• Earthquakes and Structures
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• 제21권5호
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• pp.551-562
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• 2021

In this study, the generalized intensity measure (IM) named I_Npg is analyzed. The recently proposed proxy of the spectral shape named N_pg is the base of this intensity measure, which is similar to the traditional N_p based on the spectral shape in terms of pseudo-acceleration; however, in this case the new generalized intensity measure can be defined through other types of spectral shapes such as those obtained with velocity, displacement, input energy, inelastic parameters and so on. It is shown that this IM is able to increase the efficiency in the prediction of nonlinear behavior of structures subjected to earthquake ground motions. For this work, the efficiency of two particular cases (based on acceleration and velocity) of the generalized I_Npg to predict the peak floor acceleration demands on steel frames under 30 earthquake ground motions with respect to the traditional spectral acceleration at first mode of vibration Sa(T₁) is compared. Additionally, a 3D reinforced concrete building and an irregular steel frame is used as a basis for comparison. It is concluded that the use of velocity and acceleration spectral shape increase the efficiency to predict peak floor accelerations in comparison with the traditional and most used around the world spectral acceleration at first mode of vibration.

• Structural Engineering and Mechanics
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• 제90권3호
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• pp.313-323
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• 2024

Most of existing buildings in Mexico City are made of reinforced concrete (RC), however, it has been shown that they are very susceptible to narrow-band long duration ground motions. In recent years, the use of dual systems composed by Buckling Restrained Braces (BRB) has increased due to its high energy dissipation capacity under reversible cyclical loads. Therefore, in this work the behavior of RC buildings with BRB is studied in order to know their performance, specifically, the energy distribution through height and response transformation factors between the RC and simplified systems are estimated. For this propose, seven RC buildings with different heights were designed according to the Mexico City Seismic Design Provisions (MCSDP), in addition, equivalent single degree of freedom (SDOF) systems were obtained. Incremental dynamic analyses on the buildings under 30 narrow-band ground motions in order to compute the relationship between normalized hysteretic energy, maximum inter-story drift and roof displacement demands were performed. The results shown that the entire structural frames participate in energy dissipation and their distribution is independent of the global ductility. The results let propose energy distribution equations through height. Finally, response transformation factors between the SDOF and multi degree of freedom (MDOF) systems were developed aimed to propose a new energy-based approach of BRB reinforced concrete buildings.

• 한국지반공학회논문집
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• 제37권6호
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• pp.29-37
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• 2021

화강 풍화대 지반은 지반구조물의 주요 지지층으로 활용되고 있으므로 화강 풍화대의 지반특성을 평가하는 것은 중요하다. 특히, 내진설계의 중요성이 부각되고 있음에 따라 지반분류 및 지반 최대 전단 탄성계수(G_max) 평가에 활용되는 전단파 속도(V_S)의 합리적인 평가의 중요성이 증가하고 있다. 본 연구에서는 국내 화강 풍화대 지층을 대상으로 표준관입시험(SPT: Standard penetration test) N₆₀ 및 채취한 시료의 화학적 풍화지수를 바탕으로 비선형 다변량 회귀분석을 수행하여 전단파 속도(V_S) 추정식을 제안하였고, 기존 관련 연구결과와 비교하였다. 화학적 풍화지수를 추가적인 독립변수로 고려하여 풍화도를 고려한 경우 N₆₀만을 사용하여 수행한 단순 회귀분석 결과에 비해 결정계수가 증가하여 전단파 속도 추정식의 정확도가 향상됨을 확인하였다.