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Journal of the Korea Concrete Institute

J Korea Inst. Struct. Maint. Insp.
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  • Korea Citation Index (KCI)

  1. ์ •ํšŒ์›,๋Œ€๊ตฌ๋Œ€ํ•™๊ต ๊ฑด์ถ•๊ณตํ•™๊ณผ ๊ต์ˆ˜, ๊ต์‹ ์ €์ž
  2. ์ •ํšŒ์›,๊ฐ•๋ฆ‰์›์ฃผ๋Œ€ํ•™๊ต ๊ฑด์„คํ™˜๊ฒฝ๊ณตํ•™๊ณผ ๊ต์ˆ˜
  3. ์ •ํšŒ์›,๋‹จ๊ตญ๋Œ€ํ•™๊ต ํ† ๋ชฉํ™˜๊ฒฝ๊ณตํ•™๊ณผ ๋ถ€๊ต์ˆ˜



๋ฉด๋‚ด์ „๋‹จ, ํƒ„์†Œ์„ฌ์œ , ํƒ„์†Œ๋ณด๊ฐ•๊ทผ, ์ „๋‹จ๊ฐ•๋„, ์ˆ˜์ •์••์ถ•์žฅ์ด๋ก 
In-plane shear, Carbon fiber, CFRP rebar, Shear strength, Modified compression field theory

1. ์„œ ๋ก 

์ง€๊ธˆ๊นŒ์ง€ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ๋Œ€๋ถ€๋ถ„์€ ์ฒ ๊ทผ์„ ๋ณด๊ฐ•์žฌ๋กœ ์‚ฌ์šฉํ•˜๋Š” ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ํ˜•ํƒœ๋กœ ๋งŒ๋“ค์–ด์ ธ ์™”๋‹ค. ์••์ถ•์— ๋น„ํ•ด ์ธ์žฅ์— ์•ฝํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์—ญํ•™์  ๋‹จ์ ์„ ์ฒ ๊ทผ์œผ๋กœ ๋ณด์™„ํ•จ์œผ๋กœ์จ ๋‹ค์–‘ํ•œ ์ž‘์šฉ๋ ฅ์— ๋Œ€ํ•ด ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ์ฒ ๊ทผ์˜ ๋ณตํ•ฉ ์ž‘์šฉ์œผ๋กœ ํšจ์œจ์ ์œผ๋กœ ์ €ํ•ญํ•  ์ˆ˜ ์žˆ๋„๋ก ํ•จ์œผ๋กœ์จ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํšจ์šฉ์„ฑ์„ ํฌ๊ฒŒ ํ–ฅ์ƒ์‹œ์ผฐ๋‹ค. ์ด์ฒ˜๋Ÿผ ์ฒ ๊ทผ์€ ๋ณด๊ฐ•์žฌ๋กœ์„œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์—์„œ ์ถฉ์‹คํ•œ ์—ญํ• ์„ ์ˆ˜ํ–‰ํ•˜์ง€๋งŒ, ๋ถ€์‹์— ์ทจ์•ฝํ•œ ์ ๊ณผ ๋†’์€ ๋ฐ€๋„๋กœ ์ธํ•ด ๊ตฌ์กฐ๋ฌผ์˜ ์ด์ค‘๋Ÿ‰์„ ์ฆ๊ฐ€์‹œํ‚ค๋Š” ๋“ฑ์˜ ์•ฝ์ ๋„ ๊ฐ€์ง€๊ณ  ์žˆ์–ด์„œ, ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ๋‚ด๊ตฌ์„ฑ๊ณผ ๊ฒฝ์ œ์„ฑ์— ์ œ์•ฝ์  ์š”์ธ์œผ๋กœ ์ž‘์šฉํ•˜๊ธฐ๋„ ํ•œ๋‹ค(Angst et al., 2012; Abbas and Shafiee, 2020; Han et al., 2021). ์ด๋Ÿฌํ•œ ๊ด€์ ์—์„œ ์ฒ ๊ทผ์˜ ๋Œ€์ฒด์žฌ๋กœ์„œ ๊ฐ€๋ณ๊ณ  ๊ฐ•๋„๊ฐ€ ๋†’์œผ๋ฉฐ ๋ถ€์‹์— ๋งค์šฐ ๊ฐ•ํ•œ ์„ฌ์œ ๋ณด๊ฐ• ํด๋ฆฌ๋จธ(Fiber Reinforced Polymer, FRP) ๋ณด๊ฐ•๊ทผ์— ๋Œ€ํ•ด ํฌ๊ฒŒ ์ฃผ๋ชฉํ•˜๊ณ  ์žˆ๋‹ค(Oh et al., 2008; Nanni et al., 2014).

FRP ๋ณด๊ฐ•๊ทผ์€ ์‚ฌ์šฉ๋˜๋Š” ์„ฌ์œ ์˜ ์ข…๋ฅ˜์— ๋”ฐ๋ผ ์—ฌ๋Ÿฌ ๊ฐ€์ง€๋กœ ๋ถ„๋ฅ˜๋˜๋Š”๋ฐ, ๋Œ€ํ‘œ์ ์œผ๋กœ ์œ ๋ฆฌ์„ฌ์œ (Glass fiber)๋ฅผ ์‚ฌ์šฉํ•œ GFRP, ํƒ„์†Œ์„ฌ์œ (Carbon fiber)๋ฅผ ์‚ฌ์šฉํ•˜๋Š” CFRP, ์•„๋ผ๋ฏธ๋“œ์„ฌ์œ (Aramid fiber)๋ฅผ ์‚ฌ์šฉํ•˜๋Š” AFRP ๋ณด๊ฐ•๊ทผ ๋“ฑ์ด ์žˆ์œผ๋ฉฐ, ์ด ์ค‘์—์„œ CFRP ๋ณด๊ฐ•๊ทผ์€ ๋งค์šฐ ๋†’์€ ๊ฐ•๋„์™€ ๊ฐ•์„ฑ์„ ๋‚˜ํƒ€๋‚ด์–ด ๊ณ ๊ฐ•๋„ ๋ณด๊ฐ•์ด ํ•„์š”ํ•œ ๊ฒฝ์šฐ์— ๋งŽ์ด ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค.

์ฒ ๊ทผ ๋Œ€์ฒด์žฌ๋กœ์„œ FRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ํœจ, ์ „๋‹จ, ๋ถ€์ฐฉ ๋“ฑ์˜ ๋‹ค์–‘ํ•œ ๊ตฌ์กฐ์  ๊ฑฐ๋™ ํŠน์„ฑ์— ๋Œ€ํ•˜์—ฌ ๊ทธ๋™์•ˆ ๋งŽ์€ ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์–ด ์™”์œผ๋‚˜, ์—ฌ์ „ํžˆ ๋ช…ํ™•ํ•˜๊ฒŒ ๊ทœ๋ช…๋˜์ง€ ์•Š์€ ๋ถ€๋ถ„๋“ค์ด ๋‚จ์•„์žˆ๋‹ค(Mahroug et al., 2014; El Ghadioui et al., 2020; Choi et al., 2021). ํŠนํžˆ ์ „๋‹จ๊ฑฐ๋™์˜ ๊ฒฝ์šฐ ํœจ๊ฑฐ๋™์— ๋น„ํ•ด ์ƒ๋Œ€์ ์œผ๋กœ FRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์— ๋Œ€ํ•œ ์‹คํ—˜์  ์—ฐ๊ตฌ๊ฐ€ ์ถฉ๋ถ„ํ•˜์ง€ ์•Š์œผ๋ฉฐ, ๊ด€๋ จ ์„ค๊ณ„๊ธฐ์ค€์—์„œ๋Š” ์ฒ ๊ทผ์— ๋น„ํ•ด ์ž‘์€ FRP์˜ ๊ฐ•์„ฑ์œผ๋กœ ์ธํ•œ ์ฐจ์ด๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๊ธฐ์กด์˜ ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ „๋‹จ์„ค๊ณ„ ๋ชจ๋ธ์‹์„ ์•ฝ๊ฐ„ ์ˆ˜์ •ํ•œ ํ˜•ํƒœ๋กœ ์‚ฌ์šฉํ•˜๊ณ  ์žˆ๋‹ค(ACI Committee 440, 2015; AASHTO, 2017; CSA, 2012; JSCE, 1997).

ํ•œํŽธ, ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ์ „๋‹จํŒŒ๊ดด ๋ฉ”์ปค๋‹ˆ์ฆ˜์€ ์ง€๊ธˆ๊นŒ์ง€ ๋‹ค์–‘ํ•œ ์ด๋ก ์  ๋ฐฉ๋ฒ•์œผ๋กœ ๊ทœ๋ช…ํ•˜๊ณ ์ž ๋…ธ๋ ฅํ•ด ์™”๋‹ค(Ritter, 1899; Mitchell and Collins, 1974, Vecchio and Collins, 1986). ๊ทธ ์ค‘์—์„œ Vecchio and Collins(1986)์ด ์ œ์•ˆํ•œ ์ˆ˜์ •์••์ถ•์žฅ ์ด๋ก (Modified Compression Field Theory, ์ดํ•˜ MCFT)์€ ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์—์„œ์˜ ์ ํ•ฉ์กฐ๊ฑด, ํ‰ํ˜•์กฐ๊ฑด ๋ฐ ์žฌ๋ฃŒ์˜ ๊ตฌ์„ฑ๋ฐฉ์ •์‹์„ ํ† ๋Œ€๋กœ ํ•œ ์‘๋ ฅ์žฅ ํ•ด์„๋ฐฉ๋ฒ•์œผ๋กœ, ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฑฐ๋™ ์˜ˆ์ธก์— ๋งŽ์ด ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค(Park, 1999; Bentz et al., 2006). ์ด์™€ ๊ฐ™์€ ํ•ด์„๋ฐฉ๋ฒ•์€ ์ฒ ๊ทผ ๋Œ€์‹  FRP ๋ณด๊ฐ•๊ทผ์˜ ์žฌ๋ฃŒํŠน์„ฑ์„ ๊ณ ๋ คํ•จ์œผ๋กœ์จ FRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ์ „๋‹จ๊ฑฐ๋™ ํŠน์„ฑ๋„ ํ•ฉ๋ฆฌ์ ์œผ๋กœ ํ‰๊ฐ€ํ•  ์ˆ˜ ์žˆ์„ ๊ฒƒ์œผ๋กœ ๊ธฐ๋Œ€ํ•  ์ˆ˜ ์žˆ๋‹ค.

๊ทธ๋Ÿฌํ•œ ๊ด€์ ์—์„œ ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ „๋‹จ๋ฒฝ๊ณผ ๊ฐ™์€ ๋ฉด๋‚ด ์ „๋‹จ์„ ๋ฐ›๋Š” ๊ฒฝ์šฐ์— ๋Œ€ํ•ด, CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฑฐ๋™ํŠน์„ฑ์„ MCFT ์ด๋ก ์— ๊ธฐ๋ฐ˜ํ•˜์—ฌ ํ‰๊ฐ€ํ•˜๊ณ , ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฒฝ์šฐ์™€ ๋น„๊ตํ•˜์—ฌ ๋ถ„์„ํ•˜๊ณ ์ž ํ•˜์˜€๋‹ค.

2. ์ˆ˜์ •์••์ถ•์žฅ ์ด๋ก 

์ˆ˜์ •์••์ถ•์žฅ ์ด๋ก ์€ 1986๋…„ Vecchio, F.J.์™€ Collins, M.P.์— ์˜ํ•œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ํŒจ๋„์‹คํ—˜ ๊ฒฐ๊ณผ์— ๊ทผ๊ฑฐํ•˜์—ฌ ๊ธฐ์กด์˜ ์••์ถ•์žฅ ์ด๋ก ์œผ๋กœ๋ถ€ํ„ฐ ์ œ์•ˆ๋˜์—ˆ๋Š”๋ฐ, ์ง€๊ธˆ๊นŒ์ง€๋„ ์—ฌ์ „ํžˆ ์ •ํ™•ํ•œ ๊ฑฐ๋™ ์˜ˆ์ธก ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค(Vecchio and Collins, 1988; Feng et al., 2021). ์›๋ž˜์˜ ์••์ถ•์žฅ ์ด๋ก ์—์„œ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ๊ฐ€ ๊ท ์—ด์ด ์ƒ๊ธด ํ›„์—๋Š” ์ธ์žฅ์‘๋ ฅ์€ ๋ฐ›์„ ์ˆ˜ ์—†๋‹ค๊ณ  ๊ฐ€์ •ํ•˜์˜€๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์‹ค์ œ๋กœ๋Š” ์ธ์žฅ์‘๋ ฅ์ด ์ž‘์šฉํ•˜๊ณ  ์žˆ์Œ์„ ๋งŽ์€ ์‹คํ—˜์„ ํ†ตํ•ด ํ™•์ธํ•˜์˜€์œผ๋ฉฐ, ๊ทธ๋ž˜์„œ ์ˆ˜์ •์••์ถ•์žฅ ์ด๋ก ์—์„œ๋Š” ์ „๋‹จ์‘๋ ฅ์˜ ์ •ํ™•ํ•œ ์˜ˆ์ธก์„ ์œ„ํ•ด ๊ท ์—ด ์ดํ›„์— ์ฝ˜ํฌ๋ฆฌํŠธ๊ฐ€ ๋ฐ›๋Š” ์ธ์žฅ์‘๋ ฅ์„ ๊ณ ๋ คํ•˜๊ณ  ์žˆ๋‹ค.

2.1 ๊ธฐ๋ณธ๊ฐ€์ •

์ˆ˜์ •์••์ถ•์žฅ ์ด๋ก ์€ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ์‚ฌํ•ญ๋“ค์„ ๊ฐ€์ •ํ•˜๊ณ  ์žˆ๋‹ค.

(1) ์™ธ๋ถ€ ํ•˜์ค‘์ž‘์šฉ์— ์˜ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ฏธ์†Œ ์š”์†Œ์— ์ž‘์šฉํ•˜๋Š” ์ „๋‹จ์‘๋ ฅ๊ณผ ์ˆ˜์ง์‘๋ ฅ์€ ๊ท ์ผํ•˜๊ฒŒ ๋ถ„ํฌํ•œ๋‹ค.

(2) ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋Š” ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์š”์†Œ์˜ ํ‰๊ท  ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋กœ ๋‚˜ํƒ€๋‚ธ๋‹ค.

(3) ์ฝ˜ํฌ๋ฆฌํŠธ ์š”์†Œ์—์„œ์˜ ์ฃผ์‘๋ ฅ ๋ฐฉํ–ฅ๊ณผ ์ฃผ๋ณ€ํ˜•๋ฅ  ๋ฐฉํ–ฅ์€ ๋™์ผํ•˜๋‹ค.

(4) ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ๋ณด๊ฐ•๊ทผ์€ ์ƒํ˜ธ๊ฐ„ ๋ถ€์ฐฉ์Šฌ๋ฆฝ์ด ์ „ํ˜€ ๋ฐœ์ƒํ•˜์ง€ ์•Š๋Š” ์™„์ „๋ถ€์ฐฉ์ƒํƒœ๋กœ ๊ณ ๋ คํ•œ๋‹ค.

(5) ๋ณด๊ฐ•๊ทผ์— ์ž‘์šฉํ•˜๋Š” ์‘๋ ฅ์€ ์ถ•๋ฐฉํ–ฅ ์‘๋ ฅ๋งŒ ๊ณ ๋ คํ•˜๊ณ , ์ „๋‹จ์‘๋ ฅ์€ ๊ณ ๋ คํ•˜์ง€ ์•Š๋Š”๋‹ค.

2.2 ํ‰ํ˜•์กฐ๊ฑด

Fig. 1๊ณผ ๊ฐ™์ด ์ฝ˜ํฌ๋ฆฌํŠธ ์š”์†Œ์— $x$ ๋ฐ $y$ ๋ฐฉํ–ฅ์œผ๋กœ ๋ณด๊ฐ•๊ทผ์ด ์ง๊ต ๊ฒฉ์žํ˜•ํƒœ๋กœ ๋ฐฐ์น˜๋˜์–ด ์žˆ๊ณ , ์š”์†Œ์˜ ๋ชจ์„œ๋ฆฌ ํ‰๋ฉด์— ์ž‘์šฉํ•˜๋Š” ์‘๋ ฅ์€ ๊ฐ๊ฐ ์ˆ˜์ง์‘๋ ฅ $f_{x}$, $f_{y}$์™€ ์ „๋‹จ์‘๋ ฅ $v_{xy}$๋กœ ๊ตฌ์„ฑ๋œ ์‘๋ ฅ์ƒํƒœ๋ฅผ ๊ณ ๋ คํ•œ๋‹ค. $x$ ๋ฐ $y$ ๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ์˜ ๋ณด๊ฐ•๊ทผ๋น„๋ฅผ ๊ฐ๊ฐ $\rho_{x}$, $\rho_{y}$๋กœ ๋‚˜ํƒ€๋‚ด๊ณ , ๋ณด๊ฐ•๊ทผ์— ์ž‘์šฉํ•˜๋Š” ์‘๋ ฅ์„ ๊ฐ๊ฐ $f_{sx}$์™€ $f_{sy}$๋กœ ๋‚˜ํƒ€๋‚ด๋ฉด, ํž˜์˜ ํ‰ํ˜•์กฐ๊ฑด์œผ๋กœ๋ถ€ํ„ฐ ๋‹ค์Œ์˜ ๊ด€๊ณ„์‹์„ ์–ป์„ ์ˆ˜ ์žˆ๋‹ค.

(1)
$f_{x}=\rho_{x}f_{sx}+f_{c1}-v_{xy}\cot\theta$
(2)
$f_{y}=\rho_{y}f_{sy}+f_{c1}-v_{xy}\tan\theta$
(3)
$v_{xy}=\left(f_{c1}+f_{c2}\right)/(\tan\theta +\cot\theta)$

์—ฌ๊ธฐ์„œ, $f_{c1}$๊ณผ $f_{c2}$๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์— ์ž‘์šฉํ•˜๋Š” ์ฃผ์‘๋ ฅ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

Fig. 1 Stresses in element
../../Resources/ksm/jksmi.2024.28.4.13/fig1.png

2.3 ์ ํ•ฉ์กฐ๊ฑด

์„ธ ๊ฐ€์ง€ ๋ณ€ํ˜•๋ฅ  ๊ตฌ์„ฑ์š”์†Œ $\epsilon_{x}$, $\epsilon_{y}$ ๋ฐ $\gamma_{xy}$๋ฅผ ์•Œ๋ฉด ๋ณ€ํ˜•๋ฅ ์— ๋Œ€ํ•œ ๋ชจ์–ด ์›(Mohrโ€˜s circle) ์„ ํ†ตํ•ด์„œ ๋‹ค๋ฅธ ๋ฐฉํ–ฅ์˜ ๋ณ€ํ˜•๋ฅ ์„ ๊ตฌํ•  ์ˆ˜ ์žˆ์œผ๋ฉฐ, Fig. 2์— ๋‚˜ํƒ€๋‚ธ $\epsilon_{x}$ ๋ฐ $\epsilon_{y}$์™€ ์ฃผ๋ณ€ํ˜•๋ฅ  $\epsilon_{1}$ ๋ฐ $\epsilon_{2}$ ์‚ฌ์ด์˜ ๊ด€๊ณ„์‹์€ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ํ‘œํ˜„๋œ๋‹ค.

(4)
$\gamma_{xy}=\dfrac{2(\epsilon_{x}+\epsilon_{2})}{\tan\theta}$
(5)
$\epsilon_{1}=\epsilon_{x}+\epsilon_{y}+\epsilon_{2}$
(6)
$\tan^{2}\theta =\dfrac{\epsilon_{x}+\epsilon_{2}}{\epsilon_{y}+\epsilon_{2}}=\dfrac{\epsilon_{1}-\epsilon_{y}}{\epsilon_{1}-\epsilon_{x}}$
Fig. 2 Average and principal strains in element
../../Resources/ksm/jksmi.2024.28.4.13/fig2.png

2.4 ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„

์š”์†Œ์— ์ž‘์šฉํ•˜๋Š” ํ‰๊ท  ์‘๋ ฅ๊ณผ ์ฒ ๊ทผ๊ณผ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํ‰๊ท  ๋ณ€ํ˜•๋ฅ ์„ ์—ฐ๊ฒฐํ•˜๊ธฐ ์œ„ํ•œ ๋ณด๊ฐ•๊ทผ ๋ฐ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํ‰๊ท  ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

์ฒ ๊ทผ์˜ ๊ฒฝ์šฐ, Fig. 3(a)์™€ ๊ฐ™์€ ์ด์„ ํ˜• ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ์ ์šฉํ•  ์ˆ˜ ์žˆ์œผ๋ฉฐ, ์ฝ˜ํฌ๋ฆฌํŠธ์— ๋Œ€ํ•ด์„œ๋Š” Fig. 3(b)์™€ ๊ฐ™์€ ์••์ถ• ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ณก์„  ํ˜•ํƒœ๋ฅผ ๊ฐ€์ง„๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ฃผ์••์ถ•์‘๋ ฅ์€ ์ฃผ์••์ถ•๋ณ€ํ˜•๋ฅ  $\epsilon_{2}$๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ํ•จ๊ป˜ ํ•˜๋Š” ์ฃผ์ธ์žฅ๋ณ€ํ˜•๋ฅ  $\epsilon_{1}$์˜ ํ•จ์ˆ˜์ด๊ธฐ๋„ ํ•˜๋‹ค. ๋”ฐ๋ผ์„œ ์••์ถ•์— ์ˆ˜์ง์ธ ๋ฐฉํ–ฅ์œผ๋กœ ๋†’์€ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์„ ๋ฐ›๊ฒŒ ๋˜๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ์ผ์ถ• ์••์ถ•์‹œํ—˜์„ ํ†ตํ•ด ๊ตฌํ•œ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ ์— ๋น„ํ•ด ๋‚ฎ์€ ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์ด๋Ÿฌํ•œ ์ ์„ ๊ณ ๋ คํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ• ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„์‹์€ ์‹ (7)๊ณผ ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ๋‹ค.

(7)
$f_{c2}=\dfrac{f_{c}'}{0.8+0.34\epsilon_{1}/\epsilon_{c}'}\left[2\left(\dfrac{\epsilon_{2}}{\epsilon_{c}'}\right)-\left(\dfrac{\epsilon_{2}}{\epsilon_{c}'}\right)^{2}\right]$

๊ทธ๋ฆฌ๊ณ  ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ธ์žฅ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋Š” ๊ท ์—ด๋ฐœ์ƒ ์ด์ „์—๋Š” ์„ ํ˜•ํƒ„์„ฑ ๊ฑฐ๋™์œผ๋กœ ๊ณ ๋ คํ•˜๋ฉฐ, ๊ท ์—ด๋ฐœ์ƒ ์ดํ›„์—๋Š” ๋‹ค์Œ์˜ ๊ด€๊ณ„์‹์„ ์ ์šฉํ•  ์ˆ˜ ์žˆ๋‹ค.

(8)
$f_{c1}=\dfrac{0.33\sqrt{f_{c}'}}{1 +\sqrt{500\epsilon_{1}}}$
Fig. 3 Stress-strain relationships of steel reinforcement and concrete
../../Resources/ksm/jksmi.2024.28.4.13/fig3.png

2.5 ๊ท ์—ด๋ฉด์—์„œ์˜ ์‘๋ ฅ

์•ž์„œ ์–ธ๊ธ‰ํ•œ ์‘๋ ฅ ๋ฐ ๋ณ€ํ˜•๋ฅ ์€ ํ‰๊ท ๊ฐ’์— ๊ด€ํ•œ ๊ฒƒ์œผ๋กœ, ์š”์†Œ์— ์ž‘์šฉํ•˜๋Š” ์‹ค์ œ ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜๋ฉด ๋ณด๊ฐ•๊ทผ์˜ ์ธ์žฅ์‘๋ ฅ์€ ํ‰๊ท ๋ณด๋‹ค ๋†’์ง€๋งŒ ๊ท ์—ด ์ค‘๊ฐ„์—๋Š” ํ‰๊ท ๋ณด๋‹ค ๋‚ฎ๋‹ค. ๋ฐ˜๋ฉด์— ์ฝ˜ํฌ๋ฆฌํŠธ ์ธ์žฅ์‘๋ ฅ์€ ๊ท ์—ด์—์„œ 0์ด ๋˜๊ณ  ๊ท ์—ด ์‚ฌ์ด์˜ ์ค‘๊ฐ„์—์„œ๋Š” ํ‰๊ท ๋ณด๋‹ค ๋†’๋‹ค. ์ด์ถ• ์‘๋ ฅ์„ ๋ฐ›๋Š” ์š”์†Œ์˜ ๊ถ๊ทน์ ์ธ ํ•˜์ค‘ ์ €ํ•ญ ๋Šฅ๋ ฅ์€ ๊ท ์—ด์„ ๊ฐ€๋กœ์งˆ๋Ÿฌ ์ธ์žฅ๋ ฅ์„ ์ „๋‹ฌํ•˜๋Š” ๋ณด๊ฐ•๊ทผ์— ์˜ํ•ด ์ขŒ์šฐ๋  ์ˆ˜ ์žˆ๊ธฐ ๋•Œ๋ฌธ์— ์ด๋Ÿฌํ•œ ๊ตญ๋ถ€์ ์ธ ๋ณ€ํ™”์— ๋Œ€ํ•œ ๊ณ ๋ ค๋Š” ์ค‘์š”ํ•˜๋‹ค. ๊ท ์—ด๋ฉด์— ์ž‘์šฉํ•˜๋Š” ์‘๋ ฅ์ƒํƒœ๋Š” Fig. 4์™€ ๊ฐ™์ด ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ์œผ๋ฉฐ, ๊ท ์—ด๋ฉด์— ์ž‘์šฉํ•˜๋Š” ์ „๋‹จ์‘๋ ฅ์„ $v_{ci}$, ์••์ถ•์‘๋ ฅ์„ $f_{ci}$, ๊ท ์—ด๋ฉด์—์„œ $x$ ๋ฐ $y$๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ์— ์ž‘์šฉํ•˜๋Š” ์‘๋ ฅ์„ ๊ฐ๊ฐ $f_{sxcr}$๊ณผ $f_{sycr}$๋ผ๊ณ  ํ•˜๋ฉด, $f_{sxcr}$๊ณผ $f_{sycr}$๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™์€ ์‹์œผ๋กœ ๋‚˜ํƒ€๋‚ด์–ด์ง„๋‹ค.

(9)
$f_{sxcr}=\left(f_{x}+v_{xy}\cot\theta +v_{ci}\cot\theta\right)/\rho_{x}\le f_{\max ,\: x}$
(10)
$f_{sycr}=\left(f_{y}+v_{xy}\tan\theta -v_{ci}\tan\theta\right)/\rho_{y}\le f_{\max ,\: y}$

์—ฌ๊ธฐ์„œ, $f_{\max ,\: x}$์™€ $f_{\max ,\: y}$๋Š” ๊ฐ๊ฐ $x$, $y$๋ฐฉํ–ฅ์œผ๋กœ ๋ณด๊ฐ•๊ทผ์— ์ž‘์šฉํ•  ์ˆ˜ ์žˆ๋Š” ์ตœ๋Œ€์‘๋ ฅ์„ ์˜๋ฏธํ•˜๋ฉฐ, ์ฒ ๊ทผ์˜ ๊ฒฝ์šฐ์—๋Š” ํ•ญ๋ณต๊ฐ•๋„์— ํ•ด๋‹นํ•œ๋‹ค.

๊ท ์—ด๋ฉด์— ์ž‘์šฉํ•˜๋Š” ์ „๋‹จ์‘๋ ฅ $v_{ci}$๋Š” ๊ท ์—ดํญ($w$), ๊ณจ์žฌ์˜ ์ตœ๋Œ€์น˜์ˆ˜($a$) ๋“ฑ์„ ํฌํ•จํ•œ ๋‹ค์Œ ์‹์„ ๋งŒ์กฑํ•˜์—ฌ์•ผ ํ•œ๋‹ค (Walraven, 1981).

(11)
$v_{ci}\le\dfrac{0.18\sqrt{f_{c}'}}{0.31 + 24 w/(a + 16)}$

์œ„์˜ ์‹์—์„œ ๊ท ์—ดํญ, $w$๋Š” ๊ท ์—ด๋ฉด์—์„œ์˜ ํ‰๊ท  ๊ท ์—ดํญ์„ ์ฃผ์ธ์žฅ๋ณ€ํ˜•๋ฅ ($\epsilon_{1}$)๊ณผ ๊ท ์—ด๊ฐ„๊ฒฉ($s_{\theta}$)์˜ ๊ณฑ ํ˜•ํƒœ๋กœ ์‹ (12)์™€ ๊ฐ™์ด ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ์œผ๋ฉฐ, $s_{\theta}$๋Š” ์‹ (13)์„ ์ด์šฉํ•˜์—ฌ ๊ณ„์‚ฐํ•  ์ˆ˜ ์žˆ๋‹ค.

(12)
$w =\epsilon_{1}s_{\theta}$
(13)
$s_{\theta}=\dfrac{1}{\dfrac{\sin\theta}{s_{mx}}+\dfrac{\cos\theta}{s_{my}}}$

์œ„ ์‹์—์„œ $s_{mx}$์™€ $s_{my}$๋Š” ๊ฐ๊ฐ $x$๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ๊ณผ $y$๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ์˜ ๊ท ์—ด ์ œ์–ดํŠน์„ฑ์„ ๋‚˜ํƒ€๋‚ด๋Š” ๊ฐ’์ด๋‹ค.

Fig. 4 Local stresses at a cracked plane
../../Resources/ksm/jksmi.2024.28.4.13/fig4.png

3. ํ•ด์„๋ฐฉ๋ฒ• ๋ฐ ์กฐ๊ฑด

3.1 ํ•ด์„๋ฐฉ๋ฒ•

๋ฉด๋‚ด ์ „๋‹จ์„ ๋ฐ›๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฑฐ๋™ํŠน์„ฑ์— ๋Œ€ํ•œ MCFT์— ๊ทผ๊ฑฐํ•œ ํ•ด์„๊ณผ์ •์€ ์ฝ˜ํฌ๋ฆฌํŠธ ์š”์†Œ์— ์ž‘์šฉํ•˜๋Š” ์ธ์žฅ๋ฐฉํ–ฅ์˜ ์ฃผ๋ณ€ํ˜•๋ฅ ($\epsilon_{1}$)์„ ๋‹จ๊ณ„์ ์œผ๋กœ ์ฆ๊ฐ€์‹œํ‚ค๋ฉด์„œ, ๊ฐ ๋‹จ๊ณ„์˜ ์ฃผ๋ณ€ํ˜•๋ฅ ์„ ์œ ๋ฐœํ•˜๋Š” ์‘๋ ฅ์„ ๊ณ„์‚ฐํ•˜๋Š” ๊ณผ์ •์œผ๋กœ ์ง„ํ–‰๋œ๋‹ค. ์ด์ถ• ํ•˜์ค‘์„ ๋ฐ›๋Š” ๋ฉค๋ธŒ๋ ˆ์ธ ์š”์†Œ์˜ ์ „๋‹จ๊ฑฐ๋™์„ ๊ฒฐ์ •ํ•˜๋Š” ํ•ด์„์ ˆ์ฐจ๋Š” Fig. 5์™€ ๊ฐ™๋‹ค. ํ•ด์„ ์•Œ๊ณ ๋ฆฌ์ฆ˜์— ๋”ฐ๋ผ matlab ์†Œํ”„ํŠธ์›จ์–ด๋ฅผ ์ด์šฉํ•˜์—ฌ ๋ฉด๋‚ด ์ „๋‹จ๊ฑฐ๋™ ํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์„ ๊ฐœ๋ฐœํ•˜์˜€์œผ๋ฉฐ, Vecchio and Collins(1986)์™€ Bentz et al.(2006)์—์„œ ์ œ์‹œ๋œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ํŒ์š”์†Œ์— ๋Œ€ํ•œ ๋ฉด๋‚ด์ „๋‹จ๊ฑฐ๋™์— ๊ด€ํ•œ ๊ธฐ์กด ์‹คํ—˜๊ฒฐ๊ณผ์™€์˜ ๋น„๊ต๋ฅผ ํ†ตํ•ด ํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์˜ ์ •ํ™•์„ฑ์„ ๊ฒ€์ฆํ•˜์˜€๋‹ค. Bentz et al.(2006)์—์„œ๋Š” ๋‹ค์–‘ํ•œ ์ฒ ๊ทผ๋น„์˜ ๋ฉค๋ธŒ๋ ˆ์ธ ์š”์†Œ์— ๋Œ€ํ•œ ๋ฉด๋‚ด์ „๋‹จ์‹คํ—˜์˜ ๊ฒฐ๊ณผ์™€ MCFT ํ•ด์„ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•˜์—ฌ ์ œ์‹œํ•˜์˜€๋Š”๋ฐ, ๊ทธ๋“ค์ด ์ ์šฉํ•œ ์‹คํ—˜๊ฒฐ๊ณผ๋Š” $x$๋ฐฉํ–ฅ ์ฒ ๊ทผ๋น„๊ฐ€ 2.96%๋กœ ์ผ์ •ํ•˜๊ณ , $y$๋ฐฉํ–ฅ ์ฒ ๊ทผ๋น„๊ฐ€ ๊ฐ๊ฐ 0.33, 0.60, 0.97, 1.19, 1.79, 2.98%์ธ ์ด 6๊ฐ€์ง€ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ๊ฒƒ์ด๋‹ค. Fig. 6์€ Bentz et al.(2006)์—์„œ ์ œ์‹œ๋œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ์ด ์—ฐ๊ตฌ์—์„œ ์ ์šฉํ•œ ํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์„ ํ†ตํ•ด ์–ป์–ด์ง„ ํ•ด์„๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•˜์—ฌ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค.

Fig. 5 Algorithm flowchart for in-plane shear analysis
../../Resources/ksm/jksmi.2024.28.4.13/fig5.png
Fig. 6 Comparison of analytical results withBentz et al.(2006)
../../Resources/ksm/jksmi.2024.28.4.13/fig6.png

3.2 ํ•ด์„์กฐ๊ฑด

Bentz et al.(2006)์—์„œ ๊ณ ๋ คํ•œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๋™์ผํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ๋ฅผ ๋Œ€์ƒ์œผ๋กœ ํ•ด์„์„ ์‹ค์‹œํ•˜์˜€์œผ๋ฉฐ, ๋‹ค๋งŒ ์ฒ ๊ทผ์„ ๋ณด๊ฐ•๊ทผ์œผ๋กœ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์™€ ํ•จ๊ป˜ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๋ฅผ ์ ์šฉํ•˜์—ฌ ๊ฒ€ํ† ํ•˜์˜€๋‹ค. ๊ทธ๋“ค์ด ๊ณ ๋ คํ•œ ์‹คํ—˜์—์„œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„($f_{c}'$)๋Š” 42.6MPa์ด๋ฉฐ, ์ฒ ๊ทผ์€ ํ•ญ๋ณต๊ฐ•๋„ 470MPa์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์ด ์‹คํ—˜์—์„œ์™€ ๋™์ผํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ์••์ถ•๊ฐ•๋„์™€ ๋™์ผํ•œ ํฌ๊ธฐ ๋ฐ ๋ณด๊ฐ•๊ทผ๋น„๋ฅผ ๊ฐ€์ง„ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์— ๋Œ€ํ•˜์—ฌ ๋ฉด๋‚ด์ „๋‹จ ๊ฑฐ๋™์— ๋Œ€ํ•œ ํ•ด์„์„ ์‹ค์‹œํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ๋ฅผ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฒฝ์šฐ์™€ ๋น„๊ตํ•˜์˜€๋‹ค.

๋น„๊ตํ•ด์„์„ ์œ„ํ•ด ์ ์šฉํ•œ ์ฒ ๊ทผ ๋ฐ ํƒ„์†Œ๋ณด๊ฐ•๊ทผ์˜ ๋ฌผ์„ฑ๊ฐ’์€ Table 1๊ณผ ๊ฐ™๋‹ค. ์ฒ ๊ทผ์€ ์™„์ „ํƒ„์†Œ์„ฑ ๊ฑฐ๋™์„ ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๊ฐ€์ •ํ•˜์˜€์œผ๋ฉฐ, ํƒ„์†Œ๋ณด๊ฐ•๊ทผ์€ ์ธ์žฅ๊ฐ•๋„์— ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€ ํƒ„์„ฑ๊ฑฐ๋™์„ ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค.

Table 1 Mechanical properties of steel and CFRP rebars

Type

Steel rebar

CFRP rebar

Yield strength [MPa]

470

-

Yield strain

0.00235

-

Tensile strength [MPa]

-

2,300

Ultimate tensile strain

-

0.01769

Elastic modulus [MPa]

200,000

130,000

4. ํ•ด์„๊ฒฐ๊ณผ ๋ฐ ๋ถ„์„

Fig. 7(a)์™€ (b)๋Š” ๊ฐ๊ฐ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์™€ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ๋ฉด๋‚ด ์ „๋‹จ๊ฑฐ๋™์˜ ํ•ด์„๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค. ๊ทธ ๊ฒฐ๊ณผ๋ฅผ ์‚ดํŽด๋ณด๋ฉด, ๋ฉด๋‚ด์ „๋‹จ๊ฐ•๋„์˜ ๊ฒฝ์šฐ์—๋Š” ๋‚ฎ์€ ํšก๋ณด๊ฐ•๊ทผ๋น„์—์„œ๋Š” ๋™์ผํ•œ ๋ณด๊ฐ•๊ทผ๋น„์˜ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋น„ํ•ด CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ ๋” ํฐ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋ณด์ด๋Š” ๋ฐ˜๋ฉด, ํšก๋ณด๊ฐ•๊ทผ๋น„๊ฐ€ ๋†’์€ ๊ฒฝ์šฐ์—์„œ๋Š” ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๋ณด๋‹ค ๋” ๋†’์€ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ๋ฉด๋‚ด์ „๋‹จ๊ฐ•๋„ ๋„๋‹ฌ ์‹œ์˜ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์—์„œ๋„ ์ด์™€ ์œ ์‚ฌํ•œ ๊ฒฝํ–ฅ์ด ๋ณด์ด๋ฉฐ, ๋‚ฎ์€ ๋ณด๊ฐ•๊ทผ๋น„์—์„œ๋Š” ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ ๋” ํฐ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ๋‚˜ํƒ€๋‚ด๋ฉฐ, ๋†’์€ ๋ณด๊ฐ•๊ทผ๋น„์—์„œ๋Š” CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ ์ข€ ๋” ํฐ ์ „๋‹จ๋ณ€ํ˜•๋ฅ  ๊ฐ’์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ์ด์™€ ๊ฐ™์€ ๊ฒฐ๊ณผ๋Š” Fig. 8๊ณผ Fig. 9๋กœ ๋‚˜ํƒ€๋‚ธ ๊ฐ๊ธฐ ๋‹ค๋ฅธ ํšก๋ณด๊ฐ•๊ทผ๋น„๋ฅผ ๊ฐ€์ง„ ๋ฉค๋ธŒ๋ ˆ์ธ ์š”์†Œ์—์„œ ์ฒ ๊ทผ๊ณผ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์˜ ๋ฉด๋‚ด์ „๋‹จ๊ฐ•๋„์™€ ๊ทธ ๋•Œ์˜ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ์ง์ ‘ ๋น„๊ตํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋ณด๋ฉด ์‰ฝ๊ฒŒ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค. ๋ฉด๋‚ด์ „๋‹จ๊ฐ•๋„๋ฅผ ๋น„๊ตํ•œ Fig. 8์—์„œ ํšก๋ณด๊ฐ•๊ทผ๋น„๊ฐ€ 2.98%์ผ ๋•Œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” ์ „๋‹จ๊ฐ•๋„๊ฐ€ 12.52MPa์ธ๋ฐ ๋น„ํ•ด CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” 11.09MPa๋กœ ์ „๋‹จ๊ฐ•๋„๊ฐ€ 10% ๋„˜๊ฒŒ ์ €ํ•˜๋˜๋Š” ๊ฒƒ์„ ๋ณผ ์ˆ˜ ์žˆ์œผ๋ฉฐ, ๋ฐ˜๋ฉด์— ํšก๋ณด๊ฐ•๊ทผ๋น„๊ฐ€ 0.33%๋กœ ์ž‘์„ ๋•Œ์—๋Š” ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” ์ „๋‹จ๊ฐ•๋„๊ฐ€ 4.17MPa์ธ ๊ฒƒ์— ๋น„ํ•ด CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” 6.86MPa๋กœ ์ „๋‹จ๊ฐ•๋„๊ฐ€ 60% ๋„˜๊ฒŒ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค. Fig. 9๋Š” ์ตœ๋Œ€ ์ „๋‹จ์‘๋ ฅ์—์„œ์˜ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ๋น„๊ตํ•˜์—ฌ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์œผ๋กœ, ํšก๋ณด๊ฐ•๊ทผ๋น„๊ฐ€ 2.98%์ผ ๋•Œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์ด 0.0074์ธ๋ฐ ๋ฐ˜ํ•ด CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” 0.0088๋กœ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์ด 20%์— ๊ฐ€๊นŒ์ด ์ฆ๊ฐ€๋œ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋Š” ๋ฐ˜๋ฉด์—, ํšก๋ณด๊ฐ•๊ทผ๋น„ 0.33%์ผ ๋•Œ์—๋Š” ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์™€ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์˜ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์ด ๊ฐ๊ฐ 0.0146, 0.0137๋กœ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ 6% ์ •๋„ ๋” ์ž‘๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด์™€ ๊ฐ™์€ ๊ฒฐ๊ณผ๋Š” ์ฒ ๊ทผ์— ๋น„ํ•ด ์ƒ๋Œ€์ ์œผ๋กœ ์ž‘์€ ๊ฐ’์˜ CFRP ๋ณด๊ฐ•๊ทผ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋กœ ์ธํ•œ ๊ฒƒ์ด๋‹ค.

Fig. 7 In-plane shear stress-strain behaviors obtained from MCFT analysis
../../Resources/ksm/jksmi.2024.28.4.13/fig7.png
Fig. 8 Comparison of in-plane shear strengths for steel and CFRP reinforced members for different transverse reinforcement
../../Resources/ksm/jksmi.2024.28.4.13/fig8.png
Fig. 9 Comparison of in-plane shear strengths for steel and CFRP reinforced members for different transverse reinforcement
../../Resources/ksm/jksmi.2024.28.4.13/fig9.png

Fig. 10์—์„œ๋Š” ํšก๋ณด๊ฐ•๊ทผ๋น„($\rho_{y}$)๊ฐ€ 0.33%์ผ ๋•Œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋Œ€ํ•ด ์ข…๋ฐฉํ–ฅ ๋ฐ ํšก๋ฐฉํ–ฅ ์ฒ ๊ทผ์˜ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ($\epsilon_{x}$ ๋ฐ $\epsilon_{y}$)์„ Fig. 10(a)์™€ (b)๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, ์ฝ˜ํฌ๋ฆฌํŠธ์— ์ž‘์šฉํ•˜๋Š” ์••์ถ• ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ ($f_{c2}-\epsilon_{2}$) ๊ณก์„ ์„ ๋ณ€ํ˜•๋ฅ  ํ•จ์ˆ˜๋กœ ๊ตฌํ•ด์ง€๋Š” ์••์ถ•๊ฐ•๋„ ๊ณก์„ ๊ณผ ํ•จ๊ป˜ Fig. 10(c)๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๊ทธ๋ฆฌ๊ณ  ํšก๋ณด๊ฐ•๊ทผ๋น„($\rho_{y}$)๊ฐ€ 0.33%์ผ ๋•Œ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ๋ณด๊ฐ•๊ทผ์˜ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ($\epsilon_{x}$ ๋ฐ $\epsilon_{y}$), ๊ทธ๋ฆฌ๊ณ  $f_{c2}-\epsilon_{2}$ ๊ณก์„ ์„ Fig. 11(a)-(c)๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. $\rho_{y}$=0.33%์—์„œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” ์ข…๋ฐฉํ–ฅ ์ฒ ๊ทผ์€ ํŒŒ๊ดด๋  ๋•Œ๊นŒ์ง€ ํ•ญ๋ณต์— ๋„๋‹ฌํ•˜์ง€ ์•Š์œผ๋ฉฐ ํšก๋ฐฉํ–ฅ ์ฒ ๊ทผ์ด ๋จผ์ € ํ•ญ๋ณตํ•œ ์ดํ›„์— ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•์‘๋ ฅ์ด ๋ณ€ํ˜•๋ฅ ์˜ ํ•จ์ˆ˜๋กœ ์ œ์‹œ๋˜๋Š” ์••์ถ•๊ฐ•๋„์— ๋„๋‹ฌํ•˜์—ฌ ํŒŒ๊ดด๋  ๋•Œ๊นŒ์ง€ ํฐ ๋ณ€ํ˜•๋ฅ  ์ฆ๊ฐ€๋ฅผ ๋ณด์ด๊ณ  ์žˆ๋‹ค. Fig. 10(c)์—์„œ ๋ณด๋Š” ๋ฐ”์™€ ๊ฐ™์ด, ์••์ถ•๊ฐ•๋„๋Š” ์•ฝ 10.9MPa์„ ๋‚˜ํƒ€๋‚ด๊ณ  ๊ทธ ๋•Œ์˜ ์••์ถ•๋ณ€ํ˜•๋ฅ ์€ ์•ฝ 0.0017์ด๋‹ค. ํ•œํŽธ Fig. 11์— ๋‚˜ํƒ€๋‚ธ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” ์ข…๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ ๋ฐ ํšก๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ ๋ชจ๋‘ ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ๊นŒ์ง€ ๋„๋‹ฌํ•˜์ง€ ์•Š์œผ๋ฉฐ, ํŒŒ๊ดด์‹œ ํšก๋ฐฉํ–ฅ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์ด ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋น„ํ•ด ํ›จ์”ฌ ์ž‘๊ฒŒ ๋‚˜ํƒ€๋‚œ๋‹ค. ์ด๋Ÿฌํ•œ ์ฐจ์ด๋กœ ์ธํ•ด์„œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋” ํฐ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ๋‚˜ํƒ€๋‚ด๋ฉฐ, ์ด์™€ ๊ฐ™์€ ๊ฒฐ๊ณผ๋Š” ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์— ๊ด€ํ•œ ์‹ (4)-(6)์œผ๋กœ๋ถ€ํ„ฐ๋„ ํ™•์ธํ•  ์ˆ˜ ์žˆ์„ ๊ฒƒ์ด๋‹ค. ๋˜ํ•œ Fig. 11(c)์—์„œ๋Š” ์••์ถ•๊ฐ•๋„๊ฐ€ ์•ฝ 14.2MPa์ด๋ฉฐ ๊ทธ ๋•Œ์˜ ์••์ถ•๋ณ€ํ˜•๋ฅ ์€ 0.0019 ์ •๋„์ž„์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋Š”๋ฐ, ์‹ (3)์„ ๊ณ ๋ คํ•  ๋•Œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋น„ํ•ด ํ›จ์”ฌ ๋†’์€ ์••์ถ•๊ฐ•๋„๊ฐ€ ๊ฒฐ๊ตญ ์ƒ๋Œ€์ ์œผ๋กœ ๋†’์€ ๋ฉด๋‚ด์ „๋‹จ๊ฐ•๋„๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค๊ณ  ํŒ๋‹จํ•  ์ˆ˜ ์žˆ๋‹ค.

Fig. 12 ๋ฐ Fig. 13์€ ํšก๋ณด๊ฐ•๊ทผ๋น„($\rho_{y}$)๊ฐ€ 2.98%์ผ ๋•Œ์˜ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์™€ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ์ข…๋ฐฉํ–ฅ ๋ฐ ํšก๋ฐฉํ–ฅ ์ฒ ๊ทผ์˜ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ($\epsilon_{x}$ ๋ฐ $\epsilon_{y}$)๊ณผ ์ฝ˜ํฌ๋ฆฌํŠธ์— ์ž‘์šฉํ•˜๋Š” ์••์ถ• ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ ($f_{c2}-\epsilon_{2}$) ๊ณก์„ ์„ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค. ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ ํŒŒ๊ดด ์‹œ ์ข…๋ฐฉํ–ฅ ๋ฐ ํšก๋ฐฉํ–ฅ ์ฒ ๊ทผ์˜ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์€ 0.0019 ๋‚ด์™ธ๋กœ ๋ชจ๋‘ ํ•ญ๋ณต์ƒํƒœ์— ๋„๋‹ฌํ•˜์ง€ ์•Š์œผ๋ฉฐ, ์ฝ˜ํฌ๋ฆฌํŠธ ์••์ถ•๊ฐ•๋„๋Š” 24.3MPa, ๊ทธ ๋•Œ์˜ ์••์ถ•๋ณ€ํ˜•๋ฅ ์€ 0.0018 ์ •๋„์ด๋‹ค. CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—๋Š” ํŒŒ๊ดด ์‹œ ์ข…๋ฐฉํ–ฅ ๋ฐ ํšก๋ฐฉํ–ฅ ์ฒ ๊ทผ์˜ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์€ 0.0026 ๋‚ด์™ธ์ด๊ณ , ์ฝ˜ํฌ๋ฆฌํŠธ ์••์ถ•๊ฐ•๋„๋Š” 21.4MPa, ๊ทธ ๋•Œ์˜ ์••์ถ•๋ณ€ํ˜•๋ฅ ์€ 0.0018 ์ •๋„์ด๋‹ค. ์•ž์„œ ์„ค๋ช…ํ•œ ๊ฐ™์€ ๋ฐฉ์‹์œผ๋กœ, ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋น„ํ•ด CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—์„œ ๋” ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚œ $\epsilon_{x}$ ๋ฐ $\epsilon_{y}$๊ฐ€ ์‹ (4)-(6)์— ๊ทผ๊ฑฐํ•˜์—ฌ ๋†’์€ ์ „๋‹จ๋ณ€ํ˜•๋ฅ  ๊ฒฐ๊ณผ์™€ ๊ด€๋ จ์ด ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ์œผ๋ฉฐ, ์ƒ๋Œ€์ ์œผ๋กœ ๋‚ฎ์€ ํŒŒ๊ดด ์‹œ ์••์ถ•๊ฐ•๋„๋กœ๋ถ€ํ„ฐ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์—์„œ ์ƒ๋Œ€์ ์œผ๋กœ ๋‚ฎ์€ ๋ฉด๋‚ด์ „๋‹จ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋ƒ„์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค.

Fig. 10 Tensile strain of steel rebar in x- and y-dir., and $f_{c2}-\epsilon_{2}$ curve of concrete in steel reinforced member with $\rho_{y}$=0.33%
../../Resources/ksm/jksmi.2024.28.4.13/fig10.png
Fig. 11 Tensile strain of CFRP rebar in x- and y-dir., and $f_{c2}-\epsilon_{2}$ curve of concrete in CFRP reinforced member with $\rho_{y}$=0.33%
../../Resources/ksm/jksmi.2024.28.4.13/fig11.png
Fig. 12 Tensile strain of steel rebar in x- and y-dir., and $f_{c2}-\epsilon_{2}$ curve of concrete in steel reinforced member with $\rho_{y}$=2.98%
../../Resources/ksm/jksmi.2024.28.4.13/fig12.png
Fig. 13 Tensile strain of CFRP rebar in x- and y-dir., and $f_{c2}-\epsilon_{2}$ curve of concrete in CFRP reinforced member with $\rho_{y}$=2.98%
../../Resources/ksm/jksmi.2024.28.4.13/fig13.png

5. ๊ฒฐ ๋ก 

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ „๋‹จ๋ฒฝ๊ณผ ๊ฐ™์€ ๋ฉด๋‚ด ์ „๋‹จ์„ ๋ฐ›๋Š” ๊ฒฝ์šฐ์— ๋Œ€ํ•ด, CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฑฐ๋™ํŠน์„ฑ์„ MCFT ์ด๋ก ์— ๊ธฐ๋ฐ˜ํ•˜์—ฌ ํ‰๊ฐ€ํ•˜๊ณ , ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ๊ฒฝ์šฐ์™€ ๋น„๊ตํ•˜์—ฌ ๋ถ„์„ํ•˜๊ณ ์ž ํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ๋ฅผ ์š”์•ฝํ•˜์—ฌ ์ •๋ฆฌํ•˜๋ฉด ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

(1) ์ข…๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ๋น„๋ฅผ 2.96%๋กœ ์ผ์ •ํ•˜๊ฒŒ ํ•˜๊ณ , ํšก๋ฐฉํ–ฅ ๋ณด๊ฐ•๊ทผ๋น„๋ฅผ 0.30์—์„œ 2.98%๊นŒ์ง€ ๋ณ€ํ™”์‹œ์ผฐ์„ ๋•Œ, ์ฒ ๊ทผ ๋ฐ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ํŒจ๋„์˜ ๋ฉด๋‚ด ์ „๋‹จ๊ฑฐ๋™์„ MCFT์— ๊ธฐ๋ฐ˜ํ•œ ํ•ด์„์„ ํ†ตํ•ด ํ‰๊ฐ€ํ•˜์˜€๋‹ค.

(2) ๋ณด๊ฐ•๊ทผ๋น„ 0.30์—์„œ 1.19% ์‚ฌ์ด์—์„œ๋Š” CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๋ณด๋‹ค ๋†’์€ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋ณด์˜€์œผ๋ฉฐ, ๊ทธ ์ด์ƒ์˜ 1.79% ๋ฐ 2.98%์—์„œ๋Š” ์ƒ๋Œ€์ ์œผ๋กœ ๋‚ฎ์€ ์ „๋‹จ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

(3) ์ตœ๋Œ€์ „๋‹จ๋ณ€ํ˜•๋ฅ ์€ ๋‚ฎ์€ ๋ณด๊ฐ•๊ทผ๋น„์—์„œ ์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๊ฐ€ ๋” ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, 0.97% ์ด์ƒ์—์„œ๋Š” CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋” ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ ๋ณด๊ฐ•๊ทผ๋น„๊ฐ€ ์ปค์งˆ์ˆ˜๋ก ์ฒ ๊ทผ ๋Œ€๋น„ ์ „๋‹จ๋ณ€ํ˜•๋ฅ  ์ฆ๊ฐ€์œจ์ด ๋” ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

(4) ์ž‘์€ ๋ณด๊ฐ•๊ทผ๋น„ ๋ฒ”์œ„์—์„œ ํšก๋ณด๊ฐ•๊ทผ์˜ ๋ณ€ํ˜•์ด ํฌ๊ฒŒ ๋ฐœ์ƒํ•˜์˜€์„ ๋•Œ, CFRP ๋ณด๊ฐ•๊ทผ์—์„œ๋Š” ์ฒ ๊ทผ๊ณผ ๋‹ฌ๋ฆฌ ํ•ญ๋ณต ์—†์ด ํฐ ์‘๋ ฅ์ „๋‹ฌ์ด ๊ฐ€๋Šฅํ•˜์—ฌ ์ฃผ๋ณ€ํ˜•๋ฅ ์— ์˜์กด์ ์ธ ์••์ถ•๊ฐ•๋„๋ฅผ ๋†’๊ฒŒ ํ™•๋ณดํ•˜์—ฌ ์ „๋‹จ๊ฐ•๋„๊ฐ€ ๋†’๊ฒŒ ๋‚˜ํƒ€๋‚œ ๋ฐ˜๋ฉด, ์ฒ ๊ทผ์€ ํ•ญ๋ณต ์ดํ›„ ํฐ ๋ณ€ํ˜•๋ฅ ์„ ๋™๋ฐ˜ํ•˜์—ฌ ์ฒ ๊ทผ ๋Œ€๋น„ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋” ํฐ ์ „๋‹จ๊ฐ•๋„ ๋ฐ ์ž‘์€ ์ตœ๋Œ€์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ๋ณด์ด๋Š” ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ์—ˆ๋‹ค.

(5) ๋†’์€ ๋ณด๊ฐ•๊ทผ๋น„ ๋ฒ”์œ„์—์„œ๋Š” ์ฒ ๊ทผ์˜ ํ•ญ๋ณต์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š์œผ๋ฉฐ ์ฒ ๊ทผ์— ๋น„ํ•ด ์ž‘์€ CFRP ๋ณด๊ฐ•๊ทผ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋กœ ์ธํ•˜์—ฌ ๋ณด๊ฐ•๊ทผ์—์„œ์˜ ํฐ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์ด ๋ฐœ์ƒํ•˜๊ฒŒ ๋˜์–ด ์ฒ ๊ทผ ๋Œ€๋น„ CFRP ๋ณด๊ฐ•๊ทผ์„ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ์— ๋” ์ž‘์€ ์ „๋‹จ๊ฐ•๋„ ๋ฐ ํฐ ์ „๋‹จ๋ณ€ํ˜•๋ฅ ์„ ๋ณด์ด๋Š” ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ์—ˆ๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

์ด ์—ฐ๊ตฌ๋Š” ๊ตญํ† ๊ตํ†ต๋ถ€/๊ตญํ† ๊ตํ†ต๊ณผํ•™๊ธฐ์ˆ ์ง„ํฅ์›์˜ ์ง€์›์œผ๋กœ ์ˆ˜ํ–‰๋˜์—ˆ์Œ(๊ณผ์ œ๋ฒˆํ˜ธ RS-2021-KA163381).

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