ABSTRACT
ABSTRACT: The cellular shell consists of two circular cylindrical shells and a longitudinal stiffening welded between them. Halved Circular Hollow Section (CHS) stiffeners are used to ease the welding of outer shell elements. Advantages of cellular shells are as follows: thinner structural parts can be used, which decreases the welding cost, large bending and torsional stiffness can be achieved with small diameter. In the present study a simple supported tubular beam is strengthened in the middle part of the span by cellular shell, which enables to fulfil the strict deflection constraint and the limiting of the shell diameter. The single tube version has too large thickness unsuitable for fabrication and the structural volume is larger than the cellular shell one. The shell thicknesses, dimensions of stiffeners and the length of the stiffening are optimized for minimum cost. The cost function is the cost of material, welding and painting.
