• Smart Structures and Systems
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• 제23권1호
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• pp.81-90
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• 2019

The shear behavior of soil-concrete interface is mainly affected by the surface roughness of the two contact surfaces. The present research emphasizes on investigating the effect of roughness of soil-concrete interface on the interface shear behavior in two-layered laboratory testing samples. In these specially prepared samples, clay silt layer with density of $2027kg/m^3$ was selected to be in contact a concrete layer for simplifying the laboratory testing. The particle size testing and direct shear tests are performed to determine the appropriate particles sizes and their shear strength properties such as cohesion and friction angle. Then, the surface undulations in form of teeth are provided on the surfaces of both concrete and soil layers in different testing carried out on these mixed specimens. The soil-concrete samples are prepared in form of cubes of 10*10*30 cm. in dimension. The undulations (inter-surface roughness) are provided in form of one tooth or two teeth having angles $15^{\circ}$ and $30^{\circ}$, respectively. Several direct shear tests were carried out under four different normal loads of 80, 150, 300 and 500 KPa with a constant displacement rate of 0.02 mm/min. These testing results show that the shear failure mechanism is affected by the tooth number, the roughness angle and the applied normal stress on the sample. The teeth are sheared from the base under low normal load while the oblique cracks may lead to a failure under a higher normal load. As the number of teeth increase the shear strength of the sample also increases. When the tooth roughness angle increases a wider portion of the tooth base will be failed which means the shear strength of the sample is increased.

• 콘크리트학회지
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• 제8권6호
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• pp.173-182
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• 1996

이 연구에서는 콘크리트 보의 전단거동에서 콘크리트 압축강도가 스터럽 유효성에 미치는 영향을 실험적으로 연구하였다. 이를 위하여 단며이 $300{\times}600mm$ 인 수직 스터럽이 배근되지 않은 콘크리트 보 4개와 수직 스터럽이 배근된 콘크리트 보 20개에 대하여 실험을 수행하였다. 주요 실험변수는 2종류(보통강도, 고강도)의 콘크리트 압축강도 수준과 6종류의 전단철근비이다. 실험에 앞서 주어진 단면과 가정된 재료 상수에 대하여 ACI Building Code를 사용하여 휨파괴가 유발되는 전단철근비( ${\rho}_vACI$)를 산정하였으며, 이 값을 기준으로 6종류의 전단철근비를 선택하였다. 실험결과, 스터럽이 배근되지 않은 콘크리트 보에 있어서 ACI 전단강도식의 안전율은 콘크리트의 압축강도가 증가함에 따라 감소하는 것으로 나타났다. 그러나 스터럽이 많이 배근된 고강도 콘크리트 보에서는 보통강도 콘크리트 보 이상의 안전율이 확보되는 것으로 나타나 스터럽 유효성은 고강도 콘크리트 보에서 더 큰 것으로 나타났다.

• 한국강구조학회 논문집
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• 제21권2호
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• pp.127-134
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• 2009

본 연구의 목적은 경량콘크리트에 매립된 쉬어 커넥터의 전단거동 특성을 파악하는데 있다. 본 연구는 기존 실험결과와 유한요소해석에 의한 해석결과를 비교분석하여 유한요소 해석의 타당성을 확인하고 경량콘크리트의 압축강도($f_{ck}$) 변화에 따른 쉬어 커넥터의 전단강도를 기존 설계식(AISC-LRFD 및 Eurocode 4)과 비교분석하였다. 유한요소해석 결과 경량콘크리트에 매립된 쉬어 커넥터의 전단강도는 Eurocode 4의 쉬어 커넥터의 전단강도와 거의 일치하는 것으로 나타났다.

• 대한토목학회논문집
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• 제13권1호
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• pp.75-87
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• 1993

본 논문은 강섬유보강콘크리트 deep beam의 전단특성을 규명하고 균열전단강도와 극한전단강도를 예측하기 위한 것으로 섬유로 보강된 16개의 보를 포함한 총 20개의 보를 4 series로 나누어 실험을 수행하였다. 실험의 변수는 콘크리트의 강도, 섬유혼입률, 전단지간 등이며, 실험 과정을 통해 파괴형상, 처짐, 변형률, 전단강도 등을 측정 하였다. 실험결과로 부터 섬유의 혼입량이 많아지고, 콘크리트의 강도가 커질 수록, 그리고 전단지간이 짧아질수록 섬유보강콘크리트 deep beam의 균열 및 극한전단강도가 증가됨을 밝혔다. 또한, 실험성과를 회귀분석하여 균열전단강도와 극한전단강도 추정식을 제안 하였다. 제안된 추정식에 의한 계산값과 실험성과를 비교 검토하여 그 상관성을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1124-1131
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• 2008

Thanks to a new in-situ seismic probe, using bender elements and penetration scheme, a simple linear relationship between undrained shear strength(Cu) and shear wave velocity(Vs) was obtained. This priceless relationship is worthy to be illuminated further in ideal laboratory environment. To avoid sampling disturbance effect, special consolidation cylinders were used to make normally consolidated specimens from kaolinite suspension. The undrained shear strengths of the specimens were measured using unconsolidated undrained triaxial compression tests. Also shear wave velocity measurements were performedprior to shearing the same specimens, using the bender elements installed in the base pedestal and the top cap of the triaxial compression cell. The Cu-Vs relationship is fairly linear and supports the linear trend of clayey silt obtained using field testing. Also the classic density-shear modulus relationship for soft clay proposed by Hardin and Black(1969) was once more verified hereby.

• Steel and Composite Structures
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• 제28권2호
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• pp.251-266
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• 2018

Compared to conventional flat web I-beams, the prediction of shear buckling stress of corrugated web steel beams (CWSBs) is not straightforward. But the CWSBs combined advantages of lightweight large spans with low-depth high load-bearing capacities justify dealing with such difficulties. This work investigates experimentally and analytically the shear strength of trapezoidal CWSBs. A set of large scale CWSBs are manufactured and tested to failure in shear. The results are compared with widely accepted CWSBs shear strength prediction models. Confirmed by the experimental results, the linear buckling analyses of trapezoidal corrugated webs demonstrated that the local shear buckling occurs only in the flat plane folds of the web, while the global shear buckling occurs over multiple folds of the web. New analytical prediction model accounting for the interaction between the local and global shear buckling of CWSBs is proposed. Experimental results from the current work and previous studies are compared with the proposed analytical prediction model. The predictions of the proposed model are significantly better than all other studied models. In light of the dispersion of test data, accuracy, consistency, and economical aspects of the prediction models, the authors recommend their proposed model for the design of CWSBs over the rest of the models.

• 대한치과기공학회지
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• 제35권1호
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• pp.43-48
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• 2013

Purpose: This study aimed to investigate the shear bond strength for non-precious alloy castings without beryllium, which has been used repeatedly for economical reason. Methods: The Schmitz-Schulmeyer test method was used to evaluate the shear bond strength between the non-beryllium Ni-Cr alloy Vera Bond 2V(AlbaDent, Inc. USA) and the Ceramco 3(Dentstply, York, PA, USA) porcelain powder. The maximum loading and shear bond strength were measured. The average shear strength(MPa) was analyzed with the one-way ANOVA and the Tukey's test( =.05). The fracture specimens were examined using Microscope to determine the failure pattern. Results: The mean shear bond strengths(SD) in MPa were group A(100% new metal) control 28.72(3.31); group B(50% new + 50% reused) 27.28(1.13); group C(all reused) 26.61(5.47). Microscope examination showed that group A and B specimens presented mixed failure, and group C specimens showed adhesive failure. Conclusion: In conclusion, forward this non-precious alloy dose not contain beryllium for how should use a more systematic study and for future advanced research is performed giving effect to be considered desirable.

• 대한치과기공학회지
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• 제35권1호
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• pp.19-27
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• 2013

Purpose: The aim of this research was to evaluate the shear bond strength of different zirconia veneering ceramics with and without liner glass materials to yttria partially-stabilized tetragonal zirconia polycrystalline(Y-TZP). Methods: Five co mmercial zirconia veneering ceramics were used in this study, E-Max(EM), Creation ZI(CR), Cercon ceram kiss(CE), Triceram(TR) and Zirkonzahn ICE(ZI). All samples were prepared according to manufacturer's instructions. Experimental industrially manufactured Y-TZP ceramic blocks(diameter: 2.7 mm; height: 13.5 mm) were used in this study. Shear bond strength between zirconia ceramic coping and zirconia veneering ceramics were evaluated by the push-shear bond test. The fracture load data were analyzed using ANOVA and Scheffe's test(${\alpha}$=0.05). The fractured surfaces of zirconia core ceraimc and zirconia veneering ceramics were observed using a scanning electron microscope(SEM). Results: The mean shear bond strengths ranged from 20 MPa ($20.12{\pm}6.34$ MPa) to 66.6 MPa ($66.62{\pm}10.01$ MPa). The Triceram(TRG) showed the highest value and Creation ZI(CR) showed the lowest value. In all groups, Zirconia liner and glass material groups was significantly higher shear bond strength than without liner(P<0.05), with the exception of Cercon ceram kiss(CE)groups. Conclusion: Zirconia bonding materials may have the advantage of improved bond strength between zirconia ceramic core and veneering ceramics.

• 한국지반공학회논문집
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• 제18권1호
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• pp.79-89
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• 2002

폐기물 매립지에는 차수 및 보호기능을 하는 다양한 토목섬유가 사용된다. 토목섬유 사이의 접촉(interface) 전단강도는 사면에 설치되는 차수 및 최종 덮개시설의 안전한 설계를 위해 곡 필요한 물성치로서, 본 연구에서는 대형 직접전단 시험기를 사용하여 지오멤브레인(GM)과 지오텍스타일(GT) 사이의 접촉 전단강도를 측정하였다. 본 논문에서는 Mohr-Coulomb 파괴 포락선을 이용하여 전단강도를 평가하였으며, 연직하중, 수팀상태, 지오멤브레인(GM)의 표면상태-texturing 유무 - 등이 전단강도에 미치는 영향을 알아보았다. 분석 결과 연직하중이나 수침상태가 전단강도에 미치는 영향은 각각 하중의 크기와 토목섬유의 종류에 따라 정도가 다르게 나타났다. 사면에 설치되는 토목섬유의 경우, 다양한 현장조건-상재하중, 수침상태, 사용되는 토목섬유의 종류을 고려한 시험 결과를 통해 얻은 물성치를 이용하여야 안전한 설계가 될 수 있을 것이다.

• 대한치과보철학회지
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• 제45권4호
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• pp.407-418
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• 2007

Purpose: The objective of this study was to evaluate the effects of hydrofluoric acid concentration & etching time on the shear bond strength between IPS Empress 2 ceramic and resin cement. Material and methods: Thirty three rectangular shape ceramic specimens($20{\times}12{\times}5mm$ size, IPS Empress 2 core materials) were used for this study. The ceramic specimens divided into ten experimental groups with three specimens in each group and were etched with hydrofluoric acid(4%, 9%) according to different etching times(30s, 60s, 90s, 120s, 180s). Etched surfaces of ceramic specimens were bonded with resin cement(Rely X Unicorn) using acrylic glass tube. All cemented specimens were tested under shear loading until fracture on universal testing machine at a crosshead speed of 0.5mm/min and the maximum load at fracture(kg) was recorded. Collected shear bond strength data were analyzed with one way ANOVA and Duncan tests. All etched ceramic surfaces were examined morphologically using SEM(scanning electron microscopy). Results: Shear bond strength of etching group$(35.89{\sim}68.01MPa)$ had four to seven times greater than no-etching group$(9.53{\pm}2.29MPa)$. The ceramic specimen etched with 4% hydrofluoric acid for 60s showed the maximum shear bond strength$(68.01{\pm}11.78MPa)$. Ceramic surface etched with 4% hydrofluoric acid for 60s showed most retentive surface texture. Conclusion: It is considered that 60s etching with 4% hydrofluoric acid is optimal etching methods for IPS Empress 2 ceramic bonding.