FREE-VIBRATION ANALYSIS AND SHAPE OPTIMIZATION OF VARIABLE THICKNESS PLATES, PRISMATIC FOLDED PLATES AND CURVED SHELLS .1. FINITE STRIP FORMULATION

This paper deals with the free vibration analysis of prismatic folded plate and shell structures supported on diaphragms at two opposite edges with the other two edges arbitrarily restrained. The analysis is carried out by using curved, variable thickness finite strips based on Mindlin-Reissner shell theory, which allows for transverse shear deformation and rotatory inertia effects. The accuracy and relative performance of a family of C(0) strips are examined. Results are presented for a series of problems including plates, cylindrical shells and box girders. In a companion paper, these accurate and inexpensive finite strips are used for structural shape optimization.