Steel Angle Column Base Plate Design 2

[AntT]

Hello everyone,

Could someone provide me with a reference that explains a way for designing base plates with Steel Angles (L shapes) as columns? AISC Design Guide 1 specifies the design process only for W-Shape and HSS/Pipe.

Thank you,
Anthony

 

[KootK]

Design Guide one has a procedure for lightly loaded base plates where you just use a strip of steel near to the plate elements of the supported section. I'd use that same procedure applied to your angle.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[AntT]

Hello KootK,

I am having trouble finding the section where lightly loaded base plates are discussed. Is that section available in the AISC Design Guide 1 (2nd Edition), if so where within the text?

 

[WARose]

I've solved this (in the past) with an FEA model in about 10 minutes flat. If there is no uplift....we are talking a (even faster) hand calculation.

If you don't have the software, there are other things to try.....but I thought I'd suggest that first.

 

[JoelTXCive]

Here is a detail that i came across on an old set of plans in our office.

It was used on a small work platform 36" above ground. I don't know the whereabouts of the supporting calcs.

 

[XR250]

It was used on a small work platform 36" above ground. I don't know the whereabouts of the supporting calcs.

They probably never existed

 

[dik]

Try using 1/2" offset all around the angle and see if the bearing capacity works on confined bearing. If OK then treat it as a 1/2" cantilevered plate. to check to see if 3/8 thickness works.

Dik

 

[rowingengineer]

For interesting connections we have been using

https://www.ideastatica.com/steel/

there is a instresting learning curve but once done the program is very easy to use.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[TLHS]

What's the loading like? If it's an angle the loads are likely tiny and I suspect the plate is fine in compression in almost pure bearing through the plate and into the concrete without much bending actually happening in the plate. If you want to assume equal bearing under the plate, fine. Find the furthest perpendicular distance between a plate edge and a leg of the angle and use that for your plate cantilever distance. Use the full plate width for resistance width. Conservative, but a quick calc and your plate is likely still going to be thin given the loads.

For tension measure from the bolt to a reasonable point on the angle (will depend on the orientation) and make an assessment based on a conservative width in bending.

For low load applications where the arrangements are awkward to do the math on, just make conservative assumptions that keep the math simple. You're not going to save money on the steel compared to the amount of work you put in.

Realistically, the angle is likely going to force a hinge in the plate at the diagonal between the two tips of the angle. You also can't fail a plate without the hinge going to the edge at some point. So bending width equal to the plate width is likely conservative for a reasonably size, reasonable thickness plate.