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์ „๋‹จ ๊ฐ•๋„, ๊ฐ•์„ฌ์œ , ํ•ฉ์„ฑ๋ณด, ๋ณตํ•ฉ ๊ณต๋ฒ•, ์ˆ˜ํ‰์ „๋‹จ
shear strength, steel fiber, composite beam, composite construction, horizontal shear

  • 1. ์„œ ๋ก 

  • 2. ์‹คํ—˜์ฒด ์„ค๊ณ„

  •   2.1 ํ˜„ํ–‰๊ธฐ์ค€์˜ ์ „๋‹จ๊ฐ•๋„

  •   2.2 ์‹คํ—˜ ๋ณ€์ˆ˜

  •   2.3 ์‹คํ—˜์ฒด ์„ค๊ณ„ ๋ฐ ์ œ์ž‘

  •   2.4 ์žฌ๋ฃŒ ๊ฐ•๋„

  • 3. ์‹คํ—˜ ๊ฒฐ๊ณผ

  •   3.1 ์‹คํ—˜์ฒด SU-A~SU-F

  •   3.2 ์‹คํ—˜์ฒด SR-A~SR-F

  • 4. ์‹คํ—˜๋ณ€์ˆ˜ ๋ถ„์„ ๋ฐ ํ˜„ํ–‰๊ธฐ์ค€๊ณผ์˜ ๋น„๊ต

  •   4.1 ์„ค๊ณ„๋ณ€์ˆ˜์˜ ์˜ํ–ฅ

  •   4.2 ์ „๋‹จ์ฒ ๊ทผ์˜ ์ „๋‹จ๊ฐ•๋„ ๊ธฐ์—ฌ๋„

  •   4.3 ์ˆ˜์ง์ „๋‹จ๊ฐ•๋„ ๊ธฐ์ค€์‹๊ณผ์˜ ๋น„๊ต

  •   4.4 ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„

  • 5. ๊ฒฐ ๋ก 

1. ์„œ    ๋ก 

์ตœ๊ทผ ๊ตญ๋‚ด ๊ฑด์„คํ˜„์žฅ์—์„œ๋Š” ๊ฑด์„ค ๋…ธ๋™์ž ์ธ๊ฑด๋น„ ์ƒ์Šน์— ๋”ฐ๋ผ ํ”„๋ฆฌ์บ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ(Precast Concrete, ์ดํ•˜ PC)์˜ ์‚ฌ์šฉ์ด ์ ์  ์ฆ๊ฐ€ํ•˜๋Š” ์ถ”์„ธ์ด๋‹ค. ํ•ด์™ธ ๊ฑด์ถ•ํ˜„์žฅ์—์„œ๋Š” ์ด๋ฏธ ๋งŽ์€ ๊ฑด๋ฌผ์— PC๊ณต๋ฒ•์ด ์‚ฌ์šฉ๋˜๊ณ  ์žˆ์ง€๋งŒ, ๊ตญ๋‚ด๊ฑด์ถ•ํ˜„์žฅ์—์„œ๋Š” ์ตœ๊ทผ ๋“ค์–ด ์ง€ํ•˜์ฃผ์ฐจ์žฅ์ด๋‚˜ ๋ฌผ๋ฅ˜์„ผํ„ฐ์™€ ๊ฐ™์€ ๋ชจ๋“ˆํ™”๋œ ๊ณ ํ•˜์ค‘ ์žฅ๊ฒฝ๊ฐ„ ๊ฑด๋ฌผ์„ ๋Œ€์ƒ์œผ๋กœ PC์™€ Cast-In-Place concrete (ํ˜„์žฅํƒ€์„ค ์ฝ˜ํฌ๋ฆฌํŠธ, ์ดํ•˜ CIP)๋ฅผ ํ•ฉ์„ฑํ•œ ๋ณตํ•ฉํ™” ๊ณต๋ฒ• ์‚ฌ์šฉ์ด ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ๋‹ค.

์•„ํŒŒํŠธ ์ง€ํ•˜ ์ฃผ์ฐจ์žฅ์ด๋‚˜ ๋Œ€ํ˜• ์ฐฝ๊ณ  ๊ฑด๋ฌผ์€ ๋งˆ๊ฐ์—†์ด ๊ตฌ์กฐ์ฒด๊ฐ€ ์™ธ๋ถ€์— ๋…ธ์ถœ๋˜๊ธฐ ๋•Œ๋ฌธ์— ์ฝ˜ํฌ๋ฆฌํŠธ ์ธ์žฅ๋ถ€์˜ ํœจ ๊ท ์—ด์ด ๋ฐœ์ƒํ•  ๊ฒฝ์šฐ ๋ˆ„์ˆ˜์™€ ์ฒ ๊ทผ ๋ถ€์‹ ๋ฌธ์ œ ๋“ฑ์ด ๋ฐœ์ƒํ•œ๋‹ค. ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ(Steel Fiber Reinforced Concrete, ์ดํ•˜ SFRC)๋ฅผ ์‚ฌ์šฉํ•  ๊ฒฝ์šฐ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ธ์žฅ๊ฐ•๋„๋ฅผ ์ฆ๊ฐ€์‹œ์ผœ ์‚ฌ์šฉ์„ฑ๊ณผ ๋‚ด๊ตฌ์„ฑ์„ ํ–ฅ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค. ํ˜„์žฅํƒ€์„ค ์ฝ˜ํฌ๋ฆฌํŠธ์—์„œ๋Š” ์‹œ๊ณต์„ฑ์˜ ๋ฌธ์ œ๋กœ SFRC ์‚ฌ์šฉ์ด ์–ด๋ ต์ง€๋งŒ, PC๊ณต์žฅ์ƒ์‚ฐ์—์„œ๋Š” ํƒ€์„ค์˜ ์–ด๋ ค์›€์—†์ด ์ ์šฉ๊ฐ€๋Šฅํ•˜๋‹ค.

SFRC๋Š” 1970๋…„๋Œ€๋ถ€ํ„ฐ ๋‹ค์–‘ํ•œ ์—ฐ๊ตฌ์ž๋“ค1-11)์— ์˜ํ•ด ์—ฐ๊ตฌ, ๊ฐœ๋ฐœ๋˜์—ˆ์ง€๋งŒ ํ˜„์žฅ ์ ์šฉ์—๋Š” ์ œํ•œ์ ์ด๋‹ค. ๋˜ํ•œ, ํ˜„ํ–‰ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๊ธฐ์ค€(KCI 201212), ACI318-1113))์—๋Š” ์ตœ์†Œ์ „๋‹จ์ฒ ๊ทผ ๋Œ€์šฉ์œผ๋กœ์˜ SFRC์— ๋Œ€ํ•œ ๊ธฐ์ค€๋งŒ ๊ทœ์ •๋˜์–ด ์žˆ๋‹ค. ์ฆ‰, โ€˜๋ณด์˜ ๊นŠ์ด๊ฐ€ 600 mm๋ฅผ ์ดˆ๊ณผํ•˜์ง€ ์•Š๊ณ  ์„ค๊ณ„๊ธฐ์ค€์••์ถ•๊ฐ•๋„๊ฐ€ 40 MPa์„ ์ดˆ๊ณผํ•˜์ง€ ์•Š๋Š” ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์— ์ž‘์šฉํ•˜๋Š” ๊ณ„์ˆ˜์ „๋‹จ๋ ฅ์ด /Resources/kci/JKCI.2015.27.5.501/images/PICEC76.gif๋ฅผ ์ดˆ๊ณผํ•˜์ง€ ์•Š๋Š” ๊ฒฝ์šฐโ€™ ์ตœ์†Œ ์ „๋‹จ์ฒ ๊ทผ์„ SFRC๋กœ ๋Œ€์ฒดํ•  ์ˆ˜ ์žˆ๋‹ค. ๋‹ค๋งŒ, ์ด๋•Œ SFRC์˜ ์ฒด์ ๋น„๋Š” 0.75%์ด์ƒ์ด์–ด์•ผ ํ•œ๋‹ค.

๋ณตํ•ฉํ™” ๊ณต๋ฒ•์—์„œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํ•ฉ์„ฑ๋‹จ๋ฉด์€ ์„œ๋กœ ๋‹ค๋ฅธ ์žฌ๋ฃŒ์ ์ธ ํŠน์„ฑ์„ ๊ฐ€์ง€๊ธฐ ๋•Œ๋ฌธ์— ํ˜„ํ–‰ ๊ตฌ์กฐ ๊ธฐ์ค€(KCI 2012 17.2.(3), ACI318-11 17.2.3)์— ๋”ฐ๋ผ ์ „๋‹จ๊ฐ•๋„ ์‚ฐ์ •์‹œ ๊ฐ ์š”์†Œ์˜ ํŠน์„ฑ์„ ๋”ํ•ด์„œ ์‚ฌ์šฉํ•˜๊ฑฐ๋‚˜ ์ด๋“ค ์ค‘ ๊ฐ€์žฅ ๋ถˆ๋ฆฌํ•œ ๊ฐ’์„ ์‚ฌ์šฉํ•˜์—ฌ ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ๊ฐ•๋„๋ฅผ ์‚ฐ์ •ํ•˜์—ฌ์•ผ ํ•œ๋‹ค. ํ•˜์ง€๋งŒ ์ด๋Ÿฌํ•œ ์ „๋‹จ๊ฐ•๋„ ์‚ฐ์ •๋ฒ•์— ๋Œ€ํ•œ ๋ช…ํ™•ํ•œ ๊ฒ€์ฆ์ด ์—†๋Š” ์ƒํƒœ15-17)์ด๊ณ , ๊ฐ€์žฅ ๋ถˆ๋ฆฌํ•œ ๊ฐ’์„ ์‚ฌ์šฉํ•  ๊ฒฝ์šฐ ๊ฒฝ์ œ์ ์ธ ์„ค๊ณ„๊ฐ€ ์–ด๋ ต๋‹ค. ๋˜ํ•œ, SFRC๋Š” ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ๊ณจ์žฌ์˜ ๊ฑฐ์นœ๋ฉด ํ˜•์„ฑ์ด ์–ด๋ ต๊ธฐ ๋•Œ๋ฌธ์— ๊ณ„๋ฉด ๋งˆ์ฐฐ๋ ฅ์ด ๋–จ์–ด์ง„๋‹ค. ๋”ฐ๋ผ์„œ 6 mm ๊ฑฐ์นœ ๊ณ„๋ฉด์— ์ ์šฉํ•˜๊ณ  ์žˆ๋Š” ํ˜„ํ–‰ ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„ ์‹(์‹ (4)์™€ (5))์„ SFRC ํ•ฉ์„ฑ๋‹จ๋ฉด์— ์‚ฌ์šฉ๊ฐ€๋Šฅํ•œ์ง€ ํ™•์ธ์ด ํ•„์š”ํ•˜๋‹ค.

ํ•ฉ์„ฑ๋‹จ๋ฉด์— ๊ด€ํ•œ ๊ธฐ์กด์—ฐ๊ตฌ15-17)๋Š” ๊ฐ•๋„๊ฐ€ ์„œ๋กœ ๋‹ค๋ฅธ ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ์‚ฌ์šฉํ•œ ํ•ฉ์„ฑ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„์— ๋Œ€ํ•ด ์ค‘์ ์ ์œผ๋กœ ํ‰๊ฐ€์˜€๋‹ค๋ฉด, ๋ณธ ์—ฐ๊ตฌ๋Š” SFRC์™€ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ ํ•ฉ์„ฑ๋‹จ๋ฉด์ ๋น„๋ฅผ ์ฃผ์š” ๋ณ€์ˆ˜๋กœ PC๋กœ ์ œ์ž‘์ด ์šฉ์ดํ•œ SFRC๊ฐ€ ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ์ „๋‹จ๊ฐ•๋„์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๋ถ„์„ํ•˜์˜€๋‹ค.

2. ์‹คํ—˜์ฒด ์„ค๊ณ„

2.1 ํ˜„ํ–‰๊ธฐ์ค€์˜ ์ „๋‹จ๊ฐ•๋„

์ฝ˜ํฌ๋ฆฌํŠธ ํœจ ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„์— ๋Œ€ํ•œ ํ˜„ํ–‰๊ตฌ์กฐ๊ธฐ์ค€12,13)์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค. KCI201212)(ACI318-1113))์—์„œ ๊ณต์นญ ์ˆ˜์ง ์ „๋‹จ ๊ฐ•๋„๋Š” ๋‹ค์Œ ๋‘ ๊ฐœ์˜ ์‹์„ ์‚ฌ์šฉํ•  ์ˆ˜ ์žˆ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/PICEDFD.gif (1)

๋˜๋Š” /Resources/kci/JKCI.2015.27.5.501/images/PICEE6C.gif        (2)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2015.27.5.501/images/PICEE9B.gif์ด๊ณ  /Resources/kci/JKCI.2015.27.5.501/images/PICEEDB.gif์ด๊ณ  /Resources/kci/JKCI.2015.27.5.501/images/PICEEEC.gif๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์„ค๊ณ„๊ธฐ์ค€ ์••์ถ•๊ฐ•๋„, /Resources/kci/JKCI.2015.27.5.501/images/PICEEFC.gif๋Š” ๋ณต๋ถ€์˜ ํญ, /Resources/kci/JKCI.2015.27.5.501/images/PICEF1C.gif๋Š” ์ข…๋ฐฉํ–ฅ ์ธ์žฅ์ฒ ๊ทผ์˜ ์ค‘์‹ฌ์—์„œ ์••์ถ•์ฝ˜ํฐ๋ฆฌํŠธ ์—ฐ๋‹จ๊นŒ์ง€ ๊ฑฐ๋ฆฌ, /Resources/kci/JKCI.2015.27.5.501/images/PICEF2D.gif, /Resources/kci/JKCI.2015.27.5.501/images/PICEF3E.gif๋Š” ๋‹จ๋ฉด์—์„œ์˜ ๊ณ„์ˆ˜์ „๋‹จ๋ ฅ, /Resources/kci/JKCI.2015.27.5.501/images/PICEF6E.gif๋Š” ๊ณ„์ˆ˜ ํœจ๋ชจ๋ฉ˜ํŠธ๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.

ACI54414)์—์„œ ๊ฐ•์„ฌ์œ ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ „๋‹จ๊ฐ•๋„ ์‹์€ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ •์˜ํ•œ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/PICEF7E.gif (3)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2015.27.5.501/images/PICEF8F.gif์€ ์ชผ๊ฐฌ ์ธ์žฅ์‹คํ—˜์—์„œ ๊ตฌํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ์ธ์žฅ๊ฐ•๋„์ด๊ณ , /Resources/kci/JKCI.2015.27.5.501/images/PICEFAF.gif๋Š” ์œ ํšจ๊นŠ์ด์™€ ์ „๋‹จ๊ฒฝ๊ฐ„์˜ ๋น„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ์ธ์žฅ๊ฐ•๋„(/Resources/kci/JKCI.2015.27.5.501/images/PICEFC0.gif)๋Š” ๊ฐ•์„ฌ์œ ์˜ ์ข…๋ฅ˜์™€ ์–‘์— ์˜ํ–ฅ์„ ๋ฐ›์œผ๋ฉฐ, ACI318-1113)์— ๋”ฐ๋ฅด๋ฉด /Resources/kci/JKCI.2015.27.5.501/images/PICEFE0.gif์œผ๋กœ ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ๋‹ค.

์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„์— ๋Œ€ํ•ด์„œ ์ตœ์†Œ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์—†๊ณ  ์ ‘์ด‰๋ฉด์ด ์ฒญ๊ฒฐํ•˜๊ณ  ๋ถ€์œ ๋ฌผ์ด ์—†์œผ๋ฉฐ ํ‘œ๋ฉด์„ ๊ฑฐ์น ๊ฒŒ ๋งŒ๋“ค์–ด์ง„ ๊ฒฝ์šฐ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ •์˜ํ•œ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/PICEFF1.gif (4)

์ตœ์†Œ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์žˆ๊ณ , ํ‘œ๋ฉด์ด ์•ฝ 6 mm ๊นŠ์ด๋กœ ๊ฑฐ์น ๊ฒŒ ๋งŒ๋“ค์–ด์ง„ ๊ฒฝ์šฐ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ •์˜ํ•œ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/PICF05F.gif (5)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2015.27.5.501/images/PICF07F.gif๋Š” ์ ‘์ด‰ ๋ฉด์ ์— ๋Œ€ํ•œ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ ๋ฉด์ ์˜ ๋น„, /Resources/kci/JKCI.2015.27.5.501/images/PICF090.gif๋Š” ์ˆ˜ํ‰์ „๋‹จ์— ๋Œ€ํ•˜์—ฌ ๊ฒ€ํ† ๋˜๋Š” ์ ‘์ด‰ ๋ฉด์ ์˜ ๋‹จ๋ฉด ํญ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์ตœ์†Œ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๋Š” ์‹(6)์— ๋”ฐ๋ผ ์‚ฐ์ •ํ•˜์—ฌ์•ผ ํ•˜๊ณ  ์—ฐ๊ฒฐ์žฌ์˜ ๊ฐ„๊ฒฉ์€ ์ง€์ง€์š”์†Œ์˜ ์ตœ์†Œ ์น˜์ˆ˜์˜ 4๋ฐฐ, ๋˜ํ•œ 600 mm ์ดํ•˜์ด์–ด์•ผ ํ•œ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/PICF0CF.gif (6)

2.2 ์‹คํ—˜ ๋ณ€์ˆ˜

๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ๊ณ ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ์ผ๋ฐ˜ ๋ณดํ†ต ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ๋กœ ๋ถ„๋ฆฌํƒ€์„ค ๋œ ํ•ฉ์„ฑ ํœจ ๋ถ€์žฌ์˜ ์ „๋‹จ ์„ฑ๋Šฅ ํ‰๊ฐ€๋ฅผ ์œ„ํ•ด ๊ณ ๊ฐ•๋„์™€ ๋ณดํ†ต ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๋‹จ๋ฉด์ ๋น„์™€ ์ „๋‹จ์ฒ ๊ทผ๋น„๋ฅผ ๋ณ€์ˆ˜๋กœ ๋‹จ์ˆœ์ง€์ง€ ๋ณด ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ๋‹จ๋ฉด์ ๋น„๋Š” Fig. 1(c)์™€ ๊ฐ™์ด ์ด 6๊ฐ€์ง€๋กœ ๊ตฌ์„ฑํ•˜์˜€๋‹ค. ๋‹จ๋ฉด A์™€ B๋Š” ๊ฐ๊ฐ 24 MPa ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์™€ 60 MPa ๊ณ ๊ฐ•๋„ ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ์ „๋‹จ๋ฉด์— ํƒ€์„คํ•œ ๋‹จ๋ฉด์œผ๋กœ, ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ํ•ฉ์„ฑ๋‹จ๋ฉด C~F์™€์˜ ๋น„๊ต๋ฅผ ์œ„ํ•œ ์‹คํ—˜์ฒด์ด๋‹ค. ํ•ฉ์„ฑ๋‹จ๋ฉด C์™€ D๋Š” ๋ณดํ†ต๊ฐ•๋„ ํ˜„์žฅํƒ€์„ค ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊นŠ์ด๊ฐ€ ์ „๋‹จ๊ฐ•๋„์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•œ ๋‹จ๋ฉด์œผ๋กœ, ๋‹จ๋ฉด C์˜ ์ƒ๋ถ€ 3/8๊ณผ ๋‹จ๋ฉด D์˜ ์ƒ๋ถ€ 5/8์— ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ(24 MPa)๋ฅผ ํƒ€์„คํ•˜์˜€๋‹ค. ํ•ฉ์„ฑ๋‹จ๋ฉด E์™€ F๋Š” ์—ฐ์†๋ณด ๋‹จ๋ถ€์˜ ๋ถ€๋ชจ๋ฉ˜ํŠธ ์ž‘์šฉ ๋‹จ๋ฉด์—์„œ ์••์ถ•๋Œ€์˜ ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ๊นŠ์ด๊ฐ€ ์ „๋‹จ๊ฐ•๋„์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•œ ๋‹จ๋ฉด์œผ๋กœ ๋‹จ๋ฉด E์˜ ์ƒ๋ถ€ 3/8๊ณผ ๋‹จ๋ฉด F์˜ ์ƒ๋ถ€ 5/8์— ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ(60 MPa)๋ฅผ ํƒ€์„คํ•˜์˜€๋‹ค. ์—ฌ๊ธฐ์„œ, 60 MPa ๊ณ ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ์‚ฌ์šฉํ•œ ์ด์œ ๋Š” PC์™€ CIP๋ถ€์žฌ๊ฐ„์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„ ์ฐจ์ด๋ฅผ ํฌ๊ฒŒ ํ•˜์—ฌ ๋ช…ํ™•ํ•œ ๊ฒฐ๊ณผ๋ฅผ ์–ป๊ธฐ ์œ„ํ•จ์ด๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F1.jpg

Fig. 1 Reinforcement arrangement and cross sections

๋‘๋ฒˆ์งธ๋กœ ์ „๋‹จ์ฒ ๊ทผ๋น„๋ฅผ ๋ณ€์ˆ˜๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค. SU ์‹คํ—˜์ฒด๋Š” ์ „๋‹จ์ฒ ๊ทผ์ด ์—†๋Š” ์‹คํ—˜์ฒด์ด๊ณ  SR ์‹คํ—˜์ฒด๋Š” ์ตœ์†Œ ์ „๋‹จ์ฒ ๊ทผ(์‹ (6))์ด ๋ณด๊ฐ•๋œ ์‹คํ—˜์ฒด๋กœ ์ „๋‹จ์ฒ ๊ทผ D10์„ 450 mm ๊ฐ„๊ฒฉ์œผ๋กœ ๋ฐฐ์น˜ํ•˜์—ฌ ์ตœ์†Œ ์ „๋‹จ์ฒ ๊ทผ์ด ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์˜ ์ˆ˜ํ‰์ „๋‹จ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์—ฐ๊ตฌํ•˜์˜€๋‹ค. ์ „๋‹จ์ฒ ๊ทผ์€ ์ˆ˜์ง์ „๋‹จ์— ์ €ํ•ญํ•˜๊ธฐ ์œ„ํ•œ ์ตœ๋Œ€ ์ „๋‹จ์ฒ ๊ทผ ๊ฐ„๊ฒฉ(d/2=170 mm)๋ณด๋‹ค 2๋ฐฐ ์ด์ƒ ๋„“๊ฒŒ ๋ฐฐ์น˜ํ•˜์—ฌ ์ „๋‹จ์ฒ ๊ทผ์ด ์ˆ˜์ง์ „๋‹จ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์ตœ์†Œํ™”ํ•˜์˜€๋‹ค.

2.3 ์‹คํ—˜์ฒด ์„ค๊ณ„ ๋ฐ ์ œ์ž‘

๋ชจ๋“  ์‹คํ—˜์ฒด์˜ ๋‹จ๋ฉดํฌ๊ธฐ๋Š” 260 mm ร— 400 mm์ด๋ฉฐ, ์ง€์ ๊ฐ„ ์ด ๊ธธ์ด๋Š” 3,120 mm์ด๋‹ค. ํœจ ์ฒ ๊ทผ์˜ ์ •์ฐฉ์„ ์œ„ํ•ด ์ง€์ ์—์„œ๋ถ€ํ„ฐ 450 mm ์—ฐ์žฅ์‹œ์ผฐ๊ณ  ํœจ ์ฒ ๊ทผ์€ SD500 D25๋ฅผ 1๋‹จ์œผ๋กœ 3๊ฐ€๋‹ฅ ๋ฐฐ์น˜ํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF0E0.gif=1.72%). ์ „๋‹จ์ฒ ๊ทผ ๊ฐ„๊ฒฉ์€ ์ตœ์†Œ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ ๊ธฐ์ค€(์‹ (6))์— ๋งŒ์กฑํ•˜๊ณ  ์ทจ์„ฑ์  ํŒŒ๊ดด๋ฅผ ๋ณด์ด๋Š” ๊ณ ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ๊ธฐ์ค€์œผ๋กœ ๊ณ„์‚ฐํ•˜์˜€๋‹ค. ์ „๋‹จ์ฒ ๊ทผ ์ •์ฐฉ์„ ์œ„ํ•ด ์ƒ๋ถ€์— SD400 D13์„ ๋ฐฐ์น˜ํ•˜์˜€๋‹ค. ๊ฐ•์„ฌ์œ ๋Š” ์ฝ”์Šคํ‹ธ(Kosteel)์—์„œ ์ œ์ž‘ํ•˜๋Š” ๋ฒˆ๋“œ๋ ‰์Šค(Bundrex) ์ œํ’ˆ์œผ๋กœ ํ˜•์ƒ๋น„(/Resources/kci/JKCI.2015.27.5.501/images/PICF100.gif=30/0.5)๋Š” 60์ด๊ณ  ์ธ์žฅ๊ฐ•๋„๋Š” 1,336 MPa์ด๋‹ค. ๊ฐ•์„ฌ์œ  ์ฒด์ ๋น„๋Š” ํ˜„ํ–‰ ACI318-1113)์—์„œ ์ œ์‹œํ•˜๋Š” ์ตœ์†Œ ์ฒด์ ๋น„์ธ 0.75%๋ฅผ ์ ์šฉํ•˜์˜€๋‹ค. ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ์ œ์ž‘์‹œ ๊ฐ•์„ฌ์œ ์˜ ๋ญ‰์นจ ํ˜„์ƒ์„ ์ตœ์†Œํ™”ํ•˜๊ธฐ ์œ„ํ•ด ๊ฐ•์„ฌ์œ ๋ฅผ ์ฒœ์ฒœํžˆ ํ˜ผ์ž…ํ•˜์˜€๊ณ , ์œ ๋™์„ฑ ํ™•๋ณด๋ฅผ ์œ„ํ•ด ๊ณ ์„ฑ๋Šฅ ๊ฐ์ˆ˜์ œ(MEGAD 601PC)๋ฅผ ์‹œ๋ฉ˜ํŠธ ์ค‘๋Ÿ‰์˜ 1.3% ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ด์™€ ๊ฐ™์€ ์‹œ๊ณต๋ฐฉ๋ฒ•๊ณผ ๊ณ ์„ฑ๋Šฅ ๊ฐ์ˆ˜์ œ์˜ ์‚ฌ์šฉ์œผ๋กœ ์‹คํ—˜์ฒด ์ œ์ž‘์˜ ์‹œ๊ณต์„ฑ์„ ํ™•๋ณดํ•  ์ˆ˜ ์žˆ์—ˆ๋‹ค.

Table 1์€ 12๊ฐœ ์‹คํ—˜์ฒด๋“ค์˜ ์˜ˆ์ธก ํœจ ๊ฐ•๋„์™€ ์˜ˆ์ธก ์ˆ˜์ง ๋ฐ ์ˆ˜ํ‰ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋ชจ๋“  ์‹คํ—˜์ฒด๋Š” ํœจ ์„ฑ๋Šฅ(/Resources/kci/JKCI.2015.27.5.501/images/PICF111.gif)์— ๋„๋‹ฌํ•˜๊ธฐ ์œ„ํ•œ ํœจ ์š”๊ตฌ์ „๋‹จ๋ ฅ(/Resources/kci/JKCI.2015.27.5.501/images/PICF131.gif)์„ ์ˆ˜์ง ์ „๋‹จ์„ฑ๋Šฅ(/Resources/kci/JKCI.2015.27.5.501/images/PICF151.gif)๋ณด๋‹ค ํฌ๊ฒŒ ์„ค๊ณ„ํ•˜์—ฌ ํœจ ํ•ญ๋ณต ์ „์— ์ „๋‹จํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜๋„๋ก ๊ณ„ํšํ•˜์˜€๋‹ค. ์—ฌ๊ธฐ์„œ, ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ „๋‹จ๊ฐ•๋„ ์‹์€ ํ˜„ํ–‰ ๊ธฐ์ค€12,13)์— ์ œ์‹œ๋˜์–ด ์žˆ์ง€ ์•Š๊ธฐ ๋•Œ๋ฌธ์— ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„์‹(์‹ (1))์„ ์‚ฌ์šฉํ•˜์˜€๊ณ  ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ์ˆ˜์ง์ „๋‹จ์„ฑ๋Šฅ์€ ๊ฐ ์š”์†Œ๋ณ„๋กœ ๊ณ„์‚ฐํ•œ ํ›„ ํ•ฉ์‚ฐํ•˜์˜€๋‹ค. ์ „๋‹จ์ฒ ๊ทผ ๊ฐ„๊ฒฉ(450 mm)์€ ์ˆ˜์ง์ „๋‹จ์— ์ €ํ•ญํ•˜๊ธฐ ์œ„ํ•œ ์ตœ๋Œ€ ๊ฐ„๊ฒฉ d/2(170 mm)๋ฅผ ๋„˜๊ธฐ ๋•Œ๋ฌธ์— ์ „๋‹จ์ฒ ๊ทผ์— ์˜ํ•œ ์ „๋‹จ๊ฐ•๋„๋Š” ๋ฌด์‹œํ•˜์˜€๋‹ค.

๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์—์„œ์˜ ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„ ๊ฒ€ํ† ๋ฅผ ์œ„ํ•ด ๊ณต์นญ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„(/Resources/kci/JKCI.2015.27.5.501/images/PICF152.gif, ์‹ (4)์™€ (5))์™€ ์ˆ˜ํ‰์ „๋‹จ๋ ฅ(/Resources/kci/JKCI.2015.27.5.501/images/PICF182.gif)์„ ๋น„๊ตํ•˜์˜€๋‹ค. ์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2015.27.5.501/images/PICF1B2.gif๋Š” ๊ณต์นญ ์ˆ˜์ง ์ „๋‹จ๊ฐ•๋„(/Resources/kci/JKCI.2015.27.5.501/images/PICF1B3.gif)์— ์ƒ์‘ํ•˜๋Š” ํ•˜์ค‘ ๋ฐœ์ƒ์‹œ ๊ณ„๋ฉด์— ์ž‘์šฉํ•˜๋Š” ์ˆ˜ํ‰์ „๋‹จ๋ ฅ์œผ๋กœ Fig. 2์™€ ๊ฐ™์ด ๋‘ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฒฝ๊ณ„๋ฉด์—์„œ์˜ ์••์ถ•๋ ฅ์ด๋‚˜ ์ธ์žฅ๋ ฅ์˜ ๋ณ€ํ™”๋Ÿ‰์œผ๋กœ ์‚ฐ์ •ํ•˜์˜€๋‹ค. ์ „๋‹จ์ฒ ๊ทผ์ด ์—†๋Š” ์‹คํ—˜์ฒด์˜ /Resources/kci/JKCI.2015.27.5.501/images/PICF1D3.gif๋Š” 1.87~2.32๋กœ ๋ชจ๋“  ํ•ฉ์„ฑ๋‹จ๋ฉด ์‹คํ—˜์ฒด๋Š” ์ˆ˜์ง์ „๋‹จํŒŒ๊ดด ์ด์ „์— ์ˆ˜ํ‰์ „๋‹จํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•  ๊ฒƒ์œผ๋กœ ์˜ˆ์ƒ๋˜์—ˆ๊ณ  ์ตœ์†Œ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์žˆ๋Š” ์‹คํ—˜์ฒด์˜ /Resources/kci/JKCI.2015.27.5.501/images/PICF213.gif๋Š” 0.50~0.62๋กœ ์ˆ˜์ง์ „๋‹จํŒŒ๊ดด๊ฐ€ ์˜ˆ์ƒ๋˜์—ˆ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F2.jpg

Fig. 2 Horizontal shear force at the interface of composite beams

์‹คํ—˜์ฒด ์ œ์ž‘์€ ๋‘ ์ฐจ๋ก€์— ๊ฑธ์ณ ์ง„ํ–‰๋˜์—ˆ๋‹ค. ํœจ์ฒ ๊ทผ๊ณผ ์ „๋‹จ์ฒ ๊ทผ์— ์ฒ ๊ทผ์šฉ ๋ณ€ํ˜•๋ฅ  ๊ฒŒ์ด์ง€(Strain guage)๋ฅผ ๋ถ€์ฐฉ์‹œํ‚จ ํ›„ 60 MPa SFRC๋ฅผ 1์ฐจ ํƒ€์„คํ•˜๊ณ  ์ฆ๊ธฐ ์–‘์ƒํ•˜์˜€๋‹ค. ๋‹จ๋ฉด E์™€ F๋Š” ํœจ ์ฒ ๊ทผ์„ ๋’ค์ง‘์€ ์ƒํƒœ๋กœ ํƒ€์„คํ•˜์˜€๋‹ค. ๋ถ„๋ฆฌ ํƒ€์„คํ•  ๊ณ„๋ฉด์˜ ๋งˆ์ฐฐ๋ ฅ์„ ๋†’์ด๊ธฐ ์œ„ํ•ด ํ˜„ํ–‰ ๊ธฐ์ค€์— ๋”ฐ๋ผ ๋ ˆ์ดํ„ด์Šค(laitance)๋ฅผ ์ œ๊ฑฐํ•˜๊ณ  ์ง€์—ฐ์ œ์™€ ์ˆ˜์••์„ ํ™œ์šฉํ•˜์—ฌ ํ‘œ๋ฉด์„ 6 mm์ด์ƒ ๊ฑฐ์น ๊ฒŒ ์ฒ˜๋ฆฌํ•˜์˜€์ง€๋งŒ ํ‘œ๋ฉด์— ํฉ์–ด์ ธ ์žˆ๋Š” ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ๊ณจ์žฌ์˜ ๊ฑฐ์นœ๋ฉด ํ˜•์„ฑ์ด ์ž˜ ์ด๋ค„์ง€์ง€ ์•Š์•˜๋‹ค. SFRC๊ฐ€ ์–‘์ƒ์ด ์ด๋ค„์ง„ ์ดํ›„ 24 MPa ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ 2์ฐจ๋กœ ํƒ€์„คํ•˜์˜€๋‹ค. ์••์ถ• ๋ฐ ์ธ์žฅ๊ฐ•๋„ ์‹œํ—˜์šฉ ๊ณต์‹œ์ฒด๋Š” ์‹คํ—˜์ฒด์™€ ๊ฐ™์€ ์กฐ๊ฑด์—์„œ ํƒ€์„ค, ์–‘์ƒํ•˜์˜€๋‹ค.

Table 1 Test variables and predictions of moment and shear capacities of specimens

Specimens

Section

type

Longitudinal reinforcement (ratio)

Shear re-bar

(ratio)

a/d

/Resources/kci/JKCI.2015.27.5.501/images/PIC6F67.gif

(kNยทm)

/Resources/kci/JKCI.2015.27.5.501/images/PIC6F88.gif

(kN)

/Resources/kci/JKCI.2015.27.5.501/images/PIC6F89.gif

(kN)

/Resources/kci/JKCI.2015.27.5.501/images/PIC6FC8.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC6FE8.gif

(kN)

/Resources/kci/JKCI.2015.27.5.501/images/PIC6FF9.gif1)

(kN)

/Resources/kci/JKCI.2015.27.5.501/images/PIC7019.gif

SU-A

A

SD500

-3D25

(1.72%)

Non

4.0

218

161

72

2.22

-

-

-

SU-B

B

258

190

114

1.66

-

-

-

SU-C

C

218

161

96

1.68

198

426

2.15

SU-D

D

218

161

83

1.92

198

371

1.87

SU-E

E

258

190

91

2.09

198

404

2.04

SU-F

F

258

190

103

1.84

198

459

2.32

SR-A

A

SD400-D10

(0.12%)

218

161

72

2.22

-

-

-

SR-B

B

258

190

114

1.66

-

-

-

SR-C

C

218

161

96

1.68

739

426

0.58

SR-D

D

218

161

83

1.92

739

371

0.5

SR-E

E

258

190

91

2.09

739

404

0.55

SR-F

F

258

190

103

1.84

739

459

0.62

1) /Resources/kci/JKCI.2015.27.5.501/images/PIC70C6.gif, /Resources/kci/JKCI.2015.27.5.501/images/PIC70E6.gif= Shear span, /Resources/kci/JKCI.2015.27.5.501/images/PIC70F7.gif=Distance from extreme compression fiber to centroid of tension reinforcement

2.4 ์žฌ๋ฃŒ ๊ฐ•๋„

์‹คํ—˜์ฒด์—๋Š” ๊ณต์นญ๊ฐ•๋„ 24 MPa์™€ 60 MPa ๋‘ ๊ฐ€์ง€ ์ข…๋ฅ˜์˜ ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, Table 2๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๋ฐฐํ•ฉ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ์›์ฃผ๊ณต์‹œ์ฒด๋Š” KS F 2403 ๊ธฐ์ค€์„ ๋”ฐ๋ผ 100 mm ร— 200 mm๋กœ ์ œ์ž‘ํ•˜์˜€๊ณ  ๊ณต์‹œ์ฒด๋ฅผ ๊ฐ•๋„๋ณ„๋กœ 3๊ฐœ์”ฉ KS F 2405 ๊ธฐ์ค€์„ ๋”ฐ๋ผ ์••์ถ• ๊ฐ•๋„ ์‹œํ—˜๊ณผ KS F 2423 ๊ธฐ์ค€์„ ๋”ฐ๋ผ ์ชผ๊ฐฌ ์ธ์žฅ ๊ฐ•๋„ ์‹œํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์‹œํ—˜๊ฒฐ๊ณผ๋Š” Fig. 3๊ณผ Table 4์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. Fig. 3์˜ ์ชผ๊ฐฌ ์ธ์žฅ๊ฐ•๋„ ์‹œํ—˜๊ฒฐ๊ณผ๋ฅผ ์‚ดํŽด๋ณด๋ฉด, ๊ฐ•์„ฌ์œ ๊ฐ€ ์‚ฌ์šฉ๋œ SU ๊ณต์‹œ์ฒด์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ์‚ฌ์šฉ๋˜์ง€ ์•Š์€ 60 MPa ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ๋น„์Šทํ•˜์˜€์ง€๋งŒ, SR ๊ณต์‹œ์ฒด๋Š” 40%์ด์ƒ ์ธ์žฅ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ด๋Š” SU์™€ SR ๊ณต์‹œ์ฒด๊ฐ€ ๋น„๋ก ๊ฐ™์€ ๋ฐฐํ•ฉ์œผ๋กœ ์ œ์ž‘๋˜์—ˆ์ง€๋งŒ ๋‹ค๋ฅธ ๋‚  ํƒ€์„ค๋˜์—ˆ๊ธฐ ๋•Œ๋ฌธ์— ์–‘์ƒ์กฐ๊ฑด ๋ฐ ๊ฐ•์„ฌ์œ ์˜ ๋ถ„์‚ฐ๋„ ์ฐจ์ด๋ฅผ ๋ณด์˜€๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ๋˜ํ•œ, ๋ณธ ์‹คํ—˜์— ์‚ฌ์šฉ๋œ ๊ฐ•์„ฌ์œ ๋Š” ์ธ์žฅ๊ฐ•๋„๋ณด๋‹ค๋Š” ๋ณ€ํ˜•๋Šฅ๋ ฅ ์ฆ๊ฐ€์— ํฌ๊ฒŒ ๊ธฐ์—ฌํ•˜์˜€๋‹ค. SU์™€ SR ๊ณต์‹œ์ฒด์˜ ๊ฒฝ์šฐ ์ชผ๊ฐฌ ์ธ์žฅ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์ดํ›„ ๊ท ์—ด๋ฉด ์‚ฌ์ด์˜ ๊ฐ•์„ฌ์œ ๊ฐ€ ์ธ์žฅ๋ ฅ์„ ์ „๋‹ฌํ•˜๋ฉด์„œ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ๋ณด๋‹ค ๋ณ€ํ˜• ๋Šฅ๋ ฅ์ด ํฌ๊ฒŒ ํ–ฅ์ƒ๋˜์—ˆ๋‹ค.

Table 2 Mixture proportions of concrete

Nominal strength

W/C (%)

Unit weight (kg/m3)

W

C

S

G

SP

24

49.4

162

328

869

979

3.5

60

29

180

620

625

935

8.06

*Maximum aggregate size=25 mm

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F3.jpg

Fig. 3 Splitting tensile strength of concrete

์ฒ ๊ทผ์€ SD400 D10, SD400 D13, ๊ทธ๋ฆฌ๊ณ  SD500 D25๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ฒ ๊ทผ์˜ ๊ธฐ๊ณ„์  ์„ฑ์งˆ์„ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•ด KS B 0801์˜ ๊ธˆ์†์žฌ๋ฃŒ ์ธ์žฅ์‹œํ—˜ ๊ทœ์ •์— ๋”ฐ๋ผ ์‹œํ—˜ํŽธ์„ ์ œ์ž‘ํ•˜์˜€๊ณ  KS B 0802์— ๋”ฐ๋ผ ์‹œํ—˜์„ ์‹ค์‹œํ•˜์˜€๋‹ค. ์‚ฌ์šฉํ•œ ์ฒ ๊ทผ์˜ ๊ธฐ๊ณ„์  ํŠน์„ฑ์€ Table 3์— ๋‚˜ํƒ€๋ƒˆ๋‹ค.

Table 3 Mechanical properties of reinforcement

Type

/Resources/kci/JKCI.2015.27.5.501/images/PIC3468.gif(MPa)

/Resources/kci/JKCI.2015.27.5.501/images/PIC3488.gif(ฮผฮต)

/Resources/kci/JKCI.2015.27.5.501/images/PIC34A9.gif(GPa)

SD400 D10

467

2,382

196

SD400 D13

480

2,400

200

SD500 D25

555

2,968

187

3. ์‹คํ—˜ ๊ฒฐ๊ณผ

3.1 ์‹คํ—˜์ฒด SU-A~SU-F

์‹คํ—˜์ฒด SU-A~SU-F๋Š” ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์‚ฌ์šฉ๋˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด๋กœ ๊ทธ ๊ฒฐ๊ณผ๋Š” Fig. 4, 5์™€ Table 4์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์‹คํ—˜ ๊ฐ•๋„๋Š” โ€˜SU-B (408 kN) > SU-C (272 kN) > SU-D (228 kN) > SU-A (155 kN) > SU-E โ‰ƒ SU-F (150 kN)โ€™์ˆœ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. SFRC๊ฐ€ ์ธ์žฅ๋Œ€์— ์‚ฌ์šฉ๋œ ๋‹จ๋ฉด B~D๋Š” SFRC๊ฐ€ ์••์ถ•๋Œ€์— ์‚ฌ์šฉ๋œ ๋‹จ๋ฉด E์™€ F์— ๋น„ํ•ด ํฐ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋ณด์˜€๊ณ , ์ธ์žฅ๋Œ€๊ฐ€ 24MPa์ธ ๋‹จ๋ฉด A, E, F๋Š” ์ดˆ๊ธฐ ์‚ฌ์ธ์žฅ(์ˆ˜ํ‰) ๊ท ์—ด ๊ฐ•๋„๊ฐ€ ๋น„์Šทํ•˜์˜€๋‹ค. ๋‹จ๋ฉด E์™€ F๋Š” ๋‹จ๋ฉด A์™€ ๋น„์Šทํ•œ ์ดˆ๊ธฐ ํœจ ๊ท ์—ด์–‘์ƒ์„ ๋ณด์˜€๊ณ , ํœจ ๊ท ์—ด์ด ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์— ๋„๋‹ฌํ•˜๋Š” ์ˆœ๊ฐ„ ์ˆ˜ํ‰๊ท ์—ด ๋ฐœ์ƒ๊ณผ ํ•จ๊ป˜ ํ•˜์ค‘์ด ๊ธ‰๊ฒฉํžˆ ๊ฐ์†Œํ•˜์˜€๋‹ค.

ํœจ ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•๋ฅ ์„ ์‚ดํŽด๋ณด๋ฉด, SU-B์—์„œ๋งŒ ํœจ ์ฒ ๊ทผ์ด ํ•ญ๋ณต๋ณ€ํ˜•๋ฅ ์— ๋„๋‹ฌํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF252.gif). SU-B์˜ ํœจ ์ฒ ๊ทผ์€ ํ•ญ๋ณตํ•˜์˜€์ง€๋งŒ, ํ•˜์ค‘์ด ์‚ฌ์ธ์žฅ ๊ท ์—ด์— ์ง‘์ค‘๋˜๋ฉด์„œ ์ตœ์ข…์ ์œผ๋กœ ์ „๋‹จํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค.

Fig. 5๋Š” ์ตœ์ข…ํŒŒ๊ดด ๊ท ์—ด ์–‘์ƒ์„ ๋‚˜ํƒ€๋‚ด๋Š” ๊ฒƒ์œผ๋กœ ๋‹จ์ผ๋‹จ๋ฉด A์™€ B๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด์— ์˜ํ•ด ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ, ํ•ฉ์„ฑ๋‹จ๋ฉด C~F๋Š” ์ˆ˜ํ‰๊ท ์—ด์ด ๋ฐœ์ƒํ•˜์˜€๋‹ค. ์ „๋‹จ๋ฉด์— SFRC๊ฐ€ ์‚ฌ์šฉ๋œ ๋‹จ๋ฉด B๋Š” 2๊ฐœ์˜ ์‚ฌ์ธ์žฅ ๊ท ์—ด ํญ์ด ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ์„œ์„œํžˆ ์ฆ๊ฐ€ํ•˜๋ฉด์„œ ํŒŒ๊ดด๊ฐ€ ๋œ ๋ฐ˜๋ฉด, ํ•ฉ์„ฑ๋‹จ๋ฉด C~F๋Š” ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์—์„œ์˜ ์ˆ˜ํ‰์ „๋‹จ๊ท ์—ด๊ณผ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ํ•จ๊ป˜ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ๋˜ํ•œ, ์ธ์žฅ๋Œ€์— SFRC๊ฐ€ ์‚ฌ์šฉ๋œ ๋‹จ๋ฉด B~D๋Š” ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ๊ฐ€ ์‚ฌ์šฉ๋œ ๋‹จ๋ฉด๋“ค์— ๋น„ํ•ด ํœจ ๊ท ์—ด์ด ๋งŽ์ด ๋ถ„์‚ฐ๋˜์–ด ํœจ ๊ท ์—ด ๊ฐœ์ˆ˜๋Š” ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๊ณ  ๊ท ์—ด ๊ฐ„๊ฒฉ์€ ์ค„์–ด๋“ค์—ˆ๋‹ค.

ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ํŒŒ๊ดด ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์ž์„ธํžˆ ์‚ดํŽด๋ณด๋ฉด ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ(24 MPa) ๋‹จ๋ฉด์—์„œ ๋ฐœ์ƒํ•œ ํœจ ๋ฐ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ์ตœ์ข… ํŒŒ๊ดด์— ์˜ํ–ฅ์„ ์ฃผ์—ˆ๋‹ค. ์••์ถ•๋Œ€๊ฐ€ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ์ธ ๋‹จ๋ฉด C์™€ D๋Š” ์ƒ๋ถ€ ์ฝ˜ํฌ๋ฆฌํŠธ์—์„œ ๋ฐœ์ƒํ•œ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ๊ณ„๋ฉด์„ ๋”ฐ๋ผ ์ˆ˜ํ‰ ๊ท ์—ด ํŒŒ๊ดด๋ฅผ ๋ฐœ์ƒ์‹œ์ผฐ๊ณ , ์ธ์žฅ๋Œ€๊ฐ€ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ์ธ ๋‹จ๋ฉด E์™€ F๋Š” ํ•˜๋ถ€ ํœจ ๊ท ์—ด์ด ์‚ฌ์ธ์žฅ ๊ท ์—ด๋กœ ๋ฐœ์ „ํ•˜๋ฉด์„œ ๊ณ„๋ฉด์—์„œ ์ˆ˜ํ‰๊ท ์—ด ํŒŒ๊ดด๋ฅผ ๋ฐœ์ƒ์‹œ์ผฐ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F4.jpg

Fig. 4 Vertical load-center displacement relationship of SU-A~ SU-F

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F5.jpg

Fig. 5 Crack pattern of SU-A~SU-F at the end of test

3.2 ์‹คํ—˜์ฒด SR-A~SR-F

์‹คํ—˜์ฒด SR-A~SR-F๋Š” ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์ด ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด๋“ค๋กœ ๊ทธ ๊ฒฐ๊ณผ๋Š” Fig. 6, 7๊ณผ Table 4์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์‹คํ—˜ ๊ฐ•๋„๋Š” โ€˜SR-B (490 kN) > SR-F (402 kN) > SR-E (322 kN) > SR-C (292 kN) > SR-A(280 kN) > SR-D (248 kN)โ€™์ˆœ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด์ „ ์‹คํ—˜ ๊ฒฐ๊ณผ์™€ ๋‹ฌ๋ฆฌ ์••์ถ•๋Œ€๊ฐ€ ๊ณ ๊ฐ•๋„ SFRC์ธ ๋‹จ๋ฉด B, E, F๊ฐ€ ์••์ถ•๋Œ€๊ฐ€ ๋ณดํ†ต๊ฐ•๋„ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ์ธ ๋‹จ๋ฉด A, C, D๋ณด๋‹ค ํฐ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋ณด์˜€๋‹ค. ๋˜ํ•œ, ๋‹จ๋ฉด A๋Š” ๋‹จ๋ฉด D๋ณด๋‹ค 13% ํฐ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋ƒˆ๋‹ค.

Fig. 6์˜ ํ•˜์ค‘ ๋ณ€์œ„ ๊ด€๊ณ„๋ฅผ ์‚ดํŽด๋ณด๋ฉด, ๋‹จ๋ฉด B๋Š” ํœจ ํ•ญ๋ณต์ด ๋ฐœ์ƒํ•˜์—ฌ ์ตœ๋Œ€ ํ•˜์ค‘์ดํ›„ ์—ฐ์„ฑ๊ฑฐ๋™์„ ๋ณด์˜€๊ณ  ๋‹จ๋ฉด A์™€ ํ•ฉ์„ฑ๋‹จ๋ฉด C~F๋Š” ์ตœ๋Œ€ํ•˜์ค‘ ์ดํ›„ ํ•˜์ค‘์ด ์„œ์„œํžˆ ๊ฐ์†Œํ•˜๋Š” ์ „๋‹จํŒŒ๊ดด ๊ฑฐ๋™์„ ๋‚˜ํƒ€๋ƒˆ๋‹ค.

ํœจ ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•๋ฅ ์„ ์‚ดํŽด๋ณด๋ฉด, SR-B์™€ SR-F์—์„œ ํœจ ์ฒ ๊ทผ์ด ํ•ญ๋ณต๋ณ€ํ˜•๋ฅ ์— ๋„๋‹ฌํ•˜์˜€๋‹ค. SR-B๋Š” ํœจ ์ฒ ๊ทผ์ด ํ•ญ๋ณตํ•œ ์ดํ›„(/Resources/kci/JKCI.2015.27.5.501/images/PICF282.gif) ์—ฐ์„ฑ์ ์ธ ๊ฑฐ๋™์„ ๋ณด์ด๋ฉฐ ํœจ ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. SR-F๋Š” ํœจ ํ•ญ๋ณตํ•˜์˜€์ง€๋งŒ(/Resources/kci/JKCI.2015.27.5.501/images/PICF2B2.gif) ์‚ฌ์ธ์žฅ ๊ท ์—ด๊ณผ ๊ณ„๋ฉด์˜ ์ˆ˜ํ‰๊ท ์—ด์— ํ•˜์ค‘์ด ์ง‘์ค‘๋˜๋ฉด์„œ ์ตœ์ข…์ ์œผ๋กœ ์ „๋‹จํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค.

Fig. 7์€ ์ตœ์ข…ํŒŒ๊ดด ๊ท ์—ด ์–‘์ƒ์„ ๋‚˜ํƒ€๋‚ด๋Š” ๊ฒƒ์œผ๋กœ ๋‹จ์ผ๋‹จ๋ฉด B๋Š” ํœจ ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๊ณ , ๋‹จ์ผ๋‹จ๋ฉด A์™€ ํ•ฉ์„ฑ๋‹จ๋ฉด C์™€ D๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด์— ์˜ํ•ด, ํ•ฉ์„ฑ๋‹จ๋ฉด E์™€ F๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด๊ณผ ์ˆ˜ํ‰๊ท ์—ด์— ์˜ํ•ด ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ๊ฒฝ์šฐ, ์ „๋‹จ์—ฐ๊ฒฐ์žฌ์— ์˜ํ•ด ์ˆ˜ํ‰๊ท ์—ด์ด ์–ต์ œ๋˜์–ด ์ˆ˜์ง์ „๋‹จ ํŒŒ๊ดด๊ฐ€ ์ง€๋ฐฐ์ ์ด์—ˆ๋‹ค. ๋‹ค๋งŒ, ๋‹จ๋ฉด E์™€ F๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด ๋ฐœ์ƒ ํ›„ ์ˆ˜ํ‰๊ท ์—ด์— ์˜ํ•ด ํ•˜์ค‘์ด ๊ฐ์†Œํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F6.jpg

Fig. 6 Vertical load-center displacement relationship of SR-A~ SR-F

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F7.jpg

Fig. 7 Crack pattern of SR-A~SR-F at the end of test

Table 4 Test results of specimen 1-A~1-D

Specimens

/Resources/kci/JKCI.2015.27.5.501/images/PIC67DC.gif (MPa)

/Resources/kci/JKCI.2015.27.5.501/images/PIC681B.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC681C.gif

(kN)

/Resources/kci/JKCI.2015.27.5.501/images/PIC683D.gif1)

(kN)

Code prediction (kN)

Failure mode5)

24 MPa

60 MPa

/Resources/kci/JKCI.2015.27.5.501/images/PIC686D.gif

24 MPa

60 MPa

/Resources/kci/JKCI.2015.27.5.501/images/PIC687D.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC687E.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC688F.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC6890.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC68A0.gif

/Resources/kci/JKCI.2015.27.5.501/images/PIC68A1.gif

SU-A

21

-

21

-

78

-

68

76

-

-

-

-

1.15

1.02

-

-

DT

SU-B

-

56

56

3.93

204

-

-

-

110

117

164

-

1.85

1.74

1.25

-

DT

SU-C

21

56

43

3.93

136

604

30

34

62

65

92

198

1.49

1.38

1.12

3.05

DT+HS

SU-D

21

56

34

3.93

114

507

50

56

29

31

43

198

1.44

1.31

1.22

2.56

DT+HS

SU-E

21

56

34

3.93

75

333

38

42

49

52

72

198

0.87

0.80

0.68

1.68

DT+HS

SU-F

21

56

43

3.93

75

333

18

20

81

86

120

198

0.76

0.71

0.54

1.68

DT+HS

SR-A

22

-

22

-

140

-

69

77

-

-

-

-

2.02

1.81

-

-

DT

SR-B

-

59

59

4.87

245

-

-

-

113

120

203

-

2.16

2.05

1.21

-

Flexure

SR-C

22

59

45

4.87

146

649

30

34

63

67

113

757

1.55

1.44

1.01

0.86

DT

SR-D

22

59

36

4.87

124

551

51

57

30

32

54

757

1.53

1.40

1.19

0.73

DT

SR-E

22

59

36

4.87

161

716

39

43

50

53

90

757

1.81

1.68

1.26

0.95

DT+HS

SR-F

22

59

45

4.87

201

893

18

21

83

88

149

757

1.98

1.85

1.20

1.18

DT+HS

1)/Resources/kci/JKCI.2015.27.5.501/images/PIC69AC.gif, /Resources/kci/JKCI.2015.27.5.501/images/PIC69AD.gif= Shear span, /Resources/kci/JKCI.2015.27.5.501/images/PIC69BE.gif=Distance from extreme compression fiber to centroid of tension reinforcement

2)/Resources/kci/JKCI.2015.27.5.501/images/PIC69BF.gif=/Resources/kci/JKCI.2015.27.5.501/images/PIC69DF.gif(24MPa)+/Resources/kci/JKCI.2015.27.5.501/images/PIC69F0.gif(60MPa); 3)/Resources/kci/JKCI.2015.27.5.501/images/PIC69F1.gif=/Resources/kci/JKCI.2015.27.5.501/images/PIC6A01.gif(24MPa)+/Resources/kci/JKCI.2015.27.5.501/images/PIC6A02.gif(60MPa); 4)/Resources/kci/JKCI.2015.27.5.501/images/PIC6A13.gif=/Resources/kci/JKCI.2015.27.5.501/images/PIC6A14.gif(24MPa)+/Resources/kci/JKCI.2015.27.5.501/images/PIC6A24.gif(60MPa)

5)DT: Diagonal Tension, HS: Horizontal Shear

4. ์‹คํ—˜๋ณ€์ˆ˜ ๋ถ„์„ ๋ฐ ํ˜„ํ–‰๊ธฐ์ค€๊ณผ์˜ ๋น„๊ต

4.1 ์„ค๊ณ„๋ณ€์ˆ˜์˜ ์˜ํ–ฅ

์„ค๊ณ„๋ณ€์ˆ˜์˜ ์˜ํ–ฅ์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•ด Fig. 8์— ์ „๋‹จ์ฒ ๊ทผ๋น„์™€ ์œ ํšจ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„์— ๋”ฐ๋ฅธ ์ „๋‹จ๊ฐ•๋„๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋ƒˆ๋‹ค. Fig. 8(a)๋Š” ์ตœ์†Œ ์ˆ˜ํ‰์ „๋‹จ ๋ณด๊ฐ•๊ทผ ์‚ฌ์šฉ์— ๋”ฐ๋ฅธ ์ „๋‹จ๊ฐ•๋„ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋‹จ์ผ ๋‹จ๋ฉด A์™€ B์˜ ๊ฒฝ์šฐ 450 mm๊ฐ„๊ฒฉ(d/2 ์ด์ƒ)์œผ๋กœ ๋ฐฐ์น˜๋œ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ์— ์˜ํ•ด ์ „๋‹จ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ํ•ฉ์„ฑ๋‹จ๋ฉด C์™€ D๋Š” ์ „๋‹จ์—ฐ๊ฒฐ์žฌ์— ๋”ฐ๋ฅธ ์ „๋‹จ๊ฐ•๋„ ์ฆ๊ฐ€๊ฐ€ ๋ฐœ์ƒํ•˜์ง€ ์•Š์•˜๊ณ  ํ•ฉ์„ฑ๋‹จ๋ฉด E์™€ F๋Š” ์ „๋‹จ์—ฐ๊ฒฐ์žฌ ๋ณด๊ฐ•์— ๋”ฐ๋ผ ์ „๋‹จ๊ฐ•๋„๊ฐ€ 2๋ฐฐ ์ด์ƒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค.

Fig. 8(b-1)์€ SFRC๊ฐ€ ์ธ์žฅ์ธก์— ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด๋“ค์˜ ๊ฐ•๋„๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์—ฌ๊ธฐ์„œ, ๊ฐ€๋กœ์ถ•์€ ๋‹จ๋ฉด์ ๋น„๋กœ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„๋ฅผ ํ‰๊ท ํ•œ ์œ ํšจ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„์— ๋”ฐ๋ฅธ ์ „๋‹จ๊ฐ•๋„ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋Œ€์ฒด๋กœ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ์˜ ์œ ๋ฌด์™€ ๊ด€๊ณ„์—†์ด ๊ณ ๊ฐ•๋„ SFRC ๋‹จ๋ฉด์ด ์ฆ๊ฐ€ํ•˜๋ฉด์„œ ๋น„๋ก€์ ์œผ๋กœ ์ „๋‹จ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์˜ˆ์™ธ์ ์œผ๋กœ A๋‹จ๋ฉด์ด ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์žˆ๋Š” ๊ฒฝ์šฐ์— ๊ฐ•๋„๊ฐ€ ํฌ๊ฒŒ ๋ฐœํ˜„๋˜์—ˆ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F8.jpg

Fig. 8 Effects of test parameters

๋ฐ˜๋ฉด, SFRC๊ฐ€ ์••์ถ•๋Œ€์— ๋ณด๊ฐ•๋œ ๋‹จ๋ฉด(Fig. 8(b-2))์—์„œ๋Š” ์ˆ˜ํ‰์ „๋‹จ ๋ณด๊ฐ•๊ทผ์ด ์‚ฌ์šฉ๋œ ๊ฒฝ์šฐ SFRC ๋ฉด์ ์— ๋น„๋ก€ํ•˜์—ฌ ์ „๋‹จ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์˜€์ง€๋งŒ ์ˆ˜ํ‰์ „๋‹จ ๋ณด๊ฐ•๊ทผ์ด ์—†๋Š” ๊ฒฝ์šฐ ์••์ถ•๋Œ€์˜ SFRC์— ๋”ฐ๋ฅธ ์ „๋‹จ๊ฐ•๋„ ์ฆ๊ฐ€๊ฐ€ ๋ฐœ์ƒํ•˜์ง€ ์•Š์•˜๋‹ค. ์ด๋Š” ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์—†๋Š” ํ•ฉ์„ฑ๋‹จ๋ฉด E์™€ F์—์„œ๋Š” ๊ณ„๋ฉด์—์„œ ๋ฐœ์ƒํ•œ ์ˆ˜ํ‰๊ท ์—ด์— ์˜ํ•ด ์••์ถ•๋Œ€์˜ SFRC๊ฐ€ ์ œ ์—ญํ• ์„ ํ•˜์ง€ ๋ชปํ–ˆ๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ๋ฐ˜๋ฉด์— ์ˆ˜ํ‰์ „๋‹จ ๋ณด๊ฐ•๊ทผ์ด ์žˆ๋Š” ๊ฒฝ์šฐ๋Š” ๊ณ„๋ฉด์—์„œ์˜ ์ˆ˜ํ‰๊ท ์—ด์ด ์–ต์ œ๋˜์–ด ์••์ถ•๋Œ€์˜ SFRC๊ฐ€ ์ „๋‹จ๊ฐ•๋„์— ํฌ๊ฒŒ ๊ธฐ์—ฌํ•˜์˜€๋‹ค.

4.2 ์ „๋‹จ์ฒ ๊ทผ์˜ ์ „๋‹จ๊ฐ•๋„ ๊ธฐ์—ฌ๋„

์ „๋‹จ์ฒ ๊ทผ์˜ ์ „๋‹จ๊ฐ•๋„ ๊ธฐ์—ฌ๋„๋ฅผ ์‚ดํŽด๋ณด๊ธฐ ์œ„ํ•ด Fig. 9์— ํ•˜์ค‘๊ณผ ์ „๋‹จ์ฒ ๊ทผ ๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์ˆ˜ํ‰๊ท ์—ด ๋ฐ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ์˜ˆ์ƒ๋˜๋Š” ์œ„์น˜์— ์ฒ ๊ทผ์šฉ ๋ณ€ํ˜•๋ฅ  ๊ฒŒ์ด์ง€ 4๊ฐœ๋ฅผ ๋ถ€์ฐฉํ•˜์˜€๋‹ค. ์‹คํ—˜์ฒด SR-B๋Š” L2 ์œ„์น˜์˜ ์ „๋‹จ์ฒ ๊ทผ์ด ํ•ญ๋ณต์„ ๊ฒฝํ—˜ํ•˜์˜€๊ณ , SR-E์™€ F๋Š” L2์™€ R2 ์œ„์น˜์˜ ์ „๋‹จ์ฒ ๊ทผ์ด ํ•ญ๋ณตํ•˜์˜€๋‹ค. SR-E์™€ F๋Š” ์ „๋‹จ์ฒ ๊ทผ์ด ํ•ญ๋ณตํ•œ ์ดํ›„ ํ•ญ๋ณต ๋ณ€ํ˜•๋ฅ ์˜ 10๋ฐฐ ์ด์ƒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ด๋Š” ์ „๋‹จ์ฒ ๊ทผ์ด ์ˆ˜ํ‰์ „๋‹จ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ์ˆ˜์ง์ „๋‹จ์—๋„ ๊ธฐ์—ฌํ•œ ๊ฒƒ์œผ๋กœ SR-E์™€ F๊ฐ€ ๋ฌดํšก๋ณด๊ฐ• ์‹คํ—˜์ฒด์ธ SU-E์™€ F๋ณด๋‹ค 2๋ฐฐ ์ด์ƒ ์ „๋‹จ๊ฐ•๋„๊ฐ€ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•œ ์›์ธ์ด๋‹ค.

๊ฐ•์„ฌ์œ ๊ฐ€ ๋ณด๊ฐ•๋œ ๋‹จ๋ฉด์˜ ์œ„์น˜์— ๋”ฐ๋ผ ์ „๋‹จ์ฒ ๊ทผ์˜ ๊ธฐ์—ฌ๋„ ์ฐจ์ด๋ฅผ ๋ณด์˜€๋‹ค. SFRC๊ฐ€ ์ธ์žฅ๋Œ€์— ์œ„์น˜ํ•œ ๋‹จ๋ฉด C์™€ D์—์„œ๋Š” ์ „๋‹จ์ฒ ๊ทผ์ด ํ•ญ๋ณตํ•˜์ง€ ์•Š์•˜์ง€๋งŒ, ์••์ถ•๋Œ€์— ์œ„์น˜ํ•œ ๋‹จ๋ฉด E์™€ F์—์„œ๋Š” ์ „๋‹จ์ฒ ๊ทผ์ด ํ•ญ๋ณตํ•˜์˜€๊ณ  ํฐ ๋ณ€ํ˜•์„ ๋ณด์˜€๋‹ค. ์ด๋Š” Fig. 10์—์„œ์™€ ๊ฐ™์ด ์ „๋‹จ์ฒ ๊ทผ์˜ ๊ธฐ์—ฌ๋„๊ฐ€ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„์— ๋”ฐ๋ฅธ ์••์ถ•๋Œ€ ๊นŠ์ด(c)์™€ ์ธ์žฅ๋Œ€ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ฐ•์„ฌ์œ  ์‚ฌ์šฉ์— ๋”ฐ๋ฅธ ์‚ฌ์ธ์žฅ ๊ท ์—ด ํญ์— ์˜ํ–ฅ์„ ๋ฐ›์€ ๊ฒƒ์ด๋‹ค. ์••์ถ•๋Œ€๊ฐ€ ๋ณดํ†ต๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์ธ SR-A, C, D์˜ ๊ฒฝ์šฐ ํœจ ๋ชจ๋ฉ˜ํŠธ์— ์˜ํ•œ ์••์ถ•๋Œ€ ๊นŠ์ด๊ฐ€ ํฌ๊ธฐ ๋•Œ๋ฌธ์— ์ƒ๋Œ€์ ์œผ๋กœ ์‚ฌ์ธ์žฅ ๊ท ์—ด ๊ธธ์ด๊ฐ€ ์งง์•„์ง€๊ณ , ์••์ถ•๋Œ€๊ฐ€ ๊ณ ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ์ธ SR-B, E, F์˜ ๊ฒฝ์šฐ ์••์ถ•๋Œ€ ๊นŠ์ด๊ฐ€ ์ž‘๊ธฐ ๋•Œ๋ฌธ์— ์‚ฌ์ธ์žฅ ๊ท ์—ด ๊ธธ์ด๊ฐ€ ๊ธธ์–ด์ง„๋‹ค(๊ฐ€๋ ฅ์ ์œผ๋กœ ๊ฐˆ์ˆ˜๋ก ๊ท ์—ด ๊ฐ๋„๊ฐ€ ๊ฐ์†Œํ•˜๊ธฐ ๋•Œ๋ฌธ). ๋”ฐ๋ผ์„œ, ์ „๋‹จ์ฒ ๊ทผ์„ ๊ด€ํ†ตํ•˜๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด ๊ธธ์ด๊ฐ€ ์ƒ๋Œ€์ ์œผ๋กœ ๊ธด SR-B, E, F์˜ ์ „๋‹จ์ฒ ๊ทผ ๋ณ€ํ˜•๋ฅ ์ด ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๊ณ  ์ „๋‹จ์ฒ ๊ทผ์ด ์ˆ˜์ง์ „๋‹จ์— ํฌ๊ฒŒ ๊ธฐ์—ฌํ•˜๋ฉฐ ์ „๋‹จ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๋˜ํ•œ, ์‹คํ—˜์ฒด SR-B, C, D๋Š” ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ์ธ์žฅ๋Œ€์— ์œ„์น˜ํ•œ ์‚ฌ์ธ์žฅ ๊ท ์—ด ํญ์ด ์–ต์ œ๋˜์—ˆ๊ณ , ๊ทธ์— ๋”ฐ๋ผ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ๊ด€ํ†ตํ•œ ์ „๋‹จ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•๋ฅ ์ด ๊ฐ•์„ฌ์œ ๊ฐ€ ์••์ถ•๋Œ€์— ์œ„์น˜ํ•œ SR-E์™€ F์— ๋น„ํ•ด ์ž‘๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

SR-A๊ฐ€ SR-D๋ณด๋‹ค ํฐ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋ณด์ธ ๊ฒƒ๋„ ์‚ฌ์ธ์žฅ ๊ท ์—ด ํญ์— ์˜ํ–ฅ์„ ๋ฐ›์€ ๊ฒƒ์ด๋‹ค. SR-A๋Š” ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ์ „๋‹จ์ฒ ๊ทผ์„ ๊ด€ํ†ตํ•˜๋ฉด์„œ ์ „๋‹จ๊ฐ•๋„๊ฐ€ SU-A๋ณด๋‹ค 78% ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. SR-D๋„ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ์ „๋‹จ์ฒ ๊ทผ์„ ๊ด€ํ†ตํ•˜์˜€์ง€๋งŒ, ์ „๋‹จ๊ฐ•๋„๊ฐ€ SU-D์— ๋น„ํ•ด 9% ์†Œํญ ์ƒ์Šนํ•˜์˜€๋‹ค. ์ด๋Š” Fig. 10(c)์™€ ๊ฐ™์ด ์‚ฌ์ธ์žฅ ๊ท ์—ด ํญ์ด ์ธ์žฅ๋Œ€ ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ์–ต์ œ๋˜์—ˆ๊ณ , ์ด์— ๋”ฐ๋ผ ์ „๋‹จ์ฒ ๊ทผ ๋ณ€ํ˜•๋ฅ ๋„ SR-A ์‹คํ—˜์ฒด์— ๋น„ํ•ด ์ƒ๋Œ€์ ์œผ๋กœ ๋‚ฎ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

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Fig. 9 Measured load โ€“ strain relationship of stirrups

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Fig. 10 Contribution of shear reinforcement and steel fibers

4.3 ์ˆ˜์ง์ „๋‹จ๊ฐ•๋„ ๊ธฐ์ค€์‹๊ณผ์˜ ๋น„๊ต

๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ ํ•ฉ์„ฑ ๋ณด์˜ ์ˆ˜์ง ์ „๋‹จ๊ฐ•๋„๋ฅผ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•ด ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํ˜„ํ–‰ ๊ธฐ์ค€์‹(ACI318, ACI544)์œผ๋กœ ์˜ˆ์ธกํ•œ ๊ฐ’์„ ๋น„๊ตํ•˜์˜€๋‹ค(Table 4). ๋‹จ์ผ๋‹จ๋ฉด์€ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„ ์‹์ธ ์‹ (1), (2) ๋˜๋Š” SFRC ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„์‹์ธ ์‹ (3)์„ ์‚ฌ์šฉํ•˜์—ฌ ์˜ˆ์ธกํ•˜์˜€๊ณ , ํ•ฉ์„ฑ๋‹จ๋ฉด์€ ๊ฐ ์š”์†Œ์˜ ํŠน์„ฑ์— ๋งž๊ฒŒ ๊ณ„์‚ฐํ•œ ๋’ค ๋‹จ์ˆœ ๋ˆ„๊ฐ€๋ฒ•์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค.

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Fig. 11 Strength predictions of current design codes

Fig. 11(a)์˜ ACI318 ์˜ˆ์ธก ๊ฒฐ๊ณผ๋ฅผ ์‚ดํŽด๋ณด๋ฉด, ์ˆ˜ํ‰๊ท ์—ด์ด ๋ฐœ์ƒํ•œ SU-E์™€ F ์‹คํ—˜์ฒด๋ฅผ ์ œ์™ธํ•˜๊ณ  ๋ชจ๋‘ ์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€์ง€๋งŒ, ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์˜ํ–ฅ์ด ๋ฐ˜์˜๋˜์ง€ ์•Š์•˜๊ธฐ ๋•Œ๋ฌธ์— ๊ฐ•์„ฌ์œ ๊ฐ€ ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด๋“ค์— ๋Œ€ํ•ด ํฌ๊ฒŒ ๊ณผ์†Œํ‰๊ฐ€ํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF2F2.gif =1.31~2.16). SU-E์™€ F ์‹คํ—˜์ฒด๋Š” ๊ณ„๋ฉด์—์„œ ๋ฐœ์ƒํ•œ ์ˆ˜ํ‰์ „๋‹จ ๊ท ์—ด์— ์˜ํ•ด ์••์ถ•๋Œ€์˜ SFRC๊ฐ€ ์ „๋‹จ๊ฐ•๋„์— ๊ธฐ์—ฌํ•˜์ง€ ๋ชปํ•˜์—ฌ ํฌ๊ฒŒ ๋น„์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค. ์‹คํ—˜๊ฐ•๋„๊ฐ€ SFRC๋ฅผ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ๋กœ ๊ฐ€์ •ํ•œ ์ „๋‹จ๊ฐ•๋„ /Resources/kci/JKCI.2015.27.5.501/images/PICF302.gif์™€ /Resources/kci/JKCI.2015.27.5.501/images/PICF332.gif์—๋„ ๋ฏธ์น˜์ง€ ๋ชปํ•˜์˜€๋‹ค.

๋ฐ˜๋ฉด์— ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์˜ํ–ฅ์„ ๋ฐ˜์˜ํ•˜๊ธฐ ์œ„ํ•ด ACI544์—์„œ ์ œ๊ณตํ•˜๋Š” ์ „๋‹จ๊ฐ•๋„ ์‹(์‹ (3))์„ ์‚ฌ์šฉํ•˜์—ฌ ์˜ˆ์ธกํ•œ ๊ฒฝ์šฐ๋Š” Fig. 11(b)์™€ ๊ฐ™์ด SU-E์™€ F ์‹คํ—˜์ฒด(์ˆ˜ํ‰์ „๋‹จํŒŒ๊ดด)๋ฅผ ์ œ์™ธํ•˜๊ณ  ๋Œ€๋ถ€๋ถ„ ์ž˜ ์˜ˆ์ธกํ•˜์˜€๋‹ค. ํŠนํžˆ, ๊ฐ•์„ฌ์œ ๊ฐ€ ๋ณด๊ฐ•๋œ ์‹คํ—˜์ฒด๋“ค์— ๋Œ€ํ•ด์„œ๋Š” ์ •ํ™•ํžˆ ์˜ˆ์ธกํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF343.gif = 1.01~1.26).

๋˜ํ•œ Fig. 11์—์„œ ๋‹จ๋ฉด์ด 24 MPa๋กœ ํšก๋ณด๊ฐ•๋œ ์‹คํ—˜์ฒด SR-A๋Š” ์‹คํ—˜๊ฐ’์ด ACI318 ์ „๋‹จ๊ฐ•๋„ ์ผ๋ฐ˜์‹์œผ๋กœ ์˜ˆ์ธกํ•œ ๊ฐ’์˜ 2๋ฐฐ์ด์ƒ ๋‚˜์™”๋Š”๋ฐ, ์ด๋Š” ์‚ฌ์ธ์žฅ๊ท ์—ด๋ฉด์ด ์ „๋‹จ์ฒ ๊ทผ์„ ๊ด€ํ†ตํ•˜๋ฉด์„œ ์ „๋‹จ์ฒ ๊ทผ์ด ์ „๋‹จ๊ฐ•๋„ ์ฆ๊ฐ€์— ๊ธฐ์—ฌํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค(Fig. 9 ์ฐธ์กฐ).

4.4 ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„

๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ๋กœ ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์—์„œ์˜ ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„๋ฅผ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•ด ๋ณธ ์‹คํ—˜๊ณผ ๊ธฐ์กด์—ฐ๊ตฌ ๊ฒฐ๊ณผ๋ฅผ ์ˆ˜ํ‰์ „๋‹จ๋ ฅ์— ๊ด€ํ•œ ํ˜„ํ–‰ ๊ธฐ์ค€์‹๊ณผ ๋น„๊ตํ•˜์˜€๋‹ค.

๋ณธ ์‹คํ—˜์—์„œ๋Š” ์••์ถ•๋Œ€๊ฐ€ ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด ์ƒ๋ถ€์— ์œ„์น˜ํ•˜๊ธฐ ๋•Œ๋ฌธ์— Fig. 2์˜ Case 1 ๋ฐฉ๋ฒ•์œผ๋กœ ์ˆ˜ํ‰์ „๋‹จ๋ ฅ(/Resources/kci/JKCI.2015.27.5.501/images/PICF373.gif)์„ ๊ณ„์‚ฐํ•˜์˜€๋‹ค(Table 4). SR-C์™€ D ์‹คํ—˜์ฒด๋Š” ์ˆ˜ํ‰๊ท ์—ด์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š์•˜๊ธฐ ๋•Œ๋ฌธ์— ๋น„๊ต์—์„œ ์ œ์™ธ์‹œ์ผฐ๋‹ค.

๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ๊ณ„๋ฉด์˜ ์ˆ˜ํ‰์ „๋‹จ๋ ฅ์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•ด ๋ณธ ์‹คํ—˜๊ฒฐ๊ณผ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ Banta20)์˜ ๊ฐ•์„ฌ์œ ๊ฐ€ ์‚ฌ์šฉ๋œ UHPC (Ultra High Performance Concrete)์™€ ๊ฒฝ๋Ÿ‰ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ˆ˜ํ‰์ „๋‹จ ํ‘ธ์‰ฌ์˜คํ”„ ์‹คํ—˜(push-off test) ๊ฒฐ๊ณผ๋ฅผ ํ•จ๊ป˜ ๋น„๊ตํ•˜์˜€๋‹ค. ๋ณธ ์‹คํ—˜์—์„œ๋Š” ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์˜ ๊ฑฐ์นœ๋ฉด ํ˜•์„ฑ์„ ์œ„ํ•ด ์ง€์—ฐ์ œ(์‹œ๋ฉ˜ํŠธ์˜ ์–‘์ƒ ์†๋„๋ฅผ ์ง€์—ฐ์‹œ์ผœ์ฃผ๋Š” ํ™”ํ•™์•ฝํ’ˆ)์™€ ์ˆ˜์••์„ ํ™œ์šฉํ•˜์—ฌ Fig. 12์™€ ๊ฐ™์ด ๊ณ„๋ฉด์˜ ๊ณจ์žฌ๋ฅผ ์ตœ๋Œ€ํ•œ ๋“œ๋Ÿฌ๋‚˜๋„๋ก ์ฒ˜๋ฆฌํ•˜์˜€๋‹ค. ๋ฐ˜๋ฉด, Banta๋Š” ์ฃผ๋กœ ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด๋“ค์„ ๋Œ€์ƒ์œผ๋กœ ์ „๋‹จ์ฒ ๊ทผ๋น„์™€ ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„์˜ ๊ด€๊ณ„๋ฅผ ์‚ดํŽด๋ณด์•˜๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F12.jpg

Fig. 12 The interface condition of specimens

ํ˜„ํ–‰ ๊ธฐ์ค€์‹์œผ๋กœ๋Š” ACI31813), AASHTO LRFD18), CSA19)์—์„œ ์ œ์‹œํ•˜๋Š” ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„ ์‹์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ACI318์€ ์ตœ์†Œ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์—†๊ฑฐ๋‚˜ ํ‘œ๋ฉด์„ ๊ฑฐ์น ๊ฒŒ ๋งŒ๋“ค์ง€ ์•Š์€ ๊ฒฝ์šฐ ์ˆ˜ํ‰์ „๋‹จ๋ ฅ์„ 0.56 MPa๋กœ, ์ตœ์†Œ ์ „๋‹จ์—ฐ๊ฒฐ์žฌ๊ฐ€ ์žˆ๊ณ  ํ‘œ๋ฉด์ด ์•ฝ 6 mm ๊นŠ์ด๋กœ ๊ฑฐ์น ๊ฒŒ ๋งŒ๋“ค์–ด์ง„ ๊ฒฝ์šฐ /Resources/kci/JKCI.2015.27.5.501/images/PICF3B2.gif(MPa)๋กœ ์ •์˜ํ•˜๊ณ  ์žˆ๋‹ค. ์ด๋•Œ ์ˆ˜ํ‰์ „๋‹จ๋ ฅ์ด 3.5 MPa ์ด์ƒ์ธ ๊ฒฝ์šฐ๋Š” ์ „๋‹จ๋งˆ์ฐฐ ์„ค๊ณ„๋ฒ•์„ ๋”ฐ๋ฅด๋„๋ก ํ•œ๋‹ค. ๋ฐ˜๋ฉด์— AASHTO LRFD์™€ CSA๋Š” Table 5์™€ ๊ฐ™์ด ๊ณ„๋ฉด์˜ ์ƒํƒœ์— ๋”ฐ๋ผ ์ ์ฐฉ๋ ฅ(/Resources/kci/JKCI.2015.27.5.501/images/PICF3C3.gif)์™€ ๋งˆ์ฐฐ๊ณ„์ˆ˜(/Resources/kci/JKCI.2015.27.5.501/images/PICF3D3.gif)๋ฅผ ๋‹ฌ๋ฆฌํ•˜์—ฌ ์‹ (7)๊ณผ ๊ฐ™์ด ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„์‹์„ ์‚ฐ์ •ํ•œ๋‹ค. ๋‹จ, ์ „๋‹จ์ฒ ๊ทผ๊ณผ ๋ถ„๋ฆฌ ํƒ€์„ค๋œ ๊ณ„๋ฉด์ด ์ˆ˜์งํ•œ ๊ฒฝ์šฐ์— ํ•œํ•œ๋‹ค.

/Resources/kci/JKCI.2015.27.5.501/images/Figure_CONCRETE_27_5_04_F13.jpg

Fig. 13 Horizontal shear stress for specimens

Table 5 Horizontal shear stress without shear reinforcement

Code

Interface condition

/Resources/kci/JKCI.2015.27.5.501/images/PIC79DD.gif (MPa)

/Resources/kci/JKCI.2015.27.5.501/images/PIC79DE.gif

AASHTO18)

Clean, free of laitance, with surface intentionally roughened to an amplitude of 6 mm

1.66

1.0

Clean, free of laitance, but not intentionally roughened

0.52

0.6

CSA19)

For concrete placed against hardened concrete with the surface clean and intentionally roughened to a full amplitude of at least 5 mm

0.50

1.0

For concrete placed against hardened concrete with the surface clean but not intentionally roughened

0.25

0.6

/Resources/kci/JKCI.2015.27.5.501/images/PICF480.gif (MPa)       (7)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2015.27.5.501/images/PICF491.gif์€ ์ „๋‹จ๋ฉด(shear plane)์˜ ์ˆ˜์ง๋ฐฉํ–ฅ์œผ๋กœ ์ž‘์šฉํ•˜๋Š” ์˜๊ตฌํ•˜์ค‘์ด๊ณ  /Resources/kci/JKCI.2015.27.5.501/images/PICF4B1.gif๋Š” ์ด ๋‹จ๋ฉด์ ์ด๋‹ค.

Fig. 13์€ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํ˜„ํ–‰๊ธฐ์ค€์‹์„ ๋น„๊ตํ•œ ๊ฒƒ์œผ๋กœ ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ˆ˜ํ‰์ „๋‹จํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•œ SU์‹คํ—˜์ฒด(ํฐ์ƒ‰), SR-E, F (๊ฒ€์ •์ƒ‰)์™€ ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์€ Banta ์‹คํ—˜์ฒด(ํšŒ์ƒ‰)๋ฅผ ํ•จ๊ป˜ ๋น„๊ตํ•˜์˜€๋‹ค. ๋จผ์ €, Banta ์‹คํ—˜์ฒด์— ๋Œ€ํ•ด 3๊ฐ€์ง€ ๊ธฐ์ค€(์‹ค์„ ) ๋ชจ๋‘ ์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค. AASHTO LRFD์™€ CSA๋Š” Clamping stress์— ๋Œ€ํ•œ ๊ฒฝํ–ฅ์„ฑ์„ ์ž˜ ๋ฐ˜์˜ํ•˜์—ฌ ์ •ํ™•ํžˆ ์˜ˆ์ธกํ•˜์˜€์ง€๋งŒ, ACI318์€ ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ ์ „๋‹จ์ฒ ๊ทผ์˜ ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜์ง€ ๋ชปํ•˜์—ฌ ์ „๋‹จ์ฒ ๊ทผ์ด ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด์— ๋Œ€ํ•ด ๋ณด์ˆ˜์ ์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF4F1.gif1.77~5.12).

๋ฐ˜๋ฉด์— ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•œ ๋ณธ ์‹คํ—˜ ๊ฒฐ๊ณผ์— ๋Œ€ํ•ด CSA๋Š” ๋Œ€๋ถ€๋ถ„ ๋ณด์ˆ˜์ ์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๊ณ (/Resources/kci/JKCI.2015.27.5.501/images/PICF530.gif1.89~3.42), ACI318์€ ์ „๋‹จ์ฒ ๊ทผ์ด ์—†๋Š” SU ์‹คํ—˜์ฒด์— ๋Œ€ํ•ด์„œ๋งŒ ๋ณด์ˆ˜์ ์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF560.gif1.68~3.05). ASSHTO LRFD๋Š” ๋Œ€๋ถ€๋ถ„ ๋น„์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์—ฌ ์•ˆ์ „์„ฑ ๋ฌธ์ œ๊ฐ€ ์šฐ๋ ค๋œ๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF5CE.gif0.57~1.13). ํŠนํžˆ ์••์ถ•๋Œ€์— SFRC๊ฐ€ ์‚ฌ์šฉ๋œ SU-E์™€ SU-F ์‹คํ—˜์ฒด์— ๋Œ€ํ•ด์„œ๋Š” /Resources/kci/JKCI.2015.27.5.501/images/PICF5EF.gif๋กœ ํฌ๊ฒŒ ๋น„์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค.

์‹คํ—˜๊ฒฐ๊ณผ์™€ ํ˜„ํ–‰ ๊ธฐ์ค€์„ ๋น„๊ตํ•œ ๊ฒฐ๊ณผ, ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์€ SFRC ์‹คํ—˜์ฒด๋Š” AASHTO LRFD์—์„œ ์ œ์•ˆํ•˜๋Š” /Resources/kci/JKCI.2015.27.5.501/images/PICF5FF.gif=0.52, /Resources/kci/JKCI.2015.27.5.501/images/PICF610.gif=0.6์„ ์‚ฌ์šฉํ•œ ์˜ˆ์ธก์ด ๊ฐ€์žฅ ์ •ํ™•ํ•˜์˜€๊ณ , ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•œ ์‹คํ—˜์ฒด๋Š” ์ˆ˜ํ‰ ์ „๋‹จ๋ณด๊ฐ•์žฌ์˜ ์œ ๋ฌด์— ๋”ฐ๋ผ ์ฐจ๋“ฑ์„ ๋‘๋Š” ACI318 ๋ฐฉ๋ฒ•์ด ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ๊ฐ€์žฅ ์ž˜ ์˜ˆ์ธกํ•˜์˜€๋‹ค.

5. ๊ฒฐ    ๋ก 

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ํ”„๋ฆฌ์บ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ํ˜„์žฅํƒ€์„ค ์ฝ˜ํฌ๋ฆฌํŠธ ํ•ฉ์„ฑ๋ณด์˜ ์ „๋‹จ๊ฑฐ๋™์„ ์‚ดํŽด๋ณด๊ธฐ ์œ„ํ•ด ๊ณ ๊ฐ•๋„ ๊ฐ•์„ฌ์œ ์ฝ˜ํฌ๋ฆฌํŠธ(60 MPa)์™€ ๋ณดํ†ต๊ฐ•๋„ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ(24 MPa)์˜ ๋‹จ๋ฉด์ ๋น„์™€ ์ „๋‹จ์ฒ ๊ทผ๋น„๋ฅผ ๋ณ€์ˆ˜๋กœ ๋‹จ์ˆœ์ง€์ง€๋ณด ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ํ†ตํ•ด ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ํ•ฉ์„ฑ๋‹จ๋ฉด ์„ค๊ณ„์‹œ ๊ณ ๋ ค์‚ฌํ•ญ ๋ฐ ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ์ „๋‹จ ๊ฑฐ๋™์„ ์‚ดํŽด๋ณด์•˜๊ณ  ๊ทธ ๊ฒฐ๊ณผ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์š”์•ฝํ•  ์ˆ˜ ์žˆ๋‹ค.

1)๊ณ ๊ฐ•๋„ ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ(SFRC)๊ฐ€ ์ธ์žฅ๋Œ€์— ์‚ฌ์šฉ๋œ ํ•ฉ์„ฑ๋ณด์—์„œ๋Š” ์ˆ˜ํ‰์ „๋‹จ์„ ์œ„ํ•œ ์ „๋‹จ์ฒ ๊ทผ์ด ์‚ฌ์šฉ๋˜์ง€ ์•Š์€ ๊ฒฝ์šฐ, ํ˜„ํ–‰๊ธฐ์ค€์— ๋”ฐ๋ผ ์ˆ˜ํ‰์ „๋‹จํŒŒ๊ดด์— ์˜ํ•ด ๊ฐ•๋„๊ฐ€ ๊ฒฐ์ •๋˜๋Š” ๊ฒƒ์œผ๋กœ ์˜ˆ์ธก๋˜์—ˆ์œผ๋‚˜, ์ธ์žฅ๋Œ€์— ๋ณด๊ฐ•๋œ ๊ฐ•์„ฌ์œ ์— ์˜ํ•ด ํœจ ์ธ์žฅ๊ท ์—ด์ด ๊ณ„๋ฉด๊ท ์—ด๋กœ ๋ฐœ์ „ํ•˜๋Š” ๊ฒƒ์„ ์–ต์ œํ•˜์—ฌ ์˜ˆ์ƒ ๊ฐ•๋„๋ฅผ ์ดˆ๊ณผํ•˜๋Š” ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์ด๋กœ ์ธํ•˜์—ฌ, ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์œ ๋ฌด์™€ ๊ด€๊ณ„์—†์ด SFRC์˜ ๋‹จ๋ฉด์ ๋น„๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉด์„œ ๋น„๋ก€์ ์œผ๋กœ ํ•ฉ์„ฑ๋‹จ๋ฉด์˜ ์ „๋‹จ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค.

2)SFRC๊ฐ€ ์••์ถ•๋Œ€์— ์‚ฌ์šฉ๋œ ํ•ฉ์„ฑ๋ณด์—์„œ๋Š” ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์ด ์‚ฌ์šฉ๋œ ๊ฒฝ์šฐ, ํ•ฉ์„ฑ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„๊ฐ€ SFRC์˜ ๋‹จ๋ฉด์ ๋น„์— ๋น„๋ก€ํ•˜์—ฌ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋‚˜, ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์ด ์‚ฌ์šฉ๋˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์—๋Š” ํ˜„ํ–‰๊ธฐ์ค€์˜ ์˜ˆ์ธก๊ฒฐ๊ณผ์™€ ๊ฐ™์ด ๊ณ„๋ฉดํŒŒ๊ดด๋กœ ์ธํ•˜์—ฌ ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜์ง€ ์•Š์•˜๋‹ค. ์ด๋Š” ์ธ์žฅ๋Œ€์˜ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ์—์„œ ๋ฐœ์ƒํ•œ ํœจ ๊ท ์—ด์ด ์‰ฝ๊ฒŒ ๊ณ„๋ฉดํŒŒ๊ดด๋กœ ์ง„์ „๋˜์—ˆ๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

3)์ตœ์†Œ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ, ์••์ถ•๋Œ€์— SFRC๋ฅผ ์‚ฌ์šฉํ•œ ํ•ฉ์„ฑ๋ณด๊ฐ€ ์ธ์žฅ๋Œ€์— SFRC๋ฅผ ์‚ฌ์šฉํ•œ ํ•ฉ์„ฑ๋ณด๋ณด๋‹ค ํฐ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋ฐœํœ˜ํ•˜์˜€๋‹ค. ๊ทธ ์ด์œ ๋Š” ๊ฐ•์„ฌ์œ ์˜ ์˜ํ–ฅ๋ณด๋‹ค๋Š” ์••์ถ•๋Œ€์— ๊ณ ๊ฐ•๋„์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ์‚ฌ์šฉํ•จ์œผ๋กœ์จ ์ธ์žฅ๋Œ€์˜ ๊นŠ์ด๊ฐ€ ๊ธธ์–ด์ ธ์„œ ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์ด ์ˆ˜์ง์ „๋‹จ์— ๊ธฐ์—ฌํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

4)์ตœ์†Œ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ•์„ ์‚ฌ์šฉํ•˜๋Š” ๊ฒฝ์šฐ, ACI544์—์„œ ์ œ๊ณตํ•˜๋Š” ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ์ „๋‹จ๊ฐ•๋„์‹๊ณผ ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฐ•๋„ ์ผ๋ฐ˜์‹์„ ๋‹จ์ˆœ ๋ˆ„๊ฐ€๋ฒ•์œผ๋กœ ๊ณ„์‚ฐํ•  ๊ฒฝ์šฐ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์ž˜ ์˜ˆ์ธกํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF640.gif=1.01~1.26). ์ตœ์†Œ์ˆ˜ํ‰์ „๋‹จ๋ณด๊ฐ• ์—†์ด ์••์ถ•๋Œ€์— SFRC๋ฅผ ์‚ฌ์šฉํ•œ ํ•ฉ์„ฑ๋ณด์˜ ๊ฒฝ์šฐ, ์ˆ˜ํ‰์ „๋‹จํŒŒ๊ดด๋กœ ์ธํ•˜์—ฌ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๊ณผ๋Œ€ํ‰๊ฐ€ํ•˜์˜€๋‹ค.

5)๊ฐ•์„ฌ์œ ๊ฐ€ ์‚ฌ์šฉ๋œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ณ„๋ฉด์˜ ์ˆ˜ํ‰์ „๋‹จ์— ๋Œ€ํ•œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํ˜„ํ–‰๊ธฐ์ค€์„ ๋น„๊ตํ•˜๋ฉด ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด์— ๋Œ€ํ•ด์„œ๋Š” ACI318, AASHTO LRFD, CSA ๋ชจ๋‘ ์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€์ง€๋งŒ, ACI318์€ ์ „๋‹จ์ฒ ๊ทผ์˜ ์˜ํ–ฅ์„ ๋ฐ˜์˜ํ•˜์ง€ ๋ชปํ•˜์—ฌ ๋ณด์ˆ˜์ ์œผ๋กœ ์˜ˆ์ธกํ•˜์˜€๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF67F.gif1.77~5.12). ๋ฐ˜๋ฉด์— ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•œ ์‹คํ—˜์ฒด์— ๋Œ€ํ•ด์„œ๋Š” ACI318์ด ๊ฐ€์žฅ ์ž˜ ์˜ˆ์ธกํ•˜์˜€๊ณ  AASHTO LRFD ์‹์€ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ํฌ๊ฒŒ ๋น„์•ˆ์ „์ธก์œผ๋กœ ์˜ˆ์ธกํ•˜์—ฌ ์•ˆ์ „์„ฑ ๋ฌธ์ œ๊ฐ€ ์šฐ๋ ค๋œ๋‹ค(/Resources/kci/JKCI.2015.27.5.501/images/PICF69F.gif0.57~ 1.13). ๋”ฐ๋ผ์„œ, AASHTO LRFD ์‹์œผ๋กœ ๊ฐ•์„ฌ์œ  ์ฝ˜ํฌ๋ฆฌํŠธ ๊ณ„๋ฉด์˜ ์ˆ˜ํ‰์ „๋‹จ๊ฐ•๋„ ์˜ˆ์ธก์‹œ ๊ณ„๋ฉด ์ฒ˜๋ฆฌ์™€ ๊ด€๊ณ„์—†์ด ๊ณ„๋ฉด์ฒ˜๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์€ ์ƒํƒœ๋กœ ๊ฐ€์ •ํ•˜์—ฌ ์„ค๊ณ„ํ•˜์—ฌ์•ผ ํ•œ๋‹ค.

Acknowledgements

๋ณธ ์—ฐ๊ตฌ๋Š” ๊ตญํ† ํ•ด์–‘๋ถ€๊ฐ€ ์ฃผ๊ด€ํ•˜๊ณ  ํ•œ๊ตญ๊ฑด์„ค๊ตํ†ต๊ธฐ์ˆ ํ‰๊ฐ€์›์ด ์‹œํ–‰ํ•˜๋Š” 2011๋…„ R&D ์ •์ฑ…์ธํ”„๋ผ์‚ฌ์—…(11๊ธฐ์ˆ  ํ‘œ์ค€ํ™” 07-01)์œผ๋กœ ์ด๋ฃจ์–ด์ง„ ๊ฒƒ์œผ๋กœ ์ด์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

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