• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.391-399
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• 2006

Plate girders with variable depths have been often used at piers considering not only the economy but also an aesthetic aspect. Tapered plate girders exhibit more complicated behaviors than prismatic girders especially under shear. However, a comprehensive design method for the determination of the shear strength has yet to be developed mainly due to lack of study. In this study, investigated is the buckling and ultimate behaviors of tapered plate girders subjected to shear through finite element analyses. From the analysis results, a simple design formula is suggested for the evaluation of the shear strength of tapered plate girders.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.128-136
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• 2014

It is known that the best way to recycle fly ash is to use in concrete. It is impossible to bury in the ground this fly ash recently, so it is trying to use high volume fly ash concrete. Nevertheless, recent main research topics are focused in the part of material only. However, it is necessary to perform the researches about elasticity modulus, stress-strain relationship and structural behavior. Therefore, in this paper, 18 test members were manufactured with 3 test variables, namely fly ash replacement ratio 0, 35, 50%, concrete compressive strength 20, 40, 60MPa and 2 tensile steel ratio. 18 test members were tested for flexural behavior. From the test results, there were no differences between 35, 50% high volume fly ash cement concrete and ordinary concrete without fly ash (FA=0%). In order to evaluate the HVFAC flexural behavior, Analytical model was proposed and the computer program was developed. There were no differences between test results and analysis results. So, the proposed analytical model was reasonable.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.796-805
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• 2020

Purpose: A static loading test was performed to evaluate the ultimate flexural strength of a girder in which 80MPa high-strength concrete was synthesized on the compressive flange of the I-shape steel girder. Method: This test is designed and fabricated two types of specimens with different shear-connection specifications, and evaluated their ultimate flexural behavior until reaching the extreme event limit states. In addition, the ultimate strength was evaluated by comparing the test results and the results of the strain compatibility method. Result: By confirming the displacement within 0.02mm as a result of the relative slip measurement, it was verified that the two specimens secured perfect bonding. Therefore, the difference in the shear specification does not have a great effect on the stiffness, and if the specimens are completely synthesized, there is no difference in the behavior until it reaches the extreme-event limit states. Conclusion: The girder to be tested has a working load within the elastic range and meets the usability requirements for allowable deflection. Therefore, even if a part of the casing is subjected to the tensile force at the level of cracking, the deck will first reach the compression failure due to the role of the reinforcing bar.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.456-464
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• 2016

Increasing the strength of structural materials allows their self-weight to be reduced and this, in turn, enables the structures to satisfy esthetic requirements. The yield strength of high-performance steel is almost 480 MPa, which is approximately 50% higher than that of general structural steel. The use of high strength materials, however, makes the sections more slender, which can potentially result in significant local stability problems. The strength of slender element sections might be governed by their elastic buckling behavior, and the elastic buckling strength is very sensitive to the boundary conditions. Because the web provides the boundary conditions of the compressive thin-flange, the stiffness of the web can affect the elastic buckling strength of the flange. In this study, therefore, the effects of the flange and web slenderness ratios on the elastic flange local buckling of I-girders subjected to a pure bending moment were evaluated by finite element analysis (FEA). The analysis results show that the elastic local buckling strength and buckling modes were affected not only by the web support conditions, but also by the flange and web slenderness ratios.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.617-627
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• 2011

This paper presents the results of analytical simulation of shake-table responses of a 1:5 scale 10-story reinforcement concrete(RC) residential building model by using the PERFORM-3D program. The following conclusion are drawn based on the observation of correlation between experiment and analysis; (1) The analytical model simulated fairly well the global elastic behavior under the excitations representative of the earthquake with the return period of 50 years. Under the design earthquake(DE) and maximum considered earthquake(MCE), this model shows the nonlinear behavior, but does not properly simulate the maximum responses, and stiffness and strength degradation in experiment. The main reason is considered to be the assumption of elastic slab. (2) Although the analytical model in the elastic behavior closely simulated the global behavior, there were considerable differences in the distribution of resistance from the wall portions. (3) Under the MCE, the shear deformation of wall was relatively well simulated with the flexural deformation being overestimated by 10 times that of experiment. This overestimation is presumed to be partially due to the neglection of coupling beams in modeling.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.1-12
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• 2002

To obtain more accurate responses of laminated composite structures, the effect of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate need to be considered in the analysis. The improved higher-order theory is used to determine the deflections and natural frequencies of laminated composite structures. A quasi-elastic method is used for the solution of viscoelastic analysis of the laminated composite plates and sandwiches. Solutions of simply-supported laminated composite plates and sandwiches are obtained and the results are compared with those by the 3D elasticity theory and other theories. The improved theory proposed in this paper is shown to predict the deflections and natural frequencies more accurately than all other theories.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.725-728
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• 2008

This study was to establish 3 levels of high fineness fly ash like 4000, 6000, and 8000 class and 30% replacement ratio in order to analyze mechanics and shrinkage properties of concrete by using high fineness fly ash. Furthermore, this study was to make a plan in two levels of water-binder ratio like 40% and 50%. In addition, as a result of measurement by the establishment of combined condition of ternary system as 20% replacement ratio level of three sorts of ground granulated blast furnace slag, there was a tendency to be equal or higher to the plain concrete as the fineness of fly ash increased in strength property. Simultaneously, this study had a tendency in the relationship between the compressive strength and elastic modulus that the more the fineness of fly ash, the more the elastic modulus increased a little. In addition, this study had a tendency that the more elastic modulus moved to the long-term aged one, the more it increased definitely. The effect on the fineness of fly ash remained at a low level in the drying shrinkage. This study has shown that the more the fineness increased, the more the elastic modulus decreased.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.905-911
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• 1998

Damping is a property for materials and systems to dissipate energy during periodic deformations. Generally, damping causes stiff decrease in amplitudes and shifts in phases. Also, even at resonance, amplitudes are substantially attenuated. This phenomenon of damping helps in reducing stresses developed during vibrations and consequently improves fatigue lives of materials. In this work internal damping and complex moduli are experimentally determined. An impulse technique is utilized in experiments and cantilever beams are selected as test subjects for the measurements of flextural vibrations since the beams lend themselves easily as simplistic ideal models. A resonance method is employed to determine resonance frequencies which are utilized to compute storage moduli. Also, loss moduli are evaluated from damping capacities and storage moduli. The storage and loss moduli combined yield complex moduli. Finally internal damping is evaluated from bandwidth technique, the real component of the transfer function.

• Journal of Korean Society of Steel Construction
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• v.25 no.2
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• pp.141-151
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• 2013

In this paper, lateral-torsional buckling(LTB) strength of HSB800 steel plate girder under uniform bending moment was estimated by the nonlinear analysis. Doubly symmetric sections with slender, noncompact and compact webs were considered and the LTB strength in the inelastic range was estimated by taking initial imperfection and residual stress into account. For the numerical analysis, single-panel model and three-panel model were considered and analysis of SM490 steel plate girder was performed to judge the validity of the constructed models by comparing the results with AASHTO, AISC, Eurocode and KHBDC(LSD) codes. By using the same models, LTB strength of HSB800 girder was evaluated and it was acknowledged that the current codes can be applied to HSB800 girders with doubly symmetric section in the inelastic LTB range.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.50-60
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• 2023

Ball Grid Array (BGA) is a widely used package type due to its high pin density and good heat dissipation. In BGA, solder balls play an important role in electrically connecting the package to the PCB. Therefore, understanding the inelastic deformation of solder balls under various mechanical loads is essential for the robust design of semiconductor packages. In this study, the geometrical effect on the inelastic deformation and fracture of solder balls were analyzed by finite element analysis. The results showed that fracture occurred in both tilted and hourglass shapes under shear loading, and no fracture occurred in all cases under compressive loading. However, when bending was applied, only the tilted shape failed. When shear and bending loads were combined with compression, the stress triaxiality was maintained at a value less than zero and failure was suppressed. Furthermore, a comparison using the Lagrangian-Green strain tensor of the critical element showed that even under the same loading conditions, there was a significant difference in deformation depending on the shape of the solder ball.