An Efficient Stiffness Demand‐Based Section Optimization Strategy for Aseismic Super High‐Rise Frame Core‐Tube Structures Using General Flexure‐Shear Coupling Model

ABSTRACT To maximize design efficiency and economy of stiffness‐sensitive super high‐rise buildings having numerous structural components of various types and significantly diverse configurations along height, it is beneficial to establish an explicitly direct transfer of lateral stiffness demand control from structure to component levels in determining cross section. The key aspect of such transfer lies in the development of the dynamical equivalence between a generalized flexure‐shear coupling model (FSM) and a finite element model (FEM). Such equivalent link is attained by calibrating the shear‐to‐flexure stiffness ratio of the uniform FSM (FSM‐U) using the first two vibration periods of a finite element model (FEM). Based on this, the gradients related to modal inter‐story drift (ISD) and the maximum ISD with respect to cross section can be analytically reached, with the frequency versus cross section characteristic equation and the SRSS combination rule, and incorporated into the sequential quadratic programming (SQP) optimization algorithm. The formulation of the optimization problem comprehensively addresses the constraints from stiffness, ductility, internal force distribution, and geometry of typical super high‐rise frame core‐tube structures. The efficiency and convergence performance of the proposed novel elastic section optimization strategy are fully demonstrated via a case study of a 40‐story frame core‐tube structure. The analytical gradients from FSM‐U clearly reflect the internal adjustment mechanism between the objective and constraints. The design rationality is maintained even with a significant reduction of 29.5% in the objective of material amount compared to the initial structural model. Additionally, different constraints demonstrate varying degrees of sensitivity to the optimization process.