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SOME BASIC CONCEPTS FOR SHELL STRUCTURES
By Milo S. Ketchum
 If a picture is worth a 1000 words, then a simple model is worth 1000 calculations.

There are only a few basic structural systems for post and beam structures, but for shell structures, there are thousands, each requiring a unique approach to design.

The supports for a shell are more important than the shell.

Shell structures can usually be understood as a set of beams, arches and catenaries and can be analyzed by that approach.

For any shell structure, there will be a simple method of analysis that can be used to check the more precise analysis.

Stiffest path concepts are useful in understanding shell structures.

Support the edges of shells if they are already supported visually by masonry walls or window walls.

Do not throw away all you structural intuition when you design shell structures.

For ordinary structures, an adequate preliminary design should be within
10 percent Shell structures can be estimated to within 5 percent because the only
usual unknown is the amount of reinforcing.

Shell structures can carry relatively large point loads.

If you rush into computer calculations without a thorough study of the structure with several possible arrangements, then you may not get the best structure.

Shell structures get their strength by shape and not by high strength of materials Do not push stresses to their limit.

In case of doubt, reinforce. Shell structures are very complex and carry forces by many paths.

Shell structures, because of their complexity and unfamiliarity require a large lead time for developing the design.
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