Practical second-order inelastic analysis for three-dimensional steel frames subjected to distributed load

A practical second-order inelastic analysis of three-dimensional steel frames subjected to distributed load is developed. This analysis realistically assesses both strength and behavior of a structural system and its component members in a direct manner. To capture second-order effects associated with P - δ and P - Δ, stability functions are used to minimize modeling and solution time. The Column Research Council (CRC) tangent modulus concept is used to account for gradual yielding due to residual stresses. A softening plastic hinge model is used to represent the degradation from elastic to zero stiffness associated with development of a hinge. In proposed analysis, a member has two elements and three nodal points. A plastic hinge location can be captured in analysis as the internal nodal point traces the maximum moment location at each load step. Maximum moments and load-displacements predicted by the proposed analysis compare well with those given by other approaches.