• Earthquakes and Structures
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• 제15권6호
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• pp.617-627
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• 2018

After earthquakes FRP sheets are often used for the rehabilitation of damaged Reinforced Concrete (RC) beamcolumn connections. Connections with minor to moderate damage are often dealt with by applying FRP sheets after a superficial repair of the cracks using resin paste or high strength mortar but without infusion of thin resin solution under pressure into the cracking system. This technique is usually adopted in these cases due to the fast and easy-to-apply procedure. The experimental investigation reported herein aims at evaluating the effectiveness of repairing the damaged beam-column connections using FRP sheets after a meticulous but superficial repair of their cracking system using resin paste. The investigation comprises experimental results of 10 full scale beam-column joint specimens; five original joints and the corresponding retrofitted ones. The repair technique has been applied to RC joints with different joint reinforcement arrangements with minor to severe damage brought about by cyclic loading for the purposes of this work. Aiming at quantitative concluding remarks about the effectiveness of the repair technique, data concerning response loads, loading stiffness and energy absorption values have been acquired and commented upon. Furthermore, comparisons of damage index values and values of equivalent viscous damping, as obtained during the test of the original specimens, with the corresponding ones observed in the loading of the repaired ones have also been evaluated and commented. Based on these comparisons, it is deduced that the technique under investigation can be considered to be a rather satisfactory repair technique for joints with minor to moderate damage taking into account the rapid, convenient and easy-to-apply character of its application.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.154-159
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• 1999

In this paper we present tile results of an experimental investigation on the physical and mechanical properties of carbon fiber grid, polymer mortar, and carbon fiber grid reinforced plain concrete flexural members. In order to repairing and reinforcing damaged and/or deteriorated existing concrete structural members, new materials have been developed and utilized in the construction industries. But the physical and mechanical behaviors of the material are not well understood. To use the material effectively various aspects of the material must be throughly investigated analytically as well as experimentally. In this investigation we found the physical and mechanical properties of carbon fiber grid and polymer mortar which are directly utilized in the repair and reinforcement design of damaged or deteriorated concrete structures. In addition, we also investigate the strengthening effect of carbon fiber grid on the plain concrete flexural test specimens. It was found that the material can be used to repair and strengthen the concrete structures effectively.

• Computers and Concrete
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• 제11권4호
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• pp.351-364
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• 2013

This paper presents results from an analytical investigation of the behavior of steel reinforced concrete circular column sections with additional Glass Fiber Reinforced Polymers (GFRP) bars. The primary application of this composite section is to relocate the plastic hinge region from the column-footing joint where repair is difficult and expensive. Mainly, the study focuses on the development of the full nominal moment-axial load (M-P) interaction diagrams for hybrid concrete sections, reinforced with steel bars as primary reinforcement, and GFRP as auxiliary control bars. A large parametric study of circular steel reinforced concrete members were undertaken using a purpose-built MATLAB(c) code. The parameters considered were amount, location, dimensions and mechanical properties of steel, GFRP and concrete. The results indicate that the plastic hinge was indeed shifted to a less critical and congested region, thus facilitating cost-effective repair. Moreover, the reinforced concrete steel-GFRP section exhibited high strength and good ductility.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.637-640
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• 2002

The deterioration of RC deck slabs has been a serious problem and high portion of budget has been a spent for repair and strengthening of deck slab. The concrete deck slabs are subject to direct application of vehicle loading and accumulation of fatigue damage. Besides, various environmental causes. In this paper, an probabilistic study is carried out to predict exact load effects and structural capacity of deck slab during its service life, and estimate an appropriate remaining life of deck slab. To achieve this purpose the live load model is developed using by influence line including deterioration of deck slab, and deterioration model of bridge deck slab is developed. In addition, the fatigue life of reinforced concrete deck slabs considering corrosion of reinforcement are estimated based on experimental formula. This study will help rational decisions for the management and repair of reinforced concrete deck slabs.

• Journal of Chest Surgery
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• 제27권10호
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• pp.888-892
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• 1994

Acquired, traumatic tracheoesophageal fistula [TEF] is rare and difficult problem to manage. This 55 years old man met with a roller accident of a tractor. During accident, he received a penetrating injury on the left upper sternal border. At local clinic, he received closed thoracotomy drainage [CTD]for relief of pneumothorax[left]. Three days after CTD, he complained abdominal pain and hematemesis. The endoscopy revealed large ulcer at the stomach, so he received subtotal gastrectomy. On 10th day post subtotal gastrectomy, he developed aspiration and coughing from a TEF. The esophagogram showed large TEF at the mid-trachea level. So he transfered to our hospital for operation. This patient was operated on for late TEF three weeks after injury. We have used absorble 4-0 Vicryl sutures to repair trachea. We repair all esophageal injuries with two layers of nonabsorbable silk suture. Where suture line on the esophagus, the strap muscle was interposed for reinforcement. And for feeding, the feeding jejunostomy was performed. Postoperatively the osteomyelitis of the manubrium site was developed, so on the 30th postoperative day, an ostectomy of manubrium, both clavicle and fight 1st, 2nd ribs, and the pectoralis major musculo-cutaneous flap coverage were performed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2473-2478
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• 2011

The asset management of railway facilities is a total framework for finally supporting a safe and comfortable train service, which includes functions of supporting evaluation of condition and performance of infrastructures, making the decision method of repair or rehabilitation of deteriorated facilities, and lengthening the life cycle of structure through the decision of adequate cost and time of repair or reinforcement. In the range of the asset management, organization, human, the target, and information & data of company are included. Therefore, in this paper, appling the method of asset management analysis to the railway structures, the process of the risk assesment using BRE(Business Risk Exposure) and the basis of consisting optimized renewal decision-making are expressed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.535-538
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• 2005

The problem of the crack which occures from the reinforced concrete structure. could be caused by the complexed factors. When the crack happen, it caused fatal blemish to manage and maintain the structure such as structural problem, licking, spalling, viewing Even though they study and work hard to solve this kind of problem in the world, there are no countermeasure for perfect prevention of crack. After the crack checked out, a method of repair-reinforcement has been sutdied and operated actively. In this experiment, studied durability of repair material. Experiment wave and durability of epoxy and urethane's were shown good result, and micro cement's durability displayed result that is not good. Result of a repeat tired experiment displayed result that micro cement is bad.

• Steel and Composite Structures
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• 제9권3호
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• pp.209-221
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• 2009

Heating correction, through heating and flattening a structure with a pressing machine, is the in-situ method used to repair buckled steel structures. The primary purpose of this investigation is to develop an FEM model which can predict the mechanical response of heat-corrected plates accurately. Our model clarifies several unsolved problems. In previous research, the location of the imperfection was limited to the center of the specimen although the mechanical behavior is strongly affected by the location of the imperfection. Our research clarifies the relationship between the location of the imperfection and the mechanical behavior. In addition, we propose further reinforcement methods and validate their effectiveness. Our research concludes that the strength of a buckled specimen can be recovered by heating correction and the use of an adequate stiffener.

• 한국재난정보학회 논문집
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• 제19권1호
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• pp.138-145
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• 2023

연구목적: 건축물의 노후화에 따른 보수, 보강 건축물의 증가에 따라 기 보강된 건축물에 화재가 발생시 화재 후 구조물에 미치는 영향성을 분석하여 보수, 보강대책의 기준을 마련하고자 한다. 연구방법: 콘크리트 배합설계에 의한 공시체를 제작하여 28일 양생 후 압축기를 통해 압축강도 측정 및 파괴를 유도후 에폭시로 보수, 보강하여 3일 양생 후 일부공시체를 재 압축강도시험을 실시하여 강도 복원 정도를 파악하고 보수, 보강한 나머지와 보수, 보강하지 않은 공시체를 실험용 전기로에 넣고 시간, 온도별로 가열한 후 압축강도를 실험하여 화재의 영향성을 추정함. 연구결과: 항복된 공시체를 에폭시로 보강한 후 실험용전기로에 넣어 가열을 시간별로 온도의 차이를 주어 실험한 결과 높은 온도에서 열 영향을 받는 시간이 길면 길수록 강도의 저하가 발생함을 알 수 있었고 보수, 보강되지 않은 공시체보다 더 강도 저하가 있음을 알 수 있었다. 결론: 이를 토대로 볼 때 에폭시 수지로 보수, 보강된 건축물이 화해를 입을 때는 일반 보수되지 않은 건축물보다 더 위험함을 알 수 있었으므로 화재에 대한 안정성을 고려하였을 때 보수보강 표면에 내화피복재 등을 도포하는 등 화재 취약에 대비하여야하겠다.

• 한국전통조경학회지
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• 제41권4호
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• pp.8-20
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• 2023

전통조경 시설물은 역사성과 진정성을 가진 기법에 따라 수리되어야 하지만 현행 문화재수리 표준시방서의 수리기준은 실무적 차원의 기본지침에 해당하며, 구체적인 사례를 통해 세부기법을 분석한 연구도 많지 않다. 본 연구는 조선시대 관영공간의 화계, 연못, 수로, 포장을 중심으로 역사적 사실에 근거한 수리기법을 시론하였다. 첫째, 화계는 석축 부재의 재료와 마감, 구조 강화와 뒤채움 재료, 상부 표토면 보호 조치를 분석하고, 기초보강용 석재와 교착용 미장재, 석재의 가공기법 등을 도출하였다. 특히 쇠시리와 모접기를 통한 세밀한 장대석 가공법, 기초보강용 엄석과 유회의 사용은 화계의 독특한 수리기법 중 하나로 확인되었다. 둘째, 연못의 경우 호안 석축의 재료와 구조, 기초부 보강과 누수 방지 기법을 살펴보면서 지정공사, 구부재 활용, 수질 관리 등에 관한 특징을 도출하였다. 고임쇠와 심석을 통한 내구성 강화, 기초부 강화를 위한 말뚝지정, 오물 유입 방지를 위한 사초 피복 등이 주목할 만한 수리기법으로 확인되었다. 셋째, 수로는 축조 재료, 기초부 강화와 누수 방지 조치, 수해 예방 조치를 중점적으로 파악하면서 덮개돌 마감 방식, 지정과 뒤채움 재료, 유속 저감 방법 등의 수리기법을 파악하였다. 수량에 따른 다양한 바닥 재료, 누수 방지를 위한 강회 마감 등이 주요 수리기법으로 주목되며, 날개벽과 낙차공 등은 수로 내부의 충파와 유속 관리를 위한 조치로 확인되었다. 넷째, 포장은 기초부 구성, 부속 재료와 도구, 사초 활용 등에 관한 실제 사례를 제시하였다. 사초 피복을 통한 박석 고정, 세승으로 불린 기준실 사용 등이 주요 수리기법 중 하나였으며, 특히 방전장으로 불린 방전 포설 전문장인의 존재가 새롭게 확인되었다. 본 연구가 전통조경 시설물의 수리기법 발굴을 위한 출발점이 되고, 향후 시방서 개정을 위한 기초자료로 활용되길 기대한다.