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Optimization of cold-formed steel cross sectional shapes using charged system search (CSS)

Cold-formed steel cross sections have application in a wide range of the engineering structures such as aircrafts, storage vessels and warehouses. As in many thin-walled structures, buckling capacity plays a crucial role in the design of cold-formed steel structural members. Length, material properties and cross-sectional shape are parameters affecting the buckling capacity, with the cross-sectional shape the most influential factor. Recent technological improvements have allowed the fabrication of cold-formed members with nearly any cross sections. This provides an excellent opportunity for the application of formal optimization methodologies towards better stability and ultimately load carrying capacity. We present a Finite Strip Method based on Chebyshev polynomials that allows for fast stability analysis of cold-formed steel members for a variety of boundary conditions. The proposed FSM is then combined with a powerful heuristic optimization engine, Charged System Search (CSS) to explore the shape design space. CSS is inspired by charged particles behavior. It searches the design space by considering candidate answers as charged particles and moving them based on the Coulomb's laws of electrostatics and Newton’s laws of motion to find the global optimum. Manufacturing constraints such as symmetry as well as number and placement of folds are also taken into consideration. The results show the optimal cross-sectional shapes offer 3- to 4-fold increase in the buckling capacity of members.

Author(s):

Babak Ahmadi    
University of Massachusetts Dartmouth
United States

Mazdak Tootkaboni    
University of Massachusetts Dartmouth
United States