An optimization method for steel frames considering the discontinuity of the structural property coefficient in necessary ultimate horizontal resistant force

Horizontal load-carrying capacity of steel rigid-frames is one of the most important mechanical performances required in the practical design. Design horizontal load is lowered by the structural property coefficient Ds, which is determined by the plastic deformation capacity of the frame. A practical method using branch and bound approach for the optimization of steel frame structures considering the discontinuity of structural property coefficient Ds is proposed in this paper, and is verified by three numerical examples. The difference between the solutions under Ai distribution lateral forces and Qun distribution lateral forces is also discussed.