Transverse concentrated forces on plates and HSS.

Prior to the inclusion of these provisions in the AISC spec, it likely would have been up to the discretion of the designing engineer. If the design guides authored by Packer, CIDECT etc were available -- and the designer was aware of them -- the result might be the same. If not, the designer might have attempted the design via the yield line method or some, cruder, method such as strip design.

I know the equation for pipes and tubes were in the AISC360-10, but, what happened with webs? There was a procedure or design example?

Thanks.

It wasn't explicitly defined in the code.

Actually, it still isn't. This is in the manual section, not the code itself. The manual gives lots of guidance but is not all inclusive. So, in previous versions engineers had to come up with their own methods of evaluating this. Now, there were published papers that addressed the subject. Or design guides that included it. However, you had to find them yourself.

I remember working on RISAConnection (back when I worked for RISA), and I really wanted to add in a failure state for a plate connected to the web of a column like this. I was directing most of the development of that program at the time. But, the current CEO wouldn't let us do it because it wasn't in the AISC manual yet. Therefore, the program just ignored this possible failure method for a few years. Only added it when it got into the AISC manual. It didn't matter that I'd gotten the equations (and references to papers) from AISC committee meetings on connections.

That's the danger of having PR / Marketing people run an engineering company.... A new feature is not worthwhile just because it addresses a serious safety issue. It's only worthwhile if they can "sell it" easily. I guess it was inevitable that, after butting heads for a few years, I would leave as soon as she took over the company completely. Not sure why I didn't see it coming.

My question is how was this effect (out-of-plane forces) evaluated for the previous version of AISC codes?

Click to expand...

As far as HSS goes, that's been in codes for a while. For example, the 1997 'Hollow Structural Sections Connections Manual' (by AISC) has formulas for such situations.

For a beam web, it's a little trickier. Prior to the code addressing it (which didn't happen until the last few editions IIRC)....a few AISC Journal articles addressed it in decades past. Blodgett's book on welded structures had a means to address it. (But it was a bit conservative if memory serves.) A steel connection book I bought about 20 years ago addressed this with a yield line equation.

These equations added in the 15th manual for forces on webs are truly just a simplification of the equations that would result from the yield line analysis - hence why the equation is simply just the flexural capacity of the plate multiplied by a bunch of geometric ratios.

While these simplifications are convenient they actually take away from the more powerful tool which is understanding how to perform a yield line analysis, which is what someone hopefully would've have done prior to these equations being added to the manual as others have mentioned. Plus, yield line analysis is also just an awesome application of a basic principle, work-energy, that feels satisfying to employ when practical in today's rather prescriptive procedures of being a structural engineer.