Prediction of shear‐lag effects in framed‐tube structures with internal tube(s)

The shear‐lag phenomenon is a critical consideration in high‐rise building analysis and design. The shear‐lag behaviour of framed‐tube (including tube, tube‐in‐tube and tubes‐in‐tube constructions) is investigated for the behavioural characteristics of the structures and their performance in relation to the various structural parameters. The stiffness factor in terms of the axial stiffness of the columns and the bending stiffness of columns and beams is chosen as a main parameter to explain the shear‐lag phenomenon and the global behaviour of the structures. A simple numerical technique is also proposed for estimating the shear‐lag behaviour of framed‐tube systems with and without multiple internal tubes. Further work is carried out to demonstrate the simplicity and accuracy of the proposed method through the analysis of three framed‐tube structures (of different heights) without internal tubes and three other framed‐tube structures with single, two and three internal tubes. The shear‐lag phenomenon of such structures is studied taking into account the additional bending stresses in the tubes.