The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Guolin Wang - One of the best experts on this subject based on the ideXlab platform.
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seismic Retrofit of exterior rc beam column joints with bonded cfrp reinforcement an experimental study
Composite Structures, 2019Co-Authors: Guolin WangAbstract:Abstract This paper presents an experimental study on the strengthening of seismically deficient RC beam-column joints using carbon fiber reinforced polymer (CFRP). Six exterior RC beam-column joint specimens were tested to identify an effective Method for improving the seismic performance of such joints in terms of their lateral strength and ductility. These six specimens included one non-seismically designed specimen, one seismically designed specimen, and four specimens Retrofitted using different schemes. In these schemes, both externally bonded CFRP sheets and near-surface mounted (NSM) CFRP strips were explored as strengthening options. The test results showed that by adding CFRP reinforcement, the seismic performance of a seismically deficient beam-column joint can be significantly improved. In particular, the use of NSM CFRP strips in beams and joints was found to effectively relocate the plastic hinge away from the joint region, thereby leading to a ductile failure mode (beam flexural failure), which demonstrates the effectiveness of this seismic Retrofit Method. A good understanding of the hinge relocation mechanisms has been achieved through extensive and detailed strain measurement during the tests.
Hyo Seon Park - One of the best experts on this subject based on the ideXlab platform.
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Optimal seismic Retrofit Method for reinforced concrete columns with wing walls
Engineering Structures, 2020Co-Authors: Yousok Kim, Su A. Lim, Hyo Seon ParkAbstract:Abstract Seismic Retrofit of reinforced concrete (RC) columns using wing walls can be used to improve the shear and flexural strength of the column through a relatively simple process. However, the feasibility and efficiency of the seismic Retrofitting of RC frames with wing walls heavily depends on the selection of number of columns to be Retrofitted, the cross-sectional dimensions of wing walls, and the quantity of re-bars of the wing wall. In this study, an optimal seismic Retrofit design Method is proposed to minimize not only the initial Retrofit cost but also the earthquake-induced damage expected during the life cycle of the building. The seismic performance of structures before and after the application of the Retrofit has been verified with the comparison of four response parameters: pushover curves, the inter-storey drift ratios, the energy dissipation capacities, and failure modes. The proposed Retrofit Method is applied to seismic Retrofit of a six-storey RC building example and an actual RC building structure in use. For the Retrofit of actual building structure, with an initial Retrofit weight of 70.85 kN, which corresponds to 1.85% of the weight of the non-Retrofitted building, the energy dissipation capacity was increase by 3.02 times and the life cycle cost (LCC) of the Retrofit was reduced to 69.47% of the required LCC for the non-Retrofitted building. In addition, it has been confirmed that no storey collapse occurred in collapse prevention level, which indicates the most severe failure mechanism of a structure due to an earthquake.
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Multi-objective seismic Retrofit Method for using FRP jackets in shear-critical reinforced concrete frames
Composites Part B: Engineering, 2014Co-Authors: Woon Choi, Yousok Kim, Hyo Seon ParkAbstract:Abstract Many research studies have been conducted on seismic Retrofits of existing reinforced concrete (RC) frames with fiber–reinforced polymer (FRP) jackets. Although existing RC columns are vulnerable to shear failure because of insufficient transverse reinforcement and deficient seismic details, little research exists on the reinforcement locations and FRP reinforcement level required to prevent column shear failure. In this paper, the optimal seismic Retrofit Method that uses FRP jackets for shear-critical RC frames is presented. This optimal Method uses non-dominated sorting genetic algorithm-II (NSGA-II) to optimize the two conflicting objective functions of the Retrofit cost as well as the seismic performance, simultaneously. To minimize the Retrofit cost and maximize the seismic performance of a structure, this optimal Method minimizes the amount of FRP required and the coefficient of variation of inter-story drift ratios while satisfying the constraint conditions on the shear failure prevention, maximum inter-story drift ratio, and maximum compressive strain of concrete. Both the flexural reinforcement Method and shear reinforcement Method of FRP jackets are adopted to strengthen the flexural capacity and shear strength of columns, respectively. The two reinforcement Methods are applied sequentially to minimize the total amount of FRP material required. The proposed Method is applied to 3-story RC frame and the optimal Retrofit schemes that suggest the reinforcement locations and the number of FRP reinforcement plies are obtained.
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Performance-Based Multiobjective Optimal Seismic Retrofit Method for a Steel Moment-Resisting Frame Considering the Life-Cycle Cost
Mathematical Problems in Engineering, 2014Co-Authors: Hyo Seon Park, Woon Choi, Dong Chul Lee, Yousok KimAbstract:This study proposes a performance-based multiobjective optimization seismic Retrofit Method for steel moment-resisting frames. The brittle joints of pre-Northridge steel moment-resisting frames are Retrofitted to achieve ductility; the Method involves determining the position and number of connections to be Retrofitted. The optimal solution is determined by applying the nondominated sorting genetic algorithm-II (NSGA-II), which acts as a multiobjective seismic Retrofit optimization technique. As objective functions, the initial cost for the connection Retrofit and lifetime seismic damage cost were selected, and a seismic performance level below the 5% interstory drift ratio was employed as a constraint condition. The proposed Method was applied to the SAC benchmark three- and nine-story buildings, and several Pareto solutions were obtained. The optimized Retrofit solutions indicated that the lifetime seismic damage cost decreased as the initial Retrofit cost increased. Although every Pareto solution existed within a seismic performance boundary set by a constraint function, the seismic performance tended to increase with the initial Retrofit cost. Analysis and economic assessment of the relations among the initial Retrofit cost, lifetime seismic damage cost, total cost, and seismic performance of the derived Pareto solution allow building owners to make seismic Retrofit decisions more rationally.
Yousok Kim - One of the best experts on this subject based on the ideXlab platform.
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Optimal seismic Retrofit Method for reinforced concrete columns with wing walls
Engineering Structures, 2020Co-Authors: Yousok Kim, Su A. Lim, Hyo Seon ParkAbstract:Abstract Seismic Retrofit of reinforced concrete (RC) columns using wing walls can be used to improve the shear and flexural strength of the column through a relatively simple process. However, the feasibility and efficiency of the seismic Retrofitting of RC frames with wing walls heavily depends on the selection of number of columns to be Retrofitted, the cross-sectional dimensions of wing walls, and the quantity of re-bars of the wing wall. In this study, an optimal seismic Retrofit design Method is proposed to minimize not only the initial Retrofit cost but also the earthquake-induced damage expected during the life cycle of the building. The seismic performance of structures before and after the application of the Retrofit has been verified with the comparison of four response parameters: pushover curves, the inter-storey drift ratios, the energy dissipation capacities, and failure modes. The proposed Retrofit Method is applied to seismic Retrofit of a six-storey RC building example and an actual RC building structure in use. For the Retrofit of actual building structure, with an initial Retrofit weight of 70.85 kN, which corresponds to 1.85% of the weight of the non-Retrofitted building, the energy dissipation capacity was increase by 3.02 times and the life cycle cost (LCC) of the Retrofit was reduced to 69.47% of the required LCC for the non-Retrofitted building. In addition, it has been confirmed that no storey collapse occurred in collapse prevention level, which indicates the most severe failure mechanism of a structure due to an earthquake.
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Multi-objective seismic Retrofit Method for using FRP jackets in shear-critical reinforced concrete frames
Composites Part B: Engineering, 2014Co-Authors: Woon Choi, Yousok Kim, Hyo Seon ParkAbstract:Abstract Many research studies have been conducted on seismic Retrofits of existing reinforced concrete (RC) frames with fiber–reinforced polymer (FRP) jackets. Although existing RC columns are vulnerable to shear failure because of insufficient transverse reinforcement and deficient seismic details, little research exists on the reinforcement locations and FRP reinforcement level required to prevent column shear failure. In this paper, the optimal seismic Retrofit Method that uses FRP jackets for shear-critical RC frames is presented. This optimal Method uses non-dominated sorting genetic algorithm-II (NSGA-II) to optimize the two conflicting objective functions of the Retrofit cost as well as the seismic performance, simultaneously. To minimize the Retrofit cost and maximize the seismic performance of a structure, this optimal Method minimizes the amount of FRP required and the coefficient of variation of inter-story drift ratios while satisfying the constraint conditions on the shear failure prevention, maximum inter-story drift ratio, and maximum compressive strain of concrete. Both the flexural reinforcement Method and shear reinforcement Method of FRP jackets are adopted to strengthen the flexural capacity and shear strength of columns, respectively. The two reinforcement Methods are applied sequentially to minimize the total amount of FRP material required. The proposed Method is applied to 3-story RC frame and the optimal Retrofit schemes that suggest the reinforcement locations and the number of FRP reinforcement plies are obtained.
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Performance-Based Multiobjective Optimal Seismic Retrofit Method for a Steel Moment-Resisting Frame Considering the Life-Cycle Cost
Mathematical Problems in Engineering, 2014Co-Authors: Hyo Seon Park, Woon Choi, Dong Chul Lee, Yousok KimAbstract:This study proposes a performance-based multiobjective optimization seismic Retrofit Method for steel moment-resisting frames. The brittle joints of pre-Northridge steel moment-resisting frames are Retrofitted to achieve ductility; the Method involves determining the position and number of connections to be Retrofitted. The optimal solution is determined by applying the nondominated sorting genetic algorithm-II (NSGA-II), which acts as a multiobjective seismic Retrofit optimization technique. As objective functions, the initial cost for the connection Retrofit and lifetime seismic damage cost were selected, and a seismic performance level below the 5% interstory drift ratio was employed as a constraint condition. The proposed Method was applied to the SAC benchmark three- and nine-story buildings, and several Pareto solutions were obtained. The optimized Retrofit solutions indicated that the lifetime seismic damage cost decreased as the initial Retrofit cost increased. Although every Pareto solution existed within a seismic performance boundary set by a constraint function, the seismic performance tended to increase with the initial Retrofit cost. Analysis and economic assessment of the relations among the initial Retrofit cost, lifetime seismic damage cost, total cost, and seismic performance of the derived Pareto solution allow building owners to make seismic Retrofit decisions more rationally.
Konrad Hungerbühler - One of the best experts on this subject based on the ideXlab platform.
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Systematic Retrofit Method for Chemical Batch Processes Using Indicators, Heuristics, and Process Models
Industrial & Engineering Chemistry Research, 2008Co-Authors: Levente L. Simon, Neil Osterwalder, Ulrich Fischer, Konrad HungerbühlerAbstract:This work presents a novel systematic indicator, heuristics, and process model based decision support framework for Retrofitting chemical batch processes. The systematic framework considers the ide...
Woon Choi - One of the best experts on this subject based on the ideXlab platform.
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Multi-objective seismic Retrofit Method for using FRP jackets in shear-critical reinforced concrete frames
Composites Part B: Engineering, 2014Co-Authors: Woon Choi, Yousok Kim, Hyo Seon ParkAbstract:Abstract Many research studies have been conducted on seismic Retrofits of existing reinforced concrete (RC) frames with fiber–reinforced polymer (FRP) jackets. Although existing RC columns are vulnerable to shear failure because of insufficient transverse reinforcement and deficient seismic details, little research exists on the reinforcement locations and FRP reinforcement level required to prevent column shear failure. In this paper, the optimal seismic Retrofit Method that uses FRP jackets for shear-critical RC frames is presented. This optimal Method uses non-dominated sorting genetic algorithm-II (NSGA-II) to optimize the two conflicting objective functions of the Retrofit cost as well as the seismic performance, simultaneously. To minimize the Retrofit cost and maximize the seismic performance of a structure, this optimal Method minimizes the amount of FRP required and the coefficient of variation of inter-story drift ratios while satisfying the constraint conditions on the shear failure prevention, maximum inter-story drift ratio, and maximum compressive strain of concrete. Both the flexural reinforcement Method and shear reinforcement Method of FRP jackets are adopted to strengthen the flexural capacity and shear strength of columns, respectively. The two reinforcement Methods are applied sequentially to minimize the total amount of FRP material required. The proposed Method is applied to 3-story RC frame and the optimal Retrofit schemes that suggest the reinforcement locations and the number of FRP reinforcement plies are obtained.
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Performance-Based Multiobjective Optimal Seismic Retrofit Method for a Steel Moment-Resisting Frame Considering the Life-Cycle Cost
Mathematical Problems in Engineering, 2014Co-Authors: Hyo Seon Park, Woon Choi, Dong Chul Lee, Yousok KimAbstract:This study proposes a performance-based multiobjective optimization seismic Retrofit Method for steel moment-resisting frames. The brittle joints of pre-Northridge steel moment-resisting frames are Retrofitted to achieve ductility; the Method involves determining the position and number of connections to be Retrofitted. The optimal solution is determined by applying the nondominated sorting genetic algorithm-II (NSGA-II), which acts as a multiobjective seismic Retrofit optimization technique. As objective functions, the initial cost for the connection Retrofit and lifetime seismic damage cost were selected, and a seismic performance level below the 5% interstory drift ratio was employed as a constraint condition. The proposed Method was applied to the SAC benchmark three- and nine-story buildings, and several Pareto solutions were obtained. The optimized Retrofit solutions indicated that the lifetime seismic damage cost decreased as the initial Retrofit cost increased. Although every Pareto solution existed within a seismic performance boundary set by a constraint function, the seismic performance tended to increase with the initial Retrofit cost. Analysis and economic assessment of the relations among the initial Retrofit cost, lifetime seismic damage cost, total cost, and seismic performance of the derived Pareto solution allow building owners to make seismic Retrofit decisions more rationally.