• Earthquakes and Structures
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• v.14 no.5
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• pp.399-409
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• 2018

The dynamic response and seismic damage of single-layer reticulated shells in the near field of a rupturing fault can be different from those in the far field due to the different characteristics in the ground motions. To investigate the effect, the dynamic response and seismic damage of this spatial structures subjected to two different ground motions were numerically studied by nonlinear dynamic response analysis. Firstly, twelve seismic waves with an apparent velocity pulse, including horizontal and vertical seismic waves, were selected to represent the near-fault ground motion characteristics. In contrast, twelve seismic records recorded at the same site from other or same events where the epicenter was far away from the site were employed as the far-fault ground motions. Secondly, the parametric modeling process of Kiewitt single-layer reticulated domes using the finite-element package ANSYS was described carefully. Thirdly, a nonlinear time-history response analysis was carried out for typical domes subjected to different earthquakes, followed by analyzing the dynamic response and seismic damage of this spatial structures under two different ground motions based on the maximum nodal displacements and Park-Ang index as well as dissipated energy. The results showed that this spatial structures in the near field of a rupturing fault exhibit a larger dynamic response and seismic damage than those obtained from far-fault ground motions. In addition, the results also showed that the frequency overlap between structures and ground motions has a significant influence on the dynamic response of the single-layer reticulated shells, the duration of the ground motions has little effects.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.58-65
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• 2003

The seismic response analysis of a freestanding spent fuel storage cask model are performed for an artificial time history acceleration generated by the basis on the US NRC RG1.60 response acceleration spectrum. This paper focuses on the structural stability by seismic loads to check the overturing possibility of storage cask and the slipping displacement on bed. Parametric analyses of a simplified cask model are performed to take into account the variations in seismic load magnitude and cask/bed interface friction. The analyses results show that the storage cask has a large marginal integrity in the response acceleration and slipping distance for both design seismic and beyond design seismic loads.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1159-1164
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• 2005

Seismic analysis methods in use on ground structure are equivalentstatic analysis, response-displacement method and dynamic analysis etc. Equivalentstatic analysis does not considerdynamic effect, and dynamic analysis process is very complex. then 'Urbanrail transit earthquake-resistance design standard (2005.06)' is persuading that analyze by response displacement method that consider enough dynamic effect of ground structure statically. But, It is very complex and difficult to apply response-displacement method in the field. So, modified equivalentstatic analysis or pseudo static analysis that is easy to apply in the field and have rationality of design is practically used. In this study, I try to prescribe the applicable scale of structure and static analysis that have calculative effectiveness about response-displacement method by comparing and analyzing the result of each analysis method according to the scale of urban rail transit' box type concrete structure and by performing seismic analysis that apply modified equivalentstatic analysis, pseudo static analysis and response-displacement method changing the kind of ground, depth of bedrock, size of structure.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.79-89
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• 2000

In this paper, the seismic analysis and the modeling techniques have been introduced for aseismic performances assessment, when seismic isolation bearings are applied on a real bridge. Nonlinear time-history analysis is carried out using finite element analysis program. In this study, EI Centro earthquake(1940, N00W), Mexico earthquake(1985, N90W), and earthquake simulation from modified SIMQKE are used as earthquake ground excitations. The seismic response of seismically isolated bridge is compared with that of a bridge using conventional Pot Bearings, after obtaining the displacements of the deck, the deformations of the piers, shear forces and moments of the bottoms of the piers. The analytical analysis results show that seismic isolation bearing, especially seismic isolation bearings with sliding mechanism, could reduce earthquake forces.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.608-612
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• 2003

In the seismic response analysis, the artificial earthquake time history is generated to do the exact seismic analysis for the complex structural system like as containment building. In the present study the several simulated earthquakes are generated by use of SIMQKE program and the time history dynamic analysis of containment building is performed. Also, the seismic responses are statistically analyzed. The seismic response uncertainty arisen from the simulation of earthquakes is one of major uncertainties and the statistical description is needed to account for the random nature of earthquake.

• Earthquakes and Structures
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• v.20 no.4
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• pp.405-415
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• 2021

Following the dynamic property analysis and elaboration, linear response spectrum analysis (RSA) and response history analysis (RHA) were conducted on a representative hyperbolic cooling towers (HCT) in present study. The seismic responses in tower shell were illustrated in detail, including the internal force amplitude, modal contribution, influence from damping ratio, comparison of results got from RSA and RHA and especially the latitude distributions of internal forces. The results show that the eigenmodes could be classified in a new method into four types according to their mode shapes and only the lateral bending modes and vertical stretching modes are meaningful for horizontal and vertical earthquake correspondingly. The bending modes and seismic deformation display the same feature which is global lateral bending accompanied by minute circular flow displacement of section. This feature also decides the latitude distributions of internal forces as sine or cosine. Moreover, the following method is also proposed for approximate estimation of internal force amplitudes without time-consuming response history analysis: getting the response spectrums of the selected ground accelerations and then comparing values of response spectrums at the natural period of first lateral bending mode because it is always prime dominant for horizontal seismic responses.

• Geomechanics and Engineering
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• v.6 no.6
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• pp.517-530
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• 2014

Seismic ground response analysis is one of the most important issues in geotechnical earthquake engineering. Conventional seismic site response and free field analysis of layered soils does not consider the effect of surcharge mass which may be present on the top layer. Surcharge mass may develop extra inertial force to the soil and, hence, significantly affect on the results of seismic ground response analysis. Methods of analysis of ground response may also be categorized into time domain and frequency domain concepts. Simplicity in developing analytical relations and accuracy in considering soil dynamic properties dependency to loading frequency are benefits of frequency domain analysis. In this part of the paper, seismic ground response is analyzed using transfer function method for soil layers considering surcharge mass on the top layer. Equation of motion, wave equation, is solved using amended boundary conditions which effectively take the impact of surcharge mass into account. A computer program is developed by MATLAB software based on the solution method developed for wave equation. Layered soils subjected to earthquake loading were numerically studied and solved especially by the computer program developed in this research. Results obtained were compared with those given by DEEP SOIL computer program. Such comparison showed the accuracy of the program developed in this study. Also in this part, the effects of geometrical and mechanical properties of soil layers and especially the impact of surcharge mass on transfer function are investigated using the current approach and the program developed. The efficiency and accuracy of the method developed here is shown through some worked examples and through comparison of the results obtained here with those given by other approaches. Discussions on the results obtained are presented throughout in this part.

• Earthquakes and Structures
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• v.4 no.4
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• pp.341-363
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• 2013

Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.380-387
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• 2005

Little has been understood about the seismic behavior of curved bridges due to the different structural characteristics compared to straight bridges. In this study, a simple numerical model, widely used for seismic analysis, is modified for a more realistic estimation of the seismic behavior. The seismic response of curved bridges obtained with the modified simple numerical model was compared with the result using a more sophisticated model to verify the feasibility. Seismic analyses were performed on three-span continuous curved bridges, which is a structural system widely used in highway structures. Numerical model of the three-span continuous curved bridges were subjected to seismic loads in diverse directions. From the result of the analysis. it was found that the direction of the seismic load have significant effect of the seismic behavior of curved bridges when the central angle exceeds 90 degrees.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.5
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• pp.25-33
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• 2011

In the nonlinear response history analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structural systems. As the properties of the ground motion, using time history analysis, are interrelated with many factors such as the fault mechanism, the seismic wave propagation from source to site, and the amplification characteristics of the soil, it is difficult to properly select the input ground motions for seismic response analysis. In this paper, the most unfavourable real seismic design ground motions were selected as input motions. The artificial earthquake waves were generated according to these earthquake events. The artificial waves have identical phase angles to the recorded earthquake waves, and their overall response spectra are compatible with the seismic design spectrum with 5% of critical viscous damping. It is concluded that the artificial earthquake waves simulated in this paper are applicable as input ground motions for a seismic response analysis of building structures.