Lateral support for masonry walls

[n1cq]

Would you consider a bond beam to meet
the criteria for use as lateral support for a CMU wall as prescribed in ACI 530, 9.5.2 ??

We have 15' between floors and h/t>18 for an 8" block wall. Increasing the wall thickness is not an option.

n1cq

 

[JAE]

To which ACI 530 edition are you referring?

 

[UcfSE]

Do you mean section 5.5.x? I would say no, that bond beams do not have the required stiffness to act as a lateral support, whether or not they have the strength. You can try designing some kickers that go to your roof diaphragm and support the masonry laterally. I've done that before and it usually works out fine. Make sure to check your attachments of your kickers, whether with an embed or something else, plus additional forces into your roof members from the brace. I like to use an angle that's attached with epoxy anchors or expansion bolts.

I notice that this is an empirical requirement, if I am correct that you are using chapter 5 instead of 9. If you engineer the masonry according to chapter 2 this requirement is eliminated but you have more equations and stuff to check, such as calculating all the strengths instead of using tables. This could make what you have work if all the engineering works out but I would suggest you at least consult someone familiar with engineered masonry. Though I always engineer masonry, I still encounter h/t limits when doing designs in south Florida where they have special requirements.

 

[n1cq]

UcfSE

Thanks for the advice.
Yes, it looks like I'll have to use Chapter 5, the working stress design methodology. I was trying to simplify the design by using Chapter 9, empirical design.

I'm designing an elevator shaft from 8" CMU which will be 32' high and 20' at its greatest width. The 20' wide wall will not permit a simple means to satisfy the prescriptive h/t ratios, so rethinking per Chapter 5 makes sense.

Thanks much again.

 

[3dboy]

If you are designing a 32'-0" high 8" masonry elevator shaft using empirical design you are not going to get it to work, nor will you be guarding the safety of the public. Also you need to check what seismic design category you are in as this brings some rather stringent detailing requirements. there are very few places in the united states where you are even allowed, by code, to do what you are trying. Most states have adopted the IBC code and you really need to look into what the seismic requirements are