A Numerical Method for the Determination of the Moment-Rotation-Capacity of Thin Walled Members

Summary

For the application of elastic-plastic design of steel frames the rotational capacity of the plastic hinges is of great importance. This rotational capacity is limited by local buckling of the beam in the plastic zone. The sensivity of buckling is mainly governed by the relation of width/ thickness of the thin walled parts of the profile. The behaviour in a plastic hinge is determined by the moment- rotation- behaviour in the post buckling range. A calculation model is presented which reduces the problem of local buckling in the plastic range with the help of a static condensation. The three- dimensional structure is transformed into a linear beam structure with additionally defined degrees of freedom for local buckling effects.