• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.165-165
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• 1990

This study focuses the mechanical deformation response predicted by the plasticity model for polycrystalline ice. To describe various deformation characteristics, ice is idealized as a perfectly plastic material using an asymptotic exponential failure criterion. This criterion is suite for describing materials which exhibit brittle deformation at low hydrostatic pressure and ductile deformation at high hydrostatic pressure. The results are compared to those of continuum damage mechanics model. Plasticity model shows good agreement with damage model and experimental results for high confining pressures even at high strain-rates which is usually considered as a brittle condition under uniaxial compression.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.173-181
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• 2006

Many isolated bridges are designed and constructed after the introduction of the seismic design. However those bridges designed in engineering fields have unnecessarily high serviceability limit and brittle failure mechanism, which do not satisfy the seismic design concept. Such design results are due to the excessive substructure stiffness of the conventional design method as well as the misunderstanding of the seismic design method. In this study an isolated bridge designed with the conventional design method is selected and the same bridge with steel bearings is modelled for the comparative seismic design. From the comparison, the seismic design procedures satisfying the required performance levels are provided for the two bridges. It is confirmed that the isolated bridge requires more complicated design procedure with trial and error methods and reanalyses but provides higher serviceability limit compared to the bridge with steel bearings. However, because the required serviceability limit can also be obtained by adjusting substructure stiffness, it is a resonable seismic design process that an isolated bridge is to be considered as an alternative design when the ductile failure mechanism is not obtained with a bridge with steel bearings.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.95-104
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• 2013

Recently, application of CSG is increasing in various design construction projects. At the initial stage of cementation CSG materials show the same mechanical characteristics as soil, however, as the cementation process develops, CSG materials gradually reveal material characteristics of concrete. The hardened CSG manifests elastic behavior such as maximum strength at small strain range and rapid brittle failure. In this research, PVA fiber stiffeners were used in order to: (1) reduce such brittle behavioral characteristics; (2) improve the relatively weak tension performance of CSG materials. The binding strength between the bed materials and fiber prevents rapid brittle failure and increases tensional strength of fiber reinforced CSG materials.Test results show that fiber reinforcement alone could induce the stress-strain characteristics of CSG materials from brittle failure to ductile failure and also increase the residual strength.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.42-46
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• 1998

Miniaturized specimen technology Permits mechanical behavior to be determined using a minimum volume of material. The technology is useful in case of not collecting a large amount of materials from industrial equipments. Five kinds of accelerated degradation materials were prepared by isothermal aging heat treatment at $630^{\circ}C$. Three kinds of specimens were prepared for impact testing. In order to increase plastic constraint of subsize specimen, side-groove was introduced. Results between subsize and full size impact testing were compared. Size effects correlations were developed for the impact properties of turbine rotor material. These correlations successfully predict the ductile brittle transition temperature (DBTT) of full size Charpy impact specimens based on subsize specimen data.

• Geomechanics and Engineering
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• v.24 no.2
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• pp.157-166
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• 2021

This paper aims at the temperature and slenderness ratio effects on physical and mechanical properties of Beishan granite. A series of uniaxial compression tests with various slenderness ratios and temperatures were carried out, and the acoustic emission signal was also collected. As the temperature increases, the fracture aperture of intercrystalline cracks gradually increases, and obvious transcrystalline cracks occurs when T > 600℃. The failure patterns change from tensile failure mode to ductile failure mode with the increasing temperature. The elastic modulus decreases with the temperature and increases with slenderness ratio, then tends to be a constant value when T = 1000℃. However, the peak strain has the opposite evolution as the elastic modulus under the effects of temperature and slenderness ratio. The uniaxial compression strength (UCS) changes a little for the low-temperature specimens of T < 400℃, but a significant decrease happens when T = 400℃ and 800℃ due to phase transitions of mineral. The evolution denotes that the critical brittle-ductile transition temperature increases with slenderness ratio, and the critical slenderness ratio corresponding to the characteristic mechanical behavior tends to be smaller with the increasing temperature. Additionally, the AE quantity also increases with temperature in an exponential function.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.577-580
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• 2004

Recently, DFRCCs (Ductile Fiber Reinforced Cementitious Composites), materials with remarkable ductility when compared to ordinary fiber-reinforced concrete (FRC), have been developed and studied actively in the US, Japan, and many European countries. The transformation of failure behavior from brittle to ductile is achieved by incorporating with fracture mechanics concept especially micro-mechanical models approach of cementitious composite materials in manufacturing ordinary fiber-reinforced composites. The purpose of this study is to accurately understand the shear behavior of DFRCC repaired RC beams. Using a four-point bending test, the shear strengths and shear stress-deflection relations of DFRCC repaired RC specimens are obtained. The results show that DFRCC can be effectively used for repairing materials for concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.567-572
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• 1998

Structural behavior of R/C deep beams was investigated and compared to those of specimens with CFRP Grids. Test results show that the crushing of compression strut for the unstrengthened R/C deep beams is changed to the group of several diagonal cracks at mid-depth within the sheat span. Strengthened specimens grow to be more ductile after the redistribution of internal force on the CFRP Grids. The failure mode and variations of strains in the specimens are dependent on the shear span-to-depth ratio. The lower the shear span-to-depth ratio, the bigger failure load and the less variations in strain are observed. Additional anchorage of CFRP Grids does not only cause the improvement in the internal resistance, but also control the brittle shear failure of specimen after reaching the maximum loads.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.293-298
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• 2003

In this study, tensile adhesive strength(TAS) test was carreid out for evaluated the effects of temperature conditions(-20, -10, 5, 20, 30, $40^{\circ}C$) on the tensile adhesive characteristics about six waterproofing membranes which were commercially used in bridge decks. And, failure appeariences of waterproofing systems in each temperature were investigated and observed the sawing surfaces of waterproofing systems for whether or not damaged of waterproofing membranes. TAS test results were increased when test temperature was decrease in all waterproofing membrane. The type of failure was ductile in $30^{\circ}C$ and $40^{\circ}C$, but brittle failure below $20^{\circ}C$. This results were shown that if temperature above $30^{\circ}C$ is continued for a long time, waterproofing material will be damaged by softening and a part of membranes were damaged by hot aggregate in SMA. So we will consider the type of asphalt for choice of the waterproofing membranes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.109-116
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• 2010

Three-dimensional finite element model for analysis of reinforced concrete members was developed in order to investigate the prediction of bending and shear failure of reinforced concrete beams. A failure surface of concrete in strain space was newly proposed in order to predict accurately the ductile response of concrete under multi-axial confining stresses. Cracking of concrete in triaxial state was incorporated with considering the tensile strain-softening behavior of cracked concrete as well as the cracked shear behavior on cracked surface of concrete caused by aggregate interlocking and, dowel action. By correlation study on failure types of bending and shear of beams, current finite element model was well simulated not only the type of ductile bending failure of under-reinforced beams but also the type of brittle shear failure of no-stirruped reinforced concrete beam.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.143-153
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• 2003

New strengthening method based on Near Surface Mounted technique (NSM) is suggested, which can overcome the brittle nature of failure inherent to those reinforced concrete beams strengthened with FRP composite materials. The suggested technique secures ductile failure of reinforced concrete beams by having the strengthening Hybrid FRP rebars unbonded in parts. Experiments were performed in order to compare structural behaviors of strengthened beams with and without unbending along the Hybrid FRP rebars. Test results showed that only those beams strengthened by partially unbonded NSM failed in ductile manner. Theoretical expressions were derived for the minimum unbonded length of Hybrid FRP rebars with which ultimate strength of the reinforced concrete beam with partially unbonded NSM could be reached. The suggested partially unbonded NSM technique is expected to significantly improve the structural behavior of the strengthened beam with FRP composite materials.