Bracing/Moment Frames at HSS to Glulam interface

[WiSEiwish]

I have an upcoming project that is going to be utilizing curved glulam beams supported by HSS columns. The building will be in a high seismic area (SDC >=D). I'm trying to figure out possibilities for providing lateral stability to the structure. Do braced frames in seismic regions require a beam-column connection or can the gussets be solely connected to the columns? I can't have a moment frame due to the wood-steel connection. An option may be to use shear walls outside of the column line, but I'm not sure that would be ok with the architect.

Any thoughts?

 

[hokie66]

Maybe it is terminology, but beam-column connections are required regardless of whether it is a seismic region.

 

[BAretired]

PE2012 wrote and BA responded:
I have an upcoming project that is going to be utilizing curved glulam beams supported by HSS columns. The building will be in a high seismic area (SDC >=D). I'm trying to figure out possibilities for providing lateral stability to the structure. Do braced frames in seismic regions require a beam-column connection (see hokie's comment) or can the gussets be solely connected to the columns? (what does this mean?)I can't have a moment frame due to the wood-steel connection. (I'm not sure that you can't, although it may be an awkward detail.) An option may be to use shear walls outside of the column line, but I'm not sure that would be ok with the architect. (That would be structurally okay.)


BA

 

[jittles]

I think PE2012 needs to clarify. Maybe he meant was "Do braced frames in seismic regions require that the brace be connected to both the beam and column or is a connection of the gusset to just the column OK?" Of course you have to have the beam connect to the column...

With a steep brace angle it is entirely possible to end up with a concentric brace connection that only attaches to the column. Everything else is tracking loads and checking all the pieces.

Not sure about code provisions for wood beam/steel column/steel brace frame system. It seems like you could justify it somehow.

 

[wannabeSE]

I do not know how a wood and steel braced frame can be reconciled with the seismic requirements in ASCE 7. However, it is possible to detail an all steel braced frame with the beam connected to the gusset plate. A example is in the Steel Tips on Seismic Detailing of Gusset Plates for Special Concentric Braced Frames (

http://www.steeltips.org/steeltips/tip_details.php?id=96).

The connection is similar to what is shown here:

https://nees.org/data/get/NEES-2008...CBF-Instrumentation_20090720_INST_Page_1.png.

Also, the 2nd edition of AISC's Seismic Design Manual show a similar connection on page 5-205 except it uses a short beam stub welded to the column and gusset plates and the actual beam is connected to the beam stub.

 

[WiSEiwish]

Sorry for the lack of clarity. My question was what Jittles was assuming. I do plan on attaching the beams to the columns! The wood to steel is new to me, so I was wondering if there were common wood to steel bracing details. If i could attach the gusset to the column then i could make sure that the beam to column connection has adequate strength to resist lateral loads before passing them into the brace.