Uncertainties are a central element in structural analysis and design. But even today they are frequently dealt with in an intuitive or qualitative way only. However, as already suggested 80 years ago, these uncertainties may be quantified by statistical and stochastic procedures. In this contribution it is attempted to shed light on some of the recent advances in the now established field of stochastic structural mechanics and also solicit ideas on possible future developments.

A model elliptic boundary value problem of second order, with stochastic coefficients described by the Karhunen–Loève expansion is addressed. This problem is transformed into an equivalent deterministic one. The perturbation method and the method of successive approximations is analyzed. Rigorous error estimates in the framework of Sobolev spaces are given.

Equations of motion for flexible multibody systems with model uncertainty are developed using the Lagrangian formulation. The dynamic model developed serves to exemplify systems which possess undesirable flexibility by representing it as a stochastic process. Further, a novel methodology for treating uncertainties in flexible systems is proposed. The method uses concepts from stochastic finite elements to address the problem of uncertain parameters in flexible mechanical systems. In particular, the problem of random bending rigidity of a flexible beam is studied. The spatial random process is represented using the Karhunen-Loeve expansion. The response process of the beam, comprising of large rotation and elastic vibration is expressed as a projection on the Homogeneous Chaos. Expressions for the response statistics, including the coupling between the elastic vibration and the large displacements are derived. Comparison of the results obtained with those from Monte-Carlo simulation sho...

In this paper, we first review the impact of the powerful finite element method (FEM) in structural engineering, and then address the shortcomings of FEM as a tool for riskbased decision making and incomplete-data-based failure analysis. To illustrate the main shortcoming of FEM, i.e., the computational results are point estimates based on “deterministic” models with equations containing mean values of material properties and prescribed loadings, we present the FEM solutions of two classical problems as reference benchmarks: (RB-101) The bending of a thin elastic cantilever beam due to a point load at its free end and (RB-301) the bending of a uniformly loaded square, thin, and elastic plate resting on a grillage consisting of 44 columns of ultimate strengths estimated from 5 tests. Using known solutions of those two classical problems in the literature, we first estimate the absolute errors of the results of four commercially available FEM codes (ABAQUS, ANSYS, LSDYNA, and MPAVE) by comparing the known with the FEM results of two specific parameters, namely, (a) the maximum displacement and (b) the peak stress in a coarse-meshed geometry. We then vary the mesh size and element type for each code to obtain grid convergence and to answer two questions on FEM and failure analysis in