Wood dowel bearing strength in concrete

[DTS419]

Note 3 in Table 12E of NDS 2018 assumes dowel bearing strength, Fe, of 7,500 psi for concrete with f’c = 2,500 psi.

How do you get 7,500 psi bearing strength for 2,500 psi concrete and be in accordance with ACI 318-19 22.8.3?

 

[driftLimiter]

Its the dowels strength in bending. Nothing to do with the concrete really. The tables just assume 8" embedment I believe. If your concrete is going to control over the bearing on the wood and bending of the bolt then you need a separate check for that.

 

[DTS419]

drift, I’m not sure about that. The bolt strength is accounted for separately, and Fe for the wood side member is a function of species. I’m pretty sure Fe is concerning the bearing strength of the material that the bolt is bearing against.

 

[SWComposites]

wait, are you asking about bolts or wood dowels?
bolt? presumably these are metal (steel)??
wood dowel? why would you use a wood dowel into concrete??

 

[Eng16080]

The dowel bearing strength of a fastener embedded in concrete and the compressive strength of concrete (fc') are simply two different values. If you refer to AWC TR12 (which is the document that the NDS dowel lateral design values are based on), Appendix A, you'll see what I mean. That document lists Fe for concrete as Fe = 3*fc', but no greater than 7500 psi. I believe it's limited to 7500 psi due to limited test data for dowels embedded in higher strength concrete.

 

[driftLimiter]

drift, I’m not sure about that. The bolt strength is accounted for separately, and Fe for the wood side member is a function of species. I’m pretty sure Fe is concerning the bearing strength of the material that the bolt is bearing against.

Yes your right sorry I jumped into this one perhaps too quickly. I think the conclusion is still the same though. You can check the ACI requirements for anchorage if you are worried about exceeding that.

 

[DTS419]

wait, are you asking about bolts or wood dowels?
bolt? presumably these are metal (steel)??
wood dowel? why would you use a wood dowel into concrete??

Lol, I see the confusion in my thread title. I should have said "Wood Design Dowel Bearing Strength."

The question comes from Chapter 12 of the American Wood Council's (AWC) National Design Standard (NDS) the gives provisions for the design of bolted connections in wood members, and in this case, wood to concrete.

Still not sure I follow how we get a bearing strength that is 3x the compressive strength of the concrete; you won't get that by following the ACI provisions for bearing strength.