• Journal of the Earthquake Engineering Society of Korea
• /
• v.20 no.6
• /
• pp.413-424
• /
• 2016

The vertical design spectrum for Korea, which is known to belong to an intra-plate region, is developed from the ground motion records of the earthquakes occurred in Korea and overseas intra-plate regions. From the statistical analysis of the vertical response spectra, a mean plus one standard deviation spectrum in lognormal distribution is obtained. Regression analysis is performed on this curve to determine the shape of spectrum including transition periods. The developed design spectrum is valid for the estimation both spectral acceleration and displacement. The ratio of vertical to horizontal response spectrum for each record is calculated. Statistical analysis of the ratios rendered the vertical to horizontal ratio (V/H ratio). Subsequently the ratio between the peak vertical ground acceleration to the horizontal one is obtained.

• Geophysics and Geophysical Exploration
• /
• v.13 no.3
• /
• pp.227-234
• /
• 2010

The vertical response spectra using the observed ground motions from the recent more than 30 macro earthquakes were analysed and then were compared both to the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and to the Korean Standard Design Response Spectrum for general structures and buildings (1997). 176 vertical ground motions, without considering soil types, were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that response spectrum had strong dependency on epicentral distance. The results also showed that the vertical response spectra revealed much higher values for frequency bands above 5~7 Hz than Reg. Guide (1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed much higher values for the frequency bands below 0.2 second (5 Hz) than the Korean Standard Response Spectrum (SD soil condition). These frequency-dependent spectral values could be related to the characteristics of the domestic crustal attenuation and the effect of each site amplification. However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of vertical seismic design response spectrum should be considered more significantly for the frequency bands above 5 Hz.

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.1
• /
• pp.81-87
• /
• 2011

The characteristics of vertical to horizontal ratio of response spectrum from 20 recent earthquakes were analysed. Response spectrum of 260 horizontal and 130 vertical ground motions were normalized by peak ground acceleration at each resonance frequency from 0.1 to 50Hz. It has been identified that the ratio of vertical to horizontal response spectrum has strong dependancy on epicentral distance and resonance frequency. The ratio of vertical to horizontal response spectrum for the 0-50km epicentral distance group are larger than 2/3 values, which is a standard engineering rule-of-thumb V/H=2/3, at resonance frequency above 7-8Hz. All the 3 groups such as 50-100, 100-150- and 150-200km epicentral distance have shown larger values of vertical to horizontal ratio than 2/3 at resonance frequency above 15Hz and also are larger than 2/3 at resonance frequency below 8-10Hz. Even though there are differences in specific resonance frequency values which depend on the epicentral distance group, we should be careful of seismic design of vertical component of the structures winch are located within the range of about 200km distance. form the potentially seismic causative faults.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.21 no.6
• /
• pp.277-286
• /
• 2017

On September 12, 2016, Gyeongju earthquake occurred. Its local magnitude was announced to be $M_L=5.8$ by Korea Meteorological Administration (KMA). Ground motion data recorded at KMA, EMC and KERC stations was obtained from their data bases. From the data, horizontal and vertical response spectra, and V/H ratio were calculated. The horizontal spectrum was defined as geometric mean spectrum, GMRotI50. From the statistical analysis of the geometric mean spectra, a mean plus one standard deviation spectrum in lognormal distribution is obtained. Regression analysis is performed on this curve to determine the shape of spectrum including transition periods. Applying the same procedure, the shape and transition periods of vertical spectrum was obtained. These results were compared with the Korean standard design spectra, which were developed from domestic and overseas intraplate earthquake records. The response spectra of Gyeongju earthquake were found to be almost identical with the newly proposed design spectra. Even the V/H ratios showed good agreement. These results confirmed that the method adopted when developing the standard design spectra were valid and the developed design spectra were reliable.

• Tunnel and Underground Space
• /
• v.19 no.6
• /
• pp.490-497
• /
• 2009

The horizontal and vertical response spectra using the observed ground motion from the recent 5 macro earthquakes were analysed and then were compared to both the seismic design response spectra(Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings(1997). 74 horizontal and 89 vertical observed ground motions, without considering soil types, were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal MPOSD(Mean Plus One Sigma Standard Deviation) response spectra revealed much higher values for the whole frequency bands above 1 Hz than Reg. Guide(1.60). For the vertical response spectra, the results showed slightly higher than just between 7 and 8 Hz frequency band. The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the horizontal MPOSD response spectra revealed much higher values for the whole periods below 2 second(0.5 Hz) than those of SE soil type. The vertical response spectra showed similar to the values of the Korean Standard Response Spectrum of SD soil type. These spectral values dependent on frequency could be related to characteristics of the domestic crustal attenuation and the effect of each site amplification. However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the whole frequency bands above the 1 Hz.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.3
• /
• pp.129-137
• /
• 2018

On November 15, 2017, Pohang earthquake occurred. Its local magnitude was announced to be $M_L=5.4$ by Korea Meteorological Administration (KMA). Ground motion data recorded at KMA stations were obtained from their data bases. From the data, horizontal and vertical response spectra, and V/H ratio were calculated. The horizontal spectra were defined as GMRotI50 spectra. From the statistical analysis of the GMRotI50 spectra, a mean plus one standard deviation spectrum in lognormal distribution is obtained. Regression analysis is performed on this curve to determine the shape of spectrum including transition periods. Applying the same procedure, the shape and transition periods of vertical spectrum were obtained. These results were compared with theKorean standard design spectra, which were developed from domestic and overseas intra-plate earthquake records, and Gyeongju earthquake response spectra. The response spectra of Pohang earthquake were found to be almost identical with the newly proposed design spectra. Even the V/H ratios showed good agreement. These results confirmed that the method adopted when developing the standard design spectra were valid and the developed design spectra were reliable.

• Geophysics and Geophysical Exploration
• /
• v.14 no.4
• /
• pp.274-281
• /
• 2011

We analysed ground motions form Mw 4.3 earthquake around Backryoung Island for the seismic source focal mechanism and horizontal response spectrum. Focal mechanism of the Backryoung Islands area was compared to existing principal stress orientation of the Korean Peninsula and horizontal response spectrum was also compared to those of the US NRC Regulatory Guide (1.60) and the Korean National Building Code. The ground motions of 3 stations, including vertical, radial, and tangential components for each station, were used for grid search method of moment tensor seismic source. The principal stress orientation from this study, ENE-WSW, is consistent fairly well with that of the Korean Peninsula. The horizontal response spectrum using 30 observed ground motions analysed and then were compared to both the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). Response spectrum of 30 horizontal ground motions were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal response spectrum revealed higher values for frequency bands above 3 Hz than Reg. Guide (1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed higher values for the frequency bands below 0.8 second than the Korean Standard Response Spectrum (SD soil condition). However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the higher frequency bands.

• 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.

• Journal of the Korean earth science society
• /
• v.28 no.7
• /
• pp.871-877
• /
• 2007

The response spectrum was studied using the observed pound motion from the Odaesan Earthquake (2007/01/20), and then the results were compared to the seismic design response spectra (Reg Guide 1.60) applied to the domestic nuclear power plants. For the response spectrum analysis, 21 horizontal and 8 vertical observed Pound motions were used for normalization and statistical analysis. The results showed that the MPOSD (Mean Plus One Sigma Standard Deviation) response spectra above 10 Hz revealed higher values than the design response spectra and those below 10 Hz revealed much lower values fur both horizontal and vertical response spectra. These results suggest that the response spectra (Reg. Guide 1.60), used as seismic design code for nuclear facilities in Korea, especially above about 10 Hz, should be reexamined fur apllication to the nuclear power plants structures operated in the Korean Peninsula.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.3
• /
• pp.21-27
• /
• 2016

The static and dynamic structural integrity qualification was performed through the seismic analysis of a small-size Savonius-type vertical wind turbine at dead weight plus wind load and seismic loads. The ANSYS finite element program was used to develop the FEM model of the wind turbine and to accomplish static, modal, and dynamic frequency response analyses. The stress of the wind turbine structure for each wind load and dead weight was calculated and combined by taking the square root of the sum of the squares (SRSS) to obtain static stresses. Seismic response spectrum analysis was also carried out in the horizontal (X and Y) and vertical (Z) directions to determine the response stress distribution for the required response spectrum (RRS) at safe-shutdown earthquake with a 5% damping (SSE-5%) condition. The stress resulting from the seismic analysis in each of the three directions was combined with the SRSS to yield dynamic stresses. These static and dynamic stresses were summed by using the same SRSS. Finally, this total stress was compared with the allowable stress design, which was calculated based on the requirements of the KBC 2009, KS C IEC 61400-1, and KS C IEC 61400-2 codes.