Italian Workshop on 

Shell and Spatial Structures

Topology optimization driven conceptual design of structures 

Nikos D. Lagaros, Stefanos Sotiropoulos, Georgios Kazakis (National Technical University of Athens,Greece)

Over recent years, Topology Optimization is used in order to achieve structures oriented via Architectural Conceptual Design. The basic idea behind Topology Optimization is finding the shape of the final structure which optimizes its structural behavior by distributing material into the design domain, guided by the search for optimal conditions. The presented formulation expands this theory in the field of conceptual design, by the substitution of the material distribution with predefined structural shapes. The form of this structural shapes is independent from the problem formulation; thus, a variety of different structures can derive and satisfy the needs of the conceptual design. In our method instead of using classic topology optimization approaches such as SIMP and regression analysis is performed in order to link the design variables with the objective function of the topology optimization problem. Moreover, static condensation is implemented to reduce the number of degrees of freedom for each predefined shape and assemble the global stiffness matrix of the final structure. The above method is implemented using both 2D triangular elements (plane stress) and 3D shell elements. Furthermore, free form structures are presented making use of 3D shell elements, illustrating innovative architectural structural designs. In this work a novel topology optimization aided structural design methodology is presented, where aesthetic and conceptual design issues are imposed in the topology optimization formulation. The scope of the presented formulation is to provide a general approach for addressing the topic of conceptual design by means of topology optimization and give the opportunity of designing structures that cannot be achieved with ordinary technics.

Acknowledgments

This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH–CREATE–INNOVATE (project code: T1EDK-05603, “HP-OCP: Holistic, High Performance Optimization Computing Platform”).

Nikos D. Lagaros 

Dr. Nikos D. Lagaros is the Dean of the School of Civil Engineering of the National Technical University of Athens (NTUA), Greece and Associate Professor in the Institute of Structural Analysis and Antiseismic Research in the School of Civil Engineering of NTUA. He is the Director of the Personal Computers Laboratory, at the School of Civil Engineering of NTUA. Prior moving to NTUA, he was Assistant Professor in Civil Engineering at the University of Thessaly, Greece. In the past he also served as Visiting Professor at Department of Biological Engineering, Laboratory for Computational Biology & Biophysics, Massachusetts Institute of Technology, Boston, USA and the Department of Mechanical Engineering, Faculty of Engineering, McGill University, Montreal, Canada.

Dr. Lagaros obtained his BEng and PhD, both in Civil Engineering, from NTUA and he teaches classes on Structural Analysis, Optimization and Computer Programming. Dr. LAGAROS has provided consulting, peer-review and expert-witness services to private companies and federal government agencies in Greece and Internationally. A focus of his consulting work is the assessment of buildings after earthquake events and the development of technical software for structural analysis and design. Recently he released the first, real-world, optimum design computing platform for civil structural systems. He also acts as NSF Panellist, for reviewing proposals on seismic performance of masonry, concrete, and other structures, Directorate for Engineering-Civil, Mechanical and Manufacturing Innovation, in Washington DC, since 2010.                                                                   

Dr. Lagaros is an active member of the computational mechanics research community, focusing on (a) nonlinear dynamic analysis of concrete and steel structures under seismic loading, (b) performance-based earthquake engineering, (c) structural design optimization of real-world structures, (d) seismic risk and reliability analysis, (e) soft-computing in structural engineering, (f) fragility evaluation of reinforced concrete and steel structures, (g) inverse problems in structural dynamics, (h) machine learning applications in healthcare, (i) evolutionary computations, (j) structural health monitoring and (k) nano-modelling. Among others, his publication track record includes more than 135 peer reviewed journal paper, 10 books and 25 book chapters while he has presented his work in numerous international venues. His h-index is 35 according to Google Scholar, with more than 4300 citations of his work.