Genetic Algorithm Based Construction-Conscious Minimum Weight Design of Seismic Steel Moment-Resisting Frames

The minimum weight criterion, which has been widely adopted in the literature for optimal design of steel structural systems, is inadequate to fully reflect the initial monetary investment due to lack of consideration of additional construction expenses resulting from varied degree of design complexity such as different member sections and splice/connection types. In this paper, design optimization of seismic steel moment-resisting frames involves simultaneous consideration of two competing objective functions: the steel material weight and an approximate measure of design complexity in terms of the number of different standard steel member section types. The code-compliant seismic structural design follows the equivalent lateral force procedure of the 2000 National Earthquake Hazards Reduction Program seismic provisions in conjunction with American Institute of Steel Construction load resistance factor design seismic steel design criteria. A genetic algorithm is used for the posed biobjective structural optimization problem to produce a set of alternative designs establishing optimized trade-off between the two merit objectives. Numerical examples show that a minimum weight design with a balanced degree of design complexity is expected to achieve an initial investment economy with more accuracy.