Distribution of Point Load on Masonry

[IreStruEng]

Hi everyone,

My first post so I hope I'm linking the photo correctly. In the attached image I am verifying the spread of the point load and designing the wall. My own intuition is telling me that the spread will only be present through panel A and no load will be spread through panel B. I've never done masonry design before so please correct me if I'm incorrect.

Thanks

 

[phamENG]

I'd say it depends on the detailing of the wall. Does wall A extend to the outside corner with a vertical joint between it and wall B? If so, you're quite right. If the masonry interlocks around the corner, then your assumption is conservative, but probably not TOO conservative. Unless it required a significant change in the design, I'd stick with what you're thinking and detail for it.

 

[JLNJ]

Simple statics would say that the reaction provided by the wall needs to be centered under the reaction imposed on the wall. This means the intersecting wall doesn't help or the resisting reaction would no longer be centered on the first wall. The is the simple, conservative approach as phamENG points out.

For there perpendicular wall to help, the analysis is much more complicated. Even the simple condition of the reaction right at the corner is not so simple if you are hoping to spread the load out along both walls. A moment couple in the plane of the walls would need to be developed and resisted by something, and even then I'm not sure the walls would actually act that way.

 

[MIStructE_IRE]

Through panel A only in my view.

If the load was applied right on the corner I’d agree that it could be split between both panels (provided they blockwork is in fact keyed in) - but in this case its not. So panel A only I’m afraid.

 

[IreStruEng]

Thanks for the replies guys, much appreciated!

 

[KootK]

My own intuition is telling me that the spread will only be present through panel A and no load will be spread through panel B.

1) I disagree with that. If those two walls are keyed into one another, as I would expect, there will unquestionably be a good deal of load spread into wall . How could there not given that the walls are forced to move in tandem and the joint?

2) The reaction to the applied load does indeed need to be centered under the load. However, that "reaction" can and will include the effect of rectifying, in plane wall moments as shown below. Luckily, your walls will be wicked strong and stiff for this purpose, unless wall [B} is very short. These same, in plane, rectifying wall moments are also part of the deal when you're dealing with a single wall and a load applied near the end. In fact, they're even part of the deal with a single wall and the load applied in the middle as it's a prerequisite to lateral load distribution of any kind really.

3) If it yielded a reasonable result, I'd be happy to apply the simplification of assuming that the non-perpendicular wall does not participate in the the load spread. If that didn't yield a reasonable result, however, I also wouldn't hesitate to rope in the contribution of wall to help out. Wall [B} will participate, after all.

 

[KootK]

A very similar situation is ubiquitous in concrete basement design. In my opinion, it doesn't much matter if the load is at the corner or just near the corner since the shear transfer capability of that joint is significant.