Masonry Wall

[joemarch]

I have a situation where I have a 42' high 12" masonry wall which is exposed an exterior wind load (stair tower). So I'm treating it as a simple span. I can reinforce it enough to take care of the stress. Will deflection be an issue? How is deflection calculated? Thanks for your help.

 

[whyun]

Consider the height to width ratio. If the width of stair tower is narrow, you do not have to consider the wall as a simple span for the full 42' height. You may design the wall to span horizontally between the cross walls, then design the cross walls to take the uniformly distributed load as a shear wall.

 

[joemarch]

My wall is about 30' long. I still think it would be much easier reinforcing vertically versus horizontally with that sort of span. just my 2 cents.

 

[whyun]

Wouldn't you need horizontal reinforcing regardless?

With the wall spanning vertically, deflection may be calculated using the formulas outlined in 1997 UBC Section 2108.2.4. I do not have my copy of 2000 IBC and I haven't started using it (not adopted in my area yet) but I'm sure the concept is the same.

If you are in IBC-land, please respond where you find the code section.

 

[joemarch]

In the past I've always used Dur-o-wall for horizontal reinforcing. Maybe in this situation this isn't enough shear reinforcing. I was thinking that providing bond beams and horizontal reinforcing approx. every other course would be more work than just providing vertical bars.

I did go back to my old 94 UBC and found my deflection criteria.

Lucky me, I am in IBC land. I guess I did find the criteria in section 2108.5. I guess I was thinking I could find it in one of the 18 million references the IBC uses.

 

[SacreBleu]

Looking at this realistically, what you have is a 2-way bending situation, especially because you have a rectangle 30' x 42'. There are plenty of sources to help you estimate the maximum bending moments vertically and horizontally.
The deflection will realistically be much more manageable than the super-overconservative assumption of a 1' wide strip spanning 42' vertically.

 

[joemarch]

SacreBleu, I don't know if designing that way is a good way to approach this since a vertical control joint is going to be needed somewhere in this wall.

 

[SacreBleu]

If the stair tower is a square, 30' by 30', what is the need of the control joint?
If there is indeed a MCJ, then you are correct.