ELASTOPLASTIC ANALYSIS OF SEMIRIGID FRAMES UNDER CYCLIC LOADING

The elastoplastic analysis of semi-rigidly connected steel frames unde r cyclic loading conditions is performed using a general matrix mathem atical programming approach. The finite incremental formulation used f or a suitably discretized structure is briefly developed from the thre e governing relations of equilibrium, compatibility, and constitutive law. Under the assumptions of yielding through generalized plastic hin ges that obey piecewise linear yield criteria, small geometry, and qua sistatic loading, the analysis for a specified load increment becomes the familiar linear complementarity problem of mathematical programmin g. The computational scheme used for capturing exactly all hinge activ ations and unloadings for a cyclic loading program is described. Numer ical examples are given to illustrate application of the approach.