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Nonlinear dynamic analysis is implemented to determine collapse intensity for a set of ground motions. For the nonlinear dynamic analysis, a set of 22 far-field ground motions is adopted from FEMA P695 in this study. Their event and recordings station, and site and source data are presented in Table A-4A and Table A-4B in records are ex (PEER, 2013), perpendicular of the twenty-two ed by using the procedure described in FEMA P695. records are sca Appendix A of ract FEMA P695. The 22 ground motion ed from the PEER NGA Database of which information and parameters are presented in Ta ble A-4C. Each record contains two horizontal ground motion data, so the total number is 44. Fig.7. shows the response spectra far-field record set. Ground motion Fig.7. Response Spectra of the Twenty-Two Far-Field Record Set and MCE SDC Spectrum at Dmin/Cmax

Figure 7 Nonlinear dynamic analysis is implemented to determine collapse intensity for a set of ground motions. For the nonlinear dynamic analysis, a set of 22 far-field ground motions is adopted from FEMA P695 in this study. Their event and recordings station, and site and source data are presented in Table A-4A and Table A-4B in records are ex (PEER, 2013), perpendicular of the twenty-two ed by using the procedure described in FEMA P695. records are sca Appendix A of ract FEMA P695. The 22 ground motion ed from the PEER NGA Database of which information and parameters are presented in Ta ble A-4C. Each record contains two horizontal ground motion data, so the total number is 44. Fig.7. shows the response spectra far-field record set. Ground motion Fig.7. Response Spectra of the Twenty-Two Far-Field Record Set and MCE SDC Spectrum at Dmin/Cmax

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Table 1. Seismic Design Parameters for Ordinary Shear Walls in ASCE 7 (2010) Many reinforced concrete (RC) buildings are composed of walls and frames in Korea. The walls are very effective in resisting seismic lateral force and have a role in architectural elements, such as stairways or elevator shafts, while frames resist most gravity loads. Structural engineers can therefore easily select walls as a major seismic-force-resisting system (SFRS in buildings composed of both walls and frames. Therefore, the subject of this study is related to Korean design practice for the walls in buildings. It is noted that the object of this study is limited to RC ordinary systems because the typical Korean practice is limited to the design of such systems. In addition, while there exist various design procedures, this study is focused on the equivalent lateral force (ELF) design specified in codes such as Korean Building Code (KBC) (2016) or ASCE 7 (2010) because it is the most popular and simplest way of designing the ordinary system. When structural engineers want to design ordinary shear walls in an RC wall-frame building, they should decide which option will be suitable based on their experience. If choosing BFS, then the shear walls are considered to resist 100% of the ELF design lateral load, and the frames to resist only the gravity loads. If For the design of ordinary RC shear walls as part of wall-frame buildings, one can choose one of two design options when following the codes. One can be chosen from an ordinary shear wall within the building frames system (BFS), and another can be chosen from that within the wall-frame interactive system (WFIS). Table 1. presents key seismic design parameters (response modification factor R, system over-strength factor ©,, and deflection amplification factor C,), for both options specified in ASCE 7. The differences between the two approaches are basically in the level of the R and C, factors, as well as the allowable range of the seismic design category (SDC). The design parameters in KBC are identical to those in ASCE 7 except for the relaxed allowable range. According to KBC, there is no limit for ordinary shear walls with a height of less than 60 m even at SDC D regardless of the system.
Table 1. Seismic Design Parameters for Ordinary Shear Walls in ASCE 7 (2010) Many reinforced concrete (RC) buildings are composed of walls and frames in Korea. The walls are very effective in resisting seismic lateral force and have a role in architectural elements, such as stairways or elevator shafts, while frames resist most gravity loads. Structural engineers can therefore easily select walls as a major seismic-force-resisting system (SFRS in buildings composed of both walls and frames. Therefore, the subject of this study is related to Korean design practice for the walls in buildings. It is noted that the object of this study is limited to RC ordinary systems because the typical Korean practice is limited to the design of such systems. In addition, while there exist various design procedures, this study is focused on the equivalent lateral force (ELF) design specified in codes such as Korean Building Code (KBC) (2016) or ASCE 7 (2010) because it is the most popular and simplest way of designing the ordinary system. When structural engineers want to design ordinary shear walls in an RC wall-frame building, they should decide which option will be suitable based on their experience. If choosing BFS, then the shear walls are considered to resist 100% of the ELF design lateral load, and the frames to resist only the gravity loads. If For the design of ordinary RC shear walls as part of wall-frame buildings, one can choose one of two design options when following the codes. One can be chosen from an ordinary shear wall within the building frames system (BFS), and another can be chosen from that within the wall-frame interactive system (WFIS). Table 1. presents key seismic design parameters (response modification factor R, system over-strength factor ©,, and deflection amplification factor C,), for both options specified in ASCE 7. The differences between the two approaches are basically in the level of the R and C, factors, as well as the allowable range of the seismic design category (SDC). The design parameters in KBC are identical to those in ASCE 7 except for the relaxed allowable range. According to KBC, there is no limit for ordinary shear walls with a height of less than 60 m even at SDC D regardless of the system.
moment because the flexural rigidity of the frames can absorb some overturning moments, which may result in lighter wall designs in comparison to the BFS. It can be said that the Korean design practice is similar to that for a WFIS per ASCE 7 in terms of wall design. However, in the Korean practice, a different response modification factor (R-factor) from the WFIS, which is 5.0 for the BFS, is used and no check for 75% and 25% design story shears for walls and frames, respectively, is conducted. Fig.1. Typical Floor Plan of RC Wall-Frame Building in Korea
moment because the flexural rigidity of the frames can absorb some overturning moments, which may result in lighter wall designs in comparison to the BFS. It can be said that the Korean design practice is similar to that for a WFIS per ASCE 7 in terms of wall design. However, in the Korean practice, a different response modification factor (R-factor) from the WFIS, which is 5.0 for the BFS, is used and no check for 75% and 25% design story shears for walls and frames, respectively, is conducted. Fig.1. Typical Floor Plan of RC Wall-Frame Building in Korea
Table 2. Dimensions and Reinforcement for Walls Table 3. Dimensions of Beam and Columns (Unit: mm)
Table 2. Dimensions and Reinforcement for Walls Table 3. Dimensions of Beam and Columns (Unit: mm)
Fig.2. Plan of Example Buildings (unit: mm) procedures for both options have been described in the previous chapter. The example buildings are assumed o be located at the boundary between SDC C and SDC D because RC ordinary shear walls are permitted for SDC A, B, and C in ASCE 7. The MCE spectral response acceleration parameters for short periods (Sys) and at | second (S,,,) are 0.75g and 0.30g, respectively, for the location.
Fig.2. Plan of Example Buildings (unit: mm) procedures for both options have been described in the previous chapter. The example buildings are assumed o be located at the boundary between SDC C and SDC D because RC ordinary shear walls are permitted for SDC A, B, and C in ASCE 7. The MCE spectral response acceleration parameters for short periods (Sys) and at | second (S,,,) are 0.75g and 0.30g, respectively, for the location.
The wall thickness of the KDP is smaller than that of the BFS. This is because frame action has more of an effect on absorbing the overturning moment than base shear. As shown in Fig.3.(a), there is little difference in design shear force. On the other hand, the design moment decreases significantly as shown in Fig.3.(b). This decrease could lead to a reduction in wall thickness. In the case of the KDP, the wall thickness and corresponding reinforcement are identical for both 4-m and 6-m bay lengths, as the minimum reinforcement (maximum reinforcement spacing) is enough to resist the design moment in both cases. In the case of a 4-m bay length, the difference between the two options is larger than for a 6-m bay length. This is due to whether the minimum reinforcement is applicable or not. For a 6-m bay length, on the other hand, the minimum reinforcement is applied in both options. This difference in the wall thickness affects the performance evaluation results, which will be presented later. The dimensions of beams and columns are nearly identical because they resist only gravity loads in both options.
The wall thickness of the KDP is smaller than that of the BFS. This is because frame action has more of an effect on absorbing the overturning moment than base shear. As shown in Fig.3.(a), there is little difference in design shear force. On the other hand, the design moment decreases significantly as shown in Fig.3.(b). This decrease could lead to a reduction in wall thickness. In the case of the KDP, the wall thickness and corresponding reinforcement are identical for both 4-m and 6-m bay lengths, as the minimum reinforcement (maximum reinforcement spacing) is enough to resist the design moment in both cases. In the case of a 4-m bay length, the difference between the two options is larger than for a 6-m bay length. This is due to whether the minimum reinforcement is applicable or not. For a 6-m bay length, on the other hand, the minimum reinforcement is applied in both options. This difference in the wall thickness affects the performance evaluation results, which will be presented later. The dimensions of beams and columns are nearly identical because they resist only gravity loads in both options.
Fig.5. Comparison of Cyclic Behavior of a Wall from Experiment and Analysis
Fig.5. Comparison of Cyclic Behavior of a Wall from Experiment and Analysis
the analysis model; one is a wall with a frame, while the other is only a frame. They are linked by rigid beam elements with pinned ends, so as not to transfer the bending moment while ensuring the same lateral displacement. To reflect a cracked RC section, an effective moment of inertia is used for the beams. The effective moment of inertia is taken as 30% of the gross moment of inertia for beams (similar to what is suggested in ASCE 41 (2013)). The moments of inertia for beams incorporate T-beam effects. The effective moment of inertia is not explicitly assigned in walls and columns because the fiber element can reflect the cracked section effect by itself. It is noted that all the strengths used for the models are expected values, not nominal values.
the analysis model; one is a wall with a frame, while the other is only a frame. They are linked by rigid beam elements with pinned ends, so as not to transfer the bending moment while ensuring the same lateral displacement. To reflect a cracked RC section, an effective moment of inertia is used for the beams. The effective moment of inertia is taken as 30% of the gross moment of inertia for beams (similar to what is suggested in ASCE 41 (2013)). The moments of inertia for beams incorporate T-beam effects. The effective moment of inertia is not explicitly assigned in walls and columns because the fiber element can reflect the cracked section effect by itself. It is noted that all the strengths used for the models are expected values, not nominal values.
Table 4. Results of Performance Assessment of the Example Buildings per FEMA P695
Table 4. Results of Performance Assessment of the Example Buildings per FEMA P695
Fig.8. Example of Incremental Dynamic Analysis for KDP-4m
Fig.8. Example of Incremental Dynamic Analysis for KDP-4m
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