Unbraced Length of a Column

[KOTOR1]

I have situation where a steel lintel (wide flange) supporting reinforced masonry is supported by a steel column in the middle due to the length of the steel lintel (steel lintel is continuous over the column). Will the column be designed with K=1 in both directions or should column be designed with K=1 in one direction and K=2 in the other?

My boss says that since the masonry is reinforced and is braced back (steel angle - 2'-0" above steel lintel) to the joists as well as designed for out of plane bending and braced at the top with the deck, K should be one in both directions.

 

[KOTOR1]

Yes. This has been the practice at the office. I am new to the firm and wanted some clarification. The other engineer told me he has done projects before where he assumed the LTB length to be 8'-0" due to the braces in a similar situation but a larger span. Vertical stiffeners are provided at the beam web at the column. Welded studs are provided at 24"o.c at the top flange in grouted bond in masonry.

I would rather move the brace to the top of web of the beam but the architect is not allowing itsince it was done earlier with brace 2'-0" above top flange.

 

[MJB315]

I stand by the original statement. The effect of floral genitalia on column buckling is often not fully appreciated by designers.

LOLZ

"We shape our buildings, thereafter they shape us." -WSC

 

[KootK]

I would rather move the brace to the top of web of the beam but the architect is not allowing itsince it was done earlier with brace 2'-0" above top flange.

The 2' offset doesn't bother me at all. The masonry ought not have any difficulty cantilevering down from the 2' from the braces.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KOTOR1]

So the beam will have a LTB length of 8'-0" due to the braces. This would help at the top of the column too. Hence, it's OK to use k as one in both directions?

 

[KootK]

Not sure what the 8' dimension is but yeah, K=1 both ways for the column.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.