Unequal Angle or bent plate Design 2

[ash060]

I am designing a releaving angle for a brick veneer. The veneer will be releaved every couple of stories, no back-up tube just the angle will be carrying the brick. I have to keep the thickness down to 3/8" because of the joints in the veneer. The span is 8' where the angle is picked up by a vertical tube. Deflection must be l/600 according to ACI 530 for veneer. After looking in the AISC code I saw the equation for LTB in Unequal leg angles about the principal axis and it included a Beta w factor for determining the moment capacity. And the equation looked pretty complicated, it was in the commentary of AISC Spec.

Does anyone know of an example that shows how to calculate Beta w?
Will an unequal leg angle always bend about its principal axes or can you get it to bend in the x and y axes?
What is the deflection clac for an unequal leg angle?
Since i am not loading the angle thru the shear center, does that effect the equation given in AISC Spec?

Any help would be great

 

[hokie66]

Based on my experience, 8 feet is too far to span an unbraced brick relieving angle, but for the actual analysis, will defer to others. Just a word of caution which your post seems to cry out for: the joint at the relieving angle must be wide enough to accommodate both the angle which you finally select and the soft joint below the angle. Don't forget brick growth!

 

[rgerk]

The Beta w can be found in a table in the Commentary on the Specification for LRFD/ASD of Single Angles.

ASD 9th Edition - Table C5.1, page 5-323
LRFD 2nd Edition - Table C5.1, page 6-298

The axis of bending for an unequal leg angle is dependent on it's lateral torsional restraint. It will bend about the geometric axis (x and y) and the principal axis if it isn't restrained. Read the commentary noted above on flexure.

Deflection should be 5wl^4/(384EI) for a uniformly loaded member.

The vertical load will go through the shear center, but you will have an associated moment to go along with it. Hopefully, someone else can chime in on this one.

 

[ash060]

The Beta w is only give for certain angle sizes, I will probably be using a bent plate that does not have a given Beta w value, and I can't follow the equation given in the commentary, does anyone know of an example using that equation?

The 13th edition gives an equation for LTB in unequal leg angles that says principal axis, it does not say it is for the geometric axis

Also the commentary says that an equal leg angle will deflect 1.56vertical and 0.96horizontal of the calculated deflections using the geometric properties, will it be the same for unequal leg angles?

Thanks for the help so far

 

[miecz]

Take a look at the Brick Industry Association (bia.org)Technical Note 31B. It doesn't answer your question directly, but may give some insight into the problem.

 

[structuralaggie]

I have an old spreadsheet someone wrote that was for masonry shelf angles per Grimm and Yura's paper titled "Shelf Angles For Masonry Veneer" in the "Journal of Structural Engineering", Vol. 115, No. 3, March, 1989.

If you can track this down, you might find it helpful.

 

[prsconsultant]

I have a shelf angle design spread sheet. If interested I can email you a copy of it. Let me know.

 

[WillisV]

There is a pretty good spreadsheet for shelf angle design posted on:

http://steelutilitiesonline.com