링크의 초과강도 예측에 의한 편심가새골조의 역량설계
Capacity Design of Eccentrically Braced Frames through Prediction of Link Overstrength
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초록
편심가새골조(EBF)의 역량설계법에 의하면, 링크가 완전항복 및 변형경화 상태일 때 기둥, 링크외부보, 가새(비소산 부재)는 탄성거동해야 한다. 현행 AISC 341은 역량설계에 필요한 변형도경화계수(SHF)를 1.25로 제시하고 있으나, 실제로 건물이 고층 규모일수록 모든 링크가 이처럼 동등한 수준의 초과강도에 도달할 가능성은 매우 낮아진다. 본 연구에서는 링크의 SHF를 정밀하게 예측하는방법을 제안함으로써, 역량설계법의 목적을 달성하면서 구조물량을 절감하고자 하였다. 제안한 방법의 효과를 검증하기 위해 선형해석을 2회 수행하여 SHF를 예측하고, 이를 비선형 해석결과와 비교하였다. 다음으로 비선형 해석에 의한 응답을 분석하여 구조물의 한계상태에서 비소산 부재들의 항복 여부를 확인하였다. 그 결과, 본 연구의 방법으로 설계된 구조물은 링크의 SHF를 정확히 예측함으로 인해 물량이 큰 폭으로 절감되었으며, 비소산 부재들도 모두 탄성상태를 만족하는 것으로 나타났다.
Abstract
According to the capacity design of eccentrically braced frames (EBFs), non-dissipative members such as columns, link-exterior beams, andbraces must remain within the elastic region when a fully-yielded and strain-hardened link transmits force to them. The current AISC 341standard suggests a strain-hardening factor (SHF) of 1.25 for a link under capacity design, regardless of its properties. However, all the links in anEBF are not likely to yield simultaneously to the extent to which the overstrength corresponding to 1.25 times their expected strength is attained,especially for high-rise buildings. Considering this phenomenon, a technique to predict the SHF of links at the limit state of the structure isproposed in this paper. The exact prediction of the links’ SHF could save structural quantities dramatically while achieving the principle ofcapacity design. To validate the effectiveness of this technique, SHF values predicted by conducting linear analysis were compared with thoseevaluated by nonlinear analysis. Furthermore, the maximum demand-to-capacity ratios of the non-dissipative members were calculated to verifywhether they would remain elastic at the limit state of the structure. Consequently, EBFs designed by the proposed method showed substantiallyeconomical quantities through the exact prediction of the SHFs, and the intention of capacity design was successfully achieved.
참고문헌 (13)
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