Stiffness reduction method for the in-plane design of steel frames

A stiffness reduction method for the in-plane design of steel frames is proposed in this paper. The proposed method is performed by (i) reducing the flexural stiffnesses of the members of a frame on the basis of the first-order forces they withstand and (ii) carrying out Geometrically Nonlinear Analysis. The ultimate capacity of the structure is defined as the point at which the ultimate strength of the most heavily loaded cross-section is reached. Ow-ing to the full consideration of the deleterious influence of the spread of plasticity and imper-fections through stiffness reduction, the proposed approach eliminates the need of using member design equations or modelling member out-of-straightnesses; only cross-section strength checks are required. The verification of the proposed approach against results from the nonlinear finite element modelling of a series of benchmark frames is presented. Copyright ©: SDSS'2016