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I am interested in the capacity of HSS "round" columns, readily available to fabricaters in the Northeast USA.  I was wondering:

1) the maximum wall thickness available with a 3" dia. column, 3 1/2" o.d. max?

2) the maximum allowable load, for the above column, tabulated by AISC given,
   a) 10' unbraced in both axis
   b) pin-pin connection
   c) no eccentricity

Thanks so much


The capacity of a 10' high double extra strong steel pipe is 60,000 pounds.  The wall thickness of this pipe is 0.6".



Check your AISC manual.  There are tables that list column capacities for different unbraced lengths for different column sizes.


When the required wall thickness gets to be too extreme, you may want to consider going to heavy wall mechanical tubing. If the exact OD is important, it can be turned down from a larger size.

This may not be practical for longer pieces, but I have seen it done for larger sizes of pipe (e.g. 10"xxstrong) used in special applications.


Thanks for your responses.

The problem I ran into was that I specified the DBLX strong column and the steel manufacturer was suggesting the column was difficult to obtain and very expensive.

I usually spec. out pipe or square HSS tubing.  I was not sure of round HSS or the allowable capacities.  I found these capacities both for LRFD and ASD on the Steel Tube Institute web site.  One interesting comparison between the round HSS column and the Extra Strong Pipe column is as follows:

     3.5" OUT. ROUND CLMN (50 ksi)  3" EXTRA STRONG (36 ksi)
6'               63 KIPS                  52 KIPS
7'               57 KIPS                  48 KIPS
8'               51 KIPS                  45 KIPS
9'               45 KIPS                  41 KIPS
10'              38 KIPS                  37 KIPS
11'              32 KIPS                  33 KIPS
12'              26 KIPS                  28 KIPS
13'              23 KIPS                  24 KIPS
14'              19 KIPS                  21 KIPS

The comparison between comparable thicknesses shows the HSS round a stronger column up until the 10'-11' length.  At that point the Extra Strong Pipe is stronger.

Eventually I will do the calculation for my own comparison.

Anyway, FYI I called two Steel Manufacturers regarding the availability of a DBLX strong column.  Both of them located the columns and gave me a tentative price within a day.  The price was about .45 cents a lb, which to me seems reasonable.


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