Simplified calculation of shear lag effect for high-rise diagrid tube structures

Abstract A high-rise diagrid tube structure is a new type of building structural system that can provide greater lateral stiffness. Simplified calculation methods for diagrid tube structures have been studied by scholars in recent years, but the shear lag effects in such structures have not been reviewed. The shear lag effect will affect the lateral stiffness and stress distribution of a tube structure, so it is necessary to propose a simplified calculation method that can consider the shear lag effect of diagrid tube structures. This paper adopts the principle of stiffness equivalence to equate a high-rise diagrid tube structure to an elastic orthotropic membrane, constructs the stress function considering the shear lag effect under the action of typical horizontal loads, and obtains the stress function through the principle of energy variation. A simplified calculation method is achieved; calculation formulas for the components internal forces and structural displacements are deduced and compared with a detailed finite element program calculation to verify the method. Further, through the simplified calculation method proposed in this paper, two key issues (angle optimization of diagonal columns and evaluation of the shear lag effect at any aspect ratio) are solved in the preliminary design of this kind of structure. Results of this paper can provide a theoretical reference for the preliminary design of a diagrid tube structure. Under the basic condition that only the aspect ratio of the structure is known, the optimal angle of diagonal column can be determined, and the shear lag effect of the diagrid structure can be quickly estimated by the proposed simplified method.