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RISS 인기검색어
- 검색키워드
- 저자 : A. Hedayat (검색결과 2 건)
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Suggesting double-web I-shaped columns for omitting continuity plates in a box-shaped column
Hamed Saffari,Amir A. Hedayat,Nasrin Soltani Goharrizi 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.15 No.6
Generally the required strength and stiffness of an I-shaped beam to the box-shaped columnconnection is achieved if continuity plates are welded to the column flanges from all sides. However,welding the forth edge of a continuity plate to the column flange may not be easily done and is normallyaccompanied by remarkable difficulties. This study was aimed to propose an alternative for box columnswith continuity plates to diminish such problems. For this purpose a double-web I-shaped column wasproposed. In this case the strength and rotational stiffness of the connection was provided by nearing thecolumn webs to each other. Finite element studies on about 120 beam-column connections showed that theoptimum proportion of the distance between two column webs and the width of the column flange(parameter β) was a function of the ratio of the beam flange width to the column flange width (parameter α). Hence, based on the finite element results, an equation was proposed to estimate the optimum value ofparameter β in terms of parameter α to achieve the highest connection performance. Results also showed thatthe strength and ductility of post-Northridge connections of such columns are in average 12.5 % and 54%respectively higher than those of box-shaped columns with ordinary continuity plates. Therefore, adouble-web I-shaped column of optimum arrangement might be a proper replacement for a box column withcontinuity plates when beams are rigidly attached to it.
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Hadi Haeri,V. Sarfarazi,Zheming Zhu,N. Nohekhan Hokmabadi,MR. Moshrefifar,A. Hedayat 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.2
In this paper, shear behavior of non-persistent joint surrounded in concrete and gypsum layers has been investigated using experimental test and numerical simulation. Two types of mixture were prepared for this study. The first type consists of water and gypsum that were mixed with a ratio of water/gypsum of 0.6. The second type of mixture, water, sand and cement were mixed with a ratio of 27%, 33% and 40% by weight. Shear behavior of a non-persistent joint embedded in these specimens is studied. Physical models consisting of two edge concrete layers with dimensions of 160 mm by 130 mm by 60 mm and one internal gypsum layer with the dimension of 16 mm by 13 mm by 6 mm were made. Two horizontal edge joints were embedded in concrete beams and one angled joint was created in gypsum layer. Several analyses with joints with angles of 0°, 30°, and 60° degree were conducted. The central fault places in 3 different positions. Along the edge joints, 1.5 cm vertically far from the edge joint face and 3 cm vertically far from the edge joint face. All samples were tested in compression using a universal loading machine and the shear load was induced because of the specimen geometry. Concurrent with the experiments, the extended finite element method (XFEM) was employed to analyze the fracture processes occurring in a non-persistent joint embedded in concrete and gypsum layers using Abaqus, a finite element software platform. The failure pattern of non-persistent cracks (faults) was found to be affected mostly by the central crack and its configuration and the shear strength was found to be related to the failure pattern. Comparison between experimental and corresponding numerical results showed a great agreement. XFEM was found as a capable tool for investigating the fracturing mechanism of rock specimens with non-persistent joint.
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