The paper describes two well known but adapted methods for calculating the
probability of failure of structures. First the First Order Reliability Met
hod (FORM) is described using an adapted response surface. Secondly the Dir
ectional Sampling (DS) procedure is described using truncated stochastic di
stributions. Both methods are implemented in the Finite Element Method (FEM
) code DIANA of TNO. The two methods have been applied for calculating the
probability of failure of steel structures. Three examples are presented. (
C) 1999 Elsevier Science Ltd. All rights reserved.