• Journal of the Korea institute for structural maintenance and inspection
• /
• v.2 no.4
• /
• pp.201-208
• /
• 1998

To observe the confinement effects of Carbon Fiber Sheet(CFS) on the high-strength R/C short columns, Fifteen specimens with CFS were manufactured and tested under uni-axial compressive load. Major variables of this study are amount, spacing, type of CFS and amount of transverse steel. Increasing the amount of transverse steel and CFS, compressive strength and axial rigidity is improved. R/C columns with transverse steel and CFS exhibited less axial stress than columns with only CFS. From the test results, it is shown that the area confined with transverse steel and CFS is considerably important to evaluate axial stress of R/C short columns.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.135-140
• /
• 1999

The size effect of axial compressive strength of concrete in notched specimens was experimentally investigated. Based on the concept of the fracture mechanics and size effect law, theoretical studies for axial compressive failure of concrete were reviewed, and two failure modes of concrete specimen under compression were discussed. In this study, experiment of axial compressive failure, which is one of the two failure modes, was carried out by using double cantilever fracture specimens. By varying the slenderness of cantilevers and the eccentricity of applied loads with respect to the axis of each cantilever, the size effect of axial compressive strength of concrete was investigated, and predicted by Bazant's size effect law. The test results show that size effect appears conspicuously for all series of specimens. For the eccentricity of loads, the influence of tensile and compressive stress at the notch tip are significant and so that the size effect is varied. In other words, if the influence of tensile stress at the notch tip grows up, the size effect of concrete increases. And the fact that the fracture process zone must be sufficiently secured for more accurate experiment was affirmed.

• 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%.

• Journal of the Korean Ceramic Society
• /
• v.51 no.5
• /
• pp.487-491
• /
• 2014

In this study, we measured the thermally and chemically induced residual stresses on glaze using the photoelastic method. Porcelain with thermally induced residual stress showed compressive stress of 49 MPa for thermal expansion mismatch and a locally fluctuated stress field over the glaze layer due to compensation of compressive stresses around pores. In the case of chemically strengthened porcelain, the compressive stress on the glaze was 151 MPa which was around 3 times higher than the stress on thermally strengthened glaze. The trend of fracture strength of thermally and chemically strengthened porcelains was coincident with that of the residual stress of porcelains.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.19 no.3
• /
• pp.139-151
• /
• 2003

This study was to evaluate and to compare the compressive strength and the displacement effecting the abutment or the residual ridge which are transformed by the angle and the heights of the konus denture inner crown when restorating the unilateral konus denture by using the mandibular canine and the 1st premolar as an abutment. The author made 9 different models for different inner crown heights and konus angles. The inner crown height were divided to 5mm, 6mm, and 7mm and konus angles was divided to $4^{\circ}$, $6^{\circ}$, and $8^{\circ}$. And then in each model, 5kg of $15^{\circ}$ mesial load was stressed on the central fossa of the 1st premolar and the 1st molar. The stresses and displacement were measured using the finite element analysis. The results were as follows 1. The maximum compressive strength was shown on the connective area of the abutment and the denture base. 2. As the angle of the inner crown becomes increased, the compressive strength was shown smaller. 3. As the height of the inner crown becomes increased, the maximum compressive strength was shown smaller while the compressive strength of the root apex and the residual ridge showed larger. 4. When the stress was loaded only on the 1st premolar, the more compressive strength was concentrated on the root apex area of the 1st premolar. 5. When the stress was loaded only on the 1st premolar, the compressive strength was concentrated uniformly on the abutment and the residual ridge. 6. When the stress was loaded only on the 1st molar, the maximum displacement was shown on the distal part of the residual ridge.

• Journal of the Korean Ceramic Society
• /
• v.50 no.1
• /
• pp.82-86
• /
• 2013

A poled lead zirconate titanate (PZT) cube specimen is subjected to impulse-type compressive stress with increasing magnitude in parallel to the poling direction at four room and high temperatures. During the ferroelastic domain switching induced by the compressive stress, electric displacement in the poling direction and longitudinal and transverse strains are measured. Using the measured responses, linear material properties, namely, the piezoelectric and elastic compliance coefficients, are evaluated by a graphical method, and the effects of stress and temperature are analyzed. Finally, the dependency of the evaluated linear material properties on relative remnant polarization is analyzed and discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.5
• /
• pp.42-49
• /
• 2013

In this study, in order to analyze the crack retardation behaviors, effective plastic zone concept was proposed. By use of the proposed concept, crack retardation period, compressive residual stress and variation of effective plastic zone shapes were obtained. The results were compared with those of Willenborg model. Retardation period, compressive residual stress and effective plastic zone size obtained by using effective plastic zone concept were larger then the results obtained by using Willenborg analysis. Effective stress intensity factors obtained by using effective plastic zone concept were smaller then the results obtained by using Willenborg analysis.

• Computers and Concrete
• /
• v.22 no.1
• /
• pp.11-25
• /
• 2018

A numerical approach for the evaluation of the flexural response of Steel Fibrous Concrete (SFC) cross-sections with arbitrary geometry, with or without conventional steel longitudinal reinforcing bars is proposed. Resisting bending moment versus curvature curves are calculated using verified non-linear constitutive stress-strain relationships for the SFC under compression and tension which include post-peak and post-cracking softening parts. A new compressive stress-strain model for SFC is employed that has been derived from test data of 125 stress-strain curves and 257 strength values providing the overall compressive behaviour of various SFC mixtures. The proposed sectional analysis is verified using existing experimental data of 42 SFC beams, and it predicts the flexural capacity and the curvature ductility of SFC members reasonably well. The developed approach also provides rational and more accurate compressive and tensile stress-strain curves along with bending moment versus curvature curves with regards to the predictions of relevant existing models.

• Journal of the Korean Society for Heat Treatment
• /
• v.17 no.6
• /
• pp.336-341
• /
• 2004

The effect of shot peening conditions on the fatigue properties of heat-treated spring steel has been investigated by using residual stress measurement and metallography. The mechanical properties of material did not change so much by shot peening. However, the fatigue strength and fatigue life increased about 20% to 40% by 1-step and 2-step shot peening process. The fatigue strength and life were closely related to the value and position of maximum compressive residual stress by shot peening process. In the case of warm shot peening, compressive residual stress of specimens shot peening processed at $200^{\circ}C$ was higher than those of specimens shot peening processed at room temperature, $100^{\circ}C$ and $300^{\circ}C$.

• Economic and Environmental Geology
• /
• v.8 no.4
• /
• pp.203-210
• /
• 1975

The engineering properties of some Gyeongsang sedimentary rocks with respect to the grain size and the orientation of bedding planes were studied. The suitability of the rocks for civil and architectural construction was also investigated. The porosity of the rocks increases in proportion to the grain size. The ratio of the strain due to stress perpendicular to the bedding planes to the strain resulting from stress parallel to the bedding planes increases as the grain size decreases. The study indicates however, that the ratio of Young's modulus due to stress perpendicular to the bedding planes to Young's modulus resulting from stress parallel to the bedding planes increases in proportion to the grain size. The compressive strength of the sandstones studied is much greater than the strength of the conglomerate or shale. Only the coarse grained sandstone can be used for civil and architectural construction, regardless of the orientation of bedding planes. The relationships between compressive strength and density, elasticity and porosity, and compressive strength and mineral content were also studied.