Hilti Profis Alternate 2

[Bowsers]

Hello,

I'm doing analysis on an eccentrically loaded bolt group, that is experiencing loads that are both eccentric and out of plane of the faying surface.

Hilti Profis does this analysis, you can apply Mx, My, and Mz, as well as Fx, Fy, Fz from any point.

I've gone through their design guide (where they validate the software's ability to interpret the loads). If would even use it, except my base-mount material is wood, which has a significantly lower E than concrete.

I did manage to find one spreadsheet that does quite a bit of the load generation analysis, but it fails to account for the changing neutral axis location.

Does anyone have a spreadsheet they could share that does this analysis, or an open source hilti alternative that allows for inputting E of wood into the equation?

 

[dold]

Retired13, I think OP is trying to analyze: 1) bearing stresses between a steel plate and a wood substrate (PSL and LSL); 2) the resulting forces in the lag bolts.

OP I'm still curious about what this detail looks like. 390psi should be well within allowable limits for bearing stress perpendicular to the grain for most manufactured wood.

 

[Bowsers]

@stevenh49 - I'm using the strain compatibility based on the the rows of lag bolts.

@dold - I'm not particularly concerned about crushing the wood, though it would be nice to show that it's fine. The concern is the resulting tension of the lag bolts. I originally sized them based shear forces and direct tension and had neglected the additional tension as a result of the moment. The DCR's were ~0.9 and the plan checker wanted additional validation.

The plates are 1/4" thick steel bent plate, lagged to the wood members and connected at the end of the steel. The bent sections are 90 degrees, and stick out about 4". (btw did the appropriate steel checks to ensure the plates are adequate)

 

[Ganesh Persaud]

The best way to analyze the bolt group, see AISC manual table 7-6 to 7-13 for the eccentric distance to bolt group.

These tables give the bolt group coefficient for typical. However at the beginning of chapter 7, there is a formula to calculate the bolt group coefficient, C’.

After computing this, see equation 10-4 to compute the max moment. I think there’s an equation there for shear.

You need to calculate the resultant bolt group force along the horizontal line.

Theta = sqroot (taninverse(Vu/Pu))

After this, calc the bolt clear distances which you would use, depending on the no of bolt along the line, or in no of bolts in a single column, check the bearing and tearout strengths and compare with the actual.

After which, calculate the net area of the section that’s carrying shear and get the uniform tension stress factor from AISC 14th fig c-j4-2.


There are eaquations utilizing These to calculate the Block shear resistance provided.