Probabilistic FEM for reliability of strain softening media

Feasibility of applying probabilistic FEM for random strain-softening media is explored. Based upon the incremental theory, a modified initial stress method is introduced associated with displacement control technique to deal with the strain-softening problem. A probabilistic finite-element formulation for strain-softening media is proposed based on the direct differentiation scheme on the suggested modified initial stress method. Adjoint vector method is applied to save the computational time for the problem involving large amount of random variables. An efficient reliability evaluation is then performed by the proposed probabilistic FEM, and displacement Taylor expansion scheme is suggested to avoid re-factorization of global stiffness matrix during the iterative computation of design point. A numerical example is given to demonstrate the proposed method. (C) 2001 Elsevier Science B.V. All rights reserved.