Deformation of Circular and Elliptical T-Tubular Joint Chords Under Different Loading Modes

Yousif A. Khalid, Barkawi B. Sahari, Megat M. Hamdan and Abdalla F. Hamed

T-tubular joints of elliptical and circular cross-sections tubes for the main tube(chord) weided to circular cross-section tubes for the branches (braces) have been tested experimentally. Three cases, of joint connections, namely Case 1, Case 2, and Case 3 were selected. For Case 1, the brace is perpendicular to the circular chord outer diameter, while in Case 2 the brace was perpendicular to elliptical chord minor diameter and for Case 3 the brace was perpendicular to the elliptical chord major diameter. The chord was held as fixed condition for all cases. The material used for all tubes was mild steel. Four basic loading modes of tension, compression in plane bending and out of plane bending, were implemented. Load-displacement and momentangle relations were obtained from each case and under each loading mode. For axial tension and compression loading modes, Case 3 shows an 17.0 and 12.0% improvement respectively in the ultimate load when compared to Case 1 while 24.0 and 27.3% increase in the ultimate moment were found in-plane and out-of-plane bending load modes respectively. On the other and 21.1, 27.7, 1 and 7.5% in the ultimate load and moment for tension, compression, in-plane bending and out of plane bending loading modes respectively was found when Case 2 compared to Case 1. Comparison of circular chord tubular joints test results and their empirical equations shows a good agreement. In general Case 3 shows a significant improvement in the static stregth for all loading modes when compared to Case 1, while a great benefit was observed for the in-plane bending loading mode.

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