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  1. ๊ฒฝ๋ถ๋Œ€ํ•™๊ต ๊ฑด์ถ•ํ† ๋ชฉ๊ณตํ•™๋ถ€ ๋ฐ•์‚ฌํ›„์—ฐ๊ตฌ์› (Kyungpook National University)
  2. ๊ฒฝ๋ถ๋Œ€ํ•™๊ต ๊ฑด์ถ•ํ† ๋ชฉ๊ณตํ•™๋ถ€ ๊ต์ˆ˜ (Kyungpook National University)


์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ, ์ฝ”๋ฒจ, ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ, ์ŠคํŠธ๋Ÿฟ, ์œ ํšจ๊ฐ•๋„
Reinforced concrete, Corbel, Strut-tie model, Concrete strut, Effective strength

  • 1. ์„œ ๋ก 

  • 2. ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ

  • 3. ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹

  •   3.1 ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์˜ ์œ ํšจ๊ฐ•๋„ ์‹

  •   3.2 ํ˜„ ์—ฐ๊ตฌ์˜ ์œ ํšจ๊ฐ•๋„ ์‹

  • 4. ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ํ•ด์„

  •   4.1 ์•„์น˜ ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ํ•ด์„

  •   4.2 ๋ณตํ•ฉ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ํ•ด์„

  • 5. ์š”์•ฝ ๋ฐ ๊ฒฐ๋ก 

1. ์„œ ๋ก 

์ตœ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๊ธฐ์ค€(2012)์„ ๋น„๋กฏํ•œ ์„ธ๊ณ„ ์ฃผ์š”์„ค๊ณ„๊ธฐ์ค€์„œ๋Š” ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ๊ณผ ๊ฐ™์ด ๋ณด ๋‹จ๋ถ€์˜ ์ˆ˜์ง๋ ฅ๊ณผ ๋ณด์˜ ๊ฑด์กฐ์ˆ˜์ถ•, ํฌ๋ฆฌํ”„, ์˜จ๋„๋ณ€ํ™” ๋“ฑ์— ๋”ฐ๋ฅธ ์ˆ˜ํ‰๋ ฅ ๋“ฑ์˜ ์ง‘์ค‘ํ•˜์ค‘์„ ๋ฐ›์œผ๋ฉฐ ๊ธฐํ•˜ํ•™์  ํ˜•์ƒ์˜ ๊ธ‰๋ณ€์œผ๋กœ ์‘๋ ฅ์ด ์‹ฌํ•˜๊ฒŒ ๊ต๋ž€๋˜๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ถ€์žฌ์˜ ์„ค๊ณ„๋ฅผ ์œ„ํ•˜์—ฌ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๋ฐฉ๋ฒ•์„ ์ฑ„ํƒํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๋ฐฉ๋ฒ•์€ ์„ค๊ณ„์ž๋กœ ํ•˜์—ฌ๊ธˆ ์‘๋ ฅ๊ต๋ž€์˜์—ญ์„ ๊ฐ–๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ถ€์žฌ ๋‚ด๋ถ€์˜ ํž˜์˜ ์ „๋‹ฌ๊ฒฝ๋กœ์— ๋Œ€ํ•œ ์ดํ•ด๋ฅผ ๋†’์—ฌ ์ต์ˆ™ํ•˜์ง€ ์•Š์€ ์„ค๊ณ„์กฐ๊ฑด์„ ๋‹ค๋ฃจ๋Š” ๋Šฅ๋ ฅ์„ ํ–ฅ์ƒ์‹œํ‚ค๋ฉฐ, ๋˜ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ถ€์žฌ์˜ ์‹ค์ œ์˜ ํŒŒ๊ดด๊ฑฐ๋™์— ๊ธฐ์ดˆํ•œ ์„ค๊ณ„๋ฅผ ๊ฐ€๋Šฅํ•˜๊ฒŒ ํ•œ๋‹ค๊ณ  ์•Œ๋ ค์ ธ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๋ฐฉ๋ฒ•์„ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ถ€์žฌ์˜ ์„ค๊ณ„์— ์ ์šฉํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์„ ์ •ํ•œ

์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ ํ•ฉ์„ฑ ํŒ๋‹จ ๋ฐ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ถ€์žฌ์˜ ๊ฐ•๋„์— ๊ฐ€์žฅ ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋ฅผ ์ •ํ™•ํ•˜๊ฒŒ ๊ฒฐ์ •ํ•˜์—ฌ์•ผ ํ•œ๋‹ค.

ํ˜„์žฌ๊นŒ์ง€ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋ฅผ ๊ฒฐ์ •ํ•˜๊ธฐ ์œ„ํ•œ ๋งŽ์€ ์‹คํ—˜ ๋ฐ ํ•ด์„์  ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์–ด ์™”์œผ๋ฉฐ, ์ฃผ์š”์„ค๊ณ„๊ธฐ์ค€ ๋ฐ ์—ฐ๊ตฌ๋ฌธํ—Œ์„ ํ†ตํ•˜์—ฌ ์—ฌ๋Ÿฌ ์ข…๋ฅ˜์˜ ์œ ํšจ๊ฐ•๋„ ์‹์ด ์ œ์•ˆ๋˜์—ˆ๋‹ค(Thulimann, 1976; Nielsen et al., 1978; Ramirez and Breen, 1983; Marti, 1985; Schlaich et al., 1987; Alshegeir, 1992; Bergmeister et al., 1993; MacGregor, 1997; Collins and Mitchell, 2001; EC2, 2004; FIB, 2010; AASHTO, 2010; ACI 318-11, 2011). ๊ทธ๋ฆฌ๊ณ  ์ œ์•ˆ๋œ ์œ ํšจ๊ฐ•๋„ ์‹์˜ ํƒ€๋‹น์„ฑ ๊ฒ€์ฆ์— ๊ด€ํ•œ ๋ช‡๋ช‡ ์—ฐ๊ตฌ๊ฐ€ ์ˆ˜ํ–‰๋˜์—ˆ๋‹ค(Yang et al., 2003; Jeun and Yun, 2010). ๊ทธ๋Ÿฌ๋‚˜ ์ œ์•ˆ๋œ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์€ ๋ช‡๋ช‡ ํŠน์ •ํ•œ ํ•˜์ค‘ ๋ฐ ํ˜•์ƒ ์กฐ๊ฑด์„ ๊ฐ–๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์˜ ์‹คํ—˜ ๋ฐ ์ˆ˜์น˜ํ•ด์„ ๊ฒฐ๊ณผ์— ๋ฐ”ํƒ•์„ ๋‘” ๊ฒƒ์œผ๋กœ, ์ฝ”๋ฒจ์˜ ๊ธฐํ•˜ํ•™์  ํ˜•์ƒ ๋ฐ ์—ฌ๋Ÿฌ ์„ค๊ณ„๋ณ€์ˆ˜์— ๋”ฐ๋ผ ๋ณต์žกํ•œ ํŒŒ๊ดด๊ฑฐ๋™์„ ๋ณด์ด๋Š” ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ํ•ด์„ ๋ฐ ์„ค๊ณ„์— ๊ทธ๋Œ€๋กœ ์‚ฌ์šฉํ•˜๋Š” ๊ฒƒ์€ ์ ์ ˆํ•˜์ง€ ์•Š๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์„œ์—์„œ ์ œ์•ˆ๋œ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ Yun and Ramirez (1994), Hwang et al. (2000), Collins and Mitchell (2001), ACI 445 (2002), Chae (2012), Korean Concrete Institute (2013) ๋“ฑ์„ ๋น„๋กฏํ•œ ์—ฌ๋Ÿฌ ์ €์„œ ๋ฐ ์—ฐ๊ตฌ๋ฌธํ—Œ์—์„œ ์ œ์•ˆ๋œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๋Œ€ํ‘œ์ ์ธ ์„ธ ์ข…๋ฅ˜์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์— ์ ์šฉํ•˜์—ฌ Kriz and Raths (1965), Mattock et al. (1976), ๊ทธ๋ฆฌ๊ณ  Foster et al. (1996)์— ์˜ํ•ด ํŒŒ๊ดด์‹คํ—˜์ด ์ˆ˜ํ–‰๋œ 243๊ฐœ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ํŒŒ๊ดด๊ฐ•๋„๋ฅผ ํ‰๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ๊ฐ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์˜ ์ ํ•ฉ์„ฑ์„ ๋ถ„์„ํ•˜์˜€๋‹ค. ๋˜ํ•œ 2์ฐจ์› ์‘๋ ฅ์„ ๋ฐ›๋Š” ๋ฌด๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ฃผ์‘๋ ฅ ์ƒํƒœ ๋ฐ ์ฒ ๊ทผ์— ์˜ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ตฌ์†ํšจ๊ณผ๋ฅผ ๊ณ ๋ คํ•˜๋Š” Yun (2005)์˜ ๋ฐฉ๋ฒ•์— ์ฝ˜ํฌ๋ฆฌํŠธ ์••์ถ•๊ฐ•๋„์˜ ์˜ํ–ฅ์„ ์ถ”๊ฐ€ํ•˜์—ฌ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ธฐํ•˜ํ•™์  ํ˜•์ƒ, ์ˆ˜์ง ๋ฐ ์ˆ˜ํ‰ ์ง‘์ค‘ํ•˜์ค‘์˜ ์กฐํ•ฉ ๋น„, ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„, ๊ทธ๋ฆฌ๊ณ  ํœจ์ฒ ๊ทผ ๋ฐ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ ๋น„ ๋“ฑ์˜ ์ฃผ์š” ์„ค๊ณ„๋ณ€์ˆ˜๋“ค์˜ ์˜ํ–ฅ์„ ์ •ํ™•ํžˆ ๋ฐ˜์˜ํ•  ์ˆ˜ ์žˆ๋Š” ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์„ ๊ฐœ๋ฐœ, ์ œ์•ˆํ•˜์˜€์œผ๋ฉฐ, ์ œ์•ˆํ•œ ์‹์˜ ์ ํ•ฉ์„ฑ์„ ๊ฒ€์ฆํ•˜์˜€๋‹ค.

PIC13B0.jpg

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(a) Arch Mechanism

(b) Bottle-shaped Mechanism

(c) Combined Mechanism

Fig. 1. Strut-Tie Models for Reinforced Concrete Corbels

2. ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ

ACI 318-11 (2011) ๋ฐ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๊ธฐ์ค€(2012)์€ ์ „๋‹จ๊ฒฝ๊ฐ„๋น„(PIC1634.gif)๊ฐ€ 2 ์ดํ•˜์ธ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์€ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๋ฐฉ๋ฒ•์„ ์ด์šฉํ•˜์—ฌ ์„ค๊ณ„ํ•  ์ˆ˜ ์žˆ๋„๋ก ๊ทœ์ •ํ•˜๊ณ  ์žˆ๋‹ค. ์ฝ”๋ฒจ์˜ ์„ค๊ณ„๋ฅผ ์œ„ํ•œ ๋‹ค์–‘ํ•œ ํ˜•ํƒœ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์ด ์„ ์ •๋  ์ˆ˜ ์žˆ์œผ๋‚˜, ํ˜„์žฌ๊นŒ์ง€ ์ œ์•ˆ๋œ ์ฝ”๋ฒจ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์€ ํฌ๊ฒŒ ์„ธ ์ข…๋ฅ˜๋กœ ๋ถ„๋ฅ˜ํ•  ์ˆ˜ ์žˆ๋‹ค. Fig. 1(a)์˜ ๋‚ด๋ฏผ๋ถ€๋ถ„์˜ ํ•˜์ค‘์ ๊ณผ ๊ธฐ๋‘ฅ์„ ํ•˜๋‚˜์˜ ์ŠคํŠธ๋Ÿฟ์œผ๋กœ ์—ฐ๊ฒฐํ•œ ์•„์น˜ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ, Fig. 1(b)์˜ ํ•˜์ค‘์ ๊ณผ ๊ธฐ๋‘ฅ์„ ์ˆ˜ํ‰ ํƒ€์ด๋ฅผ ํฌํ•จํ•˜๋Š” ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ, ๊ทธ๋ฆฌ๊ณ  Fig. 1(c)์˜ ์•„์น˜ ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์กฐํ•ฉํ•œ ๋ณตํ•ฉ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์ด ๊ทธ๊ฒƒ์ด๋‹ค.

Figs. 1(a) and 1(b)์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ŠคํŠธ๋Ÿฟ๊ณผ ํƒ€์ด๋Š” ๊ทธ๋“ค์˜ ๊ฐ•์„ฑ์— ๊ด€๊ณ„์—†์ด ์ผ์ •ํ•œ ๋‹จ๋ฉด๋ ฅ์„ ๊ฐ€์ง€๋‚˜, Fig. 1(c)์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ŠคํŠธ๋Ÿฟ๊ณผ ํƒ€์ด๋Š” ๊ฐ ์ŠคํŠธ๋Ÿฟ ๋ฐ ํƒ€์ด์˜ ๊ฐ•์„ฑ์— ๋”ฐ๋ผ ๋‹จ๋ฉด๋ ฅ์ด ๋‹ฌ๋ผ์ง„๋‹ค. ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๋ฐฉ๋ฒ•์— ์ ‘๋ชฉ์‹œ์ผœ ์ „๋‹จ๊ฒฝ๊ฐ„๋น„๊ฐ€ 1 ์ดํ•˜์ธ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์„ ์„ค๊ณ„ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ Chae (2012)๋Š” ์•„์น˜ ๋ฉ”์ปค๋‹ˆ์ฆ˜๊ณผ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์ด ๋ถ€๋‹ดํ•˜๋Š” ์ˆ˜ํ‰๋ ฅ์˜ ํฌ๊ธฐ๋ฅผ ํ•˜์ค‘๋ถ„๋ฐฐ์œจ๋กœ ๊ทœ์ •ํ•˜์—ฌ ์ œ์‹œํ•˜์˜€๋‹ค. ์ œ์‹œํ•œ ํ•˜์ค‘๋ถ„๋ฐฐ์œจ์€ 1์ฐจ ๋ถ€์ •์ • ํŠธ๋Ÿฌ์Šค ๊ตฌ์กฐ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ •์ •์˜ ํŠธ๋Ÿฌ์Šค ๊ตฌ์กฐ๋กœ ๋ณ€ํ™˜์‹œํ‚ค๋ฏ€๋กœ, ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ์ฒ ๊ทผํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ํ•ด์„ ๋ฐ ์„ค๊ณ„ ์‹œ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ๊ฐ ์ ˆ์ ์—์„œ ํž˜์— ๊ด€ํ•œ ํ‰ํ˜•์กฐ๊ฑด์„ ์ ์šฉํ•˜์—ฌ ๋ชจ๋“  ์ŠคํŠธ๋Ÿฟ๊ณผ ํƒ€์ด์˜ ๋‹จ๋ฉด๋ ฅ์„ ๊ตฌํ•  ์ˆ˜ ์žˆ๊ฒŒ ํ•œ๋‹ค. ์ œ์‹œํ•œ ํ•˜์ค‘๋ถ„๋ฐฐ์œจ PIC1683.gif(%)๋Š” ์ฝ”๋ฒจ์— ์ž‘์šฉํ•˜๋Š” ์ˆ˜์ง์˜ ์ง‘์ค‘ํ•˜์ค‘ PIC16A3.gif์™€ Fig. 1(c)์˜ ์ˆ˜ํ‰ํƒ€์ด PIC16B4.gif์˜ ๋‹จ๋ฉด๋ ฅ์˜ ๋น„๋กœ์„œ, ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

PIC1732.gif  (1)

์—ฌ๊ธฐ์„œ, PIC1762.gif, PIC1772.gif, PIC1773.gif๋Š” ์ฝ”๋ฒจ์˜ ์ฃผ์š” ์„ค๊ณ„๋ณ€์ˆ˜์— ๋”ฐ๋ฅธ ํ•˜์ค‘๋ถ„๋ฐฐ์œจ์˜ ๋ณ€ํ™”๋ฅผ ๊ณ ๋ คํ•˜๋Š” ๋ณ€์ˆ˜๋กœ์„œ, ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ •์˜ํ•˜์˜€๋‹ค.

PIC1BBA.gif 

(2)

์œ„ ์‹์—์„œ, PIC1BCB.gif๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋ฅผ, PIC1BEB.gif(=PIC1C2B.gif, PIC1C6A.gif=์ฃผ์ธ์žฅ ์ฒ ๊ทผ์˜ ๋‹จ๋ฉด์ , PIC1C8A.gif=์ฝ”๋ฒจ์˜ ํญ, PIC1CAB.gif=์œ ํšจ๊นŠ์ด)๋Š” ์ฃผ์ธ์žฅ ์ฒ ๊ทผ๋น„๋ฅผ, PIC1CAC.gif(=PIC1CDB.gif)๋Š” ์ฝ”๋ฒจ์— ์ž‘์šฉํ•˜๋Š” ์ˆ˜์ง๋ ฅ์— ๋Œ€ํ•œ ์ˆ˜ํ‰๋ ฅ์˜ ๋น„๋ฅผ, ๊ทธ๋ฆฌ๊ณ  PIC1CFC.gif(=PIC1D1C.gif, PIC1D3C.gif=์ฃผ์ธ์žฅ ์ฒ ๊ทผ์˜ ํ•ญ๋ณต๊ฐ•๋„)์€ ์ฃผ์ธ์žฅ ์ฒ ๊ทผ์˜ ์ตœ์†Œ์ฒ ๊ทผ๋น„์ด๋‹ค.

3. ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹

3.1 ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์˜ ์œ ํšจ๊ฐ•๋„ ์‹

์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ PIC1D4D.gif๋Š” ์ผ๋ฐ˜์ ์œผ๋กœ ์‹ค๋ฆฐ๋” ์ฝ˜ํฌ๋ฆฌํŠธ ๊ณต์‹œ์ฒด์˜ ์••์ถ•๊ฐ•๋„ PIC1D6D.gif์˜ ํ•จ์ˆ˜๋กœ ๋‚˜ํƒ€๋‚ธ๋‹ค. EC2 (2004)๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ PIC1D7E.gif(=PIC1D9E.gif)๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ œ์‹œํ•˜์˜€๋‹ค.

PIC1DAF.gif (3)

์—ฌ๊ธฐ์„œ, PIC1DCF.gif๋Š” ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜๋กœ์„œ ์ŠคํŠธ๋Ÿฟ ์ถ•์˜ ์ง๊ฐ๋ฐฉํ–ฅ์œผ๋กœ ์ธ์žฅ์‘๋ ฅ์ด ์—†์„ ๊ฒฝ์šฐ๋Š” 1.0์„, ์žˆ์„ ๊ฒฝ์šฐ๋Š” PIC1E1E.gif์ด๋‹ค. Eq. (3)์—์„œ, PIC1E3E.gif์˜ ๋‹จ์œ„๋Š” MPa์ด๋‹ค.

FIB (2010)๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ œ์‹œํ•˜์˜€๋‹ค.

PIC1ECC.gif (4)

์—ฌ๊ธฐ์„œ, PIC1EDC.gif๋Š” ์‹ค๋ฆฐ๋” ์••์ถ•๊ฐ•๋„์˜ ํŠน์„ฑ ๊ฐ’์ด๋ฉฐ, PIC1EFD.gif(=PIC1F4C.gif, PIC1F5C.gif= ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ฐ•๋„์˜ ๋ณ€ํ™”๋ฅผ ๊ณ ๋ คํ•˜๋Š” ๊ณ„์ˆ˜, PIC1F9C.gif= ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๋ถ€๋ถ„์•ˆ์ „๊ณ„์ˆ˜)๋Š” ์‹ค๋ฆฐ๋” ์••์ถ•๊ฐ•๋„์˜ ์„ค๊ณ„ ๊ฐ’์ด๋‹ค. ๋˜ํ•œ PIC1FCC.gif๋Š” ๊ฐ•๋„๊ฐ์†Œ๊ณ„์ˆ˜๋กœ์„œ, ๊ต๋ž€๋˜์ง€ ์•Š๋Š” 1์ถ• ์••์ถ•์‘๋ ฅ ๋˜๋Š” 2์ถ• ์••์ถ•์‘๋ ฅ์„ ๋ฐ›๋Š” ์ŠคํŠธ๋Ÿฟ์˜ ๊ฒฝ์šฐ๋Š” 1.0, ์ŠคํŠธ๋Ÿฟ์˜ ์ถ•๋ฐฉํ–ฅ๊ณผ ํ‰ํ–‰ํ•˜๊ฒŒ ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜๊ณ  ๊ท ์—ด ์ง๊ฐ๋ฐฉํ–ฅ์œผ๋กœ ์ธ์žฅ์„ ๋ฐ›๋Š” ์ฒ ๊ทผ์ด ์žˆ๋Š” ์ŠคํŠธ๋Ÿฟ์˜ ๊ฒฝ์šฐ๋Š” 0.75, ๊ทธ๋ฆฌ๊ณ  ์ŠคํŠธ๋Ÿฟ์˜ ์ถ•๋ฐฉํ–ฅ๊ณผ ๋น„์Šค๋“ฌํ•œ ๋ฐฉํ–ฅ์œผ๋กœ ์ฒ ๊ทผ์ด ์žˆ๋Š” ์ŠคํŠธ๋Ÿฟ์˜ ๊ฒฝ์šฐ๋Š” 0.55์ด๋‹ค. ์ด ์„ค๊ณ„๊ธฐ์ค€์€ PIC20B7.gif์˜ ๊ฐ’์„ ์ƒ๊ธฐ์˜ ๊ฐ ๊ฒฝ์šฐ์— ๋Œ€ํ•˜์—ฌ 1.0, 0.8, 0.55๋กœ ์ œํ•œํ•˜๊ณ  ์žˆ๋‹ค.

AASHTO (2010)๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ Vecchio and Collins (1982)์˜ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์— ๊ทผ๊ฑฐํ•˜์—ฌ ์ œ์‹œํ•˜์˜€๋‹ค. Vecchio and Collins๋Š” ๊ท ์ผํ•œ ์‘๋ ฅ๊ณผ ๋ณ€ํ˜•์„ ๊ฒช๋Š” ํฐ ์ฝ˜ํฌ๋ฆฌํŠธ ํŒจ๋„์˜ ์‹œํ—˜๊ฒฐ๊ณผ์— ๊ทผ๊ฑฐํ•˜์—ฌ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ ์œ ๋„ํ•˜์˜€๋Š”๋ฐ, ์ด ์‹์€ ์ŠคํŠธ๋Ÿฟ์— ํ‰ํ–‰ํ•œ ๊ท ์—ด๋“ค์„ ์„ค๋ช…ํ•˜๋Š” ๊ฒฝํ—˜์  ์ƒ์ˆ˜๋ฅผ ํฌํ•จํ•˜๊ณ  ์žˆ๋‹ค. CSA (2004)์—์„œ๋Š” ๊ทธ๋“ค์˜ ์‹์„ ์•ฝ๊ฐ„ ๋‹จ์ˆœํ™”ํ•œ ๋‹ค์Œ์˜ Eq. (5)๋ฅผ ์ฑ„ํƒํ•˜์˜€์œผ๋ฉฐ, AASHTO๋Š” Eq. (5)๋ฅผ ์ฑ„ํƒํ•˜์˜€์œผ๋‚˜ ๊ทธ ์ตœ๋Œ€๊ฐ’์„ PIC20C8.gif์œผ๋กœ ์ œํ•œํ•˜์˜€๋‹ค.

PIC2165.gif (5)

์—ฌ๊ธฐ์„œ, PIC2185.gif์˜ ๋‹จ์œ„๋Š” MPa์ด๋ฉฐ, PIC21A6.gif์€ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์— ์ˆ˜์ง์œผ๋กœ ๋ฐฐ์น˜๋œ ์ฒ ๊ทผ์˜ ํ‰๊ท  ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์ด๋‹ค. ์ผ๋ฐ˜์ ์œผ๋กœ ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ๋งŽ์€ D-์˜์—ญ์—์„œ PIC21E5.gif์„ ์ถ”์ •ํ•˜๋Š” ํ•ฉ๋ฆฌ์ ์ธ ๋ฐฉ๋ฒ•์ด ์—†๊ธฐ ๋•Œ๋ฌธ์— PIC2205.gif์„ ์ฒ ๊ทผ์˜ ์ธ์žฅ๋ณ€ํ˜•๋ฅ ์˜ ํ•จ์ˆ˜๋กœ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ œ์‹œํ•˜์˜€๋‹ค.

PIC22F1.gif (6)

์—ฌ๊ธฐ์„œ, PIC2321.gif๋Š” ์ŠคํŠธ๋Ÿฟ ์ถ•์—์„œ PIC2331.gif์˜ ๊ฐ์œผ๋กœ ์ŠคํŠธ๋Ÿฟ์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ์ธ์žฅ ํƒ€์ด์˜ ํ‰๊ท  ์ธ์žฅ๋ณ€ํ˜•๋ฅ ๋กœ์„œ, ์„ค๊ณ„๊ธฐ์ค€์„œ๋Š” PIC240D.gif๋ฅผ ์ฒ ๊ทผ์˜ ํ•ญ๋ณต๋ณ€ํ˜•๋ฅ ๋กœ ์ œ์‹œํ•˜์˜€๋‹ค.

ACI 318-11 (2011)์€ ์ŠคํŠธ๋Ÿฟ ์ค‘๊ฐ„์ง€์ ์—์„œ์˜ ๋‹จ๋ฉดํ˜•์ƒ ๋ฐ ์ŠคํŠธ๋Ÿฟ ์–‘๋‹จ์—์„œ์˜ ๋‹จ๋ฉดํ˜•์ƒ๊ณผ์˜ ๊ด€๊ณ„์™€ ๋ฐฐ์น˜ํ•˜๋Š” ์ฒ ๊ทผ์˜ ์–‘์„ ๊ณ ๋ คํ•˜์—ฌ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ œ์•ˆํ•˜์˜€๋‹ค.

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์—ฌ๊ธฐ์„œ, PIC244D.gif๋Š” ๊ท ์—ด ๋ฐ ๊ตฌ์†์ฒ ๊ทผ์ด ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜๊ธฐ์œ„ํ•œ ๊ณ„์ˆ˜๋กœ์„œ, ์ŠคํŠธ๋Ÿฟ ์ค‘๊ฐ„์ง€์ ์—์„œ์˜ ๋‹จ๋ฉด์ ์ด ์ŠคํŠธ๋Ÿฟ ์–‘๋‹จ์—์„œ์˜ ๋‹จ๋ฉด์ ๊ณผ ๊ฐ™์„ ๋•Œ๋Š” 1.0, ์ŠคํŠธ๋Ÿฟ ์ค‘๊ฐ„์ง€์ ์—์„œ์˜ ๋‹จ๋ฉด์ ์ด ์ŠคํŠธ๋Ÿฟ ์–‘๋‹จ์—์„œ์˜ ๋‹จ๋ฉด์ ๋ณด๋‹ค ํฌ๊ณ  ์ŠคํŠธ๋Ÿฟ์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ์ธ์žฅ์ฒ ๊ทผ์˜ ์‘๋ ฅ ๋ฐ ๋ฐฐ์น˜์— ๊ด€ํ•œ Eq. (8)์„ ๋งŒ์กฑํ•  ๊ฒฝ์šฐ๋Š” 0.75, ๊ทธ๋ฆฌ๊ณ  ์ŠคํŠธ๋Ÿฟ ์ค‘๊ฐ„์ง€์ ์—์„œ์˜ ๋‹จ๋ฉด์ ์ด ์ŠคํŠธ๋Ÿฟ ์–‘๋‹จ์—์„œ์˜ ๋‹จ๋ฉด์ ๋ณด๋‹ค ํฌ๊ณ  ์ธ์žฅ์ฒ ๊ทผ์˜ ์‘๋ ฅ ๋ฐ ๋ฐฐ์น˜์— ๊ด€ํ•œ Eq. (8)์„ ๋งŒ์กฑํ•˜์ง€ ๋ชปํ•  ๊ฒฝ์šฐ๋Š” 0.60PIC246E.gif (์—ฌ๊ธฐ์„œ PIC24BD.gif๋Š” ์ผ๋ฐ˜์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ฒฝ์šฐ 1.0, sand-๊ฒฝ๋Ÿ‰์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ฒฝ์šฐ 0.85, ๊ฒฝ๋Ÿ‰์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ฒฝ์šฐ 0.75)์˜ ๊ฐ’์„ ๊ฐ–๋Š”๋‹ค. ๋˜ํ•œ PIC24DD.gif๋Š” ์ธ์žฅ๋ถ€์žฌ์—์„œ์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ๊ฒฝ์šฐ ๋ฐ ๊ธฐํƒ€์˜ ๋ชจ๋“  ๊ฒฝ์šฐ์— ๊ฐ๊ฐ 0.40 ๋ฐ 0.60์˜ ๊ฐ’์„ ๊ฐ–๋Š”๋‹ค.

PIC254B.gif (8)

์—ฌ๊ธฐ์„œ, PIC256C.gif ๋ฐ PIC257C.gif๋Š” ๊ฐ๊ฐ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ์ˆ˜์ง์ฒ ๊ทผ๊ณผ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์ด ์ด๋ฃจ๋Š” ๊ฐ ๋ฐ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ์ˆ˜ํ‰์ฒ ๊ทผ๊ณผ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์ด ์ด๋ฃจ๋Š” ๊ฐ์„, PIC25AC.gif ๋ฐ PIC25AD.gif๋Š” ๊ฐ๊ฐ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ์ˆ˜์ง์ฒ ๊ทผ์˜ ์ค‘์‹ฌ๊ฐ„ ๊ฑฐ๋ฆฌ ๋ฐ ์ˆ˜ํ‰์ฒ ๊ทผ์˜ ์ค‘์‹ฌ๊ฐ„ ๊ฑฐ๋ฆฌ๋ฅผ, ๊ทธ๋ฆฌ๊ณ  PIC25DD.gif ๋ฐ PIC25DE.gif๋Š” ๊ฐ๊ฐ PIC261E.gif ๋ฐ PIC261F.gif ๋‚ด์—์„œ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์„ ๊ฐ€๋กœ์ง€๋ฅด๋Š” ์ˆ˜์ง์ฒ ๊ทผ ๋ฐ ์ˆ˜ํ‰์ฒ ๊ทผ ํ•˜๋‚˜์˜ ๋‹จ๋ฉด์ ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

3.2 ํ˜„ ์—ฐ๊ตฌ์˜ ์œ ํšจ๊ฐ•๋„ ์‹

Yun (2005)์€ 2์ฐจ์› ์‘๋ ฅ์„ ๋ฐ›๋Š” ๋ฌด๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์ฃผ์‘๋ ฅ ์ƒํƒœ, 2์ฐจ์› ์••์ถ•์ฃผ์‘๋ ฅ ํ๋ฆ„๊ณผ ์ŠคํŠธ๋Ÿฟ ์ถ•๋ฐฉํ–ฅ๊ณผ์˜ ์ฐจ์ด ๊ฐ, ๊ทธ๋ฆฌ๊ณ  ์ฒ ๊ทผ์— ์˜ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ตฌ์†ํšจ๊ณผ ๋“ฑ์„ ์ด์šฉํ•˜์—ฌ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋ฅผ ๊ฒฐ์ •ํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ์ œ์•ˆํ•˜์˜€๋‹ค. ์ด ๋ฐฉ๋ฒ•์—์„œ๋Š” ํ‰๋ฉด์‘๋ ฅ ํ˜น์€ ํ‰๋ฉด๋ณ€ํ˜•๋ฅ  ์œ ํ•œ์š”์†Œํ•ด์„์œผ๋กœ๋ถ€ํ„ฐ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์ด ์œ„์น˜ํ•œ ๊ณณ์˜ ํ•œ ์œ ํ•œ์š”์†Œ์˜ ์ฃผ์‘๋ ฅ PIC262F.gif ๋ฐ PIC2640.gif๋ฅผ ์ฐพ๊ณ , ๋ฌด๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํŒŒ๊ดดํฌ๋ฝ์„ ์œผ๋กœ๋ถ€ํ„ฐ ์ด ์š”์†Œ์˜ ์ฃผ์‘๋ ฅ์— ํ•ด๋‹น๋˜๋Š” PIC2650.gif ์ฆ‰ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ ์œ„์น˜์— ๋†“์ธ ์œ ํ•œ์š”์†Œ์˜ ์œ ํšจ๊ฐ•๋„ PIC2661.gif๋ฅผ ์ฐพ๋Š”๋‹ค. ์—ฌ๊ธฐ์„œ, ์ฃผ์‘๋ ฅ PIC2672.gif ๋ฐ PIC2682.gif๋Š” ๊ฐ๊ฐ PIC2693.gif ๋ฐ PIC26A4.gif๋ณด๋‹ค ์ž‘๊ฑฐ๋‚˜ ๊ฐ™๋‹ค. ์ผ๋ฐ˜์ ์œผ๋กœ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์€ ์—ฌ๋Ÿฌ ๊ฐœ์˜ ํ‰๋ฉด๊ณ ์ฒด ์œ ํ•œ์š”์†Œ์— ๊ฑธ์ณ์žˆ์œผ๋ฏ€๋กœ, ๋™์ผํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ฐ ์œ ํ•œ์š”์†Œ๋“ค์˜ PIC26C4.gif๋ฅผ ๊ฒฐ์ •ํ•œ๋‹ค. ๊ฒฐ์ •ํ•œ ์—ฌ๋Ÿฌ ์œ ํ•œ์š”์†Œ๋“ค์˜ PIC26E4.gif๊ฐ’ ์ค‘์—์„œ ์ด๋“ค ๊ฐ’์˜ ํ‘œ์ค€ํŽธ์ฐจ ๋ฒ”์œ„ ๋‚ด์— ๋“ค์–ด์˜ค๋Š” ๊ฐ’๋“ค์„ ์‚ฐ์ˆ ํ‰๊ท ํ•œ ๊ฐ’์„ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ PIC2704.gif๋กœ ์ทจํ•œ๋‹ค. ๋งŒ์•ฝ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์ด ์œ„์น˜ํ•œ ์œ ํ•œ์š”์†Œ์˜ ์••์ถ•์ฃผ์‘๋ ฅ์˜ ๊ฐ์ด ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ๋ฐฉํ–ฅ๊ณผ PIC2715.gif ๊ฐ๋„๋งŒํผ ์ฐจ์ด๊ฐ€ ๋‚œ๋‹ค๋ฉด ์ด ์œ ํ•œ์š”์†Œ์˜ ์œ ํšจ๊ฐ•๋„๋Š” ์ฃผ์‘๋ ฅ์˜ ์ถ•๋ณ€ํ™˜ ์‹์„ ์ด์šฉํ•˜์—ฌ ๊ฐ์†Œ์‹œํ‚จ๋‹ค.

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PIC2784.gif ๋ฐ PIC27A5.gif๋ฅผ ๊ฒฐ์ •ํ•˜๊ธฐ ์œ„ํ•œ ์œ„ ๊ณผ์ •์—์„œ๋Š” ์ฒ ๊ทผ์˜ ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜์ง€ ์•Š์€ ์ƒํƒœ์—์„œ ๋ฌด๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์œ ํ•œ์š”์†Œํ•ด์„์„ ํ†ตํ•ด ๊ฒฐ์ •ํ•œ ์ฃผ์‘๋ ฅ์„ ์ด์šฉํ•˜์˜€๋‹ค. ๋”ฐ๋ผ์„œ ์ฒ ๊ทผ์— ์˜ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์†์˜ ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์ฃผ์‘๋ ฅ PIC27C5.gif ๋ฐ PIC27E5.gif์˜ ๊ฒฐ์ • ์‹œ ์ฒ ๊ทผํƒ€์ด์˜ ๋‹จ๋ฉด๋ ฅ์„ ์™ธ๋ถ€์˜ ํ•˜์ค‘์œผ๋กœ ์ž‘์šฉ์‹œ์ผœ ๋ฌด๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์œ ํ•œ์š”์†Œํ•ด์„์„ ๋‹ค์‹œ ์ˆ˜ํ–‰ํ•œ๋‹ค. ์ด์™€ ๊ฐ™์€ ๊ณผ์ •์„ 2~3์ฐจ๋ก€ ๋ฐ˜๋ณตํ•˜์—ฌ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋ฅผ ์ตœ์ข…์ ์œผ๋กœ ๊ฒฐ์ •ํ•œ๋‹ค.

์ƒ๊ธฐ ๊ณผ์ •์€ ๋ฐ˜๋ณต์ ์ธ ์ˆ˜์น˜ํ•ด์„๊ณผ ๋งŽ์€ ์–‘์˜ ์ž‘์—…์ด ํ•„์š”ํ•˜๋ฏ€๋กœ, ์ด๋ฅผ ์œ„ํ•œ ์ „๋ฌธ ํ”„๋กœ๊ทธ๋žจ์„ ์‚ฌ์šฉํ•˜์ง€ ์•Š๋Š”๋‹ค๋ฉด ์‹ค๋ฌด ์ ์šฉ์— ํฐ ํ•œ๊ณ„๊ฐ€ ์žˆ๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” Yun (2005)์˜ ๋ฐฉ๋ฒ•์„ PIC2834.gif ๋ฒ”์œ„์˜ ์ „๋‹จ๊ฒฝ๊ฐ„๋น„, PIC28B2.gif ๋ฒ”์œ„์˜ ํœจ์ฒ ๊ทผ๋น„, PIC28D2.gifPIC2941.gif ๋ฒ”์œ„์˜ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ ๋น„, ๊ทธ๋ฆฌ๊ณ  PIC2980.gifPIC29B0.gif ๋ฒ”์œ„์˜ ์ˆ˜์งํ•˜์ค‘์— ๋Œ€ํ•œ ์ˆ˜ํ‰ํ•˜์ค‘์˜ ๋น„ ๋“ฑ์„ ๊ฐ–๋Š” Fig. 4์˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์— ์ ์šฉํ•˜์—ฌ ์„ธ ์ข…๋ฅ˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ๋ชจ๋“  ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ๊ฐ’์„ ๊ตฌํ•˜์˜€๋‹ค. ์—ฌ๊ธฐ์„œ, PIC29F0.gif ๋ฐ PIC2A20.gif๋Š” ์‹ค์ œ๋กœ ์ฝ”๋ฒจ์— ๋ฐฐ์น˜๋œ(๋ ) ํœจ ๋ฐ ์ˆ˜ํ‰์ „๋‹จ ์ฒ ๊ทผ๋Ÿ‰์ด๋ฉฐ, PIC2A40.gif (=PIC2A60.gifPIC2ACE.gif, PIC2AFE.gif, PIC2B1F.gif=์ฒ ๊ทผ์˜ ํ•ญ๋ณต๊ฐ•๋„)๋Š” ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์— ์ž‘์šฉํ•˜๋Š” ์ˆ˜์งํ•˜์ค‘ PIC2B2F.gif ๋ฐ ์ˆ˜ํ‰ํ•˜์ค‘ PIC2B40.gif์— ๋Œ€ํ•œ ํ•„์š”์ฒ ๊ทผ๋Ÿ‰์„, PIC2B50.gif(=PIC2BA0.gif)๋Š” ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์ด ๋ชจ๋“  ์ „๋‹จ๋ ฅ์„ ๋ถ€๋‹ดํ•  ๋•Œ ํ•„์š”ํ•œ ์ˆ˜ํ‰์ „๋‹จ ์ฒ ๊ทผ๋Ÿ‰์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์ด ์—ฐ๊ตฌ์˜ ์ฃผ์š” ์„ค๊ณ„๋ณ€์ˆ˜์˜ ๋ฒ”์œ„์—์„œ ์ˆ˜๋งŽ์€ ์„ค๊ณ„๋ณ€์ˆ˜์˜ ์กฐํ•ฉ์„ ๊ฐ–๋Š” ์ฝ”๋ฒจ์„ ๋Œ€์ƒ์œผ๋กœ Fig. 2์˜ ๋ชจ๋“  ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ PIC2BC0.gif๋ฅผ ๊ตฌํ•˜์˜€๋‹ค. ํ•œ ์˜ˆ๋กœ, Fig. 3์€ Fig. 2์˜ ๊ฒฝ์‚ฌ ์ŠคํŠธ๋Ÿฟ B, C, D์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC2BD0.gif (=PIC2BE1.gif, PIC2C01.gif=Yun (2005)์˜ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•œ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„)๋ฅผ ํœจ์ฒ ๊ทผ ๋น„๊ฐ€ 0.4 ๋ฐ 1.0์ธ ๊ฒฝ์šฐ์— ๋Œ€ํ•˜์—ฌ ๊ตฌํ•œ ๊ฒƒ์ด๋‹ค. ๋ชจ๋“  ์„ค๊ณ„๋ณ€์ˆ˜์˜ ์กฐํ•ฉ ํ•˜์—์„œ ๊ณก์„ ์กฐ์ •์„ ํ†ตํ•ด ๊ฒฐ์ •ํ•œ ๊ฒฝ์‚ฌ ์ŠคํŠธ๋Ÿฟ B, C, D์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC2C12.gif๋Š” Eq. (10)๊ณผ ๊ฐ™์ด ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ๊ฒฝ์‚ฌ ์ŠคํŠธ๋Ÿฟ F ๋ฐ G์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC2C13.gif์€ ๋ชจ๋“  ์„ค๊ณ„๋ณ€์ˆ˜์˜ ์กฐํ•ฉ์— ๋Œ€ํ•˜์—ฌ 0.95~1.0์˜ ๋ฒ”์œ„์˜ ๊ฐ’์„ ๋ณด์˜€์œผ๋‚˜, ์ฝ”๋ฒจ์˜ ๋ณด์ˆ˜์ ์ธ ์„ค๊ณ„๋ฅผ ์œ„ํ•˜์—ฌ 0.95๋กœ ์ทจํ•  ์ˆ˜ ์žˆ๋‹ค.

PIC2C52.jpg

Fig. 2. Numerical Analysis Model for Determining Effective Strengths of Concrete Struts

PIC2CA2.gif (10)

PIC2D10.jpg

PIC2D8E.jpg

(a) Strut B

PIC2E0C.jpg

PIC2E8A.jpg

(b) Strut C

PIC2F27.jpg

PIC2F96.jpg

(c) Strut D

Fig. 3. Coefficients of Effective Strengths of Concretes Strut Associated with Primary Design Variables

Table 1. Specification of Reinforced Concrete Corbels tested to Failure

Investigators

No. of Corbels

b(mm)

c(mm)

d(mm)

h(mm)

PIC2FD5.gif(MPa)

PIC3005.gif(MPa)

a/d

PIC3016.gif(%)

PIC3036.gif

Kriz & Raths (1965)

185

203-406

152-610

307-1059

356-1143

14.6-46.1

293-498

0.11-0.62

0.21-2.53

0.05-0.56

Mattock et al. (1976)

28

152

152-330

221-231

254

23.8-30.7

321-447

0.22-1.02

0.75-3.17

0.22-0.88

Foster et al. (1996)

30

125-150

300-550

450-740

600-800

45.0-105.0

415-495

0.30-1.00

0.58-5.00

0.08-1.02

Total

243

125-406

152-610

221-1059

254-1143

14.6-105.0

293-495

0.11-1.02

0.21-5.00

0.05-1.02

b, c, d, h: width, overhanging length, effective depth, height; PIC3066.gif: compressive strength of concrete; PIC3086.gif: yield strength of steel; a/d: shear span-to-effective depth ratio; PIC3097.gif: flexural reinforcement ratio; PIC30B7.gif: balanced flexural reinforcement ratio

์—ฌ๊ธฐ์„œ, ๊ณ„์ˆ˜ PIC30B8.gif๋Š” ์ŠคํŠธ๋Ÿฟ B ๋ฐ D์˜ ๊ฒฝ์šฐ๋Š” 0.5์ด๋ฉฐ, ์ŠคํŠธ๋Ÿฟ C์˜ ๊ฒฝ์šฐ๋Š” 0.4์ด๋‹ค. ๋˜ํ•œ ์ŠคํŠธ๋Ÿฟ B, C, D์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜๋ฅผ ์œ„ํ•œ ๊ณ„์ˆ˜ PIC30E8.gif ๋ฐ PIC30F8.gif๋Š” ํœจ์ฒ ๊ทผ ๋น„ PIC3128.gif(=PIC3177.gif, PIC3188.gif), ๊ทธ๋ฆฌ๊ณ  ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ ๋น„ PIC31A8.gif(=PIC31F7.gif, PIC3237.gif), ๊ทธ๋ฆฌ๊ณ  ์ˆ˜์งํ•˜์ค‘์— ๋Œ€ํ•œ ์ˆ˜ํ‰ํ•˜์ค‘์˜ ๋น„ PIC3238.gif(=PIC3268.gif, PIC3288.gif) ๋“ฑ์˜ ์˜ํ–ฅ์„ ๋ฐ˜์˜ํ•˜๊ธฐ ์œ„ํ•œ ๊ฒƒ์œผ๋กœ, ๋‹ค์Œ๊ณผ ๊ฐ™์ด ๊ฒฐ์ •ํ•˜์˜€๋‹ค.

PIC3344.gif (11a)

PIC34FB.gif 

(11b)

PIC36E0.gif 

(11c)

์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๋ณด์ˆ˜์ ์ธ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ์„ค๊ณ„๋ฅผ ์œ„ํ•˜์—ฌ ์ˆ˜์งํ•˜์ค‘์— ๋Œ€ํ•œ ์ˆ˜ํ‰ํ•˜์ค‘์˜ ๋น„ PIC36E1.gif์„ 1.0์œผ๋กœ ์ทจํ•˜๋ฉด, Eq. (11)์˜ ๊ณ„์ˆ˜ PIC3702.gif ๋ฐ PIC3712.gif๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™์ด ๊ฐ„๋žตํ•ด์ง„๋‹ค.

PIC3DDA.gif (12a)

PIC3EC5.gif(12b)

PIC3FD0.gif

(12c)

Eq. (10)์€ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๊ฐ€ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜์ง€ ์•Š๊ณ  ์žˆ๋‹ค. ์ด์— ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๊ฐ€ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•œ Eq. (13)์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC3FFF.gif๋ฅผ Eq. (10)์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC4000.gif์— ๊ณฑํ•˜์—ฌ ์ตœ์ข…์ ์ธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ PIC4021.gif(=PIC4041.gif)๋ฅผ ๊ฒฐ์ •ํ•œ๋‹ค. Eq. (13)์€ Bergmeister ๋“ฑ์ด ์‹คํ—˜์  ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ์ œ์•ˆํ•œ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜๋ฅผ ์ด ์—ฐ๊ตฌ์— ์ ์šฉํ•˜๊ธฐ ์œ„ํ•ด ์ผ๋ถ€ ๋ณ€ํ˜•ํ•œ ๊ฒƒ์ด๋‹ค.

PIC40CF.gif (13)

4. ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ํ•ด์„

๊ธฐ์กด์˜ ์—ฌ๋Ÿฌ ์„ค๊ณ„๊ธฐ์ค€์„œ ๋ฐ ์—ฐ๊ตฌ๋ฌธํ—Œ์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹๊ณผ ์ด ์—ฐ๊ตฌ์—์„œ ์ œ์•ˆํ•œ ์œ ํšจ๊ฐ•๋„ ์‹์˜ ์ ํ•ฉ์„ฑ์„ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ Kriz and Raths (1965), Mattock et al. (1976), and Foster et al. (1996) ๋“ฑ์— ์˜ํ•ด ํŒŒ๊ดด์‹คํ—˜์ด ์ˆ˜ํ–‰๋œ 243๊ฐœ์˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ Fig. 1์˜ ์„ธ ์ข…๋ฅ˜์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•˜์—ฌ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ฐ„๋žตํ•œ ์ œ์› ๋ฐ ์ฃผ์š” ์„ค๊ณ„๋ณ€์ˆ˜์˜ ๋ฒ”์œ„๋Š” Table 1๊ณผ ๊ฐ™์œผ๋ฉฐ, ๊ฐ ์ฝ”๋ฒจ์˜ ์‹คํ—˜์žฅ์น˜, ์ฒ ๊ทผ๋ฐฐ์น˜ ํ˜•ํƒœ, ๊ทธ๋ฆฌ๊ณ  ๊ธฐํƒ€ ์ƒ์„ธํ•œ ์ •๋ณด๋Š” ๊ฐ ์ฐธ๊ณ ๋ฌธํ—Œ์— ์ˆ˜๋ก๋˜์–ด์žˆ๋‹ค.

์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€ ์‹œ ์ ˆ์ ์˜์—ญ์˜ ์œ ํšจ๊ฐ•๋„๊ฐ€ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ํ•ด์„๊ฒฐ๊ณผ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์ตœ์†Œํ™”ํ•˜๊ธฐ ์œ„ํ•ด ๊ตฌ์†๋˜์ง€ ์•Š์€ ๊ทธ๋ฆฌ๊ณ  ์ง€์••ํŒ์— ์˜ํ•ด ํ˜•์„ฑ๋˜๋Š” ์ ˆ์ ์˜์—ญ์—์„œ ์ ํ•ฉํ•œ Bergmeister et al. (1993)์˜ ๊ฐ’์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ๊ทธ๋“ค์ด ์ œ์•ˆํ•œ ์ ˆ์ ์˜์—ญ์˜ ์œ ํšจ๊ฐ•๋„ PIC40EF.gif์€ ๋‹ค์Œ์˜ ์‹๊ณผ ๊ฐ™๋‹ค.

PIC413E.gif (14)

์—ฌ๊ธฐ์„œ, PIC41BC.gif๋Š” ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜๋กœ์„œ PIC41FB.gifMPa, PIC421C.gifPIC424C.gifMPa, PIC427B.gifMPa์˜ ๊ฐ ์กฐ๊ฑด์—์„œ PIC429C.gif, PIC42CC.gifPIC42EC.gif, PIC431C.gif์˜ ๊ฐ’์„ ๊ฐ–๋Š”๋‹ค. ๋˜ํ•œ PIC433C.gif๋Š” ์ง€์••ํŒ์˜ ๋ฉด์ ์„, ๊ทธ๋ฆฌ๊ณ  PIC436C.gif๋Š” ์ง€์••ํŒ๊ณผ ๋„์‹ฌ์ด ๊ฐ™์œผ๋ฉฐ ์ง€์••ํŒ๊ณผ ๋™์ผํ•œ ํ˜•์ƒ์œผ๋กœ ํ™•์žฅํ•œ ๋ฉด์ ์„ ๋‚˜ํƒ€๋‚ด๋ฉฐ, PIC438C.gif์˜ ๊ฐ’์€ 4๋ฅผ ์ดˆ๊ณผํ•  ์ˆ˜ ์—†๋‹ค. ๊ทธ ์™ธ ์ง€์••ํŒ์— ์˜ํ•ด ํ˜•์„ฑ๋˜์ง€ ์•Š๋Š” ์ ˆ์ ์˜์—ญ์˜ ์œ ํšจ๊ฐ•๋„๋กœ๋Š” ๊ทธ๋“ค์˜ ์ œ์•ˆ์— ๋”ฐ๋ผ ๊ณ„์ˆ˜ PIC43AC.gif์— ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„ PIC43DC.gif๋ฅผ ๊ณฑํ•œ ๊ฐ’์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค.

4.1 ์•„์น˜ ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ํ•ด์„

PIC4661.jpg

Fig. 4. Geometrical Shape and Rebar Details of Corbel SA2

PIC4489.jpg

PIC4507.jpg

PIC4585.jpg

(a) Arch Mechanism

(b) Bottle-shaped Mechanism

(c) Combined Mechanism

Fig. 5. Strut-Tie Models for Corbel SA2

Figs. 1(a) and 1(b)์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€๊ณผ์ •์„ ์ „๋‹จ๊ฒฝ๊ฐ„ ๋น„ PIC4691.gif๊ฐ€ 0.34์ธ Fig. 4์˜ ๊ธฐํ•˜ํ•™์  ํ˜•์ƒ ๋ฐ ๋ฐฐ๊ทผ์ƒ์„ธ๋ฅผ ๊ฐ–๋Š” Foster et al. (1996)์˜ ๊ณ ๊ฐ•๋„ ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ SA2๋ฅผ ๋Œ€์ƒ์œผ๋กœ ์†Œ๊ฐœํ•˜์˜€๋‹ค. ์ด ์ฝ”๋ฒจ์˜ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„ PIC46A1.gif๋Š” 87.0MPa์ด๋ฉฐ, ํœจ์ฒ ๊ทผ ๋ฐ ์ˆ˜ํ‰ ์ „๋‹จ์ฒ ๊ทผ์˜ ํ•ญ๋ณต๊ฐ•๋„ PIC46C2.gif๋Š” ๊ฐ๊ฐ 430 ๋ฐ 420MPa์ด๋‹ค. ๋˜ํ•œ ์ด ์ฝ”๋ฒจ์˜ ์žฌํ•˜ํŒ ํญ์€ 100mm์ด๋‹ค.

์ฝ”๋ฒจ SA2์˜ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€๋ฅผ ์œ„ํ•œ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์€ Figs. 5(a) and 5(b)์™€ ๊ฐ™์ด ์„ ์ •ํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ƒ๋ถ€์˜ ์ˆ˜ํ‰ ์ฒ ๊ทผ ํƒ€์ด์˜ ์œ„์น˜๋Š” ํœจ์ฒ ๊ทผ์˜ ๋„์‹ฌ๊ณผ ๊ฐ™๊ฒŒ ํ•˜์˜€์œผ๋ฉฐ, ํ•˜๋ถ€์˜ ์ˆ˜ํ‰ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ„์น˜๋Š” ์ด ์ŠคํŠธ๋Ÿฟ์ด ๋‹จ๋ฉดํญ์ด ๋“ฑ๊ฐ€์‘๋ ฅ๋ธ”๋Ÿญ์˜ ๊นŠ์ด(=PIC46D2.gif, PIC46E3.gif=๋“ฑ๊ฐ€์‘๋ ฅ๋ธ”๋Ÿญ์˜ ๊นŠ์ด์™€ ์ค‘๋ฆฝ์ถ• PIC46F3.gif์™€์˜ ๋น„, PIC4714.gif=์ ˆ์  1์˜ ์œ„์น˜์—์„œ ํœจ์ฒ ๊ทผ์˜ ๋ณ€ํ˜•๋ฅ ์ด ํ•ญ๋ณต๋ณ€ํ˜•๋ฅ ๊ณผ ๊ฐ™์œผ๋ฉฐ ์ ˆ์  2์˜ ์œ„์น˜์—์„œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๋ณ€ํ˜•๋ฅ ์ด 0.003๊ณผ ๊ฐ™๋‹ค๋Š” ๊ฐ€์ • ํ•˜์—์„œ ๊ตฌํ•œ ์ ˆ์  2๋กœ๋ถ€ํ„ฐ ์ค‘๋ฆฝ์ถ•๊นŒ์ง€์˜ ๊ฑฐ๋ฆฌ)์™€ ๊ฐ™๋‹ค๋Š” ๊ฐ€์ • ํ•˜์—์„œ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ํ•˜๋ถ€์˜ ์ˆ˜์ง ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์ˆ˜ํ‰์œ„์น˜๋Š” ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ์— ์ขŒ์šฐ๋œ๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ๋ฅผ ๊ธฐ๋‘ฅ์˜ ์ขŒ์ธก๋ฉด์—์„œ ๊ธฐ๋‘ฅํญ์˜ 25% ๋งŒํผ ๋–จ์–ด์ง„ ๊ณณ ์‚ฌ์ด๋ฅผ 5๋“ฑ๋ถ„ํ•œ ์ ๋“ค๋กœ ์ทจํ•˜์˜€๋‹ค.

์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ์ฝ”๋ฒจ SA2์˜ ๊ทนํ•œ๊ฐ•๋„๋Š” ์ŠคํŠธ๋Ÿฟ, ํƒ€์ด, ๊ทธ๋ฆฌ๊ณ  ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด ๋“ฑ์˜ ์ตœ๋Œ€๋‹จ๋ฉด์ ๊ณผ ํ•„์š”๋‹จ๋ฉด์ ์˜ ํฌ๊ธฐ๋ฅผ ๋น„๊ตํ•˜์—ฌ ๊ฐ ์š”์†Œ์˜ ๊ฐ•๋„๋ฅผ ๊ฒ€ํ† ํ•˜๋Š” ํ˜„ํ–‰ ์ฃผ์š” ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ์„ค๊ณ„๊ธฐ์ค€์˜ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ ๋ฐ ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ์ตœ๋Œ€๋‹จ๋ฉด์ ์€ ์ง€์••ํŒ์˜ ํฌ๊ธฐ ๋ฐ ์ŠคํŠธ๋Ÿฟ๊ณผ ํƒ€์ด์˜ ์œ„์น˜ ๋“ฑ์„ ๊ณ ๋ คํ•˜๋Š” ACI 445 (2002)์˜ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•˜์˜€์œผ๋ฉฐ, ํƒ€์ด์˜ ์ตœ๋Œ€๋‹จ๋ฉด์ ์€ ํƒ€์ด์˜ ์œ„์น˜์— ๋ฐฐ์น˜๋œ ์ฒ ๊ทผ์˜ ๋‹จ๋ฉด์ ์œผ๋กœ ์ทจํ•˜์˜€๋‹ค. Fig. 6์€ ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ๊ฐ€ ๊ธฐ๋‘ฅ์˜ ์ขŒ์ธก๋ฉด์—์„œ ๊ธฐ๋‘ฅํญ์˜ 10%๋งŒํผ ๋–จ์–ด์ง„ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์—์„œ์˜ ์ŠคํŠธ๋Ÿฟ ๋ฐ ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ์ตœ๋Œ€๋‹จ๋ฉดํญ์„ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค. ์ฝ”๋ฒจ์˜ ๋‘๊ป˜ PIC47EF.gif๊ฐ€ ์ผ์ •ํ•˜๋ฏ€๋กœ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ ๋˜๋Š” ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ์ตœ๋Œ€๋‹จ๋ฉด์  PIC483F.gif์€ ๊ทธ ์ตœ๋Œ€๋‹จ๋ฉดํญ PIC488E.gif์— ์ฝ”๋ฒจ์˜ ๋‘๊ป˜ PIC48EC.gif๋ฅผ ๊ณฑํ•˜์—ฌ ์–ป๋Š”๋‹ค. Figs. 6(b) and 6(c)์—์„œ ๋ณผ ์ˆ˜ ์žˆ๋“ฏ์ด, ์ ˆ์ ์˜์—ญ์˜ ํ•œ ๊ฒฝ๊ณ„๋ฉด์— ๋‘ ๊ฐœ ์ด์ƒ์˜ ์ŠคํŠธ๋Ÿฟ์ด ์กด์žฌํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ๊ฒฝ์šฐ ๊ฐ ์ŠคํŠธ๋Ÿฟ์˜ ์ตœ๋Œ€๋‹จ๋ฉด์ ์€ ํ•œ๊ตญ์ฝ˜ํฌ๋ฆฌํŠธํ•™ํšŒ(2013)์˜ ์„ค๊ณ„์˜ˆ์ œ์ง‘์˜ ๋ฐฉ๋ฒ•์— ๋”ฐ๋ผ ๊ตฌํ•˜์˜€๋‹ค. Fig. 6(d)๋Š” Fig. 6(c)์˜ CCT ์ ˆ์ ์˜์—ญ์˜ ํ•œ ๊ฒฝ๊ณ„๋ฉด์— ์ ‘ํ•œ ์„ธ ๊ฐœ ์ŠคํŠธ๋Ÿฟ์˜ ์ตœ๋Œ€๋‹จ๋ฉดํญ ๊ฒฐ์ •๊ณผ์ •์„ ์†Œ๊ฐœํ•œ ๊ฒƒ์ด๋‹ค.

์ŠคํŠธ๋Ÿฟ ๋ฐ ํƒ€์ด ์š”์†Œ์˜ ํ•„์š”๋‹จ๋ฉด์ ์€ ์ด ์ฝ”๋ฒจ์˜ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘ 1,300kN์ด ์ž‘์šฉํ•  ๋•Œ์˜ Fig. 5์— ํ‘œ๊ธฐํ•œ ๊ฐ ์š”์†Œ์˜ ๋‹จ๋ฉด๋ ฅ์„ ํ•ด๋‹น ์š”์†Œ์˜ ์œ ํšจ๊ฐ•๋„๋กœ ๋‚˜๋ˆ„์–ด ๊ตฌํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋Š” 3์žฅ์— ์†Œ๊ฐœํ•œ ๊ฐ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•˜์˜€์œผ๋ฉฐ, ์ฒ ๊ทผ ํƒ€์ด์˜ ์œ ํšจ๊ฐ•๋„๋Š” ์ฒ ๊ทผ์˜ ํ•ญ๋ณต๊ฐ•๋„ PIC4D59.gif๋กœ ์ทจํ•˜์˜€๋‹ค. ์‹คํ—˜ ์‹œ ์ฝ”๋ฒจ์˜ ํŒŒ๊ดดํ•˜์ค‘ PIC4D7A.gif๊ฐ€ ์ฒ ๊ทผ์ด ํ•ญ๋ณตํ•  ๋•Œ์˜ ํ•˜์ค‘ PIC4D8A.gif๋ณด๋‹ค ํฌ๊ฒŒ ๊ฒฐ์ •๋œ ๊ฒฝ์šฐ ์ฒ ๊ทผ ํƒ€์ด์˜ ์œ ํšจ๊ฐ•๋„๋Š” ๋‹ค์Œ์˜ ์‹๊ณผ ๊ฐ™์ด ์ฒ ๊ทผ์˜ ํ•ญ๋ณต๊ฐ•๋„๋ฅผ ์ˆ˜์ •ํ•œ PIC4DBA.gif๋กœ ์ทจํ•˜์˜€๋‹ค.

PIC4A55.jpg

PIC4B40.jpg

PIC4C2C.jpg

(a) Arch Mechanism

(b) Bottle-shaped Mechanism

(c) Combined Mechanism

PIC4CAA.jpg

(d) Provided Strut Widths at Node 1 of Combined Mechanism

Fig. 6. Maximum Provided Widths of Concrete Struts and Nodal Zones in Strut-Tie Models of Corbel SA2

Table 2. Coefficients of Effective Strength of Concrete Strut in Strut-Tie Models for Corbel SA2 PIC4CCA.gif(=PIC4CFA.gif)

Eff. Strength of Strut

EC2

(2004)

FIB

(2010)

AASHTO 

(2010)

ACI 318-11

(2011)

Present      Study

Model &

Strut No.

Arch Mechanism's Model

D

0.39

0.33

0.85

0.64

0.75

Horizontal Truss Mechanism's Model

B

0.39

0.45

0.85

0.64

0.57

C

0.39

0.33

0.73

0.64

0.65

F

0.39

0.33

0.74

0.64

0.81

G

0.39

0.45

0.85

0.64

0.81

PIC4D49.gif=effective strength of strut; Refer to Figs. 1(a) & 1(b) for strut numbers.

Table 3. Evaluation of Ultimate Strength of Corbel SA2 by Determinate Strut-Tie Model of Arch Mechanism

(a) Strength Verification of Strut and Tie

Strut

PIC4DCB.gif

PIC4DEB.gif(MPa)

PIC4DFC.gif(MPa)

PIC4E2C.gif(kN)

PIC4E3C.gif(mm)

PIC4E7C.gif(mm)

PIC4EDA.gif

Safety

D

0.75

87.0

65.4

1412.8

144.1

119.4

0.828

ร—

Tie

PIC4EEB.gif

PIC4F0B.gif(MPa)

PIC5100.gif(MPa)

PIC5298.gif(kN)

PIC52C7.gif(mm2)

PIC5420.gif(mm2)

PIC549E.gif

Safety

A

1.00

430.0

430.0

553.2

1286.4

2027.5

1.576

โ—‹

PIC54CE.gif & PIC54EE.gif: eff. strength coefficients of strut and tie; eff. strength of strut PIC552E.gif; eff. strength of tie PIC555E.gif; PIC557E.gif=cross-sectional force under experimental failure load of 1300kN; PIC55CD.gif; PIC55FD.gif: maximum provided area of strut (Refer to Fig. 8(a))

(b) Strength Verification of Nodal Zone

Node No.

Node Type

PIC562D.gif

PIC563D.gif, PIC565E.gif

(mm2)

PIC566E.gif

PIC567F.gif

(MPa)

PIC5690.gif

(MPa)

PIC56A0.gif

(kN)

PIC56C0.gif

(mm)

PIC56F0.gif

(mm)

PIC574F.gif

Safety

1

CCT 

0.65

100PIC5760.gif150,

340PIC5790.gif150

1.20

87.0

104.3

P

1076.9

68.9

100.0

1.452

โ—‹

Strut D

1170.4

63.1

156.2

2.477

โ—‹

Tie A

458.2

29.3

120.0

4.096

โ—‹

PIC6089.gif(=PIC6250.gif): eff. strength coefficient of nodal zone; eff. strength of nodal zone PIC6260.gif; PIC6290.gif=cross-sectional force under 82.8% of experimental failure load; P=applied load (82.8% of experimental failure load); PIC62C0.gif: maximum provided area of nodal zone boundary (Refer to Fig. 8(a))

Table 4. Ultimate Strengths Evaluated by Determinate Strut-Tie Models of Corbel       PIC62E0.gif

Eff. Strength of Strut

EC2

(2004)

FIB

(2010)

AASHTO

(2010)

ACI 318-11

(2011)

Present Study

Model

& Results

Arch

Mechanism  Model

(243)*

Model (A)

2.71

3.14

1.68

2.64

1.64

Model (B)

1.76

2.03

1.15

1.70

1.15

Model (C)

1.41

1.60

1.00

1.36

1.02

Model (D)

1.32

1.47

0.99

1.27

1.01

Model (E)

1.31

1.43

1.02

1.26

1.04

Total

Average

1.56

1.75

1.10

1.50

1.11

COV(%)

35.2

38.6

26.6

38.9

26.6

Arch

Mechanism  Model

(60)**

Model (A)

2.37

2.75

1.48

1.87

1.41

Model (B)

1.69

1.96

1.13

1.34

1.11

Model (C)

1.41

1.61

1.03

1.14

1.02

Model (D)

1.30

1.47

1.03

1.26

1.04

Model (E)

1.30

1.46

1.09

1.09

1.05

Total

Average

1.51

1.72

1.10

1.23

1.08

COV(%)

34.3

37.2

25.1

32.8

24.2

Horizonal Truss

Mechanism 

Model

(60)**

Model (A)

1.62

1.78

1.88

1.54

1.48

Model (B)

1.47

1.70

1.62

1.25

1.08

Model (C)

1.33

1.51

1.55

1.14

1.08

Model (D)

1.24

1.39

1.58

1.09

1.12

Model (E)

1.21

1.34

1.68

1.10

1.17

Total

Average

1.34

1.51

1.62

1.19

1.15

COV(%)

30.3

33.0

42.2

27.7

17.4

(A)~(E): strut-tie models whose horizontal coordinates of node 2 are located at distances of 5%, 10%, 15%, 20%, and 25%  of column width from the left face of column, respectively; COV: coefficient of variation; *: total number of corbels; **: number of corbels having horizontal shear reinforcing bar(s); Yielding of steel ties describing horizontal shear reinforcing bars is prevented in Bottle-shaped Mechanism Model.

PIC6429.gif (15)

์—ฌ๊ธฐ์„œ, PIC644A.gif ๋ฐ PIC6479.gif๋Š” ํ•ญ๋ณตํ•˜์ค‘ ๋ฐ ํŒŒ๊ดดํ•˜์ค‘์ด ์ž‘์šฉํ•  ๋•Œ์˜ ์ˆ˜ํ‰์ธ์žฅ๋ ฅ์˜ ํฌ๊ธฐ์ด๋ฉฐ, PIC64E8.gif, PIC64F8.gif, PIC6519.gif๋Š” ๊ฐ๊ฐ ์ฝ”๋ฒจ์˜ ๋†’์ด, ์ „๋‹จ์ง€๊ฐ„, ๊ทธ๋ฆฌ๊ณ  ์œ ํšจ๊นŠ์ด์ด๋‹ค. ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ํ•„์š”๋‹จ๋ฉด์ ์€ ์ ˆ์ ์˜์—ญ์— ์—ฐ๊ฒฐ๋œ ์ŠคํŠธ๋Ÿฟ(๋˜๋Š” ํƒ€์ด)์˜ ๋‹จ๋ฉด๋ ฅ์„ ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด ์ˆ˜์ง๋ฐฉํ–ฅ์˜ ๋‹จ๋ฉด๋ ฅ์œผ๋กœ ์น˜ํ™˜ํ•œ ํ›„ ๊ทธ ๋‹จ๋ฉด๋ ฅ์„ Eq. (14)๋กœ๋ถ€ํ„ฐ ๊ฒฐ์ •ํ•œ ์ ˆ์ ์˜์—ญ์˜ ์œ ํšจ๊ฐ•๋„๋กœ ๋‚˜๋ˆ„์–ด ๊ตฌํ•˜์˜€๋‹ค.

Table 2๋Š” Fig. 5์˜ ์•„์น˜ ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ B, C, D์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC6529.gif(=PIC6559.gif)๋ฅผ ์ด ๋…ผ๋ฌธ 3์žฅ์˜ ๊ฐ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•œ ๊ฒƒ์ด๋‹ค. ํ˜„ ์—ฐ๊ตฌ์˜ ๋ฐฉ๋ฒ•์— ์˜ํ•œ ์ŠคํŠธ๋Ÿฟ D์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC656A.gif๋Š” Eq. (11c)๋กœ๋ถ€ํ„ฐ ๊ตฌํ•œ PIC658A.gif(=0.1) ๋ฐ PIC659B.gif(=0.9)์˜ ๊ฐ’์„ Eq. (10)์— ๋Œ€์ž…ํ•˜์—ฌ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜ PIC65BB.gif(=0.88)์„ ๊ตฌํ•œ ํ›„, ์ด๋ฅผ Eq. (13)์˜ PIC65EB.gif(=0.85)์™€ ๊ณฑํ•œ ๊ฒƒ์ด๋‹ค. ๊ณ„์ˆ˜ PIC65FB.gif ๋ฐ PIC660C.gif์˜ ์‚ฐ์ • ์‹œ, ์ฝ”๋ฒจ SA2์— ๋ฐฐ์น˜๋œ ํœจ์ฒ ๊ทผ์€ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘ ์ƒํƒœ์—์„œ ํ•„์š”ํ•œ ์ฒ ๊ทผ๋Ÿ‰ ๋ณด๋‹ค ๋” ๋งŽ์œผ๋ฏ€๋กœ ํœจ์ฒ ๊ทผ ๋น„ PIC663C.gif๋ฅผ 1.0์œผ๋กœ, ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์€ ๋ฐฐ์น˜๋˜์—ˆ์œผ๋‚˜ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์ด ์กด์žฌํ•˜์ง€ ์•Š์•„ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์— ์˜ํ•œ ๊ตฌ์†ํšจ๊ณผ๋ฅผ ๊ณ ๋ คํ•  ์ˆ˜ ์—†์œผ๋ฏ€๋กœ ์ „๋‹จ์ฒ ๊ทผ ๋น„ PIC664D.gif๋ฅผ 0์œผ๋กœ, ๊ทธ๋ฆฌ๊ณ  ์ฝ”๋ฒจ SA2์˜ ์‹คํ—˜ ์‹œ ์ˆ˜ํ‰๋ ฅ์„ ์ž‘์šฉ์‹œํ‚ค์ง€ ์•Š์•˜์œผ๋ฏ€๋กœ PIC666D.gif์„ 0์œผ๋กœ ์ทจํ•˜์˜€๋‹ค. ํ˜„ ์—ฐ๊ตฌ์˜ ๋ฐฉ๋ฒ•์— ์˜ํ•œ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ŠคํŠธ๋Ÿฟ B ๋ฐ C์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜์˜ ๊ฒฐ์ • ์‹œ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ ๋น„ PIC666E.gif๋กœ๋Š” ์‹คํ—˜ ์‹œ ๋ฐฐ์น˜๋œ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ๋Ÿ‰์„ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘์„ ๋ฐ›๋Š” ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ๋กœ๋ถ€ํ„ฐ ๊ฒฐ์ •ํ•œ ํ•„์š” ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ๋Ÿ‰์œผ๋กœ ๋‚˜๋ˆˆ ๊ฐ’์ธ 0.24๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ๊ฐ ๋ฐฉ๋ฒ•์— ์˜ํ•œ ์ŠคํŠธ๋Ÿฟ B ๋ฐ C์˜ ์œ ํšจ๊ฐ•๋„ ๊ฒฐ์ •๊ณผ์ •์— ๋Œ€ํ•œ ์„ค๋ช…์€ ์ƒ๋žตํ•œ๋‹ค.

Table 3์€ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์—ฌ๋Ÿฌ ์œ ํšจ๊ฐ•๋„ ๊ฐ’ ์ค‘ ํ˜„ ์—ฐ๊ตฌ์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ๊ฐ’์„ ์ด์šฉํ•˜์—ฌ ์ฝ”๋ฒจ SA2์˜ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€๊ณผ์ •์„ ์†Œ๊ฐœํ•œ ๊ฒƒ์œผ๋กœ, ์ด ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋Š” ๊ฐ ๊ตฌ์„ฑ์š”์†Œ์˜ ํŒŒ๊ดดํ•˜์ค‘๋น„(=PIC66AD.gif, ์ฝ”๋ฒจ์˜ ๋‘๊ป˜ PIC66BE.gif๊ฐ€ ์ผ์ •ํ•  ๊ฒฝ์šฐ๋Š” PIC672C.gif)์˜ ์ตœ์†Œ๊ฐ’์œผ๋กœ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ์ฝ”๋ฒจ SA2์— ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘์˜ 82.8%์ธ 1076.4kN์ด ์ž‘์šฉํ•  ๋•Œ ์ŠคํŠธ๋Ÿฟ D๊ฐ€ ํŒŒ๊ดด๋˜์—ˆ์œผ๋ฉฐ, ์ด ํ•˜์ค‘ ํ•˜์—์„œ ์ ˆ์ ์˜์—ญ์€ ํŒŒ๊ดด๋˜์ง€ ์•Š์•˜๋‹ค. ๋”ฐ๋ผ์„œ ์ด ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘์˜ 82.8%๋กœ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ๋ชจ๋“  ์ฝ”๋ฒจ ์‹œํ—˜์ฒด์˜ CCC ์ ˆ์ ์˜์—ญ์—์„œ๋Š” ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒ๋˜์ง€ ์•Š์•˜์œผ๋ฏ€๋กœ, ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ด ์ ˆ์ ์˜ ๊ฐ•๋„๋Š” ๊ฒ€ํ† ํ•˜์ง€ ์•Š์•˜๋‹ค. ๋™์ผํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ์„œ๋กœ ๋‹ค๋ฅธ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ๋ฐ ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ๋ฅผ ๊ฐ–๋Š” ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์‚ฌ์šฉํ•˜์—ฌ ๋ชจ๋“  ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ํ‰๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ๋Š” Table 4 and Fig. 9์™€ ๊ฐ™๋‹ค.

243๊ฐœ ๋ฐ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์ด ๋ฐฐ์น˜๋œ 60๊ฐœ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ์•„์น˜ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ๋กœ ํ‰๊ฐ€ํ•œ ๊ฒฐ๊ณผ, ํ˜„ ์—ฐ๊ตฌ ๋ฐ AASHTO (2010)์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์„ ์‚ฌ์šฉํ•  ์‹œ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ํ‰๊ท ์ ์œผ๋กœ ๊ฐ€์žฅ ์–‘ํ˜ธํ•˜๊ฒŒ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ๊ตฌ์„ฑํ•˜๋Š” ์ŠคํŠธ๋Ÿฟ B, C, F, G์˜ ์œ ํšจ๊ฐ•๋„ ์‹์˜ ์ ํ•ฉ์„ฑ์„ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์ด ๋ฐฐ์น˜๋œ 60๊ฐœ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•˜์—ฌ ํ‰๊ฐ€ํ•œ ๊ฒฐ๊ณผ, AASHTO (2010)์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์€ EC2 (2004), FIB (2010), ACI 318-11 (2011)์˜ ์œ ํšจ๊ฐ•๋„ ์‹์— ๋น„ํ•ด ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ๊ฐ€์žฅ ๋ถ€์ •ํ™•ํ•˜๊ฒŒ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๋ฐ˜๋ฉด์— ํ˜„ ์—ฐ๊ตฌ์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์€ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์ด ๋ฐฐ์น˜๋œ 60๊ฐœ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ๊ฐ€์žฅ ์–‘ํ˜ธํ•˜๋ฉฐ ์ผ๊ด€์„ฑ ์žˆ๊ฒŒ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์ด์ƒ์˜ ๊ฒฐ๊ณผ๋Š” ํ˜„ ์—ฐ๊ตฌ์˜ ์•„์น˜ ๋ฉ”์ปค๋‹ˆ์ฆ˜ ๋ชจ๋ธ์˜ ์ŠคํŠธ๋Ÿฟ D ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜ ๋ชจ๋ธ์˜ ์ŠคํŠธ๋Ÿฟ B, C, F, G์˜ ์œ ํšจ๊ฐ•๋„ ์‹์ด ํƒ€๋‹นํ•จ์„ ์ž…์ฆํ•˜๋Š” ๊ฒƒ์ด๋ผ ๋ณผ ์ˆ˜ ์žˆ๋‹ค.

4.2 ๋ณตํ•ฉ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ํ•ด์„

ํ˜„ ์—ฐ๊ตฌ์˜ ์‹์„ ํฌํ•จํ•œ ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์˜ ์—ฌ๋Ÿฌ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์˜ ์ ํ•ฉ์„ฑ์„ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์ด ๋ฐฐ์น˜๋œ 60๊ฐœ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ Fig. 1(c)์˜ ๋ณตํ•ฉ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•˜์—ฌ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€๊ณผ์ •์„ ์†Œ๊ฐœํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์•ž ์ ˆ์—์„œ ์†Œ๊ฐœํ•œ ์ฝ”๋ฒจ SA2๋ฅผ ํƒํ•˜์˜€์œผ๋ฉฐ, ์ด ์ฝ”๋ฒจ์„ ์œ„ํ•œ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์€ Fig. 5(c)์™€ ๊ฐ™๋‹ค. ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ๊ฒฝ์šฐ์™€ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ, ์ƒ๋ถ€์˜ ์ˆ˜ํ‰ ์ฒ ๊ทผ ํƒ€์ด์˜ ์œ„์น˜๋Š” ํœจ์ฒ ๊ทผ์˜ ๋„์‹ฌ๊ณผ ๊ฐ™๊ฒŒ ํ•˜์˜€์œผ๋ฉฐ, ํ•˜๋ถ€์˜ ์ˆ˜ํ‰ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ„์น˜๋Š” ๋“ฑ๊ฐ€์‘๋ ฅ๋ธ”๋Ÿญ์˜ ๊นŠ์ด๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ํ•˜๋ถ€์˜ ์ˆ˜์ง ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ„์น˜๋Š” ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ์— ์ขŒ์šฐ๋˜๋ฏ€๋กœ, ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ๋ฅผ ๊ธฐ๋‘ฅ์˜ ์ขŒ์ธก๋ฉด์—์„œ ๊ธฐ๋‘ฅํญ์˜ 25% ๋งŒํผ ๋–จ์–ด์ง„ ๊ณณ ์‚ฌ์ด๋ฅผ 5๋“ฑ๋ถ„ํ•œ ์ ๋“ค๋กœ ์ทจํ•˜์˜€๋‹ค.

์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ์ฝ”๋ฒจ SA2์˜ ๊ทนํ•œ๊ฐ•๋„๋Š” 4.1์ ˆ์—์„œ ์†Œ๊ฐœํ•œ ๋ฐ”์™€ ๊ฐ™์ด ์ŠคํŠธ๋Ÿฟ, ํƒ€์ด, ๊ทธ๋ฆฌ๊ณ  ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด ๋“ฑ์˜ ์ตœ๋Œ€๋‹จ๋ฉด์ ๊ณผ ํ•„์š”๋‹จ๋ฉด์ ์˜ ํฌ๊ธฐ๋ฅผ ๋น„๊ตํ•˜์—ฌ ๊ฐ ์š”์†Œ์˜ ๊ฐ•๋„๋ฅผ ๊ฒ€ํ† ํ•˜๋Š” ํ˜„ํ–‰ ์ฃผ์š” ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ์„ค๊ณ„๊ธฐ์ค€์˜ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ, ํƒ€์ด, ๊ทธ๋ฆฌ๊ณ  ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ์ตœ๋Œ€๋‹จ๋ฉด์ ์€ 4.1์ ˆ์—์„œ ์†Œ๊ฐœํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. Fig. 6(c)๋Š” ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ๊ฐ€ ๊ธฐ๋‘ฅ์˜ ์ขŒ์ธก๋ฉด์—์„œ ๊ธฐ๋‘ฅํญ์˜ 10%๋งŒํผ ๋–จ์–ด์ง„ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์—์„œ์˜ ์ŠคํŠธ๋Ÿฟ ๋ฐ ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ์ตœ๋Œ€๋‹จ๋ฉดํญ์„ ๋ณด์ธ ๊ฒƒ์ด๋‹ค. ์ŠคํŠธ๋Ÿฟ ๋ฐ ํƒ€์ด ์š”์†Œ์˜ ํ•„์š”๋‹จ๋ฉด์ ์€ ์ด ์ฝ”๋ฒจ์˜ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘ 1,300kN์ด ์ž‘์šฉํ•  ๋•Œ์˜ Fig. 5(c)์— ํ‘œ๊ธฐํ•œ ๊ฐ ์š”์†Œ์˜ ๋‹จ๋ฉด๋ ฅ์„ ํ•ด๋‹น ์š”์†Œ์˜ ์œ ํšจ๊ฐ•๋„๋กœ ๋‚˜๋ˆ„์–ด ๊ตฌํ•˜์˜€๋‹ค. ์ด๋•Œ ์ŠคํŠธ๋Ÿฟ๊ณผ ํƒ€์ด์˜ ๋‹จ๋ฉด๋ ฅ์€ Eq. (1)์˜ ํ•˜์ค‘๋ถ„๋ฐฐ์œจ ๋ฐ ํŠธ๋Ÿฌ์Šค ๊ตฌ์กฐ์˜ ์ ˆ์ ํ•ด์„๋ฒ•์„ ์ ์šฉํ•˜์—ฌ ๊ตฌํ•˜์˜€๋‹ค. ์ฆ‰ ์ž‘์šฉํ•˜์ค‘๊ณผ ์ˆ˜ํ‰ํƒ€์ด์˜ ๋‹จ๋ฉด๋ ฅ ๋น„๋กœ ์ •์˜ํ•œ ๋‹ค์Œ์˜ ํ•˜์ค‘๋ถ„๋ฐฐ์œจ PIC679B.gif(%)๋กœ๋ถ€ํ„ฐ ํƒ€์ด E์˜ ๋‹จ๋ฉด๋ ฅ์„ ๊ตฌํ•œ ํ›„, ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๊ฐ ์ ˆ์ ์—์„œ์˜ ํ‰ํ˜•์กฐ๊ฑด์„ ์ ์šฉ์‹œ์ผœ ๋ชจ๋“  ์ŠคํŠธ๋Ÿฟ๊ณผ ํƒ€์ด์˜ ๋‹จ๋ฉด๋ ฅ์„ ๊ฒฐ์ •ํ•˜์˜€๋‹ค.

PIC6809.jpg

(a) EC 2's Effective Strength of Strut

PIC6839.jpg

(b) FIB's Effective Strength of Strut

PIC68D6.jpg

(c) AASHTO's Effective Strength of Strut

PIC6964.jpg

(d) ACI 318's Effective Strength of Strut

PIC6984.jpg

(e) Present Study

Fig. 7. Ultimate Strengths Evaluated by Determinate and Indeterminate Strut-Tie Models of Corbel

PIC6A21.gif

์—ฌ๊ธฐ์„œ, ํ•˜์ค‘๋ถ„๋ฐฐ์œจ์˜ ๋ณ€ํ™”๋ฅผ ๊ณ ๋ คํ•˜๋Š” ๋ณ€์ˆ˜ PIC6A32.gif, PIC6A43.gif, PIC6A53.gif์˜ ๊ฐ’์€ PIC6A83.gif=87.0, PIC6AD2.gif=2.26, PIC6AE3.gif=0.0์„ ์‚ฌ์šฉํ•˜์—ฌ Eq. (2)๋กœ๋ถ€ํ„ฐ ๊ตฌํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„, ์ฒ ๊ทผ ํƒ€์ด์˜ ์œ ํšจ๊ฐ•๋„, ๊ทธ๋ฆฌ๊ณ  ์ ˆ์ ์˜์—ญ ๊ฒฝ๊ณ„๋ฉด์˜ ํ•„์š”๋‹จ๋ฉด์ ์€ 4.1์ ˆ์—์„œ ์†Œ๊ฐœํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ์ด ๋…ผ๋ฌธ์˜ 3์žฅ์˜ ๊ฐ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•œ Fig. 5(c)์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๊ณ„์ˆ˜๋Š” Table 2์˜ ๊ฐ’๊ณผ ๋™์ผํ•˜๋‹ค.

Table 5. Evaluation of Ultimate Strength of Corbel SA2 by Indeterminate Strut-Tie Model of Combined Mechanism

(a) Strength Verification of Struts and Ties at First Failure

Strut

PIC6B03.gif

PIC6B23.gif(MPa)

PIC6B34.gif(MPa)

PIC6B64.gif(kN)

PIC6B74.gif(mm)

PIC6B95.gif(mm)

PIC6BD4.gif

Safety

B

0.57

87.0

49.3

371.6

50.2

46.2

0.919

ร—

C

0.65

87.0

56.9

488.0

57.2

60.6

1.061

โ—‹

D

0.77

87.0

67.1

605.0

60.1

72.0

1.198

โ—‹

F

0.81

87.0

70.3

488.0

46.3

58.1

1.254

โ—‹

G

0.81

87.0

70.3

371.6

35.3

44.2

1.254

โ—‹

Tie

PIC6C04.gif

PIC6C24.gif(MPa)

PIC6C25.gif(MPa)

PIC6C46.gif(kN)

PIC6C66.gif(mm2)

PIC6CB5.gif(mm2)

PIC6D04.gif

Safety

A

1.00

430.0

430.0

553.2

1286.4

2027.5

1.576

โ—‹

E

1.00

420.0

420.0

316.3

753.0

315.6

0.419

ร—

PIC6D24.gif & PIC6D35.gif: eff. strength coefficients of strut and tie; eff. strength of strut PIC6D46.gif; eff. strength of tie PIC6D56.gif; PIC6D76.gif=cross-sectional force under experimental failure load of 1300kN; PIC6DA6.gif; PIC6DD6.gif: maximum provided area of strut (Refer to Fig. 8(c))

(b) Strength Verification of Strut and Tie at Second Failure

Strut

PIC6DE7.gif

PIC6DF7.gif(MPa)

PIC6E18.gif(MPa)

PIC6E38.gif(kN)

PIC6E58.gif(mm)

PIC6E98.gif(mm)

PIC6EF6.gif

Safety

D

0.77

87.0

67.1

1412.8

140.3

78.7

0.561

ร—

Tie

PIC6F07.gif

PIC6F18.gif(MPa)

PIC6F48.gif(MPa)

PIC6F68.gif(kN)

PIC6F88.gif(mm2)

PIC6FA8.gif(mm2)

PIC6FE8.gif

Safety

A

1.00

430.0

430.0

553.2

1286.4

1488.4

1.157

โ—‹

PIC7008.gif=cross-sectional force under experimental failure load of 1300kN; PIC7038.gif: maximum provided area of strut after first failure (Refer to Fig. 10(b))

(c) Strength Verification of Nodal Zone

Node No.

Node Type

PIC7049.gif

PIC7059.gif, PIC706A.gif

(mm2)

PIC707A.gif

PIC708B.gif

(MPa)

PIC709C.gif

(MPa)

PIC70DB.gif

(kN)

PIC70FB.gif

(mm)

PIC711C.gif

(mm)

PIC715B.gif

Safety

1

CCT 

0.65

100PIC716C.gif150,

340PIC717C.gif150

1.20

87.0

104.3

P

1273.8

81.4

100.0

1.228

โ—‹

Strut B

155.8

74.6

156.2

2.094

โ—‹

Strut C

204.5

Strut D

1045.8

Tie A

542.0

34.7

120.0

3.463

โ—‹

PIC71CC.gif(=PIC720B.gif): eff. strength coefficient of nodal zone; eff. strength of nodal zone PIC721C.gif; PIC723C.gif=cross-sectional force under 97.9% of experimental failure load; P=applied load (97.9% of experimental failure load); PIC72F8.gif: maximum provided area of nodal zone boundary (Refer to Fig. 10(e))

์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์—ฌ๋Ÿฌ ์œ ํšจ๊ฐ•๋„ ๊ฐ’ ์ค‘ ํ˜„ ์—ฐ๊ตฌ์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ๊ฐ’์„ ์ด์šฉํ•˜์—ฌ ์ฝ”๋ฒจ SA2์˜ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€๊ณผ์ •์€ Table 5์— ์ƒ์„ธํžˆ ์†Œ๊ฐœํ•˜์˜€๋‹ค. ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•œ ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€ ์‹œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ํ•˜์ค‘์ „๋‹ฌ ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ๊ตฌ์„ฑํ•˜๋Š” ํ•˜๋‚˜์˜ ์š”์†Œ๊ฐ€ ์ผ์ฐจ์ ์œผ๋กœ ํŒŒ๊ดด๋˜์–ด๋„ ๋‹ค๋ฅธ ์š”์†Œ๋“ค๋กœ ๊ตฌ์„ฑ๋œ ๋‹ค๋ฅธ ํ•˜์ค‘์ „๋‹ฌ ๋ฉ”์ปค๋‹ˆ์ฆ˜์— ์˜ํ•ด ์ถ”๊ฐ€์ ์ธ ํ•˜์ค‘์ด ์ „๋‹ฌ๋˜๋Š” ๊ฒƒ์œผ๋กœ ๋ณด์•˜๋‹ค. Table 5(a)์— ๋‚˜ํƒ€๋‚œ ๊ฒƒ๊ณผ ๊ฐ™์ด, ์ฝ”๋ฒจ SA2 ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ 1์ฐจ ํŒŒ๊ดด๋Š” ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ๊ตฌ์„ฑํ•˜๋Š” ์ˆ˜ํ‰ ํƒ€์ด E๊ฐ€ ์ตœ๋Œ€๋กœ ๋ฐ›์„ ์ˆ˜ ์žˆ๋Š” ํ•˜์ค‘, ์ฆ‰ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘์˜ 41.9%์ธ 544.8kN์—์„œ ๋ฐœ์ƒํ•˜์˜€๋‹ค. 1์ฐจ ํŒŒ๊ดด ํ›„ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์€ ์—ฌ๋ถ„์˜ ๋‹จ๋ฉด์ ์„ ๊ฐ€์ง€๊ณ  ์žˆ๋Š” ์ƒ๋ถ€ ์ˆ˜ํ‰ ํƒ€์ด A ๋ฐ ๊ฒฝ์‚ฌ ์ŠคํŠธ๋Ÿฟ D์— ์˜ํ•œ ์•„์น˜ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ๋กœ ๋ณ€ํ™˜๋˜์–ด ์ถ”๊ฐ€์ ์ธ ํ•˜์ค‘์„ ์ง€์ ์œผ๋กœ ์ „๋‹ฌํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” 1์ฐจ ํŒŒ๊ดด ํ›„ 1๋ฒˆ ์ ˆ์ ์˜์—ญ์˜ ํ•œ ๊ฒฝ๊ณ„๋ฉด์„ ๊ณต์œ ํ•˜๊ณ  ์žˆ๋Š” ์ŠคํŠธ๋Ÿฟ B ๋ฐ C์˜ ์—ฌ์œ ๋‹จ๋ฉด์ ์„ ์ŠคํŠธ๋Ÿฟ D ๋ฐฉํ–ฅ์˜ ๋‹จ๋ฉด์ ์œผ๋กœ ์น˜ํ™˜ํ•˜์—ฌ ์ŠคํŠธ๋Ÿฟ D์˜ ์—ฌ์œ ๋‹จ๋ฉด์ ์— ์ถ”๊ฐ€ํ•˜์˜€๋‹ค. ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ 2์ฐจ ํŒŒ๊ดด๋Š” Table 5(b)์— ๋‚˜ํƒ€๋‚œ ๊ฒƒ๊ณผ ๊ฐ™์ด ์ŠคํŠธ๋Ÿฟ D๊ฐ€ ์ตœ๋Œ€๋กœ ๋ฐ›์„ ์ˆ˜ ์žˆ๋Š” ํ•˜์ค‘, ์ฆ‰ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘์˜ 56.1%์ธ 729.0kN์—์„œ ๋ฐœ์ƒํ•˜์˜€๋‹ค. 2์ฐจ ํŒŒ๊ดด ํ›„ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์€ ๋ถˆ์•ˆ์ •ํ•œ ํŠธ๋Ÿฌ์Šค ๊ตฌ์กฐ๊ฐ€ ๋˜์–ด ๋” ์ด์ƒ์˜ ํ•˜์ค‘์„ ์ง€์ ์œผ๋กœ ์ „๋‹ฌํ•  ์ˆ˜ ์—†๋‹ค. ์ด ์ƒํƒœ ํ•˜์—์„œ, ์ฆ‰ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์ด ๋ฐ›์„ ์ˆ˜ ์žˆ๋Š” ์ตœ๋Œ€ํ•˜์ค‘ 1273.8kN (=544.8+729.0)ํ•˜์—์„œ ์ ˆ์ ์˜์—ญ์˜ ๊ฐ•๋„๋ฅผ ๊ฒ€ํ† ํ•˜์˜€๋‹ค. Table 5(c)์— ๋‚˜ํƒ€๋‚œ ๊ฒƒ๊ณผ ๊ฐ™์ด ์ตœ๋Œ€ํ•˜์ค‘ 1273.8kNํ•˜์—์„œ ๋ชจ๋“  ์ ˆ์  1์˜ CCT ์ ˆ์ ์˜์—ญ์€ ๊ฐ•๋„์— ์•„๋ฌด๋Ÿฐ ๋ฌธ์ œ๊ฐ€ ์—†์—ˆ๋‹ค. ๋”ฐ๋ผ์„œ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์— ์˜ํ•œ ์ฝ”๋ฒจ SA2์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ 1273.8kN, ์ฆ‰ ์‹คํ—˜ํŒŒ๊ดดํ•˜์ค‘์˜ 97.9%๋กœ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์‹คํ—˜ ์‹œ ๋ชจ๋“  ์ฝ”๋ฒจ์˜ ์ ˆ์  2์˜ CCC ์ ˆ์ ์˜์—ญ๊ณผ ์ ˆ์  3 ๋ฐ 4์˜ CCT ์ ˆ์ ์˜์—ญ์—์„œ๋Š” ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒ๋˜์ง€ ์•Š์•˜์œผ๋ฏ€๋กœ, ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ด๋“ค ์ ˆ์ ์˜์—ญ์˜ ๊ฐ•๋„๋Š” ๊ฒ€ํ† ํ•˜์ง€ ์•Š์•˜๋‹ค. ๋™์ผํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ์„œ๋กœ ๋‹ค๋ฅธ ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ๋ฐ ์ ˆ์  2์˜ ์ˆ˜ํ‰์ขŒํ‘œ๋ฅผ ๊ฐ–๋Š” ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์‚ฌ์šฉํ•˜์—ฌ ๋ชจ๋“  ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ํ‰๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ๋Š” Table 6 and Fig. 7๊ณผ ๊ฐ™๋‹ค.

์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ์ด ๋ฐฐ์น˜๋œ 60๊ฐœ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ๋ณตํ•ฉ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ๋กœ ํ‰๊ฐ€ํ•œ ๊ฒฐ๊ณผ, ํ˜„ ์—ฐ๊ตฌ ๋ฐ AASHTO (2010)์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์„ ์‚ฌ์šฉํ•  ์‹œ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ํ‰๊ท ์ ์œผ๋กœ ๊ฐ€์žฅ ์–‘ํ˜ธํ•˜๊ฒŒ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๋˜ํ•œ Tables 4 and 6์— ๋‚˜ํƒ€๋‚œ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•ด๋ณผ ๋•Œ ์•„์น˜ ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์กฐํ•ฉํ•œ ๋ณตํ•ฉ ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์€ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์— ๋น„ํ•ด ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ฐ•๋„๋ฅผ ์ „์ฒด์ ์œผ๋กœ ๋” ์ž˜ ํ‰๊ฐ€ํ•จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ์ด๋Š” ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์— ์˜ํ•œ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ํ•ด์„ ๋ฐ ์„ค๊ณ„ ๊ฒฐ๊ณผ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋ฟ ์•„๋‹ˆ๋ผ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์˜ ํ˜•ํƒœ์— ๋”ฐ๋ผ ๋‹ฌ๋ผ์งˆ ์ˆ˜ ์žˆ์Œ์„ ์˜๋ฏธํ•œ๋‹ค.

Table 6. Ultimate Strengths Evaluated by Corbelโ€™s Indeterminate Strut-Tie Model of Combined Mechanism    PIC7328.gif

Eff. Strength of Strut

EC2

(2004)

FIB

(2010)

AASHTO (2010)

ACI 318-11

(2011)

Present Study

Model

& Results

Combined

Mechanism  Model

(60)*

Model (A)

1.52

1.73

1.17

1.27

1.03

Model (B)

1.48

1.74

1.11

1.22

1.00

Model (C)

1.33

1.50

1.06

1.11

0.98

Model (D)

1.24

1.37

1.06

1.06

0.99

Model (E)

1.21

1.32

1.10

1.06

1.04

Total

Average

1.33

1.49

1.09

1.12

1.00

COV(%)

29.6

33.5

21.1

27.9

18.2

(A)~(E): (A)~(E): strut-tie models whose horizontal coordinates of node 2 are located at distances of 5%, 10%, 15%, 20%, and 25%  of column width from the left face of column, respectively; *: number of corbels having horizontal shear reinforcing bar(s)

5. ์š”์•ฝ ๋ฐ ๊ฒฐ๋ก 

์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ๋ฐฉ๋ฒ•์„ ์ด์šฉํ•˜์—ฌ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์„ ์•ˆ์ „ํ•˜๊ณ  ๊ฒฝ์ œ์ ์œผ๋กœ ์„ค๊ณ„ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„๋ฅผ ์ •ํ™•ํ•˜๊ฒŒ ๊ฒฐ์ •ํ•˜์—ฌ์•ผ ํ•œ๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ ์„ค๊ณ„๋ฅผ ์œ„ํ•˜์—ฌ ์ „๋‹จ๊ฒฝ๊ฐ„๋น„, ํœจ์ฒ ๊ทผ๋น„, ์ˆ˜ํ‰์ „๋‹จ์ฒ ๊ทผ๋น„, ๊ทธ๋ฆฌ๊ณ  ์ˆ˜์งํ•˜์ค‘์— ๋Œ€ํ•œ ์ˆ˜ํ‰ํ•˜์ค‘์˜ ๋น„ ๋“ฑ์˜ ์ฃผ์š” ์„ค๊ณ„๋ณ€์ˆ˜๋“ค์˜ ์˜ํ–ฅ์„ ํ•ฉ๋ฆฌ์ ์œผ๋กœ ๋ฐ˜์˜ํ•  ์ˆ˜ ์žˆ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์„ ๊ฐœ๋ฐœ, ์ œ์•ˆํ•˜์˜€๋‹ค. ์ œ์•ˆํ•œ ์œ ํšจ๊ฐ•๋„ ์‹์˜ ์ ํ•ฉ์„ฑ์„ ๊ฒ€์ฆํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ํŒŒ๊ดด์‹คํ—˜์ด ์ˆ˜ํ–‰๋œ 243๊ฐœ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ์•„์น˜ ๋ฐ ์ˆ˜ํ‰ ํŠธ๋Ÿฌ์Šค ๋ฉ”์ปค๋‹ˆ์ฆ˜์˜ ์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ๊ณผ ๋‘ ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์กฐํ•ฉํ•œ ๋ถ€์ •์ • ์ŠคํŠธ๋Ÿฟ-ํƒ€์ด ๋ชจ๋ธ์„ ์ด์šฉํ•˜์—ฌ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๊ทนํ•œ๊ฐ•๋„ ํ‰๊ฐ€๊ฒฐ๊ณผ, ์ด ์—ฐ๊ตฌ์—์„œ ์ œ์‹œํ•œ ์ŠคํŠธ๋Ÿฟ์˜ ์œ ํšจ๊ฐ•๋„ ์‹์ด ํ˜„ํ–‰ ์—ฌ๋Ÿฌ ์„ค๊ณ„๊ธฐ์ค€์„œ์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹๋“ค์— ๋น„ํ•ด ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ์ฝ”๋ฒจ์˜ ๊ทนํ•œ๊ฐ•๋„๋ฅผ ๊ฐ€์žฅ ์ •ํ™•ํ•˜๊ณ  ์ผ๊ด€์„ฑ ์žˆ๊ฒŒ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์ด ์—ฐ๊ตฌ์˜ ์ŠคํŠธ๋Ÿฟ ์œ ํšจ๊ฐ•๋„ ์‹์€ ์ „๋‹จ๊ฒฝ๊ฐ„๋น„๊ฐ€ 1.0 ์ดํ•˜์ธ ์ฝ”๋ฒจ์˜ ์„ค๊ณ„ ์‹œ๋งŒ ์ ์šฉํ•  ์ˆ˜ ์žˆ๋Š” ๊ฒƒ์œผ๋กœ, ํ˜„ํ–‰ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ์„ค๊ณ„๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ์ „๋‹จ๊ฒฝ๊ฐ„๋น„๊ฐ€ 2.0 ๋ฏธ๋งŒ์ธ ์ฝ”๋ฒจ์˜ ์„ค๊ณ„๋ฅผ ์œ„ํ•œ ์ถ”๊ฐ€์ ์ธ ์—ฐ๊ตฌ๊ฐ€ ํ•„์š”ํ•˜๋‹ค.

Acknowledgements

๋ณธ ์—ฐ๊ตฌ๋Š” ๊ตญํ† ๊ตํ†ต๋ถ€๊ฐ€ ์ฃผ๊ด€ํ•˜๊ณ  ๊ตญํ† ๊ตํ†ต๊ณผํ•™๊ธฐ์ˆ ์ง„ํฅ์›์ด ์‹œํ–‰ํ•˜๋Š” 2012๋…„๋„ ๊ฑด์„ค๊ตํ†ต๊ธฐ์ˆ  ์ง€์—ญํŠน์„ฑํ™”์‚ฌ์—…(12 ์ง€์—ญ๊ธฐ์ˆ ํ˜์‹  B01)์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰๋œ ์—ฐ๊ตฌ์ž„.

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