• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.4
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• pp.1-9
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• 1997

This paper examined various aspects of a linear and a nonlinear response spectrum method in seismic response analysis of multi-story building structures. The response spectrum method that has been widely used in the analysis of linear structures was proposed different mode superposition method by several ivestigators, and the differences between combinations with an elastic modal analysis reviwed closely. It seems, however, that this method is not used to nonlinear seismic analysis. It is the purpose of this paper to propose an alternative method by means of which a nonlinear MDOF structure with long period may be analysed by an extention of response spectrum method. For nonlinear seismic analysis of high-rise building structures using technique proposed in this study, it is intended to serve primarily as a tool in preliminary designs instead of time history analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.177-184
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• 2021

In recent years, large-scale earthquake activity has occurred in Korea, and thus public interest in earthquakes is increasing. Accordingly, the importance of seismic performance management of structures is emerging. In particular, the collapse of a bridge, one of main road facilities, directly leads to many casualties. Therefore, engineers need to evaluate the seismic fragility of the bridge and prepare for the earthquake event. The service life of these bridges has been over 30 years, which requires a study on the aging effect on bridges. In this study, seismic analysis of the target RC slab bridge was performed considering the aging effects of each component of the bridge. Components of the bridge included pier and bearing, which dominate the seismic response of the bridge. The seismic performance of the bridge was evaluated using nonlinear static and dynamic analyses. In addition, the limit state and dynamic response of each component were used to evaluate the seismic fragility according to the aging of each component.

• Nuclear Engineering and Technology
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• v.30 no.3
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• pp.212-221
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• 1998

In the present study, a method for the dynamic analysis of a reactor core is developed. Peak responses for the motions induced from earthquake are obtained for a core model. The dynamic responses such as fuel assembly shear force, bending moment, axial force and displacement, and spacer grid impact loads are investigated. Prediction of fuel assembly stress during an earthquake requires development of a fuel assembly stress analysis model capable of interfacing with the models and results discussed in the dynamic analysis of a reactor core. This analysis uses beam characteristics which describe the overall fuel assembly response. The stress analysis method and its application for the case of an increased seismic level are also presented.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.349-352
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• 2006

According to current bridge design code cable supported bridges are designed generally against 1000-year-return-period earthquake. Considering its importance, however, it may be desirable to design against 2400-year-return-period earthquake. But the seismic behavior of cable supported bridges under higher seismicity is not investigated fully. In this study, several cable supported bridges were analyzed under higher seismicity and then the response forces in prime members were compared with those analyzed under current design earthquake.

• Geomechanics and Engineering
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• v.24 no.2
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• pp.193-203
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• 2021

The time-history finite element analysis is usually used to evaluate the seismic response of shallow foundations. However, the literature lacks studies on the influence of the soil constitutive model complexity on the seismic response of shallow foundations. This study, thus, aims to fill this gap by investigating the seismic response of shallow foundation resting on dry silica sand using the linear elastic (LE) model, elastic-perfectly-plastic (EPP) model, and hardening soil with small strain stiffness (HS small) model. These models have been used because it is intended to compare the results of a soil constitutive model that accurately captures the seismic response of the soil-structure interaction problems (which is the HS small model) with simpler models (the LE and EPP models) that are routinely used by practitioners in geotechnical designs. The results showed that the LE model produces a very small seismic settlement value which is approximately equal to zero. The EPP model predicts a seismic settlement higher than that produced using the HS small model for earthquakes with a peak ground acceleration (PGA) lower than 0.25 g for a relative density of 45% and 0.40 g for a relative density of 70%. However, the HS small model predicts a seismic settlement higher than the EPP model beyond the aforementioned PGA values with the difference between both models increases as the PGA rises. The results also showed that the LE and EPP models predict similar trend and magnitude of the acceleration-time relationship directly below the foundation, which was different than that predicted using the HS small model. The results reported in this paper provide a useful benchmark for future numerical studies on the response of shallow foundations subjected to seismic shake.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.25-32
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• 2002

In the seismic designing of bridges, the pile foundation of bridge piers generally have been modeled to have a fixed end for its convenience and conservative designing. The fixed-end assumption, however, produces very conservative results in terms of the pier forces. Therefore, many other design methods are evolved to consider the flexibility of the pile foundation. In this study, the response spectrum analysis was performed for a bridge pier having a pile foundation. The shear force, moment, and displacement, which occurred at the pier column under an earthquake loading, were compared to analyze the effects of the modeling method, soil condition and the input earthquake response spectrum. In most cases, the fixed-end model gives larger design forces than flexible foundation models. However, when a long period earthquake is applied to the bridge pier on a soft clay foundation, it is found that the flexible foundation models give larger design forces than the fixed-end model. In the end, the reliability of several flexible foundation models was verified by comparing their results with those of a numerical analysis that considers the soil-structure interaction phenomenon in a rigorous manner.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.33-42
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• 2005

Even in moderate to low seismic regions like Korean peninsular where wind loading usually governs the structural design of a tall builidng, the probable structural impact of the 500-year design basis earthquake (DBE) or the 2400-year maximum credible earthquake (MCE) on the selected structural system should be considered at least in finalizing the design. In this study, seismic performance evaluation was conducted for concentrically braced steel highrise buildings that were only designed for wind by following the assumed domestic design practice. It was found that wind-designed concentrically braced steel highrise buildings possess significantly increased elastic seimsic capacity due to the system overstrength resulting from the wind-serviceability criterion and the width-to-thickness ratio limits on steel members. The strength demand-to-strength capacity study based on the response spectrum analysis revealed that, due to the system overstrength factors mentioned above, wind-designed concentrically braced steel highrise buildings having a slenderness ratio of larger than six can withstand elastically even the maximum credible earthquake at the performance level of immediate occupancy.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.6
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• pp.245-255
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• 2013

According to natural frequency of soil, characteristics of earthquake responses of an isolated containment building in nuclear power plants are examined. For this, earthquake response analysis of seismically isolated containment buildings in nuclear power plants is carried out by strictly considering soil-structure interactions. The structure and near-field soil are modeled by the finite element method while far-field soil by consistent transmitting boundary. The equation of motion of a soil-structure interaction system under incident seismic wave is derived. The derived equations of motion are solved to carry out earthquake analysis of a seismically isolated soil-structure system. Generally, the results of this analysis show that seismic isolation significantly reduces the responses of the soil-structure system. However, if the natural frequency of the soil is similar to that of the soil-structure system, the responses of the containment buildings in nuclear power plants rather increases due to interactions in the system.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2396-2406
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• 2021

The Pacific Earthquake Engineering Research (PEER) Center has been developing a performance-based earthquake engineering (PBEE) methodology, which is based on explicit determination of performance, e.g., monetary losses, in a probabilistic manner where uncertainties in earthquake ground motion, structural response, damage estimation, and losses are explicitly considered. To carry out the PEER PBEE procedure for a component of the nuclear power plant (NPP) such as the cable tray system, hazard curve and spectra were defined for two hazard levels of the ground motions, namely, operation basis earthquake, and safe shutdown earthquake. Accordingly, two sets of spectral compatible ground motions were selected for dynamic analysis of the cable tray system. In general, the PBEE analysis of the cable tray in NPP was introduced where the resulting floor motions from the time history analysis (THA) of the NPP structure should be used as the input motion to the cable tray. However, for simplicity, a finite element model of the cable tray was developed for THA under the effect of the selected ground motions. Based on the structural analysis results, fragility curves were generated in terms of specific engineering demand parameters. Loss analysis was performed considering monetary losses corresponding to the predefined damage states. Then, overall losses were evaluated for different damage groups using the PEER PBEE methodology.

• Computational Structural Engineering
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• v.22 no.3
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• pp.35-40
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• 2009