This paper performs a simultaneous cross-sections and semi-rigid connections optimization for plane steel frames with semi-rigid beam-to-column connections, in company with fixed, semi-rigid and hinged base connections using, for the first time, a bees algorithm (BA), along with a genetic algorithm (GA). Both of algorithms are applied using Shallan et al. [1]optimization model. In this paper, the truthful Kanvinde and Grilli[2]nonlinear model is used for simulating semi-rigid base connections, where this model considers all deformations in different base connection elements under the applied loads to determine the relative spring rotation θ r for the sake of getting accurate base rotational stiffness value. In addition, Frye and Morris [3]nonlinear model is used for simulating semi-rigid beam-to-column connections. The P-∆ effect and geometric nonlinearity are considered. The stress and displacement constraints of AISC-LRFD [4] specifications, alongside size adjustment constraints, are considered in the design process.