HSS vs. W-Flange and Angle Costs

[TTUengr51]

I'm currently providing some design alternates for a steel frame sign structure. The original design incorporated HSS columns and HSS secondary frame members. Our proposed alternate is using W-flange columns and angle secondary framing.

Based on a weight comparison, the W-flange/angle frame is lighter. However, I have heard before that the cost difference per pound between HSS and W-flange/angle is not 1:1, but HSS is typically more expensive per pound. Does anyone have a feel for what the cost difference may actually be?



Nick Deal, P.E.
Michael Brady Inc.

http://www.michaelbradyinc.com

 

[jike]

Check Means for cost data or call a local fabricator

 

[lkjh345]

I have heard, all other things being equal, anywhere from 1.1x to 1.5x depending on all kinds of factors (exact shapes you are comparing, local availability, whether you call on a Tuesday or a Thursday, etc....).

For a 'ballpark' estimate, I use 1.25 to 1.33. I'm guessing this is a number that has a high degree of local variability.

 

[Den32]

Typically use $1.50 per pound for W-shapes and $2 per pound for HSS members....but the steel market has fluctuated so much, best bet would be to call a Steel Fabricator

 

[enginerding]

I would caution against too much angle framing in the superstructure. If the people servicing the sign need to be climbing up, over, and around all sorts of web members, there is a huge risk of falling. Many of the sign companies we deal with are converting angle-framed truss superstructures with wide flange structures for just this reason.

A simple superstructure without truss framing makes for quicker work on the sign as well. It might be cheaper to build with angle trusses, but if your service men spend twice as much time on the sign climbing like monkeys, all potential gain will be lost in a matter of a few years in service.

 

[lrhg]

You also might want to look at connection cost. All welded HHS connections would be more costly than bolted WF conx.
Fewer heavier members will also improve fabrication and erection costs - fewer pieces to fab, ship, lift and erect.

Lowest weight is not always lowest cost.