STRENGTH DESIGN OF REINFORCED CMU JAMBS - GRAVITY & OUT-OF-PLANE

[oengineer]

I am new to CMU design & I am looking for an example of a CMU wall jamb design. I have access to the Masonry Design Guide , but I am not finding an example for jamb design in the design guide. Would pilaster be considered another name for the jamb in the design guide?

I have been told that the CMU wall jamb design is considered a flexure-axial design. If anyone knows of an design example, that would be great. Suggestions/comments are appreciated.

 

[oengineer]

Any text showing an example of an CMU wall jamb design would be helpful.

 

[jayrod12]

It is just a pilaster, or a column, subject to both gravity and out of plane loads. Designed almost exactly like concrete.

 

[oengineer]

@jayrod12

Thank you for that clarification. For some reason, I am not seeing an explicit strength design example for a reinforced pilaster in the Masonry Design Guide.

@everyone
If anyone familiar with the Masonry Design Guide could point me in the right direction, it would be appreciated.

 

[masonrygeek]

As mentioned in your other post, take a look at David Biggs' articles in Structure magazine:

https://www.structuremag.org/?p=4474

and

https://www.structuremag.org/?p=3834.

 

[oengineer]

Is anyone aware of where to find a Strength Interaction Diagram Spreadsheet for CMU pilasters?

I know that The Masonry Society's website has spreadsheets Interaction Diagram Spreadsheet, but I do not see any on their website that could be used for pilasters.

OnThe Masonry Society's website, I see spreadsheets for "Design of Reinforced CMU Loadbearing Wall","Effect of Openings on Reinforced CMU Wall Parallel to Joist for Axial Load and Out-of-Plane Flexure", and "Reinforced Shear Wall Design for In-Plane Flexure and Shear" , but not a spread sheet for CMU pilasters.

Is there a website with a reliable design spread sheet for this task?

 

[jayrod12]

I think you're getting way to stuck on terminology.

Masonry design, much like concrete, doesn't really care an incredible amount what you are calling the member. Look at the stresses imparted on the member being designed and make sure that the appropriate resistances are provided. I can't speak directly to the Masonry Design Guide you're alluding to as I practice solely in Canada, however I know that our code discusses columns subject to combined loading and is in Limit States Design (similar to LRFD)

 

[oengineer]

@jayrod12

Thank you for your comments. Based on example 12.4.4 I found in the textbook, Masonry Structural Design by Richard E. Klingner,their is a spread sheet I can use on The Masonry Society's website for the Interaction Diagram.

@everyone
Question: Anyone know of any code requirements for deflection checks of pilasters?

 

[oengineer]

Would the wall deflection criteria be applicable to the pilaster?

 

[jayrod12]

Yes

 

[oengineer]

@jayrod12

Where in the code does it mention that the wall deflection equations can be applied to the pilaster? The reason I ask is because TMS 402-13 Equations 9-29, б =(5M_uh²)/(48E_mI_n and б = (5M_crh²)/(48E_mI_n)+5(M_u - M_cr)h²/48E_mI_cr, are stated to be used for walls.