Steel Shapes

[JedClampett]

How many of you size angles, rectangular HSS, etc. based on the theory that equal leg angles or equal size (square) HSS are easier to CAD and reduce confusion in the field?
I'm doing some steel design and thinking about how often equal leg angles, square tubes or round tubes ae my go-to design options.

 

[phamENG]

I can't say that's ever been my motivation. I think square HSS is generally more available than rectangular, but not all square sizes are. Probably the same for equal leg angles. So it's a bit self perpetuating. Design choices favored equal legs/sides, so supply shaped to meet that demand, and designers continued to choose them to follow supply.

Most architectural designs call for square columns. If they don't, then using a square column can give an opportunity to create a concealed chase in an architectural wrap.

Loose lintel angles - with air spaces growing ever larger for insulation, you'd have to use an L8x8 for every window. So I use equal legs there less and less.

 

[dik]

It's never been a consideration... over the decades, I've got blocks for hundreds of shapes... filed as:

and under 05-Metals:

and under Sections:

and under L:

You can see from the dates that they have been accumulated over the years.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[WARose]

When it comes to angles, definitely. Also, equal leg angles are easier to do the calculations on. (IMO)

 

[human909]

Never. Rectangular hollow section and unequal angles are common enough in my locality and in my past experience as a steel detailer I've never found them more challenging.

I use unequal angles as standard for steel joists in my structures.

 

[skeletron]

I would say that I steer towards "equal sides = less mistakes". HSS square is just so common, but if the contractor wanted to sub for a rectangular I would do the check. Angles I'll default to equal, but there are times where a long-leg angle will be a better solution.

 

[dik]

...often with steel connections in fitting the connection on to the web, or face of an HSS.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Aesur]

Never - I use what is needed calc wise, but also consider weight of steel and availability. I haven't encountered much confusion in the field (that I have been privy to) thus far.

 

[271828]

For angles, the vast majority of the time I've made them equal leg. Just not a lot of advantage typically to making them different.

If an HSS is in bending and is not tiny, it'll probably be rectangular. Otherwise square.

 

[JedClampett]

As a background, I'm used to CAD technicians that do not have any physical understanding of steel shapes. We do a lot of materials, but I'm talking about pretty easy steel designs. Things are much better now, but I have techs who:
[ul]
[li]Get the grating bearing bar direction wrong every time. It's amazing that they don't get it right half the time. It's a 50/50 call.[/li]
[li]Don't understand, can't understand and will never understand why I want to show the flanges of channels direction.[/li]
[li]Need help in showing W18's and W8's different.[/li]
[/ul]
Luckily we always get shop drawings for steel. And the detailers are pretty good.

 

[human909]

I think most of the differences in responses come from different areas of practice and different use cases. There really are noticeable advantages and if you aren't observing them in your work then it it likely just a case of not encountering the suitable use cases. For me it is simply a case of using the appropriate member in the appropriate place.

Unequal angles and rectangular HSS are naturally inherently more efficient and often even more practical in bending. Thus if you need such members as beams or stiffening items the they are great. For compression they are normally less efficient (assuming equal effective length) so using them is less likely unless there is another need due to space requirement etc.

My use cases for unequal angles:
-Standard members for floor joist on metal deck industrial structures
-Standard members for stiffeners on storage bins

My use cases for rectangular HSS
-Major and minor beams on structures that have a requirement for closed sections (often hygiene requirements).
-Stand alone beams long span without lateral restraint (eg a light pipe support), a open section would face LTB issues. Whereas I can get a 250x150RHS to span 12.5m on its own. (10" deep, spanning 41feet for those using funny units)
-beams on minor fabricated equipment supports where HSS might make more sense than open sections