new suggestion of effective moment of inertia for beams

7

Upload: others

Post on 20-Jan-2022

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: New Suggestion of Effective Moment of Inertia for Beams

185

Journal of the Korea Concrete Institute

Vol. 20, No. 2, pp. 185~191, April, 2008

์ดํ˜• GFRP Rebar๋กœ ๋ณด๊ฐ•๋œ ๋ณด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹ ์ œ์•ˆ

์‹ฌ์ข…์„ฑ1)ยท์˜คํ™์„ญ

2)ยท์ฃผ๋ฏผ๊ด€

1)*ยท์ž„์ค€ํ˜„

3)

1)ํ•œ์–‘๋Œ€ํ•™๊ต ํ† ๋ชฉ๊ณตํ•™๊ณผ

2)์ง„์ฃผ์‚ฐ์—…๋Œ€ํ•™๊ต ํ† ๋ชฉ๊ณตํ•™๊ณผ

3)(์ฃผ)์‚ผ๋ณด๊ธฐ์ˆ ๋‹จ

New Suggestion of Effective Moment of Inertia for Beams Reinforced with

the Deformed GFRP Rebar

Jong-Sung Sim1)*

, Hong-Seob Oh2), Min-Kwan Ju

1)*, and Jun-Hyun Lim3)

1)Dept. of Civil Engineering, Hanyang University, Ansan 426-791, Korea

2)Dept. of Civil Engineering, Jinju National University, Jinju 660-758, Korea

3)Sambo Engineering Co., Ltd., Seoul 138-834, Korea

ABSTRACT To fundamentally solve the problem of deterioration of concrete structures, it has been researched that the high

durable concrete structure reinforced with the FRP rebar can be one of major solution to the newly-developed concrete structure.

FRP rebar has lots of advantages such as non-corrosive, high performance and light weight against the conventional steel rebar.

Among these kinds of FRP rebars, GFRP rebar has usually been considered as the best reinforcement because of its economic point

of view. Even though the material capacity of the GFRP rebar was already investigated, there are some problems such as low mod-

ulus of elastic that will be cause for degrade of the serviceability of flexural concrete member reinforced with the GFRP rebar.

Thus, the deflection characteristics of the GFRP rebar reinforced concrete structure should be considered then investigated. In this

study, ACI 440 guideline (2003), ISIS Canada Design Manual (2001) and Toutanji et al. (2000) was considered for predicting the

moment of inertia of the concrete beam reinforced with the GFRP rebar. And it was also evaluated that load-deflection relationship

had a good accordance with the test and analysis result. In the result of this study, it could be estimated that the load-deflection

relationship using the suggested equation of moment of inertia in this study indicated better accordance with the test result than

that of the others until failure.

Keywords : deformed GFRP rebar, durability, effective moment of inertia, serviceability

1. ์„œ ๋ก 

์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์—์„œ์˜ ์ฒ ๊ทผ์˜ ๋ถ€์‹์€ ๊ตฌ์กฐ ์„ฑ๋Šฅ ๋ฐ ๋‚ด

๊ตฌ ์„ฑ๋Šฅ์„ ์ €ํ•˜์‹œํ‚ค๋Š” ์ฃผ์š”ํ•œ ์š”์ธ์ด๋ฉฐ ๋ณด์ˆ˜, ๋ณด๊ฐ• ๋“ฑ

์œ ์ง€๊ด€๋ฆฌ์ƒ์˜ ๋ฌธ์ œ๋ฅผ ๋ฐœ์ƒ์‹œํ‚ค๋Š” ์ฃผ์š” ์ธ์ž์ด๋‹ค. ์ด์ฐฝ์ˆ˜

๋“ฑ์— ์˜ํ•˜๋ฉด ์„œ์šธ์‹œ์˜ ๋Œ€ํ‘œ์ ์ธ ๊ตฌ์กฐ๋ฌผ 140๊ฐœ๋ฅผ ์กฐ์‚ฌํ•œ

๊ฒฐ๊ณผ, 418๊ฐœ์†Œ์—์„œ ์—ดํ™” ์ƒํƒœ๊ฐ€ ๋ณด๊ณ ๋˜์—ˆ์œผ๋ฉฐ, ์ฒ ๊ทผ๋ถ€์‹

์œผ๋กœ ์ธํ•ด ๋ณด์ˆ˜ ๋ฐ ๋ณด๊ฐ•์„ ์š”ํ•˜๋Š” ๊ณณ์ด 46๊ฐœ์†Œ (11%)์ธ

๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๋˜ํ•œ ๋ฏธ๊ตญ์˜ ๊ฒฝ์šฐ ์ด 580,000๊ฐœ์˜ ๊ต

๋Ÿ‰์— ๊ฒฐํ•จ์ด ๋ฐœ๊ฒฌ๋˜์–ด ์ฆ‰์‹œ ๋ณด์ˆ˜๋ณด๊ฐ•์ด ํ•„์š”ํ•˜๋ฉฐ ์ด๊ฒƒ์€

์ „์ฒด ๊ต๋Ÿ‰ ๊ตฌ์กฐ๋ฌผ์˜ ์•ฝ 31% ์ •๋„๊ฐ€ ์ฒ ๊ทผ๋ถ€์‹์— ์˜ํ•œ ๋…ธ

ํ›„ํ™”๊ฐ€ ์ง„ํ–‰๋œ ๊ฒƒ์œผ๋กœ ๋ณด๊ณ ๋˜์—ˆ๋‹ค. ํ˜„์žฌ ๋ฏธ์—ฐ๋ฐฉ๋„๋กœ๊ตญ์—

์„œ๋Š” ์—ฐ๊ฐ„ ๊ต๋Ÿ‰ ๊ตฌ์กฐ๋ฌผ์˜ ๋ณด์ˆ˜์— ์•ฝ 2์–ต ๋‹ฌ๋Ÿฌ์˜ ์˜ˆ์‚ฐ์„

์†Œ์š”ํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ๊ณ ์†๋„๋กœ ๋ฐ ๊ณ ์†๋„๋กœ๊ต๋Ÿ‰์˜ ์œ ์ง€๊ด€๋ฆฌ

๋ฐ ๋ณด์ˆ˜๋ฅผ ์œ„ํ•ด ๋งค๋…„ 3์–ต 1์ฒœ๋งŒ ๋‹ฌ๋Ÿฌ๋ฅผ ์‚ฌ์šฉํ•˜๊ณ  ์žˆ๋‹ค2).

์ตœ๊ทผ ์ด์™€ ๊ฐ™์€ ์ฝ˜ํฌ๋ฆฌํŠธ ์—ดํ™”์™€ ๊ฐ™์€ ๋ฌธ์ œ๋ฅผ ๊ทผ๋ณธ์ 

์œผ๋กœ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•ด ๊ณ ๋‚ด๊ตฌ์„ฑ์„ ๋ณด์œ ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ

์˜ ์žฅ์ˆ˜๋ช…ํ™”์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ํ™œ๋ฐœํžˆ ์ง„ํ–‰๋˜๊ณ  ์žˆ๋Š” ๊ฐ€์šด

๋ฐ ๊ธฐ์กด์˜ ์ฒ ๊ทผ ๋ณด๊ฐ•์žฌ๋ณด๋‹ค ๊ฐ€๋ณ๊ณ  ๊ณ ๊ฐ•๋„ ๋ฐ ๊ณ ๋‚ด๊ตฌ์„ฑ

์„ ๋ณด์œ ํ•œ ๊ฑด์„ค ์‹ ์†Œ์žฌ์— ๋Œ€ํ•œ ์—ฐ๊ตฌยท๊ฐœ๋ฐœ ๋ฐ ํ™œ์šฉ์ด ์ 

์ฐจ ์ฆ๊ฐ€๋˜๋Š” ์ถ”์„ธ์ด๋‹ค. ๋Œ€ํ‘œ์ ์ธ ๊ฑด์„ค ๋ณตํ•ฉ ์‹ ์†Œ์žฌ์ธ

CFRP, GFRP ๋ฐ AFRP rebar์˜ ๊ฒฝ์šฐ, ์ด๋ฏธ ๊ตญ๋‚ด์™ธ์ ์œผ๋กœ

ํ™œ๋ฐœํ•œ ์—ฐ๊ตฌ๊ฐœ๋ฐœ์ด ์ด๋ฃจ์–ด์ง€๊ณ  ์žˆ๋Š” ์‹ค์ •์ด๋‹ค. ํ•˜์ง€๋งŒ ํ˜„

์žฌ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์—์˜ ๊ฒฝ์ œ์ ์ธ ์ธก๋ฉด์—์„œ ์ ์šฉ ๊ฐ€๋Šฅํ•œ

FRP rebar๋กœ์„œ๋Š” GFRP rebar๊ฐ€ ์ฃผ๋ชฉ์„ ๋ฐ›๊ณ  ์žˆ์œผ๋ฉฐ ๊ทธ

์‚ฌ์šฉ์„ฑ ๋˜ํ•œ ์ฆ๋Œ€๋˜๊ณ  ์žˆ๋Š” ์ถ”์„ธ์ด๋‹ค.

ํ˜„์žฌ GFRP rebar๋ฅผ ํ™œ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์˜ ์„ค๊ณ„๋Š”

๋ฏธ๊ตญ ACI 440 ์œ„์›ํšŒ์—์„œ ์ง€์†์ ์œผ๋กœ ์—ฐ๊ตฌ ์ค‘์ธ ์„ค๊ณ„์ง€

์นจ์ด ์ด๋ฏธ ๊ฐœ๋ฐœ๋˜์–ด ์žˆ์ง€๋งŒ, GFRP rebar์˜ ๊ฒฝ์šฐ, ๊ธฐ์กด

์ฒ ๊ทผ๋ณด๊ฐ•์žฌ์™€๋Š” ๋‹ค๋ฅด๊ฒŒ ๊ธฐํ•˜ํ•™์  ํ˜•์ƒ, ์—ฐ์„ฑ, ํƒ„์„ฑ๊ณ„์ˆ˜

๋ฐ ๋ถ€์ฐฉ ํŠน์„ฑ์ด ์ผ๋ฅ ์ ์ด์ง€ ๋ชปํ•˜๊ธฐ ๋•Œ๋ฌธ์— GFRP rebar

๋ฅผ ํ™œ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์˜ ์„ค๊ณ„ ์‹œ ๊ฐ๊ฐ์˜ ํ˜•์ƒ์— ์ 

ํ•ฉํ•œ FRP rebar์˜ ์„ค๊ณ„์‹์ด ๊ฒ€ํ† ๋˜์–ด์•ผ ํ•  ํ•„์š”๊ฐ€ ์žˆ๋‹ค.

*Corresponding author E-mail : [email protected]

Received August 20, 2007, Accepted December 15, 2007

โ“’2008 by Korea Concrete Institute

Page 2: New Suggestion of Effective Moment of Inertia for Beams

186โ”‚ํ•œ๊ตญ์ฝ˜ํฌ๋ฆฌํŠธํ•™ํšŒ ๋…ผ๋ฌธ์ง‘ ์ œ20๊ถŒ ์ œ2ํ˜ธ (2008)

GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ํœจ๋ชจ๋ฉ˜

ํŠธ ์„ฑ๋Šฅ์€ ์ด๋ฏธ ๊ทธ ์šฐ์ˆ˜์„ฑ์ด ๊ตฌ๋ช…๋˜์–ด ์žˆ์œผ๋‚˜ GFRP์˜

๋‹จ์  ์ค‘ ํ•˜๋‚˜์ธ ์ฒ˜์ง์— ๋Œ€ํ•œ ์‚ฌ์šฉ์„ฑ ์ธก๋ฉด์€ ๊ฐœ์„ ๋˜์–ด์•ผ

ํ•  ์ ์œผ๋กœ ์ง€์ ๋˜๊ณ  ์žˆ๋‹ค. GFRP rebar์— ๋Œ€ํ•œ ์ฒ˜์ง๋Ÿ‰ ์˜ˆ

์ธก ๋ฌธ์ œ๋Š” Larralde11)๊ฐ€ ์—ฐ๊ตฌํ•œ ๋ฐ”์— ์˜ํ•˜๋ฉด GFRP rebar

์˜ ๊ฒฝ์šฐ, ํœจํ•˜์ค‘์˜ 30%๊นŒ์ง€๋Š” Branson7)์ด ์ œ์•ˆํ•œ ์œ ํšจ

๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ์‹์ด ๊ตฌ์กฐ ๊ฑฐ๋™์„ ์ถฉ๋ถ„ํžˆ ์˜ˆ์ธกํ•  ์ˆ˜

์žˆ๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ๋‹ค.

Nawy12)๋Š” FRP rebar๋กœ ํœจ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์˜ ์ฒ˜์ง

๋Ÿ‰์€ FRP rebar์˜ ๋ณด๊ฐ•๋น„์— ์˜ํ–ฅ์„ ๋ฐ›๋Š”๋‹ค๋Š” ์—ฐ๊ตฌ ๊ฒฐ๊ณผ

๋ฅผ ๋ณด์ด๊ณ  ์žˆ์œผ๋ฉฐ, 0.7%์˜ ๋ณด๊ฐ•๋น„๋ฅผ ๊ฐ–๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด๋Š”

๊ฑฐ์˜ 60%์˜ ์ฒ˜์ง๋Ÿ‰ ์ €ํ‰๊ฐ€๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š” ๋ฐ˜๋ฉด, 2.2%์˜ ๋ณด

๊ฐ•๋น„๋ฅผ ๋ณด์œ ํ•œ ๋ณด์˜ ๊ฒฝ์šฐ ์•ฝ 8% ์ด๋‚ด์˜ ์ฒ˜์ง๋Ÿ‰ ์˜ค์ฐจ๋ฅผ

๋ณด์ด๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„ํ•˜์˜€๋‹ค. ๋ณธ ์—ฐ๊ตฌ ๊ฒฐ๊ณผ๋กœ์„œ FRP rebar

๋กœ ๋ณด๊ฐ•๋œ ๋ณด์˜ ์ฒ˜์ง๋Ÿ‰ ์˜ˆ์ธก์€ FRP rebar์˜ ๋ณด๊ฐ•๋น„์— ์ „

์ ์œผ๋กœ ์˜์กดํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ๋‹ค.

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ž์ฒด ๊ฐœ๋ฐœ๋œ ์ดํ˜• GFRP rebar๋กœ ํœจ๋ณด

๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ๋ณด์˜ ๊ธฐ๋ณธ์ ์ธ ์„ค๊ณ„๋ณ€์ˆ˜ ์—ฐ๊ตฌ๋ฅผ ์œ„ํ•ด ์ฒ˜์ง

์˜ˆ์ธก์„ ์œ„ํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹์„ ์ œ์•ˆํ•˜๊ณ ์ž

ํ•œ๋‹ค. ์ด๋ฅผ ์œ„ํ•ด ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ๋ณด

์˜ ๋ณด๊ฐ•๋น„๋ณ„ ํœจ ์‹œํ—˜์ฒด๋ฅผ ์ œ์ž‘ํ•˜์—ฌ ๊ตฌ์กฐ ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜

์˜€๋‹ค.

2. ์‹คํ—˜ ๋ฐ ๊ฒฐ๊ณผ ๋ถ„์„

2.1 ์‹คํ—˜ ๊ฐœ์š” ๋ฐ ์‹คํ—˜ ๋ณ€์ˆ˜

๋ณธ ์—ฐ๊ตฌ์—์„œ ์ ์šฉ๋œ ์ดํ˜• GFRP ๋ณด๊ฐ•๊ทผ์€ ๋ถ€์ฐฉ ์„ฑ๋Šฅ

๊ฐœ์„ ์„ ์œ„ํ•˜์—ฌ Fig. 1๊ณผ ๊ฐ™์ด ํ‘œ๋ฉด์— ํ˜•์„ฑ๋œ ์ดํ˜•์ฒ ๊ทผ๊ณผ

๊ฐ™์€ ์ดํ˜• ๋ฆฌ๋ธŒ๋ฅผ ์ œ์ž‘ํ•˜๊ธฐ์œ„ํ•ด ์œ ๋ฆฌ์„ฌ์œ  (milled glass

fiber)์™€ ์—ํญ์‹œ๋ฅผ 50๋Œ€50์œผ๋กœ ํ˜ผํ•ฉํ•˜์—ฌ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ์•ฝ

160oC ์ด์ƒ์˜ ์˜จ๋„๋กœ 15๋ถ„ ์ •๋„ ๊ณ ์˜จ ์–‘์ƒํ•˜์—ฌ ์ œ์ž‘๋˜

์—ˆ๋‹ค. ์™ธ๋ถ€ ์ดํ˜• ๋ฆฌ๋ธŒ์˜ ๋ฐฐ์น˜ ๊ฐ๋„๋Š” ์•ฝ 80o๋กœ ํ•˜์˜€์œผ๋ฉฐ,

์ œ์ž‘๋œ ์ดํ˜• GFRP rebar๋Š” FRP ์„ฑํ˜• ์ œํ’ˆ์˜ ์ œ์กฐ ๋ฐฉ๋ฒ•

์ค‘ ๋งˆ๊ฐ์„ฑ์˜ ์ฆ์ง„์„ ์œ„ํ•˜์—ฌ ์ฃผ๋กœ ์‚ฌ์šฉ๋˜๋Š” ์‚ฌ์ถœ์„ฑํ˜•๋ฒ•

(injection molding)์„ ์ ์šฉํ•˜์˜€๋‹ค.

Table 1์€ ์ดํ˜• GFRP rebar ์ œ์ž‘์— ์‚ฌ์šฉ๋œ ๋งคํŠธ๋ฆญ์Šค์™€

์œ ๋ฆฌ์„ฌ์œ ์˜ ๋ฌผ์„ฑ์น˜๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ ์‚ฌ์šฉ๋œ ์ด

ํ˜• GFRP rebar๋Š” ๊ณต์นญ์ง๊ฒฝ์ด D10์ด๊ณ , ์„ค๊ณ„ ์ธ์žฅ๊ฐ•๋„๊ฐ€

fd,GFRP = 616 MPa์ธ ์ œํ’ˆ์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค1).

Table 2๋Š” ๋ณธ ์—ฐ๊ตฌ์— ์ ์šฉ๋œ ํœจ ๋ณด๊ฐ•๋น„ ์„ค๊ณ„๋ฅผ ๋‚˜ํƒ€๋‚ด

๊ณ  ์žˆ๋‹ค. ๋ณด๊ฐ• ํšจ๊ณผ ๋ฐ ํŒŒ๊ดด ๋ชจ๋“œ ๋ถ„์„์„ ์œ„ํ•˜์—ฌ ACI

440 guideline ์— ์˜ํ•ด ๊ณ„์‚ฐ๋œ ๊ท ํ˜•๋ณด๊ฐ•๋น„ 0.0059๋ฅผ ๊ธฐ์ค€

์œผ๋กœ ๊ฐ๊ฐ ์ €๋ณด๊ฐ• (FSR2), ๊ท ํ˜•๋ณด๊ฐ• (FSR3), ๊ณผ๋ณด๊ฐ•

(FSR4) ๋‹จ๋ฉด์ด ๋˜๋„๋ก ์„ค๊ณ„ํ•˜์˜€๋‹ค. Fig. 2๋Š” ๋ณธ ์—ฐ๊ตฌ์—์„œ

์ˆ˜ํ–‰๋œ ํœจ ์žฌํ•˜ ์‹คํ—˜์˜ ๊ฐœ์š”๋„๋ฅผ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ๊ฐ€๋ ฅ์€

4์  ํœจ ์žฌํ•˜ ์‹œํ—˜์„ ์ ์šฉํ•˜์˜€์œผ๋ฉฐ ํ•˜์ค‘๊ฐ€๋ ฅ์€ MTS์‚ฌ์˜

250 kN ์šฉ๋Ÿ‰์˜ ์œ ์••์‹ ํ•˜์ค‘๊ฐ€๋ ฅ๊ธฐ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ 1 mm/min

์˜ ๋ณ€์œ„ ์ œ์–ด๋ฅผ ์‹ค์‹œํ•˜์˜€๊ณ , ํœจ ํŒŒ๊ดด๋ฅผ ์œ ๋„ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ

3.7์˜ ์ „๋‹จ์ŠคํŒฌ๋น„ (a/d)๋ฅผ ์ ์šฉํ•˜์˜€๋‹ค. ํœจ ๋ณด๊ฐ•๊ทผ์˜ ์ ์šฉ

์€ Fig. 2์˜ ๋ฐฐ๊ทผ๋„์™€ ๊ฐ™์ด ์ธ์žฅ๋ถ€์— D10 ์ดํ˜• GFRP

rebar๋ฅผ ๋ฐฐ๊ทผํ•˜์˜€์œผ๋ฉฐ, ์••์ถ•๋ถ€์˜ ๊ฒฝ์šฐ, fy = 300 MPa์˜ D10

์˜ ์••์ถ•์ฒ ๊ทผ์„ ๋ฐฐ๊ทผํ•˜์˜€๋‹ค. ๋˜ํ•œ ์ „๋‹จ์— ์˜ํ•œ ์กฐ๊ธฐํŒŒ๊ดด

Fig. 1 Newly-developed GFRP rebar and steel rebar

Table 1 The material properties of E-glass fiber and epoxy resin8)

Epoxy

resin

Fibers

(E-glass)

Tensile

Strength (MPa) 74* 1,840*

Modulus of elasticity (GPa) 2.73* 75.00*

Elongation (%) 5%* 1.3%*

Compressive

Strength (MPa) 53 -

Modulus of elasticity (GPa) 5.23 -

Elongation (%) 1% -

FlexuralStrength (MPa) 123* -

Modulus of elasticity (GPa) 3.03* -

Specific weight (g/m3) 1.18* 2.50*

Water absorption (%) 3.01* -

*Provided by manufacturer

Table 2 The flexural design of reinforcement for the test beams

SpecimensReinforcing

material

Reinforcing ratio Design of GFRP

reinforcementActual Balanced

FSR2 GFRP 0.00427 0.0059 Under reinforced

FSR3 GFRP 0.00640 0.0059 Balanced

FSR4 GFRP 0.00927 0.0059 Over reinforced

Page 3: New Suggestion of Effective Moment of Inertia for Beams

์ดํ˜• GFRP Rebar๋กœ ๋ณด๊ฐ•๋œ ๋ณด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹ ์ œ์•ˆโ”‚187

๋ฅผ ๋ฐฉ์ง€ํ•˜๊ณ ์ž D10 ์ „๋‹จ๋ณด๊ฐ•๊ทผ์„ 100 mm ๊ฐ„๊ฒฉ์œผ๋กœ ๋ณด

์ „ ์ง€๊ฐ„์— ๋ฐฐ๊ทผํ•˜์˜€๋‹ค.

2.2. ๊ตฌ์กฐ ์‹คํ—˜ ๊ฒฐ๊ณผ

Fig. 3๋Š” ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ๋ณ€์ˆ˜์‹œํ—˜์ฒด์— ๋Œ€

ํ•œ ๋ณด๊ฐ•๋น„์— ๋”ฐ๋ฅธ ํ•˜์ค‘-์ฒ˜์ง๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ฃผ๋Š” ๊ทธ๋ฆผ์ด๋‹ค.

๊ทธ๋ฆผ์—์„œ ๋ณด์ด๋“ฏ์ด ๋ณด๊ฐ•๋Ÿ‰์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ „์ฒด์ ์ธ ๊ฐ•์„ฑ

์€ ์ฆ์ง„๋˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ดˆ๊ธฐ ๊ท ์—ดํ•˜์ค‘์˜ ๊ฒฝ์šฐ๋„

๊ฑฐ์˜ ์œ ์‚ฌํ•œ ๊ฐ’์„ ๋ณด์˜€์œผ๋ฉฐ ๋ชจ๋“  ์‹œํ—˜์ฒด๊ฐ€ ๊ทนํ•œ๊ฐ•๋„์—

๋„๋‹ฌํ•œ ํ›„ ์ตœ์ข… ํŒŒ๊ดด ๋ณ€์œ„๊นŒ์ง€ ๊พธ์ค€ํ•œ ๋ณ€์œ„์˜ ์ฆ๊ฐ€๋ฅผ ๋ณด

์ด๋Š” ๊ฒƒ์œผ๋กœ ํ™•์ธ๋˜์—ˆ๋‹ค. ๋ชจ๋“  ๋ณ€์ˆ˜ ์‹œํ—˜์ฒด๋Š” ์‘๋ ฅ ์ฆ๊ฐ€

์— ๋”ฐ๋ฅธ ๊ธ‰๊ฒฉํ•œ ํ•˜์ค‘ ์ €ํ•˜๋Š” ๋ฐœ์ƒํ•˜์ง€ ์•Š์•˜์œผ๋ฉฐ FSR2

์™€ FSR4 ์‹œํ—˜์ฒด์˜ ๊ฒฝ์šฐ, ๊ทนํ•œ๊ฐ•๋„ ๋„๋‹ฌ ํ›„ ์ˆœ๊ฐ„์ ์ธ ํ•˜

์ค‘ ์ €ํ•˜๋ฅผ ๋ณด์˜€์œผ๋‚˜ ์ทจ์„ฑ์  ๊ฑฐ๋™์€ ๋ณด์ด์ง€ ์•Š์•˜์œผ๋ฉฐ ์ „

๋ฐ˜์ ์ธ ๊ตฌ์กฐ๊ฑฐ๋™์—๋Š” ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜์ง€ ๋ชปํ•˜์˜€๋‹ค.

๋‹ค์Œ์˜ Table 3์€ ๊ฐ ์‹œํ—˜์ฒด์˜ ๊ทนํ•œํ•˜์ค‘ ๋ฐ ํœจ๋ชจ๋ฉ˜ํŠธ,

ํŒŒ๊ดด ๋ชจ๋“œ๋ฅผ ํ‘œ๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์„ค๊ณ„์‹œ ์˜ˆ์ƒํ•œ ๊ฒƒ๊ณผ ๊ฐ™์ด

FSR2 ์‹œํ—˜์ฒด๋Š” ํœจ์ธ์žฅํŒŒ๊ดด ๋˜์—ˆ์œผ๋ฉฐ, FSR3๊ณผ FSR4 ์‹œ

ํ—˜์ฒด๋Š” ๊ฐ๊ฐ ํœจ์••์ถ•ํŒŒ๊ดด ๋˜์—ˆ๋‹ค. ํœจ๋ชจ๋ฉ˜ํŠธ์˜ ํ•ด์„์€ ACI

440 guideline5)์„ ๊ธฐ์ค€์œผ๋กœ ์‚ฐ์ •ํ•˜์˜€์œผ๋ฉฐ, ํ•ด์„ ๊ฒฐ๊ณผ ์‹ค

ํ—˜๊ฐ’์— ๋น„ํ•ด ๋‹ค์†Œ ๋ณด์ˆ˜์ ์ธ ๊ฒƒ์œผ๋กœ ํ‰๊ฐ€๋˜์—ˆ๋‹ค1).

3. ๊ธฐ์กด์‹์— ์˜ํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ๋ฐ ์ฒ˜์ง๋Ÿ‰ ๋ถ„์„

3.1 ๊ฐœ์š”

RC ๋ณด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜์™€ ํ•จ๊ป˜ ํœจ ๋ถ€

์žฌ์˜ ๊ฐ•์„ฑ์„ ๊ฒฐ์ •ํ•˜๋Š” ์ฃผ์š” ์ธ์ž์ด๋ฉฐ, ๋ถ€์žฌ์˜ ๊ฐ•์„ฑ์€ ์ฒ˜

์ง ๋ฐ ๊ท ์—ด ๋“ฑ ์‚ฌ์šฉ์„ฑ์— ์˜ํ–ฅ์„ ๋ฏธ์นœ๋‹ค. ๋”ฐ๋ผ์„œ ๋ถ€์žฌ์˜

์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ์˜ ์‚ฐ์ •์€ ๋ถ€์žฌ์˜ ์‚ฌ์šฉ์„ฑ์„ ์˜ˆ์ธกํ•˜๋Š”

๋ฐ ์žˆ์–ด ๋งค์šฐ ์ค‘์š”ํ•˜๋‹ค. ์ผ๋ฐ˜์ ์ธ RC ๋ณด๋Š” Branson7)์ด

์ œ์•ˆํ•œ ์•„๋ž˜์˜ ์‹ (1)์„ ์‚ฌ์šฉํ•œ๋‹ค.

<= Ig (1)

์—ฌ๊ธฐ์„œ Ic = The effective moment of inertia

Mcr = The cracking moment (frIg / yt)

Ma = The service moment

Ig = The gross moment of inertia

Icr = The transformed cracked-section moment of inertia

ํ•˜์ง€๋งŒ ์‹ (1)์„ GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ํœจ ๋ถ€์žฌ์— ์ ์šฉ

ํ•  ๊ฒฝ์šฐ GFRP rebar์˜ ๋‚ฎ์€ ๊ฐ•์„ฑ์œผ๋กœ ์ธํ•œ ์‚ฌ์šฉ์„ฑ ์ €ํ•˜

๋ฐ ์ฒ˜์ง์— ๋Œ€ํ•œ ๊ณผ์†Œํ‰๊ฐ€์— ์šฐ๋ ค๊ฐ€ ์žˆ๋‹ค3). ์ด๋Ÿฌํ•œ ๋ฌธ์ œ

์ ์„ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•˜์—ฌ GFRP rebar์— ์ ์šฉ๊ฐ€๋Šฅํ•œ ์œ ํšจ๋‹จ

๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹์ด ์—ฌ๋Ÿฌ ์—ฐ๊ตฌ์ž๋“ค์— ์˜ํ•ด ์ œ์‹œ๋˜์—ˆ

๋‹ค4,7,9)

. ๊ทธ๋Ÿฌ๋‚˜ ์ด๋Ÿฌํ•œ ์ œ์•ˆ์‹ ๋˜ํ•œ GFRP rebar์˜ ์ œ์ž‘

๋ฐฉ๋ฒ• ๋ฐ ํ‘œ๋ฉด ํ˜•์ƒ, ๋ฌผ์„ฑ ๋“ฑ์ด ์ œํ’ˆ๋ณ„๋กœ ์ฐจ์ด๊ฐ€ ์žˆ๊ธฐ ๋•Œ

๋ฌธ์— ๋ชจ๋“  GFRP rebar์— ์ผ๋ฐ˜ํ™”ํ•˜์—ฌ ์ ์šฉํ•˜๊ธฐ๋Š” ๋‹ค์†Œ ์–ด

๋ ค์›€์ด ๋งŽ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ตœ๊ทผ ์ œ์•ˆ๋œ GFRP

rebar์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ์‹์„ ๋ณธ ์‹คํ—˜ ๊ฒฐ๊ณผ์™€ ๋น„

๊ตํ•œ ํ›„, ๋ณธ ์—ฐ๊ตฌ์—์„œ ๊ฐœ๋ฐœ๋œ ์ดํ˜• GFRP rebar์— ์ ์šฉ

๊ฐ€๋Šฅํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„์‹์„ ์ œ์•ˆํ•˜๊ณ ์ž ํ•œ๋‹ค.

3.2 ๊ธฐ์กด ํ•ด์„ ๋ชจ๋ธ์˜ ์ ์šฉ

์‹œํ—˜๊ฐ’๊ณผ์˜ ๋น„๊ต๋ฅผ ์œ„ํ•œ ๊ธฐ์กด ์—ฐ๊ตฌ์‹์€ ACI 440 guideline5),

ISIS Canada Design Manual10)์—์„œ ์ œ์‹œํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ

๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹๊ณผ Toutanji et al.9)์ด ์ œ์•ˆํ•œ ์‹์„ ์ ์šฉํ•˜

์˜€์œผ๋ฉฐ, ์ด๋Š” ์‹ (3)~(6)์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์‹ (2)๋Š” ์‹คํ—˜๊ฐ’์—

๋Œ€ํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ๊ณ„์‚ฐ์‹์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

(2)

Ie

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3Ig 1

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3

โ€“โŽ โŽ โŽ› โŽž Icrโ‹…+=

Ie exp( )

P exp2 aโ‹…โ„

24Ecโˆ† exp

------------------------- 3L2

4a2

โ€“( )=

Fig. 2 The test setup and details of the test beams

Fig. 3 Load-deflection relationship of the concrete beam

reinforced with the GFRP rebar

Table 3 The summary of the test result

SpecimensUltimate

load (kN)

Flexural moment (kNยทm)Mode of failure

Experiment Analysis

FSR2 57 19.5 12.1 Flexural tension

FSR3 64 22.0 18.1Flexural

compression

FSR4 74 25.4 20.8Flexural

compression

Page 4: New Suggestion of Effective Moment of Inertia for Beams

188โ”‚ํ•œ๊ตญ์ฝ˜ํฌ๋ฆฌํŠธํ•™ํšŒ ๋…ผ๋ฌธ์ง‘ ์ œ20๊ถŒ ์ œ2ํ˜ธ (2008)

์—ฌ๊ธฐ์„œ a : span to depth ratio

L : span length

โˆ†exp : deflection (exp.)

ACI 440 guideline;

<= Ig (3)

์—ฌ๊ธฐ์„œ

ISIS Canada Design Manual;

(4)

Toutanji et all9);

for

<= Ig

(5)

for

<= Ig (6)

Table 4๋Š” ACI 440 guideline5), ISIS Canada Design

Manual10)

๋ฐ Toutanji et al.9)์˜ ์ œ์•ˆ ๋ชจ๋ธ์„ ์ ์šฉํ•˜์—ฌ ์œ ํšจ

๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ-์ ์šฉ๋ชจ๋ฉ˜ํŠธ ๊ด€๊ณ„๋ฅผ ๋ถ„์„ํ•˜๊ธฐ ์œ„ํ•ด ์ ์šฉ

๋œ ํ•ด์„ ๋ณ€์ˆ˜๋“ค์„ ์ •๋ฆฌํ•œ ํ‘œ์ด๋‹ค. ๋ณธ ํ•ด์„ ๋ณ€์ˆ˜๋“ค์„ ์‚ฌ

์šฉํ•˜์—ฌ ์–ป์–ด์ง„ ๊ฒฐ๊ณผ๋Š” Figs. 4~6์— ๋‚˜ํƒ€๋‚˜์žˆ๋‹ค.

์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ๋ถ„์„ ๊ฒฐ๊ณผ, FSR2, FSR3 ๋ฐ FSR4 ์‹œ

ํ—˜์ฒด ๋ชจ๋‘ ACI 440 guideline5) ๋ฐ Toutanji et al.

9)์˜ ํ•ด์„

์‹๊ณผ๋Š” ๋น„๊ต์  ์‹คํ—˜ ๊ฒฐ๊ณผ์™€ ์œ ์‚ฌํ•œ ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด๋Š” ๋ฐ˜๋ฉด,

ISIS Canada Design Manual10)์˜ ํ•ด์„์‹์€ ์ดˆ๊ธฐ๊ท ์—ด ์งํ›„,

๋ณ€๊ณก์  ๋ถ€๊ทผ์—์„œ ๋‹ค๋ฅธ ๋ชจ๋ธ๋“ค์— ๋น„ํ•ด ๊ธ‰๊ฒฉํ•œ ์ €ํ•˜ ํ˜„์ƒ์„

๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋‚˜, ์ดํ›„ ๊ทนํ•œ์ƒํƒœ์— ๋„๋‹ฌํ• ์ˆ˜๋ก ๋‹ค๋ฅธ ํ•ด์„ ๋ชจ

๋ธ๋“ค์— ์ˆ˜๋ ดํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

3.3 ๊ธฐ์กด ๋ชจ๋ธ์˜ ์ ์šฉ์„ ํ†ตํ•œ ์ฒ˜์ง๋Ÿ‰ ๋ถ„์„

FRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์˜ ๊ตฌ์กฐ ๊ฑฐ๋™์€ ๊ธฐ

์กด ์ฒ ๊ทผ ๋ณด๊ฐ• ์‹œํ—˜์ฒด์™€๋Š” ๋‹ฌ๋ฆฌ ์ดˆ๊ธฐ๊ท ์—ด์— ์˜ํ•œ ๊ฐ•์„ฑ ์ €

ํ•˜ ํ›„ ๋šœ๋ ทํ•œ ์ฐจํ›„ ๊ฐ•์„ฑ์ €ํ•˜ ์—†์ด ํŒŒ๊ดด์‹œ๊นŒ์ง€ ์„ ํ˜• ๊ฑฐ

๋™์ด ์ง€๋ฐฐ์ ์œผ๋กœ ๋‚˜ํƒ€๋‚œ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” FRP

rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์˜ ์ฒ˜์ง๋Ÿ‰ ์˜ˆ์ธก ์‹œ ์ฒ˜์ง๋Ÿ‰์„

๋น„๊ต์  ์†์‰ฝ๊ฒŒ ์˜ˆ์ธกํ•  ์ˆ˜ ์žˆ๋Š” ์„ ํ˜•ํ•ด์„์‹์„ ์ ์šฉํ•˜์˜€์œผ

๋ฉฐ ์ด๋Š” ์‹ (6)์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋”ฐ๋ผ์„œ ์•ž์„œ ๋ถ„์„๋œ ์œ ํšจ

๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„๊ฐ’์„ ์ ์šฉํ•˜์—ฌ ์‹ (1)์˜ ์—ญ์‚ฐ์„ ํ†ต

ํ•˜์—ฌ ์‹ (7)์„ ๊ตฌํ•˜์—ฌ ์ฒ˜์ง๋Ÿ‰์„ ๊ณ„์‚ฐํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ๋Š”

Figs. 7~9์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Ie

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3ฮฒdIg 1

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3โ€“โŽ โŽ 

โŽ› โŽž Icrโ‹…+=

ฮฒd ฮฑb

Ef

Es

----- 1+โŽ โŽ โŽ› โŽž ฮฑb, 0.5= =

Ie

IgIcr

Icr 1 0.5Mcr

Ma

--------โŽ โŽ โŽ› โŽž 2โ€“โŽ โŽ 

โŽ› โŽž Ig Icrโ€“( )+

-----------------------------------------------------------------------=

EFRP

Es

------------ฯFRP 0.003 ,<

Ie

Mcr

Ma

--------โŽ โŽ โŽ› โŽž

610ฯ

FRPEFRP

Es

-------------------------------โ€“

Ig 1Mcr

Ma

--------โŽ โŽ โŽ› โŽž

610ฯ

FRPEFRP

Es

-------------------------------โ€“

โ€“

โŽ โŽ โŽœ โŽŸโŽœ โŽŸโŽ› โŽž

Icrโ‹…+=

EFRP

ES

------------ฯFRP 0.003 ,โ‰ฅ

Ie

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3Ig 1

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3

โ€“โŽ โŽ โŽ› โŽž Icrโ‹…+=

Table 4 Analysis parameters for calculating the moment of

inertia

FSR2 FSR3 FSR4

Centriod, x 16.40 19.90 22.10

yt (mm) 213.60 210.20 207.90

Ig (mm4) 182,505,000 182,505,000 182,505,000

Mcr (kNยทm) 2.66 2.71 2.74

Icr (mm4) 8,288,067 11,966,056 13,738,339

Fig. 4 The comparison of the moment of inertia by using the

conventional equation for FSR2 specimen

Fig. 5 The comparison of the moment of inertia by using the

conventional equation for FSR3 specimen

Fig. 6 The comparison of the moment of inertia by using the

conventional equation for FSR4 specimen

Page 5: New Suggestion of Effective Moment of Inertia for Beams

์ดํ˜• GFRP Rebar๋กœ ๋ณด๊ฐ•๋œ ๋ณด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹ ์ œ์•ˆโ”‚189

(7)

์ฒ˜์ง๋Ÿ‰ ๋ถ„์„ ๊ฒฐ๊ณผ FSR2 ๋ฐ FSR3 ์‹œํ—˜์ฒด์˜ ๊ฒฝ์šฐ ๊ทนํ•œ

๋ชจ๋ฉ˜ํŠธ์˜ ์•ฝ 50% ์ˆ˜์ค€๊นŒ์ง€๋Š” ๋น„๊ต์  ์œ ์‚ฌํ•œ ๊ฑฐ๋™์„ ๋‚˜

ํƒ€๋‚ด์—ˆ์œผ๋‚˜, ์ดํ›„ ๊ทนํ•œ๋ชจ๋ฉ˜ํŠธ ๋„๋‹ฌ์‹œ๊นŒ์ง€๋Š” ๋‹ค์†Œ ํฐ ์ฐจ

์ด๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. FSR4 ์‹œํ—˜์ฒด์˜ ๊ฒฝ์šฐ, ๋‹ค๋ฅธ ์‹œํ—˜์ฒด์—

๋น„ํ•ด ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„๊ฐ’์ด ์ „๋ฐ˜์ ์œผ๋กœ ๋‚ฎ์€ ๊ฐ’

์„ ๋‚˜ํƒ€๋‚ด์—ˆ๊ธฐ ๋•Œ๋ฌธ์— ์ฒ˜์ง ํ•ด์„์˜ ๊ฒฝ์šฐ๋„ ์‹คํ—˜๊ฐ’์— ๋น„

ํ•ด ๋‹ค์†Œ ๋‚ฎ์€ ๊ฐ•์„ฑ ํšจ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ

๋ณด ๊ตฌ์กฐ๋ฌผ์˜ ํ•ฉ๋ฆฌ์ ์ธ ์ฒ˜์ง ์˜ˆ์ธก์„ ์œ„ํ•ด ์ดํ˜• GFRP

rebar์˜ ๊ตฌ์กฐ ํŠน์„ฑ์— ์ ํ•ฉํ•œ ํ•ด์„ ๋ชจ๋ธ๋กœ์˜ ๊ฐœ์„  ๋ฐ ์ 

์šฉ์ด ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

4. ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹ ์ œ์•ˆ ๋ฐ ์ฒ˜์ง๋Ÿ‰ ๋ถ„์„

๋ณธ ์—ฐ๊ตฌ์—์„œ ์ œ์•ˆํ•˜๊ณ ์ž ํ•˜๋Š” ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ๋ชจ

๋ธ์€ Toutanji et al9)์ด ์ œ์•ˆํ•œ ํ•ด์„ ๋ชจ๋ธ์„ ๊ธฐ์ดˆํ•˜์˜€๋‹ค.

ISIS Canada Design Manual10)

๋ชจ๋ธ์˜ ๊ฒฝ์šฐ, ์ดˆ๊ธฐ๊ท ์—ด

์ดํ›„ ์‹คํ—˜๊ฐ’์— ๋Œ€ํ•œ ์˜ˆ์ธก์ด ๋‹ค์†Œ ์–ด๋ ค์šด ์ธก๋ฉด์ด ์žˆ๋‹ค.

ACI 440 guideline5) ํ•ด์„ ๋ชจ๋ธ์˜ ๊ฒฝ์šฐ, ์‹คํ—˜์ƒ์ˆ˜์ธ ฮฑ,ฮฒ

๋ฅผ ๊ฒฝํ—˜์ ์œผ๋กœ ๋„์ถœํ•˜์—ฌ ์ œ์•ˆํ•˜์˜€์œผ๋‚˜ ์‹คํ—˜์ƒ์ˆ˜๋ฅผ ์ •๋Ÿ‰

ํ™”ํ•˜๊ธฐ์—๋Š” ๋‹ค์†Œ ์–ด๋ ค์›€์ด ์žˆ๋‹ค. ์ด์— GFRP์˜ ๋ณด๊ฐ•๋น„

์‚ฐ์ • ์‹œ ๋‹จ์ˆœํ•œ ์ง๊ฒฝ๊ณผ ๋‹จ๋ฉด์„ ์œ„์ฃผ๋กœ ํ•œ ๋ณด๊ฐ•๋น„ ์ ์šฉ

๋ณด๋‹ค๋Š” ์ฒ ๊ทผ๋ณด๊ฐ•๋น„๋กœ ํ™˜์‚ฐํ•˜์—ฌ ์ ์šฉํ•˜๋Š” ๊ฒƒ์ด ๋ฐ”๋žŒ์งํ•œ

๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” Toutanji et al.9)

์ด ์ œ์•ˆํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„ ๋ชจ๋ธ์„ ๋ฐ”ํƒ•์œผ๋กœ ์ฒ 

๊ทผ๊ณผ ์ดํ˜• GFRP rebar์˜ ๋ณด๊ฐ•๋น„ ๋ฐ ํƒ„์„ฑ๊ณ„์ˆ˜๋น„์— ๋Œ€ํ•œ

์ ์šฉ ๋ฒ”์œ„๋ฅผ ์ ์šฉํ•œ ๋ณ€์ˆ˜ ํ•ด์„์„ ํ†ตํ•ด ํ™œํ•˜์ค‘๋ชจ๋ฉ˜ํŠธ์™€

๊ท ์—ด๋ชจ๋ฉ˜ํŠธ๊ฐ€ ๋ฐ˜์˜๋œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„์‹์„ ์ œ

์•ˆํ•˜๊ณ ์ž ํ•œ๋‹ค.

4.1 GFRP Rebar๋กœ ํœจ๋ณด๊ฐ•๋œ ๋ณด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜

ํŠธ ์ œ์•ˆ์‹

์‹ (8)๊ณผ (9)๋Š” Branson7)์ด ์ œ์•ˆํ•œ ๊ท ์—ด์ด ๋ฐœ์ƒ๋œ ์ฒ ๊ทผ

์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด์—์„œ์˜ ์œ ํšจ๋‹จ๋ฉด ์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„์‹์ด๋‹ค. ์ง€

์ˆ˜ m๊ฐ’์€ ์‹œํ—˜์„ ํ†ตํ•ด ์–ป์–ด์ง„ 3์ด ์‚ฌ์šฉ๋œ๋‹ค.

<= Ig (8)

(9)

์—ฌ๊ธฐ์„œ Ie(exp) = the moment of inertia from the test result

์œ„์˜ ์‹์„ ๋ฐ”ํƒ•์œผ๋กœ GFRP rebar์˜ ๋ณด๊ฐ•๋น„ ฯFRP์™€ ํƒ„

์„ฑ๊ณ„์ˆ˜ EFRP๋ฅผ ๊ณ ๋ คํ•œ ํšŒ๊ท€๋ถ„์„์„ ์‹ค์‹œํ•œ ์ง€์ˆ˜ m๊ฐ’์€

๋‹ค์Œ ์‹ (10)~(12)์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋ณด๊ฐ•๋น„์— ๊ฒฝ๊ณ„์ ์˜ ๊ฒฝ

์šฐ, Toutanji et al.9)์ด Branson

7)์˜ ์ œ์•ˆ์‹์— ๊ทผ๊ฑฐํ•˜์—ฌ

Yost13)

, ๋ฐ Benmokrane6) ๋“ฑ ๊ธฐ์กด ์—ฐ๊ตฌ์ž๋“ค์˜ ๋‹ค์ˆ˜์˜ ์‹ค

ํ—˜ ๊ฒฐ๊ณผ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ๋„์ถœํ•œ 1% ๋ณด๊ฐ•๋น„ ๊ฒฝ๊ณ„์กฐ๊ฑด์„ ๊ณ ๋ ค

ํ•˜์—ฌ ์ดํ˜• GFRP์˜ ํƒ„์„ฑ๊ณ„์ˆ˜์™€ ๋ณด๊ฐ• ์‹œํ—˜์ฒด์˜ ๋ณด๊ฐ•๋น„๋ฅผ

์ ์šฉํ•จ์œผ๋กœ์จ ๊ฒฐ์ •๋˜์—ˆ๋‹ค.

for (10)

for (11)

์—ฌ๊ธฐ์„œ ฯFRP = the reinforcing ratio of the specimen reinforced

with the GFRP rebar

โˆ† P aโ‹…24EcIc

---------------- 3L2

4a2

โ€“( )=

Ie

Mcr

Ma

--------โŽ โŽ โŽ› โŽžm

Ig 1Mcr

Ma

--------โŽ โŽ โŽ› โŽžm

โ€“โŽ โŽ โŽ› โŽž Icrโ‹…+=

mIe exp( ) Icrโ€“( )/ Ig Icr+( )[ ]log

Mcr

Ma

--------โŽ โŽ โŽ› โŽžlog

--------------------------------------------------------------------=

EFRP

Es

------------ฯFRP 0.0025,< m 613EFRP

Es

------------------ฯFRPโ€“=

EFRP

Es

------------ฯFRP 0.025 m,โ‰ฅ 3=

Fig. 7 The evaluation of the deflection for FSR2 specimen

Fig. 8 The evaluation of the deflection for FSR3 specimen

Fig. 9 The evaluation of the deflection for FSR4 specimen

Page 6: New Suggestion of Effective Moment of Inertia for Beams

190โ”‚ํ•œ๊ตญ์ฝ˜ํฌ๋ฆฌํŠธํ•™ํšŒ ๋…ผ๋ฌธ์ง‘ ์ œ20๊ถŒ ์ œ2ํ˜ธ (2008)

EFRP = the modulus of elasticity of the GFRP rebar

ES = the modulus of elasticity of the steel rebar

์œ„์™€ ๊ฐ™์ด ๋„์ถœ๋œ ์ง€์ˆ˜ m๊ฐ’๊ณผ ๊ทนํ•œ๋ชจ๋ฉ˜ํŠธ์˜ 50% ์ด

ํ›„์˜ ํ•˜์ค‘ ์ค‘๊ฐ€์— ๋”ฐ๋ฅธ ์ฒ˜์ง๋Ÿ‰์„ ๊ณ ๋ คํ•˜๋ฉด ์•„๋ž˜ ์‹ (12)

์™€ (13)์œผ๋กœ ์žฌ๊ตฌ์„ฑ ํ•  ์ˆ˜ ์žˆ๋‹ค.

for

<= Ig (12)

for

<= Ig

(13)

4.2 ์ œ์•ˆ๋œ ์‹์„ ์ ์šฉํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ๋ฐ ์ฒ˜์ง๋Ÿ‰

ํ‰๊ฐ€

Figs. 10~12๋Š” FSR2, FSR3 ๋ฐ FSR4 ์‹œํ—˜์ฒด์— ๋Œ€ํ•˜์—ฌ,

์ƒˆ๋กœ ์ œ์•ˆ๋œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด์„์‹์„ ์ ์šฉํ•œ ๋ชจ๋ฉ˜

ํŠธ-์ฒ˜์ง๊ด€๊ณ„๋ฅผ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ACI318์— ๊ทœ์ •๋˜์–ด์žˆ๋Š”

ํ•ด์„์‹์œผ๋กœ์„œ Branson7)์ด ์ œ์•ˆํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ํ•ด

์„์‹์˜ m๊ฐ’์ด 3์ธ ๊ฒฝ์šฐ, GFRP๋กœ ๋ณด๊ฐ•๋œ ๋ณด ๊ตฌ์กฐ๋ฌผ์˜ ๋ชจ

๋ฉ˜ํŠธ-์ฒ˜์ง๊ด€๊ณ„๋ฅผ ๊ณผ๋Œ€ํ‰๊ฐ€ ํ•  ์ˆ˜ ์žˆ๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ

๋‹ค. ๋˜ํ•œ ๋ณธ ์‹คํ—˜ ๊ฒฐ๊ณผ, (EFRP / Es)ฯFRP ๋ณด๊ฐ•๋น„ ํ™˜์‚ฐ๊ฐ’์˜

๊ฒฝ์šฐ, ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ œ์•ˆํ•œ 0.0025 ์ดํ•˜์˜ ๊ฐ’์„ ๋ณด์ด๋Š” ๊ฒƒ

์œผ๋กœ ๋ถ„์„๋˜์—ˆ์œผ๋ฉฐ, ์ด๋กœ ์ธํ•ด ์‹ (12)๋ฅผ ์ ์šฉํ•˜์—ฌ ๊ฐ ์‹œ

ํ—˜์ฒด์— ๋Œ€ํ•ด ๋ชจ๋ฉ˜ํŠธ-์ฒ˜์ง๊ด€๊ณ„๋ฅผ ๋„์‹œํ•œ ๊ทธ๋ฆผ์ด Figs. 10~12

์— ๋‚˜ํƒ€๋‚˜์žˆ๋‹ค. ํ•ด์„ ๊ฒฐ๊ณผ, ์ œ์•ˆ์‹์— ์˜ํ•œ moment-deflection

๊ด€๊ณ„๋Š” ๊ทนํ•œํ•˜์ค‘ 50% ์ดํ›„์˜ ๊ตฌ์กฐ ๊ฑฐ๋™์— ๋Œ€ํ•˜์—ฌ ๊ทนํ•œํ•˜

์ค‘์‹œ๊นŒ์ง€ ์‹คํ—˜๊ฐ’๊ณผ ๊ฑฐ์˜ ์œ ์‚ฌํ•œ ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด๋Š” ๊ฒƒ์œผ๋กœ

๋ถ„์„๋˜์—ˆ๋‹ค.

5. ๊ฒฐ ๋ก 

FRP rebar๋กœ ํœจ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด๋Š” ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ

๋ฆฌํŠธ ๋ณด์— ๋น„ํ•ด ๋†’์€ ๊ทนํ•œํ•˜์ค‘๊ณผ ๊ฒฝ๋Ÿ‰ํ™” ๋ฐ ๋‚ด๋ถ€์‹์„ฑ ๋“ฑ

๋งŽ์€ ์žฅ์ ์„ ์ง€๋‹ˆ๊ณ  ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ฒ ๊ทผ ๋Œ€๋น„ ๋‚ฎ์€ ํƒ„์„ฑ

๊ณ„์ˆ˜๋กœ ์ธํ•˜์—ฌ ๊ท ์—ด๊ณผ ์ฒ˜์ง์ด ๋‹ค์†Œ ํฐ ๊ฒฝํ–ฅ์ด ์žˆ๋‹ค. ๋”ฐ

๋ผ์„œ ๊ธฐ๋ณธ์ ์ธ ํœจ ์„ฑ๋Šฅ์˜ ๊ตฌ๋ช…๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ์‚ฌ์šฉ์„ฑ์— ๋Œ€

ํ•œ ์—ฐ๊ตฌ๋„ ๋งค์šฐ ์ค‘์š”ํ•˜๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ดํ˜•

GFRP rebar๋กœ ํœจ ๋ณด๊ฐ•๋œ ๋ณด์˜ ๋‹จ์ ์ด ํฐ ์ฒ˜์ง๋Ÿ‰์„ ์˜ˆ์ธก

ํ•  ์ˆ˜ ์žˆ๋Š” ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹์„ ์ œ์‹œํ•˜์˜€์œผ๋ฉฐ

๊ฒฐ๋ก ์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

1) ๋ณธ ์—ฐ๊ตฌ์—์„œ ๊ฐœ๋ฐœ๋œ ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ• ์ฝ˜ํฌ

๋ฆฌํŠธ ๋ณด ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•ด ๊ธฐ์กด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ

์ œ์•ˆ์‹๋“ค๊ณผ ๋น„๊ต ๋ถ„์„ํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ ๊ธฐ์กด์˜ ์œ 

ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹์€ ๊ท ์—ด๋ชจ๋ฉ˜ํŠธ ์ดํ›„ ๊ทนํ•œ

๋ชจ๋ฉ˜ํŠธ์˜ 50% ์ˆ˜์ค€๊นŒ์ง€์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ๋Š” ๋น„

๊ต์  ์ •ํ™•ํžˆ ์˜ˆ์ƒํ•  ์ˆ˜ ์žˆ์—ˆ์œผ๋‚˜, ์ดํ›„์—๋Š” ์‹ค์ œ ์œ 

ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ๋ณด๋‹ค ๋‹ค์†Œ ๋†’์€ ๊ฐ’์„ ๋‚˜ํƒ€๋ƒ„์œผ๋กœ

์จ ์ตœ์ข… ํŒŒ๊ดด์‹œ๊นŒ์ง€์˜ ์ฒ˜์ง๋Ÿ‰์„ ๊ณผ์†Œํ‰๊ฐ€ํ•˜๋Š” ๊ฒฝํ–ฅ

์ด ์žˆ๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ๋‹ค.

2) ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜ ํ™˜์‚ฐ๋น„๋ฅผ ์ ์šฉ ๋ณด๊ฐ•๋น„๋ฅผ

์‚ฌ์šฉํ•œ Toutanji et al.9)์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ

์‹์„ ๋ฐ”ํƒ•์œผ๋กœ ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ

๋ณด์— ๋Œ€ํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ์‹์„ ๋„์ถœํ•˜์˜€

์œผ๋ฉฐ, ์ด๋ฅผ ์ ์šฉํ•˜์—ฌ ๊ฐ ์‹œํ—˜์ฒด์˜ ์‹œํ—˜ ๋ฐ์ดํ„ฐ์™€ ๋น„

๊ต ๋ถ„์„์„ ํ†ตํ•˜์—ฌ ๊ธฐ์กด์‹์— ๋น„ํ•ด ์ตœ์ข… ํŒŒ๊ดด์‹œ๊นŒ์ง€

EFRP

Es

------------ฯFRP 0.025 Ie,<Mcr

Ma

--------โŽ โŽ โŽ› โŽž

613ฯ

FRPEFRP

Es

-------------------------------โ€“

Ig =

1Mcr

Ma

--------โŽ โŽ โŽ› โŽž

613ฯ

FRPEFRP

Es

-------------------------------โ€“ Mg

10Mcr

----------------โŽ โŽ โŽ› โŽž 4+

โŽ โŽ โŽœ โŽŸโŽ› โŽž

โ€“โŽ โŽ โŽœ โŽŸโŽ› โŽž

Icrโ‹…+

EFRP

Es

------------ฯFRP 0.025 Ie,โ‰ฅMcr

Ma

--------โŽ โŽ โŽ› โŽž 3Ig 1

Mcr

Ma

--------โŽ โŽ โŽ› โŽž 3โ€“โŽ โŽ 

โŽ› โŽž Icrโ‹…+=

Fig. 10 The evaluation of the deflection by using the suggesting

equation for FSR2 specimen

Fig. 11 The evaluation of the deflection by using the suggesting

equation for FSR3 specimen

Fig. 12 The evaluation of the deflection by using the suggesting

equation for FSR4 specimen

Page 7: New Suggestion of Effective Moment of Inertia for Beams

์ดํ˜• GFRP Rebar๋กœ ๋ณด๊ฐ•๋œ ๋ณด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹ ์ œ์•ˆโ”‚191

์˜ ํ•˜์ค‘-์ฒ˜์ง๊ด€๊ณ„๋ฅผ ๋น„๊ต์  ์ •ํ™•ํžˆ ์˜ˆ์ธกํ•  ์ˆ˜ ์žˆ๋Š”

๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

3) ์ถ”ํ›„ ์ถ”๊ฐ€์ ์ธ ์‹คํ—˜ ๋ฐ ํ•ด์„์  ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•˜์—ฌ ๋‹ค์–‘

ํ•œ ํŠน์„ฑ์„ ๊ฐ–๋Š” ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌ

ํŠธ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ์„ค๊ณ„ยทํ•ด์„์‹์˜ ์ ์šฉ ๋ฐ ๊ฐœ๋ฐœ์ด

ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

์ฐธ๊ณ ๋ฌธํ—Œ

1. ์‹ฌ์ข…์„ฑ, ๊ณฝ๊ณ„ํ™˜, ๋ฐ•์„๊ท , ๊น€์žฅํ˜ธ, โ€œHybrid FRP Rod๋ฅผ ํ™œ

์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ ๋ชจ๋‹ˆํ„ฐ๋ง ์‹œ์Šคํ…œ ๊ฐœ๋ฐœโ€, ์‚ฐํ•™์—ฐ03

์—ฐ๊ตฌ๋ณด๊ณ ์„œ, ๊ฑด์„ค๊ตํ†ต๊ธฐ์ˆ ํ‰๊ฐ€์›, 2006, pp.1~303.

2. ์ด์ฐฝ์ˆ˜, ์œค์ธ์„, โ€œ์„œ์šธ์‹œ๋‚ด ์œ„์น˜ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ณ ๊ฐ€์ฐจ๋„์˜

๋‚ด๊ตฌ์„ฑ๋Šฅ ์กฐ์‚ฌ ๋ฐ ํ‰๊ฐ€โ€, ํ•œ๊ตญ๋ฐฉ์žฌํ•™ํšŒ๋…ผ๋ฌธ์ง‘, l2๊ถŒ, 1ํ˜ธ,

2002, pp.143~152.

3. Al-Salloum, Y. A., Alsayed, S. H., Almusallam, T. H., and

Amjad, M. A., โ€œEvaluation of Service Load Deflection for

Beams Reinforced by GFRP Barsโ€, Proceedings of the Sec-

ond International Conference on Use of Advanced Com-

posite Materials in Bridges and Structures, ACMBSII,

Montral, Quebec, Canada, 1996, pp.165~172.

4. ACI 318R-05, Building Code Requirements for Structural Con-

crete and Commentary, ACI Committee 318, 2005, pp.95~108.

5. ACI 440.1R-03, Guide for the Design and Construction of

Concrete Reinforced with FRP Bars, ACI Committee 440,

2003, pp.17~22.

6. Benmokrane, B., Chaallal, O., and Masmoudi, R., โ€œFlexural

Response of Concrete Beams Reinforced with FRP Rein-

forcing Barsโ€, ACI Structural Journal, Vol.92, No.2, 1996,

pp.46~55.

7. Branson, D. E., Deformation of Concrete Structures,

McGraw-Hill, New York, 1977, pp.1~546.

8. Moon, Do-Young, Bond Behavior of Newly Developed

Deformed GFRP Bars, Ph.D Thesis, Hanyang University,

2006, pp.1~224.

9. Houssam, A. Toutanji, H. A. , and Saffi, M., โ€œFlexural Behav-

iour of Concrete Beams Reinforced with Glass Fiber-Rein-

forced Polymer(GFRP) Barsโ€, ACI Structural Jounal, Vol.97,

No.5, 2000, pp.712~719.

10. ISIS Canada, Design Manual Stregthening Reinforced Con-

crete Structures with Externally-Bonded Fibre Reinforced

Polymer, ISIS Canada, 2001.

11. Larralde, J., Fiber Glass Reinforced Plastic Rebars in Lieu

of Steel Rebars, TRB Annual Meeting, Task Force A2C510,

Structural, Application of Fiber Reinforced Concrete, 1988.

12. Nawy, E. G., โ€œFiberglass Reinforced Concrete Slabs and

Beamsโ€, Jounal of Structural Division, ASCE, Vol.103,

1977, pp.421~404.

13. Yost, J. H., Fiber Reinforced Plstic Grids for Structural

Reinforcement of Concrete Beams, Ph.D thesis, University

of New Hampshire, USA, 1983.

์š” ์•ฝ ์ตœ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ ์—ดํ™”์™€ ๊ฐ™์€ ๋ฌธ์ œ๋ฅผ ๊ทผ๋ณธ์ ์œผ๋กœ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•ด ๊ณ ๋‚ด๊ตฌ์„ฑ์„ ๋ณด์œ ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์˜ ์žฅ์ˆ˜๋ช…

ํ™”์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ํ™œ๋ฐœํžˆ ์ง„ํ–‰๋˜๊ณ  ์žˆ๋Š” ๊ฐ€์šด๋ฐ, ์‹ ์„ค ๊ตฌ์กฐ๋ฌผ๋กœ์˜ ์ฒ ๊ทผ๋Œ€์ฒด FRP rebar๋ฅผ ์ ์šฉํ•œ ๊ณ ๋‚ด๊ตฌ์„ฑ ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ

์กฐ๋ฌผ์— ๋Œ€ํ•œ ์—ฐ๊ตฌยท๊ฐœ๋ฐœ ๋ฐ ํ™œ์šฉ์ด ์ ์ฐจ ์ฆ๊ฐ€๋˜๋Š” ์ถ”์„ธ์ด๋‹ค. ์ด์— ๋Œ€ํ•ด ์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์˜ ๊ฒฝ์ œ์ ์ธ ์ธก๋ฉด์—์„œ ์ ์šฉ ๊ฐ€

๋Šฅํ•œ FRP rebar๋กœ์„œ๋Š” GFRP rebar๊ฐ€ ์ฃผ๋ชฉ์„ ๋ฐ›๊ณ  ์žˆ์œผ๋ฉฐ ๊ทธ ์‚ฌ์šฉ์„ฑ ๋˜ํ•œ ์ฆ๋Œ€๋˜๊ณ  ์žˆ๋‹ค. ํ•˜์ง€๋งŒ GFRP rebar๋กœ ๋ณด๊ฐ•๋œ

์ฝ˜ํฌ๋ฆฌํŠธ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ํœจ๋ชจ๋ฉ˜ํŠธ ์„ฑ๋Šฅ์€ ์ด๋ฏธ ๊ทธ ์šฐ์ˆ˜์„ฑ์ด ๊ตฌ๋ช…๋˜์–ด ์žˆ์œผ๋‚˜ GFRP์˜ ๋‹จ์  ์ค‘ ํ•˜๋‚˜์ธ ์ฒ˜์ง์— ๋Œ€ํ•œ ์‚ฌ์šฉ

์„ฑ ์ธก๋ฉด์€ ๊ฐœ์„ ๋˜์–ด์•ผ ํ•  ์ ์œผ๋กœ ์ง€์ ๋˜๊ณ  ์žˆ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐœ๋ฐœ๋œ ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ ๋ณด ๊ตฌ์กฐ๋ฌผ์˜

์ฒ˜์ง ๊ฑฐ๋™ ์˜ˆ์ธก์„ ์œ„ํ•ด ๊ธฐ์กด์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ์‹๋“ค๊ณผ ๋น„๊ต ๋ถ„์„์„ ์‹ค์‹œํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ ๊ธฐ์กด์˜ ์œ ํšจ๋‹จ๋ฉด์ด

์ฐจ๋ชจ๋ฉ˜ํŠธ ์‚ฐ์ •์‹์€ ๊ท ์—ด๋ชจ๋ฉ˜ํŠธ ์ดํ›„ ๊ทนํ•œ๋ชจ๋ฉ˜ํŠธ์˜ 50% ์ˆ˜์ค€๊นŒ์ง€์˜ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ๋Š” ๋น„๊ต์  ์ •ํ™•ํžˆ ์˜ˆ์ƒํ•  ์ˆ˜ ์žˆ

์—ˆ์œผ๋‚˜ ์ดํ›„์—๋Š” ์‹ค์ œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ๋ณด๋‹ค ๋‹ค์†Œ ๋†’์€ ๊ฐ’์„ ๋‚˜ํƒ€๋ƒ„์œผ๋กœ์จ ์ตœ์ข… ํŒŒ๊ดด์‹œ๊นŒ์ง€์˜ ์ฒ˜์ง๋Ÿ‰์„ ๊ณผ์†Œํ‰๊ฐ€ํ•˜

๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜ ํ™˜์‚ฐ๋น„๋ฅผ ์ ์šฉํ•œ ๋ณด๊ฐ•๋น„๋ฅผ ์‚ฌ์šฉํ•œ Toutanji et al. (2000)์˜ ์œ ํšจ

๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ์‹์„ ๋ฐ”ํƒ•์œผ๋กœ ์ดํ˜• GFRP rebar๋กœ ๋ณด๊ฐ•๋œ ์ฝ˜ํฌ๋ฆฌํŠธ๋ณด์— ๋Œ€ํ•œ ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ ์ œ์•ˆ์‹์„ ๋„์ถœ

ํ•˜์˜€์œผ๋ฉฐ, ๊ทธ ๊ฒฐ๊ณผ ์ œ์•ˆ๋œ ์‹์„ ์ ์šฉํ•˜์—ฌ ๊ฐ ์‹œํ—˜์ฒด์˜ ์‹œํ—˜๋ฐ์ดํ„ฐ์™€ ๋น„๊ต ๋ถ„์„์„ ํ†ตํ•˜์—ฌ ์ตœ์ข… ํŒŒ๊ดด์‹œ๊นŒ์ง€์˜ ํ•˜์ค‘-์ฒ˜์ง

๊ด€๊ณ„๋ฅผ ๋น„๊ต์  ์ •ํ™•ํžˆ ์˜ˆ์ธกํ•  ์ˆ˜ ์žˆ๋Š” ๊ฒƒ์œผ๋กœ ๋ถ„์„๋˜์—ˆ๋‹ค.

ํ•ต์‹ฌ์šฉ์–ด : ์ดํ˜• GFRP rebar, ๋‚ด๊ตฌ์„ฑ, ์œ ํšจ๋‹จ๋ฉด์ด์ฐจ๋ชจ๋ฉ˜ํŠธ, ์‚ฌ์šฉ์„ฑ