Stiffened composite hypar shell roofs under free vibration: Behaviour and optimization aids

A perusal of the literature brings out the fact that research reports on the vibration characteristics of stiffened composite hypar shells are missing. The present paper combines an eight noded shell element with a three noded beam element to develop a finite element tool for solution of such problems. Benchmark problems are solved to validate the approach and free vibration response of stiffened composite hypar shells is studied both with respect to fundamental frequency and mode shapes by varying the number and depth of stiffeners, laminations and boundary conditions. The results are further analysed to suggest guidelines to select optimum stiffened shell configurations considering the different practical constraints.