Incremental analysis of plane frames with geometric and material nonlinearities

An incremental analysis of nonlinear plane frames is presented. Both geometric and material nonlinearities are considered. The former are allowed for by using suitable stiffness functions and by accounting for the member end-shortening due to bowing. Material nonlinearities are accounted for by inserting infinitesimal rigid-plastic elements between elastic members. The original contribution of the paper is in three directions. Firstly, care is taken to ensure that the size of the algebraic problem to be solved at each step of the incremental analysis is small enough for most of the structures of engineering practice to be efficiently handled even by small computers. Secondly the location of the plastic sections is not fixed a priori but is detected during the analysis. Finally, some important results available in literature,1 are discussed within the framework of the present formulation