Gusset to Column connection at the End of a Brace Line

[learning2banengineer]

Hi,

When connection the gusset of a concentric brace at the end of a braceline, do we need to connect the gusset for axial load from the horizontal conponent of the brace to the column or is the axial load canceled by the shear from teh deck?

Please refer to attached sketch for clarification.
Thanks.

 

[BAretired]

The diagonal brace force has to be resolved into horizontal and vertical components. The horizontal component goes to the beam while the vertical component goes to the column. Ideally all three members meet at a point, although this may not always be achieved in practice.

The deck is not attached to the diagonal brace and cannot affect the distribution of forces as described above.

BA

 

[ToadJones]

Agree with BA that the simplest way is to break the brace force up into horizontal and vertical components. I have done many connections like this where the brace force was so low that I only connected it to the beam in order to simply fabrication and erection.
See the "Uniform Force Method" pg 13-3 in AISC 360-05 (if you're in the States anyway)

 

[nutte]

That axial force is an internal force in the beam, coming (as you suggest) from the diaphragm. In your scenario, this force does not go through the beam to column connection.

If this braced bay occurred in the middle, and you had another braced bay adjacent to it (or even a few bays down), and the beams between were used to drag the force from bay to bay, then you would need to take this force through the beam to column connection. This is often called a transfer force.

 

[ToadJones]

As nutte suggests, be very aware of your transfer forces. These forces ofen do not show up in computer models unless the model is made properly. I have seen many design drawings and designs for that matter that did not include high transfer forces makign the designs grossly inadequate.

 

[learning2banengineer]

Thank you all for the helpful responses! Yes, I am aware that if the brace is in the middle of a beam line, then there is transfer force going through the column, but if it is at the end, I always feel that even though the horizontal component of the brace load is going into the beam, it would still transfer into the column. But since it is at the end of a beam line, so theoretically there is Zero shear from the diaphragm at that point, any shear from the diphragm would be taken up by the beam and transfer to the brace and cancels out, however, I always feel that if the beam is being push or pulled by the diaphragm, it would still bring the column with it, if we don't need to connnection for any horizontal force at all, does it mean theoretically, we can use a horizontally slotted connection here?