Coefficient of friction for steel base plate to concrete 3

[GD_P]

Hello,

What value of coefficient of friction do you consider, when base plate shear is transferred through friction?
If you refer Eurocode EN 1993-1-8, Cl. 6.2.2(6), it specified only 0.2 for Sand & cement mortar with steel.
Whereas for AISC Steel design guide 1 : Base Plate and Anchor Rod Design, Cl. 3.5.1 specifies 0.55 for steel to mortar & 0.7 for steel to concrete.

Thanks in advance.

GD_P

 

[BridgeSmith]

"I've handled this a few times and what I did was..."

Your approach sounds like it would work to give some friction resistance through the base plate to grout interface, although if you're going to embed the base plate in grout, I don't see the advantage of using the leveling nuts. Why wouldn't you just press the base plate into the wet grout, snug the top nuts and torque them after the grout sets up?

I've never really given it much thought; we've never had a situation where the shear capacity of the anchor bolts wasn't adequate.

 

[WARose]

Your approach sounds like it would work to give some friction resistance through the base plate to grout interface, although if you're going to embed the base plate in grout, I don't see the advantage of using the leveling nuts. Why wouldn't you just press the base plate into the wet grout, snug the top nuts and torque them after the grout sets up?

Excellent question. The times I have used this is when I have issued a design (with grout under the plate, and the fabricated steel has been delivered to the field) and the contractor has said he had to have leveling nuts. (Or at the least: they said it was much easier with nuts than anything else.)

With the relatively light loads during erection....it typically shouldn't be an issue. Of course, sometimes they just flat forget. Once I went out into the field, and they practically had the whole thing built and it was still sitting on erection nuts. (About as mad as I've ever been.)