built-up column

huangyhg

built-up column
this is an industrial type structure where we have 2 nos. 40' high columns spaced closely and these column need to act as one section for axial and bending.
the web of one column is oriented 90 degrees in reference to the other column( i.e flange of one column is facing web of other column.
for some reason(one of them is size of columns are different w24x68 and w18x40) we can not provide lacing or battens  to join columns together.
my question is :
if we connect the 2 w shape columns(with 2 feet c/c spacing  in between)  by "horizontal" w beams, will this be a "built-up section" or not?
the vertical spacing between w beams will be approx. 4-5 feet. the w beam will not be rigidly connected to columns.
if not , is there any other way to make these columns to behave as built up section so that there combined properties can be used?
thanks

the two columns would not act together, but the one with the braces into its web would be braced by the other column.
the key to them acting as a bending unit is shear transfer.  if you have horizontal beams between them with pinned ends, it can't transfer the shear as they try to "slide" relative to each other.  can you put some intermittent frames?  say, two horizontal beams 3' apart with a diagonal between them?  if you could put a few of those in there, you could approach a fully laced condition.
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