• 콘크리트학회지
• /
• 제6권3호
• /
• pp.215-220
• /
• 1994

장부철근 하부의 콘크리트 코어의 지압강도 및 지압강성에 대한 실험이 수행되었으며, 그 연구결과가 정리되었다. 콘크리트의 압축강도, 장부철근의 직경, 콘크리트내에 철근의 위치가 지압강도 및 지압강성에 미치는 영향들이 연구되었으며, 이 결과들을 토대로 콘크리트 코아를 지지하는 장부철근에 대한 콘크리트의 지압강성 및 지압강도를 예측할 수 있는 실험식이 제안되었고, 그 결과와 실험치를 비교하였다.

• 자원환경지질
• /
• 제50권6호
• /
• pp.435-443
• /
• 2017

하내광상은 경상계 하양층군의 진동층 퇴적암내의 열극을 충진하여 발달한 함 동 열수 석영 맥상광상이다. 초기 맥상 석영과 함께 자류철석-황철석의 산출로 시작된 금속 광화작용은 자류철석-황철석 $\rightarrow$ 황철석-황동석-섬아연석(${\pm}$함비스무스 텔루라이드) 광화작용 $\rightarrow$ 함 은(Ag) 텔루라이드 광화작용 $\rightarrow$ 2차 광물 광화작용의 공생관계를 보이며 진행되었다. 유체포유물 가열실험 결과 하내 함 동 열수광화작용은 약 $400^{\circ}C$ 내지 $200^{\circ}C$ 온도조건의 열수계에서 진행되었다. 맥상 광물의 생성조합과 공생관계 및 유체포유물 가열실험 결과를 이용한 열역학적 해석결과, 하내 함 동 열수광체의 주된 함 동 광물인 황동석 주 광화시기 초기의 온도인 $350^{\circ}C$의 경우 $10^{-9.2}bar$의 황 분압조건에서 광화작용이 시작되었으며, $10^{-8.7}bar$에 이르는 황 분압조건과 ${\approx}10^{-32.1}bar$에서 ${\approx}10^{-29.8}bar$에 이르는 산소 분압조건에서 진행되었다. 주 광화시기 후기의 온도조건인 $250^{\circ}C$의 경우 ${\approx}10^{-13.5}bar$에서 ${\approx}10^{-13.2}bar$에 이르는 황 분압조건과 ${\approx}10^{-38.4}bar$에서 ${\approx}10^{-37.6}bar$에 이르는 산소 분압조건에서 시작되어 ${\approx}10^{-11.7}bar$ 및 ${\approx}10^{-35.2}bar$에 이르는 황 분압 및 산소 분압 각각의 점증에 의하여 진행되었다. 하내 열수계 최후기(${\geq}200^{\circ}C$) 텔루라이드 광화작용과 관련된 Te의 최소 분압조건은 ${\approx}10^{-18}bar$이며, 황 분압 조건은 ${\approx}10^{-14.0}bar$ 에서 ${\approx}10^{-10.9}bar$이었다.

• 한국도로학회논문집
• /
• 제15권1호
• /
• pp.23-36
• /
• 2013

PURPOSES: The problem under this circumstance is that the erosion not only drops strength of the steel dowel bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem, alternative dowers bars are developed. METHODS: In this study, the bearing stresses between the FRP tube dowel bar and concrete slab are calculated and compared with its allowable bearing stress to check its structural stability in the concrete pavement. These comparisons are conducted with several cross-sections of FRP tube dowel bars. Comprehensive laboratory tests including the shear load-deflection test on a full-scale specimen and the full-scale accelerated joint concrete pavement test are conducted and the results were compared with those from the steel dowel bar. RESULTS: In all cross-sections of FRP tube dowel bars, computed bearing stresses between the FRP tube dowel bar and concrete slab are less than their allowable stress levels. The pultrusion FRP-tube dowel bar show better performance on direct shear tests on full-scale specimen and static compression tests at full-scale concrete pavement joints than prepreg and filament-winding FRP-tube dowel bar. CONCLUSIONS: The FRP tube dowel bars as alternative dowel bar are invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Also, the pultrusion FRP-tube dowel bar performed very well on the laboratory evaluation.

• 한국산업융합학회 논문집
• /
• 제25권3호
• /
• pp.357-363
• /
• 2022

In this study, in order to develop an non-slip metal grating, the stability of the grating according to the span of the grating and the gap and height of the bearing bar was evaluated. The optimal shape design of the grating was performed using the results of determining the stability of the grating. The purpose of this study is to determine the stability according to the spacing and height of the bearing bar by applying the design pressure at the design stage to develop the anti-skid grating, and to design the optimal shape for cost reduction. In the optimal design, the target variable was set as the mass, and the optimal design of the grating was performed based on about 20%. Regardless of the height of the bearing bar of the grating, the stress and deformation of the span and the grating showed a proportional tendency to each other, and it was found that the stress decreased as the height of the bearing bar increased. Based on the structural analysis results, an optimal design was performed using mass as the objective variable, and the existing 2mm thickness was changed to 1.6mm, reducing the mass by about 19%. The stress increased by about 4.4% compared to the maximum stress of the existing grating, but the minimum safety factor was 3.1, indicating that the optimally designed grating was stable.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2001년도 춘계학술대회 논문집
• /
• pp.419-425
• /
• 2001

The shear modulus of 3-bar lap rubber shear dynamic test specimen is investigated through incremented shear strain tests. The shear force-strain relation of rubber specimen is also calculated by ABAQUS using hyper-elastic material properties of high damping rubber. The analysis results are compatible with shear dynamic tests of 3-bar lap rubber specimen and 1/8 reduced-scale laminated rubber bearing

• 한국공간구조학회논문집
• /
• 제20권4호
• /
• pp.123-130
• /
• 2020

Generally the non-bearing walls in apartment buildings in Korea are not considered as a lateral force resisting members for the design consideration. This engineering practice caused large crack damages and brittle fractures of the non-bearing walls when subjected to Pohang earthquakes in 2017 since those have not been designed for seismic loading. In this study, finite element analysis was conducted for slot type non-bearing wall connection system to reduce damages and concentrate damages to the designated damping device through separation from the structural wall members. Steel plate and dowel bar systems designed for the dissipation of seismic energies were modeled and analyzed to investigate the damage reductions. Finally, the test result and the analysis result were compared and verified.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.454-457
• /
• 2006

This study presents a strut-and-tie model for the development of headed bars in an exterior beam-column joint with transverse reinforcements. The tensile force of a headed bar is considered to be developed by head bearing together with bond along a bonded length as a partial embedment length. The model requires construction of struts with biaxially compressed nodal zones for head bearing and fan-shaped stress fields against neighboring nodal zones for bond stresses along the bonded length. Due to the existence of transverse reinforcements, the fan-shaped stress fields are divided into direct and indirect fan-shaped stress fields. A required development length and head size of a headed bar can be optimally designed by adjusting a proportion between a bond contribution and bearing contribution.

• Architectural research
• /
• 제22권1호
• /
• pp.33-39
• /
• 2020

In this study, side-face blowout failure strength of high strength headed reinforcing bar, which is vertically anchoring between RC or SFRC members, is evaluated throughout pullout test. The major test parameters are content ratio of high strength steel fibers, strength of rebar, length of anchorage, presence of shear reinforcement, and the side concrete cover thickness planned to be 1.3 times of the rebar. In pullout test, tensile force was applied to the headed reinforcing bar with the hinged supports positioned 1.5 and 0.7 times the anchorage length on both sides of the headed reinforcing bar. As a result, the cone-shaped crack occurred where the headed reinforcing bar embedded and finally side-face blowout failure caused by bearing pressure of the headed reinforcing bar. The tensile strength of specimens increased by 13.0 ~26.2% with shear reinforcement. The pullout strength of the specimens increased by 3.6 ~15.4% according to steel fiber reinforcement. Increasing the anchoring length and shear reinforcement were evaluated to reduce the stress bearing ration of the total stress.

• Geomechanics and Engineering
• /
• 제5권5호
• /
• pp.447-462
• /
• 2013

An analysis model for predicting the tip bearing capacity of drilled shafts in cohesionless soils is improved in this study. The evaluation is based on large amounts of drilled shaft load test data. Assessment on the analysis model reveals a greater variation in two coefficients, namely, the overburden bearing capacity factor ($N_q$) and the bearing capacity modifier for soil rigidity (${\zeta}_{qr}$). These factors are modified from the back analysis of drilled shaft load test results. Different effective shaft depths and interpreted capacities at various loading stages (i.e., low, middle, and high) are adopted for the back calculation. Results show that the modified bearing capacity coefficients maintain their basic relationship with soil effective friction angle ($\bar{\phi}$), in which the $N_q$ increases and ${\zeta}_{qr}$ decreases as $\bar{\phi}$ increases. The suggested effective shaft depth is limited to 15B (B = shaft diameter) for the evaluation of effective overburden pressure. Specific design recommendations for the tip bearing capacity analysis of drilled shafts in cohesionless soils are given for engineering practice.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
• /
• pp.239-243
• /
• 2003

A reducing bearing angle theory for bond of ribbed reinforcing bars to concrete is proposed to simulate experimental observation. Analytical expressions to determine bond strength for splitting and pullout failure are derived, where the bearing angle is a key variable. As bearing angle is reduced, splitting strength decreases and shearing strength increases. The proposed reducing bearing angle theory is effective to simulate damage of the deformed bar-concrete interface and understand bond mechanism of ribbed reinforcing steel in concrete structures.