• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.881-891
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• 2008

The purpose of the present study is to investigate the influence of seasonal temperature variation on the thermal stresses in roller compacted concrete dam(RCD) structures. Using the finite element code, DIANA performs 2-D transient temperature and resultant stress analysis for RCD. Time variability of the mesh geometry is considered in order to simulate successive phases of the structure's construction. The main analysis variables are construction sequence, concrete temperature and ambient temperature. The results show principal tensile stress of hot-weathering concrete is higher than that of cold-weathering concrete. In some case the index of thermal cracking excesses 1.0, RCD also needs thermal management on placing temperature according to weather condition.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.125-133
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• 2014

In this study, experimental research was carried out to investigate the seismic and structural performance of precast concrete exterior beam-column joints using bolt type connection and prestressing method. A total of five full-scale exterior beam-column joints were constructed and tested under reversed cyclic loading, controlled by displacement. Results of the test are as follows: Energy dissipation capacity and pinching phenomenon of PC beam-column joints showed disadvantageous behavior compared to RC beam-column joints. However, drift capacity of the PC joint was excellent. Also, yield mechanism concentrated on embedded nuts was suitable as an exterior beam-column joint of lateral load resistance frame. Additional application of prestressing method was also very effective to control excessive pinching and cracking in the joint region, and thus improved an overall seismic performance of the PC joint.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.12-13
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• 2020

Construction projects and buildings are becoming taller and larger, and the size of water tanks of production facilities and high-rise buildings is also gradually increasing. Most large water tanks apply a waterproofing layer to the water tank type concrete structure. The application of polyurea coating materials, which are excellent in water resistance, chemical resistance, physical performance, rapid hardening, and workability is gradually increasing as waterproofing and anticorrosion layer for water tank. As a result, defects such as water leakage and damage to the waterproofing layer are continuously occurring, causing production disruption, setback to users. Therefore, it is required to review suitability through performance verification of the waterproofing and anticorrosion system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.809-817
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• 2008

Recently, the external prestressing method is being much frequently used in strengthening reinforced concrete structures because of it's excellent load resistance and serviceability increases comparing to other strengthening methods. However, it is true that the research on fatigue performance of concrete structures strengthened by the external prestressing using FRP tendons is rare. Therefore, the purpose of this study is to evaluate the safety and feasibility of the external prestressing method by analyzing the characteristics of the reinforced concrete beam strengthening using FRP tendons under repeated loads. Test variables adopted in this experimental study are the types of external prestressing material (steel or FRP tendon) and the repeated load ranges. The repeated load range have the minimum 50% of yield load of reinforced concrete beam and the maximum 70-85%. The test beams are loaded by 4 point loadings with 3 Hz sine wave. From this experimental study, it is confirmed that the reinforced concrete beams strengthened using FRP tendons have sufficient safety against fatigue, especially in FRP tendon itself, tendon at deviators and tendon at anchorages.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.165-174
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• 2010

This study was conducted to evaluate the feasibility of expedite repairing of concrete pavements using precast concrete pavement method and to investigate the effectiveness of slab connection methods. In the demonstration construction, four slabs of jointed concrete pavements were replaced with the precast slabs. First, precast concrete slabs were designed and fabricated, then existing slabs were cut and removed, and finally precast slabs were installed. The slabs were leveled and pockets, holes, and space between the slab bottom and the underlying layer were grouted. From the demonstration construction, details about the design and construction of the precast pavements for repairing of pavements were evaluated. In addition, the slab connection methods such as pocket and hole connection methods were applied in the construction and the slab curling behaviors at the joints that include those connection methods were compared. The results showed that both slab connection methods were applicable, and the hole connection method was superior.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.527-534
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• 2006

This paper outlines a new strengthening technique for concrete beams using externally unbended high-strength bars. The advantages of proposed method lie in speed and simplicity of construction compared to the alternative strengthening method. Externally unbended reinforcement retains many of the advantages over external unbended prestressed tendons. It eliminates time consuming stressing operations. Clearance requirements around anchorages are reduced as access is not required for prestressing jacks. Test results of eight specimens on reinforced concrete beams using different reinforcement materials such as carbon fiber sheet, steel plate and high-tension bar are reported. The beam strengthened by carbon fiber sheet showed a brittle failure mode due to the separation of fiber. As a result of draped profile of external bar, the maximum strength of the beam were increased by up to 212 percent and the deflections were reduced by up to 65 percent. Test results show that the beams reinforced with high-tension bar are superior to reference specimens, especially for the strength and deformation capacity.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.360-363
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• 2009

토목구조물의 설계 패러다임이 2차원에서 3차원으로 전환될 때 효율성과 재활용성의 관건이 되는 기술적 제약사항이 호환성이다. 대부분의 캐드 엔진이 형상모델 수준에서 호환성 혹은 연계성을 지원하고 있지만 3차원 정보모델에서 요구하는 정보모델의 호환성은 지원하고 있지 않은 실정이다. 이 논문에서는 콘크리트 박스 교량에 대해서 3차원 교량 정보 모델을 구성하고 건설 프로세서에서 이를 활용할 수 있는 방안을 시범적으로 적용한 사례를 정리하였다. 적용 대상 구조물은 FSM 공법으로 시공되는 경간 40미터의 콘크리트 박스거더 교량이다. 견적, 시공시뮬레이션, 해석 등의 프로세서의 요구사항을 반영한 분류체계에 따라 형상모델의 체계를 정의하고 각각의 형상모델 단위에 정보를 부여하는 방식을 사용하였다. 개별 프로세서를 위한 솔류션에서 이러한 형상과 정보가 연계된 내용을 받아들이거나 캐드 엔진에서 필요한 형태로 내보내는 방식을 모두 시도하였다. 3차원 형상 모델과 시간이 부여된 4D 시뮬레이션을 활용하여 공사 스케쥴에 따라 모델 레이어 분류 작업으로 공사 진행 단계가 가상으로 보여진다. 시범 적용을 통해서 가상건설 시스템의 구성하는 개별 솔류션 혹은 정보체계에 대한 문제점과 개선사항을 도출하였다.

• 한국도로학회지:도로
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• v.10 no.2
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• pp.58-67
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• 2008

교통량이 많은 도심지내 장대 지하차도 건설은 교통정체 해소에 기여를 하지만 초기 공사비가 많이 소요되는 단점이 있다. 또한, 화재등 유고시 이용자의 안전을 최우선으로 고려되어야 한다. 즉, 장대 지하차도 건설에 있어서 경제성과 안전성이 함께 만족할 수 있는 건설 방안이 필요하다. 세종지하차도는 이러한 문제점을 극복하고자 다음과 같이 지하차도의 환기방식 및 단면, 포장형식, 사고 예방 및 발생시를 대비한 종합방재시스템을 구축하였다. $\cdot$환기방식은 종류식 환기방식의 경제성과 횡류식 환기방식의 제연성능을 겸비할 수 있는 조합형 환기방식과 Duct Arch 단면을 적용하여 공사비 절감 및 운영시 유지관리비를 획기적으로 절감하였다. $\cdot$지하차도 포장형식은 화재시 내화성이 우수하며 유독가스 발생이 없는 HPC(고성능 콘크리트 포장) 포장을 적용하여 이용자의 안전을 최우선으로 고려하였고 일반 아스팔트 포장 및 배수성 아스팔트 포장에 비해 우수한 성능과 공용수명을 가진 공법을 적용함으로서 유지보수비용의 절감을 가능하게 하였다. 또한, 콘크리트포장의 단점인 소음발생을 최소화하기 위해 타이닝과 그루빙을 적용하였다. $\cdot$지하차도내 화재 등 유고시 신속한 대피가 가능하도록 피난 연락문 간격을 167m 간격으로 설치하고 비상탈출계단 6개소를 확보하였다. 또한 노약자 및 환자의 지하차도 외부로 대피를 돕기 위해 비상엘리베이터 3개소를 설치하는 등 사고발생 시 종합적으로 대처할 수 있는 시스템을 마련하여 적용하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.72-80
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• 2018

In this research, we tried to investigate the influence of concrete on cracks after applying to the actual construction site using the TPS construction method which can be easily charged by the mechanical injection method. To summarize the results, the following It is as follows. First, in the case of ultrasonic velocity, it can be seen that the ultrasonic wave passes rapidly at an average of about 36 mm / sec as compared with the syringe method when using the TPS method, and in the case of the injection depth, the syringe method In the case of TPS construction method, it showed an excellent tendency that 100% of the water retentive material was charged with all the formulations under a strong injection pressure. In the case of compressive strength, it was shown that the average was increased by 16.8% at the time of using the TPS construction method, and it was found to be structurally superior. Taken together, it is possible to confirm the behavior of the crack repairing agent by improving the quality by improving the strength and confirming the window installation by filling the injection material into the closed space at the crack site when using the TPS method compared with the syringe method. In addition, it is expected that construction time will be improved by shortening the construction period of about 5 days for the TPS construction method construction section 532 m, and usability will be expanded by the crack repair method of concrete structure.

• Journal of the Korea Institute of Building Construction
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• v.14 no.6
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• pp.571-581
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• 2014

In the present study, hollow precast concrete wall (PC Double Wall) for staircase construction was developed. Comparing the conventional walls, the PC Double Wall can be reduced the lift weight using hollow core and improves the integrity between the PC members. The cross-section and re-bar details of the PC Double Wall were developed considering precast concrete manufacturing, constructability, and the structural safety. Particularly, a form system was developed to manufacture thin and hollow core PC wall efficiently. A mock-up test for a staircase using the PC Double wall was performed to verify the constructability and integrity of the PC walls. The test result verified that joint deformation and cracking did not occur as showing good constructability.