Large scale reliability-based design optimization of wind excited tall buildings

Recent trends in the design and analysis of large scale wind excited structures, such as tall buildings, are towards performance-based design strategies. This is partly due to the success of these types of frameworks in such fields as seismic engineering and partly due to the ever growing computational power at the disposal of engineers. While there is tremendous interest in developing appropriate tools for wind engineering, a simple transfer of methods from seismic engineering is not possible due to the inherently complex nature of the exciting mechanism. The successive performance-based optimization of the structural system is a further leap forward that should be tackled simultaneously if problems of practical interest, often characterized by thousands of performance constraints, are to be solved. In this paper a component-wise performance-based design framework is proposed, based on the concept of a directional fragility model that rigorously combines the directional building aerodynamics and climatological information. An efficient reliability-based design optimization scheme is then proposed, based on decoupling the traditionally nested optimization loop from the reliability analysis carried out through the proposed performance-based design framework. The decoupled optimization problem is solved by defining a series of approximate explicit sub-problems in terms of the second order response statistics of the constrained functions.

► A structural reliability framework is defined for wind-excited structures.
► The concept of iso-fragility surfaces is introduced.
► A decoupling approach to reliability optimization of tall buildings is presented.
► The extreme efficiency of the proposed framework is clearly demonstrated.
► The central role played by fragility during optimization of tall buildings is shown.