• Title, Summary, Keyword: compressive strain

Search Result 1,015, Processing Time 0.036 seconds

A study on the unconfined compressive strength(UCS) of fiber-reinforced soil (섬유보강 혼합토의 일축압축강도 특성에 관한 연구)

  • 장병욱;김강석;박영곤
    • Proceedings of the Korean Society of Agricultural Engineers Conference
    • /
    • /
    • pp.461-466
    • /
    • 1998
  • The purpose of this study was to evaluate the properties of unconfined compressive strength(UCS) of dry soil which was reinforced with short polypropylene fiber(SPPF). And the results were summarized as follows: 1. As water content was increased, unconfined compressive strength and strain of dry soil with no fiber added were decreased 2. As mixing ratio of fiber was increased, unconfined compressive strength and strain at failure of dry soil reinforced with SPPF were increased. 3. When mixing ratio was larger than 0.5%, unconfined compressive strength was gradually increased. 4. The longer fiber was, the larger post peak strength was obtained and the larger strain was reached.

  • PDF

Effect of Strain Rate and Material Hardness on Residual Stress in Multiple Impact Shot Peening (다중충돌 쇼트피닝에서 변형률 속도와 소재 경도가 잔류응력에 미치는 영향에 관한 연구)

  • Kim, Tae-Woo;Yang, Zhao-Rui;Na, Doo-Hyun;Lee, Young-Seog
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.35 no.11
    • /
    • pp.1369-1375
    • /
    • 2011
  • Shot ball impacts to materials cause residual compressive stress on their surfaces. Improving the fatigue strength of a material that has this residual compress stress is the purpose of the shot peening process. A numerical study was performed to evaluate the effect of the strain rate sensitivity and hardness of the shot ball on the residual compressive stress. We calculated the residual compressive stress due to multiple impact shot peening using ABAQUS 6.9-1. AISI 4340 steel was the material used in this study. We compared the effects of high strain rate sensitivities and low strain rate sensitivities and found that when the material's sensitivity to the strain rate increased, the residual compressive stress decreased. In addition, the residual compressive stress of low-hardness material is higher than that of high-hardness material.

Effect of Bending Test Procedure on the Degradation Behavior of Critical Current in ReBCO Coated Conductor Tapes

  • Shin, H.S.;Dedicatoria, M.J.;Lee, N.J.;Oh, S.S.
    • Progress in Superconductivity and Cryogenics
    • /
    • v.11 no.4
    • /
    • pp.12-15
    • /
    • 2009
  • The $I_c$ degradation behavior of critical current in differently processed YBCO and SmBCO CC tapes with IBAD template has been investigated. It has been known that the residual strain in the CC tape will influence the shape of the $I_c$-strain window; $I_c$ may show a peak value if there exist a residual strain induced in the tape during manufacturing. The difference of residual strain may be resulted from the adopted different deposition techniques. In this study, bending test of CC tapes has been done using the Goldacker bending test rig which can produce both compressive and tensile bending strain continuously or alternately to the sample. For SmBCO CC tapes, in continuous compressive bending test, $I_c$ showed a minimal increase and did not degrade up to the largest strain that can be applied using the bending rig equivalent to 1.15% based on the sample thickness. However, in the case of alternate application of compressive and tensile bending strain, $I_c$ showed a larger degradation and a lower reversible limit when compared with the case of continuous application of the bending strain. When $I_c$ started to degrade significantly at the tension side, the reversibility ended, also at the compression side which is resulted from the permanent deformation like delamination or cracks that was induced due to tensile bending strain.

Dynamic Strength Variation of Glass Epoxy Composites with respect to Strain Rates (변형률 속도에 따른 유리섬유 에폭시 복합재료의 동적 강도 변화)

  • 임태성;이대길
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • /
    • pp.83-88
    • /
    • 2001
  • In this study, the tensile and compressive tests of glass fiber epoxy composites were performed to measure the strength variation with respect to strain rates of 1-200 $\textrm{sec}^{-1}$. In addition, tensile and compressive tests of 50-200 $\textrm{sec}^{-1}$ strain rates were conducted at a low temperature ($-60^{\circ}C$) to investigate the effects of temperature on the strength variation. From the test results, it was found that the tensile and compressive strengths increased about 100% and 70%, respectively, at the strain rates of 10-100 $\textrm{sec}^{-1}$ compared to the quasi-static strengths while the strengths were little affected by the environmental temperature variation.

  • PDF

Ductility Capacity of Slender-Wind R/C Walls (긴 세장한 R/C 벽체의 연성능력)

  • 홍성걸
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • /
    • pp.202-212
    • /
    • 2000
  • This study investigates the ductility capacity of slender-wide reinforced concrete walls under predominant flexural moment loading. The experimental work for this study aims to provide design guidelines for bar detailing in critical regions under compressive stress in particular in case of slender-wide RC walls. According to the experimental observation the Bernoulli hypothesis of linear strain distribution is no longer valid and the ultimate compressive strain of concrete is significantly reduced, It is postulated that the nonlinear strain distribution causes the concentrated compressive stressed region and hence the premature crushing failure at the toe of walls. The reduced ultimate strain and nonlinear strain distribution need transverse reinforcement for confinement and more realistic models for the strength and displacement estimation of slender-wide RC wall.

  • PDF

Stress-strain relationships for steel fiber reinforced self-compacting concrete

  • Aslani, Farhad;Natoori, Mehrnaz
    • Structural Engineering and Mechanics
    • /
    • v.46 no.2
    • /
    • pp.295-322
    • /
    • 2013
  • Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, toughness, energy absorption capacity and fracture toughness. Modification in the mix design of SCC may have a significant influence on the SFRSCC mechanical properties. Therefore, it is vital to investigate whether all of the assumed hypotheses for steel fiber reinforced concrete (SFRC) are also valid for SFRSCC structures. Although available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates material's mechanical properties. The present study includes: a) evaluation and comparison of the current analytical models used for estimating the mechanical properties of SFRSCC and SFRC, b) proposing new relationships for SFRSCC mixtures mechanical properties. The investigated mechanical properties are based on the available experimental results and include: compressive strength, modulus of elasticity, strain at peak compressive strength, tensile strength, and compressive and tensile stress-strain curves.

Stress and Strain for Perated Tensile Specimen -Experiemental Measurements and FEA Simulations

  • Um, Gi-Jeung;Kim, Hyoung-Jin
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
    • /
    • /
    • pp.489-494
    • /
    • 2006
  • The strain distribution in the vicinity of a hole in a tensile strip was measured using an image correlation method. The objective of this study is to evaluate the capability of predicting the strain component response using a constitutive model that was developed for use with paper materials. The need for a special constitutive model for paper derives from the characteristics of pronounced anisotropy and the fact that the material behaves differently under compressive loading than it does under tensile loading. The results of the simulation showed that predictions of strain distribution around the hole were in agreement with the experimental result trends, however, the agreement deteriorated as the edge of the hole was reached. It was observed that there is extensive inelastic strain that takes place around the hole prior to failure of the tensile strip. The simulation results showed that any difference between tensile and compressive behavior that may exist for paper material does not have any significant effect for the problem of this study because the level of compressive stress is quite low in comparison with compressive failure values.

  • PDF

Stress-strain behavior and toughness of high-performance steel fiber reinforced concrete in compression

  • Ramadoss, P.;Nagamani, K.
    • Computers and Concrete
    • /
    • v.11 no.2
    • /
    • pp.149-167
    • /
    • 2013
  • The complete stress-strain behavior of steel fiber reinforced concrete in compression is needed for the analysis and design of structures. An experimental investigation was carried out to generate the complete stress-strain curve of high-performance steel fiber reinforced concrete (HPSFRC) with a strength range of 52-80 MPa. The variation in concrete strength was achieved by varying the water-to-cementitious materials ratio of 0.40-0.25 and steel fiber content (Vf = 0.5, 1.0 and 1.5% with l/d = 80 and 55) in terms of fiber reinforcing parameter, at 10% silica fume replacement. The effects of these parameters on the shape of stress-strain curves are presented. Based on the test data, a simple model is proposed to generate the complete stress-strain relationship for HPSFRC. The proposed model has been found to give good correlation with the stress-strain curves generated experimentally. Inclusion of fibers into HPC improved the ductility considerably. Equations to quantify the effect of fibers on compressive strength, strain at peak stress and toughness of concrete in terms of fiber reinforcing index are also proposed, which predicted the test data quite accurately. Compressive strength prediction model was validated with the strength data of earlier researchers with an absolute variation of 2.1%.

Evaluation for Applications of Displacement Criterion by the Critical Strain of Uniaxial Compression in Rock Mass Tunnel (일축압축 한계변형률에 의한 암반터널 변위기준 적용성 평가)

  • Kim, Young-Su;Kim, Dae-Man
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.29 no.6C
    • /
    • pp.321-329
    • /
    • 2009
  • Laboratory compressive test was conducted on 6 different types of rock in order to investigate the characteristic of critical strain under uniaxial and triaxial stress condition. The results of uniaxial compressive test mostly ranged within 1~100MPa, the critical strain was also located between 0.1~1.0%. Therefore the results distributed within the upper and lower boundary proposed by Sakurai (1982). And the failure/critical strain ratio (${\varepsilon}_f/{\varepsilon}_0$) showed between 1.0~1.8 value depending on the uniaxial compressive strength. The results of critical strain by triaxial compressive test showed below 0.8% value for all test, the M value calculated from uniaxial and triaxial compressive test results ranged 1.0~8.0 for most of rock specimens. It is concluded that failure strain (${\varepsilon}_{f3}$) of rock mass, which is in triaxial stress condition is larger than the results of uniaxial stress condition (${\varepsilon}_{f1}$) by 1.0~8.0 times and value showed 1.0~1.8 larger value than critical strain (${\varepsilon}_{01}$). Therefore it is a conservative way for rock tunnel to use critical strain (${\varepsilon}_{01}$) calculated from a uniaxial compressive strength on tunnel displacement monitoring.

  • PDF

Earthquake-Resistance of Slender Shear Wall with No Boundary Confinement (단부 횡보강이 없는 세장한 전단벽의 내진성능)

  • 박홍근;강수민;조봉호;홍성걸
    • Journal of the Korea Concrete Institute
    • /
    • v.12 no.5
    • /
    • pp.47-57
    • /
    • 2000
  • Experimental and numerical studies were done to investigate seismic performance of slender shear walls with no boundary confinement that are principal structural members of high0rise bearing wall buildings. 1/3 scale specimens that model the plastic region of long slender shear walls subjected to combined axial load and bending moment were tested to investigate strength, ductility, capacity of energy dissipation, and strain distribution, The experimental results show that the slender shear walls fail due to early crushing in the compressive boundary, and then have very low ductility. The measured maximum compressive strain is 0.0021, much less than 0.004 being commonly used for estimation of ductility. This result indicates that the maximum compressive strain is not a fixed value but is affected by moment gradient along the shear wall height and distance from the neutral axis to the extreme compressive fiber.