• Nuclear Engineering and Technology
• /
• v.48 no.3
• /
• pp.831-839
• /
• 2016

Seismic qualification by test is widely used as a way to show the integrity and functionality of equipment that is related to the overall safety of nuclear power plants. Another means of seismic qualification is by direct integration analysis. Both approaches require a series of time histories as an input. However, in most cases, the possibility of using real earthquake data is limited. Thus, artificial time histories are widely used instead. In many cases, however, response spectra are given. Thus, most of the artificial time histories are generated from the given response spectra. Obtaining the response spectrum from a given time history is straightforward. However, the procedure for generating artificial time histories from a given response spectrum is difficult and complex to understand. Thus, this paper presents a simple time-domain method for generating a time history from a given response spectrum; the method was shown to satisfy conditions derived from nuclear regulatory guidance.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.45-58
• /
• 2017

As many seismic codes for various facilities are changed into a performance based design code, demand for a reliable nonlinear response-history analysis (RHA) arises. However, the equivalent linear analysis has been used as a standard approach since 1970 in the field of site response analysis. So, the reliability of nonlinear RHA should be provided to be adopted in replace of equivalent linear analysis. In this paper, the reliability of nonlinear RHA is reviewed for a layered soil layer using Loma Prieta earthquake records in 1989. For this purpose, the appropriate way for selecting nonlinear soil models and the effect of base boundary condition for 3D analysis are evaluated. As a result, there is no significant differences between equivalent linear and nonlinear RHA. In case of 3D analysis, absorbing boundary condition should be applied at base to prevent rocking motion of the whole model.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.1
• /
• pp.1-11
• /
• 2016

The domestic and foreign seismic design codes have specified that time history covers design response spectrum when the response spectrum, which calculated from the time history, is smaller than the design response spectrum at five points or less. In order to verify the design codes, time history analysis for a pier was performed by using five artificial time histories conforming design code with various characteristics and its member forces were evaluated according to them. It was confirmed from analysis results that, regardless of the conformity to design code requirement, seismic design using the artificial time histories could not guarantee earthquake resistant design if the response spectrum from them is lower than design response spectrum at the similar period to the natural frequency of structure. Thus, the time history generating method to make its acceleration response spectrum to be greater than design response spectrum at all period was proposed by two modification function in this study. It was also verified whether time histories from the proposed method satisfy the seismic design codes or not.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.6 no.3 s.22
• /
• pp.29-35
• /
• 2006

Fiber element method in earthquake response analysis of bridges is used to represents a realistic flexural deformation according to nonlinear behavior of beam-column section. Nonlinear pseudo-static analysis of two column bent using fiber element is accomplished and failure mechanism of the plastic hinge region is studied. Load-displacement curve obtained by nonlinear pseudo-static analysis can be applicable to earthquake response analysis by capacity spectrum method. The nonlinear time history analysis of a full bridge model using fiber element experienced by the ground motion corresponding to the target response spectrum is accomplished. The result of time history analysis is similar to that of capacity spectrum method.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.652-659
• /
• 2005

Even in moderate to low seismic regions like Korean peninsular where wind loading usually governs the structural design of a tall building, the probable structural impact of the design basis earthquake or the maximum credible earthquake on the selected structural system should be considered at least in finalizing the design. In this study, by using response spectrum analysis and linear time history analysis method, seismic performance evaluation was conducted for wind-designed concentrically braced steel highrise buildings. Both spectrum-compatible artificial accelerograms and recorded accelerograms were used as input ground motions for the time history analysis. The analysis results showed that wind-designed concentrically braced steel highrise buildings possess significantly increased elastic seismic capacity due to the system overstrength resulting from the wind-serviceability criterion and the width-to-thickness ratio limits on steel members. Time history analysis results generally tended to underestimate the seismic response as compared to those of response spectrum analysis.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.24 no.6
• /
• pp.267-275
• /
• 2020

In the event of an earthquake, non-structural components require seismic performance to ensure evacuation routes and to protect lives from falling non-structural components. Accordingly, the seismic design code proposes horizontal force for the design and evaluation of non-structural components. Ground motion observed on each floor is affected by a building's eigen vibration mode. Therefore, the earthquake damage of non-structural components is determined by the characteristics of the non-structural component system and the vibration characteristics of the building. Floor response spectra in the seismic design code are estimated through time history analysis using seismic waves. However, it is difficult to use floor response spectra as a design criterion because of user-specific uncertainties of time history analysis. In addition, considering the response characteristics of high-rise buildings to long-period ground motions, the safety factor of the proposed horizontal force may be low. Therefore, this study carried out the horizontal force review proposed in the seismic design code through dynamic analysis and evaluated the floor response of seismic waves considering buildings and predominant periods of seismic waves.

• Tuberculosis and Respiratory Diseases
• /
• v.82 no.1
• /
• pp.35-41
• /
• 2019

Background: Pulmonary tuberculosis can result in anatomical sequelae, and cause airflow limitation. However, there are no treatment guidelines for patients with a tuberculosis-destroyed lung. Recently, indacaterol effectiveness in chronic obstructive pulmonary disease (COPD) patients with Tuberculosis history (INFINITY) study revealed indacaterol provided bronchodilation and symptom improvement in COPD patients with a tuberculosis-destroyed lung. Methods: We conducted a post-hoc subgroup analysis of the randomized controlled trial, the INFINITY study, to determine factors associated with indacaterol response in a tuberculosis-destroyed lung with airflow limitation. Data from 68 patients treated with inhaled indacaterol, were extracted and analyzed. Factors associated with the response of forced expiratory volume in one second ($FEV_1$) to indacaterol treatment, were determined using linear regression analysis. Results: Of 62 patients included, 68% were male, and 52% had history of cigarette smoking. Patients revealed mean $FEV_1$ of 50.5% of predicted value with mean improvement of 81.3 mL in $FEV_1$ after indacaterol treatment for 8 weeks. Linear regression analysis revealed factors associated with response of $FEV_1$ to indacaterol included a short duration of smoking history, and high short-acting bronchodilator response. When patients with history of smoking were excluded, factors associated with response of $FEV_1$ to indacaterol included high short-acting bronchodilator response, and poor health-related quality of life score as measured by St. George's Respiratory Questionnaire for COPD. Conclusion: In a tuberculosis-destroyed lung with airflow limitation, short-acting bronchodilator response and smoking history can play a critical role in predicting outcomes of indacaterol treatment.

• Structural Engineering and Mechanics
• /
• v.55 no.6
• /
• pp.1203-1221
• /
• 2015

By taking a cable-stayed-suspension hybrid bridge with main span of 1400 m as example, seismic response of the bridge under the horizontal and vertical seismic excitations is investigated numerically by response spectrum analysis and time history analysis, its seismic performance is discussed and compared to the cable-stayed bridge and suspension bridge with the same main span, and considering the aspect of seismic performance, the feasibility of using cable-stayed-suspension hybrid bridge in super long-span bridges is discussed. Under the horizontal seismic action, the effects of structural design parameters including the cable sag to span ratio, the suspension to span ratio, the side span length, the subsidiary piers in side spans, the girder supporting system and the deck form etc on the seismic performance of the bridge are investigated by response spectrum analysis, and the favorable values of these design parameters are proposed.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2007.04a
• /
• pp.639-644
• /
• 2007

The accurate peak response estimation of a seismically excited structure with frictional damping system(FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated that by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In the case that on earthquake load is defined with probabilistic characteristics, the corresponding response of the structure with FDS has probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake loads generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Finally, coefficients of the proposed PDF is obtained by regression analysis of the statistical distribution of the time history responses. Finally, the correlation between PDFs and statistical response distribution is presented.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.631-638
• /
• 2006

This paper considers the nonlinear direct spectrum method to estimate seismic performance of mixed building structures without iterative computations, given dynamic property $T_1$ from stiffness skeleton curve and nonlinear pseudo acceleration $A_{1y}$ and/or ductility ratio $\mu$ from response spectrum. Nonlinear response history analysis has been performed and analysed with various earthquakes for evaluation of correctness and confidence of nonlinear direct spectrum method.