Modifying the span length

If a span length is modified, the result of the operation may depend on the type of span-load definition. And sometimes, special measures must be taken to make the result correct.

The action of modification of span length depends on whether the load on it has been defined "relatively" or "absolutely".

We’ll explain the problem on a simple example.

Let’s have a three-span continuous beam subject to a uniformly distributed load over the top right span.

The length of the loaded span is 5 metres. Let’s move the span’s left node to shorten the span to 3 metres only. The load that is defined in absolute co-ordinates (i.e. it extents from ordinate 0,000 to ordinate 5,000) can’t fit onto the shortened span.

If the load was defined "on span" and "relatively", the result looks like this:

On the other hand, if the load has been defined on "full extent" and "absolutely", the result is different.