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The design of the best structure for a given purpose
depends upon the criterion used for optimisation. Structures
may be designed to safely transmit a given system of forces using
the least weight of material.. They may also be designed to have
maximum stiffness of a certain type for a given weight or
alternatively to have the greatest possible fundamental
frequency of vibration. These problems, although in general
distinct from one another, are closely related and much can be
achieved towards maximisation of stiffness and frequency by the
use of minimum weight designs. In fact it can be shown that a
minimum weight framework is the stiffest structure of that weight
for the force system, which it is designed to carry.x
The present report is concerned exclusively with the problem of
the design of structures of minimum weight, which are required
to transmit specified forces. Some attention will be given to
frameworks because, in particular, methods of approximate
numerical analysis are more readily formulated for this type of
structure, but the main emphasis will be placed upon the design
of structures formed from plates of variable thickness reinforced
by direct load carrying members.
See para,l.4 |
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