NEHRP Clearinghouse

Solution Strategies for Statically Loaded Nonlinear Structures.
Simons, J. W.; Powell, G. H.
National Science Foundation, Washington, DC., November 1982, 112 p.
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This investigation aims at developing a solution strategy which is reliable and substantially automatic for a wide variety of statically loaded nonlinear structures. A framework for nonlinear static solution strategies is developed, based on Newton-Raphson iteration, consisting of four computational tasks: linearization, displacement prediction, state determination, and convergence checking. These tasks are performed in an advancing phase and a correcting phase. Currently available solution strategies are shown to differ in the way particular tasks are performed. The strategies considered include modified Newton methods, Quasi-Newton methods, displacement-controlled iteration, techniques for variable load step selection, and event-to-event strategies. Finally, a general solution strategy is described that includes most existing schemes, plus certain new schemes as options. This strategy permits analysis by either load-controlled or displacement-controlled methods, with flexibility in the choice for the controlling parameters.
ANSR-III computer program; Earthquake engineering; Earthquake resistant structures; Newton-Raphson method; Computer applications; Mathematical models; Algorithms; Nonlinear systems; Stiffness methods; Dynamic structural analysis