Probabilistic Finite Element Analysis

The finite element method has been used extensively in structural analyses. Traditionally, the properties of the systems which have been modeled using finite elements have been assumed to be deterministic. The uncertainties in the structural response behavior estimates which result from uncertainties in the properties of the system have been accounted for in design using safety and reduction factors. As structures become more complex and industry makes use of materials such as composites, which are known to have random material properties, an alternative approach to design which quantifies the distributions in response may be required. Probabilistic finite element techniques, which are capable of assessing the distributions in response behavior for systems with random material properties, loads and boundary conditions are presented in this thesis. One particular method termed second-moment analysis is examined in detail. This method includes perturbation techniques and is used to compute the expected values and covariance matrices of probabilistic response behavior. Second-moment analyses in conjunction with the finite element method require as input the expected values of the random processes inherent to the system and their covariance matrices. Methods are also presented to compute these parameters for local element averages of the random processes which describe the uncertainty in the system. Implements probabilistic finite element techniques as developed in the study to predict the probabilistic response behavior of marine riser systems in which, certain aspects of the problem are considered probabilistic.