SMRF Bracing Requirements

[JAE]

Say you have a Special Moment Resisting frame in accordance with the latest AISC Specification. In that spec there is a requirement that reduced beam section connections have lateral bracing on the beam such that the plastic moment can be realized.

This bracing must have a required stiffness and a required strength per the AISC spec.

The question is, if you have a moment frame with no concrete deck, (a wood framed building using a steel moment frame) and you use perpendicular steel wide flanges, connected to your moment frame as connections...will rotational restraint alone be acceptable?

We can insert a perpendicular WF beam and connect it to the flanges of the moment frame beam - to resist rotation, but can't necessarily resist lateral translation with that beam.

Any thoughts on that? The AISC Chapter C spec on bracing (in which the seismic spec refers to) says rotational restraint is acceptable.

 

[JAE]

bump

 

[Ron]

JAE...since you are using W sections for the beams and columns, why not "box gusset" the beam-to-column connection? Wouldn't that achieve the objective?