Diagrid systems coupled with closed- and open-section shear walls: Optimization of geometrical characteristics in tall buildings

Nowadays diagrid systems are employed worldwide for the realization of tall buildings since they allow to achieve remarkable architectural effects while providing an efficient mechanism to limit lateral displacements. Furthermore, being composed by an assembly of trusses on the exterior of the structure, they are suitable for optimization procedures if changing geometrical parameters, such as the inclination of the external diagonals. Such optimization procedures are generally carried out by means of Finite Element models, focusing mostly on diagrid lateral rigidity. In the last few decades, in order to perform the structural analysis of tall buildings, an analytical formulation, called General Algorithm (GA), was developed by some of the authors, which is much less time-consuming than FE calculations, while allowing to capture important insights on the structural behavior. Moreover, a matrix-based method has been recently proposed for the analysis of diagrid systems, which was shown to be suitable for insertion into the GA and able to provide information on the diagrid lateral and torsional flexibility. In this contribution, we analyze the structural behavior of external diagrid systems coupled with closed-section (CS) and open-section (OS) shear walls using the GA. The analysis was performed by considering lateral forces and torque moments distributed along the height of the building. By the GA, defined the building height and plan geometry, the optimal inclination of the external diagonals was sought, in order to minimize lateral displacements and torsional rotations. The effect of the shear wall type, i.e. CS or OS, was also investigated on the structural response, and it was found to have a significant impact on the torsional rotations.