ ๊ฐ™์ด ๊ตฌ๋ถ„ํ•˜์—ฌ ์„ค๋ช…ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ง์ ‘์ธ์žฅ ์‹คํ—˜์œผ๋กœ ์ธ์žฅ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ, ํœจ์ธ์žฅ ์‹คํ—˜์œผ๋กœ๋Š” ํœจ๊ฐ•๋„-์ฒ˜์ง ๊ด€๊ณ„๋ฅผ ์ •์˜ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ง์ ‘์ธ์žฅ์‹คํ—˜๊ฒฐ๊ณผ ์ธ์žฅ์—ฐํ™”๊ฑฐ๋™์„ ๋ณด์ด๋Š” ๊ฒฝ์šฐ๋Š” ํœจ์ธ์žฅ ๊ฑฐ๋™์—์„œ๋Š” ๊ท ์—ด ๋ฐœ์ƒ ํ›„ ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ผ์ˆ˜๋„, ์—ฐํ™”๊ฑฐ๋™์„ ๋ณด์ผ ์ˆ˜๋„ ์žˆ๋Š”๋ฐ, ์ด๋Ÿฌํ•œ ์žฌ๋ฃŒ์ธ์žฅ๊ฑฐ๋™ ๋ฐ ๊ตฌ์กฐ์ธ์žฅ๊ฑฐ๋™์€ ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„์— ์˜ํ•ด ํฌ๊ฒŒ ์ง€๋ฐฐ๋ฐ›๋Š” ๊ฒƒ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์žฌ๋ฃŒ์ธ์žฅ๊ฑฐ๋™ ๋ฐ ๋ถ€์žฌ์ธ์žฅ๊ฑฐ๋™์—์„œ ์ฐจ์ด๊ฐ€ ์žˆ๋Š” ์žฌ๋ฃŒ ๋ฐฐํ•ฉ์— ๋”ฐ๋ฅธ ๋ณด ์ „๋‹จ๊ฑฐ๋™์„ ์•Œ์•„๋ณด๊ณ ์ž ํ•˜์˜€๋‹ค.

Table 1 Mix proportion (in mass ratio)

/Resources/kci/JKCI.2017.29.1.053/images/Table_CONCRETE_29_01_06_T1.jpg

* B (premix Binder): cement, Zr, BS, filler, expansion agent, shrinkage reducing agent premix

* A (fine Aggregates), SF (Steel Fiber), S (Superplasticizer), G (air-entraining aGent)

/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F2.jpg

Fig. 2 Classification of FRC composites based on their tensile response (Naaman et al.,2003)13)

๋ฐฐํ•ฉ๋ณ„ ์‹คํ—˜์ฒด๋Š” Fig. 3๊ณผ ๊ฐ™๋‹ค. ์œ ํšจ๋†’์ด๊ฐ€ 445mm์ธ ๊ฒฝ์šฐ์— ๋Œ€ํ•ด ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„ 2.5์™€ 3.5๋ฅผ ๋ณ€์ˆ˜๋กœ ๋‘๊ณ , ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ธ ๊ฒฝ์šฐ์— ๋Œ€ํ•ด ์œ ํšจ๋†’์ด๊ฐ€ 445mm์™€ 625mm๋ฅผ ๋ณ€์ˆ˜๋กœ ํ•˜์˜€๋‹ค. ๋ณต๋ถ€๋‘๊ป˜ /Resources/kci/JKCI.2017.29.1.053/images/PIC9FA4.gif๋Š” 40mm๋กœ ์ผ์ •ํ•˜๋‹ค. ๋ณต๋ถ€๋‘๊ป˜๋Š” ๋ณดํ†ต ์ฝ˜ํฌ๋ฆฌํŠธ ๋‹จ๋ฉด์— ๋น„ํ•ด ๋งค์šฐ ์–‡๊ฒŒ ์„ค๊ณ„๋˜์—ˆ๋Š”๋ฐ, ์ด๋Š” ์žฌ๋ฃŒ์˜ ๊ฒฝ์ œ์„ฑ์„ ๊ณ ๋ คํ•˜์—ฌ ์ „๋‹จ ๋ถ€์žฌ๊ฐ€ ์ „๋‹จ ์ฒ ๊ทผ ์—†์ด ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•๋งŒ์œผ๋กœ ์ถฉ๋ถ„ํžˆ ์ „๋‹จ๋ ฅ์— ์ €ํ•ญํ•˜๋Š” ๊ฒฝ์šฐ, ๊ฐ€๋Šฅํ•œ ๋ณต๋ถ€ ํญ์„ ์ž‘๊ฒŒ ์„ค๊ณ„ํ•˜์—ฌ ์ตœ์†Œ๋‘๊ป˜ ํญ์— ๋Œ€ํ•œ ์‹คํ—˜์  ๊ทผ๊ฑฐ๋ฅผ ์ œ์‹œํ•˜๊ธฐ ์œ„ํ•จ์ด๋‹ค. Iํ˜• ๋‹จ๋ฉด ๋ณต๋ถ€๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๋ฐฐํ•ฉ์— ๋”ฐ๋ผ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•์— ์˜ํ•œ ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„์— ์˜ํ•ด ์ง€์ง€๋˜๋„๋ก ํ•˜์˜€์œผ๋ฉฐ, ํœจ ์ฒ ๊ทผ์€ ์ถฉ๋ถ„ํžˆ ๋ฐฐ๊ทผํ•˜์—ฌ ๋ณต๋ถ€ ์ „๋‹จํŒŒ๊ดด๊ฐ€ ์ผ์–ด๋‚˜๋„๋ก ์„ค๊ณ„ํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F3.jpg

Fig. 3 Details of test specimens and measurement program

2.2 ๊ฐ€๋ ฅ ๋ฐ ๊ณ„์ธก ๊ณ„ํš

100ton ์•ก์ธ„์—์ดํ„ฐ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ๋ณ€์œ„์ œ์–ด๋กœ 3์  ์ •์  ์žฌํ•˜ ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ๊ฐ€๋ ฅ๋ถ€ ๋ฐ ์ง€์  ์žฌํ•˜ํŒ์€ ํญ 150mm์— ๊ฑธ์ณ ๋ณด ์ƒยทํ•˜๋ถ€ ํ”Œ๋žœ์ง€ ๋„ˆ๋น„๋ฅผ ๋ชจ๋‘ ํฌํ•จํ•˜๋„๋ก ํ•˜์˜€๋‹ค. ๊ฐ€๋ ฅ ๋ฐ ๊ณ„์ธก ๊ณ„ํš์€ Fig. 3๊ณผ ๊ฐ™๋‹ค. ๊ณ„์ธก ๊ณ„ํš์€ ๊ฐ€๋ ฅ๋ถ€ ์ˆ˜์ง๋ณ€ํ˜• ์™ธ์— ๋ณต๋ถ€ ์ „๋‹จ๋ณ€ํ˜•์„ ์ค‘์ ์œผ๋กœ ๊ณ„ํšํ•˜์˜€๋‹ค. ๋ณต๋ถ€ ์ „๋‹จ๋ณ€์œ„๋กœ ์ดˆ๊ธฐ ๊ท ์—ด ๋ฐœ์ƒ ๋ฐ ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์„ ํŒ๋‹จํ•˜๊ธฐ ์œ„ํ•จ์ด๋‹ค. ๋ณ€์œ„๊ณ„์ธก์€ ๊ฐ€๋ ฅ๋ถ€ ์ˆ˜์ง๋ณ€์œ„, ๋ณต๋ถ€ 45ยฐ ์ „๋‹จ๋ณ€์œ„, ๋ณต๋ถ€ ์ค‘์•™๋ถ€ ์ฃผ ๋ณ€์œ„ ๋ฐฉํ–ฅ์˜ ์„ธ ๊ณณ์œผ๋กœ ๊ณ„ํšํ•˜์˜€๋‹ค. ๊ฐ€๋ ฅ๋ถ€ ์ˆ˜์ง๋ณ€ํ˜•์€ ๊ฐ€๋ ฅ๋ถ€ ์ง€์ ์„ ์ค‘์‹ฌ์œผ๋กœ ์ขŒ์šฐ์— ํ•˜๋‚˜์”ฉ ์ด 3์ ์„ ์ธก์ •ํ•˜์˜€๊ณ , ๋ณต๋ถ€ 45ยฐ ์ „๋‹จ๋ณ€์œ„๋Š” ์ธ์žฅ์ธก ๋Œ€๊ฐ๋ฐฉํ–ฅ์œผ๋กœ ๊ฐ€๋ ฅ๋ถ€ ๊ธฐ์ค€์œผ๋กœ ์–‘ ์ชฝ์— 3๊ฐœ์”ฉ ๋Œ€์นญ์ด ๋˜๋„๋ก ์ด 6๊ฐœ LVDT๋ฅผ ์„ค์น˜ํ•˜์˜€๋‹ค.

๋˜ํ•œ ๋ณต๋ถ€ ์ค‘ ๊ฐ€์šด๋ฐ 1๊ณณ์— ์ˆ˜์ง, ์ˆ˜ํ‰, ๋Œ€๊ฐ๋ฐฉํ–ฅ์— ๋ชจ๋‘ LVDT๋ฅผ ์„ค์น˜ํ•˜์—ฌ ์ฃผ๋ณ€ํ˜•(principal strain)๋ฐฉํ–ฅ์„ ๊ณ„์ธกํ•˜์˜€๋‹ค. ์ฃผ๋ณ€ํ˜• ๋ฐฉํ–ฅ์€ ์ „๋‹จ ๊ฐ•๋„ ์ค‘ ๊ฐ•์„ฌ์œ  ๊ธฐ์—ฌ๋ถ„์„ ์‚ฐ์ •ํ•  ๋•Œ ์ •์˜๋˜๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด๊ฐ๋„, ํ˜น์€ ๋ณ€๊ฐํŠธ๋Ÿฌ์Šค๋ชจ๋ธ์—์˜ ์ ์šฉ์‹œ ๋ณต๋ถ€ ํŠธ๋Ÿฌ์Šค ๊ฐ๋„๋กœ ๊ฐ„์ฃผ๋  ์ˆ˜ ์žˆ๋‹ค. ๋ณ€๊ฐํŠธ๋Ÿฌ์Šค๋ชจ๋ธ์€ ์œ ๋กœ์ฝ”๋“œ14)์—์„œ ์‚ฌ์šฉํ•˜๊ณ  ์žˆ๋Š” ๊ฐœ๋…์œผ๋กœ, ๋ถ€์žฌ ๋ณต๋ถ€์—์„œ ์ดˆ๊ธฐ๊ท ์—ด๋ฐœ์ƒ ์ดํ›„ ์ „๋‹จ์ฒ ๊ทผ์— ์˜ํ•œ ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ ๋Šฅ๋ ฅ์— ์˜ํ•ด ๋ณต๋ถ€ ์‘๋ ฅ์žฅ ์˜์—ญ์ด ํ™•๋Œ€๋˜๋ฉฐ, ํŒŒ๊ดด ์‹œ ์ „๋‹จ๋ ฅ์ด ๋ฏธ์น˜๋Š” ์‘๋ ฅ์žฅ์˜ ์ฃผ์‘๋ ฅ ๊ฐ๋„ /Resources/kci/JKCI.2017.29.1.053/images/PIC9FE3.gif๊ฐ€ ์ตœ๋Œ€๊ฐ•๋„๋ฅผ ๊ฒฐ์ •ํ•œ๋‹ค๊ณ  ๋ณธ๋‹ค. UHPFRC๋Š” ์ „๋‹จ์ฒ ๊ทผ์ด ๋ณ„๋„๋กœ ๋ฐฐ๊ทผ๋˜์–ด ์žˆ์ง€ ์•Š๊ณ , ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์™€ ๊ฐ™์ด ์ธ์žฅ์žฌ์™€ ์••์ถ•์žฌ๋ฅผ ๋ณ„๋„๋กœ ๊ตฌ๋ถ„ํ•ด์„œ ํ•ด์„ํ•˜๋Š” ๊ฒƒ์ด ๋ถˆ๊ฐ€๋Šฅํ•˜๋ฏ€๋กœ, ์ƒ๊ธฐ ๋ชจ๋ธ์˜ ๊ฐœ๋…์œผ๋กœ ์ ‘๊ทผํ•˜๋Š” ๊ฒƒ์ด ํ•ฉ๋ฆฌ์ ์ด๋‹ค. Walraven et al. (2013)15)์€ ๋ณต๋ถ€์— ์ˆ˜์ง, ์ˆ˜ํ‰, ๋Œ€๊ฐ LVDT๋ฅผ ์„ค์น˜ํ•˜์—ฌ ์–ป์€ ๊ณ„์ธก๊ฐ’์„ ๋ชจ์–ด ๋ณ€ํ˜•๋ฅ  ์›์„ ์ด์šฉํ•˜์—ฌ ์ฃผ๋ณ€ํ˜•๊ฐ๋„๋ฅผ ๊ณ„์‚ฐํ•œ ํ›„, ์ฃผ๋ณ€ํ˜•๊ฐ๋„์™€ ์ฃผ์‘๋ ฅ๊ฐ๋„๊ฐ€ ๋™์ผํ•˜๋‹ค๋Š” ๊ฐ€์ • ํ•˜์— ๋ณ€๊ฐ ํŠธ๋Ÿฌ์Šค ๋ชจ๋ธ์— ์ ์šฉํ•˜์—ฌ ์œ ํšจ์„ฑ์„ ๊ฒ€์ฆํ•˜์˜€์œผ๋ฉฐ, ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ด๋ฅผ ์ฐธ์กฐํ•˜์˜€๋‹ค. ๋ณต๋ถ€ LVDT๋Š” Fig. 3์— ์ ์„ ์œผ๋กœ ํ‘œ์‹œ๋˜์–ด ์žˆ๋‹ค. ๋ณ€ํ˜•๊ณ„์ธก์€ ํœจ์ฒ ๊ทผ ์ธ์žฅ๋ณ€ํ˜•, ์ค‘๋ฆฝ์ถ•๊ณผ ์ƒ๋ถ€ ํ”Œ๋žœ์ง€ ์ฝ˜ํฌ๋ฆฌํŠธ ์••์ถ•๋ณ€ํ˜•, ๋ณต๋ถ€ ์ค‘์•™๋ถ€ ์ฃผ๋ณ€์œ„ ๋ฐฉํ–ฅ์œผ๋กœ ์Šคํ‹ธ ๊ฒŒ์ด์ง€ ๋ฐ ์ฝ˜ํฌ๋ฆฌํŠธ์— ๊ฒŒ์ด์ง€๋ฅผ ๋ถ€์ฐฉํ•˜์—ฌ ์ธก์ •ํ•˜์˜€๋‹ค. ์••์ถ• ํ”Œ๋žœ์ง€์™€ ์ธ์žฅ ํ”Œ๋žœ์ง€์—๋Š” ๋ณด ๊ฐ€์šด๋ฐ๋ฅผ ๊ธฐ์ค€์œผ๋กœ ์™ผ์ชฝ 4๊ณณ์— ๋™์ผํ•œ ์œ„์น˜๋กœ ๋ถ€์ฐฉํ•˜์˜€๊ณ , ์˜ค๋ฅธ์ชฝ ๋ณต๋ถ€ ์ค‘์•™์— 3์ถ• ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฒŒ์ด์ง€๋ฅผ ๋ถ€์ฐฉํ•˜์—ฌ LVDT์— ์˜ํ•œ ๊ณ„์ธก๊ฐ’๊ณผ ๋น„๊ตํ•˜์—ฌ ์ฃผ ๋ณ€ํ˜• ๋ฐฉํ–ฅ์„ ๊ณ„์ธก๊ฐ’์„ ๊ฒ€์ฆํ•˜๊ณ ์ž ํ•˜์˜€๋‹ค.

2.3 ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„ ์‹คํ—˜ ๊ณ„ํš ๋ฐ ๊ฒฐ๊ณผ

UHPFRC์˜ ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„๋Š” ์ „๋‹จ์„ค๊ณ„์˜ ์ฃผ์š”ํ•œ ๋ณ€์ˆ˜๊ฐ€ ๋œ๋‹ค. ํฐ ๊ณจ์žฌ๋ฅผ ๊ฐ€์ง„ ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ๊ท ์—ด๋ฐœ์ƒ ํ›„ ๊ฑฐ์˜ ์ฆ‰์‹œ ์ตœ๋Œ€ ์ธ์žฅ๊ฐ•๋„๊ฐ€ ๋ฐœํ˜„๋˜๋Š” ๋ฐ˜๋ฉด, ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ๊ท ์—ด ํ›„ ๋น„์„ ํ˜• ๊ตฌ๊ฐ„ ๋ฐ ์ตœ๋Œ€๊ฐ•๋„ ๋„๋‹ฌ ํ›„์˜ ์—ฐํ™”๊ฑฐ๋™์ด ๋งค์šฐ ํฌ๋‹ค. ๊ท ์—ด ํ›„ ๊ฑฐ๋™ ํŠน์„ฑ์€ ๋ถ€์žฌ๊ฑฐ๋™์— ํฌ๊ฒŒ ์˜ํ–ฅ์„ ๋ผ์น˜๊ธฐ ๋•Œ๋ฌธ์— ์ธ์žฅ์‘๋ ฅ-๋ณ€ํ˜• ๊ด€๊ณ„๊ฐ€ ์ค‘์š”ํ•˜๋‹ค. Fig. 1๊ณผ ๊ฐ™์ด ๋ถ€์žฌ๊ฐ€ ์‚ฌ์ธ์žฅ ๊ท ์—ด์— ์˜ํ•ด ํŒŒ๊ดด๋  ๊ฒฝ์šฐ, ์ตœ๋Œ€ ๊ฐ•๋„์— ๋„๋‹ฌํ•  ๋•Œ ์‚ฌ์ธ์žฅ์„ ๋”ฐ๋ผ ๋ฐœ์ƒํ•˜๋Š” ์ธ์žฅ๊ฐ•๋„-๊ท ์—ดํญ ๊ด€๊ณ„์—์„œ ๊ท ์—ด ๋ฐœ์ƒ ์‹œ์ž‘์ ์—์„œ๋ถ€ํ„ฐ ํ•œ๊ณ„ ๊ท ์—ดํญ(/Resources/kci/JKCI.2017.29.1.053/images/PICA013.gif)์— ์ด๋ฅด๊ธฐ๊นŒ์ง€ ๋ถ€๋ถ„์˜ ํ‰๊ท  ์ธ์žฅ๊ฐ•๋„๊ฐ€ ๊ท ์—ด๋ฉด์— ์ˆ˜์ง์œผ๋กœ ์ €ํ•ญํ•œ๋‹ค๊ณ  ๋ณด๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.12) ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” Fig. 2๋ฅผ ์ฐธ๊ณ ํ•˜์—ฌ ์ง์ ‘์ธ์žฅ ์‹คํ—˜๊ณผ ํœจ์ธ์žฅ ์‹คํ—˜์„ ๋™์‹œ์— ์ˆ˜ํ–‰ํ•˜๋˜, ๊ท ์—ดํญ์— ๋”ฐ๋ฅธ ์ž”๋ฅ˜์ธ์žฅ์‘๋ ฅ์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•˜์—ฌ ๋…ธ์น˜๊ฐ€ ์žˆ๋Š” ์‹œํŽธ์„ ์ ์šฉํ•˜์˜€๋‹ค. ์œ ๋กœ์ฝ”๋“œ16) ๋ฐ JCI17)์—์„œ๋Š” SFRC์˜ ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„๋Š” ๋…ธ์น˜๊ฐ€ ์žˆ๋Š” ์ง์œก๋ฉด์ฒด ๋ณด์˜ 3์  ์žฌํ•˜ ์‹คํ—˜์„ ํ†ตํ•ด ๊ตฌํ•˜๋„๋ก ๊ทœ์ •ํ•˜๊ณ  ์žˆ๋‹ค. ๋…ธ์น˜๊ฐ€ ์žˆ๋Š” ์‹œํŽธ์€ ๋…ธ์น˜ํญ์„ ๊ท ์—ด ๊ฐœ๊ตฌ ๋ณ€์œ„(CMOD)๋กœ ์ •์˜ํ•˜๊ณ  ํ•˜์ค‘๊ณผ CMOD ๊ด€๊ณ„๋ฅผ ํ†ตํ•ด ๊ท ์—ด ํ›„ ์ž”๋ฅ˜์‘๋ ฅ์„ ํ†ตํ•ด ์ธ์žฅ๊ฐ•๋„ ๋ฐ ๊ท ์—ด ํ›„ ๊ฑฐ๋™์œผ๋กœ ๋ถ„์„๋œ๋‹ค. ์ผ๋ฐ˜์ ์œผ๋กœ๋Š” ์œ ํ•œ์š”์†Œํ•ด์„์— ์˜ํ•œ ์—ญํ•ด์„์„ ํ†ตํ•ด ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„-CMOD ๋น„์„ ํ˜• ํ•จ์ˆ˜๋ฅผ ๋„์ถœํ•˜๋Š” ๋ฐฉ๋ฒ•18)์ด ๋งŽ์ด ์‚ฌ์šฉ๋˜๊ณ  ์žˆ์œผ๋‚˜, ์ ์šฉ ๋‚œ์ด๋„๊ฐ€ ๋†’๊ณ  ํ•ด์˜ ์ˆ˜๋ ด์„ฑ์ด ๋–จ์–ด์ง€๋Š” ์–ด๋ ค์›€์ด ์žˆ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์œ ๋Ÿฝ์ฝ˜ํฌ๋ฆฌํŠธํ•™ํšŒ ๋ชจ๋ธ์ฝ”๋“œ(fib model code 2010)19)์—์„œ ์ œ์•ˆํ•˜๋Š” ํ•˜์ค‘-๋ณ€์œ„๊ด€๊ณ„์‹์„ ํ†ตํ•ด ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„๋ฅผ ๊ตฌํ•˜์˜€๋‹ค. fib ๋ชจ๋ธ์€ ์ธ์žฅ๊ฒฝํ™” ํ˜น์€ ์—ฐํ™”๊ฑฐ๋™์„ ๋ณด์ด๋Š” FRC ์žฌ๋ฃŒ์— ๋Œ€ํ•ด ํ•˜์ค‘-๋ณ€์œ„๊ด€๊ณ„๋ฅผ ํ•œ๊ณ„ ๊ท ์—ดํญ์— ๋Œ€ํ•ด ์„ ํ˜•์œผ๋กœ ๊ฐ€์ •ํ•˜๊ณ , ์‹ (2)์™€ ๊ฐ™์ด ์‚ฌ์šฉ ์ธ์žฅํ•˜์ค‘(/Resources/kci/JKCI.2017.29.1.053/images/PICA043.gif)๊ณผ ํ•œ๊ณ„ ์ธ์žฅํ•˜์ค‘(/Resources/kci/JKCI.2017.29.1.053/images/PICA073.gif)์„ ๊ตฌํ•œ๋‹ค. ์ด๋•Œ /Resources/kci/JKCI.2017.29.1.053/images/PICA093.gif๋Š” ์‹คํ—˜๊ฒฐ๊ณผ ํŠน์ • CMOD์— ์ €ํ•ญํ•˜๋Š” ์ž”๋ฅ˜ ํœจ์ธ์žฅ๊ฐ•๋„์ด๋ฉฐ ์ด ๊ฐ’์€ EN 1465116)์— ์ œ์‹œ๋˜์–ด ์žˆ๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/PICA0B3.gif (2-1)

/Resources/kci/JKCI.2017.29.1.053/images/PICA131.gif (2-2)

ํ•œํŽธ, ์—ญํ•ด์„ ์—†์ด ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„๋ฅผ ๋ฐ”๋กœ ์–ป๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ง์ ‘ ์ธ์žฅ ์‹œํ—˜์ด ํ•„์š”ํ•œ๋ฐ ์ง์ ‘ ์ธ์žฅ ์‹œํ—˜๋ฒ•์€ ๊ทธ ๋ฐฉ๋ฒ•์ด ๋‹ค์–‘ํ•˜๊ณ  ์‹œํŽธํฌ๊ธฐ ๋ฐ ๊ตฌ์†์กฐ๊ฑด์— ๋Œ€ํ•œ ๊ฒฐ๊ณผ๊ฐ’์— ์ฐจ์ด๊ฐ€ ํฌ๋‹ค.20) ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ K-UHPC ๊ตฌ์กฐ์„ค๊ณ„์ง€์นจ21)์— ์˜๊ฑฐ, ๋…ธ์น˜๊ฐ€ ์žˆ๋Š” ์‹œํŽธ์— ์–‘ ๋‹จ๋ถ€๋Š” ํžŒ์ง€๋กœ ์ ์šฉํ•˜์˜€๋‹ค. ๊ทธ ๊ฒฐ๊ณผ๋Š” Fig. 4(b)์™€ ๊ฐ™๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F4.jpg

Fig. 4 Tensile response of UHPFRC; (a) Load-CMOD curves and test set-up of three-point loading on notched prism required by EN 14651, (b) stress-CMOD curves and test set-up of direct tension test on doubly notched plate

Fig. 4(a)๋Š” EN 14651์— ์˜๊ฑฐํ•œ ํœจ์ธ์žฅ ์‹œํ—˜๋ฒ• ๊ฒฐ๊ณผ ์–ป์€ ํ•˜์ค‘-CMOD ๊ทธ๋ž˜ํ”„์ด๋‹ค. ์ด ๊ฐ’์„ ์‹ (2)๋ฅผ ํ†ตํ•ด /Resources/kci/JKCI.2017.29.1.053/images/PICA180.gif๋ฅผ 0.03mm๋กœ ๊ฐ€์ •ํ•˜์—ฌ Table 2์™€ ๊ฐ™์€ ๊ฒฐ๊ณผ๋ฅผ ์–ป์—ˆ๋‹ค. ์ง์ ‘์ธ์žฅ ์‹คํ—˜๊ฒฐ๊ณผ๋Š” ์žฌ๋ฃŒ๋ณ„, ์‹œํŽธ๋ณ„ ํŽธ์ฐจ๊ฐ€ ํฐ ๋ฐ ๋ฐ˜ํ•ด ํœจ์ธ์žฅ ์‹คํ—˜๊ฒฐ๊ณผ๋Š” ์•ˆ์ •์ ์ด๋‹ค. ์ง์ ‘์ธ์žฅ ์‹คํ—˜๊ฒฐ๊ณผ ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„ 1.5%์ธ ๋ฐฐํ•ฉ 1๊ณผ 2์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์œ ์‚ฌํ•˜๊ณ  ๋šœ๋ ทํ•œ ์ธ์žฅ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์˜€์œผ๋ฉฐ, ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„ 1.0%์ธ ๋ฐฐํ•ฉ 3์€ ์ธ์žฅ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด์ง€ ์•Š์œผ๋‚˜ ํœจ์ธ์žฅ์‹คํ—˜์—์„œ๋Š” ํ•˜์ค‘-์ฒ˜์ง๊ด€๊ณ„์—์„œ ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์••์ถ•๊ฑฐ๋™์€ ์ตœ๋Œ€ํ•˜์ค‘์— ์ด๋ฅด๊ธฐ๊นŒ์ง€ ์„ ํ˜•์ ์œผ๋กœ ์ฆ๊ฐ€ํ•˜๋ฉฐ ๊ฐ•๋„๋Š” ์„ธ ๊ฐ€์ง€ ๋ฐฐํ•ฉ ๋ชจ๋‘ 160~170MPa๋กœ ์œ ์‚ฌํ•˜๋‹ค.

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Table 1 Mix proportion (in mass ratio)

* B (premix Binder): cement, Zr, BS, filler, expansion agent, shrinkage reducing agent premix

* A (fine Aggregates), SF (Steel Fiber), S (Superplasticizer), G (air-entraining aGent)

AFGC์—์„œ๋Š” ์ธ์žฅ๊ฐ•๋„-CMOD ๊ทธ๋ž˜ํ”„/Resources/kci/JKCI.2017.29.1.053/images/PICA1C0.gif์—์„œ ์ „๋‹จ๊ฐ•๋„์— ์‚ฌ์šฉํ•˜๋Š” ์ž”๋ฅ˜๊ฐ•๋„/Resources/kci/JKCI.2017.29.1.053/images/PICA1FF.gif๋ฅผ ํ•œ๊ณ„ ๊ท ์—ดํญ/Resources/kci/JKCI.2017.29.1.053/images/PICA220.gif์— ์ด๋ฅด๊ธฐ๊นŒ์ง€์˜ ๋ฒ”์œ„์˜ ํ‰๊ท ๊ฐ’์— ๊ฐ•์„ฌ์œ  ์˜ํ–ฅ์— ๋”ฐ๋ฅธ ๊ณ„์ˆ˜/Resources/kci/JKCI.2017.29.1.053/images/PICA27E.gif๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ์‹ (3)๊ณผ ๊ฐ™์ด ์ •์˜ํ•˜๊ณ  ์žˆ๋‹ค. /Resources/kci/JKCI.2017.29.1.053/images/PICA2BE.gif๋Š” ์ผ๋ฐ˜ ๊ตฌ์กฐ๋ฌผ์˜ ๊ฒฝ์šฐ 1.25๋ฅผ ์‚ฌ์šฉํ•œ๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/PICA34C.gif (3)

Table 2์— ์ œ์‹œ๋œ /Resources/kci/JKCI.2017.29.1.053/images/PICA3CA.gif์™€ /Resources/kci/JKCI.2017.29.1.053/images/PICA3F9.gif๋Š” ์„ค๊ณ„ ์ธ์žฅ๊ฐ•๋„๋กœ์จ, ์ง์ ‘์‹คํ—˜์— ์˜ํ•œ ์„ค๊ณ„ ์ž”๋ฅ˜ ์ธ์žฅ ๊ฐ•๋„/Resources/kci/JKCI.2017.29.1.053/images/PICA41A.gif์™€ ๋น„๊ตํ•  ์ˆ˜ ์žˆ๋‹ค. ์„ค๊ณ„์ธ์žฅ๊ฐ•๋„๋Š” ์ž”๋ฅ˜์ธ์žฅ๊ฐ•๋„/Resources/kci/JKCI.2017.29.1.053/images/PICA43A.gif์™€ ํœจ์ธ์žฅ ์‹คํ—˜๊ฒฐ๊ณผ์—์„œ ์–ป์€ /Resources/kci/JKCI.2017.29.1.053/images/PICA45A.gif ์ค‘ ์–ด๋Š ๊ฒƒ์„ ์‚ฌ์šฉํ•˜์—ฌ๋„ ๋ฌด๋ฐฉํ•˜๋‚˜, ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” /Resources/kci/JKCI.2017.29.1.053/images/PICA49A.gif๋ฅผ ์ ์šฉํ•˜์˜€์œผ๋ฉฐ ๊ทธ ๊ทผ๊ฑฐ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค. /Resources/kci/JKCI.2017.29.1.053/images/PICA4D9.gif์™€ /Resources/kci/JKCI.2017.29.1.053/images/PICA509.gif์˜ ๊ณฑ, ์ฆ‰ ํ•˜์ค‘-๋ณ€์œ„ ์„ ํ˜•๊ด€๊ณ„์—์„œ์˜ ๋ฉด์ ์ธ ํŒŒ๊ดด์—๋„ˆ์ง€/Resources/kci/JKCI.2017.29.1.053/images/PICA539.gif๋Š” ํœจ์ธ์žฅ ์‹œํ—˜์— ์˜ํ•œ ํŒŒ๊ดด์—๋„ˆ์ง€ ๊ฐ’๊ณผ ์œ ์‚ฌํ•˜๋‹ค. ์ด๋Š” ์‹œํŽธ๋ณ„ ๊ฐ•๋„์˜ ์ฐจ์ด๊ฐ€ ํ•œ๊ณ„ ๊ท ์—ดํญ /Resources/kci/JKCI.2017.29.1.053/images/PICA598.gif ์ฐจ์ด์™€ ์ง์ ‘์ ์ธ ๊ด€๋ จ์ด ์žˆ์Œ์„ ์˜๋ฏธํ•œ๋‹ค. /Resources/kci/JKCI.2017.29.1.053/images/PICA5B8.gif๋Š” /Resources/kci/JKCI.2017.29.1.053/images/PICA5E8.gif๋ฅผ 0.3mm๋กœ ๊ฐ€์ •ํ–ˆ์„ ๋•Œ์˜ ์„ค๊ณ„ ์ธ์žฅ๊ฐ•๋„์ด๋‚˜, /Resources/kci/JKCI.2017.29.1.053/images/PICA608.gif๋Š” ์‹คํ—˜๊ฒฐ๊ณผ์— ๋”ฐ๋ฅธ /Resources/kci/JKCI.2017.29.1.053/images/PICA638.gif์—์„œ์˜ ํ‰๊ท ๊ฐ’์œผ๋กœ ์ •์˜ํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. Fig. 1์—์„œ์™€ ๊ฐ™์ด ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์—์„œ ์ฃผ์š” ์™ธ๋ ฅ์ €ํ•ญ ๊ธฐ์ œ๋Š” ๊ฐ•์„ฌ์œ ์— ์˜ํ•œ ์‘๋ ฅ ์žฌ๋ถ„๋ฐฐํšจ๊ณผ๋กœ, ์ด๋Š” ์ตœ๋Œ€ ๊ฐ•๋„๊ฐ€ ์•„๋‹Œ ํ•œ๊ณ„ ๊ท ์—ดํญ์œผ๋กœ ์ •์˜๋œ๋‹ค. ๋ถ€์žฌ ๊ฑฐ๋™์—์„œ ํ•œ๊ณ„ ๊ท ์—ดํญ์€ ํœจ์ฒ ๊ทผ๋น„, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„ ๋“ฑ ์—ฌ๋Ÿฌ ์„ค๊ณ„๋ณ€์ˆ˜์— ์˜ํ–ฅ์„ ๋ฐ›๊ธฐ ๋•Œ๋ฌธ์— ๋ณด์ˆ˜์ ์œผ๋กœ ๊ณ ๋ คํ•˜์—ฌ, ํ•œ๊ณ„ ๊ท ์—ดํญ์„ 0.3mm์ผ ๋•Œ๋ฅผ ๊ธฐ์ค€์œผ๋กœ ์„ค๊ณ„์ธ์žฅ๊ฐ•๋„๋ฅผ ์ •์˜ํ•˜๋Š” ๊ฒƒ์ด ๋ฐ”๋žŒ์งํ•˜๋‹ค. ๋˜ํ•œ ๋ฐฐํ•ฉ 3์˜ ๊ฒฝ์šฐ /Resources/kci/JKCI.2017.29.1.053/images/PICA658.gif์™€ /Resources/kci/JKCI.2017.29.1.053/images/PICA698.gif๊ฐ’์˜ ์ฐจ์ด๊ฐ€ ํฐ๋ฐ, ์žฌ๋ฃŒ์ธ์žฅ์‘๋ ฅ-๋ณ€ํ˜•๊ด€๊ณ„๋Š” ์—ฐํ™”๊ฑฐ๋™์„, ํœจ๊ฐ•๋„-์ฒ˜์ง๊ด€๊ณ„๋Š” ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํ•ด์„ํ•  ์ˆ˜ ์žˆ๋‹ค (Fig. 2). ์ด๋Ÿฌํ•œ ์žฌ๋ฃŒ์˜ ๊ฒฝ์šฐ ๋ถ€์žฌ ์„ค๊ณ„ ์‹œ ์ฃผ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ํ›„์—๋„ ์ด๋ฅผ ๊ตฌ์†ํ•˜๊ณ  ์žˆ๋Š” ํž˜์ด ์ถฉ๋ถ„ํ•  ๊ฒฝ์šฐ๋Š” ๊ท ์—ด๋ฐœ์ƒ ํ›„ ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด๋ฏ€๋กœ, ๋ณธ ์—ฐ๊ตฌ์—์„œ์™€ ๊ฐ™์ด ์••์ถ•๋Œ€ ๋ฐ ํœจ์ธ์žฅ ์ฒ ๊ทผ์ด ์ถฉ๋ถ„ํžˆ ํฌ๊ฒŒ ์„ค๊ณ„๋œ ๊ฒฝ์šฐ /Resources/kci/JKCI.2017.29.1.053/images/PICA6D7.gif๊ฐ’์ด /Resources/kci/JKCI.2017.29.1.053/images/PICA6F7.gif๋ณด๋‹ค ์„ค๊ณ„ ์ธ์žฅ๊ฐ•๋„์— ๋ถ€ํ•ฉํ•œ๋‹ค.

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Table 2 Compressive and tensile characteristics of UHPFRC

*/Resources/kci/JKCI.2017.29.1.053/images/PICA093.gif: residual flexural tensile strength corresponding to (=0.5mm, =2.5mm)

**/Resources/kci/JKCI.2017.29.1.053/images/PICA073.gif: serviceability residual strength, : ultimate residual strength,

3. ์‹คํ—˜ ๊ฒฐ๊ณผ ๋ฐ ๋ถ„์„

3.1 ์‹คํ—˜๋ณ€์ˆ˜์— ๋”ฐ๋ฅธ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„

3.1.1 ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„(a/d)์— ๋”ฐ๋ฅธ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„

์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์—์„œ ์ตœ์†Œ ์ „๋‹จ ๋ณด๊ฐ•๊ทผ์˜ ์—ญํ• ์€ ์‚ฌ์ธ์žฅ ๊ท ์—ด ๋ฐœ์ƒ ์ดํ›„์˜ ์—ฌ์œ  ๋‚ด๋ ฅ๊ณผ ์‚ฌ์ธ์žฅ ๊ท ์—ด ํญ์˜ ์–ต์ œ์˜ ๊ด€์ ์—์„œ ํ•ด์„๋  ์ˆ˜ ์žˆ๋‹ค.22) ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•์ด ์ตœ์†Œ ์ „๋‹จ ๋ณด๊ฐ•๊ทผ์˜ ์—ญํ• ์„ ๋Œ€์ฒดํ•  ์ˆ˜ ์žˆ๋Š”๊ฐ€๋ฅผ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•˜์—ฌ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ๋ฐœ์ƒํ–ˆ์„ ๋•Œ์˜ ์ดˆ๊ธฐ ๊ท ์—ด ์ƒํƒœ(initial cracking state)์™€ ์ „๋‹จ ๋‚ด๋ ฅ์ด ์ตœ๋Œ€์ผ ๋•Œ์˜ ๊ทนํ•œ ํ•œ๊ณ„ ์ƒํƒœ(ultimate limit state)๋ฅผ ๊ฐ๊ฐ ์ •์˜ํ•˜์—ฌ, Table 3๊ณผ ๊ฐ™์ด ๊ฐ•๋„ ๋ฐ ๋ณ€ํ˜•์„ ๋น„๊ตํ•˜์˜€๋‹ค. ์ดˆ๊ธฐ ๊ท ์—ด ์ƒํƒœ๋Š” ๋ณต๋ถ€ ๋ณ€์œ„ ๋ฐ ๋ณ€ํ˜•๋ฅ  ๊ณ„์ธก๊ฒฐ๊ณผ๋ฅผ ๊ทผ๊ฑฐ๋กœ ๋ณต๋ถ€์— ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์‹œ์ ์œผ๋กœ ์ •์˜ํ•˜์˜€์œผ๋ฉฐ, ๊ทนํ•œ ํ•œ๊ณ„ ์ƒํƒœ๋Š” ์ „๋‹จ๊ฐ•๋„๊ฐ€ ์ตœ๋Œ€์ผ ๋•Œ๋ฅผ ๊ธฐ์ค€ํ•˜์˜€๋‹ค. ์ดˆ๊ธฐ ๊ท ์—ด ๊ฐ•๋„ ๋Œ€๋น„ ์ตœ๋Œ€ ๊ฐ•๋„์˜ ๋น„๋Š” ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ๋Š” 3๋ฐฐ ์ •๋„์˜€์œผ๋ฉฐ, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ธ ๊ฒฝ์šฐ๋Š” 1.7~2.8๋ฐฐ๋กœ ์ƒ๋Œ€์ ์œผ๋กœ ์ž‘์€ ๊ฐ’์„ ๋ณด์˜€๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๋ชจ๋“  ์‹คํ—˜์ฒด์—์„œ ์ดˆ๊ธฐ ๊ท ์—ด ๋ฐœ์ƒ ์ดํ›„ ๊ฐ•์„ฑ์˜ ๋ณ€ํ™”๋ฅผ ์ˆ˜๋ฐ˜ํ•œ ์•ˆ์ •์ ์ธ ํ•˜์ค‘ ์ฆ๊ฐ€๋ฅผ ๋ณด์˜€์œผ๋ฉฐ, ๊ฐ•์„ฑ ์ €ํ•˜ ์ •๋„๊ฐ€ ํฌ์ง€ ์•Š์•˜๋‹ค. ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์—์„œ ์ „๋‹จ ์ฒ ๊ทผ์ด ์ถฉ๋ถ„ํžˆ ๋ฐฐ๊ทผ๋œ ๊ฒฝ์šฐ์™€ ๋น„์Šทํ•œ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„๋ฅผ ๋ณด์˜€๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/Table_CONCRETE_29_01_06_T3.jpg

Table 3 Test results of UHPFRC I-shaped shear beam

* DT (Diagonal tension failure), FS (Flexural shear failure)

ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„๋Š” ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ์™€ 3.5์ธ ๊ฒฝ์šฐ์—๋Š” ๋šœ๋ ทํ•œ ์ฐจ์ด๋ฅผ ๋ณด์˜€๋‹ค. ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ๋Š” ๊ฐ•์„ฑ, ์ตœ๋Œ€ ๊ฐ•๋„๊ฐ€ ๋ชจ๋‘ ํฌ๊ณ  ์ทจ์„ฑ์ ์œผ๋กœ ํŒŒ๊ดด๋œ ๋ฐ˜๋ฉด, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ธ ๊ฒฝ์šฐ๋Š” ๊ฐ•์„ฑ, ์ตœ๋Œ€ ๊ฐ•๋„๊ฐ€ ์ค„์–ด๋“ค๋ฉด์„œ ์ตœ๋Œ€ ๊ฐ•๋„ ์ดํ›„ ์ƒ๋ถ€ ํ”Œ๋žœ์ง€ ์••์ถ•๋Œ€๊ฐ€ ๋ณ€ํ˜•์— ์ €ํ•ญํ•˜๋ฉด์„œ ์ƒ๋Œ€์ ์œผ๋กœ ์—ฐ์„ฑ์ ์ธ ํŒŒ๊ดด๋ฅผ ๋ณด์˜€๋‹ค. ์ดˆ๊ธฐ๊ท ์—ด์€ ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ๋Š” ๋ชจ๋‘ ๋ณต๋ถ€์— 45ยฐ ์‚ฌ์ธ์žฅ ๊ท ์—ด๋กœ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ธ ๊ฒฝ์šฐ๋Š” ๋ณต๋ถ€ ์‚ฌ์ธ์žฅ ๊ท ์—ด๊ณผ ๋ณด ํ•˜๋‹จ ํœจ๊ท ์—ด์ด ๋™์‹œ์— ๊ด€์ฐฐ๋˜๋ฉด์„œ ๊ฐ•์„ฑ๊ณผ ๊ฐ•๋„ ๊ฐ์†Œ๋ฅผ ๋ณด์˜€๋‹ค(Fig. 5). ๊ทนํ•œ ํ•œ๊ณ„ ์ƒํƒœ์—์„œ ์ตœ๋Œ€ ๊ฐ•๋„๋Š” 9๊ฐœ ์‹คํ—˜์ฒด ๋ชจ๋‘ ๋ณต๋ถ€ ์‚ฌ์ธ์žฅ ๊ท ์—ด ์ค‘ 1~2๊ฐœ ๊ท ์—ดํญ์ด ๋ˆˆ์— ๋„๊ฒŒ ํฌ๊ฒŒ ๋ฒŒ์–ด์ง€๋ฉด์„œ ๊ท ์—ดํญ์ด ์•ฝ 0.5mm์— ๋„๋‹ฌํ•  ๋•Œ ๋ฐœํ˜„๋˜์—ˆ๋‹ค. ์ตœ๋Œ€๊ฐ•๋„๋ฅผ ๊ฒฐ์ •ํ•˜๋Š” ํŒŒ๊ดด๋ชจ๋“œ๋Š” ์‹คํ—˜์ฒด 2-S35-B๋ฅผ ์ œ์™ธํ•˜๊ณ  ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์— ์˜ํ•œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋กœ ๊ด€์ฐฐ๋˜์—ˆ๋‹ค. ์‹คํ—˜์ฒด 2-S25-B๋Š” ์ง€์ ๋ถ€ ๊ทผ์ฒ˜ ๋ณต๋ถ€๊นŒ์ง€ ํ›จ์”ฌ ๋„“์€ ๊ตฌ๊ฒฉ์— ์ž”๊ท ์—ด์ด ์ง„์ „๋˜์–ด ์ง€์ ๋ถ€ ์ƒ๋‹จ ๋ณต๋ถ€์˜ ํŒŒ๋‹จ์— ์˜ํ•ด ์ตœ๋Œ€ ๊ฐ•๋„๊ฐ€ ๊ฒฐ์ •๋˜์—ˆ์œผ๋ฉฐ (Fig. 6), ๋‹ค๋ฅธ ์‹คํ—˜์ฒด์— ๋น„ํ•ด ํฐ ์ตœ๋Œ€ ๊ฐ•๋„๋ฅผ ๊ธฐ๋กํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F5.jpg

Fig. 5 Shear force versus vertical displacement for specimens with respect to (a) shear span ratio and (b) effective depth

/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F6.jpg

Fig. 6 Crack pattern and location of critical shear crack in web

3.1.2 ์œ ํšจ๋†’์ด(d)์— ๋”ฐ๋ฅธ ํ•˜์ค‘-๋ณ€์œ„ ๊ด€๊ณ„

์œ ํšจ๋†’์ด๊ฐ€ ํด์ˆ˜๋ก ์ตœ๋Œ€ ๊ฐ•๋„๊ฐ€ ํด ๊ฒƒ์œผ๋กœ ์˜ˆ์ƒํ•˜์˜€์œผ๋‚˜ Fig. 5(b)์™€ ๊ฐ™์ด ํŒŒ๊ดด๋ชจ๋“œ๊ฐ€ ๋‹ค๋ฅธ 2-S35-B๋ฅผ ์ œ์™ธํ•˜๊ณ  ๊ฐ•์„ฑ, ์ตœ๋Œ€ ๊ฐ•๋„ ๋ชจ๋‘ ํฐ ์ฐจ์ด๊ฐ€ ์—†์—ˆ์œผ๋ฉฐ, ์œ ํšจ๋†’์ด๊ฐ€ ํฐ ๊ฒฝ์šฐ๋Š” ์ตœ๋Œ€๊ฐ•๋„ ๋„๋‹ฌ ์ดํ›„ ํ•˜์ค‘์ด ๊ธ‰๊ฒฉํ•˜๊ฒŒ ๋–จ์–ด์ง€๋ฉฐ ์ทจ์„ฑ์ ์ธ ๊ฑฐ๋™์„ ๋ณด์˜€๋‹ค. ์ดˆ๊ธฐ ๊ท ์—ด ๊ฐ•๋„ ๋Œ€๋น„ ์ตœ๋Œ€ ๊ฐ•๋„๋น„ ์—ญ์‹œ 2-S35-B๋ฅผ ์ œ์™ธํ•˜๊ณ  ์œ ํšจ๋†’์ด ์ฆ๊ฐ€์— ๋”ฐ๋ผ ๊ทธ ๊ฐ’์ด ๊ฐ์†Œํ•˜์˜€๋‹ค. ์ดˆ๊ธฐ ๊ท ์—ด ๊ฐ•๋„๋Š” ์œ ํšจ๋†’์ด๊ฐ€ 445mm์ธ ๊ฒฝ์šฐ์— ๋น„ํ•ด 625mm์ธ ๊ฒฝ์šฐ๊ฐ€ ํฌ์ง€๋งŒ, ์ตœ๋Œ€ ๊ฐ•๋„๋Š” ๊ฑฐ์˜ ์ฆ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

์ด๋Ÿฌํ•œ ๊ฒฐ๊ณผ๋Š” ๋ณต๋ถ€ ๊ท ์—ด ์–‘์ƒ ๋ฐ ํŒŒ๊ดด ๋ชจ๋“œ์™€ ๊ด€๊ณ„์ง€์–ด ์ƒ๊ฐํ•ด ๋ณผ ์ˆ˜ ์žˆ๋‹ค. ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ๋ฐฐ๊ทผ๋˜์–ด ์žˆ์ง€ ์•Š์€ ๊ฒฝ์šฐ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋ฅผ ์ˆ˜๋ฐ˜ํ•˜๋ฉฐ ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„ ๋ฟ ์•„๋‹ˆ๋ผ ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„, ์œ ํšจ๋†’์ด, ํœจ์ฒ ๊ทผ๋น„ ๋“ฑ์— ๊ทธ ๊ฑฐ๋™์ด ํฌ๊ฒŒ ์˜ํ–ฅ์„ ๋ฐ›๋Š” ๊ฒƒ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค. ๋ฐ˜๋ฉด ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ๋ฐฐ๊ทผ๋œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฒฝ์šฐ, ์ „๋‹จ๋ณด๊ฐ•๊ทผ์˜ ํ•ญ๋ณต์œผ๋กœ ์ตœ์ข… ํŒŒ๊ดด๋ฅผ ์ •์˜ํ•  ์ˆ˜ ์žˆ๊ณ  ๋ณต๋ถ€ ์‚ฌ์ธ์žฅ ๊ท ์—ด์€ ํ•œ ๊ณณ์— ์ง‘์ค‘๋˜์ง€ ์•Š๊ณ  ํœจ๊ท ์—ด๊ณผ ์ด์–ด์ง€๋ฉฐ ๋„“์€ ๋ฒ”์œ„์— ๊ฑธ์ณ ๊ณ ๋ฅด๊ฒŒ ๋ถ„ํฌ๋˜๋Š” ํŠน์ง•์„ ๊ฐ€์ง„๋‹ค. ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ๋ฐฐ๊ทผ๋˜์ง€ ์•Š์€ UHPFRC ์ „๋‹จ ๋ถ€์žฌ์˜ ๊ท ์—ด ์–‘์ƒ ๋ฐ ํŒŒ๊ดด ๋ชจ๋“œ๋Š” ์ƒ๊ธฐ ๋‘ ๊ฐ€์ง€ ๊ฒฝ์šฐ์˜ ํŠน์ง•์„ ๋ชจ๋‘ ๊ฐ€์ง€๊ณ  ์žˆ๋Š”๋ฐ, ๊ท ์—ด ํ›„ ์ตœ๋Œ€ ํ•˜์ค‘์— ์ด๋ฅด๊ธฐ ๊นŒ์ง€๋Š” ๋ฏธ์„ธ๊ท ์—ด์ด ๋„“์€ ๋ฒ”์œ„์— ๋ถ„ํฌ๋˜๋ฉด์„œ ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ์— ์˜ํ•ด ์„ ํ˜•์ ์œผ๋กœ ํ•˜์ค‘์ฆ๊ฐ€๊ฐ€ ์ด๋ฃจ์–ด์ง€์ง€๋งŒ ์ตœ์ข… ํŒŒ๊ดด๊ฐ€ ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘์— ์˜ํ•œ ์‚ฌ์ธ์žฅ ํŒŒ๊ดด๋กœ ์ •์˜๋œ๋‹ค. ์ฆ‰ ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์—์„œ ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” ๊ฒฝ์šฐ์™€ ๊ฐ™์ด ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„, ํœจ์ฒ ๊ทผ๋น„ ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ํฌ๊ธฐํšจ๊ณผ์˜ ์˜ํ–ฅ์„ ๋ฐ›๋Š”๋‹ค๊ณ  ๋ณผ ์ˆ˜ ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ UHPFRC ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฑฐ๋™์€ ์ดˆ๊ธฐ ๊ท ์—ด ํ›„ ๋ฏธ์„ธ๊ท ์—ด ๋ถ„ํฌ ๋ฐ ์–‘์ƒ, ๊ทธ๋ฆฌ๊ณ  ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘์— ์ด๋ฅด๋Š” ํŒŒ๊ดด ๋ชจ๋“œ์— ๋Œ€ํ•œ ๋ถ„์„์ด ํ•„์š”ํ•˜๋‹ค.

3.2 ๊ท ์—ด ์–‘์ƒ ๋ฐ ํŒŒ๊ดด ๋ชจ๋“œ

UHPFRC์˜ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ๋Š” ์•ž ์ ˆ์—์„œ ์–ธ๊ธ‰ํ•œ ๋ฐ”์™€ ๊ฐ™์ด ๊ท ์—ด ๋ฐœ์ƒ ํ›„ ์ž”์—ฌ๊ฐ•๋„ ๋ฐ ๊ฑฐ๋™์œผ๋กœ ์„ค๋ช…ํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ท ์—ด์€ ๋งคํŠธ๋ฆญ์Šค์— ๋ถ„ํฌ๋œ ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ๊ทธ ํญ์ด ์ œํ•œ๋˜๋ฉฐ ๋ฏธ์„ธํ•œ ๊ท ์—ด์ด ๋„“์€ ๋ฉด์ ์— ๊ฑธ์ณ ํฌ๊ฒŒ ๋ถ„ํฌ๋˜๋ฉด์„œ ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•œ๋‹ค. ๊ท ์—ด ์–‘์ƒ์€ ์ฃผ๊ท ์—ด์˜ ์œ„์น˜ ๋ฐ ๊ฐ๋„, ๊ท ์—ด ๋ถ„ํฌ์˜ ๋ฒ”์œ„, ๊ทธ๋ฆฌ๊ณ  ๊ท ์—ด์— ์˜ํ•œ ๋ณต๋ถ€์†์ƒ๊ตฌ๊ฐ„๊ณผ ๊ด€๊ณ„์žˆ๋Š” ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์˜ ์†Œ์„ฑํžŒ์ง€ ์œ„์น˜๋กœ ์ •์˜ํ•˜์˜€๋‹ค. ๋Œ€๋ถ€๋ถ„์˜ ์‹คํ—˜์ฒด๋Š” ๋ฏธ์„ธ๊ท ์—ด์ด ๋ณต๋ถ€ ๋„“์€ ๊ตฌ๊ฐ„์— ๊ฑธ์ณ ๊ทธ ๋ฒ”์œ„๋ฅผ ๋„“ํ˜€๊ฐ€๋ฉด์„œ ๊ฐ๋„๊ฐ€ ์ž‘์•„์ง€๋‹ค๊ฐ€ ํŠน์ • ๊ท ์—ดํญ์ด ์ปค์ง€๋ฉด์„œ ์ตœ๋Œ€ ๊ฐ•๋„์— ๋„๋‹ฌํ•œ ํ›„ ๋ถ€์žฌ ๋ณ€ํ˜•์ด ์ปค์ง€๋ฉด์„œ ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์— ์†Œ์„ฑํžŒ์ง€๊ฐ€ ๋ฐœ์ƒํ•˜๋ฉด์„œ ์ตœ์ข… ํŒŒ๊ดด๋˜์—ˆ๋‹ค. ์˜ˆ์™ธ์ ์ธ ๊ฒฝ์šฐ๋กœ๋Š” ์•ž์„œ ์–ธ๊ธ‰ํ•œ ๋ฐ”์™€ ๊ฐ™์ด, 2-S35-B๊ฐ€ ์ง€์ ๋ถ€๊นŒ์ง€ ๋ณต๋ถ€ ๋ณ€ํ˜•์ด ํ™•๋Œ€๋˜๋ฉด์„œ ์ง€์ ๋ถ€ ๋ณต๋ถ€ ์ธ์žฅ๋ณ€ํ˜•์— ์˜ํ•œ ํŒŒ๊ดด๊ฐ€ ์ผ์–ด๋‚ฌ๋Š”๋ฐ ์ด๋กœ ์ธํ•ด ์ตœ๋Œ€ ํ•˜์ค‘์ด ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค.

์ฃผ๊ท ์—ด์€ Fig. 6์— ๊ตต์€ ์„ ์œผ๋กœ ์ฃผ๊ท ์—ด ํญ์ด ๋ฒŒ์–ด์งˆ ๋•Œ์˜ ํ•˜์ค‘์ด ํ•จ๊ป˜ ํ‘œ์‹œ๋˜์–ด ์žˆ๊ณ  ์ดˆ๊ธฐ ๊ท ์—ด ๋ฐœ์ƒ ์œ„์น˜ ๋ฐ ํ•˜์ค‘๋„ ๋‚˜ํƒ€๋‚˜์žˆ๋‹ค. ๋ชจ๋“  ์‹คํ—˜์ฒด์˜ ๋ณต๋ถ€์—์„œ ๊ตญ๋ถ€ ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์ด ๋‚˜ํƒ€๋‚ฌ๋Š”๋ฐ, ๊ท ์—ด ์ง‘์ค‘ํ˜„์ƒ์ด ์ผ์–ด๋‚˜๋Š” ๊ท ์—ด์„ ์ฃผ๊ท ์—ด๋กœ ์ •์˜ํ•˜์˜€๋‹ค. Fig. 6์˜ ์„ธ๋กœ ๋ณด์กฐ์„ ์€ /Resources/kci/JKCI.2017.29.1.053/images/PICA727.gif์˜ ๊ฐ„๊ฒฉ์œผ๋กœ ๊ทธ๋ ค์ ธ ์žˆ๋‹ค. ๋ณด์กฐ์„ ์— ๋น„์ถ”์–ด ๋ณด๋ฉด ๋ณต๋ถ€ ๋Œ€๊ฐ ๊ท ์—ด ๋ถ„ํฌ๋Š” ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ, /Resources/kci/JKCI.2017.29.1.053/images/PICA757.gif์—์„œ๋ถ€ํ„ฐ /Resources/kci/JKCI.2017.29.1.053/images/PICA797.gif์ธ ๊ตฌ๊ฐ„์— ๊ฑธ์ณ ๋ถ„ํฌํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ดˆ๊ธฐ ๊ท ์—ด๊ณผ ์ฃผ๊ท ์—ด์˜ ์œ„์น˜๋Š” ๋™์ผํ•˜์ง€ ์•Š์•˜๋‹ค. ์ฃผ๊ท ์—ด์€ ๋ฏธ์„ธ๊ท ์—ด ๊ตฌ๊ฐ„ ์ค‘ ์ž„์˜์˜ ์œ„์น˜์—์„œ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ, ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์˜ ์†Œ์„ฑํžŒ์ง€๋Š” ๊ฐ€๋ ฅ๋ถ€๋กœ๋ถ€ํ„ฐ /Resources/kci/JKCI.2017.29.1.053/images/PICA7C7.gif ๋–จ์–ด์ง„ ์ ์—์„œ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ์ตœ๋Œ€ ํ•˜์ค‘๋„๋‹ฌ ์ดํ›„ ์ฃผ ๊ท ์—ด ํญ์€ ๊ณ„์† ์ฆ๊ฐ€ํ•˜์ง€ ์•Š๊ณ , ์ฃผ๊ท ์—ด์— ๋‚˜๋ž€ํ•˜๊ฒŒ ๋ฐœ์ƒํ•œ ์••์ถ•์ŠคํŠธ๋Ÿฟ์ด ์ผ๋ถ€ ์••๊ดดํ•˜๋ฉด์„œ ๋ถ€์žฌ๊ฐ€ ์™„์ „ํžˆ ํŒŒ๊ดด๋˜์—ˆ๋‹ค. ๋˜ํ•œ ๊ท ์—ด๋ถ„ํฌ ๋ฒ”์œ„ ๋ฐ ๋ฏธ์„ธ๊ท ์—ด ์ˆ˜, ์ฃผ๊ท ์—ด๊ฐ๋„๋Š” ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ธ ๊ฒฝ์šฐ์— ๋น„ํ•ด ์ž‘์•˜๋‹ค.

์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ด๊ณ  ์œ ํšจ๋†’์ด๊ฐ€ 445mm์ธ ๊ฒฝ์šฐ๋Š” ์ฃผ๊ท ์—ด์˜ ํญ์ด ์ตœ๊ณ  ํ•˜์ค‘ ๋„๋‹ฌ ํ›„ ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์˜ ์†Œ์„ฑํžŒ์ง€๊ฐ€ ํฌ๊ฒŒ ๊บพ์ด๋Š” ์ตœ์ข… ํŒŒ๊ดด์— ์ด๋ฅด๋Ÿฌ์„œ๋Š” ์ฃผ๊ท ์—ด ํญ์ด 2mm๋ฅผ ๋„˜์„ ์ •๋„๋กœ ์ปค์ง€๋ฉด์„œ ๋ถ€์žฌ ์ „์ฒด์— ํฐ ๋ณ€ํ˜•์„ ์ˆ˜๋ฐ˜ํ•˜์˜€๋‹ค. ๋ณต๋ถ€ ๋Œ€๊ฐ ๊ท ์—ด์€ /Resources/kci/JKCI.2017.29.1.053/images/PICA7F6.gif์—์„œ๋ถ€ํ„ฐ /Resources/kci/JKCI.2017.29.1.053/images/PICA817.gif์ธ ๊ตฌ๊ฐ„์— ๊ฑธ์ณ ๋ถ„ํฌํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ฃผ๊ท ์—ด์˜ ์œ„์น˜๋Š” ๊ท ์—ด๋ถ„ํฌ ๊ตฌ๊ฐ„ ๋‚ด ์ž„์˜์˜ ์œ„์น˜์—์„œ ๋ฐœ์ƒํ•˜์˜€์œผ๋‚˜ ๊ทธ ๊ฐ๋„๊ฐ€ ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ์— ๋น„ํ•ด ์ž‘๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๋ฏธ์„ธ๊ท ์—ด์— ์˜ํ•œ ๋ณต๋ถ€ ์†์ƒ ๊ตฌ๊ฐ„์ด ํฌ๊ฒŒ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ ์ฃผ๊ท ์—ด์€ ๋ณต๋ถ€ ์†์ƒ ๊ตฌ๊ฐ„์˜ ๋Œ€๊ฐ์„  ๋ฐฉํ–ฅ์œผ๋กœ ๋‚˜ํƒ€๋‚˜ ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.5์ธ ๊ฒฝ์šฐ๋ณด๋‹ค ์ฃผ๊ท ์—ด ๊ฐ๋„๊ฐ€ ์ž‘์•„์ง€๋Š” ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜€๋‹ค. ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์˜ ์†Œ์„ฑํžŒ์ง€๋Š” ์ง€์ ๋ถ€์—์„œ /Resources/kci/JKCI.2017.29.1.053/images/PICA837.gif ๋–จ์–ด์ง„ ์œ„์น˜์— ๋ฐœ์ƒํ•˜์˜€๊ณ , 1-S35์™€ 2-S35์—์„œ๋Š” ์†Œ์„ฑํžŒ์ง€์—์„œ์˜ ํŒŒ๊ดด์™€ ๋™์‹œ์— ๊ฐ€๋ ฅ๋ถ€ ํ•˜๋‹จ ๋ณต๋ถ€์— ์ˆ˜์ง๋ฐฉํ–ฅ์œผ๋กœ ์••๊ดด๊ฐ€ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

์ „๋‹จ ๊ฒฝ๊ฐ„๋น„๊ฐ€ 3.5์ด๊ณ  ์œ ํšจ๋†’์ด๊ฐ€ 625mm์ธ ๊ฒฝ์šฐ ์ค‘ 1-S35-B์™€ 3-S35-B๋Š” ์ฃผ ๊ท ์—ด์˜ ํญ์ด ์ตœ๊ณ  ํ•˜์ค‘ ๋„๋‹ฌ ํ›„ ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์˜ ์†Œ์„ฑํžŒ์ง€๊ฐ€ ํฌ๊ฒŒ ๊บพ์ด๋Š” ์ตœ์ข… ํŒŒ๊ดด์— ์ด๋ฅด๋Ÿฌ์„œ๋Š” ์ฃผ ๊ท ์—ด ํญ์ด 10mm๋ฅผ ๋„˜์„ ์ •๋„๋กœ ๋งค์šฐ ํฌ๊ฒŒ ๋ฒŒ์–ด์ง€๊ฑฐ๋‚˜ 1-S35-B์™€ ๊ฐ™์ด ๋™์‹œ์— ์—ฌ๋Ÿฌ ๊ฐœ์˜ ์ฃผ ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜๋ฉด์„œ ๋ณด ์ „์ฒด์— ํฐ ๋ณ€ํ˜•์„ ์ˆ˜๋ฐ˜ํ•˜์˜€๋‹ค. ๋ณต๋ถ€ ๋Œ€๊ฐ ๊ท ์—ด์€ /Resources/kci/JKCI.2017.29.1.053/images/PICA867.gif์—์„œ๋ถ€ํ„ฐ /Resources/kci/JKCI.2017.29.1.053/images/PICA897.gif์ธ ๊ตฌ๊ฐ„์— ๊ฑธ์ณ ๋ถ„ํฌํ•˜์˜€๊ณ , ์ƒ๋ถ€ ํ”Œ๋žœ์ง€์˜ ์†Œ์„ฑํžŒ์ง€๋Š” ์ง€์ ๋ถ€์—์„œ /Resources/kci/JKCI.2017.29.1.053/images/PICA8B7.gif ์ด๋‚ด๋กœ ์œ ํšจ๋†’์ด๊ฐ€ 445mm์ธ ๊ฒฝ์šฐ๋ณด๋‹ค ๊ทธ ์œ„์น˜๊ฐ€ ๊ฐ€๋ ฅ๋ถ€์— ๊ฐ€๊นŒ์› ๋‹ค. ๋ณต๋ถ€ ์†์ƒ๊ตฌ๊ฐ„์€ ๊ฐ€๋ ฅ๋ถ€์—์„œ ์†Œ์„ฑํžŒ์ง€ ์œ„์น˜๊นŒ์ง€ ํ‰ํ–‰ ์‚ฌ๋ณ€ํ˜•์˜ ํ˜•ํƒœ๋กœ ๊ด€์ฐฐ๋˜์—ˆ์œผ๋ฉฐ, ์ตœ๋Œ€ ํ•˜์ค‘ ๋„๋‹ฌ ์ดํ›„ ๋Œ€๊ฐ ๊ท ์—ด์€ ์ง€์ ๋ถ€๊นŒ์ง€ ํ•˜๋ถ€ ํ”Œ๋žœ์ง€๋ฅผ ๋”ฐ๋ผ ์†์ƒ๊ตฌ๊ฐ„์ด ์ ์ฐจ ๋„“์–ด์ง€์ง€๋งŒ ์•„์น˜ํ˜•ํƒœ๋กœ ๊ทธ ๋†’์ด๊ฐ€ ์ค„์–ด๋“ค์—ˆ๋‹ค. 2-S35-B๋Š” ๋ณต๋ถ€ ์†์ƒ๊ตฌ๊ฐ„์ด ๊ฐ€๋ ฅ๋ถ€์™€ ์ง€์ ๋ถ€์— ๊ฑธ์ณ ๋„“๊ฒŒ ๋ถ„ํฌํ•˜์˜€์œผ๋ฉฐ ํœจ ๊ท ์—ด๊ณผ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ์—ฐ๊ฒฐ๋˜๋ฉด์„œ ์ฃผ๊ท ์—ด๋กœ ์ง„์ „๋˜์–ด ๋ณ€ํ˜•์ด ํ•˜๋ถ€์— ์ ๋ฆฌ๋ฉด์„œ ์ตœ๋Œ€ ํ•˜์ค‘์— ๋„๋‹ฌํ•˜๊ธฐ ์ „๋ถ€ํ„ฐ ์ง€์ ๋ถ€ ๋ณต๋ถ€๊นŒ์ง€ ๊ท ์—ด์ด ํฌ๊ฒŒ ์ง„์ „๋˜์–ด ์ตœ๋Œ€ ํ•˜์ค‘ ๋„๋‹ฌ ์‹œ ๊ฐ€๋ ฅ๋ถ€ ๊ทผ์ฒ˜ ์ฃผ ๊ท ์—ด ์™ธ์—๋„ ์ง€์ ๋ถ€์— ์ˆ˜์ง ๋ฐฉํ–ฅ ๋ณ€ํ˜•์ด ํ™•๋Œ€๋˜๋ฉด์„œ ์ตœ์ข… ํŒŒ๊ดด๊ฐ€ ๋™์‹œ์— ์ผ์–ด๋‚ฌ๋‹ค.

3.3 ๋ณต๋ถ€ ์ฃผ์ธ์žฅ ๊ฐ๋„ ๋ฐ ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ ๊ตฌ๊ฐ„

์ฃผ์‘๋ ฅ ๋ฐฉํ–ฅ /Resources/kci/JKCI.2017.29.1.053/images/PICA8D7.gif์€ LVDT๋กœ ๊ณ„์ธกํ•œ ํ‰๊ท ๋ณ€ํ˜•๋ฅ ์— ์˜ํ•œ ์ฃผ๋ณ€ํ˜• ๋ฐฉํ–ฅ๊ณผ ์ฝ˜ํฌ๋ฆฌํŠธ 3์ถ• ๊ฒŒ์ด์ง€๋กœ ๊ณ„์ธกํ•œ ๋ณ€ํ˜•๋ฅ ์— ์˜ํ•œ ์ฃผ๋ณ€ํ˜• ๋ฐฉํ–ฅ์„ ๋ชจ๋‘ ๊ณ ๋ คํ•˜์—ฌ ๋ชจ์–ด ์›์— ์˜ํ•ด ์‚ฐ์ •ํ•˜์˜€๋‹ค. ์ผ๋ฐ˜์ ์œผ๋กœ ์ฃผ์‘๋ ฅ๋ฐฉํ–ฅ์€ ์ฃผ๋ณ€ํ˜• ๋ฐฉํ–ฅ์— ์ง€์—ฐ๋˜์–ด ๋‚˜ํƒ€๋‚œ๋‹ค๊ณ  ์•Œ๋ ค์ ธ ์žˆ์ง€๋งŒ ์—ฌ๊ธฐ์„œ๋Š” ์ด๋ฅผ ๋ฌด์‹œํ•˜๊ณ  ์ฃผ๋ณ€ํ˜• ๋ฐฉํ–ฅ๊ณผ ์ฃผ์‘๋ ฅ ๋ฐฉํ–ฅ์€ ๊ฐ™๋‹ค๊ณ  ๊ฐ€์ •, Fig. 7๊ณผ ๊ฐ™์ด /Resources/kci/JKCI.2017.29.1.053/images/PICA8E8.gif-/Resources/kci/JKCI.2017.29.1.053/images/PICA937.gif ๊ด€๊ณ„๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. LVDT์— ์˜ํ•œ ๊ฒฐ๊ณผ์™€ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฒŒ์ด์ง€์— ์˜ํ•œ ๊ฒฐ๊ณผ๋Š” ๋น„์Šทํ•œ ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, ์ด๋Š” ๋ฏธ์„ธ๊ท ์—ด์€ ๊ทธ ํญ์ด ์ž‘์œผ๋ฏ€๋กœ ์ฃผ๊ท ์—ด ๋ฐœ์ƒ ์ „์˜ ๊ฒฝํ–ฅ์„ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฒŒ์ด์ง€๋กœ๋„ ์ธก์ •ํ•  ์ˆ˜ ์žˆ๊ธฐ ๋•Œ๋ฌธ์ธ ๊ฒƒ์œผ๋กœ ์‚ฌ๋ฃŒ๋œ๋‹ค. Fig. 7์˜ ์ฃผ๋ณ€ํ˜• ๋ฐฉํ–ฅ์€ ์‹คํ—˜์ฒด์˜ ์ขŒ, ์šฐ ์ค‘ ์ตœ๋Œ€ํ•˜์ค‘์„ ๊ฒฐ์ •ํ•˜๋Š” ์ฃผ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์ชฝ์˜ ๋ฐ์ดํ„ฐ๋ฅผ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค. S25์™€ S35 ์‹คํ—˜์ฒด์˜ ๊ฒฝ์šฐ ๊ท ์—ด ๋ฐœ์ƒ ์ดํ›„ ์ฃผ์ธ์žฅ ๊ฐ๋„๊ฐ€ ๊ธ‰๊ฒฉํ•˜๊ฒŒ ๊ฐ์†Œํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์ด๋Š” ๋ฐ˜๋ฉด, S35-B ์‹คํ—˜์ฒด๋Š” ๊ท ์—ด ๋ฐœ์ƒ ์ดํ›„์—๋„ ์ฃผ์ธ์žฅ ๊ฐ๋„๊ฐ€ ์™„๋งŒํ•˜๊ฒŒ ๊ฐ์†Œํ•˜์˜€๋‹ค. ์ตœ๋Œ€ ํ•˜์ค‘์—์„œ์˜ ๊ฐ๋„๋Š” S25 ์‹คํ—˜์ฒด๊ฐ€ ์•ฝ 25ยฐ๋กœ S35, S35-B ์‹คํ—˜์ฒด์— ๋น„ํ•ด ๋‹ค์†Œ ๋†’์•˜์œผ๋ฉฐ, S35 ์‹คํ—˜์ฒด๋Š” ์•ฝ 20ยฐ๊นŒ์ง€ ๊ฐ์†Œํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2017.29.1.053/images/Figure_CONCRETE_29_01_06_F7.jpg

Fig. 7 Principal strain of test specimens depending on a/d ratio and effective depth

/Resources/kci/JKCI.2017.29.1.053/images/PICA957.gif๋Š” ๋ณต๋ถ€์— ํ˜•์„ฑ๋œ ํ‰ํ–‰์‚ฌ๋ณ€ํ˜• ํ˜•ํƒœ์˜ ๊ท ์ผํ•œ ํฌ๊ธฐ์˜ ์‘๋ ฅ์žฅ ํ˜น์€ ์†์ƒ๊ตฌ๊ฐ„์˜ ๋Œ€๊ฐ์„  ๊ฐ๋„๋กœ ๋ณผ ์ˆ˜ ์žˆ๋‹ค. ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์žˆ๋Š” ๊ฒฝ์šฐ, ์œ ๋กœ์ฝ”๋“œ14) ๋ฐ fib model code 201019)์—์„œ๋Š” ๋ณต๋ถ€์— ํ˜•์„ฑ๋œ ์••์ถ• ์ŠคํŠธ๋Ÿฟ์ด ํšŒ์ „ํ•˜๋ฉด์„œ ์ŠคํŠธ๋Ÿฟ ๋ณ€ํ˜• ํ•œ๊ณ„ ํ˜น์€ ๊ฐ•๋„ ํ•œ๊ณ„์— ์˜ํ•ด ํ•œ๊ณ„์ƒํƒœ์— ๋„๋‹ฌํ•˜๋Š” ๊ฒƒ์œผ๋กœ ์ „๋‹จ๊ฐ•๋„๋ฅผ ์ •์˜ํ•˜๊ณ  ์žˆ๋Š”๋ฐ, ์ด๋Ÿฌํ•œ ๊ฐœ๋…์„ UHPFRC์— ์ ์šฉ์‹œํ‚ค๋ฉด ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์„ค๋ช…ํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ท ์—ด๋ฐœ์ƒ ์ „ ๋ณต๋ถ€ ์ฃผ์‘๋ ฅ๋ฐฉํ–ฅ์€ 45ยฐ๋กœ ์ผ์ •ํ•˜๋ฉฐ, ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜๊ธฐ ์‹œ์ž‘ํ•˜๋ฉด ๊ฐ•์„ฌ์œ ์— ์˜ํ•œ ์ธ์žฅ๊ฒฝํ™”๊ฑฐ๋™์— ์˜ํ•ด ๋ฏธ์„ธ๊ท ์—ด์ด ๋ณต๋ถ€์— ๋„“๊ฒŒ ๋ถ„ํฌํ•˜๊ฒŒ ๋˜๋Š”๋ฐ, ์ด ๋•Œ ์ฃผ์‘๋ ฅ๋ฐฉํ–ฅ์€ ์ ์ฐจ ๊ฐ์†Œํ•˜๊ฒŒ ๋œ๋‹ค. ๋ฏธ์„ธ๊ท ์—ด์ด ํ•œ๊ณ„๋ณ€ํ˜•์ƒํƒœ์—์„œ ๋Œ€๊ท ์—ด๋กœ ์ง‘์ค‘๋˜๋ฉด ๋ณต๋ถ€ ์ฃผ์‘๋ ฅ๋ฐฉํ–ฅ์€ ์ผ์ •ํ•˜๊ฒŒ ์œ ์ง€๋˜๋Š” ๊ฒฝํ–ฅ์„ ๊ฐ€์ง„๋‹ค. ์ด๋Š” ๋ถ€์žฌ ์ „์ฒด ๋ณ€ํ˜•์ด ๋ณต๋ถ€๊ฐ€ ์•„๋‹Œ ํ”Œ๋žœ์ง€ ๋“ฑ ๋‹ค๋ฅธ ๋ถ€๋ถ„์œผ๋กœ ์ „์ด๋˜๋Š” ๊ณผ์ •์ด๋ผ๊ณ ๋„ ์„ค๋ช…๋  ์ˆ˜ ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ์ฃผ๊ท ์—ด์— ์˜ํ•œ ์ตœ๋Œ€๊ฐ•๋„๋Š” ํ•œ๊ณ„๋ณ€ํ˜•์ƒํƒœ๋กœ ์ •์˜๋˜๋ฉฐ, ๋Œ€๊ท ์—ด ๋ฐœ์ƒ์—์„œ ํŒŒ๊ดด์— ์ด๋ฅด๋Š” ๊ตฌ๊ฐ„์€ ์žฌ๋ฃŒํŠน์„ฑ ๋ฐ ๋ถ€์žฌ์˜ ๊ธฐํ•˜ํ•™์ ์ธ ํ˜•ํƒœ์— ํฐ ์˜ํ–ฅ์„ ๋ฐ›๊ฒŒ ๋œ๋‹ค.

4. ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์˜์ „๋‹จ๊ฐ•๋„ ํ‰๊ฐ€

4.1 UHPFRC ์ „๋‹จ ๊ฐ•๋„ ํ‰๊ฐ€์‹

4.1.1 Recommendations for Design and Construction for UHPC, AFGC Setra

ํ”„๋ž‘์Šค ํ† ๋ชฉํ•™ํšŒ(AFGC)๋Š” ์••์ถ•๊ฐ•๋„ 150MPa ์ด์ƒ, ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„ 2% ์ด์ƒ์ธ UHPFRC์— ๋Œ€ํ•˜์—ฌ ์‹ (4-1)๊ณผ ๊ฐ™์ด ์ •์˜ํ•˜๊ณ  ์žˆ๋‹ค.12) ์ฒ ๊ทผ ์Šคํ„ฐ๋Ÿฝ๊ณผ ๊ฐ•์„ฌ์œ ๋กœ ๋ณด๊ฐ•๋œ UHPC ๋ณด์˜ ์ „๋‹จ๊ฐ•๋„๋Š” ์‹ (4-2)์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ๋‹จ๋ฉด์ด ์ง€์ง€ํ•˜๋Š” ๋ถ€๋ถ„, ์‹ (4-3)์˜ ์ฒ ๊ทผ์— ์˜ํ•ด ์ €ํ•ญํ•˜๋Š” ๋ถ€๋ถ„๊ณผ ์‹ (4-4)์˜ ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ์ €ํ•ญํ•˜๋Š” ๋ถ€๋ถ„์˜ ํ•ฉ์œผ๋กœ ๋‚˜ํƒ€๋‚œ๋‹ค. ํŠนํžˆ ์‹ (4-4)๋Š” ๋ถ€์žฌ์˜ ์‚ฌ์ธ์žฅ ๊ท ์—ด๋ถ€์—์„œ ๊ท ์—ด์— ์ˆ˜์ง๋ฐฉํ–ฅ์œผ๋กœ ๋ฐœํœ˜๋˜๋Š” ํ‰๊ท ์ธ์žฅ๊ฐ•๋„ /Resources/kci/JKCI.2017.29.1.053/images/PICA997.gif์— ์˜ํ•œ ์ „๋‹จ๊ฐ•๋„์ด๋‹ค. UHPFRC ์ž”๋ฅ˜ ์ธ์žฅ์‘๋ ฅ /Resources/kci/JKCI.2017.29.1.053/images/PICA9D6.gif์€ ์‹ (3)์— ์˜ํ•ด ๊ตฌํ•  ์ˆ˜ ์žˆ๋‹ค. ์ฃผ์‘๋ ฅ ๋ฐฉํ–ฅ /Resources/kci/JKCI.2017.29.1.053/images/PICA9E7.gif๋Š” ์‚ฌ์ธ์žฅ๊ท ์—ด๋ถ€์˜ ์ฃผ์‘๋ ฅ ๋ฐฉํ–ฅ์ด๊ณ , 30ยฐ๋ณด๋‹ค ์ž‘์„ ์ˆ˜ ์—†๋‹ค. ๊ธฐ์กด์—ฐ๊ตฌ์—์„œ๋Š” ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์Šค๊ฐ€ ์—†๋Š” ๋ถ€์žฌ์˜ ๊ฒฝ์šฐ /Resources/kci/JKCI.2017.29.1.053/images/PICAA36.gif๋ฅผ 40ยฐ๋กœ ๊ฐ€์ •ํ–ˆ์„ ๋•Œ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์ž˜ ์˜ˆ์ธกํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋ณด๊ณ ๋˜๊ณ  ์žˆ๋‹ค.2-4,21)

/Resources/kci/JKCI.2017.29.1.053/images/PICAA85.gif (4-1)

/Resources/kci/JKCI.2017.29.1.053/images/PICAAB5.gif (4-2)

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์ผ๋ณธ ํ† ๋ชฉํ•™ํšŒ(JSCE)23)์—์„œ๋„ UHPFRC ๋ถ€์žฌ ์„ค๊ณ„์— ๋Œ€ํ•œ ์ง€์นจ์ด ์žˆ์œผ๋ฉฐ ์‹ค๋ฌด์—์˜ ์ ์šฉ์‚ฌ๋ก€๊ฐ€ ๋งŽ์€ ๊ฒƒ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค. ์ด ์ง€์นจ์€ ์žฌ๋ฃŒ ์•ˆ์ „๊ณ„์ˆ˜ ์™ธ์— ๋ถ€์žฌ ์•ˆ์ „๊ณ„์ˆ˜๋ฅผ ์ถ”๊ฐ€๋กœ ๊ณ ๋ คํ–ˆ๋‹ค๋Š” ํŠน์ง•์ด ์žˆ์œผ๋‚˜, ๊ธฐ๋ณธ์ ์ธ ๋‚ด์šฉ์ด AFGC ์ œ์•ˆ์‹๊ณผ ์œ ์‚ฌํ•˜๋‹ค.

4.1.2 fib model code 2010 / DIN EN 1992-1-1

fib model code๋Š” ์„ฌ์œ ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ(FRC)์— ๋Œ€ํ•ด ์žฌ๋ฃŒ์˜ ๋ฌผ๋ฆฌ์  ์„ฑ์งˆ ๋ฐ ๋ถ€์žฌ ์„ค๊ณ„์— ๋Œ€ํ•ด ๋ณธ๋ฌธ์— ๋ณ„๋„์˜ ๋‹จ์›์„ ํ• ์• ํ•˜์—ฌ ๋‹ค๋ฃจ๊ณ  ์žˆ์œผ๋ฉฐ19) ์ œ์‹œ๋œ ๋‚ด์šฉ๋“ค์€ SFRC ์ ์šฉ์— ๊ฐ€์žฅ ์ ํ•ฉํ•˜์ง€๋งŒ UHPFRC์—๋„ ์ ์šฉํ•  ์ˆ˜ ์žˆ๋‹ค. ๋ฌผ๋ฆฌ์  ์„ฑ์งˆ์€ ์ธ์žฅ๊ฑฐ๋™์ด ๊ท ์—ด๋ฐœ์ƒ ํ›„ ์—ฐํ™”๊ฑฐ๋™์„ ๋ณด์ด๋Š” ์žฌ๋ฃŒ์™€ ๋ฏธ์„ธ๊ท ์—ด์ด ๋„“์€ ๊ตฌ๊ฐ„์— ๊ฑธ์ณ ๋ฐœ์ƒํ•˜๋ฉด์„œ ๊ฒฝํ™”๊ฑฐ๋™์„ ๋ณด์ด๋Š” ์žฌ๋ฃŒ์˜ ๋‘ ๊ฐ€์ง€๋กœ ๋‚˜๋‰˜๋ฉฐ, ์ธ์žฅ๊ฑฐ๋™์˜ ์ •์˜๋Š” ์•ž์„œ 2.3์ ˆ์—์„œ ์–ธ๊ธ‰ํ•œ ๋‚ด์šฉ๊ณผ ๊ฐ™๋‹ค. FRC ๋ถ€์žฌ์„ค๊ณ„๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” ๊ฒฝ์šฐ ์‹ (5)์™€ ๊ฐ™์ด ์ œ์‹œํ•˜๊ณ  ์žˆ๋‹ค. ์ด๋Š” ๋ณดํ†ต ์••์ถ•๊ฐ•๋„๋ฅผ ๊ฐ€์ง„ SFRC์—๋Š” ์œ ํšจํ•˜๋‚˜, UHPFRC์—๋Š” ์ ์šฉํ•˜๊ธฐ ํž˜๋“ค๊ณ , UHPFRC๋Š” ์‹ (4-1)์™€ ๊ฐ™์€ ํ˜•ํƒœ๋ฅผ ์‚ฌ์šฉํ•  ์ˆ˜ ์žˆ๋‹ค๊ณ  ํ•ด์„ค์— ์–ธ๊ธ‰ํ•˜๊ณ  ์žˆ๋‹ค.

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์‹ (5)๋Š” ์œ ๋กœ์ฝ”๋“œ์˜ ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„์‹๊ณผ ์œ ์‚ฌํ•˜๋‹ค. ํฌ๊ธฐํšจ๊ณผ ๊ณ„์ˆ˜/Resources/kci/JKCI.2017.29.1.053/images/PICABB3.gif๋Š” ์œ ๋กœ์ฝ”๋“œ์™€ ๋™์ผํ•˜๊ฒŒ /Resources/kci/JKCI.2017.29.1.053/images/PICABF2.gif์˜ ์ œํ•œ๊ฐ’์„ ์ ์šฉํ•˜๊ณ , ํœจ์ฒ ๊ทผ๋น„๋Š” ์œ ๋กœ์ฝ”๋“œ์—์„œ ์ƒํ•œ๊ฐ’ 0.02๋ฅผ ์ ์šฉํ•˜๋Š” ๊ฒƒ๊ณผ ๋‹ฌ๋ฆฌ ๋ณ„๋„์˜ ์ƒํ•œ๊ฐ’์„ ๋‘์ง€ ์•Š์•˜๋‹ค. ์—ฌ๊ธฐ์— ๋ณ„๋„๋กœ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ๋กœ์„œ /Resources/kci/JKCI.2017.29.1.053/images/PICAC42.gif๋ฅผ ๊ณ ๋ คํ•˜๊ณ  ์žˆ๋‹ค.

UHPFRC๋Š” ์œ ๋กœ์ฝ”๋“œ ์ ์šฉ๋ฒ”์œ„๋ฅผ ๋„˜์–ด์„œ๋Š” ์••์ถ•๊ฐ•๋„๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๊ณ , ๊ฐ•์„ฌ์œ  ์—ญํ• ์— ์˜ํ•ด ์‹ค์ œ๋กœ๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” ๊ฒฝ์šฐ์™€ ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์žˆ๋Š” ๊ฒฝ์šฐ์˜ ์ค‘๊ฐ„ ๋‹จ๊ณ„ ๊ฑฐ๋™์„ ๋ณด์ธ๋‹ค. ์ดˆ๊ธฐ ๊ท ์—ด ๋ฐœ์ƒ ํ›„ ๋ฏธ์„ธ๊ท ์—ด์ด ๋ถ„ํฌ๋˜๋Š” ์–‘์ƒ์€ ์ „๋‹จ์ฒ ๊ทผ์ด ๋ณด๊ฐ•๋œ ๊ฒฝ์šฐ์™€ ์œ ์‚ฌํ•˜์ง€๋งŒ, ์ตœ์ข… ํŒŒ๊ดด์‹œ์—๋Š” ๋ฏธ์„ธ๊ท ์—ด์ด ๋ถ„ํฌ๋œ ์†์ƒ๊ตฌ์—ญ ๋‚ด์—์„œ ์ฃผ๊ท ์—ด์— ์‘๋ ฅ์ด ์ง‘์ค‘๋˜๋ฉด์„œ ์ „๋‹จ์ฒ ๊ทผ์ด ๋ณด๊ฐ•๋˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์˜ ํŒŒ๊ดด์™€ ์œ ์‚ฌํ•œ ํ˜•ํƒœ๋ฅผ ๊ฐ€์ง„๋‹ค. ๋”ฐ๋ผ์„œ UHPFRC ๋ณด์˜ ์ „๋‹จ ๊ฐ•๋„๋ฅผ ์ •์˜ํ•  ๋•Œ ์‹ (5)๋ฅผ ๊ทธ๋Œ€๋กœ ์ ์šฉํ•˜๊ธฐ๋Š” ํž˜๋“ค์ง€๋งŒ, ๊ณ ๋ คํ•˜๊ณ  ์žˆ๋Š” ๋ณ€์ˆ˜๋“ค์— ๋Œ€ํ•ด ๊ฒ€ํ† ํ•ด ๋ณผ ํ•„์š”๊ฐ€ ์žˆ๋‹ค. ๋˜ํ•œ UHPFRC ๋ณด์˜ ์‹คํ—˜ ๋ฐ์ดํ„ฐ๊ฐ€ ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ์— ๋น„ํ•ด ํ›จ์”ฌ ์ ์€ ๊ฒƒ์„ ๊ณ ๋ คํ•ด ๋ณผ ๋•Œ, ๊ฒฝํ—˜์‹์„ ์ œ์‹œํ•˜๋Š” ๋ฐ์—๋Š” ์–ด๋ ค์›€์ด ์žˆ์œผ๋ฏ€๋กœ ๋ชจ๋ธ๋ง ๊ธฐ๋ฐ˜์˜ ์œ ๋กœ์ฝ”๋“œ ๊ธฐ๋ฐ˜์˜ fib model code ์‹์„ ๊ฒ€ํ† ํ•˜๋Š” ๊ฒƒ์€ ์ถฉ๋ถ„ํžˆ ํƒ€๋‹น์„ฑ์„ ๊ฐ€์ง„๋‹ค.

4.1.3 Sato, et. al. (TU Delft)

๋„ค๋œ๋ž€๋“œ์˜ Delft ๊ณต๋Œ€ ์—ฐ๊ตฌ์ง„์€ 2004๋…„๋ถ€ํ„ฐ ์ด๋ฃจ์–ด์ง„ ์ผ๋ จ์˜ ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ์••์ถ•๊ฐ•๋„ 140MPa, ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„ 0~1.6 %์ธ UHPFRC ๋ณด ์ „๋‹จ ๊ฐ•๋„์‹์„ ์ œ์•ˆํ•˜์˜€๋‹ค.24) ์ œ์•ˆ ๋ชจ๋ธ์€ ์œ ๋กœ์ฝ”๋“œ ์ค‘ ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์žˆ๋Š” ๋ณด์˜ ์ „๋‹จ๊ฐ•๋„์— ์‚ฌ์šฉ๋œ ๋ณ€๊ฐ ํŠธ๋Ÿฌ์Šค ๋ชจ๋ธ์— ๊ธฐ์ดˆํ•˜๊ณ  ์žˆ๋‹ค. ์œ ๋กœ์ฝ”๋“œ๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ํ•ญ๋ณตํ–ˆ์„ ๋•Œ์˜ ๊ฐ•๋„๋ฅผ ๊ธฐ๋ฐ˜์œผ๋กœ ํŠธ๋Ÿฌ์Šค์˜ ๊ฐ๋„๋ฅผ /Resources/kci/JKCI.2017.29.1.053/images/PICAC91.gif์œผ๋กœ ์ œํ•œํ•˜๊ณ  ์žˆ๋‹ค. ๋ฐ˜๋ฉด, ์‹ (6)์€ ์ž”๋ฅ˜ ์ธ์žฅ๊ฐ•๋„ /Resources/kci/JKCI.2017.29.1.053/images/PICACC1.gif๋ฅผ ๊ธฐ๋ฐ˜์œผ๋กœ ํŠธ๋Ÿฌ์Šค ๊ฐ๋„๋ฅผ /Resources/kci/JKCI.2017.29.1.053/images/PICAD10.gif์œผ๋กœ ํ™•์žฅํ•˜์—ฌ ์ œํ•œํ•˜๋Š” ํŠน์ง•์„ ๊ฐ€์ง„๋‹ค. ๋˜ํ•œ ๋‹จ๋ฉด์—์„œ์˜ ์œ ํšจ ํŒ”๊ธธ์ด /Resources/kci/JKCI.2017.29.1.053/images/PICAD30.gif๋ฅผ ๋‹จ๋ฉด ์ „์ฒด ๋†’์ด /Resources/kci/JKCI.2017.29.1.053/images/PICAD50.gif๋กœ ๋Œ€์ฒดํ•˜์˜€๋Š”๋ฐ, ์ด๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPFRC๊ฐ€ ํœจ์ฒ ๊ทผ ์•„๋ž˜ ๋ถ€๋ถ„์—์„œ๋„ ์ธ์žฅ๋ ฅ์— ์ €ํ•ญํ•จ์„ ๋ฐ˜์˜ํ•œ ๊ฒฐ๊ณผ์ด๋‹ค.

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์ƒ๊ธฐ ์ œ์•ˆ์‹ (4)~(6)์€ ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ๋ฐฐ๊ทผ๋˜์ง€ ์•Š์€ UHPFRC์˜ ์ „๋‹จ ๊ฐ•๋„์‹์ด๋ฉฐ, ์ฃผ์š”๋ณ€์ˆ˜๋Š” ์••์ถ•๊ฐ•๋„๊ฐ€ ์•„๋‹Œ UHPFRC ์ž”๋ฅ˜ ์ธ์žฅ๊ฐ•๋„๋ผ๋Š” ๊ณตํ†ต์ ์ธ ํŠน์ง•์„ ๊ฐ€์ง„๋‹ค. ์ด ์ค‘ ์‹ (4-4)์™€ (6)์€ ๊ฐ•์„ฌ์œ ์— ์˜ํ•œ ์ „๋‹จ ๋ณด๊ฐ•ํšจ๊ณผ๊ฐ€ ํŠธ๋Ÿฌ์Šค ๋ชจ๋ธ๋กœ ํ˜•์ƒํ™”์‹œํ‚ค๊ธฐ์— ์ถฉ๋ถ„ํ•˜๋‹ค๊ณ  ๋ณด๊ณ  ์žˆ์œผ๋ฉฐ, ํŠธ๋Ÿฌ์Šค ๊ฐ๋„์˜ ์ž„๊ณ„๊ฐ’์„ ๋‚ฎ์ถ”์–ด ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•˜๊ณ  ์žˆ๋‹ค. ํŠธ๋Ÿฌ์Šค ๊ฐ๋„์˜ ์ž„๊ณ„๊ฐ’ /Resources/kci/JKCI.2017.29.1.053/images/PICAE1D.gif์€ ๋ณธ ์—ฐ๊ตฌ์—์„œ์˜ ์‹คํ—˜๊ฒฐ๊ณผ ์ค‘ ์ฃผ๋ณ€ํ˜•๊ฐ๋„์™€ ๋น„๊ตํ•ด๋ณด๋ฉด ์ถฉ๋ถ„ํ•œ ํƒ€๋‹น์„ฑ์„ ๊ฐ€์ง„๋‹ค๊ณ  ๋ณผ ์ˆ˜ ์žˆ๋‹ค.

4.2 UHPFRC ์ „๋‹จ ๊ฐ•๋„ ํ‰๊ฐ€์‹๊ณผ ์‹คํ—˜๊ฒฐ๊ณผ ๋น„๊ต

4.1์—์„œ ์ œ์‹œ๋œ UHPFRC ๋ถ€์žฌ ์ „๋‹จ ๊ฐ•๋„ ์„ค๊ณ„์‹ 3๊ฐ€์ง€์— ๋Œ€ํ•ด ๊ณ„์‚ฐํ•œ ๊ฐ’์„ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๋น„๊ตํ•œ ๊ฐ’์„ Table 4์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. AFGC๋Š” ๋งคํŠธ๋ฆญ์Šค ๋ถ„๋‹ด๋ถ„ /Resources/kci/JKCI.2017.29.1.053/images/PICAE4D.gif์™€ ๊ฐ•์„ฌ์œ  ๋ถ„๋‹ด๋ถ„ /Resources/kci/JKCI.2017.29.1.053/images/PICAE5E.gif์˜ ํ•ฉ์œผ๋กœ ๋‚˜ํƒ€๋‚˜๊ณ  ์ด๋Š” ์‹คํ—˜๊ฒฐ๊ณผ ์ค‘ ๊ท ์—ด๋ฐœ์ƒ๊ฐ•๋„ /Resources/kci/JKCI.2017.29.1.053/images/PICAEAD.gif์™€ ๋ฏธ์„ธ๊ท ์—ด ๋ฐœ์ƒ ๊ตฌ๊ฐ„์— ์˜ํ•œ ๊ฐ•๋„ ์ฆ๋Œ€๋ถ„ /Resources/kci/JKCI.2017.29.1.053/images/PICAEDD.gif๊ณผ ๋น„๊ตํ•  ์ˆ˜ ์žˆ๋‹ค. /Resources/kci/JKCI.2017.29.1.053/images/PICAEFD.gif๋Š” 40ยฐ๋กœ ๊ฐ€์ •ํ•˜์˜€๊ณ , ์ „์ฒด์ ์ธ ๊ฐ’์€ ์‹คํ—˜๊ฐ’์„ ํฌ๊ฒŒ ์ƒํšŒํ•œ๋‹ค. ํŠนํžˆ Fig. 8์—์„œ ํ™•์ธ๋˜๋Š” ๋ฐ”์™€ ๊ฐ™์ด ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„์™€ ์œ ํšจ๋†’์ด์— ๋Œ€ํ•ด ์‹คํ—˜๊ฐ’์ด ํฌ๊ฒŒ ์˜ํ–ฅ์„ ๋ฐ›๋Š”๋ฐ ๋ฐ˜ํ•˜์—ฌ ํ‰๊ฐ€์‹์—๋Š” ๋ฐ˜์˜์ด ๋˜์ง€ ์•Š์•„ ํŽธ์ฐจ๊ฐ€ ํฐ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜€๋‹ค.

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Table 4 Comparison between theoretical and empirical test results (unit: kN)

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Fig. 8 Strength predictions for test results according to (a) shear span ratio and (b) effective depth

fib model code๋Š” ์ฃผ์–ด์ง„ ์‹ (5)์—์„œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ๋Š” ๊ทธ๋Œ€๋กœ ์ ์šฉํ•˜๋˜, ํฌ๊ธฐํšจ๊ณผ ๊ณ„์ˆ˜์™€ ํœจ์ฒ ๊ทผ๋น„๋Š” ์ˆ˜์ •๋œ ๊ฐ’์„ ์ ์šฉํ•˜์˜€๋‹ค. ํฌ๊ธฐํšจ๊ณผ์—์„œ ์œ ํšจ๋†’์ด์— ๋Œ€์‘๋˜๋Š” 200์ด๋ผ๋Š” ์ƒ์ˆ˜๋Š” ๊ตต์€ ๊ณจ์žฌ๋ฅผ ์‚ฌ์šฉํ•œ ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์—์„œ ์‘๋ ฅ๋ถ„์‚ฐ๋ฒ”์œ„์— ๋Œ€์‘๋˜๋Š” ๊ฐ’์œผ๋กœ ํ•ด์„๋  ์ˆ˜ ์žˆ๋Š”๋ฐ, ์ด๋ฅผ UHPFRC์˜ ํŠน์„ฑ๊ธธ์ด /Resources/kci/JKCI.2017.29.1.053/images/PICAF3D.gif๋ฅผ ๋ณด์ˆ˜์ ์œผ๋กœ ๊ณ ๋ คํ•˜์—ฌ 1000์œผ๋กœ ๋Œ€์ฒดํ•˜์˜€๋‹ค. ํœจ์ฒ ๊ทผ๋น„์˜ ์ƒํ•œ๊ฐ’์€ /Resources/kci/JKCI.2017.29.1.053/images/PICAF6C.gif๋กœ ์žฌ๋ฃŒ ์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ์ธ์žฅ๊ฐ•๋„๋น„๋กœ ์ œํ•œํ•˜์˜€๋‹ค. ์ด๋Š” UHPFRC์˜ ํœจ๊ฑฐ๋™์ด ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„์— ํฌ๊ฒŒ ์˜ํ–ฅ์„ ๋ฐ›๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ํœจ๊ท ์—ด์ด ์ธ์žฅ๋‹จ์— ๊ณ ๋ฅด๊ฒŒ ๋ถ„ํฌํ•˜์—ฌ ์ฒ ๊ทผ์ธ์žฅ๋ ฅ์— ์˜ํ•œ ๊ฐ•๋„๋งŒ ๊ณ ๋ คํ•˜๋Š” ๊ฒƒ์ด ๊ฐ€๋Šฅํ•œ ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์™€ ๋‹ฌ๋ฆฌ, UHPFRC๋Š” ์ฒ ๊ทผ๊ณผ UHPFRC ๋ถ€์ฐฉ๊ฐ•๋„๊ฐ€ ๋งค์šฐ ํฌ๊ณ  ํœจ๊ฑฐ๋™ ๋˜ํ•œ ๊ตญ๋ถ€๊ท ์—ด์— ์˜ํ•œ ๊ฐ•์ฒด๊ฑฐ๋™์— ๊ฐ€๊นŒ์šด ํ˜•ํƒœ๋ฅผ ๊ฐ€์ง€๊ณ  ์ฃผ๊ท ์—ด์—์„œ ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„์˜ ์ €ํ•ญ์ด ์ „์ฒด ๊ฑฐ๋™์„ ์ง€๋ฐฐํ•˜๋Š” ํŠน์ง•์„ ๊ฐ€์ง„๋‹ค. ์ƒ๊ธฐ ๋‘ ๊ฐ€์ง€ ๋ณ€์ˆ˜๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๊ณ„์‚ฐํ•œ ๊ฒฐ๊ณผ๋Š” Table 4์™€ ๊ฐ™๋‹ค. AFGC ํ‰๊ฐ€์‹๊ณผ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ ์‹คํ—˜๊ฐ’์„ ์ƒํšŒํ•˜๊ณ  ๊ทธ ์ •๋„๋„ ํฌ๊ฒŒ ์ฐจ์ด๊ฐ€ ๋‚˜์ง€ ์•Š์ง€๋งŒ Fig. 8์—์„œ ๋ณด๋Š” ๋ฐ”์™€ ๊ฐ™์ด ์‹คํ—˜๋ณ€์ˆ˜์— ๋Œ€ํ•œ ํŽธ์ฐจ๊ฐ€ ํฌ๊ฒŒ ์ค„์–ด๋“  ๊ฒƒ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. Table 3์˜ ํ‰๊ท ์— ๋Œ€ํ•œ ํŽธ์ฐจ๋„ AFGC ํ‰๊ฐ€์‹์€ 0.42, fib model code ํ‰๊ฐ€์‹์€ 0.27๋กœ ํฌ๊ฒŒ ์ค„์–ด๋“  ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜€๋‹ค.

๋งˆ์ง€๋ง‰์œผ๋กœ Delft ์—ฐ๊ตฌ์ง„์ด ์ œ์•ˆํ•œ ํ‰๊ฐ€์‹ (6)๋ฅผ ์ ์šฉํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•˜์˜€๋‹ค. ์—ฌ๊ธฐ์„œ /Resources/kci/JKCI.2017.29.1.053/images/PICAF7D.gif๋Š” ์‹คํ—˜๊ฒฐ๊ณผ์—์„œ ์–ป์€ ์ตœ๋Œ€ํ•˜์ค‘์— ๋„๋‹ฌํ–ˆ์„ ๋•Œ์˜ ์ฃผ๋ณ€ํ˜• ๊ฐ๋„ /Resources/kci/JKCI.2017.29.1.053/images/PICAF9D.gif๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ์ž”๋ฅ˜์ธ์žฅ๊ฐ•๋„ /Resources/kci/JKCI.2017.29.1.053/images/PICAFCD.gif๋Š” /Resources/kci/JKCI.2017.29.1.053/images/PICAFFD.gif๋ฅผ ์ ์šฉํ•˜์˜€๋‹ค. ์ด๋Š” ๋ถ€์žฌ ์‹คํ—˜ ๊ฒฐ๊ณผ๊ฐ’์„ ์ ์šฉํ•˜์—ฌ ๋น„๊ตํ•œ ๊ฒƒ์œผ๋กœ ์„ค๊ณ„์‹๊ณผ๋Š” ์ฐจ์ด๊ฐ€ ์žˆ์–ด Fig. 8์— ํ•จ๊ป˜ ๋น„๊ตํ•˜์ง€ ์•Š์•˜๋‹ค. ๋‹จ, ํ‰๊ฐ€์‹์— ๋Œ€ํ•œ ์‹คํ—˜๊ฒฐ๊ณผ๋น„์˜ ํ‰๊ท ๊ฐ’์ด 1.10, ํŽธ์ฐจ 0.21๋กœ ๋น„๊ต์  ์ •ํ™•ํ•˜๊ฒŒ ์˜ˆ์ธกํ•˜๊ณ  ์žˆ์–ด ์‹ (6)์˜ ๋ชจ๋ธ์˜ ํƒ€๋‹น์„ฑ์ด ์žˆ๋‹ค๊ณ  ํŒ๋‹จํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์•ž์„œ ์–ธ๊ธ‰ํ•œ ๋ฐ”์™€ ๊ฐ™์ด ํฌ๊ธฐํšจ๊ณผ, ์•„์น˜ํšจ๊ณผ, ํœจ์ฒ ๊ทผ๋น„ ๋“ฑ ๋ถ€์žฌ์˜ ๊ธฐํ•˜ํ•™์  ํ˜•์ƒ์ด ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์ด /Resources/kci/JKCI.2017.29.1.053/images/PICB01D.gif์— ํฌํ•จ๋˜์–ด ์žˆ์œผ๋ฏ€๋กœ, ์„ค๊ณ„์‹์œผ๋กœ ์‚ฌ์šฉํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” UHPFRC์˜ ์žฌ๋ฃŒ์  ์„ฑ์งˆ ๋ฐ ๋ถ€์žฌ ํ˜•์ƒ์„ ๋ฐ˜์˜ํ•  ์ˆ˜ ์žˆ๋„๋ก /Resources/kci/JKCI.2017.29.1.053/images/PICB05D.gif์— ๋Œ€ํ•œ ๋ณ„๋„์˜ ๋ชจ๋ธ๋ง์ด ํ•„์š”ํ•˜๋‹ค.

5. ๊ฒฐ    ๋ก 

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” UHPFRC ๋ณด์— ๋Œ€ํ•˜์—ฌ ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„, ์œ ํšจ๋†’์ด, ์žฌ๋ฃŒ์ธ์žฅ๊ฐ•๋„๋ฅผ ๋ณ€์ˆ˜๋กœ ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์ด๋ฅผ ํ†ตํ•ด UHPFRC ์ „๋‹จ๋ถ€์žฌ์˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ๊ธฐ์กด ์ œ์•ˆ์‹๊ณผ ๋น„๊ตํ•˜์—ฌ ์ œ์•ˆ์‹์ด ๋ถ€์žฌ๊ฑฐ๋™์„ ํšจ๊ณผ์ ์œผ๋กœ ๋ฐ˜์˜ํ•˜๊ณ  ์žˆ๋Š”์ง€ ๊ฒ€ํ† ํ•˜์˜€๋‹ค.

1)๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•ํšจ๊ณผ์˜ ๋ฐ˜์˜์„ ์œ„ํ•ด ๋…ธ์น˜๊ฐ€ ์žˆ๋Š” ํœจ์‹คํ—˜๊ณผ ์ง์ ‘์ธ์žฅ์‹คํ—˜์„ ๋น„๊ตํ•˜์—ฌ UHPFRC ์žฌ๋ฃŒ ์ธ์žฅ๊ฐ•๋„๋ฅผ ์ •์˜ํ•จ์— ์žˆ์–ด ์‹คํ—˜๋ฒ• ๋ฐ ๊ฒฐ๊ณผ ๋ถ„์„๋ฒ•์„ ๋น„๊ตํ•˜์˜€๋‹ค. ํœจ์‹คํ—˜ ๊ฒฐ๊ณผ๋ฅผ fib model code์—์„œ ์ œ์‹œ๋œ ์ธ์žฅ๊ฐ•๋„-CMOD ์„ ํ˜•๊ด€๊ณ„์‹์„ ์ด์šฉํ•ด์„œ ๊ตฌํ•œ ๊ฒฐ๊ณผ๊ฐ’์€ ์ง์ ‘์ธ์žฅ๊ฐ•๋„ ๊ฐ’๊ณผ ์ฐจ์ด๋Š” ์žˆ์œผ๋‚˜ ๋ถ€์žฌ ์„ค๊ณ„์‹์—๋Š” ์ ์šฉํ•˜๋Š”๋ฐ ๋ฌด๋ฆฌ๊ฐ€ ์—†๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

2)๋ณด ๋ถ€์žฌ ์‹คํ—˜ ๊ฒฐ๊ณผ ๋ณต๋ถ€ ๊ท ์—ด๋ฐœ์ƒ๊ฐ•๋„ ๋Œ€๋น„ ์ตœ๋Œ€ ์ „๋‹จ๊ฐ•๋„๋น„๋Š” ๋Œ€๋ถ€๋ถ„ 2.0๋ฅผ ์ƒํšŒํ•˜๋ฉฐ, ์ฃผ๋ณ€ํ˜•๊ฐ๋„ ์ธก์ •๊ฒฐ๊ณผ๋„ ๋ณต๋ถ€ ์‘๋ ฅ์žฅ์ด ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ๋ฅผ ํ†ตํ•ด ์•ˆ์ •์ ์œผ๋กœ ๊ฐ์†Œํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. UHPFRC ์ „๋‹จ๋ถ€์žฌ๋Š” ์ „๋‹จ๋ณด๊ฐ•๊ทผ ์—†์ด ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ•๋งŒ์œผ๋กœ๋„ ๋ฏธ์„ธ๊ท ์—ด์˜ ํ™•์žฅ์„ ํ†ตํ•ด ๋ณต๋ถ€ ์‘๋ ฅ์žฌ๋ถ„๋ฐฐ๊ฐ€ ํšจ๊ณผ์ ์œผ๋กœ ์ผ์–ด๋‚จ์„ ํ™•์ธํ•˜์˜€๋‹ค.

3)๋ชจ๋“  ์‹คํ—˜์ฒด์˜ ํŒŒ๊ดด๋ชจ๋“œ๋Š” ๋ณต๋ถ€ ์‚ฌ์ธ์žฅํŒŒ๊ดด๋กœ ๋™์ผํ•˜์˜€๊ณ , ์ด๋Ÿฌํ•œ ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๊ฐ€์ง€๋Š” ๋ถ€์žฌ๋Š” ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„์™€ ์œ ํšจ๋†’์ด์— ํฌ๊ฒŒ ์˜ํ–ฅ์„ ๋ฐ›๊ฒŒ ๋˜์–ด ๋ถ€์žฌ ์„ค๊ณ„ ์‹œ ์ด๋Ÿฌํ•œ ๋ณ€์ˆ˜์— ๋Œ€ํ•œ ๊ณ ๋ ค๊ฐ€ ํ•„์š”ํ•œ ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๊ธฐ์กด ํ‰๊ฐ€์‹๊ณผ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•œ ๊ฒฐ๊ณผ, ์ „๋‹จ ๊ฒฝ๊ฐ„๋น„์™€ ์œ ํšจ๋†’์ด๋ฅผ ๊ณ ๋ คํ•œ ์œ ๋กœ์ฝ”๋“œ ๊ธฐ๋ฐ˜์˜ ์‹์˜ ์˜ˆ์ธก๊ฐ’์ด ํŽธ์ฐจ๊ฐ€ ์ ์—ˆ๋‹ค.

4)๊ธฐ์กด ๊ฐ•๋„์‹์—์„œ๋Š” ์ „๋‹จ์ง€๊ฐ„๋น„์™€ ํฌ๊ธฐํšจ๊ณผ์— ๋Œ€ํ•œ ๋ณ€์ˆ˜๋Š” ํ•œ๊ณ„์ƒํƒœ์—์„œ์˜ ์ฃผ์ธ์žฅ๊ฐ๋„์— ๊ฐ„์ ‘์ ์œผ๋กœ ๋ฐ˜์˜๋˜์–ด ์žˆ์œผ๋‚˜, ์ฃผ์ธ์žฅ๊ฐ๋„์— ๋Œ€ํ•œ ์‹คํ—˜์ ์ธ ๊ทผ๊ฑฐ๋Š” ๋ถ€์กฑํ•˜์˜€๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ฃผ์ธ์žฅ๊ฐ๋„์— ๋Œ€ํ•œ ์‹คํ—˜์ž๋ฃŒ๋ฅผ ์ œ์‹œํ•˜์˜€์œผ๋ฉฐ ๋ชจ๋ธ๋ง ๊ธฐ๋ฐ˜ ํ‰๊ฐ€์‹์— ๋Œ€์ž…ํ•˜์˜€์„ ๋•Œ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ๋น„๊ต์  ์ •ํ™•ํžˆ ์˜ˆ์ธกํ•˜์˜€๋‹ค. ๋ณด๋‹ค ์ •๋ฐ€๋„๊ฐ€ ๋†’์€ ์ „๋‹จ๊ฐ•๋„ ์˜ˆ์ธก์„ ์œ„ํ•ด์„œ๋Š” ์žฌ๋ฃŒ ํ•œ๊ณ„๋ณ€ํ˜•์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ๋ณ‘ํ–‰๋˜์–ด์•ผ ํ•  ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค.

Acknowledgements

๋ณธ ์—ฐ๊ตฌ๋Š” ๊ตญํ† ๊ตํ†ต๋ถ€/๊ตญํ† ๊ตํ†ต๊ณผํ•™๊ธฐ์ˆ ์ง„ํฅ์› ๊ฑด์„ค๊ธฐ์ˆ ์—ฐ๊ตฌ์‚ฌ์—…(13๊ฑด์„ค์—ฐ๊ตฌA02)์˜ ์—ฐ๊ตฌ๋น„ ์ง€์›์— ์˜ํ•ด ์ˆ˜ํ–‰๋˜์—ˆ์Šต๋‹ˆ๋‹ค. ์ด์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

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