HSS joist stiffener plates

By swnorris (****)

Date 05-21-2004 12:35

Hi zazing,

I'm no engineer, but maybe what you're looking for is in D1.1 Section 2, Design of Welded Connections. Part A is for Common Welded Nontubular and Tubular, and Part D is for Welded Tubular for Static or Cyclic Loads. I can't picture in my mind exactly where you're locating these stiffener plates on your HSS joist without seeing a drawing, unless you're using them as gussets. Gussets are referred to as reinforcement in D1.1 under Limitations of the Strength of Welded Connections at 2.24.2.2, and Table 2.4 Fatigue Stress Design Parameters. You may want to check out the commentary in C2.24 also. The only thing I see regarding "stiffeners" is in 2.8.3.4, which addresses transverse stiffener welds, but that is under Part B Requirements for Nontubular Static or Cyclic Loads. Maybe the word you're looking for in D1.1 is gussets, not stiffener?

By jwright650 (*****)

Date 05-21-2004 14:25

Hi Scott,
Wonder if the stiffeners are going inside the tubing at each end to aid in the prevention of crushing the tubing at the bearing points at each end?
John Wright

By zazing Date 05-21-2004 14:42

I'm using stepped connections: 1.5x1.5x0.1875 web members and 3x3x0.25 chord members. I'm right near the limit of plastic chord wall failure at the ends of the joist, so for those joints they(*) recommend adding a simple plate to reinforce the chord wall where the web meets the chord. This would work both on K and Y connections. They say I can substitute the increased thickness into the equations but don't offer how to compute the dimensions of the plate, other than the quote I orignally gave.

* "They" is: AISC HSS Connections Manual p8-13.

From 2.24.2.2 "...may be reinforced by increasing the main member thickness or by use of diaphragms, gussets, or collars." OK, I guess that's a "provision" but I was expecting more meat.

By H.Dibben (*)

Date 05-21-2004 16:22

I am not familiar with that particular AISC document, but have seen other guidelines for tubular connections.

I would say the plate should by a little wider than the chord (say 4") so you can get a good weld along the sides, and the length can be estimated by estimating the length of the plastic failure of the chord face.

A simpler solution might be to use HSS 2" x 2" bracing members at the ends of the joist where this is a problem.

By ziggy

Date 05-21-2004 20:39

Try AISC's Steel Solutions Center.
Their toll free number is 866.ASK.AISC.
Their engineers were very helpful.
ziggy