Seong-Hoon Jeong | Inha University (original) (raw)
Papers by Seong-Hoon Jeong
Journal of the Earthquake Engineering Society of Korea, 2011
>> A simple model for reinforced concrete shear walls with boundary elements is proposed, which i... more >> A simple model for reinforced concrete shear walls with boundary elements is proposed, which is a macro-model composed of spring elements representing flexure and shear behaviors. The flexural behaviour is represented by vertical springs at the wall ends, where the moment strength and rotational capacity of the wall are based on section analysis. The shear behaviour is represented by a horizontal spring at the wall center, where the key parameters for the shear behavior are based on the flexural behaviour since the shear walls with boundary elements are governed by the flexure. The proposed model was prepared with the results of hysteretic tests of the shear walls, and then the reliability of the hysteretic rule and variables was investigated by nonlinear dynamic analyses. Using parametric study with nonlinear dynamic analyses, the effect of the variables on demand and capacity, which are major parameters in seismic performance evaluation, are investigated. Results show that the measured and calculated shear forces versus the shear distortion relationships are slightly different, but the global response is well simulated. Furthermore, the demand and capacity are also changed in a similar way to the change in the major parameters so that the proposed model may be appropriate for reinforced concrete shear walls with boundary elements.
A methodology for the derivation of fragility curves for structures with plan irregularities is p... more A methodology for the derivation of fragility curves for structures with plan irregularities is presented herein. In order to characterize the damage state of irregular structures, a spatial (3D) damage index is formulated and employed as the damage characterization measure. The procedure is illustrated through a reference derivation of fragility curves for an irregular RC building under bidirectional earthquake loadings. Via the comparison between fragility curves derived by the spatial and the previously-existing damage indices, it is shown that employing the latter for the fragility analysis of irregular structures may be inaccurate and even unconservative.
Journal of Vibroengineering
Reinforced concrete shear wall is one of the most effective members during severe lateral loads e... more Reinforced concrete shear wall is one of the most effective members during severe lateral loads especially in earthquakes and winds. Extensive researches, both analytical and experimental, have been carried out to study the behavior of reinforced concrete (RC) shear walls. Predicting inelastic response of RC walls and wall systems requires accurate, effective, and robust analytical model that incorporate important material characteristics and behavioral response features. In this study, a modeling method using fiber and spring elements is developed to capture inelastic responses of an RC shear wall. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The parameters of the shear spring that represent strength and stiffness degradation, pinching, and slip are determined based on analysis results from a detailed finite element method (FEM) model. The relia...
Journal of Vibroengineering, 2016
Seismic provisions have utilized design eccentricities to reduce planar irregularities in lateral... more Seismic provisions have utilized design eccentricities to reduce planar irregularities in lateral stiffness of buildings. In calculating a design eccentricity, the torsional amplification factor may be applied either to accidental eccentricity or to both inherent and accidental eccentricities according to design codes. In this paper, different code provisions and their impact on torsional responses of buildings are investigated using example buildings with various aspect ratios and inherent eccentricities. It was found that the design eccentricity in KBC-2009 using torsional amplification factor for only accidental eccentricity reflects the dynamic magnification more accurately than that in KBC-2006 using this factor for both inherent and accidental eccentricity. And dynamic magnification of a torsionally imbalanced building is affected by the size of seismic design force of response spectrum analysis than design eccentricity of equivalent static analysis in KBC-2009. In other words...
MAE CENTER TEAM REPORT CONTRIBUTIONS Amr S. Elnashai, planning and initial management, lead on st... more MAE CENTER TEAM REPORT CONTRIBUTIONS Amr S. Elnashai, planning and initial management, lead on structural engineering field investigations, case study on Cathedral of Talca, executive summary and conclusions. Bora Gencturk, logistical trip and team management, coordinator of data collection, coordinator of complete report, case study on Odontology building, overview, engineering seismology, structural engineering (effects on buildings and historical structures). Oh-Sung Kwon, lead on structural engineering and case study analyses, case study on Paso Cladio Arrau, structural engineering (regional damage description and statistics, effects on bridges). Imad L. Al-Qadi, lead on transportation networks, roads and embankments. Youssef Hashash, lead on geotechnical engineering, engineering seismology. Jefferey R. Roesler, planning and initial management, lead on communications with researchers from Chilean institutions, transportation networks, roads and embankments. Sung-Jig Kim, strong ground motion, case study on Odontology building. Seong-Hoon Jeong, case study on Las Mercedes Bridge. Jazalyn Dukes, seismic fragility analysis of Las Mercedes Bridge, socioeconomic features and impact on communications. Angharad Valdivia, lead on communications during field mission, socioeconomic features and impact on communications. v TABLE OF CONTENTS MAE CENTER TEAM REPORT CONTRIBUTIONS .
Journal of the Earthquake Engineering Society of Korea, 2013
In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification f... more In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification factor (TAF), and the inherent and accidental eccentricities. When a structure of less than 6-stories and assigned to seismic design category C or D is designed using equivalent static analysis method, both KBC-2006 and KBC-2009 use the TAF but apply different calculation methods for the of design eccentricity. The design eccentricity in KBC-2006 is calculated by multiplying the sum of inherent eccentricity and accidental eccentricity at each level by a TAF but that in KBC-2009 is calculated by multiplying only the accidental eccentricity by a TAF. In this paper, the damage indices of a building with planar structural irregularity designed by different design eccentricities are compared and the relationship between the earthquake damage and design eccentricity of the building is evaluated. On the basis of this study, the increment of design eccentricity results in the decrement of final eccentricity and global damage index of structure. It is observed that design eccentricity in KBC-2006 reduces the vulnerability of torsional irregular building compared to design eccentricity in KBC-2009.
Journal of the Earthquake Engineering Society of Korea, 2013
Due to a high level of system ductility, steel moment resisting frames have been widely used for ... more Due to a high level of system ductility, steel moment resisting frames have been widely used for lateral force resisting structural systems in high seismic zones. Earthquake field investigations after Northridge earthquake in 1994 and Kobe earthquake in 1995 have reported that many steel moment resisting frames designed before 1990's had suffered significant damages and structural collapse. In this research, seismic performance assessment of steel moment resisting frames designed in accordance with the previous seismic provisions before 1990's was performed. Buckling-restrained braces and shear walls are considered for seismic retrofit of the reference buildings. Increasing stiffness and strength of the buildings using buckling-restrained braces and shear walls are considered as options to rehabilitate the damaged buildings. Probabilistic seismic performance assessment using fragility analysis results is used for the criteria for determining an appropriate seismic retrofit strategy. The fragility contour method can be used to provide an intial guideline to structural engineers when various structural retrofit options for the damaged buildings are available.
Journal of the Earthquake Engineering Society of Korea, 2010
>> This study presents seismic responses of 5-story reinforced concrete structures retrofitted wi... more >> This study presents seismic responses of 5-story reinforced concrete structures retrofitted with the bucklingrestrained braces using a time-dependent element. The time-dependent element having birth and death times can freely be activated within the user defined time intervals during the time history analysis. The buckling-restrained brace that showed the largest energy dissipation capacity among the test specimens in previous research was used for retrofitting the RC buildings in this study. It was assumed that the first story of the damaged building under the first earthquake was retrofitted with the buckling-restrained braces considered as the time-dependent element before the second of the successive earthquakes occurs. Under this assumption, this paper compares seismic responses of the RC structures with the time-dependent element subjected to the successive earthquake. Subjected to the second earthquake, it was observed that activation of the BRB systems largely decreases deformation of the moment frame where the damage was concentrated under the first earthquake. However, damages to the shear wall systems were increased after activation of the BRB systems. Since the cumulative damages of the shear wall systems were infinitesimal compared with the retrofit effect of the moment frame, the BRB system was effective under the successive earthquake.
Journal of the Korea Concrete Institute, 2012
In this study, fiber elements and a spring are used to build a reinforced concrete shear wall mod... more In this study, fiber elements and a spring are used to build a reinforced concrete shear wall model. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The spring parameters representing strength and stiffness degradation, pinching, and slip were determined by comparing behaviors of fiber element and VecTor2 results. 'Pinching4' model in OpenSees is used for shear spring. The parameter selecting process for shear spring is a complicated and time consuming process. To study the applicability of the fiber element, reinforced concrete buildings containing a shear wall are evaluated using nonlinear dynamic analysis with various wall aspect ratio (H/L), various beam heights, and stiffness and flexural strength of beam and wall ratios. The aspect ratio of the wall showed distinct difference in IDR (interstory drift ratio) of the models with and without spring. On the other hand, the height of beam and ratio of stiffness and flexural strength of beam and wall did not show clear relation.
Engineering Structures, 2012
Fragility analyses are conducted in this study to evaluate the relative seismic safety margins of... more Fragility analyses are conducted in this study to evaluate the relative seismic safety margins of seismic code-designed multi-story reinforced concrete (RC) buildings with varying input motion intensity, ductility level and configuration. Structural variations are accounted for by using twelve buildings [13] with diverse structural systems, heights and ductile detailing. The design peak ground acceleration (PGA) is also varied. The reference structures also include regular and irregular buildings in order to cover a wide spectrum of contemporary mid-rise buildings. Incremental dynamic analyses (IDAs) are deployed using the twelve inelastic fiber-based simulation models of the reference structures and sixty natural ground motions recorded on different soil conditions with a wide range of spectral amplifications. The regression analyses of the selected response quantities show that the soil condition has a marginal effect on the demand-ground motion intensity relationships when adopting spectral acceleration to characterize the ground shaking intensity. The damage state probabilities of wall-frame structures designed to high PGA and ductility levels do not satisfactorily achieve the most favorable safety objectives. Fragilities are reduced by decreasing the design PGA due to the higher contribution of gravity loads to the details of the building design. Using extensive results from twelve buildings subjected to sixty ground motions, a relationship is proposed to enable the quantifying of the Life Safety limit state probabilities of codecompliant mid-rise RC buildings.
Engineering Structures, 2007
Analytical probabilistic fragility studies require extensive computer simulations to account for ... more Analytical probabilistic fragility studies require extensive computer simulations to account for the randomness in both input motion and response characteristics. In this study, an approach whereby a set of fragility relationships with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility is presented. An exact solution for a generalized single degree of freedom system is developed and employed to construct a Response Database of coefficients describing commonly used log-normal fragility relationships. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility relationships for various limit states can be constructed without recourse to further simulation. The uncertainty associated with modeling simplifications is quantified by conducting comparisons between the proposed approach and detailed multi-degree of freedom (MDOF) systems. Application examples are given to demonstrate the efficiency of the proposed approach.
Analytical probabilistic fragility studies require extensive computer simulations to account for ... more Analytical probabilistic fragility studies require extensive computer simulations to account for the randomness in both input motion and response characteristics. In this study, an approach whereby a set of fragility relationships with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility is presented. An exact solution for a generalized single degree of freedom system is developed and employed to construct a Response Database of coefficients describing commonly used log-normal fragility relationships. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility relationships for various limit states can be constructed without recourse to further simulation. The uncertainty associated with modeling simplifications is quantified by conducting comparisons between the proposed approach and detailed multi-degree of freedom (MDOF) systems. Application examples are given to demonstrate the efficiency of the proposed approach.
Journal of the Earthquake Engineering Society of Korea, 2011
>> A simple model for reinforced concrete shear walls with boundary elements is proposed, which i... more >> A simple model for reinforced concrete shear walls with boundary elements is proposed, which is a macro-model composed of spring elements representing flexure and shear behaviors. The flexural behaviour is represented by vertical springs at the wall ends, where the moment strength and rotational capacity of the wall are based on section analysis. The shear behaviour is represented by a horizontal spring at the wall center, where the key parameters for the shear behavior are based on the flexural behaviour since the shear walls with boundary elements are governed by the flexure. The proposed model was prepared with the results of hysteretic tests of the shear walls, and then the reliability of the hysteretic rule and variables was investigated by nonlinear dynamic analyses. Using parametric study with nonlinear dynamic analyses, the effect of the variables on demand and capacity, which are major parameters in seismic performance evaluation, are investigated. Results show that the measured and calculated shear forces versus the shear distortion relationships are slightly different, but the global response is well simulated. Furthermore, the demand and capacity are also changed in a similar way to the change in the major parameters so that the proposed model may be appropriate for reinforced concrete shear walls with boundary elements.
A methodology for the derivation of fragility curves for structures with plan irregularities is p... more A methodology for the derivation of fragility curves for structures with plan irregularities is presented herein. In order to characterize the damage state of irregular structures, a spatial (3D) damage index is formulated and employed as the damage characterization measure. The procedure is illustrated through a reference derivation of fragility curves for an irregular RC building under bidirectional earthquake loadings. Via the comparison between fragility curves derived by the spatial and the previously-existing damage indices, it is shown that employing the latter for the fragility analysis of irregular structures may be inaccurate and even unconservative.
Journal of Vibroengineering
Reinforced concrete shear wall is one of the most effective members during severe lateral loads e... more Reinforced concrete shear wall is one of the most effective members during severe lateral loads especially in earthquakes and winds. Extensive researches, both analytical and experimental, have been carried out to study the behavior of reinforced concrete (RC) shear walls. Predicting inelastic response of RC walls and wall systems requires accurate, effective, and robust analytical model that incorporate important material characteristics and behavioral response features. In this study, a modeling method using fiber and spring elements is developed to capture inelastic responses of an RC shear wall. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The parameters of the shear spring that represent strength and stiffness degradation, pinching, and slip are determined based on analysis results from a detailed finite element method (FEM) model. The relia...
Journal of Vibroengineering, 2016
Seismic provisions have utilized design eccentricities to reduce planar irregularities in lateral... more Seismic provisions have utilized design eccentricities to reduce planar irregularities in lateral stiffness of buildings. In calculating a design eccentricity, the torsional amplification factor may be applied either to accidental eccentricity or to both inherent and accidental eccentricities according to design codes. In this paper, different code provisions and their impact on torsional responses of buildings are investigated using example buildings with various aspect ratios and inherent eccentricities. It was found that the design eccentricity in KBC-2009 using torsional amplification factor for only accidental eccentricity reflects the dynamic magnification more accurately than that in KBC-2006 using this factor for both inherent and accidental eccentricity. And dynamic magnification of a torsionally imbalanced building is affected by the size of seismic design force of response spectrum analysis than design eccentricity of equivalent static analysis in KBC-2009. In other words...
MAE CENTER TEAM REPORT CONTRIBUTIONS Amr S. Elnashai, planning and initial management, lead on st... more MAE CENTER TEAM REPORT CONTRIBUTIONS Amr S. Elnashai, planning and initial management, lead on structural engineering field investigations, case study on Cathedral of Talca, executive summary and conclusions. Bora Gencturk, logistical trip and team management, coordinator of data collection, coordinator of complete report, case study on Odontology building, overview, engineering seismology, structural engineering (effects on buildings and historical structures). Oh-Sung Kwon, lead on structural engineering and case study analyses, case study on Paso Cladio Arrau, structural engineering (regional damage description and statistics, effects on bridges). Imad L. Al-Qadi, lead on transportation networks, roads and embankments. Youssef Hashash, lead on geotechnical engineering, engineering seismology. Jefferey R. Roesler, planning and initial management, lead on communications with researchers from Chilean institutions, transportation networks, roads and embankments. Sung-Jig Kim, strong ground motion, case study on Odontology building. Seong-Hoon Jeong, case study on Las Mercedes Bridge. Jazalyn Dukes, seismic fragility analysis of Las Mercedes Bridge, socioeconomic features and impact on communications. Angharad Valdivia, lead on communications during field mission, socioeconomic features and impact on communications. v TABLE OF CONTENTS MAE CENTER TEAM REPORT CONTRIBUTIONS .
Journal of the Earthquake Engineering Society of Korea, 2013
In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification f... more In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification factor (TAF), and the inherent and accidental eccentricities. When a structure of less than 6-stories and assigned to seismic design category C or D is designed using equivalent static analysis method, both KBC-2006 and KBC-2009 use the TAF but apply different calculation methods for the of design eccentricity. The design eccentricity in KBC-2006 is calculated by multiplying the sum of inherent eccentricity and accidental eccentricity at each level by a TAF but that in KBC-2009 is calculated by multiplying only the accidental eccentricity by a TAF. In this paper, the damage indices of a building with planar structural irregularity designed by different design eccentricities are compared and the relationship between the earthquake damage and design eccentricity of the building is evaluated. On the basis of this study, the increment of design eccentricity results in the decrement of final eccentricity and global damage index of structure. It is observed that design eccentricity in KBC-2006 reduces the vulnerability of torsional irregular building compared to design eccentricity in KBC-2009.
Journal of the Earthquake Engineering Society of Korea, 2013
Due to a high level of system ductility, steel moment resisting frames have been widely used for ... more Due to a high level of system ductility, steel moment resisting frames have been widely used for lateral force resisting structural systems in high seismic zones. Earthquake field investigations after Northridge earthquake in 1994 and Kobe earthquake in 1995 have reported that many steel moment resisting frames designed before 1990's had suffered significant damages and structural collapse. In this research, seismic performance assessment of steel moment resisting frames designed in accordance with the previous seismic provisions before 1990's was performed. Buckling-restrained braces and shear walls are considered for seismic retrofit of the reference buildings. Increasing stiffness and strength of the buildings using buckling-restrained braces and shear walls are considered as options to rehabilitate the damaged buildings. Probabilistic seismic performance assessment using fragility analysis results is used for the criteria for determining an appropriate seismic retrofit strategy. The fragility contour method can be used to provide an intial guideline to structural engineers when various structural retrofit options for the damaged buildings are available.
Journal of the Earthquake Engineering Society of Korea, 2010
>> This study presents seismic responses of 5-story reinforced concrete structures retrofitted wi... more >> This study presents seismic responses of 5-story reinforced concrete structures retrofitted with the bucklingrestrained braces using a time-dependent element. The time-dependent element having birth and death times can freely be activated within the user defined time intervals during the time history analysis. The buckling-restrained brace that showed the largest energy dissipation capacity among the test specimens in previous research was used for retrofitting the RC buildings in this study. It was assumed that the first story of the damaged building under the first earthquake was retrofitted with the buckling-restrained braces considered as the time-dependent element before the second of the successive earthquakes occurs. Under this assumption, this paper compares seismic responses of the RC structures with the time-dependent element subjected to the successive earthquake. Subjected to the second earthquake, it was observed that activation of the BRB systems largely decreases deformation of the moment frame where the damage was concentrated under the first earthquake. However, damages to the shear wall systems were increased after activation of the BRB systems. Since the cumulative damages of the shear wall systems were infinitesimal compared with the retrofit effect of the moment frame, the BRB system was effective under the successive earthquake.
Journal of the Korea Concrete Institute, 2012
In this study, fiber elements and a spring are used to build a reinforced concrete shear wall mod... more In this study, fiber elements and a spring are used to build a reinforced concrete shear wall model. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The spring parameters representing strength and stiffness degradation, pinching, and slip were determined by comparing behaviors of fiber element and VecTor2 results. 'Pinching4' model in OpenSees is used for shear spring. The parameter selecting process for shear spring is a complicated and time consuming process. To study the applicability of the fiber element, reinforced concrete buildings containing a shear wall are evaluated using nonlinear dynamic analysis with various wall aspect ratio (H/L), various beam heights, and stiffness and flexural strength of beam and wall ratios. The aspect ratio of the wall showed distinct difference in IDR (interstory drift ratio) of the models with and without spring. On the other hand, the height of beam and ratio of stiffness and flexural strength of beam and wall did not show clear relation.
Engineering Structures, 2012
Fragility analyses are conducted in this study to evaluate the relative seismic safety margins of... more Fragility analyses are conducted in this study to evaluate the relative seismic safety margins of seismic code-designed multi-story reinforced concrete (RC) buildings with varying input motion intensity, ductility level and configuration. Structural variations are accounted for by using twelve buildings [13] with diverse structural systems, heights and ductile detailing. The design peak ground acceleration (PGA) is also varied. The reference structures also include regular and irregular buildings in order to cover a wide spectrum of contemporary mid-rise buildings. Incremental dynamic analyses (IDAs) are deployed using the twelve inelastic fiber-based simulation models of the reference structures and sixty natural ground motions recorded on different soil conditions with a wide range of spectral amplifications. The regression analyses of the selected response quantities show that the soil condition has a marginal effect on the demand-ground motion intensity relationships when adopting spectral acceleration to characterize the ground shaking intensity. The damage state probabilities of wall-frame structures designed to high PGA and ductility levels do not satisfactorily achieve the most favorable safety objectives. Fragilities are reduced by decreasing the design PGA due to the higher contribution of gravity loads to the details of the building design. Using extensive results from twelve buildings subjected to sixty ground motions, a relationship is proposed to enable the quantifying of the Life Safety limit state probabilities of codecompliant mid-rise RC buildings.
Engineering Structures, 2007
Analytical probabilistic fragility studies require extensive computer simulations to account for ... more Analytical probabilistic fragility studies require extensive computer simulations to account for the randomness in both input motion and response characteristics. In this study, an approach whereby a set of fragility relationships with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility is presented. An exact solution for a generalized single degree of freedom system is developed and employed to construct a Response Database of coefficients describing commonly used log-normal fragility relationships. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility relationships for various limit states can be constructed without recourse to further simulation. The uncertainty associated with modeling simplifications is quantified by conducting comparisons between the proposed approach and detailed multi-degree of freedom (MDOF) systems. Application examples are given to demonstrate the efficiency of the proposed approach.
Analytical probabilistic fragility studies require extensive computer simulations to account for ... more Analytical probabilistic fragility studies require extensive computer simulations to account for the randomness in both input motion and response characteristics. In this study, an approach whereby a set of fragility relationships with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility is presented. An exact solution for a generalized single degree of freedom system is developed and employed to construct a Response Database of coefficients describing commonly used log-normal fragility relationships. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility relationships for various limit states can be constructed without recourse to further simulation. The uncertainty associated with modeling simplifications is quantified by conducting comparisons between the proposed approach and detailed multi-degree of freedom (MDOF) systems. Application examples are given to demonstrate the efficiency of the proposed approach.