## Design of Shear key for Steel column

## Design of Shear key for Steel column

(OP)

Hi,

I am to design a shear key for a steel column of a braced bay in a pipe rack. Since there is a significant amount of shear at column base which is difficult to be borne by anchor bolts ,shear key has been envisaged.

My problem is where ever i seen calculation for the design of a typical shear key element (rolled section or plates in + shape welded at the bottom the base plate )flexural stress of this element (shear key depth is 200mm + 25grout-10mm gap = 215mm)has been calculated .

My question is why we need to check the flexural stress of this element when there is no place for this element to bend (shear key will be filled with non-shrink grout)?

I am to design a shear key for a steel column of a braced bay in a pipe rack. Since there is a significant amount of shear at column base which is difficult to be borne by anchor bolts ,shear key has been envisaged.

My problem is where ever i seen calculation for the design of a typical shear key element (rolled section or plates in + shape welded at the bottom the base plate )flexural stress of this element (shear key depth is 200mm + 25grout-10mm gap = 215mm)has been calculated .

My question is why we need to check the flexural stress of this element when there is no place for this element to bend (shear key will be filled with non-shrink grout)?

## RE: Design of Shear key for Steel column

One other method that you could consider is to embed horizontal steel plates in the top surface of the concrete, on either side of the base plate. Then, after the base plate is installed, bolted down, and grouted, you can place twin vertical plates that weld to the embed and extend up the sides of the base plate - with a welded connection there. This would then take horizontal shear out of the base plate and deliver it to the concrete support.

## RE: Design of Shear key for Steel column

## RE: Design of Shear key for Steel column

## RE: Design of Shear key for Steel column

anchor bolt elongation

base plate bending

footing rotation

## RE: Design of Shear key for Steel column

Well coming back to my original question, do i still need to check my shear key element for bending. Even if you have grout/vent holes in the base plate do you still see any possibilities of pockets etc in the shear key.

## RE: Design of Shear key for Steel column

## RE: Design of Shear key for Steel column

Even though widely spaced bolts will tend to act like a fixed connection this is probably not going to be significant in a braced frame.

You should consider concrete bearing and breakout. Bearing will be important for sizing the shear key but if you have small pedestals then breakout could govern design. For breakout I would use ACI318 App D with fictitious bolt centers at the edges of the shear key. Otherwise I don't know of any published methods.

## RE: Design of Shear key for Steel column

Thanks again for you comments guys.