<a name="programs">PROGRAMS FOR SHELL ANALYSIS</a>

For shells with double curvature, like hypars and domes, one must use Dr. Clough’s Universal Solver, namely, the Finite Element Method. Use of this method requires experience, and the cost for the program if it is not available, can be high, not including the time for learning to use the program. These costs may be beyond the budget for a small firm. In any case the designer should be aware of the methods for approximate analysis.

With folded plates and barrel shells, it is a different matter. The F. E. M. seems to me to be very cumbersome for making a thorough study with all the possible structural combinations. These structures have many elements necessitating large and cumbersome models, not reflecting all the dimensional possibilities. I have developed an analysis program for folded plates, and another one for barrel shells based on the same folded plate method.

The folded plate program has some unique features. (1) It is possible to analyze systems in which the plates elements vary in depth. This is usually the case, and the bending moments in the slab will be changed greatly from slabs that do not have a variable depth. The same is true, of course, for any structural slab. (2) It is possible to analyze ribbed or waffle slabs. (3) The structure can be analyzed for geometric nonlinear affects by correction, successively, of deflections after each pass, until the change in deflections is small.

The barrel shell program is also capable of the above, and shells of any configuration and support conditions can be analyzed. These programs are not finite element programs and give stresses only at the center of the span for longitudinal and slab bending moment and at the support for shear stresses. The designer must have the necessary knowledge, structural intuition, and imagination to design the entire structure. It is not recommended for structures over, say, 100 feet span.


I have prepared an example to show the analysis of a typical shell. It is a single barrel with an edge beam and there is symmetry at the valleys so the analysis for two barrels.

To see this example, click HERE


You can download them by clicking HERE

You will need to unzip them which requires a program such as Winzip which can be downloaded from the Internet.

These programs are written in GWBASIC but will run on Qbasic, Quickbasic, or Power Basic. Some of you may not be familiar with the use of this language. Also they use feet, inches and pounds as units.

Qbasic is available on the Windows 95 CD ROM together with Help menues.

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