3 rd American Association for Wind Engineering Workshop Hyannis, Massachusetts, USA August 12 - 14, 2012 * Lead presenter A cohesive performance-based optimization framework for the design of tall buildings subject to wind loads S. Bobby a,* , S.M.J. Spence b , D. Wei c , E. Bernardini d , A. Kareem e Nathaz Modeling Laboratory, University of Notre Dame, Notre Dame, Indiana, USA, a sbobby@nd.edu, b sspence@nd.edu, c lakeat@gmail.com, d ebernard@nd.edu, e kareem@nd.edu ABSTRACT This paper presents the second step in the definition of a tall building design platform for the analysis and optimization of tall buildings within a Performance-Based Design setting. The platform will guide the designer from the initial concept to the final detailed building design through the transition between the following three steps: 1) building sculpting through aerodynamic shape optimization; 2) definition of innovative structural systems using Performance-Based Topology Optimization; and 3) detailed member design within a discrete Performance-Based Design optimization setting. An overview of the platform is given, after which a novel framework for Performance-Based Topology Optimization is described in detail. Finally a number of case studies are presented demonstrating the applicability of the proposed setting. Keywords: Performance-based design optimization, Shape optimization, Wind loads, Tall building design 1. INTRODUCTION An emerging research area for tall building design aims to define novel structural systems tailored specially for modern tall buildings utilizing optimization schemes. Typically, designers have adapted traditional structural systems defined for simple vertical profiles in order to conform to habitability and serviceability requirements as well as stipulations placed by architects and building owners. However, this approach inhibits the systematic exploration of highly innovative structures that may provide more sustainable solutions; thus it is desirable to examine methods for the full design of efficient buildings. The external shape of tall buildings is essential in determining the intensity of the often- governing aerodynamic loads on a structure. Sculpting the geometric profile to reduce the aerodynamic response will ensure the structure meets performance criteria more efficiently (Kareem, 1992; Kijewski et al., 2000). Shape optimization can be used to modify the exterior boundary to attain desired performance levels while meeting designer imposed constraints. While aerodynamic shape optimization of a body immersed in fluid modelled using Computational Fluid Dynamics (CFD) has been attempted before (Kim et al., 2009; Srinath and Mittal, 2010), it has been used primarily in the aerospace industry for optimization of airfoils or parts of aircraft immersed in laminar flow characterized by low Reynolds numbers. To the authors’ knowledge there have been no concrete attempts to implement aerodynamic shape optimization in the field of tall building design. This could be partly due to the bluff nature of the forms and exposure to turbulent flows.