How to calculate max load

[Limp Arbor]

Assume I have a SYP 4x4 post and on top of it I have one of these

top member, or top of the T would be a SYP 4x4, 3' long with 2' to one side of the post and 1' to the other side of the post. On the 2' side would be 3/4 plywood triangles nailed (maybe through bolted) to the sides of the post and the 2' side of the T.

How do I calculate the maximum load on the 1' side before the top 4x4 will shear off? This load would be gradually applied.

I have found span charts and tables but nothing to determine the failure load of a 4x4 cantilevered 1'.

Ascii diagram (fixed font): side view how much v ____________________________________ | . . . . . . ___________ | |__________________|___________|_____| \ | | \ Plywood |___| \ traingles | . | \ on both | . | \ sides | . | \ | . | \ | . | \ | . | \ | . | \ | . | \ | . | | |

[Mike Marlow]

Impossible to conclude until you determine the characteristics of the steel plate that makes up the T-head. It's not about cantilever - it's about the bracket you are using to build what is almost a cantilever. You need to contact the manufacturer of the bracket for this information. It's just not a wood strength question.

[todd]

First, I suspect that some kind of shearing of the 4x4 will not be the primary mode of failure of this structure. How tall of a 4x4 are we talking here? Any thoughts on how much load you are thinking about putting on?

todd

[Jim Behning]

What is the dimension of the 4x4? Their product description does not state that it fits a 3.5x3.5" piece of lumber. "DESCRIPTION: This product is made to fit 4x4 Ellis Shores only. 4x4?s or 4x6?s can be used for T member." Lumber used in commercial construction may be actual dimensions, not residential dimensions which is surfaced 4 sides to some nominal dimension like 3.5x3.5" instead of 4x4 it is listed as. Sometimes that construction lumber may be of woods like oak without knots or nominal knots. SYP is often pretty knotty.

Simpson has a good number of fasteners used in residential construction.

An engineer might tell you what the cantilever load might be but with such a tiny piece of lumber subject to knots is might only be 10 pounds. The engineer would probably not risk making a prediction using a non-standard construction method. SYP 3.5x3.5" posts are generally installed and loaded in a vertical way, not horizontally. I know that I would never try to build anything with any significant load with syp

4.x4.

You left off what you are trying to do and what the weight is on that cantilever.