• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.445-452
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• 2005

The seismic characteristics with Friction Pendulum System have been studied using a shaking table system. In this study, we made two kind of floor system (Type I, Type II) and several seismic tests with and without isolation system were conducted to evaluate floor isolation effectiveness of Friction Pendulum System. Both type have showed large reduction effectiveness in acceleration, response spectra but Type II have showed lower acceleration and lower first mode in response spectra, compared to type I. On the basis of test results and consideration of application, it is found that type II is more suitable for floor model of main control room of Nuclear Power Plant.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.107-114
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• 1997

A dynamic fluid-structure-soil interaction analysis method is developed to investigate the effects of rocking motion on the seismic response of the 3-D flexible rectangular liquid storage tanks founded on the deformable ground. The governing equation of 3-D rectangular tanks subjected to the translational and rocking motions is obtained by Rayleigh-Ritz method. The dynamic stiffness matrix of the rigid surface foundation resting on the surface of a stratum are calculated by hyperelement method. The seismic responses of a 3-D flexible tank model founded on the deformable ground is calculated by combining the governing equation of the structural motion with the dynamic stiffness matrix of the rigid surface foundation.

• Earthquakes and Structures
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• v.11 no.1
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• pp.179-193
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• 2016

The effectiveness of 100/30, 100/40 and SRSS directional combination rules on the response of asymmetric setback buildings is examined. Because of the irregularity in setback buildings, the maximum seismic response would be correlative with the direction of earthquake. To verify the directional combination rules of mode superposition methods, the time history analyses of setback buildings to real earthquake records are carried out. Example analyses have been used to compare the validty and accuracy of SRSS and percentage methods for frame and dual frame-wall systems.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.128-135
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• 1998

In this study, the unseating failure of the bridge spans under seismic excitations is examined by investigation the nonlinear response behaviors of the bridge system with reinforced concrete piers. To reduce the computational effort and to consider the effect of the foundation motions, a simplified 3 degree-of-freedom model is proposed, which retains the dynamic characteristics of the original bridge motions in concern. To imply the nonlinear behaviors of the RC piers to the system. a hysteresis model is utilized from the calculated force-deformation curve for the piers. The statistical characteristics of the maximum response displacements are obtained from the simulation results of 1000 time history analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.57-60
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• 1999

Amplification factor spectrum using the observed strong ground motions database in the Korean Peninsula has been obtained and compared with Standard Rpectrum which wa suggested by United States Nuclear Regulatory Committee. The observed ground motions from the Yongwol and the Kyoungju Earthquakes respectively which are supposed to represent domestic seismotectonic characteristics such as seismic source attenuation of the propagation meium and site specific effect are used for the analysis of amplification factor spectrum,. The database are slightly different from the those of the second study. Amplification factors have been calculated by comparing the observed peak ground motions with results from responses to the observed horizontal na vertical ground motions. The comparison have shown that the amplification factors resultant from this study exceeds those of Standard Response Spectrum The results suggest that the characteristics of seismic strong ground motion which are supposed to represent the domestic seismotectonic characteristics differs from those of Standard Response Spectrum especially at higher frequencies. The results from the 2nd study are similar to those of 1st analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.85-92
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• 2003

Hysteretic behaviors of a seismic isolator are identified by using the regularized output error estimator (OEE) based on the secant stiffness model. A proper regularity condition of tangent stiffness for the current OEE is proposed considering the regularity condition of Duhem hysteretic operator. The proposed regularity condition is defined by 12-norm of the tangent stiffness with respect to time. The secant stiffness model for the OEE is obtained by approximating the tangent stiffness under the proposed regularity condition by the secant stiffness at each time step. A least square method is employed to minimize the difference between the calculated response and measured response for the OEE. The regularity condition of the secant stiffness is utilized to alleviate ill-posedness of the OEE and to yield numerically stable solutions through the regularization technique. An optimal regularization factor determined by geometric mean scheme (GMS) is used to yield appropriate regularization effects on the OEE.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.201-208
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• 2006

This study lotuses on the seismic behavior of 3-, 9-, and 20-story steel moment resisting frame (MRF) structures designed in accordance with the 2000 International Building Code using different Response Modification factors (R factors) 8, 9, 10, 11, and 12. For a detailed case study, 30 different structures were evaluated for twenty ground motions representing the hazard level which is equal to a 2% probability exceeding in 50 years (2% in 50 years). The results showed that the current R factors provide conservative designs for the 3- and 9-story buildings for the Collapse Prevention performance objective. However, the 20-story buildings designed without using the minimum requirement of spectral acceleration CS prescribed in the IBC 2000 did not satisfy the seismic performance for Collapse Prevention performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.409-416
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• 2006

The seismic characteristics with 3-Dimensional Floor Isolation System have been studied using a shaking table system. In this study, we made two kind of floor system (Type I, Type II) and several seismic tests with and without isolation system were conducted to evaluate 3-Dimensional Floor Isolation Effectiveness. Both type have showed large reduction effectiveness in acceleration, response spectra but Type II have showed lower acceleration and lower first mode in response spectra, compared to type I. On the basis of test results and consideration of application, it is found that type II is more suitable for floor model of main control room of Nuclear Power Plant.

• Steel and Composite Structures
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• v.37 no.4
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• pp.447-462
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• 2020

In this paper, a simplified seismic design method for low-rise dual frame-steel plate shear wall (SPSW) structures is proposed in the framework of performance-based seismic design. The dynamic response of a low-rise structure is mainly dominated by the first-mode and the structural system can be simplified to an equivalent single degree-of-freedom (SDOF) oscillator. The dual frame-SPSW structure was decomposed into a frame system and a SPSW system and they were simplified to an equivalent F-SDOF (SDOF for frame) oscillator and an equivalent S-SDOF (SDOF for SPSW) oscillator, respectively. The analytical models of F-SDOF and S-SDOF oscillators were constructed based on the OpenSees platform. The equivalent SDOF oscillator (D-SDOF, dual SDOF) for the frame-SPSW system was developed by combining the F-SDOF and S-SDOF oscillators in parallel. By employing the lateral force resistance coefficients and seismic demands of D-SDOF oscillator, the design approach of SPSW systems was developed. A 7-story frame-SPSW system was adopted to verify the feasibility and demonstrate the design process of the simplified method. The results also show the seismic demands derived by the equivalent dual SDOF oscillator have a good consistence with that by the frame-SPSW structure.

• Earthquakes and Structures
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• v.15 no.4
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• pp.431-441
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• 2018

This study provides fragility-based assessment of seismic performance of reinforced concrete bridges. Seismic fragility curves were created using nonlinear analysis (NA) and artificial neural networks (ANNs). Nonlinear response history analyses were performed, in order to calculate the seismic performances of the bridges. To this end, 306 bridge-earthquake cases were considered. A multi-layered perceptron (MLP) neural network was implemented to predict the seismic performances of the selected bridges. The MLP neural networks considered herein consist of an input layer with four input vectors; two hidden layers and an output vector. In order to train ANNs, 70% of the numerical results were selected, and the remained 30% were employed for testing the reliability and validation of ANNs. Several structures of MLP neural networks were examined in order to obtain suitable neural networks. After achieving the most proper structure of neural network, it was used for generating new data. A total number of 600 new bridge-earthquake cases were generated based on neural simulation. Finally, probabilistic seismic safety analyses were conducted. Herein, fragility curves were developed using numerical results, neural predictions and the combination of numerical and neural data. Results of this study revealed that ANNs are suitable tools for predicting seismic performances of RC bridges. It was also shown that yield stresses of the reinforcements is one of the important sources of uncertainty in fragility analysis of RC bridges.