February 19, 2015

How can I run a continuous beam over a column in RISAFloor?

There are many framing designs that involve running a continuous beam over the top of a column. You have always been able to model this situation in RISAFloor, however the program traditionally considered the connection to be Fixed, thereby putting bending moment into the column. The connection detail for such a situation is often a simple connection that is unable to transfer moment. This allows the beam to pivot over the top of the column.


In the example below, the columns all have fixed tops (default). This can be visually confirmed by the fact that the bending moment on the left side of the column does not match that on the right side of the column:

Column Top Pinned 01

In the columns spreadsheet the Top Fixity of that column can be changed to pinned:

Column Top Pinned 02


After solving again the moment on either side of the column is nearly the same. The reason it is not identical is because the moment is reported at the face of column, but there is a moment gradient through the depth of the column.

Column Top Pinned 03



When transferring the model into RISA-3D it can also be visually verified that a pinned end release exists at the top of this column:

Column Top Pinned 04

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This entry was posted by RISA News on Thursday, February 19th, 2015 at 9:27 am and is filed under Technical Solutions. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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