Most structural optimization procedures focus on minimizing the total volume of steel in an attempt to reduce overall costs. However, many other factors can have an effect on the overall cost of a structure. Base column demands in particular, can affect base plate sizes, anchorage, and foundation design. Researchers have found that present methods for estimating column demands are too conservative. Nonlinear time history analyzes were conducted on buckling-restrained braced frames of six heights. Optimized results were found considering three ductility constraints and two optimization objectives. The two optimization objectives were minimized total brace area and minimized base column demands. The results show that designs created by using a minimized column demand objective led to column demands that ranged from 2 to 6% lower than column demands in designs generated by a total brace area minimizing objective. The average brace areas of the designs produced by the total brace area minimizing objective were 25 to 80% less than the designs produced by the column demand minimizing objective. Results showed that large braces in the top stories did not have an effect on column demands in the ground level story. The results indicate that base column demands can be minimized by minimizing braces areas. However, braces areas cannot be minimized by minimizing base column demands.



College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering



Date Submitted


Document Type





BRBF, buckling-restrained braces, column demands, optimization, genetic algorithm