고성능 리모델링기술을 활용한 성능설계기반 기존 철근콘크리트 건축물의 내진성능 평가 및 개선

하기주,이동렬,김창석 대한건축학회지회연합회 2024 대한건축학회연합논문집 Vol.26 No.3

In this study, specimens, designed by reinforced concrete frame using the advanced seismic frame remodelling technology, were constructed and tested to improve the seismic performance of reinforced concrete buildings subjected to earthquake-tpye loadings, Six-story existing reinforced concrete buildings, applying the advanced frame remodelling technology were carried out to evaluate the seismic performance based on performance design. In the evaluation of seismic performance of the existing reinforced concrete buildings using the advanced frame remodelling technology by the performance based design, as a result of nonlinear static analysis of reinforced concrete structures, the story drift angle in the x- direction showed up to 16% reduction when applying the advanced seismic remodelling technology(RFXB-F, RFAR) compared to before reinforcement.

섬유시트와 매입형 CFRP Rod를 보강한 R/C 외부 보-기둥 접합부의 내진성능 평가 및 개선

하기주,하영주,강현욱 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회 논문집 Vol.19 No.2

본 연구에서는 기존 철근콘크리트 구조물 보-기둥 접합부의 내진성능의 개선을 위해 보-기둥 접합부 영역을 FRP보강재 (탄소섬유시트, 아라미드섬유시트, 매입형 CFRP Rod)를 사용하여 보강한 후 내진성능을 평가하였다. 총 7개의 실험체를 제작하고 실험을 수행하여 내진성능을 평가하였으며, 본 연구의 실험결과를 근거로 다음과 같은 결론을 얻었다. 기존 철근콘크리트 보-기둥 접합부의 접합부 영역을 보강한 결과, 초기 재하시 접합부 영역의 균열억제 효과와 재하 전 과정을 통하여보강재의 구속효과로 인하여 균열억제 효과가 커서 안정적인 파괴형태 및 내력향상 효과를 나타내었다. 매입형 CFRP Rod와 탄소섬유시트를 활용한 R/C 외부 보-기둥 접합부 실험체 LBCJ-CRUS는 표준실험체 LBCJ와 비교하여 변위연성4, 7에서 각각 최대내력은 1.54배, 에너지소산능력은 2.36배 증가하였다. 그리고 실험체 LBCJ-CS, LBCJ-AF시리즈는 변위연성 7에서 표준실험체 LBCJ 보다 에너지소산능력이 각각 2.04~2.34, 1.63~3.02배 증가하였다. In this study, experimental research was carried out to evaluate and improve the seismic performance of reinforced concrete beam-column joint regions using strengthening materials (CFRP sheet, AFRP sheet, embedded CFRP rod) in existing reinforced concrete structure. Therefore it was constructed and tested seven specimens retrofitting the beam-column joint regions using such retrofitting materials. Specimens, designed by retrofitting the beam-column joint regions of existing reinforced concrete structure, were showed the stable failure mode and increase of load-carrying capacity due to the effect of crack control at the times of initial loading and confinement of retrofitting materials during testing. Specimens LBCJ-CRUS, designed by the retrofitting of CFRP Rod and CFRP Sheet in reinforecd beam-column joint regions were increased its maximum load carrying capacity by 1.54 times and its energy dissipation capacity by 2.36 times in comparison with standard specimen LBCJ for a displacement ductility of 4 and 7. And Specimens LBCJ-CS, LBCJ-AF series were increased its energy dissipation capacity each by 2.04~2.34, 1.63~3.02 times in comparison with standard specimen LBCJ for a displacement ductility of 7.

나트륨계 알칼리 활성화제를 사용한 친환경 알카리활성 슬래그 섬유보강콘크리트 보의 휨성능 평가

하기주,이동렬,하재훈 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회 논문집 Vol.19 No.2

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc. 이 연구에서는 산업부산물인 알카리활성 슬래그와 알칼리 활성화제 (물유리, 수산화나트륨)에 강섬유를 사용하였으며, 이를 철근콘크리트 보에 적용하여 휨성능 평가를 하였다. 주요변수는 알칼리 활성화제의 혼입비율 및 강섬유를 혼입으로 총 8개의 실험체를 제작하였으며, 재료 및 구조성능 평가를 위한 실험을 수행한 결과 다음과 같은 결론을 얻었다. 친환경 알카리활성 슬래그 섬유보강콘크리트를 사용한 철근콘크리트 보는 전반적으로 휨 또는 휨-전단에 의하여 파괴되었다. 그리고 수산화나트륨의 몰 증가와 강섬유를 보강한 결과 최대내력이15.8~25.9% 증가한 값이 나타났으며, 연성 또한 높게 나타났다. 친환경 알카리활성 슬래그 섬유보강콘크리트는 기존의 콘크리트를 대체할수 있는 기초연구로서 향후 건설소재 및 재료분야에 활용할 수 있을 것으로 사료되며, 이러한 특성을 바탕으로 콘크리트 2차 제품 생산과구조부재를 PC화하여 활용할 경우 생산성 향상, 공기단축 등 효율이 상승될 것으로 보인다.

매입형 CFRP Rod와 CFRP시트를 활용한 RC 외부 보-기둥 접합부의 내진성능 평가 및 개선

하기주,강현욱 한국구조물진단유지관리공학회 2014 한국구조물진단유지관리공학회 논문집 Vol.18 No.3

In this study, experimental research was carried out to evaluate and improve the seismic performance of reinforced concrete beam-column joint regions using strengthening materials (embedded CFRP rod and CFRP sheet) in existing reinforced concrete building. Therefore it was constructed and tested six specimens retrofitting the beam-column joint regions using such retrofitting materials. Specimens, designed by retrofitting the beam-column joint regions of existing reinforced concrete building, were showed the stable failure mode and increase of load-carrying capacity due to the effect of crack control at the times of initial loading and confinement of retrofitting materials during testing. Specimens RBCJ-SRC2, designed by the retrofitting of CFRP Rod and CFRP Sheet in reinforecd beam-column joint regions were increased its maximum load carrying capacity by 1.97 times and its energy dissipation capacity by 2.08 times in comparison with standard specimen RBCJ for a displacement ductility of 4 and 7. Also, specimens RBCJ-SRC2 were increased its maximum load carrying capacity by 1.09~1.11 times in comparison with specimen RBCJ-SR series. And Specimens RBCJ-CS, RBCJ-SR series, RBCJ-SRC2 were increased its energy dissipation capacity by 1.10~2.30 times in comparison with standard specimen RBCJ for a displacement ductility of 5, 6. 본 연구에서는 기존 철근콘크리트 건물의 보-기둥 접합부의 내진성능의 개선을 위해 보-기둥 접합부 영역을 FRP보강재(매입형 CFRP Rod, CFRP시트)를 사용하여 보강한 후 내진성능을 평가하였다. 총 6개의 실험체를 제작하고 실험을 수행하여 내진성능을 평가하였으며, 본 연구의 실험결과를 근거로 다음과 같은 결론을 얻었다. 기존 철근콘크리트 보-기둥 접합부의 접합부 영역을 보강한 결과, 초기 재하시 접합부 영역의 균열억제 효과와 재하 전 과정을 통하여 보강재의 구속효과로 인하여 균열억제 효과가 커서 안정적인 파괴형태 및 내력향상 효과를 나타내었다. 매입형 CFRP Rod와 CFRP시트를 활용한 RC 외부 보-기둥 접합부 실험체 RBCJ-SRC2는 표준실험체 RBCJ와 비교하여 변위연성4, 7에서 각각 최대 내력은 1.97배, 에너지소산능력은 2.08배 증가하였다. 또한, 실험체 RBCJ-SR시리즈와 비교하여 최대내력이 1.09~1.11배 증가하였다. 그리고 실험체 RBCJ-CS, RBCJ-SR시리즈, RBCJ-SRC2는 변위연성 5, 6에서 표준실험체 RBCJ 보다 에너지소산능력이 1.10~2.30배 증가하였다. 그리고 에너지소산능력은 변위연성 4에서 13.0~14.4% 증가하였다.

표면요철 매입형 FRP봉과 CFRP시트를 복합 보강한 철근콘크리트 보의 구조성능 평가

하기주,하영주 한국구조물진단유지관리공학회 2014 한국구조물진단유지관리공학회 논문집 Vol.18 No.4

본 연구에서는 기존 철근콘크리트 건축물의 구조성능 개선을 위하여 표면요철 매입형 FRP봉과 CFRP시트를 사용한 철근콘크리트 보의 구조성능을 평가하기 위하여 실험을 수행하였다. 표면요철 매입형 FRP봉의 사용량, CFRP시트 보강 유무에 따라 총 7개의 실험체를 제작하고 실험을 수행하여 구조성능을 평가하였으며, 본 연구의 실험결과를 근거로 다음과 같은 결론을 얻었다. 표면요철 매입형 FRP봉 보강 실험체 NER 시리즈의 경우, 표준실험체 NBS와 비교하여 12~46% 내력이 증가하였고, 표면요철 매입형 FRP봉과 CFRP시트를 복합 보강한 실험체 NERL 시리즈는 표준실험체 NBS보다 최대내력이 22~77% 증가하였다. 그리고 표면요철 매입형 FRP봉으로 보강된 실험체 NER 시리즈는 부착슬립, 피복분리 형태로 파괴되었으나, 표면요철 매입형 FRP봉과 CFRP시트을 복합 보강한 실험체 NERL 시리즈는 CFRP시트의 연속보강에 따른 콘크리트 구속효과 및 모재와 표면요철 매입형 FRP봉의 부착강도 증가로 인하여 부착슬립의 형태로 파괴되었다. In this study, experimental research was carried out to evaluate the structural performance of the reinforced concrete beam using hybrid retrofitting with two materials (groove and embedding FRP rod, CFRP sheet) in existing reinforced concrete buildings. Seven reinforced concrete beams, retrofitted groove and embedding FRP rod (NER series) and groove and embedding FRP rod with CFRP sheet (NERL series), and standard specimen (NBS) were constructed and tested under monotonic loading. Design parameters of test specimens are the amount of groove and embedding FRP rod and lapping CFRP sheet. Test results showed that the maximum load carrying capacity of specimens with groove and embedding FRP rod and groove and embedding FRP rod with CFRP sheet (NERL series) were increased the by 12~46% and 22~77% respectively in comparison with the standard specimen NBS. Test specimens NER series were failed with the adhesion slip and concrete cover separation. And test specimens NERL series were failed with the adhesion slip due to the confining effect of lapping CFRP sheet.

고강도 철근콘크리트 보-기둥 접합부의 내진성능 개선에 관한 실험적 연구

하기주,김진근,정란,Ha, Gee-Joo,Kim, Jin-Keun,Chung, Lan 한국콘크리트학회 1992 콘크리트학회지 Vol.4 No.1

With the increasing tendency to construct high rise reinforced concrete building~i, it is required to use high strength materIals, smaller member sections, and larger reinforcing bars, I t is generally recognized that under severe seismic loads beam column jomts may become more critical structural components than other structural elements. In a ductile momentresistmg reinforced concrete frame, the connection of bearncolumn must be capable of resistll1g the large lateral forces caused by seismic actions, The purpose of this experimental study is to evaluate and ll1vestigate the earthquake resistant perform ance of beam-colurrm subassemblies constructed with high-strength concrete cast by the concrete of com¬pressive strength of 700kg / cm2 subjected to reversed cyclic loadings. New approaches for moving the plastic hinging zone away from the column face and preventing the di¬agonal crack in the joint region are adopted to advance the earthquake-resistant performance of beam-column subassemblies using high-strengh concrete under severe earthquake-type loading. Exper¬imental results indicate that the modified new details which are introduced by intermediate reinforcement in the beam over a specific beam length adjacent to the joint are able to attain the stable hysteretic behavior and the enhancement of earthquake-resistant performance. Keywords: high strength concrete: beam-column Joints; seirnic loads(reversed cyclic loading) : earth¬quake-resistant performance; plastic hinge zone: diagonal crack: intermediate reinforce¬ment ; closed strirrup: hysteretic behavior: enhancement .

철근콘크리트 보-기둥 접합부의 내진성능 개선 보강 신기술

하기주 한국지진공학회 2004 한국지진공학회논문집 Vol.8 No.2

본 연구에서는 기존 철근콘크리트건물 보-기둥 접합부의 내진 성능을 개선하기 위하여 탄소섬유를 사용하여 구조물을 보강한 후 실험을 수행하였다. 이를 위하여 6개의 철근콘크리트 보-기둥 접합부를 제작하였으며, 지진하중과 같은 반복하중이 작용할 때 보강재료 및 보강영역 등을 변수로 하여 실험을 수행하여 각 보강변수에 따른 보강효과를 평가하였다. 본 실험을 통하여 구조물의 내진 성능 및 연성능력을 증진시킬 목적으로 새로운 보강재료(탄소섬유판, 탄소섬유봉, 탄소섬유쉬트)로 설계된 보강 실험체(RPC-CP2, RPC-CR, RJC-CP, RJC-CR)들은 내력증진은 물론이고 안정적인 이력거동을 확보할 수 있었다. In this study, experimental research was carried out to improve earthquake-resistant performance for the retrofitting of reinforced concrete beam-column joints using carbon fiber materials in existing reinforced concrete building. Six reinforced concrete beam-column joints were constructed and tested to evaluate the retrofitting effect of test variables, such as the retrofitting materials and retrofitting region(plastic hinge, beam-column joint) under load reversals. Test results show that retrofitting specimen(RPC-CP2, RPC-CR, RJC-CP, RJC-CR), using new materials(carbon fiber plate, carbon fiber rod and carbon fiber sheet), designed by the improvement of earthquake-resistant performance and ductility, attained more load-carrying capacity and stable hysteretic behavior.

고성능 리모델링기술을 활용한철근콘크리트 골조의 내진성능 평가 및 개선

하기주,이동렬,김창석 대한건축학회지회연합회 2024 대한건축학회연합논문집 Vol.26 No.2

Four reinforced concrete frame using advanced remodelling technology, which is designed by the conventional method, remodelling technology of ALC panel, X-type steel bracing system with and without steel frame in R/C frame, were tested under both vertical and cyclic loadings, Experimental programs were carried out to evaluate and improve the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, energy dissipation capacity, and crack propagation etc. under load reversals. All the specimens were modeled in one-third scale size. Based on the test results reported in this study, the following conclusions can be made. The maximum load-carrying capacity of specimens(RFAR, RFXB, RFXB-F) designed by the advanced remodelling technology for standard specimen(SRF) were increased 1.46~4.27 times in comparison with the standard specimen(SRF). Energy dissipation capacity of specimens designed by the improving of seismic performance were increased 2.14~4.72 times in comparison with the standard specimen(SRF).

고성능 배근상세를 활용한 고강도철근콘크리트 보-기둥 접합부 내진성능 평가 및 개선

하기주 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.5

In this dissertation, experimental research was carried out to study the hysteretic behavior of reinforced high-strength concrete beam-column joints designed by high performance techniques, such as application of high-strength concrete, reducing of joint regions damage, moving of beam plastic hinge, and advanced reinforcing detailings.Specimens(HJAI1, HJAI2, HJCI), designed by the development of earthquake-resistant performance, moving of beam plastic hinge, and new design approach, were attained the moving of beam plastic hinge and developed significantly earthquake-resistant performance of such joints. Especially, specimen HJCI, designed by the supplemental intermediate longitudinal reinforcement and the closed stirrup of confinement of concrete in beam near the joint was evaluated very excellent new design details of reinforced beam-column joints.Specimens(HJAI1, HJAI2, HJCI), designed by moving of beam plastic hinge and improvment of structural performance were sufficiently moved away 20㎝, 30㎝ from the column face respectively due to adding supplemental intermediate longitudinal reinforcement over a specific length 1.0d and 1.5d and application of closed stirrup.

철근콘크리트 보의 매입형 탄소섬유봉과 보강철물 보강에 따른 구조성능 평가

하기주,하영주 대한건축학회지회연합회 2013 대한건축학회지회연합회 학술발표대회논문집 Vol.2013 No.1