In equivalent static nonlinear analysis and in energy-based design, the structures are generally transforrned into an equivalent SDOF system. In this study the seismic energy demands in multi story structures, such as three-, eight-, and twenty-story steel moment-resisting frames (MRF), buckling restrained braced frames (BRBF) and a damage tolerant buckIing restrained braced frame (DTBRBF), are compared with those of equivalent single degree of freedom (ESDOF) systems. Sixty earthquake ground motions recorded in different soil conditions, which are soft rock, soft soil, and near fault, were used to compute the input and hysteretic energy demands in model structures. In case the modal mass coefficient is less than 0.8, the effects of higher modes are considered in the process of converting into ESDOF. According to the analysis results, the hysteretic and input energies obtained from three story and eight story MRF and DTBF agreed well with the results from analysis of equivalent SDOF systems. However in the twenty' story BRBF the results from ESDOF underestimated those obtained from the original structures

• 김진구(성균관대학교 건축공학과 조교수) | Kim, Jin-koo 책임저자
• 최현훈(성균관대학교 건축공학과 박사과정) | Choi, Hyun-hoon