Reverse the orientation of structural framing elements.
Note: The Flip Structural Framing End tool is available only to students and to Autodesk Maintenance and Desktop Subscription customers for the Revit 2015 R2 release of the software.
When you place framing elements, their start/end orientation is determined by drawing order. The first click is the start; the second click is the end. You need to understand the beginning and end of framing elements when setting up connections, fixity, and other workflows such as tags.
Non symmetrical elements can show how this orientation is important while modeling. Consider the following pre-cast beam with a single cut end. 
When sketched between a column and a supporting pre-cast I beam in a plan view, the placement initially appears correct. Note the analytical model has been exposed to show the start (green) and end (red). 
When viewed in an elevation, this is not the case. 
To adjust this, use the Flip Structural Framing End tool. Select the beam, right click the element, and select Flip Structural Framing Ends.
The beam will flip its orientation. Geometry attributes for start and end parameters swap in order to preserve the element position. Use the shape handles of the element to make any necessary finite geometry adjustments. 