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TSD 접합부의 강성을 고려한 5층 철골골조구조물의 비탄성 시간이력해석
강석봉,이재환,Kang, Suk-Bong,Lee, Jae-Hwan 한국강구조학회 2010 韓國鋼構造學會 論文集 Vol.22 No.3
본 연구에서는 횡력을 받는 구조물 거동에 대한 보-기둥 접합부의 영향을 확인하기 위하여 5층 철골구조물을 KBC2005 건축구조 설계기준에 맞게 구조설계 하였으며 접합부를 완전 강접합부로 이상화한 경우와 반강접 접합부로 설계하였다. 철골 보 및 기둥의 모멘트-곡률관계는 화이버모델을 이용하여 확인하였으며 반강접 접합부의 모멘트-회전각 관계는 파워모델 그리고 철골 보, 기둥 및 접합부의 이력거동은 3-매개변수 모델을 이용하여 나타내었다. 5층 철골구조물은 개별골조와 연결골조의 2차원 구조물로 이상화하였다. 4개 지진파의 재현주기 수준별로 산정한 최대지반가속도와 푸쉬오버해석의 최대밑면전단력을 위한 지반가속도에 대하여 시간이력해석을 실시하여 지붕층 변위, 밑면전단력, 층간변위, 접합부 요구연성도, 기둥, 보 및 접합부의 최대모멘트 그리고 소성힌지 분포 등을 확인하였다. 반강접 접합부 골조는 완전 강접합 골조에 비해 적은 밑면전단력이 발생하였으며 기둥, 보 및 접합부에 발생하는 휨모멘트의 크기와 증가율도 적었다. TSD 접합부는 우리나라 설계수준의 지진하중에 대하여 예제 구조물에서 경제성과 안전성을 확보 할 수 있음을 확인할 수 있었다. In this study, a five-story steel frame was designed in accordance with KBC2005 to evaluate the effects of the beam-column connection on the structural behavior. The connections were designed as fully rigid and semi-rigid. The fiber model was used to describe the moment-curvature relationship of the steel beam and the column, the power model for the moment-rotation angle of the semi-rigid connection and the three-parameter model for the hysteretic behavior of the steel beam, column, and connection. The structure was idealized as separate 2-D frames and as connected 2-D frames. The peak ground accelerations of four earthquake records were modified in a time-history analysis for the levels of the mean return period and for the maximum base-shear force in a pushover analysis. The top story displacement, base-shear force, story drift, demanded ductility ratio for the semi-rigid connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were examined in the time-history analysis. The frame with the semi-rigid connection yielded a lower base-shear force, less magnitude, and increasing ratio in the bending moment of the column, beam, and connection than the frame with a fully rigid connection. The TSD connection was deemed to have secured the economy and safety of the sample structure that was subjected to seismic excitation for the Korean design level.
온간 ECAP 법에 의해 제조된 5083 Al 합금의 미세조직과 기계적 특성
강석봉,강효경,김향욱,Bachelard, L . 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.5
The microstructure and mechanical properties have been investigated on a commercial 5083 aluminum alloy processed by the equal-channel angular pressing (ECAP) at 473K. The microstructure of a single pass sample consisted of elongated subgrains. Increasing the number of pass led to very fine equilibrium grains having high angle grain boundaries. The 0.2% yield stress and hardness after a single pass increased greatly, and then kept constant with additional straining. On the other hand, the elongation to failure of a single pass sample decreased a little to compare with sample before ECAP, but there was no further reduction with additional straining. Recrystallization partially occurred in ECAPed 5083 aluminum alloy when annealed at 523K for 1 hr, and completely finished when annealed only at 573K for 1 hr. With increasing the number of pass, the onset temperature of recrystallization decreased and the rate of softening increased.
강석봉,김형욱,이수태 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.2
Aging behavior of Al-Mg-Si alloys with high silicon content was investigated in the present study. Excess silicon leads to unique aging behavior. The Al-Mg-Si alloys show seven exothermic peaks in DSC thermogram. These peaks seem to be induced by the formation of clustering of Si and Mg atoms, G-P zone, unknown small precipitates, β$quot; phase, B' phase, Si particle and β phase. The content of excess Si has no relationship with the precipitation of β$quot; phase and B' phase, but it affected on the formation of Si particles. Natural aging has a distinct influence on the subsequent precipitation process. It is proposed that the formation of stable silicon clusters during natural aging is the major reason for such an effect.