Steel Frame-Infill CMU vs Load Brg CMU 1

[STR04]

Can anyone tell me their opinion, experiences using a steel frame with infill CMU vs load bearing CMU? I'm thinking there is a decrease in time of construction because you can dry the building in earlier but not a material savings. What are everyone's design thoughts on this and how do most contractors feel about the comparison?

For infill CMU I'm think of tucking 8x8 columns flush in a wall to avoid bump outs and connecting the beam above to the CMU bond beam below with a series of clip angles with slotted holes (vertical) and epoxy bolts. The design intent is to allow the beam to deflect but transfer later loads into the CMU.

##### -Steel Beam Above
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^^^^ - Angle Clip attached to CMU Bond Beam
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* @ * ^
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* @ * - Infill CMU wall beneath Steel Beam
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* @ *
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[SperlingPE]

First question
Is the cmu needed for some rating or separation?
Second question
What is the floor construction?

I would tend to stay away from two trades unless needed for some certain reason.

 

[STR04]

The CMU is used as backup for building enclosure which complicates the details when you have rated wall requirements. The floor construction is steel beams/joists with concrete floor or metal roof deck. There is no need to mix trades if the steel erector can put up the frame and have the block layer come behind.

 

[haynewp]

I like to use load bearing cmu for 1 to 2 story. But many architects and contractors like to have steel support with cmu infill. I would really like to see a complete cost and time comparison breakdown between load bearing cmu and cmu infill for 2 similar projects done in the same city. I normally let the architects/owners decide whenever possible so they don't come back to me b*tching about why I chose system "X" vs "Y".


When things are steep, remember to stay level-headed.
-Horace

 

[STR04]

Horace,

Does your infill typically align with the columns or do they bump out into the occupied space?

STR04

 

[haynewp]

I keep the exterior side face shell of the cmu continuous and the columns bump out into the spaces. Architects show furring around the columns in the spaces as needed.

I think I remember doing one small building where I used HSS columns that fit completely within the cmu wall. I just noticed you are thinking the same thing with 8x8 columns, 7x7 or less may fit a little better unless you are using >8" cmu thickness.


When things are steep, remember to stay level-headed.
-Horace