This paper presents various structural system design options for complex-shaped tall buildings—such as twisted, tilted, and freeform tall buildings—and evaluates their comparative structural efficiency. For each complex form category, tall buildings are designed with different contemporary tall building structural systems, e.g., diagrids, braced tubes, and outrigger systems. Comparative structural efficiency between these systems in conjunction with building forms and height is studied. The heights of the studied buildings range from 60 to 100 stories, and the corresponding height-to-width aspect ratios range from 6.5 to 10.8. Parametric structural models are generated with Rhino/Grasshopper to investigate the impacts of various important geometric configurations of complex-shaped tall buildings, such as the rate of twist, angle of tilt, and degree of fluctuation of free form. The parametric models are exported to structural engineering software SAP2000 for analyses and design. Based on the study results, comparative structural efficiency between different structural systems of each complex form category is presented.
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