This paper describes a stressed-skin diaphragm approach to the optimal design of the internal frame of a cold-formed steel portal framing system, in conjunction with the effect of semi-rigid joints. Both ultimate and serviceability limit states are considered. Wind load combinations are included. The designs are optimized using a real-coded niching genetic algorithm, in which both discrete and continuous decision variables are processed. For a building with two internal frames, it is shown that the material cost of the internal frame can be reduced by as much as 53%, compared with a design that ignores stressed-skin action.
Phan , D. T., Lim, J. B. P., Tanyimboh, T. T., Wrzesien, A., Sha, W., & Lawson, R. M. (2015). Optimal design of cold-formed steel portal frames for stressed-skin action using genetic algorithm. Engineering Structures, 93, 36-49. https://doi.org/10.1016/j.engstruct.2015.02.037