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์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ, ์ถ• ๊ตฌ์†, ํ™”์žฌ, ํ˜„์ˆ˜์ž‘์šฉ, ์—ด ํ•ด์„
reinforced concrete structure, axial restraints, fire, catenary action, thermal analysis

  • 1. ์„œ ๋ก 

  •   1.1 R.C ๊ตฌ์กฐ๋ฌผ์˜ ๊ฐ•๊ฑด์„ฑ

  •   1.2 R.C ๊ตฌ์กฐ๋ฌผ์˜ ๊ฑฐ๋™์— ๋Œ€ํ•œ ๊ธฐ์กด ์—ฐ๊ตฌ

  • 2. ํ˜„์ˆ˜์ž‘์šฉ(catenary action)์˜ ๊ฑฐ๋™

  • 3. FEMํ•ด์„์„ ์œ„ํ•œ R.C๋ณด ๋ชจ๋ธ๋ง๊ณผ ๋ณ€์ˆ˜ ์—ฐ๊ตฌ

  •   3.1 R.C๋ณด ๋ชจ๋ธ๋ง(DIANA)

  •   3.2 ์—ด ํ•ด์„

  •   3.3 ๋ณ€์ˆ˜์— ์˜ํ•œ ๊ฒฐ๊ณผ

  •   3.3.1 ์ฒ ๊ทผ์˜ ๋ฉด์ 

  •   3.3.2 ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ

  •   3.3.3 ๊ฒฝ๊ฐ„/ํญ ๋น„

  •   3.3.4 ํ•˜์ค‘๋น„

  •   3.3.5 ํ”ผ๋ณต๋‘๊ป˜์˜ ์˜ํ–ฅ

  •   3.3.6 ์ถ• ๊ตฌ์† ์ •๋„

  • 4. ๊ฒ€์ฆ๊ณผ์ •

  • 5. ๊ฒฐ ๋ก 

1. ์„œ    ๋ก 

R.C ๊ตฌ์กฐ๋ฌผ์€ ๋‚ฎ์€ ์—ด ์ „๋„์œจ ๋•Œ๋ฌธ์—, ์—ด์˜ ์ƒ์Šน์†๋„๊ฐ€ ๋‚ฎ๊ณ  ๋ถˆ์— ์ž˜ ํƒ€์ง€ ์•Š๋Š” ์„ฑ์งˆ๋กœ ์ธํ•˜์—ฌ ๋†’์€ ๋‚ดํ™”์„ฑ๋Šฅ์„ ๊ฐ€์ง„ ๊ตฌ์กฐ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค(Yi et al. 2012; Choi et al. 2017). ์˜ˆ๋ฅผ ๋“ค์–ด R.C ์Šฌ๋ž˜๋ธŒ(300 mm)์˜ ๊ฒฝ์šฐ, ๋‚ดํ™”์„ฑ๋Šฅ์€ 2์‹œ๊ฐ„(ํ•œ๊ณ„์˜จ๋„๋ฅผ 500 ยฐC๋กœ ์ ์šฉ)์„ ์‰ฝ๊ฒŒ ์ถฉ์กฑ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค(Denoel 2007).

Fig. 1์€ ํ™”์žฌ ์‹œ ์ถ• ๊ตฌ์† ์—ฌ๋ถ€์— ๋”ฐ๋ฅธ ์ฒ ๊ณจ ๋ณด์˜ ๊ฑฐ๋™์„ ๋ณด์—ฌ์ฃผ์ง€๋งŒ, R.C๋ณด์˜ ๊ฑฐ๋™์—๋„ ์ ์šฉ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค. ๊ทธ ๊ฑฐ๋™์€ 3๋‹จ๊ณ„๋กœ ํ‘œํ˜„๋  ์ˆ˜ ์žˆ๋‹ค. ์ฒซ์งธ, ์—ดํŒฝ์ฐฝ์œผ๋กœ ์ธํ•˜์—ฌ ๋ณด ๋‹จ๋ถ€์— ์ถ• ์••์ถ•๋ ฅ์ด ๋ฐœ์ƒํ•˜๊ฒŒ ๋˜๊ณ , ์ด ํž˜์€ ๋ณด์˜ ์ตœ๋Œ€ ํœจ ๋Šฅ๋ ฅ์— ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€ ๊ณ„์† ์ƒ์Šนํ•œ๋‹ค. ์ด๋•Œ ์ถ• ์••์ถ•๋ ฅ๊ณผ ํœจ์€ ๋™์‹œ์— ๋ฐœ์ƒํ•œ๋‹ค. ๋‘˜์งธ, ๊ทธ ๋’ค ์••์ถ•๋ ฅ์€ ์ ์  ์ค„์–ด๋“ค๊ฒŒ ๋˜๊ณ , ๊ทธ ํž˜์˜ ํฌ๊ธฐ๊ฐ€ 0์— ๋„๋‹ฌํ•  ๋•Œ, ์ ์šฉํ•˜์ค‘์€ ๋ณด์˜ ํœจ ์„ฑ๋Šฅ์— ์˜ํ•ด ์ง€์ง€๋˜๊ฒŒ ๋˜๋ฉฐ ์ด ํ›„ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€๋ถ„์€ ๊ตฌ์กฐ์  ๋Šฅ๋ ฅ์„ ์ƒ์‹คํ•˜๊ฒŒ ๋œ๋‹ค. ์ด ๋•Œ ์ถ• ๋ณ€ํ˜•์œผ๋กœ ์ธํ•œ ๋ณด์˜ ์ˆ˜์ถ•์ด ๋ณด์˜ ํŒฝ์ฐฝ๊ณผ ๊ฐ™๋‹ค๋Š” ๊ฒƒ์„ ์„ค๋ช…ํ•  ์ˆ˜ ์žˆ๋‹ค. ์…‹์งธ ๊ทธ ๋’ค ์ถ•๋ ฅ์€ ์ธ์žฅ๋ ฅ์œผ๋กœ ๋ณ€ํ™”ํ•˜๊ฒŒ ๋œ๋‹ค. ๋‹จ์ˆœ์ง€์ง€์ผ ๊ฒฝ์šฐ์—, ์ถ•๋ ฅ์€ ์กด์žฌํ•˜์ง€ ์•Š๊ณ  ์ฃผ์œ„ ๊ตฌ์กฐ๋ฌผ ์‚ฌ์ด์— ๋ฐœ์ƒํ•˜๋Š” ์ƒํ˜ธ๊ฑฐ๋™ ๋˜ํ•œ ๋ฐœ์ƒํ•˜์ง€ ์•Š์œผ๋ฉฐ, ์ด๋•Œ ๋ณด๋Š” ์†Œ์„ฑ ํžŒ์ง€๊ฐ€ ๋ฐœ์ƒํ•˜๊ณ  runaway deflection์„ ๋ณด์ด๋ฉฐ ํŒŒ๊ดด๋œ๋‹ค(Fig. 1(b)).

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F1.jpg

Fig. 1

The behavior of an axially restrained beam and an unrestrained beam in fire

1.1 R.C ๊ตฌ์กฐ๋ฌผ์˜ ๊ฐ•๊ฑด์„ฑ

1968๋…„ ํ”„๋ฆฌ์ผ€์ŠคํŠธ ๋ฒฝ๊ณผ ๋ฐ”๋‹ฅ์œผ๋กœ ๊ตฌ์„ฑ๋œ ๋กœ๋‚œ ํฌ์ธํŠธ ๋นŒ๋”ฉ(Fig. 2)์€ ๊ฐ€์Šคํญ๋ฐœ๋กœ ์ธํ•ด ๊ฑด๋ฌผ ํ•œ์ชฝ์ด ํŒŒ๊ดด๋˜๋ฉด์„œ ๋ถ•๊ดด๋˜์—ˆ๋‹ค. ๋Œ€์ฒด ํ•˜์ค‘๊ฒฝ๋กœ์˜ ๋ถ€์กฑ์œผ๋กœ ์ธํ•˜์—ฌ, ์•„ํŒŒํŠธ์˜ ์ง€์ง€๊ฐ€ ๋ฌด๋„ˆ์ ธ์„œ ๊ตฌ์กฐ๋ฌผ์˜ ์—ฐ์‡„๋ถ•๊ดด๋ฅผ ์ผ์œผ์ผฐ๋‹ค. ์ด ์‚ฌ๊ฑด์€ ๋ถˆ๊ท ํ˜• ๋ถ•๊ดด๋ฅผ ๋‹ค๋ฃฐ ์‚ฌ์–‘์ ์ธ ๊ทœ์ •์„ ์ตœ์ดˆ๋กœ ์ˆ˜๋ฆฝํ•˜๊ฒŒ ๋œ ๊ณ„๊ธฐ๊ฐ€ ๋˜์—ˆ๋‹ค(Moore 2002). ๋˜ํ•œ ์ด ์‚ฌ๊ฑด์€ Basic building code (1993), ASCE(1994), ACI Committee 318(2002)์™€ ๊ฐ™์€ ๋‹ค๋ฅธ ์„ค๊ณ„์ฝ”๋“œ์— ์˜ํ–ฅ์„ ๋ผ์ณค๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F2.jpg >

Fig. 2

Ronan point collapse (Pearson and Delatte 2005)

๊ตฌ์กฐ์ ์ธ ๊ฐ•๊ฑด์„ฑ์€ ์•Œ๋ ค์ง€์ง€ ์•Š์€ ํ•˜์ค‘์กฐ๊ฑดํ•˜์—์„œ ๊ตฌ์กฐ๋ฌผ์˜ ๋ฐ˜์‘์„ ๋‹ค๋ฃจ์ง€๋งŒ, ์—ฌ์ „ํžˆ ๊ตฌ์กฐ์  ๊ฐ•๊ฑด์„ฑ์„ ์ˆ˜์น˜์ ์œผ๋กœ ์ •๋Ÿ‰ํ™” ํ•  ์ˆ˜ ์žˆ๋Š” ๋ฐฉ๋ฒ•์€ ์กด์žฌํ•˜์ง€ ์•Š๋Š”๋‹ค. ์—ฐ์‡„๋ถ•๊ดด์™€ ๋ถˆ๊ท ํ˜•๋ถ•๊ดด๋ฅผ ์ œ์–ดํ•˜๊ธฐ ์œ„ํ•œ ์ผ๋ฐ˜์ ์ธ ๋ฐฉ๋ฒ•์œผ๋กœ๋Š” ์ถฉ๊ฒฉ, ํญ๋ฐœ ๊ทธ๋ฆฌ๊ณ  ํ™”์žฌํ•˜์ค‘์œผ๋กœ ์ธํ•ด ์ค‘์š”ํ•œ ๊ตฌ์กฐ๋ถ€์žฌ๊ฐ€ ์ดˆ๊ธฐ์— ํŒŒ๊ดด๋˜์—ˆ๋‹ค๊ณ  ๊ฐ€์ •ํ•˜๊ณ  ๊ตฌ์กฐ๋ฌผ์ด ๋ถˆ๊ท ํ˜• ๋ถ•๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์ง€ ์•Š๊ฒŒ ํ•˜๋Š” ๊ฒƒ์ด๋‹ค. ๋”ฐ๋ผ์„œ ๊ธฐ๋‘ฅ๊ณผ ๊ฐ™์€ ๊ตฌ์กฐ์  ๋ถ€์žฌ๋ฅผ ์ œ๊ฑฐํ•œ ๋’ค, ๊ตฌ์กฐ๋ฌผ์˜ ๊ฑฐ๋™์„ ์‚ดํ”ผ๋Š” ๋ฐฉ๋ฒ•์ด ๊ตฌ์กฐ์  ๊ฐ•๊ฑด์„ฑ์„ ํ‰๊ฐ€ํ•˜๋Š” ์ผ๋ฐ˜์ ์ธ ๋ฐฉ๋ฒ•์ด ๋˜์—ˆ๋‹ค(Wang 2003).

1.2 R.C ๊ตฌ์กฐ๋ฌผ์˜ ๊ฑฐ๋™์— ๋Œ€ํ•œ ๊ธฐ์กด ์—ฐ๊ตฌ

์ถ• ๊ตฌ์†์„ ๊ฐ€์ง„ ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ ๊ฑฐ๋™์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋Š” ์ƒ์˜จ๊ณผ ํ™”์žฌ๊ฐ€ ๋ฐœ์ƒํ–ˆ์„ ๋•Œ๋กœ ๋‚˜๋ˆŒ ์ˆ˜ ์žˆ๋‹ค. ์ƒ์˜จ์—์„œ๋Š” ๋งŽ์€ ์‹คํ—˜-ํ•ด์„์ ์ธ ์—ฐ๊ตฌ๊ฐ€ ์ด๋ฃจ์–ด ์ ธ์žˆ๋Š” ๋ฐ˜๋ฉด์— ํ™”์žฌ๊ฐ€ ๋ฐœ์ƒํ–ˆ์„ ๋•Œ์˜ ์—ฐ๊ตฌ๋Š” ๊ฑฐ์˜ ์ด๋ฃจ์–ด ์ง€์ง€ ์•Š์€ ์‹ค์ •์ด๋‹ค. Sasani and Kropelnicki(2008)๋Š” ์ƒ์˜จ์—์„œ 7์ธต์งœ๋ฆฌ R.C ๊ตฌ์กฐ๋ฌผ์˜ ๊ฑฐ๋™์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•ด ๊ธฐ๋‘ฅ์ด ํŒŒ๊ดด๋˜์—ˆ์„ ๋•Œ์˜ ์ƒํ™ฉ์„ ๊ฐ€์ •ํ•˜์—ฌ ์‹คํ—˜์  ์—ฐ๊ตฌ์™€ FEM์ƒ์šฉํ”„๋กœ๊ทธ๋žจ์ธ Ansys๋ฅผ ์ด์šฉํ•œ ํ•ด์„์  ์—ฐ๊ตฌ๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค(Fig. 3). ๋ณด ํ•˜๋‹จ์˜ ์ฒ ๊ทผ์—์„œ ๋ถ€๋ถ„์ ์ธ ํŒŒ๋‹จ์ด ๋ฐœ์ƒํ–ˆ์Œ์—๋„ ๋ถˆ๊ตฌํ•˜๊ณ , ๋ณด๋Š” ํŒŒ๊ดด๋˜์ง€ ์•Š๊ณ  ์ถ”๊ฐ€์ ์ธ ๋ณ€ํ˜•์ด ๋ฐœ์ƒํ–ˆ๋‹ค(Sasani and Kropelnicki 2008). ์ดˆ๊ธฐ ์ˆ˜์น˜ํ•ด์„ ๋ชจ๋ธ์—์„œ๋Š” ํ˜„์ˆ˜์ž‘์šฉ์ด ๋ฐœ์ƒํ•˜๊ธฐ ์ „์— ๋ฉˆ์ถ”์—ˆ์œผ๋‚˜ ๊ทธ ํ›„ ๋ชจ๋ธ์—์„œ๋Š” ํ˜„์ˆ˜์ž‘์šฉ์— ๋Œ€ํ•œ ์‹คํ—˜๊ฐ’๊ณผ ์ž˜ ์ผ์น˜ํ•˜์˜€๋‹ค(Fig. 3(b)).

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F3.jpg

Fig. 3

Description of plan and comparison of test and simulation results for a R.C frame under column removal (Sasani and Kropelnicki 2008)

The National Institute of Standard and Technology(NIST)์—์„œ R.C๊ตฌ์กฐ๋ฌผ์ด ๋ถ•๊ดดํ•  ๋•Œ๊นŒ์ง€ ํ˜„์ˆ˜์ž‘์šฉ์„ ๊ณ ๋ คํ•œ ์‹คํ—˜์ด ์ด๋ฃจ์–ด์กŒ๋‹ค(Lew et al. 2011). ์ด ์‹คํ—˜์˜ ๋ชฉ์ ์€ ์ฒซ์งธ ๊ธฐ๋‘ฅ์ด ํŒŒ๊ดด๋œ ์‹œ๋‚˜๋ฆฌ์˜ค์—์„œ R.C ๊ตฌ์กฐ๋ฌผ์˜ ๊ฑฐ๋™๊ณผ ์ˆ˜์น˜ํ•ด์„๊ฒ€์ฆ์„ ์œ„ํ•œ ์‹คํ—˜ ๋ฐ์ดํ„ฐ์˜ ํš๋“์ด๋‹ค. ์ˆ˜์น˜ํ•ด์„๊ฒ€์ฆ์„ ์œ„ํ•ด LS โ€“ DYNA(Hallquist 2007)๊ฐ€ ์ด์šฉ๋˜์—ˆ๊ณ  ์‹คํ—˜๊ฒฐ๊ณผ๋Š” ์ถ• ๊ตฌ์†์„ ๊ฐ€์ง„ R.C๋ณด๊ฐ€ ์„œ๋ก ์—์„œ ์–ธ๊ธ‰๋œ 3๋‹จ๊ณ„์˜ ๊ฑฐ๋™์„ ๋ณด์—ฌ์ค€๋‹ค(Fig. 4). Fig. 5๋Š” Yu and Tan(2013)์˜ ์‹คํ—˜์—ฐ๊ตฌ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ๊ฒฐ๋ก ์—์„œ ์ €์ž๋Š” โ€œflexural action develops until all plastic hinges occur.โ€๋ผ๊ณ  ์–ธ๊ธ‰ํ–ˆ๋‹ค. R.C๋ณด์˜ ํ˜„์ˆ˜์ž‘์šฉ์€ ์ถฉ๋ถ„ํ•œ ์ถ• ๊ตฌ์†๊ณผ ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ ๋•Œ๋ฌธ์— ๋ฐœ์ƒํ•˜๊ณ  ์ธ์žฅ์ฒ ๊ทผ์ด ํŒŒ๋‹จ ๋  ๋•Œ๊นŒ์ง€ ์—ฐ์†๋œ๋‹ค. ์ถ• ๊ตฌ์†์„ ๋ฐ›๋Š” R.C๋ณด์— ํ™”์žฌ๊ฐ€ ๋ฐœ์ƒํ–ˆ์„ ๋•Œ์˜ ์—ฐ๊ตฌ๋Š” ๋งค์šฐ ์ ์€ ๊ฐ€์šด๋ฐ Dwaikat and Kodur (2009)๋Š” 6๊ฐœ์˜ R.C๋ณด๋กœ ๋‚ดํ™”์„ฑ๋Šฅ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ–ˆ๋‹ค. ์‹คํ—˜๊ฒฐ๊ณผ๋Š” Fig. 6๊ณผ ๊ฐ™๋‹ค. B1, B3, B5 ์‹คํ—˜์ฒด๋Š” ์ถ• ๊ตฌ์†์ด ์—†์—ˆ๊ธฐ ๋•Œ๋ฌธ์— โ€œrun-awayโ€ ํ˜„์ƒ์ด ๋‚˜ํƒ€๋‚ฌ๋‹ค. B2์™€ B6๋Š” ์ถ• ๊ตฌ์†์ด ์žˆ์—ˆ์ง€๋งŒ low fire load(LF - natural fire curve)๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ํ™”์žฌ์— ๋Œ€ํ•œ ๋…ธ์ถœ์ด ์ถฉ๋ถ„์น˜ ์•Š์•„์„œ ํŒŒ๊ดด๋ชจ๋“œ๋กœ ๋„๋‹ฌํ•˜์ง€ ๋ชปํ–ˆ๊ธฐ ๋•Œ๋ฌธ์— ํ˜„์ˆ˜์ž‘์šฉ์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š์•˜๋‹ค. ๊ฒฐ๋ก ์ ์œผ๋กœ Dwaikat and Kodur๋Š” โ€œload level and axial restraint have significant influence on the fire response of R.C beamsโ€๋ผ๊ณ  ์–ธ๊ธ‰ํ–ˆ๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F4.jpg

Fig. 4

Outputs of test results and simulation results (Lew et al. 2011)

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Fig. 5

Failure mode & axial reaction force vs vertical force relationships (Yu and Tan 2013)

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F6.jpg

Fig. 6

Test and midspan deflection โ€“ time relationships for the tested R.C beams (Dwaikat and Kodur 2009)

2. ํ˜„์ˆ˜์ž‘์šฉ(catenary action)์˜ ๊ฑฐ๋™

Fig. 7์—์„œ์ฒ˜๋Ÿผ, R.C๋ณด ๋‹จ๋ถ€์— ์ถ• ๊ตฌ์†์ด ์ ์šฉ๋˜๋Š” ๊ฒฝ์šฐ, ์ถ• ๋ฐ˜๋ ฅ๊ณผ ์ ์šฉํ•˜์ค‘, ๊ทธ๋ฆฌ๊ณ  ์ˆ˜์ง์ฒ˜์ง์— ์˜ํ•ด Fig. 8๊ณผ ๊ฐ™์€ ๊ฑฐ๋™์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์ดˆ๊ธฐ์—๋Š” compressive arch action์ด ๋ณด์˜ ํœจ์— ๋Œ€ํ•ด ์ €ํ•ญํ•˜๊ณ  ์ถ• ์••์ถ•๋ ฅ๊ณผ ํœจ ๋ชจ๋ฉ˜ํŠธ๊ฐ€ ๋ฐœ์ƒํ•œ๋‹ค. ์ด ์ž‘์šฉ์€ ๋ณด๊ฐ€ ํ•˜์ค‘์ง€์ง€๋ ฅ์„ ์ƒ์‹คํ•  ๋•Œ๊นŒ์ง€ ํœจ๊ณผ ์••์ถ•๋ ฅ์ด ์กฐํ•ฉ๋˜๊ณ  ๊ณ„์†๋˜๋ฉฐ Fig. 8์˜ A์ ์„ ๊ฐ€๋ฆฌํ‚จ๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F7.jpg

Fig. 7

An axially restrained beam

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Fig. 8

General behavior of an axially restrained beam (Lee and Wang 2016)

์ดํ›„ ๋ณด๊ฐ€ equilibrium์— ๋„๋‹ฌํ•˜๊ธฐ ์œ„ํ•ด ์ฒ˜์ง์ด ์ฆ๊ฐ€ํ•˜๋ฉด์„œ ์••์ถ•๋ ฅ์€ ์ค„์–ด๋“ค๊ธฐ ๋•Œ๋ฌธ์— ์ ์šฉํ•˜์ค‘์€ ์ฆ๊ฐ€ํ•œ๋‹ค. ์ด ํ˜„์ƒ์€ ์••์ถ•๋ ฅ์ด ๊ฑฐ์˜ 0์— ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€ ๊ณ„์†๋˜๋ฉฐ Fig. 8์˜ B์ ๊ณผ ๊ฐ™๋‹ค. ์ด ๊ตฌ๊ฐ„์—์„œ๋Š” ์ถ•๋ ฅ์ด ์กด์žฌํ•˜์ง€ ์•Š๊ณ  ๋ณด๋Š” ์ˆœ์ˆ˜ ํœจ๋งŒ์„ ๋ฐ›๋Š”๋‹ค. ์ดํ›„์—๋„ ๋ณด๋Š” ํ˜„์ˆ˜์ž‘์šฉ(catenary action)์œผ๋กœ ์ธํ•˜์—ฌ ๊ณ„์†ํ•ด์„œ ํ•˜์ค‘์— ์ง€์ง€ํ•  ์ˆ˜ ์žˆ๊ฒŒ ๋œ๋‹ค. ์ด ๊ตฌ๊ฐ„์—์„œ ๋ณด์—๋Š” ์ธ์žฅ๋ ฅ์ด ๋ฐœ์ƒํ•˜๊ฒŒ ๋˜๋ฉฐ, ์ ์šฉํ•˜์ค‘์— ๋Œ€ํ•ญํ•˜์—ฌ ์ฒ ๊ทผ์— ์ธ์žฅ๋ ฅ์ด ๋ถ„๋ฐฐ๋œ๋‹ค. ๊ฒฐ๊ตญ ๋ณด๋Š” ์ธ์žฅ์ฒ ๊ทผ์˜ ํŒŒ๋‹จ์œผ๋กœ ํŒŒ๊ดด๋œ๋‹ค.

์ด ์—ฐ๊ตฌ์˜ ์ฃผ๋œ ๋ชฉ์ ์€ ์˜จ๋„๊ฐ€ ์ƒ์Šนํ•  ๋•Œ์˜ R.C๋ณด๊ฑฐ๋™์˜ ์ดํ•ด์— ์žˆ์œผ๋ฉฐ, ์ด๋ฅผ ์œ„ํ•ด Fig. 9์˜ B์—์„œ C ๊ตฌ๊ฐ„(ํ˜„์ˆ˜์ž‘์šฉ)์— ๋Œ€ํ•œ ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์ดํ•ดํ•˜๋Š” ๊ฒƒ์€ ๊ต‰์žฅํžˆ ์ค‘์š”ํ•˜๋‹ค. ํ˜„์ˆ˜์ž‘์šฉ์„ ์ƒ์„ธํ•˜๊ฒŒ ์ดํ•ดํ•˜๊ธฐ ์œ„ํ•ด ํ˜„์ˆ˜์ž‘์šฉ ์ „๋ฐ˜์— ๊ฑธ์นœ ์ˆ˜์น˜ํ•ด์„์— ๋Œ€ํ•œ ์—ฐ๊ตฌ ๋˜ํ•œ ํ•„์ˆ˜์ ์ด๋ฉฐ, ์ด์— ์„ ํ–‰ํ•˜์—ฌ ๋ณด ์ŠคํŒฌ์˜ ์ค‘์‹ฌ์— ์ง‘์ค‘ํ•˜์ค‘์ด ์ž‘์šฉํ•  ๋•Œ์˜ ๋ชจ๋ธ์„ ๊ณ ๋ คํ•ด์•ผ๋งŒ ํ•˜๊ณ , ํ‰ํ˜•, ํ˜ธํ™˜์„ฑ ๊ทธ๋ฆฌ๊ณ  ์ถ• ํŒฝ์ฐฝ์ด ๊ธฐ๋ณธ๊ฐœ๋…์ด ๋œ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์€ ์ฐจํ›„ ํ”„๋ ˆ์ž„๊ฑฐ๋™์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋ฅผ ์œ„ํ•ด ์‚ฌ์ „์— ๋ฐ˜๋“œ์‹œ ๊ฒ€ํ† ๋˜์–ด์•ผ ํ•  ์ถ• ๊ตฌ์†์„ ๊ฐ€์ง„ ๋ณด์—์„œ ํ™”์žฌ์— ๋…ธ์ถœ๋˜์—ˆ์„ ๋•Œ์˜ ํ˜„์ˆ˜์ž‘์šฉ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ์ฃผ๋ฅผ ์ด๋ฃจ๊ณ  ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ์ด๋ฒˆ ์—ฐ๊ตฌ๋Š” ์ถ• ๊ตฌ์†์„ ๊ฐ€์ง„ ๋ณด ๊ฑฐ๋™์˜ ์ดํ•ด์— ๊ทธ ์ดˆ์ ์ด ๋งž์ถ”์–ด์ ธ ์žˆ๊ณ , ์ด๋ฅผ ์œ„ํ•ด 3์žฅ์—์„œ๋Š” ์ˆ˜์น˜ํ•ด์„์„ ํ†ตํ•œ ๋ณ€์ˆ˜์—ฐ๊ตฌ์™€ ๊ทธ ์—ฐ๊ตฌ๋ฅผ ์œ„ํ•ด ํ•„์š”ํ•œ ์‚ฌํ•ญ๋“ค์— ๋Œ€ํ•ด ์„œ์ˆ ํ•  ๊ฒƒ์ด๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F9.jpg

Fig. 9

Axial reaction force and vertical deflection-time relationships of an axially restrained beam in fire (Lee and Wang 2016)

3. FEMํ•ด์„์„ ์œ„ํ•œ R.C๋ณด ๋ชจ๋ธ๋ง๊ณผ ๋ณ€์ˆ˜ ์—ฐ๊ตฌ

3.1 R.C๋ณด ๋ชจ๋ธ๋ง(DIANA)

๋ชจ๋“  ์ˆ˜์น˜ํ•ด์„์€ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฑฐ๋™์— ํŠนํ™”๋œ DIANAํ”„๋กœ๊ทธ๋žจ(Chan 1993)์„ ํ™œ์šฉํ•˜์—ฌ ํšจ์œจ์„ฑ์„ ๊ณ ๋ คํ•œ 2D ๋ชจ๋ธ์ด ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ํ˜„์ˆ˜์ž‘์šฉ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•ด ํ•ด์„์€ ๊ธฐํ•˜ํ•™์ , ์žฌ๋ฃŒ์ ์ธ ๋น„์„ ํ˜• ๋ชจ๋ธ์ด ์ด์šฉ๋˜์—ˆ๋‹ค. R.C๋ณด์˜ ๊ตฌ์กฐ์ ์ธ ๊ฑฐ๋™์„ ๋ชจ๋ธ๋ง ํ•˜๊ธฐ ์œ„ํ•ด ์ธ์žฅ๊ท ์—ด๊ฑฐ๋™์€ ๋งค์šฐ ์ค‘์š”ํ•˜๋ฏ€๋กœ, ๊ท ์—ด๊ฑฐ๋™์„ ๊ตฌํ˜„ํ•˜๊ธฐ ์œ„ํ•ด DIANA๋Š” discrete๊ท ์—ด(Moore 2002)๋ชจ๋ธ๊ณผ smeared๊ท ์—ด(Rashid 1968)๋ชจ๋ธ ๋‘ ๊ฐ€์ง€ ๋ฐฉ๋ฒ•์„ ์ œ์‹œํ•˜๊ณ  ์žˆ๋‹ค. Discrete๋ชจ๋ธ์€ ํฐ ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜๊ณ  ๊ทธ ์œ„์น˜๋ฅผ ์‚ฌ์ „์— ๋ฏธ๋ฆฌ ์•Œ ๋•Œ ์œ ๋ฆฌํ•œ ๋ชจ๋ธ(Ngo and Scordelis 1967)์ด๊ธฐ ๋•Œ๋ฌธ์— ์ด๋ฒˆ ์—ฐ๊ตฌ์—์„œ๋Š” ์ „์ฒด๋ชจ๋ธ๋ง์ด ๋ฉ”์‰ฌ์— ์ข…์†์ ์ด๊ณ , ์ ์ ˆํ•œ ๋ฉ”์‰ฌํฌ๊ธฐ ์‚ฐ์ •์ด ์ค‘์š”ํ•˜๋ฏ€๋กœ smeared๊ท ์—ด๋ชจ๋ธ์ด ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ๋˜ํ•œ smeared๊ท ์—ด๋ชจ๋ธ์€ ์••์ถ•๊ณผ ์ธ์žฅ๊ฑฐ๋™์—์„œ ๋ช‡๋ช‡์˜ ์†Œ์„ฑ๋ชจ๋ธ๊ณผ ๋™์‹œ์— ์ ์šฉ์ด ๊ฐ€๋Šฅํ•˜๋‹ค. ์••์ถ•๊ฑฐ๋™์—์„œ๋Š” Mohr- Coulomb์†Œ์„ฑ๋ชจ๋ธ์ด ์‚ฌ์šฉ๋˜์—ˆ์œผ๋ฉฐ, ์ธ์žฅ๊ฑฐ๋™์—์„œ๋Š” Hordijk tension softening์†Œ์„ฑ๋ชจ๋ธ์ด ํ•ด์„ ์‹œ ์ˆ˜๋ ด์„ฑ๊ณผ ์‹คํ—˜๊ฐ’๊ณผ์˜ ๊ฒ€์ฆ ์ธก๋ฉด์—์„œ ์ ์ ˆํ•˜๋‹ค๊ณ  ํŒ๋‹จ๋˜์–ด ์‚ฌ์šฉ๋˜์—ˆ๋‹ค(Lee and Wang 2016). ์ฒ ๊ทผ์˜ ๊ฒฝ์šฐ์—๋Š” Von Mises์†Œ์„ฑ๋ชจ๋ธ์ด ์ ์šฉ๋˜์—ˆ๋‹ค.

Fig. 10(b)๋Š” mesh sensitivity study๋ฅผ ์œ„ํ•œ ์„ธ ๊ฐœ์˜ ๋‹จ๋ฉด(200 mm ร— 200 mm, 300 mm ร— 300 mm, 400 mm ร— 400 mm, ๋ณด์˜ ์ŠคํŒฌ๊ธธ์ด ๊ฐ๊ฐ 3 m, 4.5 m, 6 m)์˜ ๋‹ค์–‘ํ•œ ๋ฉ”์‰ฌ ์‚ฌ์ด์ฆˆ(30 mm, 40 mm, 50 mm)์— ๋Œ€ํ•œ ์ˆ˜๋ ด์„ฑ์„ ๋น„๊ตํ•œ ๊ทธ๋ž˜ํ”„์ด๋ฉฐ, ๋ฉ”์‰ฌ ์‚ฌ์ด์ฆˆ 40 mm ร— 40 mm์—์„œ ์ˆ˜๋ ด์ด ๋˜์–ด ๊ทธ ์‚ฌ์ด์ฆˆ๊ฐ€ ์ด์šฉ๋˜์—ˆ๋‹ค. Fig. 11์€ 4์žฅ์—์„œ ์–ธ๊ธ‰๋œ ์‹คํ—˜๊ฒฐ๊ณผ(Yi et al. 2008)์™€ ๊ฐ ๋ฉ”์‰ฌ ์‚ฌ์ด์ฆˆ๊ฐ€ ๋‹ค๋ฅผ ๋•Œ์˜ ์ˆ˜์น˜ํ•ด์„ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•œ ๊ทธ๋ž˜ํ”„์ด๋‹ค. ์ด ๊ทธ๋ž˜ํ”„๋ฅผ ํ†ตํ•˜์—ฌ ๋ฉ”์‰ฌ ์‚ฌ์ด์ฆˆ 40 mm์ผ ๋•Œ์˜ ๊ฒฐ๊ณผ๊ฐ’์ด ์‹คํ—˜๊ฐ’๊ณผ ๊ฐ€์žฅ ์ž˜ ์ผ์น˜ํ•œ๋‹ค๋Š” ์‚ฌ์‹ค์„ ์•Œ ์ˆ˜ ์žˆ์—ˆ๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ๋Š” 4-node quadratic plane stress(Q8MEM)(Chan 1993)์š”์†Œ๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ๊ณ , ์ฒ ๊ทผ์€ embedded reinforcement(Chan 1993)์š”์†Œ๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ์œผ๋ฉฐ ์ฝ˜ํฌ๋ฆฌํŠธ์™€ ์™„์ „ํžˆ ๋ถ€์ฐฉ๋œ๋‹ค๊ณ  ๊ฐ€์ •ํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F10.jpg

Fig. 10

Summary of mesh sensitivity study results and final loads

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F11.jpg

Fig. 11

Comparison on experimental data and simulated data for mesh sensitivity study

3.2 ์—ด ํ•ด์„

๋ณด๋Š” ํ‘œ์ค€ํ™”์žฌ๊ณก์„  ASTM E119(American Society for Testing and Materials 2008)์— ๋…ธ์ถœ๋œ ๊ฒƒ์œผ๋กœ ๊ฐ€์ •ํ•˜์˜€๋‹ค. ์—ด ์ „๋‹ฌ ๋ชจ๋ธ๋ง์„ ์œ„ํ•ด Table 1์€ ์˜จ๋„๊ฐ€ ์ƒ์Šนํ•  ๋•Œ์˜ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์—ด ํŠน์„ฑ๊ณผ ๋ชจ๋ธ๋ง์— ํ•„์š”ํ•œ ๊ฒฝ๊ณ„์กฐ๊ฑด์„ ํ‘œํ˜„ํ•  ์ˆ˜ ์žˆ๋Š” ๋ฐ์ดํ„ฐ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค(Comite Europeen, 2002). ์ฒ ๊ทผ์˜ ์˜จ๋„์— ๊ด€ํ•ด์„œ๋Š” embedded ์š”์†Œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์— ๊ฐ™์€ ์œ„์น˜์— ์žˆ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์š”์†Œ์˜ ์˜จ๋„์™€ ๊ฐ™๋‹ค๊ณ  ๊ฐ€์ •๋˜๋ฏ€๋กœ ๋”ฐ๋กœ ํ‘œํ˜„๋˜์ง€๋Š” ์•Š์•˜๋‹ค(Chan 1993). ์ฒ ๊ณจ๊ณผ ๋‹ค๋ฅด๊ฒŒ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด ๋‹จ๋ฉด์˜ ์˜จ๋„๋Š” ๊นŠ์ด์— ๋”ฐ๋ผ ๋‹ค๋ฅด๋ฏ€๋กœ, ์—ด ์ „๋‹ฌ ํ•ด์„์—์„œ๋Š” general potential flowํ•ด์„์„ ๊ณ ๋ คํ•œ 2-node ๊ฒฝ๊ณ„์š”์†Œ์ธ heat flow element(B2HT)(Chan 1993)๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค(Fig. 12). ๋ณด ๋‹จ๋ถ€์—์„œ ์˜จ๋„์ฐจ์ด์— ๋Œ€ํ•œ ์˜ํ–ฅ์€ ๋ณด ๊ธธ์ด๋ฐฉํ–ฅ์˜ ๊ฑฐ๋™์— ์ง€๋ฐฐ์ ์ด๋ฏ€๋กœ ๋ฏธ๋น„ํ•˜๋‹ค๊ณ  ํ•  ์ˆ˜ ์žˆ๋‹ค(Lee and Wang 2016). ์ด ์—ฐ๊ตฌ์˜ ๋ชฉ์ ์€ ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์„ ์—ฐ์žฅ์‹œํ‚ค๊ธฐ ์œ„ํ•œ ๋‹ค์–‘ํ•œ ๋ณ€์ˆ˜์— ๋”ฐ๋ฅธ ์ˆ˜์น˜ํ•ด์„์ด๋ฏ€๋กœ, ์—ด์˜ ์žฌ๋ถ„๋ฐฐ๋Š” ๊ณ ๋ ค๋˜์ง€ ์•Š์•˜๋‹ค.

Thermal conductivity /Resources/kci/JKCI.2018.30.2.115/images/PICFF05.gif

/Resources/kci/JKCI.2018.30.2.115/images/PICFF06.gif (1)

Table 1 Thermal properties of concrete and boundary conditions for heat transfer (Comite Europeen, 2002)

/Resources/kci/JKCI.2018.30.2.115/images/Table_CONCRETE_30_2_01_T1.jpg
/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F12.jpg

Fig. 12

Fire exposure on 2-D heat transfer of the beam

์—ฌ๊ธฐ์„œ /Resources/kci/JKCI.2018.30.2.115/images/PICFF17.gif ์ฝ˜ํฌ๋ฆฌํŠธ์˜จ๋„(ยฐC), ์ฝ˜ํฌ๋ฆฌํŠธ์˜ specific heat๋Š” EN 1992-1-2:2002(Comite Europeen, 2002)๋ฅผ ์ด์šฉํ–ˆ์œผ๋ฉฐ, ์•„๋ž˜์˜ ์‹๊ณผ ๊ฐ™๋‹ค.

Cp(ฮธ)=900(J/kgK)for20ยฐCโ‰คฮธโ‰ค100ยฐC (2)

Cp(ฮธ)=900+(ฮธโ€“100)(J/kgK)for100ยฐCโ‰คฮธโ‰ค200ยฐC (3)

Cp(ฮธ)=1000+(ฮธโ€“200)/2(J/kgK)for200ยฐCโ‰คฮธโ‰ค400ยฐC (4)

Cp(ฮธ)=1100(J/kgK)for400ยฐCโ‰คฮธโ‰ค1200ยฐC (5)

DIANAํ”„๋กœ๊ทธ๋žจ๋‚ด์—์„œ ์—ด ํ•ด์„์€ ๋‹จ๋ฉด์— ๋Œ€ํ•œ ์˜จ๋„ ๊ฐ’์„ ๊ตฌํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์ˆ˜ํ–‰๋˜๋ฉฐ, 1์ฐจ์ ์œผ๋กœ ์—ด ํ•ด์„ ํ›„ ์˜จ๋„ ๊ฐ’์„ ์ด์šฉํ•˜์—ฌ 2์ฐจ์ ์œผ๋กœ ๊ตฌ์กฐํ•ด์„์ด ์ง„ํ–‰๋œ๋‹ค(Chan 1993). ๋ณธ ์—ฐ๊ตฌ์—์„œ ํ™”์žฌ๊ฐ€ ๋ฐœ์ƒํ–ˆ์„ ๋•Œ ๊ตฌ์กฐ๋ฌผ์˜ ์ƒ์กด์‹œ๊ฐ„์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•ด ๋ถ€์žฌ ๋‚ด์— ๊ฐ ์š”์†Œ ๋ณ„๋กœ ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ์˜จ๋„ ๊ฐ’์„ ์•Œ ์ˆ˜ ์žˆ๋Š” ์‹œ๊ฐ„์ด๋ ฅํ•ด์„์ด ๋ณ‘ํ–‰๋˜์—ˆ๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด ๋‹จ๋ฉด์˜ ์˜จ๋„๋Š” ๊นŠ์ด ๋ณ„๋กœ ๋งŽ์€ ์ฐจ์ด๋ฅผ ๋ณด์ด๋ฏ€๋กœ, ๊ฒฐ๊ณผ ๊ฐ’์ด ์˜จ๋„๊ฐ€ ์•„๋‹ˆ๋ผ ์‹œ๊ฐ„์˜ ํ•จ์ˆ˜๋กœ ๋˜์–ด์•ผ ํ•˜๋Š” ๊ฒƒ ๋˜ํ•œ ์‹œ๊ฐ„์ด๋ ฅํ•ด์„์ด ํ•„์š”ํ•œ ์ด์œ  ์ค‘์˜ ํ•˜๋‚˜์ด๋‹ค.

3.3 ๋ณ€์ˆ˜์— ์˜ํ•œ ๊ฒฐ๊ณผ

ํ™”์žฌ ์‹œ ์ถ• ๊ตฌ์†์„ ๋ฐ›๋Š” R.C๋ณด์˜ ๋‚ดํ™”์„ฑ๋Šฅ๊ณผ ๋‹ค์–‘ํ•œ ์„ค๊ณ„๋ณ€์ˆ˜๋“ค๊ณผ์˜ ๊ด€๊ณ„๋ฅผ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•ด, ๋ณ€์ˆ˜์—ฐ๊ตฌ๊ฐ€ ์ˆ˜ํ–‰๋˜์—ˆ๋‹ค. ์ฒ ๊ทผ์˜ ์ธ์žฅ๋ ฅ๊ณผ ๋ณด์˜ ํฐ ์ฒ˜์ง์ด ํ•„์ˆ˜์ ์ธ ํ˜„์ˆ˜์ž‘์šฉ์œผ๋กœ ์ธํ•˜์—ฌ ๋ณด์˜ ๋‚ดํ™”์„ฑ๋Šฅ์€ ํ–ฅ์ƒ๋  ์ˆ˜ ์žˆ๋‹ค.

๊ฐ ๋ณ€์ˆ˜๋“ค(์ฒ ๊ทผ๋ฉด์ , ์ฒ ๊ทผ์˜ ์‹ ์žฅ๋ ฅ, ๋ณด ๊ฒฝ๊ฐ„๊ณผ ๋‘๊ป˜์˜ ๋น„, ํ•˜์ค‘๋น„, ์ฒ ๊ทผ์˜ ์œ„์น˜, ์ถ• ๊ตฌ์† ์ •๋„)์€ Table 2์— ์ž˜ ๋‚˜ํƒ€๋‚˜ ์žˆ์œผ๋ฉฐ ๊ฒฝ๊ณ„์กฐ๊ฑด์€ ์ถ• ๊ตฌ์† ์ •๋„๋ฅผ ์ œ์™ธํ•œ ๋ชจ๋“  ๋ณ€์ˆ˜์˜ ๋‹จ๋ถ€ ๊ฒฝ๊ณ„์กฐ๊ฑด์€ Fig. 13(a)์™€ ๊ฐ™๊ณ  ๋˜ ๋‹ค๋ฅธ ๋ณ€์ˆ˜์ธ ์ถ• ๊ตฌ์† ์ •๋„๋ฅผ ๋„์‹ํ™”ํ•œ Fig. 13(b)๋กœ ๋‚˜๋ˆ„์–ด ์งˆ ์ˆ˜ ์žˆ์œผ๋ฉฐ, ํ•˜์ค‘์€ ๊ฒฝ๊ฐ„ ์ค‘์•™๋ถ€๋ถ„์— ์ง‘์ค‘ํ•˜์ค‘์œผ๋กœ ๊ฐ€์ •ํ•˜์˜€๋‹ค. ์‹ค์ œ ๊ตฌ์กฐ๋ฌผ์— ํ™”์žฌ๊ฐ€ ๋ฐœ์ƒํ•œ ์ƒํ™ฉ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•ด, ํ•˜์ค‘์€ ์ƒ์˜จ ์‹œ ๋ณด์˜ ๊ฒฝ๊ณ„์กฐ๊ฑด์ด ๋‹จ์ˆœ์ง€์ง€์ผ ๊ฒฝ์šฐ์— ํœจ ๋Šฅ๋ ฅ์„ 100 %๋กœ ๊ณ„์‚ฐํ•˜์—ฌ 70 %๋ฅผ ๊ณ ์ •ํ•˜์ค‘์œผ๋กœ ์žฌํ•˜๋˜๋ฉฐ, ํ™”์žฌํ•˜์ค‘์ด ์ฆ๊ฐ€๋˜๋Š” ๋ฐฉ์‹์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค.

Table 2 Input values for parametric study

/Resources/kci/JKCI.2018.30.2.115/images/Table_CONCRETE_30_2_01_T2.jpg
/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F13.jpg

Fig. 13

Boundary condition of axially restrained beams for simulation (unit: mm)

3.3.1 ์ฒ ๊ทผ์˜ ๋ฉด์ 

Fig. 14๋Š” ์ฒ ๊ทผ๋ฉด์ ์˜ ๋ณ€ํ™”์— ๋Œ€ํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ์ฒ ๊ทผ ๋ฉด์ ์ด ์ฆ๊ฐ€ํ•˜๋ฉด, ๋ณด์˜ ํœจ ์„ฑ๋Šฅ์€ ํ–ฅ์ƒ๋˜๊ณ  ๊ทธ ๊ฒฐ๊ณผ ๋‚ดํ™”์„ฑ๋Šฅ์€ ์ƒ์Šนํ•œ๋‹ค. ๊ณ ์˜จ์—์„œ ์ฒ ๊ทผ์˜ ๊ฐ•๋„๋Š” ๊ธ‰๊ฒฉํ•œ ๋ณ€ํ™”๋ฅผ ๊ฒช๊ธฐ ๋•Œ๋ฌธ์—, ๋ณด๊ฐ€ ํœจ ์„ฑ๋Šฅ์„ ์ƒ์‹คํ•  ๋•Œ(๋ณด์˜ ์ถ•๋ ฅ์ด 0์ด ๋˜๋Š” ๊ตฌ๊ฐ„) ์ฒ ๊ทผ ๋ฉด์ ์˜ ์ƒ์Šน์œผ๋กœ ์ธํ•œ ๋‚ดํ™”์„ฑ๋Šฅ์˜ ํ–ฅ์ƒ์€ ๋งค์šฐ ์ž‘๋‹ค. ์˜ˆ๋ฅผ ๋“ค์–ด ์ฒ ๊ทผ ๋‹จ๋ฉด์ ์ด 400 mm2์ด๋ฉด์„œ ํœจ ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ–ˆ์„ ๋•Œ, ์ฒ ๊ทผ์˜ ์˜จ๋„๋Š” 487.13 ยฐC ์ด๊ณ , ์ฒ ๊ทผ์˜ ์˜จ๋„์— ๋Œ€ํ•œ ๊ฐ์†Œ๊ณ„์ˆ˜๋Š” 0.725์ด๋‹ค. ์ฒ ๊ทผ์˜ ๋‹จ๋ฉด์ ์ด 50 % ์ƒ์Šน๋œ 600 mm2๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ์„ ๋•Œ, ์ฒ ๊ทผ์˜ ์˜จ๋„๋Š” 580.97 ยฐC์ด๋ฉฐ ๊ฐ์†Œ๊ณ„์ˆ˜๋Š” 0.538์ด๋‹ค. ๊ทธ๋Ÿผ์—๋„ ๋ถˆ๊ตฌํ•˜๊ณ  ์ฒ ๊ทผ์˜จ๋„์˜ ์ƒ์Šน๋น„์œจ์ด ๋‚ฎ์€ ๋•๋ถ„์—, ๋ณด์˜ ํœจ ์„ฑ๋Šฅ์ด ํ•œ๊ณ„์— ๋„๋‹ฌํ•˜๋Š” ์‹œ๊ฐ„์€ 71๋ถ„์—์„œ 109๋ถ„์œผ๋กœ ์ƒ์Šนํ–ˆ๋‹ค. ์ถ• ๊ตฌ์† ๋•๋ถ„์— ๋ณด๋Š” ํ™”์žฌ์— ๋…ธ์ถœ๋˜๋”๋ผ๋„ ํœจ ์„ฑ๋Šฅ์˜ ์ƒ์‹ค ํ›„์—๋„ ๊ธด ์‹œ๊ฐ„ ๋™์•ˆ ๋ถ•๊ดด๋˜์ง€ ์•Š๋Š”๋‹ค. ์˜ˆ๋ฅผ ๋“ค์–ด 400 mm2 ์ฒ ๊ทผ๋ฉด์ ์„ ๊ฐ€์ง„ ๋ณด์˜ ๋‚ดํ™”์„ฑ๋Šฅ์€ 214๋ถ„์ด๋ฉฐ, ํœจ ์„ฑ๋Šฅ์ด ๋‹คํ•˜๋Š” ์‹œ๊ฐ„์€ 71๋ถ„์ด๋‹ค. ์ฒ ๊ทผ์˜ ๋ฉด์ ์„ 600 mm2๋กœ ์ฆ๊ฐ€์‹œํ‚ค๋ฉด, ๋‚ดํ™”์„ฑ๋Šฅ์‹œ๊ฐ„์€ 250๋ถ„์œผ๋กœ ์ƒ์Šนํ•œ๋‹ค. ์ฒ ๊ทผ์˜ ๋ฉด์ ์ฆ๊ฐ€๋ฅผ ํ†ตํ•˜์—ฌ ์ธ์žฅ์„ฑ๋Šฅ์ด ์ƒ์Šน๋  ๋•Œ, ๋™์ผํ•œ ์ ์šฉํ•˜์ค‘์— ๋Œ€ํ•˜์—ฌ ๋ณด์˜ ์ฒ˜์ง์€ ๋” ์ž‘๊ณ  ๋ณด์˜ ๋ณ€ํ˜•์œจ ๋˜ํ•œ ๊ธฐ์กด ๋ณด์˜ ์ˆ˜์น˜๋ณด๋‹ค ๋” ์ž‘๋‹ค.

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Fig. 14

Effect of changing steel reinforcement area

๋ณด์˜ ๋ถ•๊ดด๋Š” ์ฒ ๊ทผ์˜ ํŒŒ๋‹จ์œผ๋กœ ์ธํ•ด ๋ฐœ์ƒํ•˜๋ฏ€๋กœ, ์ฒ ๊ทผ๋ฉด์ ์˜ ์ฆ๊ฐ€๋Š” ๋ณด์˜ ๋‚ดํ™”์„ฑ๋Šฅ์„ ํ–ฅ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค(๋” ์ ์€ ์ฒ ๊ทผ๋ฉด์ ์„ ์‚ฌ์šฉํ•œ ๋ณด์˜ ํŒŒ๊ดด ์‹œ์˜ ์ฒ˜์ง์˜ ์ˆ˜์น˜์— ์œ ์‚ฌํ•˜๊ฒŒ ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€). ์ด๊ฒƒ์€ Fig. 14(b)์—์„œ ๋ช…ํ™•ํžˆ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค. Fig. 14(c)์€ ์ฒ ๊ทผ์˜ ํ•œ๊ณ„ ๋ณ€ํ˜•์œจ์ธ 0.15์— ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€, ์ฒ ๊ทผ์˜ ์‹œ๊ฐ„์— ๋Œ€ํ•œ ๋ณ€ํ˜•์œจ์˜ ๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. Fig. 14(d)๋Š” ๋ณด ๊ฒฝ๊ฐ„ ์ค‘๊ฐ„์œ„์น˜์—์„œ ์ฒ ๊ทผ์‘๋ ฅ์˜ ์‹œ๊ฐ„์ด๋ ฅ์„ ๋ณด์—ฌ์ฃผ๋ฉฐ, ๋ณด ๋ถ•๊ดด์‹œ์˜ ์‘๋ ฅ์€ ๊ฑฐ์˜ 0์— ๋„๋‹ฌํ•œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ฒ ๊ทผ๋ฉด์ ์˜ ์ฆ๊ฐ€๋Š” ๋‚ดํ™”์„ฑ๋Šฅ์„ ํ–ฅ์ƒ์‹œํ‚ค๋Š” ํšจ๊ณผ์ ์ธ ๋ฐฉ๋ฒ•์ด๋ผ๊ณ  ํ•  ์ˆ˜ ์—†๋‹ค. ๊ทธ ์ด์œ ๋Š” ๊ณ ์˜จ์—์„œ ์ฒ ๊ทผ์˜ ๊ฐ•๋„๋Š” ๋งค์šฐ ๋น ๋ฅด๊ฒŒ ๊ฐ์†Œํ•˜๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

3.3.2 ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ

Fig. 15๋Š” ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ์ด 10 %, 15 %, 20 % ์ผ ๋•Œ, ๋ณด์˜ ์ถ•๋ ฅ-์‹œ๊ฐ„ ๊ด€๊ณ„์™€ ์ฒ˜์ง-์‹œ๊ฐ„ ๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. 10 %๋Š” ๊ฐ€์žฅ ๋‚ฎ์€ ์—ฐ์„ฑ์œผ๋กœ์จ, ์ด ์ˆ˜์น˜๋Š” ์œ ๋กœ์ฝ”๋“œ 2(Comite Europeen 2002)๋ฅผ ์ด์šฉํ•˜์˜€๋‹ค. ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ์ด 10 %์—์„œ 15 %๋กœ ์ƒ์Šนํ•  ๋•Œ, ๋ณด์˜ ๋‚ดํ™”์„ฑ๋Šฅ์€ 162๋ถ„์—์„œ 250๋ถ„์œผ๋กœ ๋น„์•ฝ์ ์ธ ์ƒ์Šน์„ ๋ณด์˜€๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์—ฐ์„ฑ์ด 5 % ๋” ์ƒ์Šนํ•œ 20 %์ผ ๋•Œ, ๋‚ดํ™”์„ฑ๋Šฅ์€ ์•ฝ 12๋ถ„์˜ ์ฆ๊ฐ€๋ฅผ ๋ณด์—ฌ์ฃผ์—ˆ๋‹ค. ๊ทธ ์ด์œ ๋Š” ์ฒ ๊ทผ์˜ ๊ฐ•๋„๊ฐ์†Œ๊ณ„์ˆ˜์™€ ๊ด€๋ จ์ด ์žˆ๋‹ค.

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Fig. 15

Effects of changing ductility of the reinforcement

์ฒ ๊ทผ์˜ ์—ฐ์„ฑ์ด 10 %, 15 %, 20 %์ผ ๋•Œ, ์ฒ ๊ทผ์˜ ๊ฐ•๋„๋Š” 133.29 MPa, 69.21 MPa, 60.76 MPa(๊ฐ•๋„๊ฐ์†Œ๊ณ„์ˆ˜ = 0.317, 0.164, 0.144)์ด๋ฉฐ ์˜จ๋„๋Š” 720.04 ยฐC, 754.33 ยฐC, 763.29 ยฐC์ด๊ณ , ์ฒ ๊ทผ์ด ํŒŒ๊ดด๋˜๋Š” ๋‚ดํ™”์„ฑ๋Šฅ์‹œ๊ฐ„์€ ๊ฐ๊ฐ 210๋ถ„, 250๋ถ„, 262๋ถ„์ด๋‹ค. 20 % ์ด์ƒ์œผ๋กœ ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ์ด ์ฆ๊ฐ€ํ•˜๋”๋ผ๋„, ์ฒ ๊ทผ์˜ ๊ฐ•๋„๋Š” ๋” ๋น ๋ฅด๊ฒŒ ๊ฐ์†Œ๋˜๋ฏ€๋กœ ๋‚ดํ™”์„ฑ๋Šฅ์˜ ๋น„์•ฝ์ ์ธ ์ƒ์Šน์€ ์—†์„ ๊ฒƒ์ด๋‹ค.

3.3.3 ๊ฒฝ๊ฐ„/ํญ ๋น„

์ด ์—ฐ๊ตฌ์—์„œ ํ•˜์ค‘๋น„๋Š” ๊ณ ์ •๋˜์–ด ์žˆ๋‹ค. ๋ณด์˜ ํญ์ด ๊ณ ์ •์ด๊ณ  ๊ฒฝ๊ฐ„์ด ๋ณ€ํ•œ๋‹ค๋ฉด, ์žฌํ•˜๋˜๋Š” ํ•˜์ค‘์€ ๋ณ€ํ™”๋œ๋‹ค. Fig. 16(a)์™€ (b)๋Š” ๋ณด์˜ ๊ฒฝ๊ฐ„/ํญ ๋น„๊ฐ€ ๊ฐ๊ฐ 13.33โ€ฆ, 20, 26.66โ€ฆ์œผ๋กœ ๋ณ€ํ•  ๋•Œ, ๋ณด์˜ ์ถ•๋ ฅ-์‹œ๊ฐ„ ๋ณ€ํ˜•-์‹œ๊ฐ„ ๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ํ•˜์ค‘๋น„๋Š” ๋ณ€ํ•˜์ง€ ์•Š๊ธฐ ๋•Œ๋ฌธ์—, ํœจ ์„ฑ๋Šฅ์„ ์žƒ๋Š” ์‹œ๊ฐ„์€ ๋น„์Šทํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

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Fig. 16

Effects of changing the beam span/depth ratio

ํ•œ ๊ฐ€์ง€ ํฅ๋ฏธ์žˆ๋Š” ์‚ฌ์‹ค์€ ํ˜„์ˆ˜์ž‘์šฉ์ด ๋ฐœ์ƒํ•˜๋Š” ๋™์•ˆ, ๋ณด์˜ ๊ฒฝ๊ฐ„/ํญ ๋น„๊ฐ€ ๋ณ€ํ™”ํ•  ๋•Œ, ๊ฐ™์€ ์‹œ๊ฐ„์—์„œ ๋ณด๋Š” ์œ ์‚ฌํ•œ ์ฒ˜์ง์„ ๋ณด์—ฌ์ฃผ์—ˆ๋‹ค(Fig. 16(b)). ๊ทธ ์ด์œ ๋Š” ์žฌํ•˜ ํ•˜์ค‘(ํœจ ๋ชจ๋ฉ˜ํŠธ)์ด ๋ณด์˜ ์ˆ˜์ง๋ณ€์œ„์— ๋Œ€ํ•ด ์ˆ˜ ๋ฐฐ์˜ ์ธ์žฅ๋ ฅ์— ์ €ํ•ญํ•˜๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ์ด๊ฒƒ์€ ์™œ ๋ณด์˜ ๊ฒฝ๊ฐ„/ํญ ๋น„๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉด, ๋‚ดํ™”์„ฑ๋Šฅ์‹œ๊ฐ„์ด ์ฆ๊ฐ€ํ•˜๋Š” ์ง€๋ฅผ ์„ค๋ช…ํ•ด์ค„ ์ˆ˜ ์žˆ๋‹ค. ๋ณด ๊ฒฝ๊ฐ„์ด ๋Š˜์–ด๋‚˜๊ณ , ๋ณด์˜ ์ˆ˜์ง๋ณ€์œ„๊ฐ€ ๊ฐ™์„ ๋•Œ(๋ณด ๊ฒฝ๊ฐ„์ด ๋‹ค๋ฅธ ๊ฒฝ์šฐ), ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•์œจ์€ ๋‚ฎ๋‹ค. ๋”ฐ๋ผ์„œ ๋” ๊ธด ๋ณด๋Š” ์ฒ ๊ทผ์ด ํŒŒ๋‹จํ•˜๊ธฐ ์ „๊นŒ์ง€ ์ˆ˜์ง๋ณ€์œ„๊ฐ€ ๋” ์ ๊ฒŒ ๋‚˜ํƒ€๋‚˜๊ฒŒ ๋œ๋‹ค.

3.3.4 ํ•˜์ค‘๋น„

ํ•˜์ค‘๋น„๋Š” ํ™”์žฌ ์‹œ ๊ตฌ์กฐ๋ฌผ์—์„œ ์ ์šฉํ•˜์ค‘์˜ ์ •๋„๋ฅผ ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ๋Š” ๊ธฐ์กด์˜ ์ผ๋ฐ˜์ ์ธ ์—ฐ๊ตฌ๋“ค์—์„œ ์ˆ˜ํ–‰๋˜์—ˆ๋˜ ๋ณ€์ˆ˜์ด๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ ํ•˜์ค‘๋น„๋Š” ์ถ• ๊ตฌ์†์ด ์—†๋Š” ๋ณด์˜ ์ตœ๋Œ€ ํœจ ๋ชจ๋ฉ˜ํŠธ๋ฅผ ์ด์šฉํ•˜์—ฌ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค.

Fig. 17(a)์™€ (b)๋Š” ๋ณด์˜ ์ถ•๋ ฅ-์‹œ๊ฐ„๊ณผ ๋ณ€์œ„-์‹œ๊ฐ„๊ณผ์˜ ๊ด€๊ณ„๋ฅผ ํ•˜์ค‘๋น„์— ๋Œ€ํ•ด ์„œ๋กœ ๋น„๊ตํ•˜์˜€๋‹ค. ํ•˜์ค‘๋น„๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉด ํœจ ์„ฑ๋Šฅ์„ ์žƒ์„ ๋•Œ์˜ ์‹œ๊ฐ„์„ ์•ฝ 41๋ถ„ ๊ฐ€๋Ÿ‰ ๋‹จ์ถ•์‹œํ‚จ๋‹ค(Fig. 17(a)).

ํ•˜์ค‘๋น„๊ฐ€ ๋†’์€ ๋ณด์˜ ์ตœ์ข… ๋‚ดํ™”์„ฑ๋Šฅ์‹œ๊ฐ„์€ ํ•˜์ค‘๋น„๊ฐ€ ๋‚ฎ์€ ๋ณด์˜ ๊ฒƒ๋ณด๋‹ค ์ ๊ณ , ๊ทธ ์ฐจ์ด๋Š” ์•ฝ 20๋ถ„ ์ •๋„์ด๋‹ค(Fig. 17). ๋‚ดํ™”์„ค๊ณ„ ์‹œ, ๊ฑด์„ค๋น„์šฉ์„ ์ค„์ด๊ธฐ ์œ„ํ•ด, ๋ณด์˜ ์ ์šฉํ•˜์ค‘์„ ๋‘๋“œ๋Ÿฌ์ง€๊ฒŒ ์ค„์ผ ์ˆ˜๋Š” ์—†๋‹ค. ๋”ฐ๋ผ์„œ ์ด ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์„ ์—ฐ์žฅํ•˜๋Š” ๋ฐ ์žˆ์–ด์„œ ํšจ๊ณผ์ ์ธ ๋ฐฉ๋ฒ•์ด๋ผ๊ณ  ์ œ์•ˆํ•˜๊ธฐ๋Š” ์–ด๋ ต๋‹ค.

3.3.5 ํ”ผ๋ณต๋‘๊ป˜์˜ ์˜ํ–ฅ

Fig. 18(a)์™€ (b)๋Š” ๊ฐ ํ”ผ๋ณต๋‘๊ป˜์— ๋”ฐ๋ฅธ ๋ณด์˜ ์ถ•๋ ฅ-์‹œ๊ฐ„๊ณผ ๋ณ€์œ„-์‹œ๊ฐ„ ๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ 50 mm์—์„œ 70 mm๋กœ ๋Š˜์–ด๋‚˜๋ฉด, ๋ณด์˜ ํœจ ์„ฑ๋Šฅ์€ ๊ฐ์†Œํ•œ๋‹ค. ์ด๋Š” ์‹ (6)์—์„œ์ฒ˜๋Ÿผ, ๋‹จ๋ฉด์˜ ์œ ํšจํญ์ด ๊ฐ์†Œ ๋•Œ๋ฌธ์— ๋ณด์˜ ํœจ ๊ฐ•๋„๊ฐ€ ์ค„์–ด๋“ค๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/PICFF37.gif (6)

/Resources/kci/JKCI.2018.30.2.115/images/PICFF38.gif = ๊ณต์นญ๊ฐ•๋„, /Resources/kci/JKCI.2018.30.2.115/images/PICFF49.gif = ์ค‘๋ฆฝ์ถ• ๊ธธ์ด, /Resources/kci/JKCI.2018.30.2.115/images/PICFF4A.gif = ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„,

/Resources/kci/JKCI.2018.30.2.115/images/PICFF5A.gif = ๋ณด์˜ ํญ, /Resources/kci/JKCI.2018.30.2.115/images/PICFF5B.gif = ๋‹จ๋ฉด์˜ ์œ ํšจ๊ธธ์ด

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F17.jpg

Fig. 17

Effect of changing the load ratio

๋‹ค๋ฅธ ํ•œํŽธ์œผ๋กœ, ๋” ํฐ ํ”ผ๋ณต๋‘๊ป˜๋ฅผ ๊ฐ€์ง„ ๋ณด๊ฐ€ ํŒŒ๊ดด๋˜๋Š” ์‹œ๊ฐ„์€ ์ž‘์€ ํ”ผ๋ณต๋‘๊ป˜๋ฅผ ๊ฐ€์ง„ ๋ณด์˜ ๊ฒƒ๋ณด๋‹ค ๋” ํฌ๋‹ค. ๊ทธ ์ด์œ ๋Š” ๋‚ฎ์€ ์ฒ ๊ทผ์˜จ๋„ ๋•Œ๋ฌธ์ด๋‹ค. ๊ทธ๋Ÿผ์—๋„ ๋ถˆ๊ตฌํ•˜๊ณ , Fig. 18์—์„œ ๋ณด์—ฌ์ง€๋Š” ๋ณด์˜ ์ด ์ƒ์กด์‹œ๊ฐ„์˜ ์ฐจ์ด๋Š” ๋งค์šฐ ์ ๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F18.jpg

Fig. 18

Effects of changing the steel reinforcement location

3.3.6 ์ถ• ๊ตฌ์† ์ •๋„

์‹ค์ œ ๊ฑด์ถ•๋ฌผ์—์„œ ๋ณด์˜ ์ถ• ๊ตฌ์† ์ •๋„๋Š” ๋ถ€์žฌ ์ฃผ์œ„์˜ ๊ตฌ์กฐ๋ฌผ์— ์˜ํ•ด ๊ฒฐ์ •๋œ๋‹ค. ๋”ฐ๋ผ์„œ ์ดˆ๊ธฐ ์ถ• ๊ตฌ์†์€ ํ˜„์‹ค์ ์ธ ๊ฐ€์ •์ด๋ผ๊ณ  ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด ๋ณ€์ˆ˜๋ฅผ ์ด์šฉํ•˜์—ฌ, ์ถ• ๊ตฌ์†๋œ ๋ณด์˜ ๊ฑฐ๋™์ด ๊ตฌ์†๋œ ์ •๋„์— ๋”ฐ๋ผ ์–ด๋– ํ•œ ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š”์ง€์— ๋Œ€ํ•ด ์•Œ์•„๋ณด๋Š” ๊ฒƒ์ด ์ด ์—ฐ๊ตฌ์˜ ํ•ต์‹ฌ์ด๋‹ค. ๋ณ€ํ™˜ ๊ฐ€๋Šฅํ•œ ์ถ• ๊ตฌ์†์„ ๋ชจ๋ธ๋ง ํ•˜๊ธฐ ์œ„ํ•ด, ๋ณด ๋‹จ๋ฉด ์ค‘์•™ ๋ถ€๋ถ„์— ์Šคํ”„๋ง์„ ์„ค์น˜ํ•˜์˜€๋‹ค(3.3์ ˆ์˜ Fig. 13(b)). ๋ณด ๋‹จ๋ถ€์˜ ๋” ์ž์—ฐ์Šค๋Ÿฌ์šด ํšŒ์ „์„ ์œ„ํ•˜์—ฌ ๋‹จ๋ฉด์— ๋‹ค๋ฅธ ์ ˆ์ ์—์„œ ์ถ”๊ฐ€์ ์ธ ๊ตฌ์† ์Šคํ”„๋ง์€ ์„ค์น˜๋˜์ง€ ์•Š์•˜๋‹ค.

Fig. 19์—์„œ ๋‚˜ํƒ€๋‚˜๋“ฏ์ด ๋ณด์˜ ์••์ถ•๋ ฅ์€ ๋ณด์˜ ๊ตฌ์† ๊ฐ•์„ฑ์ด ์ค„์–ด๋“ค์ˆ˜๋ก, ๊ธฐํ•˜๊ธ‰์ˆ˜์ ์œผ๋กœ ์ค„์–ด๋“ค์—ˆ๋‹ค. ๋”ฐ๋ผ์„œ ๋” ๋‚ฎ์€ ๊ตฌ์† ๊ฐ•์„ฑ์„ ๊ฐ€์ง„ ๋ณด๋Š” ํœจ๊ณผ ์••์ถ•์ด ๊ณต์กดํ•˜์—ฌ ์ผ์‹œ์ ์œผ๋กœ ์‹คํŒจํ•˜๋Š” ์ง€์ ์—์„œ ๋” ์˜ค๋ž˜ ์ €ํ•ญํ•  ์ˆ˜ ์žˆ์—ˆ๋‹ค. ํ˜„์ˆ˜์ž‘์šฉ์ด ๋ฐœ์ƒํ•˜๋Š” ๋™์•ˆ, ๋ณด ๊ฑฐ๋™์€ ๋งค์šฐ ์œ ์‚ฌํ•œ ์••์ถ•๋ ฅ๊ณผ ์ฒ˜์ง์„ ๋ณด์ด๋ฉด์„œ ๊ฑฐ์˜ ๋ณ€ํ™”ํ•˜์ง€ ์•Š๋Š” ๋ชจ์Šต์„ ๋ณด์˜€๋‹ค. ๊ทธ ์ด์œ ๋Š” ํ˜„์ˆ˜์ž‘์šฉ ๋‹จ๊ณ„์—์„œ ๋ณด์˜ ์ธ์žฅ๋ ฅ์€ ์ฒ ๊ทผ์˜ ์ธ์žฅ ์ €ํ•ญ๋Šฅ๋ ฅ์—์„œ ์˜ค๊ธฐ ๋•Œ๋ฌธ์ด๋ฉฐ, ์ด ๊ฐ’์€ ์ถ• ๊ตฌ์† ์ •๋„์— ์˜ํ–ฅ์„ ๋ฐ›์ง€ ์•Š๋Š”๋‹ค. ํ˜„์ˆ˜์ž‘์šฉํ•˜์—์„œ ๋ณด์˜ ์ €ํ•ญ๋Šฅ๋ ฅ์€ ๋ณด๊ฐ€ ์ฒ˜์ง€๋ฉด์„œ ๋ฐœ์ƒํ•˜๋Š” ์ธ์žฅ๋ ฅ์œผ๋กœ๋ถ€ํ„ฐ ๊ธฐ์ธํ•˜๊ธฐ ๋•Œ๋ฌธ์—, ๋ณด์˜ ์ฒ˜์ง์€ ์œ ์‚ฌํ•˜๋‹ค(Fig. 19(b)). ๋ณด์˜ ํŒŒ๊ดด๋Š” ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•์œจ์ด ์ตœ๋Œ€ ๋ณ€ํ˜•์œจ์— ๋„๋‹ฌ(15 %)ํ•  ๋•Œ์— ์ผ์–ด๋‚œ๋‹ค. Table 3์€ ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์„ ๋น„๊ตํ•œ ๊ฒƒ์ด๋‹ค. ์ถ• ๊ตฌ์† ๊ฐ•์„ฑ์ด ์กด์žฌํ•  ๋•Œ, ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์˜ ์ฐจ์ด๋Š” ๊ฑฐ์˜ ์—†๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F19.jpg

Fig. 19

Effects of changing the steel reinforcement location

Table 3 Effects of changing the axial restraint stiffness on the beam survival time

/Resources/kci/JKCI.2018.30.2.115/images/Table_CONCRETE_30_2_01_T3.jpg

4. ๊ฒ€์ฆ๊ณผ์ •

๋ณธ ์—ฐ๊ตฌ์—์„œ ์‹คํ—˜๊ฐ’์€ ์ €์ž๋“ค์—๊ฒŒ ์š”์ฒญํ•˜์—ฌ ๋ฐ›์€ ๋ฐ์ดํ„ฐ ๊ฐ’์„ ์ด์šฉํ•˜์˜€์Œ์„ ๋ฐํ˜€๋‘”๋‹ค. ์ฒซ ๋ฒˆ์งธ๋Š” Yu and Tan(2013)์ด 2010๋…„์— ์ˆ˜ํ–‰ํ•˜์˜€์œผ๋ฉฐ Fig. 20์—์„œ ์ž˜ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค. Fig. 21์€ ์ถ•๊ตฌ์†์„ ๊ฐ€์ง„ ๋ณด์˜ ์‹คํ—˜๊ฐ’๊ณผ ์ˆ˜์น˜ํ•ด์„ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F20.jpg

Fig. 20

Test specimen and boundary condition (Yu and Tan 2013)

๋‘ ๋ฒˆ์งธ๋Š” ์ค‘๊ตญ์—์„œ Yi et al.(2008)๊ฐ€ 2008๋…„์— ์ˆ˜ํ–‰ํ•œ ์ƒ์˜จ์—์„œ ํ”„๋ ˆ์ž„ ๊ตฌ์กฐ์‹คํ—˜ํ•œ ๊ฒƒ์„ ๋ชจ๋ธ๋ง ํ•˜์˜€๋‹ค(Fig. 22). ์‹ค์ œ๊ตฌ์กฐ๋ฌผ์˜ 1/4์Šค์ผ€์ผ๋กœ ์ œ์ž‘๋˜์—ˆ์œผ๋ฉฐ ํ•ด์„ ๊ฒฐ๊ณผ์™€ ์‹คํ—˜๊ฐ’์˜ ๋น„๊ต๋Š” Fig. 23์—์„œ ์ž˜ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค.

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F21.jpg

Fig. 21

Comparison between test and simulations

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F22.jpg

Fig. 22

Location of measurement location for the test frame (Location of horizontal displacement measurement (position A) and concrete strain measurement (Top: B, Bottom: C))

/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F23.jpg

Fig. 23

Comparison test and simulations results

2009๋…„์— Dwaikat and Kodur(2009)๋Š” ํ™”์žฌ ์‹œ ์ถ• ๊ตฌ์†์ด ์žˆ๋Š” R.C๋ณด์˜ ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค(1.2์ ˆ์˜ Fig. 6). Fig. 24๋Š” ๋ชจ๋“  ์‹คํ—˜์ฒด์— ๋Œ€ํ•˜์—ฌ ์ˆ˜์น˜ํ•ด์„ ๊ฒฐ๊ณผ์™€ ์‹คํ—˜๊ฐ’์„ ๋น„๊ตํ•œ ๊ทธ๋ž˜ํ”„์ด๊ณ , ์ƒ๋‹นํžˆ ๋น„์Šทํ•œ ๊ฒฐ๊ณผ๊ฐ€ ๋‚˜์™”์œผ๋ฉฐ, ์‹คํ—˜์ฒด์˜ ์ƒ์„ธ์™€ ๋‹จ๋ถ€์กฐ๊ฑด๋“ฑ์€ Table 4์— ์ž˜ ๋‚˜์™€์žˆ๋‹ค. ์ด ์‹คํ—˜์—์„œ ์‹คํ—˜์ฒด B2์™€ B6๋Š” ์ถ• ๊ตฌ์†์ด ์žˆ์—ˆ์Œ์—๋„ ํ˜„์ˆ˜์ž‘์šฉ์€ ๋ฐœ์ƒํ•˜์ง€ ์•Š์•˜๋‹ค. ๊ทธ ์ด์œ ๋Š” 1.2์ ˆ์—์„œ ์„ค๋ช…ํ•˜์˜€๋“ฏ์ด ํ™”์žฌ์˜ ๋…ธ์ถœ ์ •๋„๊ฐ€ ๋‚ฎ์•˜๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

Table 4 Test specimen details and conditions (Dwaikat and Kodur 2009)

/Resources/kci/JKCI.2018.30.2.115/images/Table_CONCRETE_30_2_01_T4.jpg
/Resources/kci/JKCI.2018.30.2.115/images/Figure_CONCRETE_30_2_01_F24.jpg

Fig. 24

Comparison between test and simulation results for vertical deflection

5. ๊ฒฐ    ๋ก 

์ถ• ๊ตฌ์†๋œ ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์€ ๋ณด์˜ ํœจ ํŒŒ๊ดด์‹œ์˜ ์‹œ๊ฐ„๋ณด๋‹ค ํ›จ์”ฌ ๋” ๊ธธ๋‹ค. ์ถ• ๊ตฌ์†์˜ ์˜ํ–ฅ์€ ํ™”์žฌ ์‹œ R.C๊ตฌ์กฐ๋ฌผ์˜ ๊ฐ•๊ฑด์„ฑ์˜ ์ด์ ์„ ์œ„ํ•ด ์‚ฌ์šฉ๋  ์ˆ˜ ์žˆ๋‹ค. ์ฒ ๊ทผ์˜ ๋ฉด์ ์„ ์ฆ๊ฐ€์‹œํ‚ค๋ฉด ๋ณด์˜ ํœจ ํŒŒ๊ดด์‹œ๊ฐ„๊ณผ ์ƒ์กด์‹œ๊ฐ„์„ ๋Š˜๋ฆด ์ˆ˜ ์žˆ๋‹ค. ์ด๋•Œ ๋ณด์— ๋ฐœ์ƒํ•˜๋Š” ์••์ถ•๋ ฅ์€ ์•ฝ๊ฐ„ ์ƒ์Šนํ•œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ํœจ ํŒŒ๊ดด์‹œ๊ฐ„๊ณผ ์ƒ์กด์‹œ๊ฐ„์˜ ์ƒ์Šน์€ ํฌ์ง€ ์•Š๋‹ค. ๊ทธ๋Ÿฌ๋ฏ€๋กœ ์ฒ ๊ทผ ๋ฉด์ ์˜ ์ƒ์Šน์ด ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์„ ์—ฐ์žฅ์‹œํ‚ค๋Š”๋ฐ ๋งค์šฐ ํšจ๊ณผ์ ์ด๋ผ๊ณ  ํ•  ์ˆ˜๋Š” ์—†๋‹ค. ์ฒ ๊ทผ์˜ ์—ฐ์„ฑ์ฆ๊ฐ€๋Š” ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„ ์ƒ์Šน์—๋งŒ ์˜ํ–ฅ์„ ๋ฏธ์นœ๋‹ค. ์ด ํšจ๊ณผ๋Š” ์ƒ๋Œ€์ ์œผ๋กœ ๋‚ฎ์€ ๋ณ€ํ˜•์œจ์„ ๊ฐ€์ง„ ์ฒ ๊ทผ(10 %)์— ๋น„ํ•ด์„œ๋Š” ๋งค์šฐ ํฌ๋‹ค๊ณ  ํ•  ์ˆ˜ ์žˆ๋‹ค. ํ•˜์ง€๋งŒ ํ˜„์žฌ ์‹ค์ œ๋กœ ์‚ฌ์šฉ๋˜๋Š” ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•์œจ์€ ๋‚ฎ๊ธฐ(์•ฝ 5 %)๋•Œ๋ฌธ์— ์ฒ ๊ทผ์ œ์ž‘ ๋‹จ๊ณ„์—์„œ ๋ณ€ํ˜•์œจ์„ ์ƒ์Šน์‹œํ‚ค๊ธฐ ์œ„ํ•œ ๋…ธ๋ ฅ์€ ๊ฐ€์น˜๊ฐ€ ์žˆ๋‹ค.

๋ณด์˜ ๊ฒฝ๊ฐ„/ํญ ๋น„์˜ ์ƒ์Šน์€ ๋ณด์—์„œ ํ˜„์ˆ˜์ž‘์šฉ์ด ์ƒ์„ฑ๋˜๋Š”๋ฐ ๋„์›€์ด ๋˜๋Š” ๊ฒฝํ–ฅ์ด ์žˆ๊ณ  ์ด๋Š” ์ƒ์กด์‹œ๊ฐ„์˜ ์ƒ์Šน์œผ๋กœ ์ด์–ด์งˆ ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ ์ตœ๋Œ€ ์••์ถ•๋ ฅ์„ ๊ฐ์†Œ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค. ํ•˜์ค‘๋น„ ๊ฐ์†Œ๋Š” ๋ณด์˜ ํœจ ํŒŒ๊ดด์™€ ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์„ ๋Š˜๋ฆด ์ˆ˜ ์žˆ์ง€๋งŒ, ์ ์šฉํ•˜์ค‘์˜ ๊ฐ์†Œ๋กœ ๊ฑด์ถ•๋น„๋ฅผ ๋‘๋“œ๋Ÿฌ์ง€๊ฒŒ ๊ฐ์†Œ์‹œํ‚ฌ ์ˆ˜ ์—†์œผ๋ฏ€๋กœ, ๋ณด ๊ฐ•๊ฑด์„ฑ์„ ํ–ฅ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋Š” ์ฃผ๋œ ๋ฐฉ๋ฒ•์œผ๋กœ ์ถ”์ฒœ๋  ์ˆ˜ ์—†๋‹ค. ์ถ• ๊ตฌ์† ์ •๋„๊ฐ€ ์•„์ฃผ ์ ๋”๋ผ๋„(์•ฝ 1 %์˜ ์ถ• ๊ตฌ์†), ๋ณด๋Š” ๋‚ดํ™”์„ฑ๋Šฅ ์‹œ๊ฐ„์„ ์ƒ๋‹นํ•˜๊ฒŒ ์ฆ๊ฐ€์‹œํ‚ฌ ์ˆ˜ ์žˆ๋Š” ํ˜„์ˆ˜์ž‘์šฉ์„ ๋ฐœ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค. ์ถ• ๊ตฌ์† ์ •๋„๊ฐ€ ์ฆ๊ฐ€ํ•  ๋•Œ, ๋ณด์˜ ์ƒ์กด์‹œ๊ฐ„์— ๋Œ€ํ•œ ๋ณ€ํ™”๋Š” ๋งค์šฐ ์ ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณด๋Š” ๋ฌดํ•œ๋Œ€์˜ ์ถ• ๊ตฌ์†์„ ๊ฐ–๋Š”๋‹ค๊ณ  ๊ฐ€์ •ํ•˜์—ฌ๋„ ๊ฒฐ๊ณผ์น˜์— ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜์ง€๋Š” ์•Š์„ ๋“ฏ ํ•˜๋‹ค.

Acknowledgements

์ด ์—ฐ๊ตฌ๋Š” ์‚ฐ์—…ํ†ต์ƒ์ž์›๋ถ€์™€ ํ•œ๊ตญ์—๋„ˆ์ง€๊ธฐ์ˆ ํ‰๊ฐ€์›์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰๋˜์—ˆ์Šต๋‹ˆ๋‹ค. ์—ฐ๊ตฌ๊ณผ์ œ ๋ฒˆํ˜ธ๋Š” 20161510 400110(โ€œ์›์ „ ๊ด‘์—ญํ™”์žฌ๋ฅผ ๊ณ ๋ คํ•œ ์ •๋Ÿ‰์  ํ™”์žฌ์˜ํ–ฅํ‰๊ฐ€โ€)์ž…๋‹ˆ๋‹ค.

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