wall height

[CivilEngineerjoin]

what is limitation for height of masonry wall if it's single story.
can i use 8-10 in wall for 25-30ft high. It's load bearing wall.

 

[msquared48]

Normally, the limiting H/t ratio is 35, so you are looking at a 10" wall for 25 feet, and a 12" wall for 30 feet.

However, if my memory serves me right, I believe that the PCA Slender Wall Design brochure allows ratios up to 50. There are other design considerations too, plus it's been a while since I did this, the code has probably changed, and my book is packed away.

Mike McCann
MMC Engineering

 

[dik]

Depending on the code... in our locale, the maximum h/t for bearing walls is typically 18 or 20 based on the actual wall thickness, not nominal thickness... this limits your 10" block wall to approx 16'...

Dik

 

[DST148]

Reference - ACI 530-05
Chapter 2- Allowable Stress Design of masonry - Columns: ratio between effective height and least nominal dimension shall not exceed 25. There are no h/t limits specified for walls.

Chapter 5 - Empirical Design of Masonry : Section 5.5.1
Type of Construction l/t or h/t
Bearing Walls
solid / fully grouted 20
All other 18
t is the nominal thickness of wall.

 

[CivilEngineerjoin]

if i will follow method based on chapter 2 and design 8 inch interior bearing wall which can take 1 klf load and out of plane seismic load, then is this possible to use?

 

[dik]

Doesn't matter... the height intended is too much... as noted and as based on DST's comments, you shouldn't be going higher than about 16' with 10" block... You can reinforce it and design it using code portions for slender walls, but you will not achieve a 25' height... You need reinforced pilasters or structural steel to provide the lateral support.

Dik

 

[spats]

I don't see where DST said the height was too much. There is no h/t limit if you're going to design per ACI 530 Chapter 2. Forget the empirical design of Chapter 5. However, that being said, you may get 10" to work for 30', but not 8". The seismic and/or wind stresses would probably be too high even if the wall is significantly reinforced.

 

[dik]

...go for it spats...

I've used engineered masonry long before it was codified... both for slender walls and for twenty storey apartment buildings. It's going to be really difficult to get the last couple of feet of the 30' height to work... and, I'd probably leave the scaffolding in place... even if no seismic or wind...

Dik