Elasto‐plastic large deformation analysis of space‐frames: A plastic‐hinge and stress‐based explicit derivation of tangent stiffnesses

This paper deals with elasto‐plastic large deformation analysis of space‐frames. It is based on a complementary energy approach. A methodology is presented wherein: (i) each member of the frame, modelled as an initially straight space‐beam, is sought to be represented by a single finite element, (ii) each member can undergo arbitrarily large rigid rotations, but only moderately large relative rotations; (iii) a plastic‐hinge method, with arbitrary locations of the hinges along the beam, is used to account for plasticity, (iv) the non‐linear bendin–stretching coupling is accounted for in each member, (v) the applied loading may be non‐conservative and (vi) an explicit expression for the tangent stiffness matrix of each element is given under conditions (i) to (v). Several examples, with both quasi‐static and dynamic loading, are given to illustrate the accuracy and efficiency of the approaches presented.