• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.4
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• pp.195-205
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• 2015

Various non-seismic tie details are frequently used for one- and two-story small buildings because the seismic demand on their deformation capacities is not relatively significant. To evaluate the effects of the non-seismic tie details on the seismic performance of reinforced concrete columns, six square columns with a cross section of $400{\times}400mm$ and six rectangular columns with a cross section of $250{\times}640mm$ were tested. The anchorage details at both ends and spacing of tie hoops, along with the cross-sectional shape and the magnitude of axial load, were considered as the primary test parameters. Test results showed that square columns had higher stiffness and lower lateral deformation rather than rectangular columns. Both lap spliced tie and U-shaped tie provided comparable or improved seismic performance to $90^{\circ}$ hook tie in terms of maximum strength, ductility, and energy dissipation. The predicted curves with modeling parameters in ASCE41-13 were conservative for test results of lap spliced tie and U-shaped tie specimens since plastic behavior after flexural yielding could not be considered. For economical design, ASCE41-13 should be revised with various test results of tie details.

• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.1-13
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• 2022

For surveying shallow gas reservoirs in the Pohang basin, we proposed a seismic exploration method applicable to the transition zone in which land and marine areas are connected. We designed the seismic acquisition geometry considering both environments. We installed land nodal receivers on the ground and employed vibroseis and airgun sources in both land and marine areas. For seismic exploration in the transition zone, specific acquisition and processing techniques are required to ensure precise matching of reflectors at the boundary between the onshore and offshore regions. To enhance the continuity of reflection events on the seismic section, we performed amplitude and phase corrections with respect to the source types and applied a static correction. Following these processing steps, we obtained a seismic section showing connected reflectors around the boundary in the transition zone. We anticipate that our proposed seismic exploration method can also be used for fault detection in the transition zone.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.210-215
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• 2003

Seismic capacity of reinforced concrete bearing wall subjected to high axial loading and moment can be attained by improving the deformability of compression zone or by reducing the neutral axis depth. For this two existing options for ductility enhancement were reviewed and improved to conveniently apply to the seismic improvement of compression zone of the wall: (1) end confinement of concrete due to transverse steel and (2) boundary element.

• Geophysics and Geophysical Exploration
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• v.26 no.3
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• pp.138-149
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• 2023

In geoscience and engineering the geological characteristics of sediment strata is crucial and possible if reliable borehole logging and seismic data are available. To investigate the characteristics of the shallow strata in the Korea Strait, laboratory sonic logs were obtained from deep borehole data and seismic section. In this study, we integrated and analyzed the sonic log data obtained from the drilling core (down to a depth of 200 m below the seabed) and multichannel seismic section. The correlation value was increased from 15% to 45% through time-depth conversion. An initial model of P-wave impedance was set, and the results were compared by performing model-based, band-limited, and sparse-spike inversions. The derived P-impedance distributions exhibited differences between sediment-dominant and unconsolidated layers. The P-impedance inversion process can be used as a framework for an integrated analysis of additional core logs and seismic data in the future. Furthermore, the derived P-impedance can be used to detect shallow gas-saturated regions or faults in the shallow sediment. As domestic deep drilling is being performed continuously for identifying the characteristics of carbon dioxide storage candidates and evaluating resources, the applicability of the integrated inversion will increase in the future.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.31-40
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• 2017

In this study, a simple method to evaluate the seismic vulnerability of river levees was examined considering the structural characteristic of river levee, that is long, and the functional characteristic of river levee that performs temporary function against flood but is a permanent structure in the ordinary way. Considering the fact that one of the main failure modes of the levee during the earthquake are the settlement due to the strength reduction of the ground caused by the increase of the excess pore pressure in the levee body and foundation and the settlement due to liquefaction, the 2-dimensional section of the levee was regarded as the 1-dimensional section and the liquefaction potential index (LPI) for the regarded section was estimated. The estimated LPI was correlated with the seismic vulnerability of river levees. The relationship between the displacement of the levee crest caused by the earthquake and the seismic vulnerability of the levees was obtained from the results of previous researches and the correlation between the displacements of the levee crest computed by 2-dimensional dynamic coupled analyses and LPIs based on the results of 1-dimensional seismic response analyses was investigated. In connection with this correlation, as a result of examination of the correlation between LPI and the seismic vulnerability of the levee, it was concluded that the method for evaluation of the seismic vulnerability of the Korean river levee using LPI is applicable.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.101-104
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• 2005

This study is to develop detailing guidelines based on ductility demand for reinforced concrete bridge columns in areas of low to moderate seismicity. The current seismic design criteria of the Korea Design Specifications for Highway Bridge (KDSHB 2005) adopted the seismic design concept and requirements of the AASHTO specifications. In order to obtain full ductile behavior under seismic loads, i.e. when applied seismic force is larger than design flexural strength of column section, a response modification factor (R=3 or 5) is used. In moderate seismicity regions, however, adopting the full ductility design concept sometimes results in construction problems due to reinforcement congestion. The objective of this paper is to suggest a new simplified seismic design of reinforced concrete bridge columns for moderate seismicity regions.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.316-321
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• 2002

The current seismic design criteria of the Korea Design Specifications for Highway Bridge (KDSHB 2000) adopted the seismic design concept and requirements of the AASHTO specifications. In order to obtain full ductile behavior under seismic loads, i.e. when applied seismic force is larger than design flexural strength of column section, a response modification factor is used. For the moderate seismicity regions, a design based on required ductility and required transverse reinforcement might be a reasonable approach. Ductility demand design or performance based design might be an appropriate approach especially for regions of moderate seismic risk. The procedure and application of this design approach are presented in this paper.

• Tunnel and Underground Space
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• v.11 no.2
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• pp.120-121
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• 2001

The purpose of this study is to investigate concrete flaw using seismic first arrival and various inversion method. Seismic wave propagation was calculated using finite element method in theoretical modelling and tomogram was made using various inversion methods in theoretical and experimental modelling. Five steps of seismic first arrival were selected from FEM results and these data were used to calculate seismic velocity section. According to the results, exact seismic first arrival picking method was proposed and experimental modelling was conducted.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.521-526
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• 2002

The seismic performance of structural walls subjected to the cyclic lateral loads are influenced by various factors, like sectional shape, aspect ratio, reinforcement ratio, arrangement of reinforcement, and axial load ratio etc. In this research, reinforced concrete structural walls with the T-shaped cross section were selected. The seismic performance of T-shaped wall was affected by the many (actors because T-shaped wall is irregular wall composed to two rectangular walls. Especially the seismic performance of T-shaped wall varies with the flange condition and the various factors including the flange condition were determined. Therefore, the objective of this study is to understand the factors to improve seismic performance of RC T-shaded tv using sectional analysis.

• Structural Engineering and Mechanics
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• v.33 no.2
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• pp.113-136
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• 2009

The seismic induced interaction between multistory structures with unequal story heights (inter-story pounding) is studied taking into account the local response of the exterior beam-column joints. Although several parameters that influence the structural pounding have been studied sofar, the role of the joints local inelastic behaviour has not been yet investigated in the literature as key parameter for the pounding problem. Moreover, the influence of the infill panels as an additional parameter for the local damage effect of the joints on the inter-story pounding phenomenon is examined. Thirty six interaction cases between a multistory frame structure and an adjacent shorter and stiffer structure are studied for two different seismic excitations. The results are focused: (a) on the local response of the critical external column of the multistory structure that suffers the hit from the slab of the adjacent shorter structure, and (b) on the local response of the exterior beam-column joints of the multistory structure. Results of this investigation demonstrate that the possible local inelastic response of the exterior joints may be in some cases beneficial for the seismic behaviour of the critical column that suffers the impact. However, in all the examined cases the developing demands for deformation of the exterior joints are substantially increased and severe damages can be observed due to the pounding effect. The presence of the masonry infill panels has also been proved as an important parameter for the response of the exterior beam-column joints and thus for the safety of the building. Nevertheless, in all the examined inter-story pounding cases the presence of the infills was not enough for the total amelioration of the excessive demands for shear and ductility of the column that suffers the impact.