Compressive Strength of Old Brick Wall

[marinaman]

I've got a client that wants to bear a new steel beam on an old brick wall...just to support a new folding partition.

The loads are small. I've calculated them to be about 2.7 kips when the panel is all folded up at one end.

What do you guys use for the allowable compressive strength of masonry on an old brick wall such as this?

Just to check, I calculated a short length of wall, 8" thick, and about 9'-0" tall for buckling under load, but am unsure about the allowable compressive strength I should use in the calculation.

The smallest value I see in table 5.4.2 of ACI 530 is about 100 psi. I was thinking of using this small value, times the buckling calc of about 0.22, and I get about 22psi allowable.....when spread over about 2'-8" length of wall, I only have about 11psi actual....which seems ok.

Any opinions?

 

[SLTA]

How old is "old"? Are you talking 1960s or 1500s? And where are you located, in the world?

There are lots of great old masonry resources out there and I'll be happy to help once I know what you're dealing with.

(and as a side note, just since it's been a while... we're not all guys!)

 

[IsaacStructural]

well intuitively 11psi for compression loading is quite small, so I imagine you will be ok. Before loading you could have the wall tuck pointed to make sure there aren't any specific deficiencies.

Did you include existing loading on the wall, or is unloaded in the vertical direction, outside of its own self weight?





M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)

 

[marinaman]

I'm in the Southeast. The brick is from about 1945 or so and is solid.

slta - Around here, "you guys" is not gender specific. For example, when I coach or officiate girls sports, I often say terms such as "you guys need to quit pushing" or "you guys have got to play some defense". Good grief....have we gone that PC these days to pick a person's comments to that level?

The loading on the wall is only from this beam. The new beam will be placed away from any area where any other loading is located.

 

[DST148]

@marinaman> try thread507-44927 . You might find some more useful information and links.

 

[dhengr]

Marinaman:
Your problem has several different levels which you must evaluate. There are laboratory/NDT methods for actually testing the compressive strength of the brick/mortar system insitu. The first problem..., your beam will be bearing on a fairly small bearing plate on this brick/mortar system and this condition must not exceed the masonry bearing strength. Then, that load will corbel out to your 2' - 8", or more, by 8" column section in the whole wall. This must not buckle, as you suggested you had started to check. Both of these problems are also dependant upon how the several wythes of brick are bonded together to make up the 8" wall. Are you sure you are not bearing on only one wythe of brick (a veneer?) which is not bonded to the other wythe, even though the wall is 8" thick?

 

[XR250]

Unless the mortar has reverted back to sand, 2.7 kips should not be a problem at all.