PURPOSES : Construction standards have resolved overlaps and conflicts between different standards and fields through the introduction of a code system. However, the sub-technical standards were established based on the construction standards at the time of their creation and have not been revised. This has resulted in poor integration and conflicts with revised construction standards, reducing their practical applicability in the construction field. Consequently, to enhance the practical applicability of sub-technical standards and ensure their integration with construction standards, this study aimed to devise technical guidelines for sub-technical standards. METHODS : A brainstorming session was conducted with field experts to evaluate the applicability and necessity of the currently distributed sub-technical standards in the field. Each sub-technical standard was reviewed to determine whether it should be retained or abolished. On the basis of the review results, this study developed a set of draft technical guidelines (Korean Design Standard Guideline (KDSG)/Korean Construction Specification Guideline (KCSG)) for the sub-technical standards that required retention. RESULTS : A comprehensive survey of sub-technical standards identified a total of 154 standards. Of these, 109 were deemed necessary to retain, whereas 45 were considered unnecessary to retain. Among the sub-technical standards requiring retention, 20 were selected for the development of technical guidelines based on their relevance and applicability to the construction standards. A draft of these technical guidelines was subsequently prepared. CONCLUSIONS : A plan was devised to assign technical guideline codes to 20 subordinate technical standards that were deemed consistent with the road construction standards (KDS/KCS 44 00 00). This approach can provide a foundation for reorganizing the system of road construction standards and subordinate technical standards, thereby enhancing their practical usability in the construction field.

The site coefficients in the common requirements for seismic design codes, which were promulgated in 2017, were reevaluated and the standard design spectrum for soil sites were newly proposed in order to ensure the consistency of the standard design spectra for rock and soil sites specified in the common requirements. Using the 55 ground motions from domestic and overseas intraplate earthquakes, which were used to derive the standard design spectrum for rock sites, as rock outcropping motions, site response analyses of Korean soil were performed and its ground-motion-amplification was characterized. Then, the site coefficients for soil sites were reevaluated. Compared with the existing site coefficients, the newly proposed short-period site coefficient Fa increased and the long-period site coefficient Fv decreased overall. A new standard design spectrum for soil sites was proposed using the reevaluated site coefficients. When compared with the existing design spectrum, it could be seen that the proposed site coefficients and the standard design spectrum for soil sites were reasonably derived. They reflected the short-period characteristics of earthquake and soil in Korea.

On November 15, 2017, Pohang earthquake occurred. Its local magnitude was announced to be ML=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 the Korean 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.

In this study, we develop and propose damping correction factors for the Korean standard design spectra. The newly proposed Korean standard design spectra has been given only for 5% damping ratio. But in practice, engineers need design spectra for damping values other than 5%. To obtain design spectra for various damping values from the standard spectra, damping correction factors are derived. These factors modify the shape of design spectra in accordance with the damping ratio. Response spectra for various damping values are calculated from the earthquake records that had been used to calculate standard design spectra. They consist of 55 records from 18 earthquakes occurred in overseas intraplate regions and Korea. The regressed spectra for the damping values ranging from 0.5% to 50% are compared with standard spectra at three regions acceleration, velocity and displacement sensitive regions. The regression analysis of these data rendered formula for damping correction factors. Finally, a single formula for damping correction factors is recommended that is valid for both horizontal and vertical design spectra and that is applicable to the entire range of periods. One thing to note that recommended damping correction factors is valid for the design spectrum of the rock grounds because the design spectra was developed based on the earthquake records of the rock ground.

On September 12, 2016, Gyeongju earthquake occurred. Its local magnitude was announced to be ML=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.

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.

The 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. The horizontal spectrum is 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. The developed design spectrum is valid for the estimation both spectral acceleration and displacement.