15.529~536(11-039).fm

Size: px

Start display at page:

Download "15.529~536(11-039).fm"

수빈 전
5 years ago
Views:

1 Journal of the Korea Concrete Institute Vol. 23, o. 4, pp. 529~536, August, 211 GGGGG z e f ü w x sƒ y 1) *Á 2) 1) û w» w m œw Experimental Verification on the Structural Safety of Cantilever Beam Connected with Post-installed Adhesive Anchor Bolts Hong-Seob Oh 1) * and Sung-Rak Park 2) 1) Dept. of Civil Engineering, Gyeongnam ational University of Science and Technology, Jinju , Korea ABSTRACT Recently, there has been a growing interest in expanded sidewalks for existing bridges. The cantilever beam system applied to expanded sidewalks for existing bridges are connected with the concrete structure by adhesive anchor bolts. However, the extended sidewalks are currently constructed without standardized regulations, which lead to excessive design of the beam spacing and installation and the construction difficulties due to the excessive over-weight. Moreover, there is only limited analysis and experiment data on the post-installed adhesive anchor bolts, so the excessive number of bolts is used for the connection. This paper deals with a method to increase the effectiveness of beam sections and anchor bolts geometry for expanded sidewalk of existing bridge. The study results showed that the failure of cantilever beam connected by adhesive anchor bolts was dominated by bond failure of interface between concrete and bolt. Also, the results indicated the possibilities of improving serviceability as well as safety of the sidewalks by changing of beam section and prestressing the bolts. Keywords : cantilever beam, post installed adhesive anchor bolt, prestressing, expanded sidewalk 1. œ w ³ ƒ ù s w š x k. w ƒ Fig. 1 œ w w k w y œw ƒ ã ƒwš.» y w œ Fig. 2(a) ƒ y wš x v ew w ù, Fig. 2(b) z e f p w ep š w š. ƒ w œ wš f w œ» ƒw ƒ w. w Fig. 1 z e f p w gj p ep *Corresponding author opera69@chol.com Received April 13, 211, Revised May 26, 211, Accepted May 26, X by Korea Concrete Institute w œ rwù f ep x w ƒ w. y z e f w w ww f f w w š ƒ v ù, ¾ z e f w ƒ wš f e v w ƒ ü w š» x x w œ š. z e f gj p ep { sƒ x mw f p ep x z wš w, w z ww f p e x wš w. 2. x gj p ü Fig. 3 x ƒ š Hx (A type) x (B type) w q w x ew. A type x 1/2¾ ew 529

Fig. 1 Expended sidewalk for existing bridge Fig. 2 Typical construction methods for expending a sidewalk of bridge, B type ew. A type B type ep x e w ƒƒ 12 z e f g j p w.

¼ 5%ƒ D29 w mj w v p w. y w ü» 1) w, Table 1 w. ü SS4 Fig. 3 Cantilever beam section and the geometry of inserted anchor bolts (unti: mm) Hx (A type) w 2. mm 3. mm 1m ew w, š w gj p ù ƒƒ 3% w w w. 3. x z» gj p y w ü ƒ Table 1 Design moments of cantilever beams A type (2 m) B type (3 m) Live load w l 5k/m w l 5k/m Self weight w d1 1.

2 Fig. 1 Expended sidewalk for existing bridge Fig. 2 Typical construction methods for expending a sidewalk of bridge, B type ew. A type B type ep x e w ƒƒ 12 z e f g j p w. ü w w f mw gj p ü w x wš, f w w v p w. ü q f w q, x q f v p ü q xk ùkù w š ƒ v. w w f š, ü w w C type w x ww. z e ü ¼ w w ü w ƒ w. w» w D type C type ü x ü f ƒ ewš v p w wš w jš w. ¼ 5%ƒ D29 w mj w v p w. y w ü» 1) w, Table 1 w. ü SS4 Fig. 3 Cantilever beam section and the geometry of inserted anchor bolts (unti: mm) Hx (A type) w 2. mm 3. mm 1m ew w, š w gj p ù ƒƒ 3% w w w. 3. x z» gj p y w ü ƒ Table 1 Design moments of cantilever beams A type (2 m) B type (3 m) Live load w l 5k/m w l 5k/m Self weight w d1 1.2k/m w d1.4k/m Dead load Pavement w d2 8.1k/m Guardrail P v 1.3k Design moment M u 56k. m M u 117k. m Fig. 4 The shape of cantilever beam connected with concrete block using anchor bolts (unit: mm) 53 w gj pwz 23«4y (211)

Table 2 Dimension of anchor bolt dimension Diameter (d ) Embedment depth h ef (mm) Gross sectional area A D (mm 2 ) Effective sectional area A e (mm 2 ) Chemical adhesive Tension Compressive strength

3 Table 2 Dimension of anchor bolt dimension Diameter (d ) Embedment depth h ef (mm) Gross sectional area A D (mm 2 ) Effective sectional area A e (mm 2 ) Chemical adhesive Tension Compressive strength strength (k) (k) M Table 3 Test variable for anchored cantilever beams Concrete compressive strength Section type f ck 18MPa f ck 27MPa f ck 35MPa A-2m B-2m B-3m C-2m C-3m D-3m gj p f w Fig. 4 x gj p w ü f w. gj p f Table 2 ùkü, e» z e w gj p l 1 mm w ü ƒ e w. gj p ƒƒ 18 MPa, 27 MPa 35 MPa w, j» f p ¾ ü š w 1,2 1,2 6 mm w. x Table 3 Fig. 3 w ƒ x w ww. f ü x ƒ gj p w š, w x 7 12 z e f ew. f e (1) y œ, (2) œ, (3) f f v p e, (4) fy f v p œ f f œ w. f gj p w f f f M24 p w w 23.7 k, { p m. x Fig. 5 1, k d l w, w w w š w s w w H-beam ƒ w. w ƒ w, w.11 mm/sec w. ü w w x w» w g j p 5 k w w. w ü ƒ e w ü lv w. x LVDT w f v p w, s d w f p z d wš w, ü š, ü d w. w x ew f v p ü q q wš w. f ü x e Fig üw 4. x Table 4 x w p w š w» 1,2) p w. x Hx w ü p w q, B type 2m w p 2 w ùkû ù, 3m gj p 18 MPa 27 MPa x p w wš q ùkû. x w w x w q q. f p š, x w C type, x w B type w ƒ 3~7% w, üw w w üw y w q. C type v p w D type gj p w ùkü ù, x f p q w» q Table 4 Load carrying capacity of specimens Fig. 5 Test set-up for the structured behavior test Section type Experimental ultimate moment capacity 18 MPa (k. m) 27 MPa (k. m) 35 MPa (k. m) Design moment (k. m) A-2 m X B-2 m B-3 m C-2 m X C-3 m D-3 m X 116 z e f ü w x sƒ 531

4 Fig. 6 Moment-displacement relationship of anchored cantilever beams 괴되는 형태를 나타내었다. 따라서 긴장재 정착단을 보강 할 경우에는 강도가 보다 증가할 수 있을 것으로 판단된다. Fig. 6에는 실험체별 모멘트-변위 선도와 각 실험체별 최대 내하력을 3등분하여 내민보의 전체 변위 형상을 표 시하였다. 전체적으로 A type의 경우가 전체적인 강성이 큰 것으로 나타났으며, B type의 경우는 초기 강성은 C type보다 크게 나타났으나 최대 모멘트 후 하중이 급격 히 감소하는 형태를 나타내었다. D type의 경우에는 긴 장재 정착단의 볼트 용접부가 파괴된 후 하중이 급격히 감소하였다가 다시 증가한 후 파괴되는 형태를 나타내 었으나, 변위는 C type보다 감소하여 사용 상태에서의 강 성 증대 효과는 기대할 수 있는 것으로 판단된다. D type 실험체의 경우 긴장용 강봉 끝단에 볼트를 현장 용접하 여 예상 강도보다 낮은 상태에서 파괴된 것으로 판단되 며, 강봉에 직접 정착단을 설치할 경우에는 강도가 실험 결과보다 향상될 것으로 판단된다. 실험체 전체 변위 형 상의 경우, 단면 강성이 큰 A type과 수직 보강재가 전 지간에 설치된 B type의 경우는 최대 모멘트 도달시까지 내민보의 전체 변형은 선형적인데 비해 수직 보강재가 지간의 1/2만 설치된 C type과 D type의 경우에는 고정 단부터 지간 중앙부까지의 기울기보다 지간 중앙부부터 자유단까지의 변형의 기울기가 큰 것으로 나타나 수직 보강재에 의한 변형 제어 효과가 큰 것으로 분석되었다. 4.2 파괴 형상에 따른 분석 앵커 연결된 내민보의 전형적인 파괴 형태와 시험체별 532 한국콘크리트학회 논문집 제23권 제4호 (211) Fig. 7 Typical failure modes of specimens 단계별 파괴 형태는 Fig. 7과 Table 5에 정리하였다. 모 든 실험체의 초기 파괴 형태는 부착식 앵커의 인발에 의 하여 시작되는 것으로 관찰되었으며, A type과 C, D type 의 경우에는 콘크리트 파괴에 발생한 반면 B type의 경 우에는 수직 보강재의 좌굴에 의한 파괴가 지배적인 것 으로 나타났다. 지간 2 m의 A type 실험체에서 콘크리트 가 35 MPa로 강도가 높았던 실험체에서는 앵커 플레이 트와 내민보의 용접부가 인장 파괴되는 현상을 나타내었 다. C type 2 m의 경우 콘크리트 강도 27 MPa 실험체에 서 수직 보강재가 끝나는 지간 중앙부에서 강관이 보강

Table 5 Failure propagation steps of cantilever beam Section type Concrete strength (MPa) Failure mode process A-2m B-2m B-3m C-2m C-3m w z w w w, D type ¼ q w w üw ƒ C type gj p q x ùk ü. 4.

5 Table 5 Failure propagation steps of cantilever beam Section type Concrete strength (MPa) Failure mode process A-2m B-2m B-3m C-2m C-3m w z w w w, D type ¼ q w w üw ƒ C type gj p q x ùk ü. 4.3 m 27 BF CB WP 35 BF WP 18 BF LB 27 BF LB 35 BF LB 18 BF CB LB 27 BF LB 35 BF LB 27 BF SF 35 BF SF 18 BF CB 27 BF CB 35 BF CB 18 BF WF CB D-3m 27 BF WF CB BF-adhesve bond failure, CB-concrete breakout, SF-yield of steel beam, LB-local buckling, WP-failure at welding point of anchor plate, WF-fracture at welding point of anchoring bolt for prestressing w» 1) e2) ww x L/3. f ü x x mw w mw Table 6 w. w ƒ ü 1m w yw» LVDT w x w. m ü 1m w x Table 6 Deflection stability Span (m) 2 Type A B C Concrete strength (MPa) Deflection (mm) Live load (km) Allowable deflection (mm) mw w y w q, ü 1.5~2 m k w w q. 5. z e f p üw m 5.1 z e f p w m y ü gj p d z e f p w üw. ü w w z e f p w, ü w w f w mƒ v. z e f p w w q f p,, gj p w q, gj p v w, 5-12) Fig. 8 q xkƒ w. ƒ q x k w q w x w Fastener steel strength f. s na e f uta () (1)», n : f f A e : f z (mm) f uta : f» (MPa), f uta 1.9f y 862 MPa ù w Concrete breakout strength (tension) f f s cr, w». ü f 3) 4) ACI h ef 6) w. Lehr 16d 8) w š, Eligehausen et al. [ 14.7 ] w. 9) d τ/1 Eligehausen et al w 2 d ( τ u /1) ƒ f p ww 2/3 š q w w. w gj p q Fig. 9 š, f œe gj p Fig. 8 Potential failure modes of bonded anchors z e f ü w x sƒ 533

6 x g wù, M2 w x x y w» ¼ (h ef ) p (d) 9) š w M2 p x 8MPa q w M24 p 7MPa ƒ w. f p w. Fig. 9 Unheaded fastener group influence area uc A c, A c,, uc ψ g, ψ ec () (2), f» gj p q cu 13.5 f ck ( h ef ) 1.5 () (3) w 2 A : f gj p q n (mm 2 c, S cr, ) A c : f gj p q n (mm 2 ) ψ ec e /s cr, 1, 2 c 1 s cr, 2 d ( τ u /1) cr, ψ g, u A c, ψ g, ψ ec A c, () (4), f p f» u τ π d h ef w ψ g, s ψ g, + s cr, ψ g, n α, u () (5) ( 1 ψ g, ) h f α.7 ( 1 τ u /τ u, max ).5 τ u, max ( )/d ef ck Fastener strength in shear f. V s n.6a e f uta () (6) Adhesive bond strength f (τ) ASTM E488 13) w Pryout strength f œe v. Table 7 Comparison of failure strength of bonded anchor bolts in experimental and theoretical strength A-2m B-2m B-3m C-2m C-3m D-3m Concrete strength (MPa) Test (k) Failure mode Theory Adhesive bond strength Concrete breakout strength Fastener steel strength BF WP BF BF WP BF BF LB BF BF LB BF BF LB BF BF LB BF BF LB BF BF LB BF BF SF BF BF BF BF BF CB BF BF CB BF BF CB BF BF WF BF BF WF BF Test Theory 534 w gj pwz 23«4y (211)

7 V CP K cp uc», k cp. h ef <65mm k cp 1. h ef >65mm k cp 2. () (7) f m ü x 4 f p 4 w q sƒw x wì Table 7 w. f p q w q ù, q ƒ w» Table 7 q w w w. w w ƒ ùkü adhesive bond strength x w. 5.2 x f ü x z e f p Table 7 ùkü, t ù kü () f p w 4 p w w p» y w. x w w x w f p adhesive bond failure w y w. x q x y w» w x» adhesive bond failure x z q t ùkü q x x ƒ w k w z q ùkû. x w w x w w ù y w, w f p w f p (τ )ƒ de w wù f p w f ü sƒ» (τ ) x mw w» q. ù w q ü w x q xk adhesive bond failure z f p concrete breakout ù w ùkû. 6. ³ y ƒ w f ü w x w, w. 1) f, œ y w f w ù, A type f ƒ ùkû» C type xk f w z q. 2) f p pƒ w C type d f p yw œ œ z y k q. 3) ùkù f ü ¼ üw w w y w» w q. 4) w w š w v p 5% w ¼ w q y w w q. 21 û w» w w œ» w. š x 1. m,», 25, 51 pp. 2. mw,» e, 29, 196 pp. 3. š, ½¼, ½ z, ½ z, ½ x, ûy,,,,, w, gj p f, w gj pwz, 21, 338 pp. 4. ACI Committee 318, Building Code Requirements for Structural Concrete and Commentary (ACI318M-5), American Concrete Institute, 25, 443 pp. 5. ½ x, ½¼,,,,, f» (ACI318-5), w gj pwz w z 26, pp. 53~ Lehr, R., Tragverhalten von Verbunddübeln im Ungerissenen unter Zentrischer Belastung im Ungerissenen Beton- Gruppenbefestigungen und Befestigungen am Bauteilrand, Doctoral Thesis, University of Stuttgart, Stuttgart, Germany, 23, 32 pp. 7. Cook, R. A., Kunz, J., Funchs, W., and Konz, R. C., Behavior and Design of Single Adhesive Anchors under Tensile Load in Uncracked Concrete, ACI Structural Journal, Vol. 95, o. 1, 1998, pp Eligehausen R., Cook R., and Appl, J., Behavior and Design of Adhesive Bonded Anchors, ACI Structural Journal, Vol. 13, o. 6, 26, pp Eligehausen, R., Mallee, R., and Silva, F. J., Anchorage in Concrete Construction, Ernst & Sohn, 26, 378 pp. 1., y,», x, f p w x, wm wz, 26«, 3 z e f ü w x sƒ 535

8 y, 26, pp. 555~ ½ x,,,, gj p f ü x l, gj pwz, 17«, 5y, 25, pp. 29~ Matthew Miltenberger, P. E., Capacity Design of Grouted Anchors, SMiRT 16, Wasington DC, 21, pp. 179~ ASTM E488, Standard Test Methods for Strength of Anchors in Concrete and Masonry Elements, ASTM, 1996, 21 pp. ü y w š š. y ü f p w wš. ù x š ü yw» k e š w w œ wš. w z e f p w x w e» v w f p jš. f ü sƒ x mw» ü yw z y wš, v w f p» wš w. x ü q f q ùkû, d f g j ƒ. w ü x y jš v p w k w k ùkû. w : ü, z e f p, v p, y 536 w gj pwz 23«4y (211)

14.531~539(08-037).fm

14.531~539(08-037).fm G Journal of the Korea Concrete Institute Vol. 20, No. 4, pp. 531~539, August, 2008 š x y w m š gj p { sƒ z 1) * 1) w w Evaluation of Flexural Strength for Normal and High Strength Concrete with Hooked