Diagrid system coupled with shear walls: Analytical investigation on the dynamical response in tall buildings

Diagrids are tubular structural systems made up of mega-diagonals arranged in a triangular or tetrahedral pattern, which are placed all over the external surface of the building and usually span across several floors. In the last two decades, diagrids have experienced a remarkable development as efficient structural systems in tall building design and construction. This was mainly due to their high lateral stiffness, capability to realize complex-shaped structures and obtain impressive aesthetic results, flexibility of the external diagonals' layout, etc. The structural analysis of these systems is usually carried out by the Finite Element Method (FEM) or by numerical calculations based on simplified assumptions. Recently, we developed a matrix-based method (MBM) to perform the structural analysis of diagrid systems under static forces. The MBM was then coupled with an analytical formulation developed in the past years by some of the authors, the so-called General Algorithm (GA), in order to study the structural response of an external diagrid tube coupled with an internal shear wall under lateral and torque static actions. The study allowed to investigate the influence of the diagonal inclination on the lateral and torsional flexibility of the diagrid-core system. In the past years, the analytical formulation of the GA was also made suitable to analyze the response of three-dimensional tall building in the dynamic regime. In this contribution, we show new results regarding the dynamical behavior of an external diagrid structural system coupled with an internal shear wall, as obtained from the GA calculations. Modal analysis was carried out in order to obtain the natural frequencies and mode shapes of the tall building, and the influence of the diagonal inclination on the results was also investigated. Moreover, by applying different harmonic oscillations at different frequencies at the base of the building, the damped dynamical response of the different diagrid-core systems was investigated.