• Steel and Composite Structures
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• v.36 no.4
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• pp.399-415
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• 2020

Responses of semi-rigid frames having different degrees of semi-rigidity obtained by the nonlinear static analysis (NSA) are evaluated at specific target displacements by comparing them with those obtained by the nonlinear time-history analysis (NTHA) for scaled earthquakes. The peak ground accelerations (PGA) of the earthquakes are scaled such that the obtained peak top story displacements match with the target displacements. Three different types of earthquakes are considered, namely, far-field and near-field earthquakes with directivity and fling-step effects. In order to make the study a comprehensive one, three degrees of semi-rigidity (one fully rigid and the other two semi-rigid), and two frames having different heights are considered. An ensemble of five-time histories of ground motion is included in each type of earthquake. A large number of responses are considered in the study. They include the peak top-story displacement, maximum inter-story drift ratio, peak base shear, total number of plastic hinges, and square root of sum of the squares (SRSS) of the maximum plastic hinge rotations. Results of the study indicate that the nonlinear static analysis provides a fairly good estimate of the peak values of top-story displacements, inter-story drift ratio (for shorter frame), peak base shear and number of plastic hinges; however, the SRSS of maximum plastic hinge rotations in semi-rigid frames are considerably more in the nonlinear static analysis as compared to the nonlinear time history analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.284-289
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• 1993

To analyze the effects of compressive strength of concrete and longitudinal steel ratio on buckling behavior of columns, 36tied reinforced concrete columns with hinged ends were tested. The 100mm square cross section was used and the amount of eccentricity was 10mm. The compressive strengths of column specimens with slenderness ratios of 15, 30 and 50 were 202, 513 and 752 kg/$\textrm{cm}^2$. The longitudinal steel ratio of columns with bending about a section diagonal and about a principal axis were 2.85%(4-D10). The ratio of ultimate load capacity to that of short column with the same eccentricity was much decreased at high slenderness ratio with increasing the compressive strength of concrete. And the lateral displacement of column at the ultimate load was decreased as the strength was increased. These are due to that at high slenderness ratio, the load capacity and behavior of column are affected by flexural rigidity. And, it was also found that for the same quantity of confining steel and level of axis load, there is little difference between the flexural strength for bending about a section diagonal and for bending about principal axis.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.128-129
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• 2016

This study is to categorize the loading of multiple persons on a vertical building elements into three types to test the size of crowd pressure under each loading patterns. The loading patterns is divided under the combination of loading method and loading persons. The loading method is categorized into the method of instantaneous loading of hand on a force plate and the method of continuous loading. The loading persons has been composed of 1~5 persons under the loading patterns. The loading patterns is also divided into lateral loading, longitudinal loading, and agglomeration loading. The subject group has been composed of 12 males in 20s. The load measurement device(size 1800×600×36mm, capacity 20kN, rigidity 28kN/cm) has been designed and manufactured directly. To eliminate the difference of individual, the size of crowd pressure has been converted into the strength to weight ratio (maximum load/weight) for computation. The strength to weight ratio in lateral loading was about 0.91 under instantaneous loading and about 0.47 under continuous loading. The strength to weight ratio in longitudinal loading was about 0.65 under instantaneous loading and about 0.36 under continuous loading. The strength to weight ratio in agglomeration loading was about 0.65 under instantaneous loading and about 0.36 under continuous loading.

• Textile Coloration and Finishing
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• v.22 no.3
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• pp.272-281
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• 2010

This paper surveys the effects of drawing conditions of the worsted staple yarns on the mechanical properties of the knitted fabrics for highly aesthetical fabrics. The drawn worsted yarns were made on the yarn drawing system with various draw ratios under the fixed conditions of setting time, reduction and oxidation. The knitted fabric specimens were prepared on the 16 gauge circular knitting machine using these drawn worsted staple yarns. The tensile, shear, bending, compression and surface properties of these knitted fabrics were measured by KES-FB-AUTO-A system and also discussed with the drawing conditions. The tensile linearity, shear stiffness and bending rigidity decreased with increasing draw ratio. Any changes were not shown on the compressional properties with drawing conditions. But the friction coefficient of the knitted fabric on the course direction increased with increasing draw ratio, while there was no change according to the draw ratio on the wale direction.

• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.625-644
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• 2015

In this paper, a two-layer partial interaction composite beams model considering the higher order shear deformation of sub-elements is built. Then, the governing differential equations and boundary conditions for static analysis of linear elastic higher order composite beams are formulated by means of principle of minimum potential energy. Subsequently, analytical solutions for cantilever composite beams subjected to uniform load are presented by Laplace transform technique. As a comparison, FEM for this problem is also developed, and the results of the proposed FE program are in good agreement with the analytical ones which demonstrates the reliability of the presented exact and finite element methods. Finally, parametric studies are performed to investigate the influences of parameters including rigidity of shear connectors, ratio of shear modulus and slenderness ratio, on deflections of cantilever composite beams, internal forces and stresses. It is revealed that the interfacial slip has a major effect on the deflection, the distribution of internal forces and the stresses.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.5
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• pp.97-106
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• 1990

A method of weight evaluation of the load-bearing structural elements of cars is presented and the weight ratio of the analysis model is investigated. Replacing the materials of floor elements of the car into the high-strength steel, a considerable weight-reduction of the model has been obtained. The 1500cc model is selected for the present study and the stick model analysis is employed for the structural analysis. The torsional stiffness of the weight-reduced model is also evaluated and it is shown it has a reasonable rigidity. The ratio of the weight of the load-bearing structural elements to the unladen vehicle weight of cars is about 0.12for the 1500cc model and the weight-reduction of this study can be obtained around 17% of the weight of the load-bearing structural elements.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.472-476
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• 2024

It is important that radioactive and nuclear wastes are immobilized in a glass composition with lower melting temperatures due to their economy. In this study, the elastic and mechanical properties of sodium borate-based vitrified radioactive waste were measured using ultrasonic techniques. Many ultrasonic parameters, such as elastic moduli, Poisson's ratio, and microhardness, were calculated by measuring the ultrasonic velocities of the glasses. The ultrasonic velocity data, the density, the calculated elastic moduli, micro-hardness, softening temperature, and Debye temperature depending on the glass composition were evaluated, and the relation with the structure was clarified. It was observed that the elastic modulus and Poisson ratio increased as the Cs₂O content increased in glasses containing Cs waste. This result shows that the rigidity of the network structure of these glasses increases in contrast to the glass containing Sr.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.26-39
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• 1999

Bis-GMA, the representative monomer of bonding resin, contributes to the rigidity of bonding layer. Hydrophilic monomer contributes to the permeability into dentin substrates while weaken the bonding layer due to its small molecular weight. The degree of conversion also contributes to the ultimate strength of the bonding layer. This study was performed for the correlation analysis of monomer ratio and dentin bonding strength via degree of conversion. 7 experimental bonding resins were prepared with Bis-GMA, ratio from 20% to 80% by 10% increment, and hydrophilic HEMA monomer. Their degree of conversion and shear bond strength to dentin were compared with Scotchbond Multi-Purpose adhesive, and the fractured surfaces were examined microscopically. The results were as follows; 1. The degree of conversion increased when, the ratio of Bis-GMA increased from 20% to 70%, whereas it decreased when the ratio of Bis-GMA was 80%. 2. Shear bond strengths of the experimental bonding resins of 80%, 70%, 60% ratio of Bis-GMA were significantly higher than those of the experimental bonding resin of 50% ratio of Bis-GMA and Scotchbond Multi-Purpose adhesive. Lower shear bond strengths were obtained with the experimental bonding resins of 40%, 30%, 20% ratio of Bis-GMA (p<0.05). 3. Adhesive fractures were associated with the bonding resins of the lower bond strength, while cohesive fractures within the bonding resin layer were associated with the bonding resins of higher bond strength. Bonding resins with shear bond strength higher than 18MPa showed some cohesive fractures within the composite resin or within the dentin. 4. Correlations between Bis-GMA ratio and the degree of conversion (r=0.826), between Bis-GMA ratio and shear bond strength (r=0.853), and between the degree of conversion and shear bond strength (r=0.786) were significant (p<0.05).

• Geomechanics and Engineering
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• v.13 no.4
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• pp.601-619
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• 2017

Cantilever retaining wall movements generally depend on the intensity and duration of ground motion, the response of the soil underlying the wall, the response of the backfill, the structural rigidity, and soil-structure interaction (SSI). This paper investigates the effect of material properties on seismic response of backfill-cantilever retaining wall-soil/foundation interaction system considering SSI. The material properties varied include the modulus of elasticity, Poisson's ratio, and mass density of the wall material. A series of nonlinear time history analyses with variation of material properties of the cantilever retaining wall are carried out by using the suggested finite element model (FEM). The backfill and foundation soil are modelled as an elastoplastic medium obeying the Drucker-Prager yield criterion, and the backfill-wall interface behavior is taken into consideration by using interface elements between the wall and soil to allow for de-bonding. The viscous boundary model is used in three dimensions to consider radiational effect of the seismic waves through the soil medium. In the seismic analyses, North-South component of the ground motion recorded during August 17, 1999 Kocaeli Earthquake in Yarimca station is used. Dynamic equations of motions are solved by using Newmark's direct step-by-step integration method. The response quantities incorporate the lateral displacements of the wall relative to the moving base and the stresses in the wall in all directions. The results show that while the modulus of elasticity has a considerable effect on seismic behavior of cantilever retaining wall, the Poisson's ratio and mass density of the wall material have negligible effects on seismic response.

• Fibers and Polymers
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• v.7 no.3
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• pp.295-304
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• 2006

High-bulk worsted yams with different shrinkable and non-shrinkable acrylic fibers blend ratios are produced and then single jersey weft knitted fabrics with three different structures and loop lengths are constructed. The physical properties of produced yams and compression properties of produced fabrics at eight pressure values (50, 100, 200, 500, 1000, 1500 and $2000 g/cm^2$) were measured using a conventional fabric thickness tester. Then, weft-knitted fabric compression behavior was analyzed using a two parameters model. It is found that at 40 % shrinkable fibre blending ratio the maximum yam bulk, shrinkage, abrasion resistance and minimum yarn strength are obtained. It is also shown that high-bulk acrylic yarn has the highest elongation at 20 % shrinkable fibre blend ratio. The statistical regression analysis revealed that the compression behavior of acrylic weft-knitted fabrics is highly closed to two parameter model proposed for woven fabrics. It is also shown that for weft-knitted structure, there is an incompressible layer (V') which resists against high compression load. Acrylic weft-knitted fabrics with knit-tuck structure exhibit higher compression rigidity and lower softness than the plain and knit-miss structures. In addition, at 20 % shrinkable fibre blend ratio, the high-bulk acrylic weft-knitted fabrics are highly compressible.