Tieback Bearing Plate Anchorage

[Thoughful]

Hello,

I am working on determining the bearing plate size for tieback anchorage. I am staring with a square plate of 8" x 8" that has a wedge plate on top of it. I am not sure if AISC can be used to check for plate buckling, bearing strength etc. There was another thread that mentioned Roarks formulas, I am not familiar with the book. I checked it out and I came upon formulas for flat plates with straight boundaries. I am not sure if they will be applicable on my case. If anyone has a good reference and or can provide me with some guidance, it will be greatly appreciated. Thanks!

 

[driftLimiter]

A sketch will be very useful for you to receive good responses here. Some loading information is a big plus.

 

[Thoughful]

Thank you. I am designing for FTL of 66 kips. Here is a sketch of the bearing plate and the tieback.

 

[JLNJ]

Those are some thick plates and short spans. I don't see a lot of flexure here.

What are you bearing against? I must admit I'm a little confused by the drawing snip.

 

[Thoughful]

The Plate is 2" thick and it is bearing on concrete

 

[driftLimiter]

Draw a FBD of the plate in question. Its not clear how your plate is loaded, you will need to identify the loading and support conditions well in order to determine the applicable limit states. Looks to me like you just have bending about the tie not sure where plate buckling came up in your mind but I dont see it from the sketch.

 

[Thoughful]

I attached the FBD. However I feel my load is ridiculously high. I am trying to find the bending stress in the bearing plate. My load is about 66 kip, which will produce a uniform load of 7.6 ksi. I feel my approach might be overly conservative.

 

[driftLimiter]

I drew some sketches while thinking about some of the different considerations on this.

If the support diameter is large compared to the load, then bending is important. for plate bending equations from Roark's or similar. Shear in the plate is also a limit that would be important. If alot of deflection is allowed then the plate will rotate on the support and the bearing pressure would only be distributed to the edge of the support ring.

By the apparent proportions of your drawings, your. Case seems very much like a typical plate washer. Link