• Earthquakes and Structures
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• 제14권1호
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• pp.85-94
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• 2018

The paper focuses on the seismic responses of a hyperbolic cooling tower resting on soil foundation represented by the three-parameter Vlasov elastic soil model. The three-parameter soil model eliminates the necessity of field testing to determine soil parameters such as reaction modulus and shear parameter. These parameters are calculated using an iterative procedure depending on the soil surface vertical deformation profile in the model. The soil and tower system are modeled in SAP2000 structural analysis program using a computing tool coded in MATLAB. The tool provides a two-way data transfer between SAP2000 and MATLAB with the help of Open Application Programming Interface (OAPI) feature of SAP2000. The response spectrum analyses of the tower system with circular V-shaped supporting columns and annular raft foundation on elastic soil are conducted thanks to the coded tool. The shell and column forces and displacements are presented for different soil conditions and fixed raft base condition to investigate the effects of soil-structure interaction. Numerical results indicate that the flexibility of soil foundation leads to an increase in displacements but a decrease in shell membrane and column forces. Therefore, it can be stated that the consideration of soil-structure interaction in the seismic response analysis of the cooling tower system provides an economical design process.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1513-1523
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• 2017

Improvement of numerical analysis methods has been required to solve complicated phenomena that occur in nuclear facilities. Particularly, fluid-structure interaction (FSI) behavior should be resolved for accurate design and evaluation of complex reactor vessel internals (RVIs) submerged in coolant. In this study, the FSI effect on dynamic characteristics of RVIs in a typical 1,000 MWe nuclear power plant was investigated. Modal analyses of an integrated assembly were conducted by employing the fluid-structure (F-S) model as well as the traditional added-mass model. Subsequently, structural analyses were carried out using design response spectra combined with modal analysis data. Analysis results from the F-S model led to reductions of both frequency and Tresca stress compared to those values obtained using the added-mass model. Validation of the analysis method with the FSI model was also performed, from which the interface between the upper guide structure plate and the core shroud assembly lug was defined as the critical location of the typical RVIs, while all the relevant stress intensities satisfied the acceptance criteria.

• Journal of Mechanical Science and Technology
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• 제15권3호
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• pp.366-373
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• 2001

A numerical analysis of shock wave/boundary layer interaction in transonic/supersonic axial flow compressor cascade has been performed by using a characteristics upwind Navier-Stokes method with various turbulence models. Two equation turbulence models were applied to transonic/supersonic flows over a NACA 0012 airfoil. The results are superion to those from an algebraic turbulence model. High order TVD schemes predicted shock wave/boundary layer interactions reasonably well. However, the prediction of SWBLI depends more on turbulence models than high order schemes. In a supersonic axial flow cascade at M=1.59 and exit/inlet static pressure ratio of 2.21, k-$\omega$ and Shear Stress Transport (SST) models were numerically stables. However, the k-$\omega$ model predicted thicker shock waves in the flow passage. Losses due to shock/shock and shock/boundary layer interactions in transonic/supersonic compressor flowfields can be higher losses than viscous losses due to flow separation and viscous dissipation.

• Interaction and multiscale mechanics
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• 제5권2호
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• pp.91-104
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• 2012

There is relatively little numerical study on the behavior of eccentrically loaded high strength rectangular concrete-filled steel tubular (CFST) slender beam-columns with large depth-to-thickness ratios, which may undergo local and global buckling. This paper presents a multiscale numerical model for simulating the interaction local and global buckling behavior of high strength thin-walled rectangular CFST slender beam-columns under eccentric loading. The effects of progressive local buckling are taken into account in the mesoscale model based on fiber element formulations. Computational algorithms based on the M$\ddot{u}$ller's method are developed to obtain complete load-deflection responses of CFST slender beam-columns at the macroscale level. Performance indices are proposed to quantify the performance of CFST slender beam-columns. The accuracy of the multiscale numerical model is examined by comparisons of computer solutions with existing experimental results. The numerical model is utilized to investigate the effects of concrete compressive strength, depth-to-thickness ratio, loading eccentricity ratio and column slenderness ratio on the performance indices. The multiscale numerical model is shown to be accurate and efficient for predicting the interaction buckling behavior of high strength thin-walled CFST slender beam-columns.

• Structural Engineering and Mechanics
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• 제77권5호
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• pp.627-635
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• 2021

The speed of rail vehicles become higher and higher over two decades, and China has unveiled a prototype high-speed train in October 2020 that has been able to reach 400 km/h. At such high speeds, wheel-rail force items that had previously been ignored in common computational model should be reevaluated and reconsidered. Aiming at this problem, a new model for investigating the vehicle-bridge interaction at high moving speed is proposed. Comparing with the common model, the new model was more accurate and applicable, because it additionally considers the second-order pseudo-inertia forces effect and its modeling equilibrium position was based on the initial deformed curve of bridge, which could include the influences of temperature, pre-camber, shrinkage and creep deformation, and pier uneven settlement, etc. Taking 5 km/h as the speed interval, the dynamic responses of the classical vehicle-bridge system in the speed range of 5 km/h to 400 km/h are studied. The results show that ignoring the second-order pseudo-inertia force will underestimate the dynamic response of vehicle-bridge system and make the high-speed railway bridge structure design unsafe.

• Steel and Composite Structures
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• 제46권6호
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• pp.857-865
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• 2023

This study aimed to develop a seismic retrofit technique using a steel frame which can be easily transported and assembled on site. This enables the retrofit steel frame to be easily attached to an existing structure minimizing the unwanted gap between the structure and the steel frame assembly. A one-story one-bay RC frame was tested with and without seismic retrofit using the proposed steel frame to verify the seismic retrofit effect of the proposed system, and an analysis model was developed in Opensees for seismic performance evaluation of a case study soft first-story model structure retrofitted with the developed steel frame assembly. Seismic performance of the model structure was also evaluated considering soil structure interaction effect. The experimental study confirmed that the proposed seismic retrofit system can be applied effectively to improve the seismic performance of framed structures. Time history analysis results of the model structure showed that the proposed steel frame assembly was effective in increasing the seismic load resisting capacity of the soft first-story structure. However more steel frame assemblies were required to satisfy the given performance limit state of the model structure located on weak soil due to the negative soil-structure interaction effect.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.303-306
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• 2007

CWR(Continuous Welded Rail) and bridge interaction produce rail force, bridge displacement and rail/bridge relative displacement. Each of these has limitation by many codes. In this paper, analysis of interaction has been carried out by using foreign codes(UIC 774-3 R code of Europe etc.) because there is no code about interaction between rail and bridge in Korea. Recently, railway bridges with CWR has been constructed for structural and economical reasons. When designer plans railway bridges, design a bridge model first and then investigate railway forces and displacement by interaction analysis. If these results go out bounds from limitation, designer plans railway bridges again and again. In this paper, using the parametric study on CWR and railway bridge interaction, railway bridge parameters such as length of bridge span, area of bridge, moment of inertia, stiffness of pier, etc. are presented. It helps preliminary design of railway bridges.

• Interaction and multiscale mechanics
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• 제4권2호
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• pp.155-164
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• 2011

The lattice strain evolution within polycrystalline solids is influenced by the crystal orientation and grain interaction. For multi-phase polycrystals, due to potential large differences in properties of each phase, lattice strains are even more strongly influenced by grain interaction compared with single phase polycrystals. In this research, the effects of the grain interaction and crystal orientation on the lattice strain evolution in a two-phase polycrystals are investigated. Duplex steel of austenite and ferrite phases with equal volume fraction is selected for the analysis, of which grain arrangement sensitivity is confirmed in the literature through both experiment and simulation (Hedstr$\ddot{o}$m et al. 2010). Analysis on the grain interaction is performed using the results obtained from the finite element calculation based on the model of restricted slip within crystallographic planes. The dependence of lattice strain on grain interactions as well as crystal orientation is confirmed and motivated the need for more in-depth analysis.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1460-1465
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• 2007

CWR(Continuous Welded Rail) and bridge interaction produce rail force, bridge displacement and rail/bridge relative displacement. Each of these has limitation by many codes. In this paper, analysis of interaction has been carried out by using foreign codes(UIC 774-3 R code of Europe etc.) because there is no code about interaction between rail and bridge in Korea. Recently, railway bridges with CWR has been constructed for structural and economical reasons. When designer plans railway bridges, design a bridge model first and then investigate railway forces and displacement by interaction analysis. If these results go out bounds from limitation, designer plans railway bridges again and again. In this paper, using the parametric study on CWR and railway bridge interaction, railway bridge parameters such as length of bridge span, area of bridge, moment of inertia, stiffness of pier, etc. are presented. It helps preliminary design of railway bridges.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.445-450
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• 2007

CWR(Continuous Welded Rail) and bridge interaction produce rail force, bridge displacement and rail/bridge relative displacement. Each of these has limitation by many codes. In this paper, analysis of interaction has been carried out by using foreign codes(UIC 774-3 R code of Europe etc.) because there is no code about interaction between rail and bridge in Korea. Recently, railway bridges with CWR has been constructed for structural and economical reasons. When designer plans railway bridges, design a bridge model first and then investigate railway forces and displacement by interaction analysis. If these results go out bounds from limitation, designer plans railway bridges again and again. In this paper, using the parametric study on CWR and railway bridge interaction, railway bridge parameters such as length of bridge span, area of bridge, moment of inertia, stiffness of pier, etc. are presented. It helps preliminary design of railway bridges.