The constitutive model with a single damage parameter describing creep-damage behaviour of metals with respect to the different sensitivity of the damage process due to tension and compression is incorporated into the ANSYS ®nite element code by modifying the user de®ned creep material subroutine. The procedure is veri®ed by comparison with solutions for beams and rectangular plates in bending based on the Ritz method. Various numerical tests show the sensitivity of long-term predictions to the mesh sizes and element types available for the creep analysis of thinwalled structures. IntroductionEngineering structures operating at elevated temperatures such as fossil power plants, chemical plants, reactors, etc. are designed with respect to increased requirements of safety and assurance of long-term reliability. One of the main factors which must be considered in the long-term structural analysis is time-dependent material behaviour coupled with damage evolution (Roche et al., 1992). A powerful tool for the lifetime prediction is the continuum damage mechanics approach which is based on the formulation of constitutive and evolution equations for inelastic strains and material damage. Incorporating these material models into the ®nite element code predictions of time-dependent stress, strain and damage ®elds can be performed by numerical solution of nonlinear initialboundary value problems (e.g. . The ®rst problem arising by creep damage analysis is the formulation of a phenomenological material model that is able to describe the sensitivity of creep strain and damage rate to the stress level, stress state, temperature level, environmental effects, etc. Such a model must be able to extrapolate the experimental creep data usually available from uniaxial short-term creep tests and realised for narrow stress ranges to the in-service loading conditions in the real structure. The second problem can be related to the quality of the ®nite element predictions particularly by analysis of structures with complex shapes.The structural analysis of thinwalled components (pressure vessels, pipes, pipe bends, etc.) can be performed using the mechanical models of plane stress (strain) states or equations of shell theory. In the case of plane stress (strain) problems numerous ®nite element simulations considering creep damage effects has been made because of experimental data available for veri®ca-tion. Examples are discussed by Saanouni et al. Since these examples con®rm the ability of ®nite element simulations to predict stress redistributions and failure times with accuracy enough for engineering applications and can be used as benchmark tests by development of user de®ned material subroutines incorporating damage evolution a little effort has been made for the analysis of transversely loaded thinwalled structures. Numerical results for rupture times of rectangular plates in bending are given by Bodnar and Chrzanowski (1994), Bialkiewicz and Mika (1995) based on in-house ®nite element codes and Altenbach and Naumenko (1997) for re...