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Chapter 2.2 Simply Supported Beams

Every student of structural engineering is introduced to the most basic, but perhaps most useful of components: the simply supported beam. It starts with a reintroduction of the basic bending, shear and deflections. It is followed by an anecdote by Galileo to shows how easily intuition can fail us; going back to the simply supported solution can lead to safer assumptions of behaviour. Finally some useful approximations are recorded of benefit to the engineer engaged in a more sophisticated analysis.

Figure 2.2.4 Galileo’s Column Storage Problem
‘Gallileo, in his two new sciences, discussed the problem concerning storage of marble columns, which were mounted on blocks to keep them from gathering dirt: A large marble column was laid out so that its two ends rested on a piece of beam; a little later it occurred to the mechanic that, in order to be doubly sure of its not breaking in the middle by its own weight, it would be wise to lay a third support midway; this seemed to all an excellent idea.

It transpired that this was not such an excellent idea. Far from reducing the breakage of stored columns it actually resulted in a number of columns breaking their backs over the central support. The simply supported column had now become a statically indeterminate continuous system. ’

‘There are no units used in the chapters until Chapter 2.5. This is essentially to enable easy comparison of the examples followed.’
‘There are many circumstances where the loading pattern can be approximated without substantial loss.’
Figure 2.2.13 – Point Load Varying Position

Demonstration Spreadsheet

The following figure is available to download in MS Excel format.