• Structural Engineering and Mechanics
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• v.53 no.1
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• pp.159-172
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• 2015

This paper is concerned with effects of the wall flexibility on the seismic behavior of ground-supported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literature to determine the dynamic pressure stemming from the bulk material assume silo structure as rigid. However, it is expected that the horizontal dynamic material pressures can be modified due to varying horizontal extensional stiffness of the bulk material which depends on the wall stiffness. In this study, finite element analyses were performed for six different slenderness ratios according to both rigid and flexible wall approximations. A three dimensional numerical model, taking into account bulk material-silo wall interaction, constituted by ANSYS commercial program was used. The findings obtained from the numerical analyses were discussed comparatively for rigid and flexible wall approximations in terms of the dynamic material pressure, equivalent base shear and bending moment. The numerical results clearly show that the wall flexibility may significantly affects the characteristics behavior of the reinforced concrete (RC) cylindrical silos and magnitudes of the responses under strong ground motions.

• The Journal of Engineering Geology
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• v.24 no.2
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• pp.261-271
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• 2014

An almost permanent anchor (friction type) is resistant to ground deformation due to the friction between the soil and grout at a fixed length from the anchor body. The purpose of this study is to calculate the force of bearing resistance for a bearing anchor in enlarged boreholes. We conducted analytical and numerical analyses, along with laboratory testing, to find the quantities of bearing resistance prior to grouting in EBA (Enlarged Bearing Anchor) construction. The force of bearing resistance from the analytical method was defined as a function of general borehole diameter, expanded borehole diameter, and soil unconfined compressive strength. We also employed the Flac 3D finite difference numerical modeling code to analyze the bearing resistance of the soil conditions. We then created a laboratory experimental model to measure bearing resistance and carried out a pull-out test. The results of these three analyses are presented here, and a regression analysis was performed between bearing resistance and uniaxial compression strength. The laboratory results yield the strongest bearing resistance, with reinforcement 28.5 times greater than the uniaxial compression strength; the analytical and numerical analyses yielded values of 13.3 and 9.9, respectively. This results means that bearing resistance of laboratory test appears to be affected by skin friction resistance. To improve the reliability of these results, a comparison field study is needed to verify which results (analytical, numerical, or laboratory) best represent field observations.

• The Journal of Korean Association of Computer Education
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• v.15 no.2
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• pp.67-73
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• 2012

The analytical experiments for fluid dynamics lead a sequence of complex scientific computations composing of numerical equations and require enormous computing resources with appropriate management tools. Currently most studies on e-Science environment for numerical studies focus on solving specific problems to drag out the best performance of matters and have less interest in providing a common framework to apply for diverse numerical domains in engineering education, especially for fluid dynamics. This paper presents an integrated e-Science experiment tool which could be easily applicable to solve various numerical analyses in fluid dynamics. As a proof-of-concept, an integrated e-Science framework with three numerical analyses has been designed and implemented over UNICORE that runs over grid computing environment.

• Steel and Composite Structures
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• v.31 no.5
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• pp.489-502
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• 2019

This article presents a unified mathematical model to investigate free and forced vibration responses of perforated thin and thick beams. Analytical models of the equivalent geometrical and material characteristics for regularly squared perforated beam are developed. Because of the shear deformation regime increasing in perforated structures, the investigation of dynamical behaviors of these structures becomes more complicated and effects of rotary inertia and shear deformation should be considered. So, both Euler-Bernoulli and Timoshenko beam theories are proposed for thin and short (thick) beams, respectively. Mathematical closed forms for the eigenvalues and the corresponding eigenvectors as well as the forced vibration time response are derived. The validity of the developed analytical procedure is verified by comparing the obtained results with both analytical and numerical analyses and good agreement is detected. Numerical studies are presented to illustrate effects of beam slenderness ratio, filling ratio, as well as the number of holes on the dynamic behavior of perforated beams. The obtained results and concluding remarks are helpful in mechanical design and industrial applications of large devices and small systems (MEMS) based on perforated structure.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.2
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• pp.95-101
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• 2018

Diagonally reinforced concrete coupling beams (DRCB) play an important role in coupled shear wall systems since these elements dissipate most of seismic input energy under earthquake loading. For reliable seismic performance evaluation using nonlinear response history analysis, it is important to use an accurate analytical model for DRCBs. In this study, the Pinching4 model is used as a base model to simulate the cyclic behavior of DRCBs. For simulating the cyclic behavior of DRCBs using the Pinching4 model, the analytical parameters for backbone curve, pinching and cyclic deterioration in strength and stiffness should be computed. To determine the proper values of the constituent analytical parameters efficiently and accurately, this study proposes the empirical equations for the analytical parameters using regression analyses. It is shown that the hysteretic behavior of coupling beams can be simulated efficiently and accurately using the proposed numerical model with the proposed empirical equations of model parameters.

• Structural Engineering and Mechanics
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• v.38 no.5
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• pp.549-571
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• 2011

This paper presents analytical solutions for skewed thick plates under transverse loading that have previously been unreported in the literature. The thick plate solution is obtained in a framework of an oblique coordinate system. The governing equation is first derived in the oblique coordinate system, and the solution is obtained using deflection and rotation as partial derivatives of a potential function developed in this research. The solution technique is applied to three illustrative application examples, and the results are compared with numerical solutions in the literature and those derived from the commercial finite element analysis package ANSYS 11. These results are in excellent agreement. The present solution may also be used to model skewed structures such as skewed bridges, to facilitate efficient routine design or evaluation analyses, and to form special elements for finite element analysis. At the same time, the analytical solution developed in this research could be used to develop methods to address post-buckling and dynamic problems.

• International Journal of Railway
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• v.1 no.1
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• pp.6-11
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• 2008

This paper presents a performance characteristic analysis methodology for a linear induction motor used for a lightweight train. In general, an analytical method cannot provide accurate results in a linear motor because of large airgap, end effect, transverse edge effect, 3-dimensional configurations, large leakage, and so on. Besides, a numerical method requires lots of memory and solving time for transient analysis. However, the suggested methodology which is a kind of hybrid solution with an analytical method and a numerical method is very fast and accurate. Based on the methodology, 3-D FEM analyses for various design schemes of the secondary reaction plate have been done and from the analysis results, the best configuration for an urban railway transit is chosen.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.231-233
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• 2001

This paper describes an analytical solution of the voltage commands for instantaneous torque control of an I.M. The analytical solution is expressed as a simple explicit function of the instantaneous torque commands and motor speed. On the basis of the derived analytical solution, the maximum torque change rate of an I.M with a limited voltage-source is analyzed, and also the dynamic influence of rapid changes in motor speed on output torque derivations is investigated. The detailed results of these two analyses are approximated here in term of first-order linear differential equations, and their validities are confirmed through the demonstrative numerical simulations. This paper includes the simulation results of the instantaneous torque control with varied motor parameters for sensitivity analysis.

• Geomechanics and Engineering
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• v.7 no.1
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• pp.105-131
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• 2014

In this paper, the effects of variability of smear zone characteristics induced by installation of prefabricated vertical drains on the preloading design are investigated employing analytical and numerical approaches. Conventional radial consolidation theory has been adopted to conduct analytical parametric studies considering variations of smear zone permeability and extent. FLAC 2D finite difference software has been employed to conduct the numerical simulations. The finite difference analyses have been verified using three case studies including two embankments and a large-scale laboratory consolidometer with a central geosynthetic vertical drain. A comprehensive numerical parametric study is conducted to investigate the influence of smear zone permeability and extent on the model predictions. Furthermore, the construction of the trial embankment is recommended as a reliable solution to estimate accurate smear zone properties and minimise the post construction settlement. A back-calculation procedure is employed to determine the minimum required waiting time after construction of the trial embankment to predict the smear zone characteristics precisely. Results of this study indicate that the accurate smear zone permeability and extent can be back-calculated when 30% degree of consolidation is obtained after construction of the trial embankment.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.666-675
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• 2002

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate effective properties of fiber composites were extended to apply to the PFPMIDE model. The new model was validated when compared with available experimental data and other analytical results. To see the structural responses of a composite plate integrated with the PFPMIDE, three-dimensional finite element formulations were derived. Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.