Multi story brick support

[bvsiq]

I was asked to look at a 12 story concrete frame condo bldg with brick veneer- called for relief angles at every floor, anchored to slab edge. Finding out that the vert leg of the angle is as much as 3" away from concrete edge! And the brick is up right against the bottom of relief angle!

The 5/8" bolts at 24" oc cannot support brick with that eccentricity. The brick should support itself on the concrete ledge below- 40 pdf x 120' = 4800 plf or 100 psi - low.

Then with brick supporting itself and free to move upward, need to support laterally. The metal stud wall ties may or not be connected properly. Thinking of vertically slotting the angle holes to allow the angle to move vertically. The bolts would only provide lateral support.

What do you guys think?

 

[hokie66]

Suggest you read this thread.

thread507-456379

I think your "condo bldg" will have lots of problems with its brick veneer, no matter what you do. I worked on one similar to that once, and we demolished the veneer and did it right.

 

[JAE]

Per TMS 402 you have to vertically support anchored brick veneer at each floor above 30 ft. (see TMS 402-13, section 12.2.2.3.1.3)
TMS is referenced by the IBC code.
Your idea would violate that code provision.

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[bvsiq]

JAE, thanks for responding.
Yes I was aware of that reqt,
Sad, because the weight can definitely be supported by the brick itself on the ledge.
Will have to discuss with bldg officials.

Thanks again

 

[JAE]

The code is attempting to limit large sections of veneer collapsing all at once during an extreme event or fire.

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[masonrygeek]

While your proposition might work in a perfect world, there are too many things that could go wrong. What happens if the bolts are tightened too much and you don't have the vertical movement that you anticipated? Cracking. What happens if the brick moves up under a window that is attached to the backing? Cracking. While brick veneer can be self supporting up to 1,000 ft high without crushing, the growth of the brick over time and its attachment to the backing must be considered. That's why the code has recommendations for shelf angles (I don't like the term relieving angle). I remember a tall building (12 stories?) that had a free-standing veneer. They used dovetail slots to accommodate the vertical expansion of the brick and creep of the frame and there weren't any windows on that particular facade to worry about. Unfortunately, someone forgot to remove the insulation out of the dovetail slots and caused the dovetail ties to rotate and fail. Neat idea, but there were issues. You can always do engineered design that replaces the prescriptive requirements, but you need to consider everything.

 

[bob33]

The Masonry Society has a recent webinar available entitled Rational Design of Masonry Veneers and Shelf Angle Supports.