Plate subjected to weak axis shear along with strong axis shear, axial and bending

[Nitesh Sadashiva]

Hello,

I have a condition where beam to column web extended shear plate connection subjected to weak axis shear simultaneous with the strong axis shear, axial flexure and torsion. The plate is able to withstand all the load independently. But I am concerned about the plate interaction for the combined loads. I could not find any reference for an interaction equation with the combination of all these loads. Any suggestion/ reference will be much appreciated.

 

[DrZoidberWoop]

Change the connection to a pair of double angles or an end plate. The analysis rabbit hole you'll end up going down isn't worth the hourly rate you're being paid.

 

[rb1957]

"weak axis shear" = transverse shear ... and bending

von Mises stress combines multi-axial stresses.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[Struct123ure]

The Aluminum design code has more combinations then the hot rolled steel so you can see attached textbook "Aluminum Structures_ A Guide to Their Specifications and Design-Wiley-J. Randolph K, Robert L. F(2002)" on page 213, 214. The trosion can be resolved into additional shear and longitudinal stresses and you could use the equation directly.
But I think you are better off doing as rb1957 suggested using von Mises stress combination. See attached extract from the textbook above which gives more guidance on how to check Von Misses Stress pg 214.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1695653352/tips/EXTRACT_Aluminum_Structures__A_Guide_to_Their_Specifications_and_Design_xoqyas.pdf[/url]

 

[rb1957]

and so the weak axis loading would just be another term ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[271828]

I would adapt the AISC Manual Eq. 9-1 for this.

If the weak axis shear is not tiny, then good luck. Lol

 

[WARose]

You could probably turn those forces into principal axis stresses that could be checked via AISC's combined stress formula(s). The version of AISC I use doesn't check shear combined with principal stresses because AISC typically has the allowable shear low enough where it will not be a issue in a combined stress state (like the Von Mises criteria, which is another option you could check by).

By the way, you talked about transferring torsion via this.....usually transferring torsion via shear connections creates excessive stress in the beam's (with the torque) web. That usually is a problem well before the stresses in the connection hardware get to be too high. (I.e. the web is the weak link.)

 

[ProgrammingPE]

Equation 9-1 in AISC's Steel Construction Manual comes from a journal article written by Bo Dowswell called "Plastic Strength of Connection Elements". The manual shows the simplified version for in-plane loading only:

Mr/Mc + (Pr/Pc)² + (Vr/Vc)^4 ≤ 1.0​

You will need the full version that is found in the paper since you have biaxial loading and torsion:

[(Mrx/Mcx)^1.7 + (Mry/Mcy)^1.7)]^0.59 + (Pr/Pc)² + (Vr/Vc)^4 + (Tr/Tc)² ≤ 1.0​

This comes with the important caveat mentioned in the paper: "Experimental results are available for four load interaction cases: axial-flexure, shear-flexure, torsion-flexure and biaxial flexure. For these cases, the proposed interaction equation compares well with the experimental results. However, future testing may be needed to validate the equation for other load interaction cases."

Using Von Mises Yield Criterion for the check would be an appropriate, conservative method to check the connection. It can determine when yielding will be first initiated. AISC's approach to steel design, however, uses the plastic strength. In the "Connecting Elements Subject to Combined Loading" section of Part 9 of the manual (right before they provide equation 9-1) states, "Designs using beam theory, and other models that are based on a first yield criterion, underestimate the strength of connection elements. Because the AISC Specification is based on strength design, the combination of connection design loads based on a plastic strength approach is appropriate."

Structural Engineering Software:

http://www.structuralcentral.com/tools/steel-connection

Structural Engineering Videos:

http://www.youtube.com/structuralcentral

 

[WesternJeb]

In lieu of doing some of these more rigorous checks. Could you just detail the joint or area differently so that multiple elements are taking a few of the different stresses apiece?