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  1. ๋‹จ๊ตญ๋Œ€ํ•™๊ต ๊ฑด์ถ•ํ•™๋ถ€ ๋Œ€ํ•™์›์ƒ (Graduate Student, School of Architecture, Dankook University, Yongin 16890, Rep. of Korea)
  2. ๋‹จ๊ตญ๋Œ€ํ•™๊ต ๊ฑด์ถ•ํ•™๋ถ€ ๊ต์ˆ˜ (Professor, School of Architecture, Dankook University, Yongin 16890, Rep. of Korea)
  3. KCL ๋‚ด์ง„์„ผํ„ฐ ์ฑ…์ž„์—ฐ๊ตฌ์› (Senior Researcher, Seismic Safety Center, KCL, Cheongju 28115, Rep. of Korea)
  4. (์ฃผ)AMS ์—ฐ๊ตฌ์†Œ ์†Œ์žฅ (Director, Laboratory, AMS Engineering, Daegeon 34077, Rep. of Korea)
  5. (์ฃผ)AMS ๋Œ€ํ‘œ (CEO, AMS Engineering, Daegeon 34077, Rep. of Korea)



๋น„๋ณด๊ฐ•์กฐ์ , ์กฐ์ ๋ฒฝ, ECC ์ž์ผ“, ๊ฐ•์ฒดํšŒ์ „, ๋‚ด์ง„๋ณด๊ฐ•
unreinforced masonry, masonry wall, ECC jacket, rocking, seismic retrofit

1. ์„œ ๋ก 

์ตœ๊ทผ ํŒŒ์ถœ์†Œ, ๊ฒฝ๋กœ๋‹น, ๋‹จ๋…์ฃผํƒ ๋“ฑ ๋…ธํ›„ ์†Œ๊ทœ๋ชจ ์กฐ์ ๊ฑด๋ฌผ์— ๋Œ€ํ•œ ๋‚ด์ง„์„ฑ๋Šฅํ‰๊ฐ€ ๋ฐ ๋ณด๊ฐ•์— ๋Œ€ํ•œ ์ˆ˜์š”๊ฐ€ ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ๋‹ค. ์ด๋“ค ๊ฑด๋ฌผ์€ ๋Œ€๋ถ€๋ถ„ 2์ธต ์ดํ•˜์˜ ๊ฑด๋ฌผ๋กœ ์ค‘๋ ฅํ•˜์ค‘์„ ์ง€์ง€ํ•˜๋„๋ก ์„ค๊ณ„๋œ ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด(unreinforced masonry wall)๊ฐ€ ์ง€์ง„ํ•˜์ค‘์— ์ €ํ•ญํ•œ๋‹ค. ๋ฏธ๊ตญ์—์„œ ์ˆ˜ํ–‰๋œ 2์ธต ์กฐ์ ๊ฑด๋ฌผ์— ๋Œ€ํ•œ ์‹คํ—˜์—ฐ๊ตฌ(Costley and Abrams 1996; Moon 2004; Moon et al. 2007)์— ๋”ฐ๋ฅด๋ฉด, ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด๋Š” ๋ณด๊ฐ•์ฒ ๊ทผ์ด ์‚ฌ์šฉ๋˜์ง€ ์•Š์•˜์Œ์—๋„ ๋ถˆ๊ตฌํ•˜๊ณ  ๋ฉด๋‚ด ํšกํ•˜์ค‘ ๋Œ€ํ•˜์—ฌ ํ•ญ๋ณต์ ์ด ๋ถ„๋ช…ํ•˜๊ณ  ํ•ญ๋ณต ์ดํ›„์—๋Š” ๊ฐ•๋„๊ฐ€ ์ผ์ •ํ•˜๊ฒŒ ์œ ์ง€๋˜๋Š” ์—ฐ์„ฑ๊ฑฐ๋™(๋ณ€ํ˜•์ง€๋ฐฐ ๊ฑฐ๋™)์ด ํ™•์ธ๋œ๋‹ค. ๊ฐœ๋ณ„ ์กฐ์ ๋ฒฝ์ฒด์— ๋Œ€ํ•œ ์‹คํ—˜์—ฐ๊ตฌ์—์„œ๋„ ์ด์™€ ์œ ์‚ฌํ•œ ๋ณ€ํ˜•์ง€๋ฐฐ ๊ฑฐ๋™๋ชจ๋“œ๊ฐ€ ํ™•์ธ๋œ๋‹ค. Kang et al. (2010)์˜ ์—ฐ๊ตฌ์—์„œ๋Š” ์ผ„ํ‹ธ๋ ˆ๋ฒ„ ์กฐ์ ๋ฒฝ์ฒด(ํ˜•์ƒ๋น„ 0.67~1.33)์—์„œ ํšก๋ณ€์œ„๋น„ 2~5 %์˜ ๋ณ€ํ˜•๋Šฅ๋ ฅ์ด ํ™•์ธ๋˜์—ˆ๊ณ , Yi et al. (2005)์˜ ์—ฐ๊ตฌ์—์„œ๋Š” ๋ณต๊ณก๋ฅ  ๋ชจ๋ฉ˜ํŠธ๊ฐ€ ์ž‘์šฉํ•˜๋Š” ์กฐ์ ๋ฒฝ์ฒด(ํ˜•์ƒ๋น„ 0.75~2.25)์—์„œ ํšก๋ณ€์œ„๋น„ 1.5 % ์ด์ƒ์˜ ๋ณ€ํ˜•๋Šฅ๋ ฅ์ด ํ™•์ธ๋˜์—ˆ๋‹ค. Kanno and Choi (2021)์˜ ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด ๋‚ด์ง„์‹คํ—˜์—์„œ๋Š” ์ผ์ฒดํ˜• ์กฐ์ ๋ฒฝ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ๊ฒฝ์šฐ์—๋„ ํ•ญ๋ณต ํ›„ ์—ฐ์„ฑ๊ฑฐ๋™์ด ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Ÿฌํ•œ ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์˜ ์—ฐ์„ฑ๊ฑฐ๋™์€ ํ†ต์ƒ ์กฐ์ ๋ฒฝ์ฒด๊ฐ€ ๊ฐ•์ฒดํšŒ์ „(rocking) ๋˜๋Š” ๊ฐ€๋กœ์ค„๋ˆˆํŒŒ๊ดด(bed joint sliding)์— ์˜ํ•ด ํŒŒ๊ดด๋œ ๊ฒฝ์šฐ์— ๋‚˜ํƒ€๋‚œ๋‹ค(KISC 2013; ASCE 2013, 2017). ํŠนํžˆ, Moon et al. (2007), Kang et al. (2010), Yi et al. (2005), Kanno and Choi (2021), Abrams and Shah (1992), Esposito and Ravenshorst (2017), Mahmoudimotlagh (2020), Shabani and Kioumarsi (2022) ๋“ฑ ๋‹ค์ˆ˜์˜ ์—ฐ๊ตฌ๋ฌธํ—Œ์—์„œ ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์€ ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์˜ ์ฃผ์š”ํ•œ ๋ณ€ํ˜•์ง€๋ฐฐ ๊ฑฐ๋™๋ชจ๋“œ๋กœ ๋ณด๊ณ ๋˜์—ˆ๋‹ค.

Fig. 1์€ ์กฐ์ ๋ฒฝ์ฒด ๋ฐ ๋ฒฝ๊ธฐ๋‘ฅ(wall pier, ๊ฐœ๊ตฌ๋ถ€ ์ฃผ๋ณ€์˜ ์†Œํ˜• ๋ฒฝ์ฒด)์—์„œ ๊ด€์ฐฐ๋˜๋Š” ๊ฐ•์ฒดํšŒ์ „ํŒŒ๊ดด๋ฅผ ๋ณด์—ฌ์ค€๋‹ค(Kanno and Choi 2021; Eom et al. 2023). ์กฐ์ ๋ฒฝ์ฒด์˜ ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์€ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ํŠน์ง•์„ ๊ฐ–๋Š”๋‹ค. ์ฒซ์งธ, ๊ฐ•์ฒดํšŒ์ „์ด ๋ฐœ์ƒํ•˜๋Š” ๋™์•ˆ์—๋Š” ์กฐ์ ๋ฒฝ์ฒด์˜ ๋‚ด๋ถ€ ์†์ƒ(๊ท ์—ด ๋˜๋Š” ์••๊ดด)์€ ์ƒ๋Œ€์ ์œผ๋กœ ์ œํ•œ์ ์ด๋‹ค. ๋‘˜์งธ, ์ฐฝํ˜ธ ๋“ฑ ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์กฐ์ ๋ฒฝ์ฒด๋Š” ์ฃผ๋กœ ํ•˜๋ถ€์—์„œ ์ˆ˜ํ‰์ค„๋ˆˆํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒ(์ผ„ํ‹ธ๋ ˆ๋ฒ„ ๋˜๋Š” ๋‹จ๊ณก๋ฅ  ๊ฑฐ๋™)ํ•˜๋ฉฐ, ๊ฐœ๊ตฌ๋ถ€ ์ฃผ๋ณ€์˜ ๋ฒฝ๊ธฐ๋‘ฅ์—์„œ๋Š” ๊ฐœ๊ตฌ๋ถ€ ์ƒํ•˜ ๋ชจ์„œ๋ฆฌ์—์„œ ์ˆ˜ํ‰์ค„๋ˆˆํŒŒ๊ดด๊ฐ€ ์‹œ์ž‘(๋ณต๊ณก๋ฅ  ๊ฑฐ๋™)๋˜๋ฉฐ ์ดํ›„ ์ ์ฐจ ๋Œ€๊ฐ๊ท ์—ด๋กœ ๋ฐœ์ „ํ•œ๋‹ค(Fig. 1(b) ์ฐธ์กฐ). ์…‹์งธ, ์ฃผ๊ธฐํ•˜์ค‘์ด ์ž‘์šฉํ•˜๋Š” ๊ฒฝ์šฐ ์กฐ์ ๋ฒฝ์ฒด ์ „์ฒด๋ฅผ ๊ด€ํ†ตํ•˜๋Š” ์ˆ˜ํ‰์ค„๋ˆˆํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์—ฌ ๋ฏธ๋„๋ŸผํŒŒ๊ดด(bed joint sliding)๊ฐ€ ๋‚˜ํƒ€๋‚  ์ˆ˜ ์žˆ๋‹ค(Kanno and Choi 2021). ์ด๋Ÿฌํ•œ ๊ฐ•์ฒดํšŒ์ „์— ๋Œ€ํ•˜์—ฌ ๋‚ด์ง„๋ณด๊ฐ•์„ ์ˆ˜ํ–‰ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ๋ฒฝ์ฒด ํ•˜๋‹จ๋ถ€์™€ ๊ฐœ๊ตฌ๋ถ€ ๋ชจ์„œ๋ฆฌ์—์„œ ์ˆ˜ํ‰๊ท ์—ด ๋ฐ ๋Œ€๊ฐ๊ท ์—ด์ด ํ™•์‚ฐํ•˜๋Š” ๊ฒƒ์„ ์ง€์—ฐ์‹œํ‚ค๋Š” ๊ฒƒ์ด ํ•„์š”ํ•˜๋‹ค.

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์œ„์— ์–ธ๊ธ‰๋œ ๊ฐ•์ฒดํšŒ์ „์— ์˜ํ•œ ์กฐ์ ๋ฒฝ์ฒด ๋ฐ ๊ฐœ๊ตฌ๋ถ€ ์ฃผ๋ณ€ ๋ฒฝ๊ธฐ๋‘ฅ์˜ ๊ท ์—ด/ํŒŒ๊ดด๋ฅผ ๋ฐฉ์ง€ํ•˜๊ณ  ๋‚ด์ง„์„ฑ๋Šฅ์„ ํ–ฅ์ƒ์‹œํ‚ค๊ณ ์ž ์™ธ๋ถ€ ํ‘œ๋ฉด์„ ๊ณ ์ธ์„ฑ๋ชจ๋ฅดํƒ€๋ฅด(engineered cementitious composite, ECC)๋กœ ์ž์ผ“ํŒ…(๋‘๊ป˜ 40 mm ์ด์ƒ)ํ•˜์—ฌ ์กฐ์ ์„ ๋ณด๊ฐ•ํ•˜๋Š” ECC ์ž์ผ“๊ณต๋ฒ•์„ ์—ฐ๊ตฌํ•˜์˜€๋‹ค. ๋ณ„๋„์˜ ์ •์ฐฉ์žฅ์น˜ ์—†์ด ์„ฌ์œ ๋ณด๊ฐ•์‹œํŠธ๋ฅผ ์กฐ์ ๋ฒฝ์ฒด ํ‘œ๋ฉด์— ๋ถ€์ฐฉํ•˜๋Š” ์ผ๋ฐ˜ ํƒ„์†Œ์„ฌ์œ ๋ณด๊ฐ• ๋˜๋Š” ์•„๋ผ๋ฏธ๋“œ์„ฌ์œ ๋ณด๊ฐ•๊ณผ ๋‹ฌ๋ฆฌ, ECC ์ž์ผ“๊ณต๋ฒ•์€ Fig. 2์™€ ๊ฐ™์ด ๋ณ„๋„์˜ ์•ต์ปค ๋ฐ ๋ณด๊ฐ•์ฒ ๊ทผ์„ ์‚ฌ์šฉํ•˜์—ฌ ECC ์ž์ผ“์„ ์ƒํ•˜ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด/์Šฌ๋ž˜๋ธŒ์— ์ง์ ‘ ๊ณ ์ •ํ•จ์œผ๋กœ์จ ์‹ ๊ตฌ ๊ตฌ์กฐ ์‚ฌ์ด ์ผ์ฒด์„ฑ์„ ์ฆ์ง„ํ•˜๊ณ  ์ง€์ง„ํ•˜์ค‘ ์ „๋‹ฌ ๊ฒฝ๋กœ๋ฅผ ํ™•๋ณดํ•œ๋‹ค. ๋˜ํ•œ ECC ์ž์ผ“ ๋‚ด๋ถ€์— ์™€์ด์–ด๋ฉ”์‹œ๋ฅผ ๋ณ„๋„๋กœ ์ถ”๊ฐ€ํ•จ์œผ๋กœ์จ ECC ์ž์ผ“์˜ ๊ท ์—ด ๋ฐ ์†์ƒ์„ ์–ต์ œํ•œ๋‹ค. Fig. 2์—์„œ ๋ณด๋“ฏ์ด ECC ์ž์ผ“๊ณต๋ฒ•์˜ ์ฃผ์š” ๊ตฌ์„ฑ์š”์†Œ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

โ€ข ์•ต์ปค์ ‘ํ•ฉ๋ถ€ ๋ฐ ๋ณด๊ฐ•์ฒ ๊ทผ(Fig. 2(a) ์ฐธ์กฐ): ECC ์ž์ผ“์€ ์ฝ˜ํฌ๋ฆฌํŠธ ์•ต์ปค(๋ถ€์ฐฉ์‹์•ต์ปค)์— ์˜ํ•ด ๊ธฐ์กด ๊ฑด๋ฌผ์˜ ์Šฌ๋ž˜๋ธŒ ๋˜๋Š” ํ…Œ๋‘๋ฆฌ๋ณด์™€ ์—ฐ๊ฒฐ๋œ๋‹ค. ์•ต์ปค์ ‘ํ•ฉ๋ถ€๋กœ๋ถ€ํ„ฐ ์ ‘ํ•ฉ๋ฉด์„ ๊ฐ€๋กœ์งˆ๋Ÿฌ ์ˆ˜์ง์œผ๋กœ ์—ฐ์žฅ๋˜๋Š” ๋ณด๊ฐ•์ฒ ๊ทผ(D10)์€ ํ•˜์ค‘์ „๋‹ฌ๊ตฌ๊ฐ„์—์„œ ์‘๋ ฅ์ง‘์ค‘์— ์˜ํ•œ ECC ์ž์ผ“์˜ ์†์ƒ ๋ฐ ํŒŒ๊ดด๋ฅผ ๋ฐฉ์ง€ํ•œ๋‹ค.

โ€ข ECC ์ž์ผ“ ๋ฐ ์™€์ด์–ด๋ฉ”์‹œ: PVC ๊ณ„์—ด ์„ฌ์œ ๋ฅผ ํ˜ผ์ž…ํ•œ ์‹œ๋ฉ˜ํŠธ๋ชจ๋ฅดํƒ€๋ฅด๋กœ์จ ECC ์ž์ผ“์€ ์ตœ์†Œํ•œ 40 mm ์ด์ƒ์˜ ๋‘๊ป˜๋กœ ์‹œ๊ณต๋œ๋‹ค. Fig. 2(c)~2(e)์™€ ๊ฐ™์ด ์™€์ด์–ด๋ฉ”์‹œ, ์กฐ์ ์•ต์ปค ๋ฐ ๊ณ ์ •ํด๋ฆฝ์„ ์‚ฌ์šฉํ•˜์—ฌ ECC ์ž์ผ“์ด ๋„“์€ ์กฐ์ ๋ฒฝ๋ฉด์— ๋ฌผ๋ฆฌ์ ์œผ๋กœ ์—ฐ๊ฒฐ๋˜๋„๋ก ์‹œ๊ณต๋œ๋‹ค.

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๋ณด๊ฐ• ๋ฐ ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์— ๋Œ€ํ•œ ๋‚ด์ง„์‹คํ—˜์„ ํ†ตํ•˜์—ฌ ECC ์ž์ผ“๊ณต๋ฒ•์˜ ๋‚ด์ง„๋ณด๊ฐ• ํšจ๊ณผ๋ฅผ ๊ฒ€์ฆํ•˜์˜€๋‹ค. ๊ตญ๋‚ด ๋…ธํ›„ ๊ฑด๋ฌผ์˜ ์กฐ์ ์ƒํƒœ๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๋‚ด์ง„์‹คํ—˜์„ ๊ณ„ํšํ•˜์˜€๊ณ , ๊ณต๊ฐ„์Œ“๊ธฐ(cavity wall) ๋ฐ ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์กฐ์ ๋ฒฝ์ฒด ๋‚ด์ง„์„ฑ๋Šฅ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์กฐ์‚ฌํ•˜์˜€๋‹ค. ์ด ๋…ผ๋ฌธ์—์„œ๋Š” ECC ์ž์ผ“๊ณต๋ฒ•์˜ ๊ตฌ์กฐ์ƒ์„ธ๋ฅผ ํฌํ•จํ•˜์—ฌ ๋ณด๊ฐ• ๋ฐ ๋น„๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์— ๋Œ€ํ•œ ๋‚ด์ง„์‹คํ—˜ ๋ฐ์ดํ„ฐ๋ฅผ ์ค‘์‹ฌ์œผ๋กœ ๊ธฐ์ˆ ํ•˜์˜€๋‹ค.

Fig. 1 Rocking failure modes in unreinforced masonry walls and wall piers
../../Resources/KCI/JKCI.2023.35.4.397/fig1.png
Fig. 2 Construction process of engineered cementitious composite (ECC) jacket for seismic retrofit of a masonry building
../../Resources/KCI/JKCI.2023.35.4.397/fig2.png

2. ์‹คํ—˜ ๊ณ„ํš

2.1 ์‹คํ—˜๋ณ€์ˆ˜ ๋ฐ ์‹คํ—˜์ฒด ํ˜•์ƒ

์ด 6๊ฐœ์˜ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด๋ฅผ ์ œ์ž‘ํ•˜์—ฌ ๋ฐ˜๋ณต๊ฐ€๋ ฅ ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. Table 1์—์„œ ๋ณด๋“ฏ์ด ECC ์ž์ผ“, ๊ณต๊ฐ„์Œ“๊ธฐ ๋ฐ ๊ฐœ๊ตฌ๋ถ€ ์„ค์น˜ ์—ฌ๋ถ€๋ฅผ ์‹คํ—˜๋ณ€์ˆ˜๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค. ์‹คํ—˜์ฒด ์ด๋ฆ„์—์„œ #1-#6์€ ์‹คํ—˜์ฒด ์ผ๋ จ๋ฒˆํ˜ธ๋ฅผ, C ๋ฐ S๋Š” ๊ฐ๊ฐ ๊ณต๊ฐ„์Œ“๊ธฐ ๋ฐ ์ผ๋ฐ˜์Œ“๊ธฐ ์กฐ์ ๋ฒฝ์ฒด๋ฅผ, NJ ๋ฐ FJ๋Š” ๊ฐ๊ฐ ๋น„๋ณด๊ฐ• ๋ฐ ECC ์ž์ผ“๋ณด๊ฐ•์„, O๋Š” ๊ฐœ๊ตฌ๋ถ€๋ฅผ ๊ฐ€๋ฆฌํ‚จ๋‹ค.

๋ณด๊ฐ• ์ด์ „ ์กฐ์ ๋ฒฝ์ฒด์˜ ํ˜•์ƒ ๋ฐ ์น˜์ˆ˜๋Š” Fig. 3์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์กฐ์ ๋ฒฝ์ฒด์˜ ๊ธธ์ด ๋ฐ ๋†’์ด๋Š” ๊ฐ๊ฐ 1,990 mm ๋ฐ 1,350 mm์ด๊ณ  ๋ฒฝ์ฒด ํ˜•์ƒ๋น„(๋†’์ด/๊ธธ์ด)๋Š” 0.678์ด๋‹ค. ์‹คํ—˜์ฒด #1 ๋ฐ #2์—๋Š” 1.5B์Œ“๊ธฐ๋ฅผ ์ ์šฉํ•˜์˜€๊ณ , ์‹คํ—˜์ฒด #3-#6์€ ๋ฒฝ์ฒด๊ฐ€ ์™ผ์ชฝ์œผ๋กœ ์น˜์šฐ์นœ 1.0B ํŽธ์‹ฌ์Œ“๊ธฐ๋ฅผ ์ ์šฉํ•˜์˜€๋‹ค. ์‹คํ—˜์ฒด #5 ๋ฐ #6์˜ ์ฐฝํ˜ธํ˜• ๊ฐœ๊ตฌ๋ถ€ ํฌ๊ธฐ๋Š” 710 mmร—680 mm์ด๋‹ค. ๋ชจ๋“  ์‹คํ—˜์ฒด์—์„œ ์กฐ์ ๋ฒฝ์ฒด๋Š” ๋‹จ๋ฉดํฌ๊ธฐ 300 mmร—300 mm์˜ ์ƒํ•˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด ์‚ฌ์ด์— ์„ค์น˜ํ•˜์˜€์œผ๋ฉฐ, ๋ณด์˜ ๊ธธ์ด๋ฐฉํ–ฅ ๋ฐ ์ง๊ฐ๋ฐฉํ–ฅ ๋ณด๊ฐ•์ฒ ๊ทผ์œผ๋กœ๋Š” ๊ฐ๊ฐ 4-D19 ๋ฐ D10@150(ํ›„ํ”„)๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ์‹คํ—˜์ฒด๋Š” ๋…ธํ›„ ์กฐ์ ๊ฑด๋ฌผ 1์ธต ๋ฒฝ์ฒด์˜ ์•ฝ 2/3 ํฌ๊ธฐ๋กœ ์„ค๊ณ„๋˜์—ˆ์œผ๋ฉฐ, ๊ฐœ๊ตฌ๋ถ€์˜ ํฌ๊ธฐ ๋ฐ ์œ„์น˜๋Š” ๋น„๊ต๋ถ„์„์„ ์œ„ํ•˜์—ฌ Kanno and Choi (2021) ์—ฐ๊ตฌ๋ฅผ ์ฐธ๊ณ ํ•˜์˜€๋‹ค. ๋˜ํ•œ ์‹คํƒœ์กฐ์‚ฌ๋œ ์‹ค์ œ ๊ฑด๋ฌผ์˜ ๋ณด๊ฐ•์ƒ์„ธ๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ์กฐ์ ์„ ํŽธ์‹ฌ์Œ“๊ธฐ๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค.

Fig. 4๋Š” ๊ธฐ์ดˆ ๋ฐ ํ•˜๋ถ€๋ณด์™€ ์กฐ์ ๋ฒฝ์ฒด์˜ ์‹œ๊ณต๊ณผ์ •์„ ๋ณด์—ฌ์ค€๋‹ค. ํ•˜๋ถ€์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ธฐ์ดˆ ๋ฐ ๋ณด๋ฅผ ๋จผ์ € ์‹œ๊ณตํ•œ ๋‹ค์Œ ๋ฒฝ๋Œ์„ ์Œ“์•„ ์˜ฌ๋ ค ์‹คํ—˜์ฒด๋ฅผ ์ œ์ž‘ํ•˜์˜€๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์™€ ์กฐ์ ๋ฒฝ์ฒด ์‚ฌ์ด ์ ‘ํ•ฉ๋ฉด์—์„œ ๋ฏธ๋„๋Ÿผ์„ ๋ฐฉ์ง€ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ Fig. 4(a)์™€ ๊ฐ™์ด ์ฒ ๊ทผ ์ „๋‹จํ‚ค๋ฅผ 500 mm ๊ฐ„๊ฒฉ์œผ๋กœ ์„ค์น˜ํ•˜์˜€๋‹ค. 1.5B ๊ณต๊ฐ„์Œ“๊ธฐ๊ฐ€ ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด #1 ๋ฐ #2์—์„œ๋Š” ๋‹จ์—ด์žฌ๊ฐ€ ์กด์žฌํ•˜๋Š” ๊ฒฝ์šฐ๋ฅผ ์ƒ์ •ํ•˜์—ฌ ๋‚ด๋ฒฝ(1.0B, ์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ) ๋ฐ ์™ธ๋ฒฝ(0.5B, ์ ๋ฒฝ๋Œ) ์‚ฌ์ด์— 20 mm ๋‘๊ป˜์˜ ์Šคํ‹ฐ๋กœํผ์„ ์‚ฝ์ž…ํ•˜์—ฌ ๋ฒฝ๋Œ์„ ์Œ“์•˜๋‹ค. ์‹คํ—˜์ฒด #3~#6์—๋Š” 1.0B ๋ฒฝ๋Œ์Œ“๊ธฐ(์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ)๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ๊ตญ๋‚ด ๋…ธํ›„ ๊ฑด๋ฌผ์˜ ์กฐ์ ์ƒํƒœ๋ฅผ ๋ชจ์‚ฌํ•˜๊ธฐ ์œ„ํ•˜์—ฌ, Fig. 4(b)์™€ ๊ฐ™์ด ์กฐ์  ์ค„๋ˆˆ์€ ๋ถˆ๋Ÿ‰ํ•œ ์ƒํƒœ๋กœ ์‹œ๊ณต๋˜์—ˆ๋‹ค. ์ฆ‰, ์ˆ˜ํ‰์ค„๋ˆˆ์€ ๋ฒฝ๋Œ ๋ฐ”๋‹ฅ๋ฉด์ ์˜ ์•ฝ 80~90 %์— ๋ชจ๋ฅดํƒ€๋ฅด๊ฐ€ ์ฑ„์›Œ์กŒ๊ณ , ์ˆ˜์ง์ค„๋ˆˆ์˜ ๊ฒฝ์šฐ ์ค„๋ˆˆ๋ชจ๋ฅดํƒ€๋ฅด๊ฐ€ ์ถฉ๋ถ„ํžˆ ๋‹ค์ ธ์ง€์ง€ ์•Š์€ ์ƒํƒœ๋กœ ์‹œ๊ณต๋˜์—ˆ๋‹ค.

Fig. 3 Configurations of masonry wall specimens before strengthening
../../Resources/KCI/JKCI.2023.35.4.397/fig3.png
Fig. 4 Fabrication of concrete pedestals and masonry walls
../../Resources/KCI/JKCI.2023.35.4.397/fig4.png
Table 1 Test variables

Specimen

Masonry wall

ECC jacket

Opening

#1 C-NJ

Cavity wall1)

1.5B2)

None

None

#2 C-FJ

Cavity wall1)

1.5B2)

Used

None

#3 S-NJ

Solid wall

1.0B2)

None

None

#4 S-FJ

Solid wall

1.0B2)

Used

None

#5 S-NJ-O

Solid wall

1.0B2)

None

Considered

#6 S-FJ-O

Solid wall

1.0B2)

Used

Considered

Notes: 1)The cavity was filled with 20-mm-thick polystyrene; 2)1.5B and 1.0B indicate three and two layers of wythe, respectively

2.2 ECC ์ž์ผ“ ๋ณด๊ฐ•

6๊ฐœ์˜ ์‹คํ—˜์ฒด ์ค‘ #2, #4 ๋ฐ #6 ์‹คํ—˜์ฒด์— ๋Œ€ํ•˜์—ฌ ECC ์ž์ผ“๋ณด๊ฐ•๊ณต๋ฒ•์„ ์ ์šฉํ•˜์˜€๋‹ค. Fig. 5๋Š” ์‹คํ—˜์ฒด๋ณ„ ECC ์ž์ผ“๋ณด๊ฐ• ๊ตฌ์กฐ์ƒ์„ธ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ECC ์ž์ผ“์˜ ๋‘๊ป˜๋Š” 40 mm์ด๊ณ , ECC ์ž์ผ“๊ณผ ์ƒํ•˜ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด๋ฅผ ์—ฐ๊ฒฐํ•˜๋Š” ์ƒํ•˜ ์•ต์ปค์ ‘ํ•ฉ๋ถ€๋Š” Fig. 6๊ณผ ๊ฐ™์ด ๋ณด๊ฐ•์•ต๊ธ€(๊ฐ•ํŒ๋‘๊ป˜ 10 mm), M16 ๋ถ€์ฐฉ์•ต์ปค(๊ฐ„๊ฒฉ 200 mm), D10 ๋ณด๊ฐ•์ฒ ๊ทผ(๊ฐ„๊ฒฉ 200 mm, ๊ธธ์ด 290 mm)์„ ์‚ฌ์šฉํ•˜์—ฌ ํ•˜์ค‘๊ฒฝ๋กœ๋ฅผ ๋ณด๊ฐ•ํ•˜์˜€๋‹ค. ECC ์ž์ผ“ ๋‚ด๋ถ€์—๋Š” ์กฐ์ ์•ต์ปค($\phi$4.5) ๋ฐ ์™€์ด์–ด๋ฉ”์‹œ(์ง๊ฒฝ 2 mm, ์ˆ˜์ง/์ˆ˜ํ‰ ๊ฐ„๊ฒฉ 50 mm)๋ฅผ ์„ค์น˜ํ•˜๊ณ , ์ด๋“ค์„ ํด๋ฆฝ์œผ๋กœ ๊ณ ์ •ํ•˜์˜€๋‹ค. ์‹คํ—˜์ฒด์˜ ECC ์ž์ผ“์€ Fig. 2์˜ ์‹œ๊ณต์ ˆ์ฐจ์— ๋”ฐ๋ผ ์‹œ๊ณต๋˜์—ˆ์œผ๋ฉฐ, ์‹คํ—˜์ฒด ์ œ์ž‘ ๊ณผ์ •์€ Fig. 7์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์ฐธ๊ณ ๋กœ, ์ฒ ๊ฑฐ ๋“ฑ ๋‚ด๋ถ€๊ณต์‚ฌ๊ฐ€ ์ตœ์†Œํ™”๋˜๋„๋ก ECC ์ž์ผ“์€ ๋ฐ”๊นฅ 1๋ฉด์—๋งŒ ์‹ค์น˜ํ•˜๋Š” ๋ณด๊ฐ•๋ฐฉ๋ฒ•์ด ๊ณ ๋ ค๋˜์—ˆ๊ณ , ์ž์ผ“๋‘๊ป˜๋Š” ์‹œ๊ณต๊ฐ€๋Šฅํ•œ ์ตœ์†Œ๋‘๊ป˜์ธ 40 mm๋กœ ์‹œ๊ณตํ•˜์˜€๋‹ค.

Fig. 5 Structural details of engineered cementitious composite (ECC) jacket for strengthening (specimens #2, #4, and #6 only)
../../Resources/KCI/JKCI.2023.35.4.397/fig5.png
Fig. 6 Anchor connection details of engineered cementitious composite (ECC) jacket
../../Resources/KCI/JKCI.2023.35.4.397/fig6.png
Fig. 7 Fabrication of engineered cementitious composite (ECC) jackets in specimens #2, #4, and #6
../../Resources/KCI/JKCI.2023.35.4.397/fig7.png

2.3 ์žฌ๋ฃŒ๊ฐ•๋„

Fig. 8(a)๋Š” ์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ(190 mmร—90 mmร—57 mm)์„ 3๋‹จ์œผ๋กœ ์Œ“์€ ์กฐ์ ํ”„๋ฆฌ์ฆ˜(masonry prism)์˜ ์••์ถ•์‹œํ—˜([4]ASTM C1314) ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ํ”„๋ฆฌ์ฆ˜ ์••์ถ•์‹œํ—˜์œผ๋กœ ๊ตฌํ•œ ์กฐ์ ๋ฒฝ์ฒด์˜ ํ‰๊ท  ์••์ถ•๊ฐ•๋„ ๋ฐ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ฐ๊ฐ $f_{m}'$=7.56 MPa ๋ฐ $E_{m}$=1,820 MPa์ด๋‹ค. ์••์ถ•ํŒŒ๊ดด๋Š” Fig. 8(a)์™€ ๊ฐ™์ด ํ•œ์ชฝ ๋‹จ๋ถ€์—์„œ ์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ์ด ์ˆ˜์ง์œผ๋กœ ์ชผ๊ฐœ์ง€๋Š” ํ• ๋ ฌํŒŒ๊ดด ์–‘์ƒ์„ ๋ณด์˜€๋‹ค. ์ธก์ •๋œ ์กฐ์ ๋ฒฝ์ฒด์˜ ์••์ถ•๊ฐ•๋„($f_{m}'$=7.56 MPa) ๋ฐ ํƒ„์„ฑ๊ณ„์ˆ˜($E_{m}$=1,820 MPa)๋Š” ๋‚ด์ง„์„ฑ๋Šฅํ‰๊ฐ€์š”๋ น(KISC 2013)์—์„œ ๊ทœ์ •ํ•˜๋Š” ์„ค๊ณ„๊ธฐ์ค€์••์ถ•๊ฐ•๋„(=6.2 MPa, ์กฐ์ ์ƒํƒœ โ€˜์–‘ํ˜ธโ€™) ๋ฐ ์„ค๊ณ„๊ธฐ์ค€๊ฐ’(=200$f_{m}'$=1,512 MPa)๋ณด๋‹ค ์•ฝ 20 % ์ •๋„ ํฐ ๊ฐ’์ด์—ˆ๋‹ค. Fig. 8(a)์˜ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„์—์„œ ๋ณด๋“ฏ์ด, ์กฐ์ ํ”„๋ฆฌ์ฆ˜์˜ ์ตœ๋Œ€์••์ถ•์‘๋ ฅ์€ ์•ฝ 0.005 mm/mm ๊ทผ์ฒ˜์—์„œ ๋ฐœ์ƒํ•˜์˜€๋Š”๋ฐ, ์ด๋Š” ๊ธฐ์กด ์—ฐ๊ตฌ(Lee et al. 2021; Kim et al. 2022)์—์„œ ๋ณด๊ณ ๋œ ์žฌ๋ฃŒ์‹œํ—˜ ๊ฒฐ๊ณผ์™€ ์œ ์‚ฌํ•˜๋‹ค. ์ด์ฒ˜๋Ÿผ ์กฐ์ ํ”„๋ฆฌ์ฆ˜์€ ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ ๋Œ€๋น„ ํฐ ์••์ถ•๋ณ€ํ˜•๋ฅ ์—์„œ ์ตœ๋Œ€์‘๋ ฅ์— ๋„๋‹ฌํ•˜์˜€๋‹ค. Fig. 8(b)๋Š” ์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ 6๊ฐœ๋ฅผ ์Œ“์•„ ์ œ์ž‘ํ•œ ์กฐ์ ํ”„๋ฆฌ์ฆ˜์˜ ๋ฉด์™ธ ํœจ์‹คํ—˜ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ฃผ๋Š”๋ฐ, ๊ฒฝ๊ฐ„ ์ค‘์•™์—์„œ ๋ฒฝ๋Œ๊ณผ ๋ชจ๋ฅดํƒ€๋ฅด ์‚ฌ์ด ์ ‘ํ•ฉ๋ฉด์—์„œ ์ธ์žฅํŒŒ๋‹จ์ด ๋ฐœ์ƒํ•˜์˜€๋‹ค. ์ด๋กœ๋ถ€ํ„ฐ ์กฐ์ ๋ฒฝ์˜ ํ‰๊ท  ์ค„๋ˆˆ์ธ์žฅํŒŒ๋‹จ๊ฐ•๋„($f_{bjt}$)๋Š” 0.18 MPa๋กœ ์กฐ์‚ฌ๋˜์—ˆ๋‹ค. ๊ทธ ์™ธ ์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ ๋ฐ ์ค„๋ˆˆ๋ชจ๋ฅดํƒ€๋ฅด์— ๋Œ€ํ•ด์„œ๋„ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์žฌ๋ฃŒ์‹œํ—˜์„ ๋ณ„๋„๋กœ ์ง„ํ–‰ํ•˜์˜€๋‹ค. KS F 4004(KATS 2018)์— ๋”ฐ๋ผ ์‹คํ—˜๋œ ์‹œ๋ฉ˜ํŠธ๋ฒฝ๋Œ์˜ ํ‰๊ท  ์••์ถ•๊ฐ•๋„ ๋ฐ ํœจ์ธ์žฅ๊ฐ•๋„๋Š” ๊ฐ๊ฐ 10.7 MPa ๋ฐ 1.35 MPa๋กœ ์กฐ์‚ฌ๋˜์—ˆ๋‹ค. ์ค„๋ˆˆ๋ชจ๋ฅดํƒ€๋ฅด์— ๋Œ€ํ•ด์„œ๋Š” KS F 2405 KATS 2017)์— ๋”ฐ๋ผ ์ง๊ฒฝ 100 mm, ๊ธธ์ด 200 mm์˜ ์›์ฃผํ˜• ๊ณต์‹œ์ฒด๋ฅผ ์ œ์ž‘ํ•˜์—ฌ ์••์ถ•์‹œํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€์œผ๋ฉฐ(Fig. 8(c) ์ฐธ์กฐ), ํ‰๊ท  ์••์ถ•๊ฐ•๋„ ๋ฐ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ฐ๊ฐ 17.0 MPa ๋ฐ 14,500 MPa๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

Fig. 8(d)๋Š” 3๋‹จ์œผ๋กœ ์Œ“์€ ์กฐ์ ํ”„๋ฆฌ์ฆ˜์— ๋Œ€ํ•œ ์ค„๋ˆˆ์ „๋‹จ์‹œํ—˜ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. BS EN 1052-3(BSI 2002) ์ค„๋ˆˆ์ „๋‹จ์‹œํ—˜์€ ์ค„๋ˆˆ ์ ‘ํ•ฉ๋ฉด์— ์ž‘์šฉํ•˜๋Š” ์—ฐ์ง์‘๋ ฅ ํฌ๊ธฐ๋ฅผ $\sigma$=0.3, 0.6, ๋ฐ 0.9 MPa๋กœ ์ฆ๊ฐ€์‹œํ‚ค๋ฉฐ ์ง„ํ–‰ํ•˜์˜€๊ณ , ๊ฐ ์—ฐ์ง์‘๋ ฅ์— ๋Œ€ํ•˜์—ฌ 2๋ฒˆ์˜ ์‹คํ—˜์„ ๋ฐ˜๋ณตํ•˜์˜€๋‹ค. Fig. 8(d2)์—์„œ ์ค„๋ˆˆ์ „๋‹จ๊ฑฐ๋™์€ ์ตœ๋Œ€์‘๋ ฅ์— ๋„๋‹ฌํ•œ ์ดํ›„ ์‘๋ ฅ์ด ๊ฐ์†Œํ•˜์˜€์ง€๋งŒ ์ดํ›„ ์ผ์ • ์ˆ˜์ค€์˜ ์ž”๋ฅ˜์‘๋ ฅ์„ ์œ ์ง€ํ•˜์˜€๋‹ค. ์ค„๋ˆˆ์ „๋‹จํŒŒ๊ดด์— ์˜ํ•œ ์ตœ๋Œ€์‘๋ ฅ ๋ฐ ์ž”๋ฅ˜์‘๋ ฅ์€ ์ค„๋ˆˆ ์ ‘ํ•ฉ๋ฉด์˜ ์—ฐ์ง์‘๋ ฅ($\sigma$)์ด ์ปค์งˆ์ˆ˜๋ก ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ตœ๋Œ€์‘๋ ฅ์„ ๊ธฐ์ค€์œผ๋กœ ์‚ฐ์ •ํ•œ ์กฐ์  ๊ฐ€๋กœ์ค„๋ˆˆ(bed joint)์˜ ๋งˆ์ฐฐ๊ณ„์ˆ˜ ๋ฐ ์ ์ฐฉ๋ ฅ์€ ๊ฐ๊ฐ $\mu$=0.683(๋˜๋Š” ๋งˆ์ฐฐ๊ฐ $\phi$= 34.3ยฐ) ๋ฐ $c$=0.847 MPa๋กœ ํ‰๊ฐ€๋˜์—ˆ๋‹ค(Fig. 8(d3) ์ฐธ์กฐ). ์ฐธ๊ณ ๋กœ, ๋ชจ๋ฅดํƒ€๋ฅด ์ ‘ํ•ฉ๋ฉด์—์„œ ๋ฏธ๋„๋Ÿผ๋ณ€ํ˜•์ด ๋ฐœ์ƒํ•œ ์ดํ›„์˜ ์ค„๋ˆˆ ์ž”๋ฅ˜์ „๋‹จ์‘๋ ฅ์€ $\tau$=0.5-0.8 MPa ์ˆ˜์ค€์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค(Fig. 8(d2) ์ฐธ์กฐ).

ECC ์ž์ผ“์—๋Š” PVA(poly-vinyl alcohol) ์„ฌ์œ ๊ฐ€ ์ฒด์ ๋น„ 2.0 %๋กœ ๋ฐฐํ•ฉ๋œ ์„ฌ์œ ๋ณด๊ฐ•๋ชจ๋ฅดํƒ€๋ฅด๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ์›์ฃผํ˜• ๊ณต์‹œ์ฒด(์ง๊ฒฝ 100 mm, ๊ธธ์ด 200 mm, KS F 2405)์— ๋Œ€ํ•˜์—ฌ ํ‰๊ท  ์••์ถ•๊ฐ•๋„ ๋ฐ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ฐ๊ฐ 44.0 MPa ๋ฐ 19,200 MPa๋กœ ์กฐ์‚ฌ๋˜์—ˆ๊ณ  ์•ฝ 0.0031 mm/mm์˜ ๋ณ€ํ˜•๋ฅ ์—์„œ ์ตœ๋Œ€์••์ถ•์‘๋ ฅ์— ๋„๋‹ฌํ•˜์˜€๋‹ค. ECC ์ž์ผ“์˜ ์ธ์žฅํŠน์„ฑ์€ ์ง์ ‘์ธ์žฅ์‹œํ—˜์„ ํ†ตํ•ด ๊ณ„์ธกํ•˜์˜€๋‹ค(JSCE 1999) ์žฌ๋ น 28์ผ ๊ธฐ์ค€ ECC ๋ชจ๋ฅดํƒ€๋ฅด๋Š” Fig. 9(a)์™€ ๊ฐ™์ด 3.1 MPa์—์„œ ๊ท ์—ด์„ ์‹œ์ž‘ํ•˜์˜€๊ณ  ๋ณ€ํ˜•๋ฅ  3 %๊นŒ์ง€ ์•ฝ 3.5 MPa์˜ ์ธ์žฅ๊ฐ•๋„๋ฅผ ์œ ์ง€ํ•˜์˜€๋‹ค. Fig. 9(c)๋Š” ์ฒ ์„ (์ง๊ฒฝ 1.95 mm, ํ•ญ๋ณต๊ฐ•๋„ 425 MPa, ๊ทนํ•œ๊ฐ•๋„ 517 MPa)๋ฅผ ํฌํ•จํ•œ ECC ์ž์ผ“์˜ ์ธ์žฅํŠน์„ฑ์„ ๋ณด์—ฌ์ฃผ๋Š”๋ฐ, Fig. 9(a)์™€ ๋น„๊ตํ•˜์—ฌ ์ดˆ๊ธฐ๊ท ์—ด์ด ์‹œ์ž‘๋˜๋Š” ์‘๋ ฅ์€ ๋น„์Šทํ•˜์ง€๋งŒ ์ดํ›„ ๊ฐ•๋„ ๋ฐ ์—ฐ์„ฑ์ด ํฌ๊ฒŒ ๊ฐœ์„ ๋œ ๊ฑฐ๋™์„ ๋ณด์˜€๋‹ค. ์ฐธ๊ณ ๋กœ, Fig. 9(b)๋Š” ์ง๊ฒฝ 1 mm ์ฒ ์„  2๊ฐ€๋‹ฅ์ด ํ•จ์œ ๋œ ECC ์ž์ผ“์˜ ์ธ์žฅํŠน์„ฑ์„ ๋ณด์—ฌ์ฃผ๋Š”๋ฐ, ์•ฝ 3.1 MPa์—์„œ ์ดˆ๊ธฐ๊ท ์—ด, 0.8 % ๋ณ€ํ˜•๋ฅ ์—์„œ ์ฒ ์„  ํ•ญ๋ณต, ์ตœ์ข…์ ์œผ๋กœ 2 % ๋ณ€ํ˜•๋ฅ ์—์„œ ํŒŒ๋‹จ๋˜์—ˆ๋‹ค.

์กฐ์ ๋ฒฝ์ฒด ์ƒํ•˜๋ถ€ ๋ณด์— ์‚ฌ์šฉ๋œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„(KS F 2405)๋Š” 31.6 MPa, ๋ณด๊ฐ•์ฒ ๊ทผ D10 ๋ฐ D19์˜ ํ•ญ๋ณต๊ฐ•๋„๋Š” ๊ฐ๊ฐ 481 MPa ๋ฐ 447 MPa๋กœ ์กฐ์‚ฌ๋˜์—ˆ๋‹ค.

Fig. 8 Material strength tests of masonry
../../Resources/KCI/JKCI.2023.35.4.397/fig8.png
Fig. 9 Tensile properties of engineered cementitious composite (ECC) jacket
../../Resources/KCI/JKCI.2023.35.4.397/fig9.png

2.4 ์žฌํ•˜๊ณ„ํš

ํšกํ•˜์ค‘ ๋ฐ˜๋ณต๊ฐ€๋ ฅ์„ ์œ„ํ•œ ์‹คํ—˜์…‹ํŒ…์„ Fig. 10(a)์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์ž‘์šฉํ•˜์ค‘์œผ๋กœ๋Š” ์กฐ์ ๋ฒฝ์— ์ž‘์šฉํ•˜๋Š” ์••์ถ•ํ•˜์ค‘๊ณผ ํšกํ•˜์ค‘์„ ๊ณ ๋ คํ•˜์˜€๋‹ค. ์ƒ๋ถ€ ๊ฐ•์žฌ๋ณด(์ค‘๋Ÿ‰ 19.5 kN) ์œ„์— ์„ค์น˜๋œ ์ˆ˜์ง๋ฐฉํ–ฅ ์•ก์ถ”์—์ดํ„ฐ๋กœ๋ถ€ํ„ฐ ์ผ์ •ํ•œ ์ดˆ๊ธฐ ์••์ถ•ํ•˜์ค‘ 120 kN์„ ๊ฐ€ํ•œ ์ƒํƒœ์—์„œ ์ˆ˜ํ‰๋ฐฉํ–ฅ ์•ก์ถ”์—์ดํ„ฐ์˜ ํšก๋ณ€์œ„๋ฅผ ์ œ์–ดํ•˜๋ฉฐ ํšกํ•˜์ค‘์„ ๊ฐ€ํ•˜์˜€๋‹ค. Fig. 10(b)์™€ ๊ฐ™์ด ํšก๋ณ€์œ„๋น„(=๊ฐ€๋ ฅ์  ํšก๋ณ€์œ„๋ฅผ ๋†’์ด 1,950 mm๋กœ ๋‚˜๋ˆˆ ๊ฐ’) 0.31 %๊นŒ์ง€๋Š” 3ํšŒ ๋ฐ˜๋ณต๊ฐ€๋ ฅํ•˜์˜€๊ณ , 0.58 % ์ดํ›„๋กœ๋Š” 2ํšŒ ๋ฐ˜๋ณต๊ฐ€๋ ฅํ•˜์˜€๋‹ค. ์•ก์ถ”์—์ดํ„ฐ์— ์—ฐ๊ฒฐ๋œ ๊ฐ•์žฌ์ง€๊ทธ๋ฅผ ์ง์ ‘ ํšก์ง€์ง€ํ•จ์œผ๋กœ์จ ์‹คํ—˜ ์ค‘ ์กฐ์ ๋ฒฝ์ฒด์— ๋ฉด์™ธ๋ณ€ํ˜•์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š๋„๋ก ํ•˜์˜€๋‹ค(Fig. 10(a) ์ฐธ์กฐ).

์ฐธ๊ณ ๋กœ, ์กฐ์ ๋ฒฝ์ฒด์—๋Š” ์ˆ˜์ง ์•ก์ถ”์—์ดํ„ฐ์— ์˜ํ•œ ์••์ถ•ํ•˜์ค‘(120 kN) ์ด์™ธ์—๋„ ์ฝ˜ํฌ๋ฆฌํŠธ ์ƒ๋ถ€๋ณด(4.2 kN) ๋ฐ ๊ฐ•์žฌ๋ณด(19.5 kN)์˜ ์ž์ค‘์ด ์••์ถ•ํ•˜์ค‘์œผ๋กœ ์ž‘์šฉ๋˜์—ˆ๋‹ค($N$=143.7 kN). ๋”ฐ๋ผ์„œ ํšกํ•˜์ค‘์„ ๊ฐ€ํ•˜๊ธฐ ์ด์ „ ๋ฒฝ์ฒด์— ์„ ์žฌํ•˜๋œ ์••์ถ•์‘๋ ฅ($f_{a}$, ECC ์ž์ผ“์„ ์ œ์™ธํ•œ ์กฐ์ ๋‹จ๋ฉด๋งŒ์˜ ๋ฉด์ ์œผ๋กœ ์‚ฐ์ •)์˜ ํฌ๊ธฐ๋Š” ์‹คํ—˜์ฒด #1 ๋ฐ #2์—์„œ 0.24 MPa(๊ตญ๋‚ด 2์ธต ์กฐ์ ๊ฑด๋ฌผ ์ถ•์‘๋ ฅ ์ˆ˜์ค€, Kang et al. 2010), ์‹คํ—˜์ฒด #3~#6์—์„œ 0.36 MPa์ด์—ˆ๋‹ค.

Fig. 10 Loading plan
../../Resources/KCI/JKCI.2023.35.4.397/fig10.png

3. ์‹คํ—˜ ๊ฒฐ๊ณผ

3.1 ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์กฐ์ ์‹คํ—˜์ฒด #1-#4

Fig. 11(a) and 11(b)๋Š” ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์กฐ์  ์‹คํ—˜์ฒด #1~#4์˜ ํ•˜์ค‘-๋ณ€์œ„($P$-$\Delta$) ๊ด€๊ณ„์™€ ์ฃผ์š” ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ECC ์ž์ผ“์˜ ๋ณด๊ฐ• ํšจ๊ณผ๋ฅผ ๋ช…ํ™•ํžˆ ์‚ดํŽด๋ณผ ์ˆ˜ ์žˆ๋„๋ก, ์กฐ์ ์ƒ์„ธ๊ฐ€ ๋™์ผํ•œ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์‹คํ—˜์ฒด์˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ๋Œ€๋น„ํ•˜์—ฌ ๋‚˜ํƒ€๋ƒˆ๋‹ค. ํ•˜์ค‘ $P$๋Š” ์ˆ˜ํ‰ ์•ก์ถ”์—์ดํ„ฐ์˜ ํ•˜์ค‘์ด๊ณ , ๋ณ€์œ„ $\Delta$๋Š” ๊ฐ€๋ ฅ์ ์—์„œ ๊ณ„์ธก๋œ ํšก๋ณ€์œ„๋ฅผ ๊ฐ€๋ฆฌํ‚จ๋‹ค. ํšก๋ณ€์œ„๋น„(lateral drift ratio)๋Š” ํšก๋ณ€์œ„ $\Delta$๋ฅผ ๊ฐ€๋ ฅ์  ๋†’์ด 1,950 mm๋กœ ๋‚˜๋ˆˆ ๊ฐ’์ด๋‹ค. ์ฐธ๊ณ ๋กœ, ์กฐ์ ๋ฒฝ์ฒด์˜ ์ฃผ๋œ ๋ณ€ํ˜•๋ชจ๋“œ๋Š” ๊ฐ•์ฒดํšŒ์ „์œผ๋กœ ์กฐ์ ๋ฒฝ์ฒด๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๊ทธ ์œ„์˜ ๊ฐ•์žฌ์ง€๊ทธ์—์„œ๋„ ํšŒ์ „์— ์˜ํ•œ ํšก๋ณ€์œ„๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ๋”ฐ๋ผ์„œ ํšก๋ณ€์œ„๋น„ ์‚ฐ์ •์‹œ ์กฐ์ ๋ฒฝ์ฒด ๋ฐ”๋‹ฅ๋ถ€ํ„ฐ ๊ฐ€๋ ฅ์ ๊นŒ์ง€์˜ ๋†’์ด(=1,950 mm)๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค(Fig. 10(a) ์ฐธ์กฐ).

๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์‹คํ—˜์ฒด #1~#4๋Š” Fig. 11(a) and 11(b)์— ๋‚˜ํƒ€๋‚ธ ๋ฐ”์™€ ๊ฐ™์ด ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์˜ ์ „ํ˜•์ ์ธ ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„์™€ ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๋ณด์˜€๋‹ค.

Fig. 11 Lateral load-deformation relationships and failure modes
../../Resources/KCI/JKCI.2023.35.4.397/fig11.png

3.1.1 ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„

๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด์ธ #1 C-NJ ๋ฐ #3 S-NJ๋Š” Fig. 11(a1) and 11 (b1)์— ๋‚˜ํƒ€๋‚ธ ๋ฐ”์™€ ๊ฐ™์ด ์ •๋ฐฉํ–ฅ ๋ฐ ๋ถ€๋ฐฉํ–ฅ ํšกํ•˜์ค‘์— ๋Œ€ํ•˜์—ฌ ๋Œ€์นญ์— ๊ฐ€๊นŒ์šด ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„๋ฅผ ๋ณด์˜€๋‹ค. ํšก๋ณ€์œ„๋น„ $\pm$0.58 %์—์„œ ์ตœ๋Œ€ํ•˜์ค‘์— ๋„๋‹ฌํ•˜์˜€๊ณ , ์ดํ›„ ํšก๋ณ€์œ„๋น„ $\pm$2.31 %๊นŒ์ง€ ๊ฐ•๋„๊ฐ€ ์™„๋งŒํ•˜๊ฒŒ ๊ฐ์†Œํ•˜๋Š” ๊ฑฐ๋™์„ ๋ณด์˜€๋‹ค. ์‹คํ—˜์ฒด #1 ๋ฐ #3์—์„œ ์ •๋ฐฉํ–ฅ ์ตœ๋Œ€ํ•˜์ค‘์€ ๊ฐ๊ฐ $P_{u}$=+74.3 kN ๋ฐ +77.0 kN์ด์—ˆ๊ณ , ๋ถ€๋ฐฉํ–ฅ ์ตœ๋Œ€ํ•˜์ค‘์€ $P_{u}$=-63.2 kN ๋ฐ -63.7 kN์œผ๋กœ ์ •๋ฐฉํ–ฅ ์ตœ๋Œ€ํ•˜์ค‘๋ณด๋‹ค ์กฐ๊ธˆ ์ž‘์•˜๋‹ค. ์ตœ๋Œ€ํ•˜์ค‘ ์ดํ›„ ํšก๋ณ€์œ„๋น„ 2.31 %์— ๋„๋‹ฌ ์‹œ๊นŒ์ง€ ์•ฝ 30 % ๊ฐ•๋„๊ฐ€ ๊ฐ์†Œํ•˜์˜€๋‹ค. ๋‘ ์‹คํ—˜์ฒด ๋ชจ๋‘ ๋ฐ˜๋ณตํ•˜์ค‘์— ๋Œ€ํ•˜์—ฌ ์—๋„ˆ์ง€์†Œ์‚ฐ์„ฑ๋Šฅ์ด ์ œํ•œ์ ์ธ ์ด๋ ฅํ˜•์ƒ์„ ๋ณด์˜€๋‹ค.

ECC ์ž์ผ“์œผ๋กœ ๋ณด๊ฐ•๋œ #2 C-FJ ๋ฐ #4 S-FJ ๋˜ํ•œ ์ •๋ฐฉํ–ฅ ๋ฐ ๋ถ€๋ฐฉํ–ฅ ๋Œ€์นญ์˜ ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„๋ฅผ ๋ณด์˜€๋‹ค(Fig. 11(a1) and 11(b1) ์ฐธ์กฐ). ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด์™€ ์œ ์‚ฌํ•˜๊ฒŒ ํšก๋ณ€์œ„๋น„ $\pm$0.58 %์—์„œ ์ตœ๋Œ€ํ•˜์ค‘์— ๋„๋‹ฌํ•˜์˜€์œผ๋ฉฐ ์ดํ›„ ์ ์ง„์ ์ธ ๊ฐ•๋„์ €ํ•˜๋ฅผ ์ˆ˜๋ฐ˜ํ•œ ์—ฐ์„ฑ๊ฑฐ๋™์„ ๋ณด์˜€๊ณ , ๋ฐ˜๋ณตํ•˜์ค‘์— ๋Œ€ํ•˜์—ฌ ์—๋„ˆ์ง€์†Œ์‚ฐ๋Šฅ๋ ฅ์ด ๊ฐœ์„ ๋œ ์ด๋ ฅํ˜•์ƒ์„ ๋ณด์˜€๋‹ค. ํ•˜์ง€๋งŒ, ์ตœ๋Œ€ํ•˜์ค‘์€ ์‹คํ—˜์ฒด #2์—์„œ $P_{u}$=+154 kN ๋ฐ -153 kN, ์‹คํ—˜์ฒด #4์—์„œ $P_{u}$=+162 kN ๋ฐ -165 kN์œผ๋กœ ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด ๋Œ€๋น„ ์•ฝ 2๋ฐฐ ์ˆ˜์ค€์œผ๋กœ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ฃผ๊ธฐ๊ฑฐ๋™์— ์˜ํ•œ ์—๋„ˆ์ง€์†Œ์‚ฐ(์ฆ‰, ์ด๋ ฅ๊ณก์„  ๋ฉด์ ) ๋˜ํ•œ ๊ฐ•๋„ ์ฆ๊ฐ€์— ๋น„๋ก€ํ•˜์—ฌ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์˜€๋‹ค.

3.1.2 ํŒŒ๊ดด๋ชจ๋“œ

๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #1 ๋ฐ #3์€ Fig. 11(a2) and 11(b2)์—์„œ ๋ณด๋“ฏ์ด ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์— ์˜ํ•ด ๋ฒฝ์ฒด ํ•˜๋ถ€ ์ธ์žฅ์ธก์—์„œ ์ˆ˜ํ‰์œผ๋กœ ์ค„๋ˆˆ์ธ์žฅํŒŒ๊ดด(joint tensile failure)๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. #1์—์„œ๋Š” ์ค„๋ˆˆ์ธ์žฅํŒŒ๊ดด๊ฐ€ ์กฐ์ ๊ณผ ํ•˜๋ถ€ RC๋ณด ์‚ฌ์ด ์ ‘ํ•ฉ๋ฉด์—์„œ ๋ฐœ์ƒํ•˜์˜€๊ณ , #3์—์„œ๋Š” ์กฐ์ ๋ฒฝ ๋‚ด๋ถ€์˜ ์ˆ˜ํ‰์ค„๋ˆˆ์—์„œ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ๋ฒฝ์ฒด ํ•˜๋ถ€์˜ ์••์ถ•๋‹จ๋ถ€์—์„œ๋Š” ์กฐ์ ๋‹จ๋ถ€์••๊ดด(masonry toe crushing)๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ์ด๋Ÿฌํ•œ ์กฐ์ ๋‹จ๋ถ€์••๊ดด๋Š” ํšก๋ณ€์œ„๋น„ 1.54 %์—์„œ ์‹œ์ž‘๋˜์—ˆ์œผ๋ฉฐ ์ดํ›„ ์ฃผ๊ธฐ๊ฑฐ๋™์ด ๋ฐ˜๋ณต๋จ์— ๋”ฐ๋ผ ๋ฒฝ ๋‚ด๋ถ€๋กœ ์ ์ฐจ ํ™•์‚ฐ๋˜์—ˆ๋‹ค. ๊ทธ ์™ธ์—๋„ ์กฐ์ ๋ฒฝ ํ•˜๋ถ€์˜ RC๋ณด์—์„œ๋„ ํšก๋ณ€์œ„๋น„ 0.77 %์—์„œ ์ˆ˜์ง๊ท ์—ด์ด ์‹œ์ž‘๋˜์—ˆ์œผ๋ฉฐ ๊ฒฐ๊ตญ ํšก๋ณ€์œ„๋น„ 2.31 %์—์„œ ์ฝ˜ํฌ๋ฆฌํŠธ ํŒŒ์—ด(concrete spalling)๋กœ ๋ฐœ์ „๋˜์—ˆ๋‹ค.

ECC ์ž์ผ“์œผ๋กœ ๋ณด๊ฐ•๋œ #2 ๋ฐ #4์—์„œ๋„ Fig. 11(a3) and 11(b3)์—์„œ ๋ณด๋“ฏ์ด ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด์™€ ์œ ์‚ฌํ•œ ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๋ณด์˜€๋‹ค. ์กฐ์ ๋ฒฝ์ฒด์—์„œ๋Š” ์ธ์žฅ์ธก ๋ฐ ์••์ถ•์ธก์—์„œ ๊ฐ๊ฐ ์ค„๋ˆˆ์ธ์žฅํŒŒ๊ดด์™€ ๋‹จ๋ถ€์••๊ดด๊ฐ€ ๊ด€์ฐฐ๋˜์—ˆ๋‹ค. ECC ์ž์ผ“์—์„œ๋Š” ์ธ์žฅ์ธก์—์„œ ๊ฐ•์ฒดํšŒ์ „์— ์˜ํ•œ ์ˆ˜ํ‰๊ท ์—ด์ด ํ•˜๋ถ€์—์„œ ๋ฐœ์ƒํ•˜์˜€์œผ๋‚˜, ์‹คํ—˜์ด ์ข…๋ฃŒ๋  ๋•Œ๊นŒ์ง€ ๊ฑฐ์˜ ์˜จ์ „ํ•œ ์ƒํƒœ๋ฅผ ์œ ์ง€ํ•˜์˜€๋‹ค. ๊ทธ ๋Œ€์‹  ECC ์ž์ผ“์„ ์—ฐ๊ฒฐํ•˜๋Š” ํ•˜๋ถ€ ์•ต์ปค(M16) ์ ‘ํ•ฉ๋ถ€์—์„œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ท ์—ด์ด ํฌ๊ฒŒ ๋ฐœ์ƒํ•˜์—ฌ ๊ฒฐ๊ตญ ํšก๋ณ€์œ„๋น„ 2.31 %์—์„œ ํŒŒ๊ดด๋˜์—ˆ๋‹ค. ํŠนํžˆ, ECC ์ž์ผ“์—์„œ ์ˆ˜ํ‰๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์œ„์น˜(์ฆ‰, ๋ฒฝ์ฒด ๋ฐ”๋‹ฅ)๋Š” ์™€์ด์–ด๋ฉ”์‰ฌ๊ฐ€ ๋ฐฐ์น˜๋˜์ง€ ์•Š์€ ์•ต์ปค ์ ‘ํ•ฉ๋ถ€ ์ฃผ๋ณ€์ด์—ˆ๋Š”๋ฐ(Fig. 6 ์ฐธ์กฐ), ์ด๋Š” ์‹คํ—˜์ฒด #2 ๋ฐ #4์—์„œ ๊ฐ•์ฒดํšŒ์ „ํŒŒ๊ดด์— ๋Œ€ํ•œ ๋ณด๊ฐ• ํšจ๊ณผ๊ฐ€ ์™€์ด์–ด๋ฉ”์‰ฌ๋ณด๋‹ค๋Š” ECC ์ž์ผ“์— ์˜ํ•œ ๊ฒƒ์ž„์„ ์˜๋ฏธํ•œ๋‹ค.

3.2 ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ์กฐ์ ์‹คํ—˜์ฒด #5 ๋ฐ #6

์‹คํ—˜์ฒด #5 ๋ฐ #6์€ Fig. 11(c)์—์„œ ๋ณด๋Š” ๋ฐ”์™€ ๊ฐ™์ด ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„ ๋ฐ ํŒŒ๊ดด๋ชจ๋“œ๊ฐ€ ์กฐ์ ๋ฒฝ ๋‚ด๋ถ€ ๊ฐœ๊ตฌ๋ถ€์— ์˜ํ•ด ์˜ํ–ฅ์„ ๋ฐ›์•˜๋‹ค.

3.2.1 ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„

๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #5 S-NJ-O๋Š” Fig. 11(c1)์— ๋‚˜ํƒ€๋‚ธ ๋ฐ”์™€ ๊ฐ™์ด ์ •๋ฐฉํ–ฅ ๋ฐ ๋ถ€๋ฐฉํ–ฅ ํšกํ•˜์ค‘์— ๋Œ€ํ•˜์—ฌ ๋น„๋Œ€์นญ์˜ ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„๋ฅผ ๋ณด์˜€๋‹ค. ํฐ ๋ฒฝ๊ธฐ๋‘ฅ WP1์ด ์ธ์žฅ์ธก์— ๋†“์ด๋Š” ์ •๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ ์ตœ๋Œ€ํ•˜์ค‘์€ $P_{u}$=+74.5 kN์ด์—ˆ๊ณ , ์ž‘์€ ๋ฒฝ๊ธฐ๋‘ฅ WP2๊ฐ€ ์ธ์žฅ์— ์ €ํ•ญํ•˜๋Š” ๋ถ€๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ๋Š” ์ตœ๋Œ€ํ•˜์ค‘์ด $P_{u}$=-54.5 kN์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. ๋ณ€ํ˜•๋Šฅ๋ ฅ์€ ํšก๋ณ€์œ„๋น„ 0.58 %๋กœ์„œ, ํšก๋ณ€์œ„๋น„ +0.77 %๋กœ ์žฌํ•˜ํ•˜๋Š” ์ค‘์— ์ทจ์„ฑํŒŒ๊ดด๋ฅผ ๋ณด์˜€๋‹ค. ๋ฐ˜๋ณตํ•˜์ค‘์— ๋Œ€ํ•œ ์ด๋ ฅํ˜•์ƒ์€ ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์˜ ์ „ํ˜•์ ์ธ ์ด๋ ฅํ˜•์ƒ๊ณผ ์œ ์‚ฌํ•˜์˜€๊ณ , ์ฃผ๊ธฐ๊ฑฐ๋™์— ์˜ํ•œ ์—๋„ˆ์ง€์†Œ์‚ฐ์€ ์ œํ•œ์ ์ด์—ˆ๋‹ค. ์ฐธ๊ณ ๋กœ, ์ธ์žฅ๊ณผ ์••์ถ• ์žฌ๋ฃŒํŠน์„ฑ์ด ๋‹ค๋ฅธ ์กฐ์ ๋ฒฝ์ฒด์—์„œ ์ธ์žฅ์˜์—ญ๊ณผ ์••์ถ•์˜์—ญ์€ ๊ทธ ํฌ๊ธฐ๊ฐ€ ๋‹ค๋ฅด๋ฏ€๋กœ ๊ฐœ๊ตฌ๋ถ€ ์œ„์น˜์— ์˜ํ•ด ์กฐ์ ๋ฒฝ์ฒด์˜ ๊ฑฐ๋™์ด ๋‹ฌ๋ผ์ง„๋‹ค. ์ด๋Ÿฌํ•œ ๋งฅ๋ฝ์—์„œ ์‹คํ—˜์ฒด #5์—์„œ ์ •๋ฐฉํ–ฅ ๋ฐ ๋ถ€๋ฐฉํ–ฅ์˜ ํŒŒ๊ดด๋ชจ๋“œ, ๊ฐ•๋„ ๋ฐ ๊ฐ•์„ฑ์ด ๋‹ฌ๋ž๋˜ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

ECC ์ž์ผ“ ๋ณด๊ฐ• ์‹คํ—˜์ฒด #6 S-FJ-O ๋˜ํ•œ ์ •๋ฐฉํ–ฅ ๋ฐ ๋ถ€๋ฐฉํ–ฅ ํšกํ•˜์ค‘์— ๋Œ€ํ•˜์—ฌ ๋น„๋Œ€์นญ์˜ ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„๋ฅผ ๋ณด์˜€๋‹ค(Fig. 11(c1) ์ฐธ์กฐ). ์ •๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ ์ตœ๋Œ€ํ•˜์ค‘์ด $P_{u}$=+158 kN๊นŒ์ง€ ๋ฐœํœ˜๋˜์—ˆ๊ณ  ํšก๋ณ€์œ„๋น„ 1.54 %๊นŒ์ง€ ๊ฐ•๋„๊ฐ€ ์œ ์ง€๋˜๋Š” ์—ฐ์„ฑ๊ฑฐ๋™์„ ๋ณด์˜€๋‹ค. ๋ฐ˜๋ฉด ๋ถ€๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ๋Š” ํšก๋ณ€์œ„๋น„ -0.4 %์—์„œ ์ตœ๋Œ€ํ•˜์ค‘ $P_{u}$=-126 kN์— ๋„๋‹ฌํ•˜์˜€๊ณ  ์ดํ›„ ๊ฐ•๋„๊ฐ€ ๊ธ‰๊ฒฉํžˆ ์ €ํ•˜๋˜์—ˆ๋‹ค. ๋ฐ˜๋ณตํ•˜์ค‘์— ๋Œ€ํ•œ ์ด๋ ฅํ˜•์ƒ์€ ๋Œ€์ฒด๋กœ ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์— ์˜ํ•œ ์ด๋ ฅํ˜•์ƒ๊ณผ ์œ ์‚ฌํ•˜์˜€๊ณ , ์ฃผ๊ธฐ๊ฑฐ๋™์— ์˜ํ•œ ์—๋„ˆ์ง€์†Œ์‚ฐ์€ ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด ๋Œ€๋น„ ํฌ๊ฒŒ ํ–ฅ์ƒ๋˜์—ˆ๋‹ค.

3.2.2 ํŒŒ๊ดด๋ชจ๋“œ

๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ์‹คํ—˜์ฒด #5 S-NJ-O ๋ฐ #6 S-FJ-O๋Š” ์กฐ์  ๋ฐ ECC ์ž์ผ“์˜ ์†์ƒ์ด ๋Œ€์ฒด๋กœ ๊ฐœ๊ตฌ๋ถ€ ์ฃผ๋ณ€์˜ ๋ชจ์„œ๋ฆฌ ๋ฐ ๋ฒฝ๊ธฐ๋‘ฅ์— ์ง‘์ค‘๋˜์—ˆ๋‹ค. ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #5 S-NJ-O๋Š” Fig. 11(c2)์—์„œ ๋ณด๋“ฏ์ด ๋ถ€๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ ๊ฐœ๊ตฌ๋ถ€ ์ƒ๋ถ€์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ์ธ๋ฐฉ(A)์—์„œ ์‹œ์ž‘๋œ ์กฐ์ ๊ท ์—ด์ด ๋ฒฝ๊ธฐ๋‘ฅ WP1์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ๋Œ€๊ฐ์ธ์žฅ๊ท ์—ด๋กœ ๋ฐœ์ „ํ•˜์—ฌ ๊ธ‰๊ฒฉํ•œ ๊ฐ•๋„์ €ํ•˜๋ฅผ ์ดˆ๋ž˜ํ•˜์˜€๋‹ค. ์ •๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ๋Š” Fig. 12(a1)๊ณผ ๊ฐ™์ด ๊ฐœ๊ตฌ๋ถ€ ํ•˜๋ถ€ ๋ชจ์„œ๋ฆฌ B์—์„œ ์‹œ์ž‘๋œ ์‚ฌ์ธ์žฅ ๊ท ์—ด์ด ์šฐ์ธก ๋ฒฝ๊ธฐ๋‘ฅ WP2 ์•„๋ž˜๋กœ ํ™•์‚ฐํ•˜๋ฉฐ ๊ตญ๋ถ€์ ์ธ ๊ฐ•์ฒดํšŒ์ „์„ ์ผ์œผ์ผฐ๋‹ค.

ECC ์ž์ผ“ ๋ณด๊ฐ• ์‹คํ—˜์ฒด #6 S-FJ-O์˜ ๊ฒฝ์šฐ, ๋ถ€๋ฐฉํ–ฅ ์žฌํ•˜์—์„œ ์ธ์žฅ์— ์ €ํ•ญํ•˜๋Š” ๊ฐœ๊ตฌ๋ถ€ ์ขŒ์ธก์˜ ์ž‘์€ ๋ฒฝ๊ธฐ๋‘ฅ WP2๊ฐ€ Fig. 10(c3)๊ณผ ๊ฐ™์ด ์™„์ „ํžˆ ํŒŒ๋‹จ๋˜์—ˆ๋‹ค. ๋˜ํ•œ ๊ฐœ๊ตฌ๋ถ€ ์šฐ์ธก์—์„œ๋Š” ๋ชจ์„œ๋ฆฌ C์—์„œ ์‹œ์ž‘๋œ ECC ์ž์ผ“์˜ ์‚ฌ์ธ์žฅ๊ท ์—ด์ด ๋ฒฝ๊ธฐ๋‘ฅ WP1 ํ•˜๋ถ€๋กœ ํ™•์‚ฐํ•˜๋Š” ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์ด ๋ฐœ์ƒํ•˜์˜€๋‹ค. ์ด๋Ÿฌํ•œ WP1์˜ ์‚ฌ์ธ์žฅ๊ท ์—ด์€ Fig. 11(a2)์—์„œ ๋ณด๋Š” ๋ฐ”์™€ ๊ฐ™์ด ์กฐ์ ๋ฒฝ์ฒด์—๋„ ๋ฐœ์ƒํ•˜์˜€๋‹ค. Fig. 11(b)๋Š” ๊ฐœ๊ตฌ๋ถ€ ์ขŒ์šฐ์— ์„ค์น˜๋œ ๋ฒฝ๊ธฐ๋‘ฅ WP2์™€ WP1์˜ ECC ์ž์ผ“์— ๋ฐœ์ƒํ•œ ๊ท ์—ด ๋ถ„ํฌ๋ฅผ ๋ณด์—ฌ์ฃผ๋Š”๋ฐ, ECC ์ž์ผ“์€ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ๊ท ์—ด ์–‘์ƒ์„ ๋ณด์˜€๋‹ค. ์ฒซ์งธ, ์‚ฌ์ธ์žฅ๊ท ์—ด์€ ๊ฐœ๊ตฌ๋ถ€ ๋ชจ์„œ๋ฆฌ์—์„œ ์‹œ์ž‘๋˜์–ด ECC ํŒจ๋„ ๋‚ด๋ถ€๋กœ ํ™•์‚ฐํ•˜์˜€๋‹ค. ๋‘˜์งธ, ์‚ฌ์ธ์žฅ๊ท ์—ด๊ณผ๋Š” ๋ณ„๋„๋กœ ๋ฒฝ๊ธฐ๋‘ฅ์˜ ์ƒ๋ถ€์™€ ํ•˜๋ถ€์—๋Š” ์ˆ˜ํ‰ ํœจ๊ท ์—ด์ด ๋‹ค์ˆ˜ ๊ด€์ฐฐ๋˜์—ˆ์œผ๋ฉฐ, ์ด๋Š” Fig. 1(b)์— ๋‚˜ํƒ€๋‚ธ ๋ณต๊ณก๋ฅ ๊ฑฐ๋™์„ ์ˆ˜๋ถ„ํ•˜๋Š” ๋ฒฝ๊ธฐ๋‘ฅ์˜ ๊ตญ๋ถ€์ ์ธ ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™๊ณผ ์ผ์น˜ํ•˜๋Š” ๊ท ์—ด์–‘์ƒ์ด๋‹ค.

Fig. 12 Crack patterns of masonry and engineered cementitious composite (ECC) jacket in specimens #5 and #6 with opening
../../Resources/KCI/JKCI.2023.35.4.397/fig12.png

4. ๊ฒฐ๊ณผ ๋น„๊ต

4.1 ECC ์ž์ผ“์— ์˜ํ•œ ๋‚ด์ง„์„ฑ๋Šฅ ํ–ฅ์ƒ ํšจ๊ณผ

๊ฐ ์‹คํ—˜์ฒด์˜ ํฌ๋ฝ๊ณก์„ (envelop curve ๋˜๋Š” backbone curve)์„ Fig. 13์— ๋‚˜ํƒ€๋ƒˆ๊ณ , ์ด๋กœ๋ถ€ํ„ฐ ๊ตฌํ•œ ์ •๋ฐฉํ–ฅ ๋ฐ ๋ถ€๋ฐฉํ–ฅ์˜ ์ตœ๋Œ€ํ•˜์ค‘($P_{u}$), ํŒŒ๊ดด๋ณ€ํ˜•($\delta_{u}$), ์œ ํšจ๊ฐ•์„ฑ($K_{e}$), ํ•ญ๋ณต๋ณ€์œ„๋น„($\delta_{y}$), ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ Table 2์— ์ •๋ฆฌํ•˜์˜€๋‹ค. ๊ฐ ํŠน์„ฑ๊ฐ’์˜ ์ •์˜๋Š” Fig. 14๋ฅผ ์ฐธ๊ณ ํ•œ๋‹ค(Kim et al. 2022). Table 2์—์„œ ์œ ํšจ๊ฐ•์„ฑ($K_{e}$) ๋ฐ ํ•ญ๋ณต๋ณ€์œ„๋น„($\delta_{y}$)์€ ์ด๋ ฅ๊ฑฐ๋™์˜ ์˜ํ–ฅ์œผ๋กœ ์ธํ•˜์—ฌ ์ •๋ฐฉํ–ฅ ํฌ๋ฝ๊ณก์„ (์ตœ์ดˆ ์žฌํ•˜๋ฐฉํ–ฅ)๊ณผ ๋ถ€๋ฐฉํ–ฅ ํฌ๋ฝ๊ณก์„ ์—์„œ ์ธก์ •ํ•œ ๊ฐ’์ด ํฐ ์ฐจ์ด๋ฅผ ๋ณด์˜€๋‹ค. ์ฆ‰, #5 S-NJ-O๋ฅผ ์ œ์™ธํ•œ ๋ชจ๋“  ์‹คํ—˜์ฒด์—์„œ ์ •๋ฐฉํ–ฅ ํฌ๋ฝ๊ณก์„ ์—์„œ ์œ ํšจ๊ฐ•์„ฑ์€ ๋” ์ž‘์•˜๊ณ  ํ•ญ๋ณต๋ณ€์œ„๋น„๋Š” ๋” ์ปธ๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์žฌํ•˜์ˆœ์„œ์™€ ๊ด€๊ณ„๋œ ์ด๋ ฅ๊ฑฐ๋™์˜ ์˜ํ–ฅ์„ ๋ฐฐ์ œํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์ •๋ฐฉํ–ฅ์˜ ์œ ํšจ๊ฐ•์„ฑ ๋ฐ ํ•ญ๋ณต๋ณ€์œ„๋น„๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์‹คํ—˜์ฒด์˜ ๋‚ด์ง„์„ฑ๋Šฅ์„ ๋น„๊ตํ•˜์˜€๋‹ค. ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์‹คํ—˜์ฒด์˜ ๊ฐ•๋„, ๋ณ€ํ˜•๋Šฅ๋ ฅ, ์œ ํšจ๊ฐ•์„ฑ ๋ฐ ์—๋„ˆ์ง€์†Œ์‚ฐ๋Šฅ๋ ฅ์€ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜€๋‹ค.

์ฒซ์งธ, ECC ์ž์ผ“์€ ์กฐ์ ๋ฒฝ์ฒด์˜ ๋ฉด๋‚ด ํšก๊ฐ•๋„๋ฅผ ์ฆ๊ฐ€์‹œ์ผฐ๋‹ค. Fig. 13 ๋ฐ Table 2์—์„œ ๋ณด๊ฐ• ์‹คํ—˜์ฒด #2 C-FJ, #4 S-FJ ๋ฐ #6 S-FJ-O๋Š” ๊ฐ๊ฐ ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #1 C-NJ, #3 S-NJ ๋ฐ #5 S-NJ-O์™€ ๋น„๊ตํ•˜์—ฌ ์ตœ๋Œ€ํ•˜์ค‘($P_{u}$)์ด ์•ฝ 2๋ฐฐ ์ˆ˜์ค€์œผ๋กœ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ด๋Š” ECC ์ž์ผ“์ด ์กฐ์ ๋ฒฝ์ฒด์˜ ์ˆ˜ํ‰์ค„๋ˆˆ์ธ์žฅํŒŒ๊ดด(๊ฐ•์ฒดํšŒ์ „ํŒŒ๊ดด, ๊ฐœ๊ตฌ๋ถ€ ์—†๋Š” ๊ฒฝ์šฐ) ๋ฐ ๊ฐœ๊ตฌ๋ถ€ ๋ชจ์„œ๋ฆฌ์˜ ์‚ฌ์ธ์žฅ๊ท ์—ด(๋Œ€๊ฐ์ธ์žฅํŒŒ๊ดด, ๊ฐœ๊ตฌ๋ถ€ ์žˆ๋Š” ๊ฒฝ์šฐ)์„ ์–ต์ œํ•จ์œผ๋กœ์จ ๊ฐ•๋„ ํ–ฅ์ƒ์— ๊ธฐ์—ฌํ•˜๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค(Fig. 11์˜ ํŒŒ๊ดด๋ชจ๋“œ ์ฐธ์กฐ).

๋‘˜์งธ, ECC ์ž์ผ“์€ ์กฐ์ ๋ฒฝ์ฒด์˜ ๋ณ€ํ˜•๋Šฅ๋ ฅ ํ–ฅ์ƒ์— ๊ธฐ์—ฌํ•˜์˜€๋‹ค. Table 2์—์„œ ๋ณด๊ฐ• ์‹คํ—˜์ฒด #2 C-FJ, #4 S-FJ ๋ฐ #6 S-FJ-O๋Š” ๊ฐ๊ฐ ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #1 C-NJ, #3 S-NJ ๋ฐ #5 S-NJ-O์™€ ๋น„๊ตํ•˜์—ฌ ํŒŒ๊ดด๋ณ€ํ˜•($\delta_{u}$)์ด ๋™๋“ฑ ๋˜๋Š” ์ฆ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ํŠนํžˆ Fig. 13(c)์—์„œ ๋ณด๋“ฏ์ด ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ์‹คํ—˜์ฒด #5์™€ #6์—์„œ ๋ณ€ํ˜•๋Šฅ๋ ฅ ํ–ฅ์ƒ ํšจ๊ณผ๊ฐ€ ๋‘๋“œ๋Ÿฌ์กŒ๋‹ค. ์ด๋Š” ์šฐ์ˆ˜ํ•œ ์ธ์žฅํŠน์„ฑ์„ ๋ณด์œ ํ•œ ECC ์ž์ผ“์ด ๊ฐœ๊ตฌ๋ถ€ ์ฃผ๋ณ€์—์„œ ์‹œ์ž‘ํ•˜๋Š” ์‚ฌ์ธ์žฅ๊ท ์—ด๊ณผ ๊ทธ๋กœ ์ธํ•œ ์ทจ์„ฑํŒŒ๊ดด๋ฅผ ์™„ํ™”์‹œ์ผฐ๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ๋‹ค๋งŒ, Fig. 12(b)์—์„œ ECC ์ž์ผ“์€ ๋ฒฝ๊ธฐ๋‘ฅ WP2์˜ ์ธ์žฅํŒŒ๋‹จ์„ ์™„์ „ํžˆ ๋ฐฉ์ง€ํ•˜์ง€๋Š” ๋ชปํ•˜์˜€๋Š”๋ฐ, ํ–ฅํ›„ ์ด์— ๋Œ€ํ•œ ์ƒ์„ธ ๊ฐœ์„ ์ด ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

์…‹์งธ, ECC ์ž์ผ“์€ ์กฐ์ ๋ฒฝ์ฒด์˜ ๊ฐ•์„ฑ์„ ์ฆ๊ฐ€์‹œ์ผฐ๋‹ค. Fig. 12 ๋ฐ Table 2์—์„œ ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ๋ณด๊ฐ• ์‹คํ—˜์ฒด #2 C-FJ ๋ฐ #4 S-FJ์˜ ์œ ํšจ๊ฐ•์„ฑ($K_{e}$, ์ •๋ฐฉํ–ฅ ์žฌํ•˜)์€ ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #1 C-NJ ๋ฐ #3 S-NJ ๋Œ€๋น„ 1.78๋ฐฐ ๋ฐ 4.68๋ฐฐ ์ˆ˜์ค€์œผ๋กœ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ด๋Š” ์šฐ์ˆ˜ํ•œ ์žฌ๋ฃŒ๊ฐ•์„ฑ(์ฆ‰, ํƒ„์„ฑ๊ณ„์ˆ˜)์„ ๊ฐ–๋Š” ECC ์ž์ผ“์ด ๊ฐ•๊ฑดํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ์•ต์ปค ์ ‘ํ•ฉ๋ถ€์— ์˜ํ•ด ๊ธฐ์กด ์กฐ์ ๋ฒฝ์ฒด์— ์ผ์ฒดํ™”๋˜์–ด ์žฌํ•˜ ์ดˆ๊ธฐ๋ถ€ํ„ฐ ํšกํ•˜์ค‘์„ ๋ถ„๋‹ดํ•˜์˜€์Œ์„ ๋ณด์—ฌ์ค€๋‹ค. ์ฐธ๊ณ ๋กœ, Table 2์—์„œ ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ๊ฒฝ์šฐ ECC ์ž์ผ“ ๋ณด๊ฐ• ์‹คํ—˜์ฒด #6 S-FJ-O์˜ ์œ ํšจ๊ฐ•์„ฑ์ด ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #5 S-NJ-O์˜ ์œ ํšจ๊ฐ•์„ฑ๋ณด๋‹ค ์ž‘๋‹ค. ์ด๋Š” ์œ ํšจ๊ฐ•์„ฑ ์‚ฐ์ • ์‹œ ๊ธฐ์ค€์œผ๋กœ ์‚ผ์€ ์ตœ๋Œ€ํ•˜์ค‘์˜ 60 %์— ๋„๋‹ฌํ•˜๊ธฐ ์ด์ „์— #6 S-FJ-O ์‹คํ—˜์ฒด์— ๊ท ์—ด๋กœ ์ธํ•œ ๊ฐ•์„ฑ ์ €ํ•˜๊ฐ€ ํฌ๊ฒŒ ๋ฐœ์ƒํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์ด๋ฉฐ, Fig. 12(c)๋ฅผ ์ฐธ๊ณ ํ•  ๊ฒฝ์šฐ 0.6$P_{u}$์— ๋„๋‹ฌํ•˜๊ธฐ ์ด์ „์˜ ์ดˆ๊ธฐ๊ฐ•์„ฑ์€ ECC ๋ณด๊ฐ• #6 S-FJ-O์ด ๋น„๋ณด๊ฐ• #5 S-NJ-O๋ณด๋‹ค ๋” ์ปธ๋‹ค.

๋„ท์งธ, ECC ์ž์ผ“์€ ์กฐ์ ๋ฒฝ์ฒด์˜ ์—๋„ˆ์ง€์†Œ์‚ฐ๋Šฅ๋ ฅ์„ ์ฆ๊ฐ€์‹œ์ผฐ๋‹ค. Fig. 15๋Š” ์‹คํ—˜์ฒด๋ณ„ ํšก๋ณ€์œ„๋น„์— ๋”ฐ๋ฅธ ์ฃผ๊ธฐ๋‹น ์—๋„ˆ์ง€์†Œ์‚ฐ๋Ÿ‰($E_{D}$) ๋ฐ ์—๋„ˆ์ง€์†Œ์‚ฐ๋น„($\kappa$, energy dissipation ratio) ๋ณ€ํ™”๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ์—๋„ˆ์ง€์†Œ์‚ฐ๋Ÿ‰ $E_{D}$๋Š” ์ด๋ ฅ๋ชจ๋ธ๋ง์— ํ™œ์šฉ๋  ์ˆ˜ ์žˆ๋„๋ก ๊ฐ ๋ณ€์œ„๋‹จ๊ณ„๋งˆ๋‹ค ์ฃผ๊ธฐ์ด๋ ฅ๊ณก์„ ์˜ ๋ฉด์ ์œผ๋กœ ๊ณ„์‚ฐํ•˜์˜€๊ณ , ์—๋„ˆ์ง€์†Œ์‚ฐ๋น„ $\kappa$์˜ ์ •์˜๋Š” Fig. 15(b)๋ฅผ ์ฐธ๊ณ ํ•œ๋‹ค. Fig. 15(a)์—์„œ ECC ์ž์ผ“ ๋ณด๊ฐ• ์‹คํ—˜์ฒด์˜ ์ฃผ๊ธฐ๋‹น ์—๋„ˆ์ง€์†Œ์‚ฐ๋Ÿ‰์€ ๋Œ€์ฒด๋กœ ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด๋ณด๋‹ค ๋” ์ปธ๋‹ค. ํ•˜์ง€๋งŒ Fig. 15(b)์— ๋‚˜ํƒ€๋‚ธ ์—๋„ˆ์ง€์†Œ์‚ฐ๋น„์˜ ๊ฒฝ์šฐ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์‹คํ—˜์ฒด์—์„œ ์œ ์‚ฌํ•œ ๊ฐ’๋“ค์„ ๋ณด์˜€๋Š”๋ฐ, ์ด๋Š” ECC๋ณด๊ฐ• ์‹คํ—˜์ฒด์˜ ์—๋„ˆ์ง€์†Œ์‚ฐ๋Ÿ‰ ์ฆ๊ฐ€๊ฐ€ ์ฆ๊ฐ€๋œ ๊ฐ•๋„์— ๋น„๋ก€ํ•˜์—ฌ ์ฆ๊ฐ€ํ•˜์˜€์Œ์„ ๋ณด์—ฌ์ค€๋‹ค. ์—๋„ˆ์ง€์†Œ์‚ฐ๋น„๋Š” ํ•ญ๋ณต์ดˆ๊ธฐ์ธ ํšก๋ณ€์œ„๋น„ 0.2 % ๋‚ด์™ธ์—์„œ ์•ฝ $\kappa$=0.6์˜ ๊ฐ’์„ ๋ณด์˜€์œผ๋ฉฐ, ์ดํ›„ ๊ธ‰๊ฒฉํžˆ ๊ฐ์†Œํ•˜์—ฌ ํšก๋ณ€์œ„๋น„ 0.5 % ์ดํ›„๋กœ๋Š” $\kappa$=0.2์˜ ์ผ์ •ํ•œ ๊ฐ’์„ ๋ณด์˜€๋‹ค.

Fig. 13 Envelope curves
../../Resources/KCI/JKCI.2023.35.4.397/fig13.png
Fig. 14 Definition of symbols
../../Resources/KCI/JKCI.2023.35.4.397/fig14.png
Fig. 15 Hysteretic energy dissipation per load cycle
../../Resources/KCI/JKCI.2023.35.4.397/fig15.png
Table 2 Summary of test results

Specimen

Positive loading

Negative loading

Failure mode1)

$P_{u}$ (kN)

$\delta_{u}$ (%)

$K_{e}$ (kN/m)

$\delta_{y}$ (%)

$P_{u}$ (kN)

$\delta_{u}$ (%)

$K_{e}$ (kN/m)

$\delta_{y}$ (%)

#1 C-NJ

74.3

2.40

18.3

0.16

63.2

1.70

58.4

0.05

R & TC

#2 C-FJ

154.3

2.50

32.6

0.16

153.4

2.00

67.7

0.08

R, TC, and TR

#3 S-NJ

77.0

1.50

16.6

0.20

63.7

1.30

58.1

0.06

R & TC

#4 S-FJ

161.9

2.00

77.7

0.08

164.7

1.40

140.6

0.04

R, TC, and AF

#5 S-NJ-O

74.5

0.63

49.7

0.07

54.5

0.63

19.5

0.12

DT & TC of WP1

#6 S-FJ-O

158.2

1.25

23.4

0.23

126.3

0.60

65.4

0.08

TR of WP2

Notes: 1)R: rocking of masonry; TC: toe crushing of masonry; TR: tensile rupture of ECC jacket; AF: concrete anchor failure; DT: diagonal tension failure of masonry; WP1 and WP2 are the wall piers on either side of the opening

4.2 ์กฐ์ ์ƒํƒœ ๋ฐ ๊ตฌ์กฐ์ƒ์„ธ์˜ ์˜ํ–ฅ

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐœ๊ตฌ๋ถ€, ๊ณต๊ฐ„์Œ“๊ธฐ, ์ค„๋ˆˆ์‚ฌ์ถค ๋ถˆ๋Ÿ‰, ECC ์ž์ผ“ ํŽธ์‹ฌ ๋ณด๊ฐ•(์™ธ๋ถ€๋ณด๊ฐ•) ๋“ฑ ๊ตญ๋‚ด ๋…ธํ›„์ฃผํƒ์˜ ์กฐ์ ํŠน์„ฑ ๋ฐ ๋ณด๊ฐ•์ƒ์„ธ๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๋‚ด์ง„์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์‹คํ—˜๊ฒฐ๊ณผ๋กœ๋ถ€ํ„ฐ ์ด๋Ÿฌํ•œ ์š”์ธ์ด ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์˜ ์ง€์ง„๊ฑฐ๋™์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์€ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์œ ์ถ”ํ•  ์ˆ˜ ์žˆ๋‹ค.

์ฒซ์งธ, ๊ฐœ๊ตฌ๋ถ€๋Š” ์กฐ์ ๋ฒฝ์ฒด์˜ ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๋ณ€ํ™”์‹œ์ผœ ๊ฐ•๋„, ์—ฐ์„ฑ ๋“ฑ ๋‚ด์ง„์„ฑ๋Šฅ์„ ์ €ํ•˜์‹œ์ผฐ๋‹ค. ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์‹คํ—˜์ฒด #1-#4์—์„œ๋Š” ์—ฐ์„ฑ๋ชจ๋“œ์ธ ๊ฐ•์ฒดํšŒ์ „์— ์˜ํ•ด ์ง€๋ฐฐ๋˜์—ˆ๊ณ , ๊ทธ ๊ฒฐ๊ณผ ํšก๋ณ€์œ„๋น„ 2 % ์ˆ˜์ค€์˜ ๋ณ€ํ˜•๋Šฅ๋ ฅ์ด ํ™•๋ณด๋œ ์•ˆ์ •์ ์ธ ๋‚ด์ง„์„ฑ๋Šฅ์„ ๋ณด์˜€๋‹ค. ๋ฐ˜๋ฉด, ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ์‹คํ—˜์ฒด #5 ๋ฐ #6์—์„œ๋Š” ๋Œ€๊ฐ์ธ์žฅํŒŒ๊ดด, ๋ฒฝ๊ธฐ๋‘ฅ ์ธ์žฅํŒŒ๋‹จ ๋“ฑ ์ทจ์„ฑํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๊ณ  ๊ทธ๋กœ ์ธํ•ด ๊ฐ•๋„ ๋ฐ ๋ณ€ํ˜•๋Šฅ๋ ฅ์ด ๊ฐ์†Œํ•˜์˜€๋‹ค.

๋‘˜์งธ, ๊ณต๊ฐ„์Œ“๊ธฐ ์—ฌ๋ถ€๋Š” ๊ฐ•์ฒดํšŒ์ „์ด ์ง€๋ฐฐ์ ์ธ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์˜ ๋‚ด์ง„์„ฑ๋Šฅ์— ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜์ง€ ์•Š์•˜๋‹ค. ๋น„๋ณด๊ฐ• ๊ณต๊ฐ„์Œ“๊ธฐ๋ฒฝ ์‹คํ—˜์ฒด #1 C-NJ์˜ ๊ฐ•๋„, ๊ฐ•์„ฑ ๋ฐ ์—ฐ์„ฑ์€ ๋น„๋ณด๊ฐ• ์ผ๋ฐ˜์Œ“๊ธฐ๋ฒฝ ์‹คํ—˜์ฒด #3 S-NJ์™€ ๊ฑฐ์˜ ๋™๋“ฑํ•˜์˜€๊ณ , ECC ์ž์ผ“ ๋ณด๊ฐ• ๊ณต๊ฐ„์Œ“๊ธฐ๋ฒฝ ์‹คํ—˜์ฒด #2 C-FJ์˜ ๊ฐ•๋„, ๊ฐ•์„ฑ ๋ฐ ์—ฐ์„ฑ ๋˜ํ•œ ECC ์ž์ผ“ ๋ณด๊ฐ• ์ผ๋ฐ˜์Œ“๊ธฐ๋ฒฝ ์‹คํ—˜์ฒด #4 S-FJ์™€ ๊ฑฐ์˜ ๋™๋“ฑํ•˜์˜€๋‹ค(Fig. 11 ๋ฐ Fig. 13 ์ฐธ์กฐ). ์ด๋Š”, ๊ณต๊ฐ„ ๋‚ด์ธก ๋ฐ ์™ธ์ธก ์กฐ์ ์ด ์ฝ˜ํฌ๋ฆฌํŠธ ํ…Œ๋‘๋ฆฌ๋ณด ๋˜๋Š” ์Šฌ๋ž˜๋ธŒ์— ์˜ํ•ด ๊ตฌ์†๋˜์–ด ์ผ์ฒด๋กœ ๊ฑฐ๋™ํ•  ๊ฒฝ์šฐ์—๋Š” ์กฐ์ ๋ฒฝ ๋‚ด๋ถ€ ์œ ๊ฒฉ์ด ๊ตฌ์กฐ์„ฑ๋Šฅ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์ด ์ œํ•œ์ ์ž„์„ ์˜๋ฏธํ•œ๋‹ค.

์…‹์งธ, ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์„ ๋ณด์ธ ์‹คํ—˜์ฒด #1~#4์—์„œ๋Š” ์ค„๋ˆˆ์‚ฌ์ถค ๋ถˆ๋Ÿ‰์˜ ์˜ํ–ฅ์ด ์ œํ•œ์ ์ด์—ˆ๋˜ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์€ ๊ธฐ๋ณธ์ ์œผ๋กœ ์ˆ˜ํ‰์ค„๋ˆˆ์˜ ์ธ์žฅํŒŒ๋‹จ์„ ์ˆ˜๋ฐ˜ํ•˜๋Š”๋ฐ, ์‹คํ—˜์ฒด์—์„œ๋Š” ์ˆ˜์ง์ค„๋ˆˆ์ด ๋ถˆ์ถฉ๋ถ„ํ•˜๊ฒŒ ์‚ฌ์ถค๋˜์—ˆ์Œ์—๋„ ๋ถˆ๊ตฌํ•˜๊ณ  ์ˆ˜ํ‰์ค„๋ˆˆ์„ ๋”ฐ๋ผ ์ค„๋ˆˆ์ธ์žฅํŒŒ๋‹จ์ด ๋ฐœ์ƒ๋˜์—ˆ๋‹ค. ๋‹ค๋งŒ, ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด #5 S-NJ-O๋Š” ๋ฒฝ๊ธฐ๋‘ฅ์˜ ๋Œ€๊ฐ์ธ์žฅ๊ท ์—ดํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋Š”๋ฐ, ์ด ๊ฒฝ์šฐ ๋Œ€๊ฐ๊ท ์—ด์ด ๋ถ€๋ถ„์ ์œผ๋กœ ์ˆ˜์ง์ค„๋ˆˆ์„ ๋”ฐ๋ผ ๋ฐœ์ƒํ•˜๋ฏ€๋กœ ์ค„๋ˆˆ์‚ฌ์ถค ๋ถˆ๋Ÿ‰์ด ๊ฐ•๋„, ์—ฐ์„ฑ ๋“ฑ ๋‚ด์ง„์„ฑ๋Šฅ์„ ์ €ํ•˜์‹œ์ผฐ์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ๋ณด๊ฐ• ์‹คํ—˜์ฒด #6 S-FJ-O์—์„œ๋Š” ECC ์ž์ผ“์ด ์กฐ์ ๊ท ์—ด์„ ์–ต์ œํ•˜๋ฏ€๋กœ ์ค„๋ˆˆ์‚ฌ์ถค ๋ถˆ๋Ÿ‰์˜ ์˜ํ–ฅ์ด ์ œํ•œ์ ์ด์—ˆ์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

๋„ท์งธ, ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์‹คํ—˜์ฒด๋Š” ์กฐ์ ๋ฒฝ์ฒด๊ฐ€ ํ•œ์ชฝ์— ์น˜์šฐ์ณ์žˆ๊ณ  ECC ์ž์ผ“ ๋˜ํ•œ ๋ฐ”๊นฅ๋ฉด์—์„œ๋งŒ ์„ค์น˜๋˜์–ด ์‹คํ—˜ ์ค‘ ํŽธ์‹ฌํ•˜์ค‘์ด ์ž‘์šฉ๋˜์—ˆ๋‹ค. ํ•˜์ง€๋งŒ ํŽธ์‹ฌ๋ฐฉ์ง€์šฉ ํšก์ง€์ง€๋ฅผ ์„ค์น˜ํ•˜์—ฌ ์‹คํ—˜ํ•œ ๊ฒฐ๊ณผ ํŽธ์‹ฌ ๋ฐ ๊ทธ๋กœ ์ธํ•œ ๋ฉด์™ธ๋ฐฉํ–ฅ ์•ˆ์ •์„ฑ ๋ฌธ์ œ๊ฐ€ ํฌ๊ฒŒ ํ™•์ธ๋˜์ง€๋Š” ์•Š์•˜๋‹ค. ์ด๋Š” ์กฐ์ ๋ฒฝ์ฒด์˜ ํ•œ์ชฝ ๋ฉด์—๋งŒ ECC ์ž์ผ“์„ ์„ค์น˜ํ•˜๋”๋ผ๋„ ์ „์ฒด ๊ฑด๋ฌผ ์ˆ˜์ค€์—์„œ ๋ฉด์™ธ ์•ˆ์ •์„ฑ์ด ํ™•๋ณด๋˜์—ˆ๋‹ค๋ฉด ์˜๋„ํ•œ ๋ณด๊ฐ• ํšจ๊ณผ๋ฅผ ์–ป์„ ์ˆ˜ ์žˆ์Œ์„ ๋ณด์—ฌ์ค€๋‹ค. ๋‹ค๋งŒ, ์กฐ์ ๋ฒฝ์ฒด ํ•˜๋ถ€ ๋ฐ ECC ์ž์ผ“ ์•ต์ปค์ ‘ํ•ฉ๋ถ€์—์„œ๋Š” ํŽธ์‹ฌํ•˜์ค‘์˜ ์˜ํ–ฅ์œผ๋กœ ๋ณด์ด๋Š” ์กฐ์ ์••๊ดด ๋ฐ ์ฝ˜ํฌ๋ฆฌํŠธ ํŒŒ์—ด์ด ๊ด€์ฐฐ๋˜์—ˆ๋‹ค(Fig. 11 ์ฐธ์กฐ). ๋”ฐ๋ผ์„œ ํ•˜์ค‘์ „๋‹ฌ ๊ฒฝ๋กœ์ƒ์— ์žˆ๋Š” ์•ต์ปค์ ‘ํ•ฉ๋ถ€์—์„œ๋Š” ํŽธ์‹ฌ์˜ ์˜ํ–ฅ์ด ๊ณผ๋„ํ•˜์ง€ ์•Š๋„๋ก ๊ตฌ์กฐ์ƒ์„ธ์— ์ฃผ์˜ํ•ด์•ผ ํ•œ๋‹ค.

5. ๊ฒฐ ๋ก 

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๊ตญ๋‚ด ๋…ธํ›„ ๊ฑด๋ฌผ์˜ ์กฐ์ ์ƒํƒœ๋ฅผ ๋ฐ˜์˜ํ•œ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์˜ ๋‚ด์ง„์„ฑ๋Šฅ์„ ์‹คํ—˜์ ์œผ๋กœ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๋…ธํ›„ ๊ฑด๋ฌผ์˜ ์กฐ์ ์ƒํƒœ๋กœ๋Š” ๊ณต๊ฐ„์Œ“๊ธฐ, ์ค„๋ˆˆ์‚ฌ์ถค ๋ถˆ๋Ÿ‰, ๊ฐœ๊ตฌ๋ถ€ ๋“ฑ ๋‚ด์ง„์„ฑ๋Šฅ์— ๋ถˆ๋ฆฌํ•œ ์š”์ธ๋“ค์ด ๊ณ ๋ ค๋˜์—ˆ๊ณ , ์ด์— ๋Œ€ํ•œ ๋ณด๊ฐ•๋ฐฉ๋ฒ•์œผ๋กœ๋Š” ECC ์ž์ผ“(๋‘๊ป˜ 40 mm)์„ ๋ฐ”๊นฅ ์กฐ์ ํ‘œ๋ฉด์— ์„ค์น˜ํ•œ ํŽธ์‹ฌ ์™ธ๋ถ€๋ณด๊ฐ•๋ฐฉ๋ฒ•์„ ์ ์šฉํ•˜์˜€๋‹ค. ์ฃผ์š” ๊ฒฐ๊ณผ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

1) ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ๊ฒฝ์šฐ, ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด๋Š” ๋ชจ๋‘ ๊ฐ•์ฒดํšŒ์ „์— ์˜ํ•œ ํŒŒ๊ดด๋ชจ๋“œ ๋ฐ ๊ฑฐ๋™ํŠน์„ฑ์„ ๋ณด์˜€๋‹ค. ์กฐ์  ๋ฐ ECC ์ž์ผ“์˜ ์†์ƒ์€ ๋ฒฝ์ฒด ํ•˜๋ถ€์— ์ง‘์ค‘๋˜์—ˆ๊ณ , ์ธ์žฅ์ธก์—์„œ๋Š” ์กฐ์  ๋ฐ ECC ์ž์ผ“์˜ ์ˆ˜ํ‰๊ท ์—ด์ด ๋ฐœ์ƒํ•˜์˜€๊ณ  ์••์ถ•์ธก์—์„œ ์กฐ์ ๋‹จ๋ถ€์••๊ดด ๋ฐ ํ•˜๋ถ€ ๋ณด์˜ ์ฝ˜ํฌ๋ฆฌํŠธํŒŒ์—ด์ด ๋ฐœ์ƒํ•˜์˜€๋‹ค. ๊ณ„์ธก๋œ ํฌ๋ฝ๊ณก์„  ๋ฐ ์ฃผ๊ธฐ๊ณก์„ ์€ ์ „ํ˜•์ ์ธ ๊ฐ•์ฒดํšŒ์ „ ๊ฑฐ๋™๊ณผ ๊ฑฐ์˜ ๊ฐ™์•˜๋‹ค.

2) ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ๊ฒฝ์šฐ, ๋น„๋ณด๊ฐ• ์‹คํ—˜์ฒด๋Š” ๊ฐœ๊ตฌ๋ถ€ ์ƒ๋ถ€ ์ธ๋ฐฉ ๋‹จ๋ถ€์—์„œ ์‹œ์ž‘๋œ ๊ท ์—ด์— ์˜ํ•œ ๋Œ€๊ฐ์ธ์žฅํŒŒ๊ดด(์ทจ์„ฑํŒŒ๊ดด)๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๊ณ , ECC ์ž์ผ“์ด ๋Œ€๊ฐ๊ท ์—ด์„ ์–ต์ œํ•œ ๋ณด๊ฐ• ์‹คํ—˜์ฒด๋Š” ๊ฐœ๊ตฌ๋ถ€ ์ฃผ๋ณ€ ๋ฒฝ๊ธฐ๋‘ฅ์˜ ์ธ์žฅํŒŒ๋‹จ์— ์˜ํ•ด ํŒŒ๊ดด๋˜์—ˆ๋‹ค. ์ด๋“ค ์‹คํ—˜์ฒด์˜ ์ „๋ฐ˜์ ์ธ ํ•˜์ค‘-๋ณ€ํ˜• ๊ด€๊ณ„๋Š” ๊ฐ•์ฒดํšŒ์ „์— ์˜ํ•œ ๊ฑฐ๋™๊ณผ ์œ ์‚ฌํ•˜์˜€๋‹ค.

3) ECC ์ž์ผ“์€ ์กฐ์ ๋ฒฝ์ฒด์˜ ๊ฐ•๋„, ๊ฐ•์„ฑ, ๋ณ€ํ˜•๋Šฅ๋ ฅ ๋ฐ ์—๋„ˆ์ง€์†Œ์‚ฐ๋Šฅ๋ ฅ์„ ํ–ฅ์ƒ์‹œ์ผฐ๋‹ค. ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์‹คํ—˜์ฒด์—์„œ ECC ์ž์ผ“์€ ๋ฒฝ์ฒด ํ•˜๋ถ€ ์ˆ˜ํ‰์ค„๋ˆˆ์„ ๋”ฐ๋ผ ๋ฐœ์ƒํ•˜๋Š” ๊ท ์—ด๊ฐ•๋„๋ฅผ ์ฆ์ง„์‹œ์ผœ ๊ฐ•์ฒดํšŒ์ „์— ์˜ํ•œ ๊ฐ•๋„ ๋ฐ ๊ฐ•์„ฑ(์ดˆ๊ธฐ๊ฐ•์„ฑ)์„ ์ฆ๊ฐ€์‹œ์ผฐ๊ณ , ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ์‹คํ—˜์ฒด์—์„œ๋Š” ๋ชจ์„œ๋ฆฌ ์ฃผ๋ณ€ ์‚ฌ์ธ์žฅ๊ท ์—ด์„ ์–ต์ œํ•˜์—ฌ ๊ฐ•๋„ ๋ฐ ์—ฐ์„ฑ์„ ์ฆ๊ฐ€์‹œ์ผฐ๋‹ค. ๋ณด๊ฐ• ์‹คํ—˜์ฒด์˜ ์—๋„ˆ์ง€์†Œ์‚ฐ๋Ÿ‰์€ ์ฆ๊ฐ€๋œ ๊ฐ•๋„์— ๋น„๋ก€ํ•˜์—ฌ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค.

4) ๊ฐœ๊ตฌ๋ถ€๋Š” ์กฐ์ ๋ฒฝ์ฒด์˜ ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๋ณ€๊ฒฝ์‹œ์ผœ ๋‚ด์ง„์„ฑ๋Šฅ์— ํฐ ์˜ํ–ฅ์„ ๋ฏธ์ณค๋‹ค. ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์—†๋Š” ์กฐ์ ๋ฒฝ์ฒด๋Š” ์—ฐ์„ฑ์ ์ธ ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์„ ๋ณด์˜€์ง€๋งŒ, ๊ฐœ๊ตฌ๋ถ€๊ฐ€ ์žˆ๋Š” ๊ฒฝ์šฐ ์กฐ์  ๋Œ€๊ฐ์ธ์žฅํŒŒ๊ดด์— ์˜ํ•œ ์ทจ์„ฑ๊ฑฐ๋™์„ ๋ณด์˜€๋‹ค. ๋ฐ˜๋ฉด ๊ณต๊ฐ„์Œ“๊ธฐ, ์ค„๋ˆˆ์‚ฌ์ถค ๋ถˆ๋Ÿ‰๊ณผ ๊ฐ™์€ ๋…ธํ›„ ์ฃผํƒ์˜ ์กฐ์ ์ƒํƒœ๋Š” ๋น„๋ก ๊ฐ•์ฒดํšŒ์ „๊ฑฐ๋™์„ ๋ณด์ธ ์‹คํ—˜์ฒด์— ํ•œ์ •๋˜๊ธฐ๋Š” ํ•˜์ง€๋งŒ ๋‚ด์ง„์„ฑ๋Šฅ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์ด ์ œํ•œ์ ์ด์—ˆ๋‹ค. ์ „์ฒด ์‹คํ—˜์ฒด๊ฐ€ ๋ฉด์™ธ๋ฐฉํ–ฅ์œผ๋กœ ํšก์ง€์ง€๋œ ์‹คํ—˜์ฒด์—์„œ ECC ์ž์ผ“์˜ ํŽธ์‹ฌ ๋ณด๊ฐ•์ด ๋‚ด์ง„์„ฑ๋Šฅ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์€ ์ œํ•œ์ ์ด์—ˆ์ง€๋งŒ, ๊ตญ๋ถ€์ ์œผ๋กœ๋Š” ํ›„์„ค์น˜ ์•ต์ปค์ ‘ํ•ฉ๋ถ€์—์„œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ธŒ๋ ˆ์ดํฌ์•„์›ƒ ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค.

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๋…ธํ›„ ๊ฑด๋ฌผ์˜ ์กฐ์ ์ƒํƒœ๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๋น„๋ณด๊ฐ• ๋ฐ ๋ณด๊ฐ• ์กฐ์ ๋ฒฝ์ฒด์— ๋Œ€ํ•œ ๋‚ด์ง„์‹คํ—˜์„ ํ†ตํ•ด ๊ฑฐ๋™ํŠน์„ฑ ๋ฐ ECC ์ž์ผ“์˜ ๋ณด๊ฐ• ํšจ๊ณผ๋ฅผ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๋‚ด์ง„์„ฑ๋Šฅํ‰๊ฐ€ ๋ฐ ๋ณด๊ฐ•์„ค๊ณ„์— ํ™œ์šฉํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ด๋“ค ์‹คํ—˜์ฒด์˜ ๊ฐ•๋„ ๋ฐ ๊ฐ•์„ฑ์„ ์ •๋Ÿ‰์ ์œผ๋กœ ํ‰๊ฐ€ํ•˜๋Š” ๋ฐฉ๋ฒ•์— ๊ด€ํ•œ ํ›„์† ์—ฐ๊ตฌ๊ฐ€ ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

์ด ์—ฐ๊ตฌ๋Š” ๊ตญํ† ๊ตํ†ต๋ถ€์˜ ์—ฐ๊ตฌ๋น„์ง€์›(RS-2022-00143563)์— ์˜ํ•ด ์ˆ˜ํ–‰๋˜์—ˆ์Œ.

References

1 
Abrams, D. P., and Shah, N. (1992) Cyclic Loading Tests of Unreinforced Masonry Walls. Advanced Construction Technology Center Rep. No. 92-26-10, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL.URL
2 
ASCE (2013) Seismic Evaluation and Retrofit of Existing Buildings (ASCE/SEI 41-13). Reston, VA: American Society of Civil Engineers (ASCE).URL
3 
ASCE (2017) Seismic Evaluation and Retrofit of Existing Buildings (ASCE/SEI 41-17). Reston, VA: American Society of Civil Engineers (ASCE).URL
4 
ASTM C 1314-12 (2012) Standard Test Method for Compressive Strength of Masonry Prisms. West Conshohocken, PA: ASTM International.URL
5 
BSI (2002) BS EN 1052-3 Methods of Test for Masonry-Part 3: Determination of Initial Shear Strength. London, UK: British Standards Institute (BSI).URL
6 
Costley, A. C., and Abrams, D. P. (1996) Dynamic Resoponse of Unreinforced Masonry Buildings with Flexible Diaphragms (NCEER-96-0001). Buffalo, New York: National Center for Earthquake Engineering Reseach (NCEER).URL
7 
Eom, T. S., Kim, J., Kim, S. W., Kim, J. H., Han, J. Y., and Choi, H. (2023) Rocking Behavior of Unreinforced Masonry Walls Under Cyclic Load. EESK Journal of Earthquake Engineering 27(1), 2023. (In Korean)DOI
8 
Esposito, R., and Ravenshorst, G. (2017) Quasi-Static Cyclic In- Plane Tests on Masonry Components. Delft University of Technology.URL
9 
JSCE (1999) Test Method for Tensile Properties of Continuous Fiber Reinforcing Materials (JSCE-E-531). Tokyo, Japan: Japan Society of Civil Engineers (JSCE).URL
10 
Kang, S. H., Hong, S. G., and Lee, S. J. (2010) Rocking Capacity of Unreinforced Masonry Walls. Journal of Architectural Institute of Korea-Structural 26(12), 45-56. (In Korean)URL
11 
Kanno, R., and Choi, H. (2021) A Study on Seismic Performance Evaluation of Masonry Walls: Part 1. In-plane Static Cyclic Loading Test with the Presence or Absence of an Opening. Proceedings of AIJ 2021 Conference. Architectural Institute of Japan (AIJ). 781-782. (In Japanese)URL
12 
KATS (2017) Standard Test Method for Compressive Strength of Concrete (KS F 2405). Seoul, Korea: Korea Agency for Technology and Standards (KATS), Korea Standard Association (KSA). (In Korean)URL
13 
KATS (2018) Concrete Bricks (KS F 4004). Seoul, Korea: Korea Standard Association (KSA), Korea Agency for Technology and Standards (KATS). (In Korean)URL
14 
Kim, C. H., Lee, S. J., Heo, S. J., and Eom, T. S. (2022) Investigation of Seismic Performance of RC Wall-Slab Frames with Masonry Infill. EESK Journal of Earthquake Engineering 26(3), 137-147. (In Korean)DOI
15 
KISC (2013) Guidelines for Seismic Performance Evaluation for Existing Buildings. Korea Infrastructure Safety Corporation (KISC). (In Korean)URL
16 
Lee, S. J., Eom, T. S., and Yu, E. J. (2021) Investigation of Diagonal Strut Actions in Masonry-Infilled Reinforced Concrete Frames. International Journal of Concrete Structures and Materials 15(1), 6.DOI
17 
Mahmoudimotlagh, S. (2020) Numerical Modeling of the In-Plane Seismic Behavior of Unreinforced Masonry Wall Retrofitted with Bed Joint Reinforcements. MS Thesis. Delft University of Technology.URL
18 
Moon, F. L., Yi, T., Leon, R. T., and Kahn, L. F. (2007) Testing of a Full-Scale Unreinforced Masonry Building Following Seismic Strengthening. Journal of Structural Engineering 133(9), 1215-1226.DOI
19 
Moon, K. L. (2004) Seismic Strenthening of Low-Rise Unreinforced Masonry Structures with Flexible Diaphragms. Ph.D. Dissertation. Georgia Institute of Technology, Atlanta.URL
20 
Shabani, A., and Kioumarsi, M. (2022) A Novel Macroelement for Seismic Analysis of Unreinforced Masonry Buildings Based on MVLEM in OpenSees. Journal of Building Engineering 49, 104019.DOI
21 
Yi, W. H., Lee, J. H., Oh, S. H., Yang, W. J., and Kang, D. E. (2005) A Study of Evaluation of Shear Capacity of Unreinforced Masonry Wall. Journal of Architectural Institute of Korea-Structural 21(10), 3-10. (In Korean)URL