Reanalysis of trusses using modified initial designs

This paper presents a solution procedure for reanalysis using a mixed exact -approximate approach. The procedure, which is based on the reduced basis m ethod, uses an efficient exact reanalysis method to handle a limited number of dominant member area and topological changes. A modified initial design (MID), associated with which is a recalculated inverse of the modified sti ffness matrix, is the starting point for the approximate technique. Local g eometrical changes may be accounted for within the modified initial design. An approximate technique is then used to handle the rest of the changes. T his solution procedure significantly improves the accuracy of the approxima tion and conveniently accommodates geometrical and topological changes whic h occur in layout optimization of structures. The main purpose of this pape r is to exploit, for a better balance between efficiency and accuracy, the advantages of the exact approach for reanalysis which is efficient for a sm all number of changes and the approximate approach for reanalysis which is efficient for a large number of changes of small magnitude.