• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
• /
• pp.769-774
• /
• 2000

The purpose of this study was to investigate the structural performance of reinforcement corrosion reinforced concrete beams strengthened with epoxy mortar system. Main test parameters are existence and the magnitude of the reinforcement corrosion and the reinforcing bar and the tensile reinforcement ratio of the specimens. eight beam specimens were tested to investigate the effectiveness of each test variables on maximum load capacity and failure mode. Test results showed that the ultimate moment of th specimens were higher tan the nominal moment and the flexural stiffness was increased about 2.5 times and the cracking moments occurred over 60% of the failure moment in comparison with same sized control beam. However, note that epoxy mortar may conduct member into brittle failure mode.

• Computational Structural Engineering : An International Journal
• /
• 제1권2호
• /
• pp.117-130
• /
• 2001

Investigations of low-rice unbounded reinforced concrete shear walls with or without openings are performed with comparison of analytical and experimental results. Theoretical analysis is based on nonlinear finite element algorithm, which incorporates concrete failure criterion and nonlinear constitutive relationships. Studios focus on the effects of height-to-length ratio of shear walls, opening ratio, horizontal and vertical reinforcement radios, and diagonal reinforcement. Analytical solutions conform well with experimental results. Equations for cracking, yielding and ultimate loads with corresponding lateral displacements are derived by regression using analytical results and experimental data. Also, failure modes of low-rise unbounded shear walls are theoretically investigated. An explanation of change in failure mode is ascertained by comparing analytical results and ACI code equations. Shear-flexural failure can be obtained with additional flexural reinforcement to increase a wall's capacity. This concept leads to a design method of reducing flexural reinforcement in low-rise bounded solid shear wall's. Avoidance of shear failure as well as less reinforcement congestion leer these walls is expected.

• Computers and Concrete
• /
• 제27권4호
• /
• pp.385-393
• /
• 2021

Reinforcement corrosion is the main cause of the durability failure of reinforced concrete (RC) structure. In this paper, a three-dimensional (3D) numerical model of macro-cell corrosion is established to reveal the corrosion mechanisms of steel reinforcement in RC structure. Modified Direct Iteration Method (MDIM) is employed to solve the system of partial differential equations for reinforcement corrosion. Through the sensitivity analysis of electrochemical parameters, it is found that the average corrosion current density is more sensitive to the change of cathodic Tafel slope and anodic equilibrium potential, compared with the other electrochemical parameters. Furthermore, both the anode-to-cathode (A/C) ratio and the anodic length have significant influences on the average corrosion current density, especially when A/C ratio is less than 0.5 and anodic length is less than 35 mm. More importantly, it is demonstrated that the corrosion rate of semi-circumferential corrosion is much larger than that of circumferential corrosion for the same A/C ratio value. The simulation results can give a unique insight into understanding the detailed electrochemical corrosion processes of steel reinforcement in RC structure for application in service life prediction of RC structures in actual civil engineer.

• 한국지진공학회논문집
• /
• 제17권6호
• /
• pp.271-278
• /
• 2013

The hysteretic behavior of diagonal reinforced coupling beams is excellent during earthquakes. However, construction of the diagonal reinforced coupling beams is difficult due to complex reinforcement details required by current code procedures (ACI 318-11). Due to the detail requirement, reinforcement congestion and interference among transverse reinforcement always occur during construction field. When the aspect ratio of the beam is large, the interference of reinforcement becomes more serious. The objective of this paper is to simplify the reinforcement details of slender coupling beams by reducing transverse reinforcement around the beam perimeter. For this purpose, high- performance fiber reinforced cementitious composites are used for making coupling beams. Experiments were conducted using three specimens having aspect ratio 3.5. Test results showed that HPFRCC coupling beams with half the transverse reinforcement required by ACI 318-11 provided identical seismic capacities to the corresponding coupling beams having requirement satisfying the requirement specified in ACI 318-11.

• 한국구조물진단유지관리공학회 논문집
• /
• 제26권5호
• /
• pp.86-94
• /
• 2022

전 세계적으로 철근의 부식으로 인해 발생하는 철근 콘크리트 구조물의 성능 저하를 해결하기 위하여, FRP를 철근으로 대체하는 것은 상당한 주목을 받고 있으며, FRP 물성을 향상시켜 구조물의 사용 수명을 연장하기 위한 기술 개발이 진행되어 왔다. 이에 따라, 고강도 및 고강성을 갖는 국산형 CFRP rod와 CFRP grid의 개발 및 제조 기술이 필요하며, 이를 적용한 구조 부재의 거동을 평가한 연구가 수행되어야 한다. 본 연구에서는 국내 시범 생산 CFRP rod를 보강근으로 사용한 보 부재의 휨 전단 거동을 보강비와 전단 경간비에 따라 검토하였다. 그 결과, 일정 범위를 벗어난 보강비를 사용할 경우, CFRP rod에 의한 성능 개선 효과가 상쇄되거나 효과가 크지 않는 것으로 나타났다. 한편, CFRP rod를 사용한 보 부재의 경우, 국내 구조 설계 기준에 근거하여 전단 철근을 배치하더라도 전단 파괴 가능성이 발생하였다. 그러므로 CFRP rod를 사용한 보 부재의 경우, 보강비 제한과 전단파괴를 방지하기 위한 검토가 필요한 것으로 판단된다. 또한, CFRP rod를 사용한 보 부재의 연성은 변형 에너지 평가방법에 따라 결정되므로, 보 부재의 구조 거동을 반영한 변형 에너지 평가법을 적용하여 연성을 평가해야 한다.

• Structural Engineering and Mechanics
• /
• 제74권6호
• /
• pp.757-769
• /
• 2020

Granite is commonly used in the construction of the ancient stone pagodas of Korea. The material has excellent weathering resistance and durability, as well as high compressive strength. Most of the stone-made state-designated architectural heritage of Korea is made of granite. Therefore, the understanding of the structural feasibility of stone-made architectural heritage is crucial. Even though, until now, experimental studies for the reinforced stone have been rarely performed. This study intends to suggest a new methodology for the reinforcement of granite using a threaded titanium bar. Through the experimental study, the flexural behavior of the reinforced granite depending on the reinforcement ratio is investigated. Based on the test results, a moment-displacement relationship for the design of reinforced granite is suggested.

• Structural Engineering and Mechanics
• /
• 제67권1호
• /
• pp.93-104
• /
• 2018

The seismic behavior of reinforced concrete (RC) short columns with limited transverse reinforcement is investigated in this paper through an experimental program. The experimental program consists of four small-scale RC columns with an aspect ratio of 1.7, which are tested to the axial failure stage. The cracking patterns, hysteretic responses, strains in reinforcing bars, displacement decomposition and cumulative energy dissipation of the tested specimens are reported in detail in the paper. The effects of column axial load are investigated to determine how this variable might influence the performance of the short columns with limited transverse reinforcement. Brittle shear failure was observed in all tested specimens. Beneficial and detrimental effects on the shear strength and drift ratio at axial failure of the test specimens due to the column axial load are found in the experimental program, respectively.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
• /
• pp.37-40
• /
• 2004

An experimental study was conducted to investigate the stress-strain behavior of confined concrete columns according to transverse reinforcement volumetric ratio. Uniaxial loading tests of eleven column specimens$(250\times100\times500mm)$ with rectangular section were conducted to study effect of confinement. The main variables in this test are transverse reinforcement volumetric ratio and cross tie arrangement. the results indicate that the strength and the ductility of confined concrete columns are subjected to transverse reinforcement volumetric ration and cross tie arrangement.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.177-180
• /
• 2006

Experimental study has been performed in order to evaluate the effects of steel reinforcement ratio on the flexural behavior of RC beams strengthened with CFRP sheets. The steel reinforcement ratio of $0.78%({\rho}_s/{\rho}_b=24%)$ is selected to have balance failure when control RC beams were strengthened with 1 ply CFRP sheet. Total 6 half-scale specimens were manufactured including each unstrengthened specimens, which have 3 different reinforcement ratios. The specimens strengthened with CFRP sheet consist of under- or over-reinforced beams for the balanced failure condition. Moreover, the behavior of un strengthened or strengthened beams were compared to evaluate flexural performance. The results of this study show that the over-reinforced specimens were failed by concrete crushing prior to CFRP sheet failure by debonding or rupture. On the contrary, the under-reinforced specimen were failed by rupture of CFRP sheet.

• Journal of Construction Engineering and Project Management
• /
• 제7권4호
• /
• pp.13-19
• /
• 2017

This study is based on the use and performance of bamboo reinforcements in construction of low-cost structures. This study investigated the physical and mechanical properties of bamboo reinforcements. Bamboo reinforced concrete beam specimens were tested with different reinforcement ratios and observed the load capacity, deflection and failure patterns. It was observed that, flexural strength of bamboo reinforced column is sufficient higher than plain cement concrete and comparable to steel reinforced concrete beams. Bamboo reinforced concrete columns with different reinforcement ratio also tested and observed the ultimate compressive strength and failure pattern. It found, all columns failed in a similar pattern due to crushing of concrete. According to cost analysis, bamboo reinforced beams and columns with moderate reinforcement ratio showed the best strength-cost ratio among plain cement concrete and steel reinforced concrete.