• The Journal of the Acoustical Society of Korea
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• v.34 no.5
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• pp.360-370
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• 2015

In case that an infinite length waveguide structure is connected with a finite length structure, it is required to combine a wave approach for the waveguide structure and a modal approach for the finite length structure to investigate the dynamic response of the connected target structure. In this study, the wavenumber finite element (WFE) analysis is adopted for the infinite length waveguide substructure and a finite element (FE) method is applied for the finite length substructure and then their results are coupled in terms of the impedance or mobility at the connected points between the substructures. As a structural model, an infinite length cylindrical shell with a rectangular plate inside is regarded. These two substructures are connected at the four corner points of the plate, rigidly or resiliently. From this investigation, it was confirmed that the wave approach (WFE method) and modal approach (FE method) can be combined by the impedance coupling.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.47-58
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• 2012

Dynamic behaviors of a corrugated steel plate tunnel lining system are examined under wind loads due to passing vehicles. Applied wind loads are simulated by applying the time functions as a vehicle moves through the tunnel. Wind loads are described by the pressure and suction as a vehicle arrives and leaves target positions in the tunnel. The tunnel lining is modeled using the simplified shell elements that retain the characteristics of the corrugated shapes. The displacements of the tunnel lining are evaluated under various conditions regarding wind velocity and the passing vehicles. The responses are found to increase as the vehicle velocity and wind velocity increase. A maximum displacement of 25mm occurs when two vehicles are crossing at the speed of 120km/h. A row of vehicles running consecutively minimally affects the dynamic responses with less than 2.5% of the dynamic responses enlarged and attributed to one running vehicle. It should be noted that the dynamic responses of the tunnel lining should be considered when there is no shotcrete applied.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.141-150
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• 2005

The behavior of the concrete slabs-on-grade considering the horizontal resistance at the slab bottom, which exists due to the shear resistance of the foundation and the friction between the slab and the foundation, has been investigated when the slabs-on-grade are subjected to the vertical load. Analytical formulations have been developed to include the effect of the horizontal resistance at the slab bottom, and the solutions have been obtained in the transformed field domain using the Fourier transform. Finite element formulations have also been developed using the plate bending elements and the flat shell elements. The solutions from the analytical and numerical models have been compared and showed very good agreement. The sensitivity of the horizontal resistance to the stresses of the concrete slab has been investigated with various values of the slab thickness, elastic modulus, and vertical stiffness of the foundation. The analysis results show that the horizontal resistance at the plate bottom can significantly affect the stresses of the slab.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.145-152
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• 2011

Current Bridge Specification for Highway Bridges adopts a simplified method to determine sectional forces of abutment wing by dividing its area into four sections. This simplified method was developed in Japan when numerical analysis was not mature and computer resources were expensive. This simplified method has been with us without modification. This study evaluates the problem of current design practice to improve the design guideline for abutment wing. In this study, a finite element model of abutment wing based on shell elements was developed to obtain accurate sectional force. In addition, foreign design specifications regarding abutment wing were thoroughly examined. It has been observed that sectional forces obtained from the simplified method produce inaccurate results under various geometric shapes. Thus, it is recommended that two dimensional plate analyses should be adopted for future design of abutment wing wall.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.373-380
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• 2014

Film flows applied to shell-and-tube heat exchangers in various industrial fields have been studied for a long time. One boundary of the film flow interfaces with a fixed wall, and the other boundary interfaces with a gaseous region. Thus, the flows become so unstable that wavy behaviors are generated on free surfaces as the film Reynolds number increases. First, high-amplitude solitary waves are detected in a low Reynolds number laminar region; then, the waves transit to a low-amplitude, high frequency ripple in a turbulent region. Film thickness is the most significant factor governing heat transfer. Since the wave accompanied in the film flow results in temporal and spatial variations in film thickness, it can be of importance for numerically predicting the film's wavy behavior. In this study, various turbulent models are applied for predicting low-amplitude ripple flows in turbulent regions. The results are compared with existing experimental results, and finally, the applied turbulent models are appraised in from the viewpoint of wavy behaviors.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.17-25
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• 1998

Aluminum alloys have low density, relatively high strength and yield strength, good plasticity, good machinability, and high corrosion and acid resistance. Therefore, they are suitable for large containers for the food, chemical and other industries. Large containers are often bodies of revolution consisting of shell courses, stiffening rings, heads and other elements joined by annular welds. Larger containers have longer welds and require greater leak-tightness and higher weld mechanical properties. The LNG tank consists of aluminum plates with various sizes, so its construction should by divided by several sections. Moreover, each section has its own sub-section consisted of several aluminum plates. To guarantee the quality of huge LNG tank, therefore, the precise control of plate dimension should by urgently needed in conjunction with the appropriate selection of process parameters such as cutting speed, depth of cut, rotational speed and so on. In this paper, a manufacturing system was developed to implement automatic circular tracking in height direction and automatic circular interpolation in depth of cut direction. Also, the neural network based on the backpropagation algorithm was used to predict the cutting quality and motor load related with the life time of the developed system. It was revealed that the manufacturing system and the neural network could be effectively applied to the bevelling process and to predict the quality of machined area and the motor load.

• Geotechnical Engineering
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• v.13 no.4
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• pp.163-176
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• 1997

It has long been recognized that the H-beam steel rib has many shortcomings when used as a steel support in tunneling. One of the major shortcomings is the shotcrete shadow created behind H-beam flange which eventually reduces the load bearing capacity of shotcrete shell. In many European countries, plate girder as the H-beam steel rib has been replaced by lattice girder which has many advantages over the H-beam steel rib. Successful application of the lattice girder as a steel support requires a thorough investigation on the load bearing capacity of the lattice girder. Therefore, laboratory bending and compression tests were conducted on lattice girders with the aim of investigating the load bearing capacity of the lattice girders. The results of tests show that the load bearing capacity of laIn twice girders is higher than that of H-beams, which indicates that the lattice girder can be effectively used as a support in tunneling.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.267-274
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• 2010

Unlike the structure which has a homogeneous material property, a composite structure is coupled with materials which have different properties, namely, steel and concrete. At actual modeling, the real behavior cannot be predicted without consideration of those material characteristics. Therefore, by putting the interface element between concrete and steel, a slip of steel and concrete is made predictable. Interface element can be used properly not by an ordinary constitutive relation, but by a non-linear constitutive relation considering actual adhesion and slip. A contact surface between plate-shape steel box and concrete is described by using this interface element. Furthermore, because the general 8 node conforming element is inappropriate for describing a bending buckling behavior of steel box, the EAS(Enhanced Assumed Strain) solid-shell element is used to describe a bending behavior of plate-shape steel box.

• Steel and Composite Structures
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• v.20 no.1
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• pp.167-184
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• 2016

This paper presents the details of Finite Element (FE) analysis carried out to determine the limiting deformation capacity and failure mode of Laced Steel-Concrete Composite (LSCC) beam, which was proposed and experimentally studied by the authors earlier (Anandavalli et al. 2012). The present study attains significance due to the fact that LSCC beam is found to possess very high deformation capacity at which range, the conventional laboratory experiments are not capable to perform. FE model combining solid, shell and link elements is adopted for modeling the beam geometry and compatible nonlinear material models are employed in the analysis. Besides these, an interface model is also included to appropriately account for the interaction between concrete and steel elements. As the study aims to quantify the limiting deformation capacity and failure mode of the beam, a suitable damage model is made use of in the analysis. The FE model and results of nonlinear static analysis are validated by comparing with the load-deformation response available from experiment. After validation, the analysis is continued to establish the limiting deformation capacity of the beam, which is assumed to synchronise with tensile strain in bottom cover plate reaching the corresponding ultimate value. The results so found indicate about $20^{\circ}$ support rotation for LSCC beam with $45^{\circ}$ lacing. Results of parametric study indicate that the limiting capacity of the LSCC beam is more influenced by the lacing angle and thickness of the cover plate.

• Structural Engineering and Mechanics
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• v.49 no.6
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• pp.705-726
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• 2014

In general, cylindrically curved plates are used in ships and offshore structures such as wind towers, spa structures, fore and aft side shell plating, and bilge circle parts in merchant vessels. In a number of studies, it has been shown that curvature increases the buckling strength of a plate under compressive loading, and the ultimate load-carrying capacity is also expected to increase. In the present paper, a series of elastic and elastoplastic large deflection analyses were performed using the commercial finite element analysis program (MSC.NASTRAN/PATRAN) in order to clarify and examine the fundamental buckling and collapse behaviors of curved plates subjected to combined axial compression and lateral pressure. On the basis of the numerical results, the effects of curvature, the magnitude of the initial deflection, the slenderness ratio, and the aspect ratio on the characteristics of the buckling and collapse behavior of the curved plates are discussed. On the basis of the calculated results, the design formula was developed to predict the buckling and ultimate strengths of curved plates subjected to combined loads in an analytical manner. The buckling strength behaviors were simulated by performing elastic large deflection analyses. The newly developed formulations were applied in order to perform verification analyses for the curved plates by comparing the numerical results, and then, the usefulness of the proposed method was demonstrated.