| A general framework for system reliability analysis of frame structures with material and geometric nonlinearities is presented. The structure is subjected to proportionally applied static loads. The material properties, structure geometry, loads, and environmental effects can be random. It is assumed that the structural system fails when one or several global response measures exceed the corresponding specified thresholds, and the first- and second-order reliability methods (FORM and SORM) are employed for the assessment of failure probability.; Analytical expressions for the response gradient of frame structures with elasto-plastic moment-curvature behavior and including the P-{dollar}Delta{dollar} effect are derived for use in reliability analysis. The element resisting forces are expressed explicitly in terms of the nodal displacements and the exact tangent stiffness matrix is derived in order to compute the response gradients analytically. The tangent stiffness matrix is shown to he an asymmetrlc matrix if geometric nonlinearity is included, even when the material is elastic.; A new force method of structural analysis is introduced to compute the reliability of plastic framework. The method is particularly convenient in reliability analysis when the limit-state function is expressed in terms of internal forces. The vector of internal actions is obtained by premultiplying the external force vector by an influence matrix. By simple modification of the influence matrix, one can easily obtain the perturbed internal action vector due to structural variations, such as the formation of a new plastic hinge or the change in a material property.; A general-purpose reliability code, CALREL-NSAP, is developed to perform the reliability analysis formulated in this dissertation. Examples demonstrate the concepts and applications of the proposed methodology. |
