Automatic design of space steel frame using practical nonlinear analysis

An automatic design method of steel frames using practical nonlinear analysis is developed. The geometric nonlinearity is considered by the use of stability functions. The transverse shear deformation effect in a beam–column is accounted for. A direct search method is used as an automatic design technique. The unit value of each member is evaluated by using LRFD interaction equation. The member with the largest unit value is replaced one by one with an adjacent larger member selected in the database. The weight of the steel frame is taken as an objective function. Load-carrying capacities, deflections, interstory drifts, and ductility requirement are used as constraint functions. Case studies of the planar portal frame and the space two-story frame are carried out.