Optimization of Tall Buildings Using Diagrids

Elena Mele
Professor
University of Naples Urban Ferderico II, Naples

Diagrid structures for tall buildings have recently emerged as a new solution that merges structural efficiency, decorative qualities and morphological versatility. This presentation proposes a design strategy based on sizing optimization techniques, as either an alternative to, or a refinement of, the preliminary sizing methods suggested in literature for regular diagrids. In addition, the approach provided here can also be used for complex and non-conventional patterns, as opposed to the existing procedures that mainly deal with regular geometries. Different geometrical patterns (regular, variable angle, variable density) for diagrid structures are explored, together with a fully non-uniform diagrid-like pattern, which mimics the principal stress trajectories on the building fa├žade.

Strategies for the generation, preliminary design and structural optimization are proposed for the different patterns; in particular, the optimization process is treated with mono-objective genetic algorithms, by minimizing the structural weight and imposing a constraint condition on the lateral stiffness of the building. Thorough comparisons, both among the patterns, and between the outcomes of the preliminary design procedures and the optimization processes, are carried out. The comparisons are administered in terms of structural weight, diagonal cross-section distribution along elevation, deformed configuration, lateral displacements, inter-story drift ratio, and diagonal strength demand-to-capacity ratio. Additional parameters are introduced in order to compare the constructability of the different diagrid-like solutions. Finally, the structural and cost efficiency of the different patterns is presented. and design implications are discussed.